WorldWideScience

Sample records for plate flow chamber

  1. Analysis of the contribution of sedimentation to bacterial mass transport in a parallel plate flow chamber

    NARCIS (Netherlands)

    Li, Jiuyi; Busscher, Henk J.; Norde, Willem; Sjollema, Jelmer

    2011-01-01

    In order to investigate bacterium-substratum interactions, understanding of bacterial mass transport is necessary. Comparisons of experimentally observed initial deposition rates with mass transport rates in parallel-plate-flow-chambers (PPFC) predicted by convective-diffusion yielded deposition

  2. Improvements to parallel plate flow chambers to reduce reagent and cellular requirements

    Directory of Open Access Journals (Sweden)

    Larson Richard S

    2001-09-01

    Full Text Available Abstract Background The parallel plate flow chamber has become a mainstay for examination of leukocytes under physiologic flow conditions. Several design modifications have occurred over the years, yet a comparison of these different designs has not been performed. In addition, the reagent requirements of many designs prohibit the study of rare leukocyte populations and require large amounts of reagents. Results In this study, we evaluate modifications to a newer parallel plate flow chamber design in comparison to the original parallel plate flow chamber described by Lawrence et al. We show that modifications in the chamber size, internal tubing diameters, injection valves, and a recirculation design may dramatically reduce the cellular and reagent requirements without altering measurements. Conclusions These modifications are simple and easily implemented so that study of rare leukocyte subsets using scarce or expensive reagents can occur.

  3. Flow Characteristics of Multi-circular Jet Plate in Premix Chamber of Air-Assist Atomizer for Burner System

    Directory of Open Access Journals (Sweden)

    Amirnordin Shahrin Hisham

    2016-01-01

    Full Text Available The flow characteristics of multi-circular jet (MCJ plate in the premix chamber of an atomizer were investigated using Computational Fluid Dynamics. Multiphase volume of fluid behavior inside the chamber was determined via steady simulations. The Eulerian–Eulerian two-fluid approach was used for execution mixing of diesel fuel and air. Spray simulation using the discrete phase with injection was generated from the nozzle hole into the ambient atmosphere. The behavior of three MCJ plates in the premix chamber was studied numerically. Results illustrated that plate open area, Ae, influenced the turbulence inside the chamber. MCJ 3, which had the lowest open area, generated the highest flow velocity and turbulence kinetic energy compared with MCJ 1 and 2. The MCJ plates could increase the turbulence in the premix chamber and contribute to the combustion efficiency.

  4. DEVELOPMENT AND USE OF A PARALLEL-PLATE FLOW CHAMBER FOR STUDYING CELLULAR ADHESION TO SOLID-SURFACES

    NARCIS (Netherlands)

    VANKOOTEN, TG; SCHAKENRAAD, JM; VANDERMEI, HC; BUSSCHER, HJ

    A parallel-plate flow chamber is developed in order to study cellular adhesion phenomena. An image analysis system is used to observe individual cells exposed to flow in situ and to determine area, perimeter, and shape of these cells as a function of time and shear stress. With this flow system the

  5. Early biofilm formation and the effects of antimicrobial agents on orthodontic bonding materials in a parallel plate flow chamber

    NARCIS (Netherlands)

    Chin, Yeen; Busscher, HJ; Evans, R; Noar, J; Pratten, J

    Decalcification is a commonly recognized complication of orthodontic treatment with fixed appliances. A technology, based on a parallel plate flow chamber, was developed to investigate early biofilm formation of a strain of Streptococcus sanguis on the surface of four orthodontic bonding materials:

  6. Air bubble-induced detachment of polystyrene particles with different sizes from collector surfaces in a parallel plate flow chamber

    NARCIS (Netherlands)

    Gomez-Suarez, C; van der Mei, HC; Busscher, HJ

    2001-01-01

    Particle size was found to be an important factor in air bubble-induced detachment of colloidal particles from collector surfaces in a parallel plate flow chamber and generally polystyrene particles with a diameter of 806 nm detached less than particles with a diameter of 1400 nm. Particle

  7. Detachment of polystyrene particles from collector surfaces by surface tension forces induced by air-bubble passage through a parallel plate flow chamber

    NARCIS (Netherlands)

    Wit, PJ; vanderMei, HC; Busscher, HJ

    1997-01-01

    By allowing an air-bubble to pass through a parallel plate flow chamber with negatively charged, colloidal polystyrene particles adhering to the bottom collector plate of the chamber, the detachment of adhering particles stimulated by surface tension forces induced by the passage of a liquid-air

  8. Micro plate fission chamber development

    International Nuclear Information System (INIS)

    Wang Mei; Wen Zhongwei; Lin Jufang; Jiang Li; Liu Rong; Wang Dalun

    2014-01-01

    To conduct the measurement of neutron flux and the fission rate distribution at several position in assemblies, the micro plate fission chamber was designed and fabricated. Since the requirement of smaller volume and less structure material was taken into consideration, it is convinient, commercial and practical to use fission chamber to measure neutron flux in specific condition. In this paper, the structure of fission chamber and process of fabrication were introduced and performance test result was presented. The detection efficiency is 91.7%. (authors)

  9. Detachment of colloidal particles from collector surfaces with different electrostatic charge and hydrophobicity by attachment to air bubbles in a parallel plate flow chamber

    NARCIS (Netherlands)

    Suarez, CG; van der Mei, HC; Busscher, HJ

    1999-01-01

    The detachment of polystyrene particles adhering to collector surfaces with different electrostatic charge and hydrophobicity by attachment to a passing air bubble has been studied in a parallel plate flow chamber. Particle detachment decreased linearly with increasing air bubble velocity and

  10. Influence of shear on microbial adhesion to PEO-brushes and glass by convective-diffusion and sedimentation in a parallel plate flow chamber

    NARCIS (Netherlands)

    Roosjen, A; Boks, NP; van der Mei, HC; Busscher, HJ; Norde, W

    2005-01-01

    Microbial adhesion to surfaces often occurs despite high wall shear rates acting on the adhering microorganisms. In this paper, we compare the wall shear rates needed to prevent microbial adhesion to bare glass and poly(ethylene oxide) (PEO)-brush coated glass in a parallel plate flow chamber.

  11. Analysis of the contribution of sedimentation to bacterial mass transport in a parallel plate flow chamber Part II : Use of fluorescence imaging

    NARCIS (Netherlands)

    Li, Jiuyi; Busscher, Henk J.; van der Mei, Henny C.; Norde, Willem; Krom, Bastiaan P.; Sjollema, Jelmer

    2011-01-01

    Using a new phase-contrast microscopy-based method of analysis, sedimentation has recently been demonstrated to be the major mass transport mechanism of bacteria towards substratum surfaces in a parallel plate flow chamber (J. Li, H.J. Busscher, W. Norde, J. Sjollema, Colloid Surf. B. 84 (2011)76).

  12. Characterizing the adhesion of motile and nonmotile Escherichia coli to a glass surface using a parallel-plate flow chamber.

    Science.gov (United States)

    McClaine, Jennifer W; Ford, Roseanne M

    2002-04-20

    A parallel-plate flow chamber was used to measure the attachment and detachment rates of Escherichia coli to a glass surface at various fluid velocities. The effect of flagella on adhesion was investigated by performing experiments with several E. coli strains: AW405 (motile); HCB136 (nonmotile mutant with paralyzed flagella); and HCB137 (nonmotile mutant without flagella). We compared the total attachment rates and the fraction of bacteria retained on the surface to determine how the presence and movement of the flagella influence transport to the surface and adhesion strength in this dynamic system. At the lower fluid velocities, there was no significant difference in the total attachment rates for the three bacterial strains; nonmotile strains settled at a rate that was of the same order of magnitude as the diffusion rate of the motile strain. At the highest fluid velocity, the effect of settling was minimized to better illustrate the importance of motility, and the attachment rates of both nonmotile strains were approximately five times slower than that of the motile bacteria. Thus, different processes controlled the attachment rate depending on the parameter regime in which the experiment was performed. The fractions of motile bacteria retained on the glass surface increased with increasing velocity, whereas the opposite trend was found for the nonmotile strains. This suggests that the rotation of the flagella enables cells to detach from the surface (at the lower fluid velocities) and strengthens adhesion (at higher fluid velocities), whereas nonmotile cells detach as a result of shear. There was no significant difference in the initial attachment rates of the two nonmotile species, which suggests that merely the presence of flagella was not important in this stage of biofilm development. Copyright 2002 Wiley Periodicals, Inc.

  13. A multi-component parallel-plate flow chamber system for studying the effect of exercise-induced wall shear stress on endothelial cells.

    Science.gov (United States)

    Wang, Yan-Xia; Xiang, Cheng; Liu, Bo; Zhu, Yong; Luan, Yong; Liu, Shu-Tian; Qin, Kai-Rong

    2016-12-28

    In vivo studies have demonstrated that reasonable exercise training can improve endothelial function. To confirm the key role of wall shear stress induced by exercise on endothelial cells, and to understand how wall shear stress affects the structure and the function of endothelial cells, it is crucial to design and fabricate an in vitro multi-component parallel-plate flow chamber system which can closely replicate exercise-induced wall shear stress waveforms in artery. The in vivo wall shear stress waveforms from the common carotid artery of a healthy volunteer in resting and immediately after 30 min acute aerobic cycling exercise were first calculated by measuring the inner diameter and the center-line blood flow velocity with a color Doppler ultrasound. According to the above in vivo wall shear stress waveforms, we designed and fabricated a parallel-plate flow chamber system with appropriate components based on a lumped parameter hemodynamics model. To validate the feasibility of this system, human umbilical vein endothelial cells (HUVECs) line were cultured within the parallel-plate flow chamber under abovementioned two types of wall shear stress waveforms and the intracellular actin microfilaments and nitric oxide (NO) production level were evaluated using fluorescence microscope. Our results show that the trends of resting and exercise-induced wall shear stress waveforms, especially the maximal, minimal and mean wall shear stress as well as oscillatory shear index, generated by the parallel-plate flow chamber system are similar to those acquired from the common carotid artery. In addition, the cellular experiments demonstrate that the actin microfilaments and the production of NO within cells exposed to the two different wall shear stress waveforms exhibit different dynamic behaviors; there are larger numbers of actin microfilaments and higher level NO in cells exposed in exercise-induced wall shear stress condition than resting wall shear stress condition

  14. A very large multigap resistive plate chamber

    CERN Document Server

    Cerron-Zeballos, E; Hatzifotiadou, D; Kim, D W; Lamas-Valverde, J; Lee, S C; Platner, E D; Roberts, J; Williams, M C S; Zichichi, A

    1999-01-01

    We have built and tested a very large multigap resistive plate chamber (MRPC). We discuss the suitability of the multigap RPC for the construction of large area modules. We give details of the construction technique and results from a scan across the surface of the chamber. We also report on the implementation of `half-strip resolution', where we improve the spatial resolution by a factor 2 without increasing the number of read-out channels. (9 refs).

  15. Fabrication of resistive plate chamber using bakelite

    International Nuclear Information System (INIS)

    Neog, Himangshu; Bhuyan, M.R.; Biswas, S.; Mohanty, B.; Mohanty, Rudranarayan; Rudra, Sharmili; Sahu, P.K.; Sahu, S.

    2014-01-01

    Now a days Resistive Plate Chamber (RPC) is one of the most important detectors in the High Energy Physics (HEP) experiments. RPC is a gas filled detector utilizing a constant and uniform electric field produced between two parallel electrode plates made of a material with high bulk resistivity e.g. glass or bakelite. RPC has good time resolution (1-2 ns) and spatial resolution (∼ cm). The high resistance of RPC plate limits the spark size produced after the ionization of gas due to the passing charged particle. This contribution discusses building of a RPC using bakelite (local sources) and the measurement of the surface resistivity of the detector

  16. The wide gap resistive plate chamber

    International Nuclear Information System (INIS)

    Crotty, I.; Lamas Valverde, J.; Hatzifotiadou, D.; Williams, M.C.S.; Zichichi, A.

    1995-01-01

    The resistive plate chamber (RPC) has good time and position resolution; these factors (coupled to its simple construction) make it an attractive candidate for muon trigger systems at future colliders. However, operated in spark mode, the RPC has severe rate problems that make it unusable above 10 Hz/cm 2 . We have previously published our results concerning the operation of the RPC in spark and in avalanche mode; we have shown that the rate limit can be increased to 150 Hz/cm 2 if the RPC is operated in avalanche mode. Here, we discuss the performance of chambers with 6 and 8 mm gas gaps (compared to the more usual 2 mm gap). We outline the reasons for this choice, and also discuss anode versus cathode strip readout. We have measured the efficiency versus flux, and also show that an enhanced rate limit can be obtained if only a small region of the chamber is exposed to the beam (spot illumination). Finally we have tested the performance of chambers constructed with other materials for the resistiv e plate and compare it to chambers constructed with our preferred plastic, melamine laminate. (orig.)

  17. The micro-gap resistive plate chamber

    CERN Document Server

    Cerron-Zeballos, E; Lamas-Valverde, J; Platner, E D; Roberts, J; Williams, M C S; Zichichi, A

    1999-01-01

    Previously we have found that the freon C/sub 2/F/sub 5/H has very good properties when used in a resistive plate chamber (RPC) with a single gap of 2 mm. In this paper we report on the performance of a multigap RPC consisting of 4 gaps of 0.8 mm filled with a gas mixture containing this freon. (7 refs).

  18. High counting rate resistive-plate chamber

    International Nuclear Information System (INIS)

    Peskov, V.; Anderson, D.F.; Kwan, S.

    1993-05-01

    Parallel-plate avalanche chambers (PPAC) are widely used in physics experiments because they are fast ( 5 counts/mm 2 . A resistive-plate chamber (RPC) is similar to the PPAC in construction except that one or both of the electrodes are made from high resistivity (≥10 10 Ω·cm) materials. In practice RPCs are usually used in the spark mode. Resistive electrodes are charged by sparks, locally reducing the actual electric field in the gap. The size of the charged surface is about 10 mm 2 , leaving the rest of the detector unaffected. Therefore, the rate capability of such detectors in the spark mode is considerably higher than conventional spark counters. Among the different glasses tested the best results were obtained with electron type conductive glasses, which obey Ohm's law. Most of the work with such glasses was done with high pressure parallel-plate chambers (10 atm) for time-of-flight measurements. Resistive glasses have been expensive and produced only in small quantities. Now resistive glasses are commercially available, although they are still expensive in small scale production. From the positive experience of different groups working with the resistive glasses, it was decided to review the old idea to use this glass for the RPC. This work has investigated the possibility of using the RPC at 1 atm and in the avalanche mode. This has several advantages: simplicity of construction, high rate capability, low voltage operation, and the ability to work with non-flammable gases

  19. Air bubble-induced detachment of positively and negatively charged polystyrene particles from collector surfaces in a parallel-plate flow chamber

    NARCIS (Netherlands)

    Gomez-Suarez, C; Van der Mei, HC; Busscher, HJ

    2000-01-01

    Electrostatic interactions between colloidal particles and collector surfaces were found tcr be important in particle detachment as induced by the passage of air bubbles in a parallel-plate Row chamber. Electrostatic interactions between adhering particles and passing air bubbles, however, a-ere

  20. Resistive Plate Chambers for Imaging Calorimetry - the DHCAL

    CERN Document Server

    Repond, Jose

    2014-01-01

    The DHCAL, the Digital Hadron Calorimeter, is a prototype calorimeter based on Resistive Plate Chambers (RPCs). The design emphasizes the imaging capabilities of the detector in an effort to optimize the calorimeter for the application of Particle Flow Algorithms (PFAs) to the reconstruction of hadronic jet energies in a colliding beam environment. The readout of the chambers is segmented into 1 x 1 cm2 pads, each read out with a 1-bit (single threshold) resolution. The prototype with approximately 500,000 readout channels underwent extensive testing in both the Fermilab and CERN test beams. This talk presents preliminary findings from the analysis of data collected at the test beams.

  1. The physics of Resistive Plate Chambers

    CERN Document Server

    Riegler, Werner

    2004-01-01

    Over the last 3 years we investigated theoretical aspects of Resistive Plate Chambers (RPC) in order to clarify some of the outstanding questions on space charge effects, high efficiency of small gap RPCs, charge spectra, signal shape and time resolution. In a series of reports we analyzed RPC performance including all detector aspects covering primary ionization, avalanche multiplication, space charge effects, signal induction in presence of resistive materials, crosstalk along detectors with long strips and front-end electronics. Using detector gas parameters entirely based on theoretical predictions and physical models for avalanche development and space charge effects we are able to reproduce measurements for 2 and 0.3 mm RPCs to very high accuracy without any additional assumptions. This fact gives a profound insight into the workings of RPCs and also underlines the striking difference in operation regime when compared to wire chambers. A summary of this work as well as recent results on three-dimensiona...

  2. Simulation of the CMS Resistive Plate Chambers

    CERN Document Server

    Hadjiiska, R; Pavlov, B; Petkov, P; Dimitrov, A; Beernaert, K; Cimmino, A; Costantini, S; Garcia, G; Lellouch, J; Marinov, A; Ocampo, A; Strobbe, N; Thyssen, F; Tytgat, M; Verwilligen, P; Yazgan, E; Zaganidis, N; Aleksandrov, A; Genchev, V; Iaydjiev, P; Rodozov, M; Shopova, M; Sultanov, G; Ban, Y; Cai, J; Xue, Z; Ge, Y; Li, Q; Qian, S; Avila, C; Chaparro, L F; Gomez, J P; Moreno, B Gomez; Oliveros, A F Osorio; Sanabria, J C; Assran, Y; Sharma, A; Abbrescia, M; Colaleo, A; Pugliese, G; Loddo, F; Calabria, C; Maggi, M; Benussi, L; Bianco, S; Colafranceschi, S; Piccolo, D; Carrillo, C; Iorio, O; Buontempo, S; Paolucci, P; Vitulo, P; Berzano, U; Gabusi, M; Kang, M; Lee, K S; Park, S K; Shin, S; Kim, M S; Seo, H; Goh, J; Choi, Y; Shoaib, M

    2013-01-01

    The Resistive Plate Chamber (RPC) muon subsystem contributes significantly to the formation of the trigger decision and reconstruction of the muon trajectory parameters. Simulation of the RPC response is a crucial part of the entire CMS Monte Carlo software and directly influences the final physical results. An algorithm based on the parametrization of RPC efficiency, noise, cluster size and timing for every strip has been developed. Experimental data obtained from cosmic and proton-proton collisions at $\\sqrt{s}=7$ TeV have been used for determination of the parameters. A dedicated validation procedure has been developed. A good agreement between the simulated and experimental data has been achieved.

  3. Detector Physics of Resistive Plate Chambers

    CERN Document Server

    Lippmann, Christian; Riegler, W

    2003-01-01

    Resistive Plate Chambers (RPCs) are gaseous parallel plate avalanche detectors that implement electrodes made from a material with a high volume resistivity between 10^7 and 10^12 Ohm cm. Large area RPCs with 2mm single gaps operated in avalanche mode provide above 98% efficiency and a time resolution of around 1ns up to a flux of several kHz/cm2. These Trigger RPCs will, as an example, equip the muon detector system of the ATLAS experiment at CERN on an area of 3650m2 and with 355.000 independent read out channels. Timing RPCs with a gas gap of 0.2 to 0.3mm are widely used in multi gap configurations and provide 99% efficiency and time resolution down to 50ps. While their performance is comparable to existing scintillator-based Time-Of-Flight (TOF) technology, Timing RPCs feature a significantly, up to an order of magnitude, lower price per channel. They will for example equip the 176m2 TOF barrel of the ALICE experiment at CERN with 160.000 independent read out cells. RPCs were originally operated in stream...

  4. The resistive plate chambers for CMS and their simulation

    Energy Technology Data Exchange (ETDEWEB)

    Abbrescia, M. E-mail: marcello.abbrescia@ba.infn.it; Colaleo, A.; Iaselli, G.; Loddo, F.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Pugliese, G.; Ranieri, A.; Romano, F.; Altieri, S.; Belli, G.; Bruno, G.; Guida, R.; Merlo, M.; Ratti, S.P.; Riccardi, C.; Torre, P.; Vitulo, P

    2001-09-21

    In this paper some results obtained by the CMS Resistive Plate Chamber collaboration during its five years long period of research and development are reported. The importance of the simulation in the design of the Resistive Plate Chambers for CMS is stressed.

  5. Angular dependence of the parallel plate ionization chambers of Ipen

    International Nuclear Information System (INIS)

    Albuquerque, M. da P.P.; Caldas, L.

    1989-08-01

    The ionization chambers with parallel plates designed and constructed at IPEN for the dosimetry of soft X-radiation fields were studied in relation to thein angular dependence between O and +- 90 0 . The objective of this study is to verify the chambers response variation for small positioning errors during the field dosimetry used in Radiotherapy. The results were compared with those of commercial parallel plate ionization chambers used as secondary and testiary standards. (author) [pt

  6. Growing and analyzing biofilms in flow chambers

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim; Sternberg, Claus

    2011-01-01

    This unit describes the setup of flow chamber systems for the study of microbial biofilms, and methods for the analysis of structural biofilm formation. Use of flow chambers allows direct microscopic investigation of biofilm formation. The biofilms in flow chambers develop under hydrodynamic......, and disassembly and cleaning of the system. In addition, embedding and fluorescent in situ hybridization of flow chamber-grown biofilms are addressed....

  7. Parallel Plate Chambers and their possible use in LHC experiments

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, Gy.L.; Bizzeti, A.; Choumilov, E.; Civinini, C.; D'Alessandro, R.; Dajko, G.; Fenyvesi, A.; Ferrando, A.; Fouz, M.C.; Iglesias, A.; Ivochkin, V.; Maggi, F.; Malinin, A.; Martinez-Laso, L.; Meschini, M.; Molnar, J.; Pojidaev, V.; Szoncso, F.; Wulz, C.E.

    1995-01-01

    Present status of Parallel Plate Chambers (PPC) is reviewed. After a description of this detector, results from tests concerning PPC efficiency uniformity, radiation hardness, and behaviour in electromagnetic calorimetry are presented. Some possible utilizations in LHC experiments are mentioned. (orig.)

  8. Resistive Plate Chambers for hadron calorimetry: Tests with analog readout

    Energy Technology Data Exchange (ETDEWEB)

    Drake, Gary [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Repond, Jose [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States)]. E-mail: repond@hep.anl.gov; Underwood, David [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Xia, Lei [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States)

    2007-07-21

    Resistive Plate Chambers (RPCs) are being developed for use in a hadron calorimeter with very fine segmentation of the readout. The design of the chambers and various tests with cosmic rays are described. This paper reports on the measurements with multi-bit (or analog) readout of either a single larger or multiple smaller readout pads.

  9. Construction and performance of a prototype multigap resistive plate chamber

    International Nuclear Information System (INIS)

    Ahn, S. H.; Hong, B.; Hong, S. J.

    2002-01-01

    We present the design, construction, and performance of a prototype multigap resistive plate chamber made of glass plates. A time resolution of 580 ps with a detection efficiency above 95 % was achieved at the working high-voltage plateau with cosmic ray muons

  10. Rate effects in resistive plate chambers

    International Nuclear Information System (INIS)

    Lippmann, C.; Riegler, W.; Kalweit, A.

    2006-01-01

    The resistive plates in RPCs cause a drop of the electric field in the gas gap at high particle rates or large gas gain, which affects efficiency and time resolution. This effect is typically estimated by assuming the particle flux to be a DC current that causes a voltage drop when it passes through the resistive plate. In an improved model by Abbrescia (Nucl. Instr. Meth. A 533 (2004) 7), the fluctuation of the field in the gas gap is modelled by assuming that the avalanche partially discharges a small capacitor which gets recharged with a time constant characteristic for the given RPC. In our approach, the effect is calculated by using the exact analytic solution for the time dependent electric field of a point charge sitting on the surface of a resistive plate in an RPC. This is, by definition, the best possible approximation to reality. The solution is obtained using the quasi-static approximation of Maxwell's equations. The formulas are presented as integral representations with 'cured' integrands, which allow easy numerical evaluation for Monte Carlo simulations. The solutions show that the charges in RPCs are 'destroyed' with a continuous distribution of time constants which are related in a very intuitive way to some limiting cases. Using these formulas we present a Monte Carlo simulation of rate effects, proving the applicability of this approach. Finally, we compare the Monte Carlo results to analytical calculations, similar to the ones proposed by Gonzalez-Diaz et al. (see proceedings of this conference)

  11. HF production in CMS-Resistive Plate Chambers

    International Nuclear Information System (INIS)

    Abbrescia, M.; Colaleo, A.; Guida, R.; Iaselli, G.; Loddo, F.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Pugliese, G.; Ranieri, A.; Romano, F.; Trentadue, R.; Cavallo, N.; Fabozzi, F.; Paolucci, P.; Piccolo, D.; Polese, G.; Sciacca, C.; Belli, G.; Necchi, M.; Ratti, S.; Riccardi, C.; Torre, P.; Vitulo, P.; Anguelov, T.; Genchev, V.; Panev, B.; Piperov, S.; Sultanov, G.; Vankov, P.; Litov, L.; Pavlov, B.; Petkov, P.

    2006-01-01

    The formation of highly reactive compounds in the gas mixture during Resistive Plate Chambers (RPCs) operation at the CERN Gamma Irradiation Facility (GIF) is studied. Results from two different types of chambers are discussed: 50 x 50 cm 2 RPC prototypes and two final CMS-RB1 chambers. The RB1 detectors were also connected to a closed loop gas system. Gas composition, possible additional impurities as well as fluoride ions have been monitored in different gamma irradiation conditions both in open and closed loop mode. The chemical composition of the RPC electrode surface has also been analyzed using an electron microscope equipped with an EDS/X-ray

  12. Growing and Analyzing Biofilms in Flow Chambers

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim; Sternberg, Claus

    2011-01-01

    This unit describes the setup of flow chamber systems for the study of microbial biofilms, and methods for the analysis of structural biofilm formation. Use of flow chambers allows direct microscopic investigation of biofilm formation. The biofilms in flow chambers develop under hydrodynamic......, and disassembly and cleaning of the system. In addition, embedding and fluorescent in situ hybridization of flow chamber–grown biofilms are addressed. Curr. Protoc. Microbiol. 21:1B.2.1-1B.2.17. © 2011 by John Wiley & Sons, Inc....

  13. Surface Aggregation of Candida albicans on Glass in the Absence and Presence of Adhering Streptococcus gordonii in a Parallel-Plate Flow Chamber: A Surface Thermodynamical Analysis Based on Acid-Base Interactions.

    Science.gov (United States)

    Millsap; Bos; Busscher; van der Mei HC

    1999-04-15

    Adhesive interactions between yeasts and bacteria are important in the maintenance of infectious mixed biofilms on natural and biomaterial surfaces in the human body. In this study, the extended DLVO (Derjaguin-Landau-Verwey-Overbeek) approach has been applied to explain adhesive interactions between C. albicans ATCC 10261 and S. gordonii NCTC 7869 adhering on glass. Contact angles with different liquids and the zeta potentials of both the yeasts and bacteria were determined and their adhesive interactions were measured in a parallel-plate flow chamber.Streptococci were first allowed to adhere to the bottom glass plate of the flow chamber to different seeding densities, and subsequently deposition of yeasts was monitored with an image analysis system, yielding the degree of initial surface aggregation of the adhering yeasts and their spatial arrangement in a stationary end point. Irrespective of growth temperature, the yeast cells appeared uncharged in TNMC buffer, but yeasts grown at 37 degrees C were intrinsically more hydrophilic and had an increased electron-donating character than cells grown at 30 degrees C. All yeasts showed surface aggregation due to attractive Lifshitz-van der Waals forces. In addition, acid-base interactions between yeasts, yeasts and the glass substratum, and yeasts and the streptococci were attractive for yeasts grown at 30 degrees C, but yeasts grown at 37 degrees C only had favorable acid-base interactions with the bacteria, explaining the positive relationship between the surface coverage of the glass by streptococci and the surface aggregation of the yeasts. Copyright 1999 Academic Press.

  14. Resistive plate chambers performances at cosmic rays fluxes

    International Nuclear Information System (INIS)

    Abbrescia, M.; Iaselli, G.

    1995-01-01

    In this paper detailed curves showing the behaviour of resistive plate chambers efficiency and time resolution as a function of temperature and operating voltage are presented. The results show that the operating voltage scales well according to the rule: operating voltage/gas density=constant. (orig.)

  15. A new type of resistive plate chamber: The multigap RPC

    International Nuclear Information System (INIS)

    Cerron Zeballos, E.; Crotty, I.; Hatzifotiadou, D.; Lamas Valverde, J.; Neupane, S.; Williams, M.C.S.; Zichichi, A.

    1996-01-01

    This Letter describes the multigap resistive plate chamber (RPC). The goal is to obtain a much improved time resolution, keeping the advantages of the wide gap RPC in comparison with the conventional narrow gap RPC (smaller dynamic range and thus lower charge per avalanche which gives higher rate capability and lower power dissipation in the gas gap). (orig.)

  16. A new type of resistive plate chamber the multigap RPC

    CERN Document Server

    Cerron-Zeballos, E; Hatzifotiadou, D; Lamas-Valverde, J; Neupane, S; Williams, M C S; Zichichi, Antonino

    1996-01-01

    This paper describes the multigap resistive plate chamber (RPC). The goal is to obtain a much improved time resolution, keeping the advantages of the wide gap RPC in comparison with the conventional narrow gap RPC (smaller dynamic range and thus lower charge per avalanche which gives higher rate capability and lower power dissipation in the gas gap).

  17. The HARP resistive plate chambers: Characteristics and physics performance

    International Nuclear Information System (INIS)

    Ammosov, V.; Boyko, I.; Chelkov, G.; Dedovitch, D.; Dumps, R.; Dydak, F.; Elagin, A.; Gapienko, V.; Gostkin, M.; Guskov, A.; Kroumchtein, Z.; Koreshev, V.; Linssen, L.; Nefedov, Yu.; Nikolaev, K.; Semak, A.; Sviridov, Yu.; Usenko, E.; Wotschack, J.; Zaets, V.; Zhemchugov, A.

    2007-01-01

    The HARP Resistive Plate Chamber (RPC) system was designed for time-of-flight measurement in the large-angle acceptance region of the HARP spectrometer. It comprised 46 four-gap glass RPCs covering an area of ∼8m 2 . The design of the RPCs, their operation, intrinsic properties, and system performance are described. The intrinsic time resolution of the RPCs is better than 130ps leading to a system time resolution of ∼175ps

  18. Avalanche and streamer mode operation of resistive plate chambers

    International Nuclear Information System (INIS)

    Cardarelli, R.; Makeev, V.; Santonico, R.

    1996-01-01

    A resistive plate chamber was operated at voltages increasing in steps of 200 V over a 3 kV interval and the transition between the avalanche and streamer modes was studied. The avalanche amplitude was observed to be exponentially dependent on the operating voltage up to a value, characteristic of the gas, where the avalanche saturation occurs and delayed streamer signals start to appear. Signal waveforms, charge and timing distributions are reported. (orig.)

  19. Avalanche fluctuations within the multigap resistive plate chamber

    International Nuclear Information System (INIS)

    Cerron Zeballos, E.; Crotty, I.; Lamas Valverde, J.; Veenhof, R.J.; Williams, M.C.S.; Zichichi, A.

    1996-01-01

    The multigap resistive plate chamber (MRPC) was originally designed to have improved time resolution (compared to the wide gap RPC), but also to keep the good high rate behaviour and ease of construction associated with the wide gap RPC. However in addition we observed a very long efficiency plateau, even at high rates. Here we consider fluctuations in avalanche growth, and show that the inherent ''averaging'' of these fluctuations can account for the enhanced performance of the multigap RPC. (orig.)

  20. Resistive Plate Chambers commissioning and performance results for 2015

    CERN Document Server

    CMS Collaboration

    2016-01-01

    The Resistive Plate Chamber (RPC) detector system at the Compact Muon Solenoid experiment at the LHC confers robustness and redundancy to the muon trigger. During the first long shutdown of the LHC (2013-2014) the CMS muon RPC system has been upgraded with 144 double-gap chambers on the forth forward stations. A total of 1056 double-gap chambers cover the pseudo-rapidity region up to 1.6. The main detector parameters are constantly and closely monitored to achieve operational stability and high quality data in the harsh conditions of the second run period of the LHC (13 TeV and 25 ns bunch spacing). Resistive Plate Chambers (RPC) performance results for 2015 with pp collisions at 13 TeV are presented. These results include the occupancy, efficiency of newly installed detectors after applying new working point, history plots for the RPC relevant variables such as: Cluster Size, Efficiency, percentage of inactive detector during operation and Rates and overall system noise. RPC variables are studied as funct...

  1. Study of an avalanche-mode resistive plate chamber

    International Nuclear Information System (INIS)

    Ying, J.; Ban, Y.; Liu, H.T.; Zhu, Z.M.; Zhu, Z.Y.; Chen, T.; Ma, J.G.; Ye, Y.L.

    2000-01-01

    Resistive plate chambers (RPCs) are widely used to detect high-energy charged particles, especially muons, due to the high gain, moderate time and spatial resolution, simple design and low cost of these detectors. While the simple streamer mode is adequate for cosmic-ray and low-rate accelerator experiments, the avalanche mode is required for high-rate experiments such as CMS at LHC. In this paper construction of a medium-sized double-gap RPC made of Chinese materials is reported. The experimental set-up of cosmic-ray and muon beam tests are introduced. The avalanche mode was clearly observed. Good efficiency and time resolution were obtained from the beam test at CERN under normal irradiation conditions. At very high radiation background the chamber efficiency decreases, indicating the necessity to change the resistivity value of the Chinese bakelites. (author)

  2. On aging problem of glass Resistive Plate Chambers

    International Nuclear Information System (INIS)

    Bhide, S.S.; Datar, V.M.; Kalmani, S.D.; Mondal, N.K.; Pant, L.M.; Satyanarayana, B.; Shinde, R.R.

    2006-01-01

    Resistive Plate Chambers (RPCs) were chosen to be the active elements for a 50kton neutrino detector, which is proposed to be built by the India-based Neutrino Observatory (INO) collaboration. As part of the detector R and D programme, we have built a large number of prototype RPCs and studied their characteristics. While, the results obtained by us are in agreement with those reported in the literature, the RPCs were observed to suffer severe damage when operated continuously for a few months. We summarise here our studies on this problem

  3. Simulation of Resistive Plate Chamber sensitivity to neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Altieri, S. E-mail: saverio.altieri@pv.infn.it; Belli, G.; Bruno, G.; Merlo, M.; Ratti, S.P.; Riccardi, C.; Torre, P.; Vitulo, P.; Abbrescia, M.; Colaleo, A.; Iaselli, G.; Loddo, F.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Pugliese, G.; Ranieri, A.; Romano, F

    2001-04-01

    The Resistive Plate Chambers (RPCs) sensitivity to neutrons has been simulated using GEANT code with MICAP and FLUKA interfaces. The calculations have been performed as a function of the neutrons energy in the range 0.02 eV-1 GeV. To evaluate the response of the detector in the LHC background environment, the neutron energy spectrum expected in the CMS muon barrel has been taken into account; a hit rate due to neutrons of about 0.6 Hz cm{sup -2} has been estimated for a 250x250 cm{sup 2} RPC in the RB1 station.

  4. Degradation in the efficiency of glass Resistive Plate Chambers operated without external gas supply

    Science.gov (United States)

    Baesso, P.; Cussans, D.; Thomay, C.; Velthuis, J.; Burns, J.; Quillin, S.; Stapleton, M.; Steer, C.

    2015-06-01

    Resistive plate chambers (RPC) are particle detectors commonly used by the high energy physics community. Their normal operation requires a constant flow of gas mixture to prevent self-poisoning which reduces the chamber's capability to detect particles. We studied how quickly the efficiency of two RPCs drops when operated in sealed mode, i.e. without refreshing the gas mixture. The test aim is to determine how RPCs could be used as particle detectors in non-laboratory applications, such as those exploiting muon tomography for geological imaging or homeland security. The two sealed RPCs were operated in proportional mode for a period of more than three months, and their efficiencies were recorded continuously and analysed in 8-hours intervals. The results show that the efficiency drops on average by 0.79 ± 0.01 % every 24 hours of operation and returns close to the initial value after purging the old gas mixture and flushing the chambers with fresh gas.

  5. Recombination: An important effect in multigap resistive plate chambers

    International Nuclear Information System (INIS)

    Doroud, K.; Afarideh, H.; Hatzifotiadou, D.; Rahighi, J.; Williams, M.C.S.; Zichichi, A.

    2009-01-01

    We have simulated the gas avalanche in a multigap resistive plate chamber (MRPC). The results were then compared with our data from the MRPC . Up to now, the total amount of charge produced in a gas gap is considered to be given by the total number of positive ions generated by the gas avalanches. However, the total charge generated by the simulation program is much too large and is in conflict with our data. Our data indicate that nearly 100% of the negative ions recombine with the positive ions. The recombination effect dramatically reduces the amount of charge in the gas gap: a very important feature for MRPC technology especially for the rate capability.

  6. Resistive Plate Chamber Digitization in a Hadronic Shower Environment

    CERN Document Server

    Deng, Z.

    2016-06-28

    The CALICE Semi-Digital Hadron Calorimeter (SDHCAL) technological prototype is a sampling calorimeter using Glass Resistive Plate Chamber detectors with a three-threshold readout as the active medium. This technology is one of the two options proposed for the hadron calorimeter of the International Large Detector for the International Linear Collider. The prototype was exposed to beams of muons, electrons and pions of different energies at the CERN Super Proton Synchrotron. To be able to study the performance of such a calorimeter in future experiments it is important to ensure reliable simulation of its response. In this paper we present our prototype simulation performed with GEANT4 and the digitization procedure achieved with an algorithm called SimDigital. A detailed description of this algorithm is given and the methods to determinate its parameters using muon tracks and electromagnetic showers are explained. The comparison with hadronic shower data shows a good agreement up to 50 GeV. Discrepancies are ...

  7. Development of linseed oil-free bakelite resistive plate chambers

    International Nuclear Information System (INIS)

    Biswas, S.; Bhattacharya, S.; Bose, S.; Chattopadhyay, S.; Saha, S.; Viyogi, Y.P.

    2009-01-01

    In this paper we would like to present a few characteristics of the Resistive Plate Chambers (RPCs) made of a particular grade of bakelite paper laminates (P-120, NEMA LI-1989 Grade XXX), produced and commercially available in India. This particular grade is used for high voltage insulation in humid conditions. The chambers are tested with cosmic rays in the streamer mode using argon, tetrafluroethane and isobutane in 34:59:7 mixing ratio. In the first set of detectors made with such grade, a thin coating of silicone fluid on the inner surfaces of the bakelite was found to be necessary for operation of the detector. Those silicone coated RPCs were found to give satisfactory performance with stable efficiency of >90% continuously for a long period as reported earlier. Results of the crosstalk measurement of these silicone coated RPC will be presented in this paper. Very recently RPCs made with the same grade of bakelite but having better surface finish are found to give equivalent performance even without any coating inside. Preliminary results of this type of RPCs are also being presented.

  8. Comparing Novel Multi-Gap Resistive Plate Chamber Models

    Science.gov (United States)

    Stien, Haley; EIC PID Consortium Collaboration

    2016-09-01

    Investigating nuclear structure has led to the fundamental theory of Quantum Chromodynamics. An Electron Ion Collider (EIC) is a proposed accelerator that would further these investigations. In order to prepare for the EIC, there is an active detector research and development effort. One specific goal is to achieve better particle identification via improved Time of Flight (TOF) detectors. A promising option is the Multi-Gap Resistive Plate Chamber (mRPC). These detectors are similar to the more traditional RPCs, but their active gas gaps have dividers to form several thinner gas gaps. These very thin and accurately defined gas gaps improve the timing resolution of the chamber, so the goal is to build an mRPC with the thinnest gaps to achieve the best possible timing resolution. Two different construction techniques have been employed to make two mRPCs. The first technique is to physically separate the gas gaps with sheets of glass that are .2mm thick. The second technique is to 3D print the layered gas gaps. A comparison of these mRPCs and their performances will be discussed and the latest data presented. This research was supported by US DOE MENP Grant DE-FG02-03ER41243.

  9. Space charge limited avalanche growth in multigap resistive plate chambers

    International Nuclear Information System (INIS)

    Akindinov, A.N.; Kaidalov, A.B.; Kisselev, S.M.; Alici, A.; Basile, M.; Cifarelli, L.; Anselmo, F.; Antonioli, P.; Romeo, G. Cara; Cindolo, F.; Baek, Y.; Kim, D.H.; Cosenza, F.; Caro, A. De; Pasquale, S. De; Bartolomeo, A. Di; Girard, M. Fusco; Guida, M.; Hatzifotiadou, D.; Kim, D.W.; Laurenti, G.; Lee, K.; Lee, S.C.; Lioublev, E.; Luvisetto, M.L.; Margotti, A.; Martemiyanov, A.N.; Nania, R.; Noferini, F.; Otiougova, P.; Pierella, F.; Polozov, P.A.; Scapparone, E.; Scioli, G.; Sellitto, S.B.; Smirnitski, A.V.; Tchoumakov, M.M.; Valenti, G.; Vicinanza, D.; Voloshin, K.G.; Williams, M.C.S.; Zagreev, B.V.; Zampolli, C.; Zichichi, A.

    2004-01-01

    Abstract The ALICE TOF array will be built using the Multigap Resistive Plate Chamber(MRPC) configured as a double stack. Each stack contains 5 gas gaps with width of 250 μm. There has been an intense R and D effort to optimise this new detector to withstand the problems connected with the high level of radiation at the LHC. One clear outcome of the R and D is that the growth of the gas avalanche is strongly affected by space charge. The effect of the space charge is a decrease in the rate of change in gain with electric field; this allows more stable operation of this detector. We have measured the gain as a function of the electric field and also measured the ratio of the fast charge to the total charge produced in the gas gap. It is well established that RPCs built with 250 μm gas gap have a much superior performance than 2 mm gaps; we discuss and compare the performance of 250 μm gap MRPCs with 2 mm gap RPCs to show the importance of space-charge limitation of avalanche growth. (orig.)

  10. A parallel plate avalanche chamber for relativistic heavy ions

    International Nuclear Information System (INIS)

    Burgei, R.

    1989-01-01

    In order to determine the interaction point of relativistic heavy ions in the Diogene target, we have built and tested an X-Y low pressure parallel plate avalanche chamber. It uses three thin metallized foils and is filled with isobutane. A preliminary study shows that it is the only detector with the required specifications: efficiency, accurate position determination and a small uniform amount of material for the particle beam to go through. The electronics system is designed for reliability, easy adjustments and high stability. The interaction point is given on delay-line read-out. This represents the optimum compromise between low price and good performance. Laboratory measurements of gain, efficiency and position accuracy are done with an alpha-particle source. Two of these detectors are working at the Saturne National Laboratory. They allow the trajectory of several tens of particles (among a million per second) to be reconstructed. With an argon beam at 400 MeV per nucleon, the position uncertainty in the target has been measured to be 0.5 mm (standard deviation). This uncertainty is 0.3 mm for each detector, with an efficiency of 94 per cent. Our set-up, which is now operational, improves the accuracy of the results and speed of analysis of Diogene experiments devoted to the study of central collisions between heavy ions [fr

  11. Monitoring the Resistive Plate Chambers in the Muon Spectrometer of ATLAS.

    CERN Document Server

    Al-Qahtani, Shaikha

    2017-01-01

    A software was developed to monitor the resistive plate chambers. The purpose of the program is to detect any weak or dead chambers and locate them for repair. The first use of the program was able to spot several chambers with problems to be investigated.

  12. Absorbed dose calibration factors for parallel-plate chambers in high energy photon beams

    International Nuclear Information System (INIS)

    McEwen, M.R.; Duane, S.; Thomas, R.A.S.

    2002-01-01

    An investigation was carried out into the performance of parallel-plate chambers in 60 Co and MV photon beams. The aim was to derive calibration factors, investigate chamber-to-chamber variability and provide much-needed information on the use of parallel-plate chambers in high-energy X-ray beams. A set of NE2561/NE2611 reference chambers, calibrated against the primary standard graphite calorimeter is used for the dissemination of absorbed dose to water. The parallel-plate chambers were calibrated by comparison with the NPL reference chambers in a water phantom. Two types of parallel-plate chamber were investigated - the NACP -02 and Roos and measurements were made at 60 C0 and 6 linac photon energies (6-19 MV). Calibration factors were derived together with polarity corrections. The standard uncertainty in the calibration of a chamber in terms of absorbed dose to water is estimated to be ±0.75%. The results of the polarity measurements were somewhat confusing. One would expect the correction to be small and previous measurements in electron beams have indicated that there is little variation between chambers of these types. However, some chambers gave unexpectedly large polarity corrections, up to 0.8%. By contrast the measured polarity correction for a NE2611 chamber was less than 0.13% at all energies. The reason for these large polarity corrections is not clear, but experimental error and linac variations have been ruled out. By combining the calibration data for the different chambers it was possible to obtain experimental k Q factors for the two chamber types. It would appear from the data that the variations between chambers of the same type are random and one can therefore define a generic curve for each chamber type. These are presented in Figure 1, together with equivalent data for two cylindrical chamber types - NE2561/NE2611 and NE2571. As can be seen, there is a clear difference between the curves for the cylindrical chambers and those for the

  13. Beam test results of a resistive plate chamber made of Chinese bakelites

    CERN Document Server

    Ying, J; Ban, Y; Liu Hong Tao; Zhu, Z M; Zhu, Z Y; Chen, T; Ma Jing Guo; Qian, S J

    2001-01-01

    The detailed beam test results of the first Chinese made avalanche mode resistive plate chamber are reported. The experimental set-ups at CERN GIF area are introduced. The detection efficiency, position resolution and time resolution of the chamber fulfil requirements as muon trigger for the future LHC experiments, while the rate capability is not good enough if the chamber is used at forward region. The applicability and the further possible improvements of the chamber are discussed. (12 refs).

  14. Resistive Plate Chamber Performance During the CMS Magnet Test Cosmic Challenge

    CERN Document Server

    Trentadue, R

    2008-01-01

    The CMS detector at the CERN Large Hadron Collider (LHC) is equipped with a redundant muon system based on Drift Tubes Chambers (barrel region) and Cathode Strip Chamber (endcap region), and Resistive Plate Chamber (RPC). During the summer and fall 2006 a first integrated test of an entire CMS slice was performed at the SX5 experimental surface hall. The RPC chambers were operated with cosmic rays. The results on the RPC performance are reported.

  15. Mechanisms Affecting Performance of the BaBar Resistive Plate Chambers and Searches for Remediation

    International Nuclear Information System (INIS)

    Lu, Changguo

    2003-01-01

    The BaBar experiment at PEPII relies on the Instrumentation of the Flux Return (IFR) for both muon identification and KL detection. The active detector is composed of Resistive Plate Chambers (RPC's) operated in streamer mode. Since the start of operation the RPC's have suffered persistent efficiency deterioration and dark current increase problems. The ''autopsy'' of bad BaBar RPC's revealed that in many cases uncured Linseed oil droplets had formed on the inner surface of the Bakelite plates, leading to current paths from oil ''stalagmites'' bridging the 2 mm gap. In this paper a possible model of this ''stalagmite'' formation and its effect on the dark current and efficiency of RPC chambers is presented. Laboratory test results strongly support this model. Based upon this model we are searching for solutions to eliminate the unfavorable effect of the oil stalagmites. The lab tests show that the stalagmite resistivity increases dramatically if exposed to the air, an observation that points to a possible way to remedy the damage and increase the efficiency. We have seen that flowing an oxygen gas mixture into the chamber helps to polymerize the uncured linseed oil. Consequently the resistivity of the bridged oil stalagmites increases, as does that of the oil coating on the frame edges and spacers, significantly reducing the RPC dark currents and low-efficiency regions. We have tested this idea on two chambers removed from BaBar because of their low efficiency and high dark current. These test results are reported in the paper, and two other remediation methods also mentioned. We continue to study this problem, and try to find new treatments with permanent improvement

  16. Space-charge limitation of avalanche growth in narrow-gap resistive plate chambers

    CERN Document Server

    Williams, M C S

    2004-01-01

    A big advance in resistive plate chamber technology happened in 1996 with the advent of the multigap resistive plate chamber (MRPC). The MRPC allows us to easily construct detectors with many small gas gaps and thus we obtain good timing together with high detection efficiency. Using this technology, it is now common to build detectors with gas gaps of 200-300 mum in width. This paper examines space-charge limited avalanche growth; this becomes a dominant effect for narrow gap resistive plate chambers. This effect controls gas gain and explains the reason for the excellent behaviour of MRPCs built with this gas gap.

  17. Progresses in the simulation of Resistive Plate Chambers in avalanche mode

    Energy Technology Data Exchange (ETDEWEB)

    Abbrescia, M.; Colaleo, A.; Iaselli, G.; Loddo, F.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Pugliese, G.; Ranieri, A.; Romano, F.; Altieri, S.; Bruno, G.; Gianini, G.; Ratti, S.P.; Viola, L.; Vitulo, P

    1999-08-01

    New results about the simulation of Resistive Plate Chambers are reported; particular emphasis is put in the understanding of charge spectra in regions where deviations from the pure avalanche mode of operation can be present.

  18. The simulation of resistive plate chambers in avalanche mode: charge spectra and efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Abbrescia, M. E-mail: Marcello.abbrescia@ba.infn.it; Colaleo, A.; Iaselli, G.; Loddo, F.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Pugliese, G.; Ranieri, A.; Romano, F.; Altieri, S.; Bruno, G.; Gianini, G.; Ratti, S.P.; Viola, L.; Vitulo, P

    1999-07-21

    A model to simulate the avalanche formation process and the induced signal in a Resistive Plate Chamber is presented. A first investigation of the effects of various parameters on the performance of this detector is reported. (author)

  19. First results on irradiation of ceramic parallel plate chambers with gammas and neutrons

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, Gy.L.; Bizzeti, A.; Choumilov, E.; Civinini, C.; Dajko, G.; D'Alessandro, R.; Fenyvesi, A.; Ferrando, A.; Fouz, M.C.; Iglesias, A.; Ivochkin, V.; Josa, M.I.; Malinin, A.; Meschini, M.; Molnar, J.; Pojidaev, V.; Salicio, J.M.; Tanko, L.; Vesztergombi, G.

    1996-01-01

    Ceramic parallel plate chambers were irradiated with gamma rays and neutrons. Results on radiation resistance are presented after 60 Mrad gamma and 0.5.10 16 neutrons per cm 2 irradiation of the detector surface. Results of activation analysis of chambers made of two different ceramic materials are also presented. (orig.)

  20. Flow of nanofluid past a Riga plate

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Adeel, E-mail: adeelahmed@comsats.edu.pk [Department of Mathematics, COMSATS Institute of Information Technology, Park Road, Chak Shahzad, 44000 Islamabad (Pakistan); Laboratoire J.A. Dieudonné, Université de Nice Sophia Antipolis, Parc Valrose, 06108 Nice (France); Asghar, Saleem [Department of Mathematics, COMSATS Institute of Information Technology, Park Road, Chak Shahzad, 44000 Islamabad (Pakistan); Department of Mathematics, King Abdul Aziz University, Jeddah (Saudi Arabia); Afzal, Sumaira [Department of Mathematics, COMSATS Institute of Information Technology, Park Road, Chak Shahzad, 44000 Islamabad (Pakistan)

    2016-03-15

    This paper studies the mixed convection boundary layer flow of a nanofluid past a vertical Riga plate in the presence of strong suction. The mathematical model incorporates the Brownian motion and thermophoresis effects due to nanofluid and the Grinberg-term for the wall parallel Lorentz force due to Riga plate. The analytical solution of the problem is presented using the perturbation method for small Brownian and thermophoresis diffusion parameters. The numerical solution is also presented to ensure the reliability of the asymptotic method. The comparison of the two solutions shows an excellent agreement. The correlation expressions for skin friction, Nusselt number and Sherwood number are developed by performing linear regression on the obtained numerical data. The effects of nanofluid and the Lorentz force due to Riga plate, on the skin friction are discussed. - Highlights: • Mixed convection flow of a nanofluid past a vertical Riga plate. • The Brownian motion and thermophoresis effects due to nanofluid are incorporated. • Grinberg-term represents the wall parallel Lorentz force due to Riga plate. • The correlation expressions for skin friction, Nusselt and Sherwood numbers are developed. • The effects of nanofluid and the Lorentz force on the skin friction are discussed.

  1. Evaluation of dose distributions in gamma chamber using glass plate detector

    Directory of Open Access Journals (Sweden)

    Narayan Pradeep

    2008-01-01

    Full Text Available A commercial glass plate of thickness 1.75 mm has been utilized for evaluation of dose distributions inside the irradiation volume of gamma chamber using optical densitometry technique. The glass plate showed linear response in the dose range 0.10 Kilo Gray (kGy to 10 kGy of cobalt-60 gamma radiation with optical sensitivity 0.04 Optical Density (OD /kGy. The change in the optical density at each identified spatial dose matrix on the glass plate in relation to the position in the irradiation volume has been presented as dose distributions inside the gamma chamber. The optical density changes have been graphically plotted in the form of surface diagram of color washes for different percentage dose rate levels as isodose distributions in gamma chamber. The variation in dose distribution inside the gamma chamber unit, GC 900, BRIT India make, using this technique has been observed within ± 15%. This technique can be used for routine quality assurances and dose distribution validation of any gamma chamber during commissioning and source replacement. The application of commercial glass plate for dose mapping in gamma chambers has been found very promising due to its wider dose linearity, quick measurement, and lesser expertise requirement in application of the technique.

  2. Project, construction and calibration of parallel plate ionization chambers for x-radiation

    International Nuclear Information System (INIS)

    Albuquerque, M.P.P.

    1989-01-01

    Two pairs of parallel-plate ionization chambers were projected and constructed. In each pair one of the chambers has a collecting electrode and a guard ring made of graphite and the other, of aluminium. The difference between both pairs is that in only one case screws were used to fix the chamber components. The chambers are made of Lucite with aluminized Mylar entrance windows; they have circular form and are unsealed. All chamber components are easily available. The main chamber characteristics were determined, applying the tests of current leakage, repetitively and long term stability. The energy and angular dependence, and the polarity effect were also studied, obtaining the saturation curves and determining the build-up effect for gamma radiation detection. The chambers were calibrated with low and intermediate energy X-radiation, gamma radiation of sup(60)Co an sup(137)Cs, and beta radiation of sup(90)Sr + sup(90)Y. The obtained results show the viability of utilization of these chambers in radiation dosimetry and the results were compared with those of imported commercial ionization chambers of the secondary standard type. The great difference between the energy dependence of the chambers according to the collecting electrode material, allowed the formation of a Tandem system (constituted by a chamber pair A, C), for the determination of the effective energy and the exposure rate in air of unknown X-radiation fields, in the case of low intermediate energy ranges. (author)

  3. Local and global performance of double-gap resistive plate chambers operated in avalanche mode

    Energy Technology Data Exchange (ETDEWEB)

    Abbrescia, M.; Colaleo, A.; Iaselli, G.; Loddo, F.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Pugliese, G.; Ranieri, A.; Romano, F.; Altieri, S.; Belli, G.; Bruno, G.; Gianini, G.; Ratti, S.P.; Viola, L.; Vitulo, P.; Sergueev, S

    1999-09-21

    Two large double-gap resistive plate chambers, with 2 and 3 mm gap widths, were tested to study their response uniformity when operated in avalanche mode. The effects of mechanical tolerances and the presence of the spacers is thoroughly examined. Results on efficiency and time resolution are presented. We find that average performance and response uniformity over the whole chamber surface are fully adequate to the requirements of future collider experiments. (author)

  4. Microscopic Holography for flow over rough plate

    Science.gov (United States)

    Talapatra, Siddharth; Hong, Jiarong; Lu, Yuan; Katz, Joseph

    2008-11-01

    Our objective is to measure the near wall flow structures in a turbulent channel flow over a rough wall. In-line microscopic holographic PIV can resolve the 3-D flow field in a small sample volume, but recording holograms through a rough surface is a challenge. To solve this problem, we match the refractive indices of the fluid with that of the wall. Proof of concept tests involve an acrylic plate containing uniformly distributed, closely packed 0.45mm high pyramids with slope angle of 22^^o located within a concentrated sodium iodide solution. Holograms recorded by a 4864 x 3248 pixel digital camera at 10X magnification provide a field of view of 3.47mm x 2.32mm and pixel resolution of 0.714 μm. Due to index matching, reconstructed seed particles can be clearly seen over the entire volume, with only faint traces with the rough wall that can be removed. Planned experiments will be performed in a 20 x 5 cm rectangular channel with the top and bottom plates having the same roughness as the sample plate.

  5. Mixed convection flow past a horizontal plate

    Directory of Open Access Journals (Sweden)

    Savić Lj.

    2005-01-01

    Full Text Available The mixed convection flow past a horizontal plate being aligned through a small angle of attack to a uniform free stream will be considered in the limit of large Reynolds number and small Richardson number. Even a small angle of inclination of the wake is sufficient for the buoyancy force to accelerate the flow in the wake which causes a velocity overshoot in the wake. Moreover a hydrostatic pressure difference across the wake induces a correction to the potential flow which influences the inclination of the wake. Thus the wake and the correction of the potential flow have to be determined simultaneously. However, it turns out that solutions exist only if the angle of attack is sufficiently large. Solutions are computed numerically and the influence of the buoyancy on the lift coefficient is determined.

  6. Performance of a parallel plate ionization chamber in beta radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Antonio, Patricia L.; Caldas, Linda V.E., E-mail: patrilan@ipen.b, E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    A homemade parallel plate ionization chamber with graphite collecting electrode, and developed for use in mammography beams, was tested in relation to its usefulness in beta radiation dosimetry at the Calibration Laboratory of IPEN. Characterization tests of this ionization chamber were performed, using the Sr-90 + Y-90, Kr-85 and Pm-147 sources of a beta secondary standard system. The results of saturation, leakage current, stabilization time, response stability, linearity, angular dependence, and calibration coefficients are within the recommended limits of international recommendations that indicate that this chamber may be used for beta radiation dosimetry. (author)

  7. Test and characterization of multigap resistive plate chambers for the EEE project

    CERN Document Server

    Bossini, E

    2016-01-01

    The Extreme Energy Events project is based on the deployment of cosmic-ray telescopes in Italian high schools with the active contribution of students and teachers. Each telescope is made by three Multigap Resistive Plate Chambers readout by strips. With around 50 telescopes already built and others under construction, specific systems to test and characterize the chambers are needed. In this article I will present a flexible and software-configurable solution to perform chamber efficiency studies with a set of scintillators and hardware to automatically scan detector strips to identify electrical issues. Both systems can provide accurate information but at the same time they can be easily operated by students.

  8. Performance of a parallel plate ionization chamber in beta radiation dosimetry

    International Nuclear Information System (INIS)

    Antonio, Patricia L.; Caldas, Linda V.E.

    2011-01-01

    A homemade parallel plate ionization chamber with graphite collecting electrode, and developed for use in mammography beams, was tested in relation to its usefulness in beta radiation dosimetry at the Calibration Laboratory of IPEN. Characterization tests of this ionization chamber were performed, using the Sr-90 + Y-90, Kr-85 and Pm-147 sources of a beta secondary standard system. The results of saturation, leakage current, stabilization time, response stability, linearity, angular dependence, and calibration coefficients are within the recommended limits of international recommendations that indicate that this chamber may be used for beta radiation dosimetry. (author)

  9. Improvement of Swirl Chamber Structure of Swirl-Chamber Diesel Engine Based on Flow Field Characteristics

    Directory of Open Access Journals (Sweden)

    Wenhua Yuan

    2014-10-01

    Full Text Available In order to improve combustion characteristic of swirl chamber diesel engine, a simulation model about a traditional cylindrical flat-bottom swirl chamber turbulent combustion diesel engine was established within the timeframe of the piston motion from the bottom dead centre (BDC to the top dead centre (TDC with the fluent dynamic mesh technique and flow field vector of gas in swirl chamber and cylinder; the pressure variation and temperature variation were obtained and a new type of swirl chamber structure was proposed. The results reveal that the piston will move from BDC; air in the cylinder is compressed into the swirl chamber by the piston to develop a swirl inside the chamber, with the ongoing of compression; the pressure and temperature are also rising gradually. Under this condition, the demand of diesel oil mixing and combusting will be better satisfied. Moreover, the new structure will no longer forma small fluid retention zone at the lower end outside the chamber and will be more beneficial to the mixing of fuel oil and air, which has presented a new idea and theoretical foundation for the design and optimization of swirl chamber structure and is thus of good significance of guiding in this regard.

  10. Effect of temperature on the multi-gap resistive plate chamber operation

    International Nuclear Information System (INIS)

    Zhao, Y.E.; Wang, X.L.; Liu, H.D.; Chen, H.F.; Li, C.; Wu, J.; Xu, Z.Z.; Shao, M.; Zeng, H.; Zhou, Y.

    2005-01-01

    In order to obtain a quantitative understanding of the influence of temperature on the multi-gap resistive plate chamber (MRPC) operation, we tested the performance of a 6-gap, 6.1x20 cm 2 active area MRPC with cosmic rays at different temperatures. Results of measurements of noise rate, dark current and detection efficiency are presented

  11. Electron equilibrium for parallel plate ionization chambers in gamma radiation fields

    International Nuclear Information System (INIS)

    Caldas, L.; Albuquerque, M. da P.P.

    1989-08-01

    Parallel plate ionization chambers, designed and constructed for use in low energy X-radiation fields, were tested in gamma radiation beams ( 6 Co and 137 Cs) of two different Calibration Laboratories, in order to study the electron equilibrium occurrence and to verify the possibility of their use for the detection of the kind of radiation too. (author) [pt

  12. Calorimeter detector consisting of a KMgF3 scintillator and parallel-plate avalanche chamber

    International Nuclear Information System (INIS)

    Buzulutskov, A.F.; Turchanovich, L.K.; Vasil'chenko, V.G.

    1989-01-01

    Scintillations of a KMgF 3 crystal have been detected in the parallel-plate avalanche chamber with a TEA gaseous photocathode, the scintillation signal is shown to be much higher than the direct ionization one. The characteristic properties of the calorimeters on the basis of such structure with electrical and optical readout are discussed. 10 refs.; 4 figs

  13. Properties of a six-gap timing resistive plate chamber with strip readout

    International Nuclear Information System (INIS)

    Ammosov, V.V.; Gapienko, V.A.; Semak, A.A.; Sviridov, Yu.M.; Zaets, V.G.; Gavrishchuk, O.P.; Kuz'min, N.A.; Sychkov, S.Ya.; Usenko, E.A.; Yukaev, A.I.

    2009-01-01

    Six-gap glass timing resistive plate chamber with strip readout was tested using IHEP U-70 PS test beam. The time resolution of ∼ 45 ps at efficiency larger than 98% was achieved. Position resolution along strip was estimated to be ∼1 cm

  14. Measurement of the spark probability in single gap parallel plate chambers

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, Gy.L.; Choumilov, E.; Civinini, C.; Dalla Santa, F.; D'Alessandro, R.; Ferrando, A.; Fouz, M.C.; Golovkin, V.; Kholodenko, A.; Iglesias, A.; Ivochkin, V.; Josa, M.I.; Malinin, A.; Meschini, M.; Misyura, S.; Pojidaev, V.; Salicio, J.M.

    1996-01-01

    We present results on the measurements of the spark probability with CO 2 and CF 4 /CO 2 (80/20) mixture, at atmospheric pressure, using 1.5 mm gas gap parallel plate chambers, working at a gas gain ranging from 4.5 x 10 2 to 3.3 x 10 4 . (orig.)

  15. Plate-out rates of radon progeny and particles in a spherical chamber

    International Nuclear Information System (INIS)

    Cheng, Y.S.; Chen, B.T.

    1990-01-01

    In indoor and mining environments, deposition or ''plate-out'' of radon progeny onto walls occurs simultaneously with attachment of the radon progeny to airborne particles. Attachment and plate-out processes affect the atmosphere in which radon exposures takes place by reducing concentrations and shifting activity size distributions. Both processes have important consequences in determining the deposition pattern and initial dose of inhaled radon progeny. Theoretical deposition models show that turbulence and natural convection in a room are the major factors that influence plate-out rates. Here we describe plate-out measurements for radon progeny and aerosol particles in a spherical chamber under controlled laboratory conditions. The temperature and velocity profiles in still and turbulent air were monitored. A 161-liter spherical aluminum chamber was used to study the mixing. During mixing, air velocity was detected when rotational speeds were higher than 500 rpm. Monodisperse silver aerosols and polystyrene latex particles in the size range of 5 nm to 2 μm were used in the deposition study. Radon-220 progeny were generated by passing Rn-220 gas into the chamber and letting the gas decay into 212 Pb. The deposition rates of the particles and radon progeny ( 212 Pb) in the chamber were determined by monitoring the concentration decay of the aerosol as a function of time

  16. New gas mixtures for Resistive Plate Chambers operated in avalanche mode

    Energy Technology Data Exchange (ETDEWEB)

    Abbrescia, M [Dipartimento Interateneo di Fisica, Universita di Bari and sezione INFN, via Amendola 173, I-70126 Bari (Italy); Cassano, V; Nuzzo, S; Piscitelli, G; Vadruccio, D; Zaza, S [Dipartimento Interateneo di Fisica, Universita di Bari and sezione INFN, via Amendola 173, I-70126 Bari (Italy)

    2012-01-01

    The possibility of using gas mixtures containing Helium, to overcome some of the problems encountered with standard gas mixture employed up to now for Resistive Plate Chambers, is studied here. New and interesting experimental results are reported, opening a possible original path of investigation in this field.

  17. Performance of Resistive Plate Chambers installed during the first long shutdown of the CMS experiment

    CERN Document Server

    Shopova, M.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Sultanov, G.; Rodozov, M.; Stoykova, S.; Assran, Y.; Sayed, A.; Radi, A.; Aly, S.; Singh, G.; Abbrescia, M.; Iaselli, G.; Maggi, M.; Pugliese, G.; Verwilligen, P.; Van Doninck, W.; Colafranceschi, S.; Sharma, A.; Benussi, L.; Bianco, S.; Piccolo, D.; Primavera, F.; Cimmino, A.; Crucy, S.; Rios, A.A.O.; Tytgat, M.; Zaganidis, N.; Gul, M.; Fagot, A.; Bhatnagar, V.; Singh, J.; Kumari, R.; Mehta, A.; Ahmad, A.; Awan, I.M.; Shahzad, H.; Hoorani, H.; Asghar, M.I.; Muhammad, S.; Ahmed, W.; Shah, M.A.; Cho, S.W.; Choi, S.Y.; Hong, B.; Kang, M.H.; Lee, K.S.; Lim, J.H.; Park, S.K.; Kim, M.S.; Laktineh, I.B.; Lagarde, F.; Gouzevitch, M.; Grenier, G.; Pedraza, I.; Bernardino, S. Carpinteyro; Estrada, C. Uribe; Carrillo Moreno, S.; Valencia, F. Vazquez; Pant, L.M.; Buontempo, S.; Cavallo, N.; Fabozzi, F.; Orso, I.; Lista, L.; Meola, S.; Merola, M.; Paolucci, P.; Thyssen, F.; Lanza, G.; Esposito, M.; Braghieri, A.; Magnani, A.; Riccardi, C.; Salvini, P.; Vai, I.; Vitulo, P.; Montagna, P.; Ban, Y.; Qian, S.J.; Choi, M.; Choi, Y.; Goh, J.; Kim, D.; Dimitrov, A.; Litov, L.; Petkov, P.; Pavlov, B.; Bagaturia, I.; Lomidze, D.; Avila, C.; Cabrera, A.; Sanabria, J.C.; Crotty, I.; Vaitkus, J.

    2016-01-01

    The CMS experiment, located at the CERN Large Hadron Collider, has a redundant muon system composed by three different detector technologies: Cathode Strip Chambers (in the forward regions), Drift Tubes (in the central region) and Resistive Plate Chambers (both its central and forward regions). All three are used for muon reconstruction and triggering. During the first long shutdown (LS1) of the LHC (2013-2014) the CMS muon system has been upgraded with 144 newly installed RPCs on the forth forward stations. The new chambers ensure and enhance the muon trigger efficiency in the high luminosity conditions of the LHC Run2. The chambers have been successfully installed and commissioned. The system has been run successfully and experimental data has been collected and analyzed. The performance results of the newly installed RPCs will be presented.

  18. Studies of gaseous multiplication coefficient in isobutane using a resistive plate chamber

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Josemary A.C.; Botelho, Suzana; Tobias, Carmen C.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Pontificia Univ. Catolica de Sao Paulo (PUC/SP), SP (Brazil); Lima, Iara B.; Vivaldini, Tulio C. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Ridenti, Marco A.; Pascholati, Paulo R. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Fisica. Lab. do Acelerador Linear; Fonte, Paulo; Mangiarotti, Alessio [Universidade de Coimbra (Portugal). Dept. de fisica. Lab. de Instrumentacao e Fisica Experimental de Particulas

    2009-07-01

    Full text: Due to the increasing demands concerning High Energy Physics, Nuclear Medicine and other Nuclear Applications about gaseous detectors operating in high electric fields, many efforts have been done about the choice of filling gases that fulfill these requirements. In this context, the electron transport parameters in gases, as the gaseous multiplication coefficient, play an important role not only for detector design but also for simulation and modeling of discharges, allowing the validation of electron impact cross-sections. In the present work the preliminary measurements of gaseous multiplication coefficient, as function of the reduced electric field (from 36V/cm.Torr until 93V/cm.Torr), for isobutane are presented. Among several filling gases, isobutane is widely used in resistive plate chambers RPCs, and other gaseous detectors, due to its timing properties. Although its characteristics, there is a lack of swarm parameters data in literature for this gas, mainly at high electric fields. The experimental method used is based on the Pulsed Townsend technique, which follows from Townsend equation solution for a uniform electric field. Considering the ratio between the current (I), measured in avalanche mode, and the primary ionization current (I{sub 0}), the effective multiplication coefficient can be determined, since alpha = d{sup -1}ln(I/I{sub 0}), where d is the gap between the electrodes. In our configuration, the experimental setup consists of two parallel plates enclosure in a stainless steel chamber at gas flow regime. The anode, is made of a high resistivity (2.10{sup 12}{omega}.cm) glass (3mm thick and 14mm diameter), while the cathode is of aluminium (40mm diameter). Primary electrons are produced by irradiating the cathode with a nitrogen laser (LTB MNL200-LD) and are accelerated toward the anode by means of a high voltage power supply (Bertan 225-30). In order to validate the technique and to analyze effects of non-uniformity, results for

  19. Long-term performance of double gap resistive plate chambers under gamma irradiation

    CERN Document Server

    Abbrescia, M; Guarrasi, L; Iaselli, Giuseppe; Loddo, F; Maggi, M; Marangelli, B; Natali, S; Nuzzo, S; Pugliese, G; Ranieri, A; Romano, F; Altieri, S; Belli, G; Bruno, G; Gianini, G; Ratti, S P; Riccardi, C; Torre, P; Viola, L; Vitulo, P

    2002-01-01

    In this paper, we describe a dedicated test to study possible long- term aging effects on Resistive Plate Chambers (RPCs). A double gap detector was operated under gamma irradiation for a period approximately equal to 10 years of LHC in the CMS-barrel region: an integrated dose of about 1.6 Gy and a total charge of about 0.05 C/cm /sup 2/ gap were accumulated on the chamber. The results show no relevant aging effect. Also the RPC sensitivity to /sup 60/Co gamma energies is measured. (9 refs).

  20. Comparison of CMS Resistive Plate Chambers performance during LHC RUN-1 and RUN-2

    CERN Document Server

    INSPIRE-00207984

    2016-01-01

    The Resistive Plate Chambers detector system at the CMS experiment at the LHC provides robustness and redundancy to the muon trigger. A total of 1056 double-gap chambers cover the pseudo-rapidity region < 1.6. The main detector parameters and environmental conditions are constantly and closely monitored to achieve operational stability and high quality data in the harsh conditions of the second run period of the LHC with center-of-mass energy of 13 TeV. First results of overall detector stability with 2015 data and comparisons with data from the LHC RUN-1 period at 8 TeV are presented.

  1. Comparison of CMS Resistive Plate Chambers performance during LHC RUN-1 and RUN-2

    CERN Document Server

    Shah, Mehar Ali

    2016-01-01

    The Resistive Plate Chambers detector system at the CMS experiment at the LHC provides robustness and redundancy to the muon trigger. A total of 1056 double-gap chambers cover the pseudo-rapidity region lt 1.6. The main detector parameters and environmental conditions are constantly and closely monitored to achieve operational stability and high quality data in the harsh conditions of the second run period of the LHC with center-of-mass energy of 13 TeV. First results of overall detector stability with 2015 data and comparisons with data from the LHC RUN-1 period at 8 TeV are presented.

  2. Long-term performance of double gap resistive plate chambers under gamma irradiation

    International Nuclear Information System (INIS)

    Abbrescia, M.; Colaleo, A.; Guarrasi, L.; Iaselli, G.; Loddo, F.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Pugliese, G.; Ranieri, A.; Romano, F.; Altieri, S.; Belli, G.; Bruno, G.; Gianini, G.; Ratti, S.P.; Riccardi, C.; Torre, P.; Viola, L.; Vitulo, P.

    2002-01-01

    In this paper, we describe a dedicated test to study possible long-term aging effects on Resistive Plate Chambers (RPCs). A double gap detector was operated under gamma irradiation for a period approximately equal to 10 years of LHC in the CMS-barrel region: an integrated dose of about 1.6 Gy and a total charge of about 0.05 C/cm 2 gap were accumulated on the chamber. The results show no relevant aging effect. Also the RPC sensitivity to 60 Co gamma energies is measured

  3. Long-term performance of double gap resistive plate chambers under gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Abbrescia, M.; Colaleo, A.; Guarrasi, L.; Iaselli, G.; Loddo, F.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Pugliese, G. E-mail: gabriella.pugliese@ba.infn.it; Ranieri, A.; Romano, F.; Altieri, S.; Belli, G.; Bruno, G.; Gianini, G.; Ratti, S.P.; Riccardi, C.; Torre, P.; Viola, L.; Vitulo, P

    2002-01-21

    In this paper, we describe a dedicated test to study possible long-term aging effects on Resistive Plate Chambers (RPCs). A double gap detector was operated under gamma irradiation for a period approximately equal to 10 years of LHC in the CMS-barrel region: an integrated dose of about 1.6 Gy and a total charge of about 0.05 C/cm{sup 2} gap were accumulated on the chamber. The results show no relevant aging effect. Also the RPC sensitivity to {sup 60}Co gamma energies is measured.

  4. Study of the effect of water vapor on a resistive plate chamber with glass electrodes

    CERN Document Server

    Sakai, H H; Teramoto, Y; Nakano, E E; Takahashi, T T

    2002-01-01

    We studied the effects of water vapor on the efficiencies of resistive plate chambers with glass electrodes, operated in the streamer mode. With moisture in the chamber gas that has freon as a component (water vapor approx 1000 ppm), a decrease in the efficiency (approx 20%) has been observed after operating for a period of several weeks to a few months. From our study, the cause of the efficiency decrease was identified as a change on the cathode surface. In addition, a recovery method was found: flushing for 1 day with argon bubbled through water containing >=3% ammonia, followed by a few weeks of training with dry gas.

  5. Latest results on the performance of the multigap resistive plate chamber used for the ALICE TOF

    International Nuclear Information System (INIS)

    Akindinov, A.N.; Alici, A.; Anselmo, F.

    2004-01-01

    For the identification of particles in the momentum range 0.5-2.5GeV/c, the ALICE experiment uses a Time Of Flight array consisting of Multigap Resistive Plate Chambers (MRPC) in the form of long strips. The design of the detector elements is as follows : double stack MRPCs with glass resistive plates and 5 gas gaps of 250μm per stack. The latest results on the performance of these MRPCs are presented. Typical values of time resolution σ are better than 50ps, with an efficiency of 99.9% and a long, more than 1.5kV, streamer-free plateau

  6. Latest results on the performance of the multigap resistive plate chamber used for the ALICE TOF

    CERN Document Server

    Akindinov, A; Anselmo, F; Antonioli, P; Basile, M; Cara Romeo, G; Cifarelli, Luisa; Cindolo, F; Cosenza, F; D'Antone, I; De Caro, A; De Pasquale, S; Di Bartolomeo, A; Fusco-Girard, M; Golovine, V; Guerzoni, M; Guida, M; Hatzifotiadou, D; Kaidalov, A B; Kim, D H; Kim, D W; Kisselev, S M; Laurenti, G; Lioublev, E; Lee, K; Lee, S C; Luvisetto, M L; Margotti, A; Martemyanov, A N; Massera, F; Meneghini, S; Michinelli, R; Nania, R; Otiougova, P; Pancaldi, G; Pesci, A; Pilastrini, R; Pinazza, O; Polozov, P A; Rizzi, M; Scapparone, E; Scioli, G; Sellitto, S B; Semeria, F; Serra, S; Smirnitsky, A V; Tchoumakov, M M; Ugolini, E; Usenko, E; Valenti, G; Voloshin, K G; Williams, M C S; Zagreev, B V; Zampolli, C; Zichichi, A; Zucchini, A; Zuffa, M

    2004-01-01

    For the identification of particles in the momentum range 0.5-2.5 GeV /c, the ALICE experiment uses a Time Of Flight array consisting of Multigap Resistive Plate Chambers (MRPC) in the form of long strips. The design of the detector elements is as follows: double stack MRPCs with glass resistive plates and 5 gas gaps of 250 mum per stack. The latest results on the performance of these MRPCs are presented. Typical values of time resolution sigma are better than 50 ps, with an efficiency of 99.9% and a long, more than 1.5kV, streamer-free plateau.

  7. High-Rate Glass Resistive Plate Chambers For LHC Muon Detectors Upgrade

    CERN Document Server

    Laktineh, I; Cauwenbergh, S; Combret, C; Crotty, I; Haddad, Y; Grenier, G; Guida, R; Kieffer, R; Lumb, N; Mirabito, L; Schirra, F; Seguin, N; Tytgat, M; Van der Donckt, M; Wang, Y; Zaganidis, N

    2012-01-01

    The limitation of the detection rate of standard bakelite resistive plate chambers (RPC) used as muon detector in LHC experiments is behind the absence of such detectors in the high TJ regions in both CMS and ATLAS detectors. RPCs made with low resistivity glass plates (10ID O.cm) could be an adequate solution to equip the high TJ regions extending thus both the trigger efficiency and the physics performance. Different beam tests with single and multi-gap configurations using the new glass have shown that such detectors can operate at few thousands Hzlcm2 with high efficiency( > 90%).

  8. Performance Study of the CMS Barrel Resistive Plate Chambers with Cosmic Rays

    CERN Document Server

    Chatrchyan, S; Sirunyan, A M; Adam, W; Arnold, B; Bergauer, H; Bergauer, T; Dragicevic, M; Eichberger, M; Erö, J; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kastner, K; Krammer, M; Liko, D; Magrans de Abril, I; Mikulec, I; Mittermayr, F; Neuherz, B; Oberegger, M; Padrta, M; Pernicka, M; Rohringer, H; Schmid, S; Schöfbeck, R; Schreiner, T; Stark, R; Steininger, H; Strauss, J; Taurok, A; Teischinger, F; Themel, T; Uhl, D; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C E; Chekhovsky, V; Dvornikov, O; Emeliantchik, I; Litomin, A; Makarenko, V; Marfin, I; Mossolov, V; Shumeiko, N; Solin, A; Stefanovitch, R; Suarez Gonzalez, J; Tikhonov, A; Fedorov, A; Karneyeu, A; Korzhik, M; Panov, V; Zuyeuski, R; Kuchinsky, P; Beaumont, W; Benucci, L; Cardaci, M; De Wolf, E A; Delmeire, E; Druzhkin, D; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Adler, V; Beauceron, S; Blyweert, S; D'Hondt, J; De Weirdt, S; Devroede, O; Heyninck, J; Kalogeropoulos, A; Maes, J; Maes, M; Mozer, M U; Tavernier, S; Van Doninck, W; Van Mulders, P; Villella, I; Bouhali, O; Chabert, E C; Charaf, O; Clerbaux, B; De Lentdecker, G; Dero, V; Elgammal, S; Gay, A P R; Hammad, G H; Marage, P E; Rugovac, S; Vander Velde, C; Vanlaer, P; Wickens, J; Grunewald, M; Klein, B; Marinov, A; Ryckbosch, D; Thyssen, F; Tytgat, M; Vanelderen, L; Verwilligen, P; Basegmez, S; Bruno, G; Caudron, J; Delaere, C; Demin, P; Favart, D; Giammanco, A; Grégoire, G; Lemaitre, V; Militaru, O; Ovyn, S; Piotrzkowski, K; Quertenmont, L; Schul, N; Beliy, N; Daubie, E; Alves, G A; Pol, M E; Souza, M H G; Carvalho, W; De Jesus Damiao, D; De Oliveira Martins, C; Fonseca De Souza, S; Mundim, L; Oguri, V; Santoro, A; Silva Do Amaral, S M; Sznajder, A; Fernandez Perez Tomei, T R; Ferreira Dias, M A; Gregores, E M; Novaes, S F; Abadjiev, K; Anguelov, T; Damgov, J; Darmenov, N; Dimitrov, L; Genchev, V; Iaydjiev, P; Piperov, S; Stoykova, S; Sultanov, G; Trayanov, R; Vankov, I; Dimitrov, A; Dyulendarova, M; Kozhuharov, V; Litov, L; Marinova, E; Mateev, M; Pavlov, B; Petkov, P; Toteva, Z; Chen, G M; Chen, H S; Guan, W; Jiang, C H; Liang, D; Liu, B; Meng, X; Tao, J; Wang, J; Wang, Z; Xue, Z; Zhang, Z; Ban, Y; Cai, J; Ge, Y; Guo, S; Hu, Z; Mao, Y; Qian, S J; Teng, H; Zhu, B; Avila, C; Baquero Ruiz, M; Carrillo Montoya, C A; Gomez, A; Gomez Moreno, B; Ocampo Rios, A A; Osorio Oliveros, A F; Reyes Romero, D; Sanabria, J C; Godinovic, N; Lelas, K; Plestina, R; Polic, D; Puljak, I; Antunovic, Z; Dzelalija, M; Brigljevic, V; Duric, S; Kadija, K; Morovic, S; Fereos, R; Galanti, M; Mousa, J; Papadakis, A; Ptochos, F; Razis, P A; Tsiakkouri, D; Zinonos, Z; Hektor, A; Kadastik, M; Kannike, K; Müntel, M; Raidal, M; Rebane, L; Anttila, E; Czellar, S; Härkönen, J; Heikkinen, A; Karimäki, V; Kinnunen, R; Klem, J; Kortelainen, M J; Lampén, T; Lassila-Perini, K; Lehti, S; Lindén, T; Luukka, P; Mäenpää, T; Nysten, J; Tuominen, E; Tuominiemi, J; Ungaro, D; Wendland, L; Banzuzi, K; Korpela, A; Tuuva, T; Nedelec, P; Sillou, D; Besancon, M; Chipaux, R; Dejardin, M; Denegri, D; Descamps, J; Fabbro, B; Faure, J L; Ferri, F; Ganjour, S; Gentit, F X; Givernaud, A; Gras, P; Hamel de Monchenault, G; Jarry, P; Lemaire, M C; Locci, E; Malcles, J; Marionneau, M; Millischer, L; Rander, J; Rosowsky, A; Rousseau, D; Titov, M; Verrecchia, P; Baffioni, S; Bianchini, L; Bluj, M; Busson, P; Charlot, C; Dobrzynski, L; Granier de Cassagnac, R; Haguenauer, M; Miné, P; Paganini, P; Sirois, Y; Thiebaux, C; Zabi, A; Agram, J L; Besson, A; Bloch, D; Bodin, D; Brom, J M; Conte, E; Drouhin, F; Fontaine, J C; Gelé, D; Goerlach, U; Gross, L; Juillot, P; Le Bihan, A C; Patois, Y; Speck, J; Van Hove, P; Baty, C; Bedjidian, M; Blaha, J; Boudoul, G; Brun, H; Chanon, N; Chierici, R; Contardo, D; Depasse, P; Dupasquier, T; El Mamouni, H; Fassi, F; Fay, J; Gascon, S; Ille, B; Kurca, T; Le Grand, T; Lethuillier, M; Lumb, N; Mirabito, L; Perries, S; Vander Donckt, M; Verdier, P; Djaoshvili, N; Roinishvili, N; Roinishvili, V; Amaglobeli, N; Adolphi, R; Anagnostou, G; Brauer, R; Braunschweig, W; Edelhoff, M; Esser, H; Feld, L; Karpinski, W; Khomich, A; Klein, K; Mohr, N; Ostaptchouk, A; Pandoulas, D; Pierschel, G; Raupach, F; Schael, S; Schultz von Dratzig, A; Schwering, G; Sprenger, D; Thomas, M; Weber, M; Wittmer, B; Wlochal, M; Actis, O; Altenhöfer, G; Bender, W; Biallass, P; Erdmann, M; Fetchenhauer, G; Frangenheim, J; Hebbeker, T; Hilgers, G; Hinzmann, A; Hoepfner, K; Hof, C; Kirsch, M; Klimkovich, T; Kreuzer, P; Lanske, D; Merschmeyer, M; Meyer, A; Philipps, B; Pieta, H; Reithler, H; Schmitz, S A; Sonnenschein, L; Sowa, M; Steggemann, J; Szczesny, H; Teyssier, D; Zeidler, C; Bontenackels, M; Davids, M; Duda, M; Flügge, G; Geenen, H; Giffels, M; Haj Ahmad, W; Hermanns, T; Heydhausen, D; Kalinin, S; Kress, T; Linn, A; Nowack, A; Perchalla, L; Poettgens, M; Pooth, O; Sauerland, P; Stahl, A; Tornier, D; 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Ryan, M J; Seez, C; Sharp, P; Sidiropoulos, G; Stettler, M; Stoye, M; Takahashi, M; Tapper, A; Timlin, C; Tourneur, S; Vazquez Acosta, M; Virdee, T; Wakefield, S; Wardrope, D; Whyntie, T; Wingham, M; Cole, J E; Goitom, I; Hobson, P R; Khan, A; Kyberd, P; Leslie, D; Munro, C; Reid, I D; Siamitros, C; Taylor, R; Teodorescu, L; Yaselli, I; Bose, T; Carleton, M; Hazen, E; Heering, A H; Heister, A; John, J St; Lawson, P; Lazic, D; Osborne, D; Rohlf, J; Sulak, L; Wu, S; Andrea, J; Avetisyan, A; Bhattacharya, S; Chou, J P; Cutts, D; Esen, S; Kukartsev, G; Landsberg, G; Narain, M; Nguyen, D; Speer, T; Tsang, K V; Breedon, R; Calderon De La Barca Sanchez, M; Case, M; Cebra, D; Chertok, M; Conway, J; Cox, P T; Dolen, J; Erbacher, R; Friis, E; Ko, W; Kopecky, A; Lander, R; Lister, A; Liu, H; Maruyama, S; Miceli, T; Nikolic, M; Pellett, D; Robles, J; Searle, M; Smith, J; Squires, M; Stilley, J; Tripathi, M; Vasquez Sierra, R; Veelken, C; Andreev, V; Arisaka, K; Cline, D; Cousins, R; Erhan, S; Hauser, J; Ignatenko, M; Jarvis, C; Mumford, J; Plager, C; Rakness, G; Schlein, P; Tucker, J; Valuev, V; Wallny, R; Yang, X; Babb, J; Bose, M; Chandra, A; Clare, R; Ellison, J A; Gary, J W; Hanson, G; Jeng, G Y; Kao, S C; Liu, F; Liu, H; Luthra, A; Nguyen, H; Pasztor, G; Satpathy, A; Shen, B C; Stringer, R; Sturdy, J; Sytnik, V; Wilken, R; Wimpenny, S; Branson, J G; Dusinberre, E; Evans, D; Golf, F; Kelley, R; Lebourgeois, M; Letts, J; Lipeles, E; Mangano, B; Muelmenstaedt, J; Norman, M; Padhi, S; Petrucci, A; Pi, H; Pieri, M; Ranieri, R; Sani, M; Sharma, V; Simon, S; Würthwein, F; Yagil, A; Campagnari, C; D'Alfonso, M; Danielson, T; Garberson, J; Incandela, J; Justus, C; Kalavase, P; Koay, S A; Kovalskyi, D; Krutelyov, V; Lamb, J; Lowette, S; Pavlunin, V; Rebassoo, F; Ribnik, J; Richman, J; Rossin, R; Stuart, D; To, W; Vlimant, J R; Witherell, M; Apresyan, A; Bornheim, A; Bunn, J; Chiorboli, M; Gataullin, M; Kcira, D; Litvine, V; Ma, Y; Newman, H B; Rogan, C; Timciuc, V; Veverka, J; Wilkinson, R; Yang, Y; Zhang, L; Zhu, K; Zhu, R Y; Akgun, B; Carroll, R; Ferguson, T; Jang, D W; Jun, S Y; Paulini, M; Russ, J; Terentyev, N; Vogel, H; Vorobiev, I; Cumalat, J P; Dinardo, M E; Drell, B R; Ford, W T; Heyburn, B; Luiggi Lopez, E; Nauenberg, U; Stenson, K; Ulmer, K; Wagner, S R; Zang, S L; Agostino, L; Alexander, J; Blekman, F; Cassel, D; Chatterjee, A; Das, S; Gibbons, L K; Heltsley, B; Hopkins, W; Khukhunaishvili, A; Kreis, B; Kuznetsov, V; Patterson, J R; Puigh, D; Ryd, A; Shi, X; Stroiney, S; Sun, W; Teo, W D; Thom, J; Vaughan, J; Weng, Y; Wittich, P; Beetz, C P; Cirino, G; Sanzeni, C; Winn, D; Abdullin, S; Afaq, M A; Albrow, M; Ananthan, B; Apollinari, G; Atac, M; Badgett, W; Bagby, L; Bakken, J A; Baldin, B; Banerjee, S; Banicz, K; Bauerdick, L A T; Beretvas, A; Berryhill, J; Bhat, P C; Biery, K; Binkley, M; Bloch, I; Borcherding, F; Brett, A M; Burkett, K; Butler, J N; Chetluru, V; Cheung, H W K; Chlebana, F; Churin, I; Cihangir, S; Crawford, M; Dagenhart, W; Demarteau, M; Derylo, G; Dykstra, D; Eartly, D P; Elias, J E; Elvira, V D; Evans, D; Feng, L; Fischler, M; Fisk, I; Foulkes, S; Freeman, J; Gartung, P; Gottschalk, E; Grassi, T; Green, D; Guo, Y; Gutsche, O; Hahn, A; Hanlon, J; Harris, R M; Holzman, B; Howell, J; Hufnagel, D; James, E; Jensen, H; Johnson, M; Jones, C D; Joshi, U; Juska, E; Kaiser, J; Klima, B; Kossiakov, S; Kousouris, K; Kwan, S; Lei, C M; Limon, P; Lopez Perez, J A; Los, S; Lueking, L; Lukhanin, G; Lusin, S; Lykken, J; Maeshima, K; Marraffino, J M; Mason, D; McBride, P; Miao, T; Mishra, K; Moccia, S; Mommsen, R; Mrenna, S; Muhammad, A S; Newman-Holmes, C; Noeding, C; O'Dell, V; Prokofyev, O; Rivera, R; Rivetta, C H; Ronzhin, A; Rossman, P; Ryu, S; Sekhri, V; Sexton-Kennedy, E; Sfiligoi, I; Sharma, S; Shaw, T M; Shpakov, D; Skup, E; Smith, R P; Soha, A; Spalding, W J; Spiegel, L; Suzuki, I; Tan, P; Tanenbaum, W; Tkaczyk, S; Trentadue, R; Uplegger, L; Vaandering, E W; Vidal, R; Whitmore, J; Wicklund, E; Wu, W; Yarba, J; Yumiceva, F; Yun, J C; Acosta, D; Avery, P; Barashko, V; Bourilkov, D; Chen, M; Di Giovanni, G P; Dobur, D; Drozdetskiy, A; Field, R D; Fu, Y; Furic, I K; Gartner, J; Holmes, D; Kim, B; Klimenko, S; Konigsberg, J; Korytov, A; Kotov, K; Kropivnitskaya, A; Kypreos, T; Madorsky, A; Matchev, K; Mitselmakher, G; Pakhotin, Y; Piedra Gomez, J; Prescott, C; Rapsevicius, V; Remington, R; Schmitt, M; Scurlock, B; Wang, D; Yelton, J; Ceron, C; Gaultney, V; Kramer, L; Lebolo, L M; Linn, S; Markowitz, P; Martinez, G; Rodriguez, J L; Adams, T; Askew, A; Baer, H; Bertoldi, M; Chen, J; Dharmaratna, W G D; Gleyzer, S V; Haas, J; Hagopian, S; Hagopian, V; Jenkins, M; Johnson, K F; Prettner, E; Prosper, H; Sekmen, S; Baarmand, M M; Guragain, S; Hohlmann, M; Kalakhety, H; Mermerkaya, H; Ralich, R; Vodopiyanov, I; Abelev, B; Adams, M R; Anghel, I M; Apanasevich, L; Bazterra, V E; Betts, R R; Callner, J; Castro, M A; Cavanaugh, R; Dragoiu, C; Garcia-Solis, E J; Gerber, C E; Hofman, D J; Khalatian, S; Mironov, C; Shabalina, E; Smoron, A; Varelas, N; Akgun, U; Albayrak, E A; Ayan, A S; Bilki, B; Briggs, R; Cankocak, K; Chung, K; Clarida, W; Debbins, P; Duru, F; Ingram, F D; Lae, C K; McCliment, E; Merlo, J P; Mestvirishvili, A; Miller, M J; Moeller, A; Nachtman, J; Newsom, C R; Norbeck, E; Olson, J; Onel, Y; Ozok, F; Parsons, J; Schmidt, I; Sen, S; Wetzel, J; Yetkin, T; Yi, K; Barnett, B A; Blumenfeld, B; Bonato, A; Chien, C Y; Fehling, D; Giurgiu, G; Gritsan, A V; Guo, Z J; Maksimovic, P; Rappoccio, S; Swartz, M; Tran, N V; Zhang, Y; Baringer, P; Bean, A; Grachov, O; Murray, M; Radicci, V; Sanders, S; Wood, J S; Zhukova, V; Bandurin, D; Bolton, T; Kaadze, K; Liu, A; Maravin, Y; Onoprienko, D; Svintradze, I; Wan, Z; Gronberg, J; Hollar, J; Lange, D; Wright, D; Baden, D; Bard, R; Boutemeur, M; Eno, S C; Ferencek, D; Hadley, N J; Kellogg, R G; Kirn, M; Kunori, S; Rossato, K; Rumerio, P; Santanastasio, F; Skuja, A; Temple, J; Tonjes, M B; Tonwar, S C; Toole, T; Twedt, E; Alver, B; Bauer, G; Bendavid, J; Busza, W; Butz, E; Cali, I A; Chan, M; D'Enterria, D; Everaerts, P; Gomez Ceballos, G; Hahn, K A; Harris, P; Jaditz, S; Kim, Y; Klute, M; Lee, Y J; Li, W; Loizides, C; Ma, T; Miller, M; Nahn, S; Paus, C; Roland, C; Roland, G; Rudolph, M; Stephans, G; Sumorok, K; Sung, K; Vaurynovich, S; Wenger, E A; Wyslouch, B; Xie, S; Yilmaz, Y; Yoon, A S; Bailleux, D; Cooper, S I; Cushman, P; Dahmes, B; De Benedetti, A; Dolgopolov, A; Dudero, P R; Egeland, R; Franzoni, G; Haupt, J; Inyakin, A; Klapoetke, K; Kubota, Y; Mans, J; Mirman, N; Petyt, D; Rekovic, V; Rusack, R; Schroeder, M; Singovsky, A; Zhang, J; Cremaldi, L M; Godang, R; Kroeger, R; Perera, L; Rahmat, R; Sanders, D A; Sonnek, P; Summers, D; Bloom, K; Bockelman, B; Bose, S; Butt, J; Claes, D R; Dominguez, A; Eads, M; Keller, J; Kelly, T; Kravchenko, I; Lazo-Flores, J; Lundstedt, C; Malbouisson, H; Malik, S; Snow, G R; Baur, U; Iashvili, I; Kharchilava, A; Kumar, A; Smith, K; Strang, M; Alverson, G; Barberis, E; Boeriu, O; Eulisse, G; Govi, G; McCauley, T; Musienko, Y; Muzaffar, S; Osborne, I; Paul, T; Reucroft, S; Swain, J; Taylor, L; Tuura, L; Anastassov, A; Gobbi, B; Kubik, A; Ofierzynski, R A; Pozdnyakov, A; Schmitt, M; Stoynev, S; Velasco, M; Won, S; Antonelli, L; Berry, D; Hildreth, M; Jessop, C; Karmgard, D J; Kolberg, T; Lannon, K; Lynch, S; Marinelli, N; Morse, D M; Ruchti, R; Slaunwhite, J; Warchol, J; Wayne, M; Bylsma, B; Durkin, L S; Gilmore, J; Gu, J; Killewald, P; Ling, T Y; Williams, G; Adam, N; Berry, E; Elmer, P; Garmash, A; Gerbaudo, D; Halyo, V; Hunt, A; Jones, J; Laird, E; Marlow, D; Medvedeva, T; Mooney, M; Olsen, J; Piroué, P; Stickland, D; Tully, C; Werner, J S; Wildish, T; Xie, Z; Zuranski, A; Acosta, J G; Bonnett Del Alamo, M; Huang, X T; Lopez, A; Mendez, H; Oliveros, S; Ramirez Vargas, J E; Santacruz, N; Zatzerklyany, A; Alagoz, E; Antillon, E; Barnes, V E; Bolla, G; Bortoletto, D; Everett, A; Garfinkel, A F; Gecse, Z; Gutay, L; Ippolito, N; Jones, M; Koybasi, O; Laasanen, A T; Leonardo, N; Liu, C; Maroussov, V; Merkel, P; Miller, D H; Neumeister, N; Sedov, A; Shipsey, I; Yoo, H D; Zheng, Y; Jindal, P; Parashar, N; Cuplov, V; Ecklund, K M; Geurts, F J M; Liu, J H; Maronde, D; Matveev, M; Padley, B P; Redjimi, R; Roberts, J; Sabbatini, L; Tumanov, A; Betchart, B; Bodek, A; Budd, H; Chung, Y S; de Barbaro, P; Demina, R; Flacher, H; Gotra, Y; Harel, A; Korjenevski, S; Miner, D C; Orbaker, D; Petrillo, G; Vishnevskiy, D; Zielinski, M; Bhatti, A; Demortier, L; Goulianos, K; Hatakeyama, K; Lungu, G; Mesropian, C; Yan, M; Atramentov, O; Bartz, E; Gershtein, Y; Halkiadakis, E; Hits, D; Lath, A; Rose, K; Schnetzer, S; Somalwar, S; Stone, R; Thomas, S; Watts, T L; Cerizza, G; Hollingsworth, M; Spanier, S; Yang, Z C; York, A; Asaadi, J; Aurisano, A; Eusebi, R; Golyash, A; Gurrola, A; Kamon, T; Nguyen, C N; Pivarski, J; Safonov, A; Sengupta, S; Toback, D; Weinberger, M; Akchurin, N; Berntzon, L; Gumus, K; Jeong, C; Kim, H; Lee, S W; Popescu, S; Roh, Y; Sill, A; Volobouev, I; Washington, E; Wigmans, R; Yazgan, E; Engh, D; Florez, C; Johns, W; Pathak, S; Sheldon, P; Andelin, D; Arenton, M W; Balazs, M; Boutle, S; Buehler, M; Conetti, S; Cox, B; Hirosky, R; Ledovskoy, A; Neu, C; Phillips II, D; Ronquest, M; Yohay, R; Gollapinni, S; Gunthoti, K; Harr, R; Karchin, P E; Mattson, M; Sakharov, A; Anderson, M; Bachtis, M; Bellinger, J N; Carlsmith, D; Crotty, I; Dasu, S; Dutta, S; Efron, J; Feyzi, F; Flood, K; Gray, L; Grogg, K S; Grothe, M; Hall-Wilton, R; Jaworski, M; Klabbers, P; Klukas, J; Lanaro, A; Lazaridis, C; Leonard, J; Loveless, R; Magrans de Abril, M; Mohapatra, A; Ott, G; Polese, G; Reeder, D; Savin, A; Smith, W H; Sourkov, A; Swanson, J; Weinberg, M; Wenman, D; Wensveen, M; White, A

    2010-01-01

    In October and November 2008, the CMS collaboration conducted a programme of cosmic ray data taking, which has recorded about 270 million events. The Resistive Plate Chamber system, which is part of the CMS muon detection system, was successfully operated in the full barrel. More than 98% of the channels were operational during the exercise with typical detection efficiency of 90%. In this paper, the performance of the detector during these dedicated runs is reported.

  9. Operation of the multigap resistive plate chamber using a gas mixture free of flammable components

    CERN Document Server

    Akindinov, A; Antonioli, P; Arcelli, S; Basile, M; Cara Romeo, G; Cifarelli, Luisa; Cindolo, F; De Caro, A; De Pasquale, S; Di Bartolomeo, A; Fusco-Girard, M; Golovine, V; Guida, M; Hatzifotiadou, D; Kaidalov, A B; Kim, D H; Kim, D W; Kisselev, S M; Laurenti, G; Lee, K; Lee, S C; Lioublev, E; Luvisetto, M L; Margotti, A; Martemyanov, A N; Nania, R; Noferini, F; Otiougova, P; Pesci, A; Pinazza, O; Polozov, P A; Scapparone, E; Scioli, G; Sellitto, S B; Semeria, F; Smirnitsky, A V; Tchoumakov, M M; Usenko, E; Valenti, G; Voloshin, K G; Williams, M C S; Zagreev, B V; Zampolli, C; Zichichi, A

    2004-01-01

    We have investigated the operation of the multigap resistive plate chamber (MRPC) for the ALICE-TOF system with a gas mixture free of flammable components. Two different gas mixtures, with and without iso-C//4H//1//0 have been used to measure the performance of the MRPC. The efficiency, time resolution, total charge, and the fast to total charge ratio have been found to be comparable.

  10. Radiation-hard ceramic Resistive Plate Chambers for forward TOF and T0 systems

    Energy Technology Data Exchange (ETDEWEB)

    Akindinov, A., E-mail: Alexander.Akindinov@cern.ch [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Dreyer, J.; Fan, X.; Kämpfer, B. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Kiselev, S. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Kotte, R.; Garcia, A. Laso [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Malkevich, D. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Naumann, L. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Nedosekin, A.; Plotnikov, V. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Stach, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Sultanov, R.; Voloshin, K. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation)

    2017-02-11

    Resistive Plate Chambers with ceramic electrodes are the main candidates for a use in precise multi-channel timing systems operating in high-radiation conditions. We report the latest R&D results on these detectors aimed to meet the requirements of the forward T0 counter at the CBM experiment. RPC design, gas mixture, limits on the bulk resistivity of ceramic electrodes, efficiency, time resolution, counting rate capabilities and ageing test results are presented.

  11. Efficiency determination of resistive plate chambers for fast quasi-monoenergetic neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Roeder, M.; Cowan, T.E.; Kempe, M.; Yakorev, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universitaet Dresden, Dresden (Germany); Elekes, Z. [MTA ATOMKI, Debrecen (Hungary); Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Aumann, T.; Caesar, C. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Technische Universitaet Darmstadt, Darmstadt (Germany); Bemmerer, D.; Sobiella, M.; Stach, D.; Wagner, A. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Boretzky, K.; Hehner, J.; Heil, M. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Maroussov, V. [Universitaet zu Koeln, Koeln (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Nusair, O. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Al-Balqa Applied University, Salt (Jordan); Prokofiev, A.V. [Uppsala University, The Svedberg Laboratory, Uppsala (Sweden); Reifarth, R. [Johann Wolfgang Goethe - Universitaet, Frankfurt am Main (Germany); Zilges, A. [Universitaet zu Koeln, Koeln (Germany); Zuber, K. [Technische Universitaet Dresden, Dresden (Germany); Collaboration: R3B Collaboration

    2014-07-15

    Composite detectors made of stainless-steel converters and multigap resistive plate chambers have been irradiated with quasi-monoenergetic neutrons with a peak energy of 175 MeV. The neutron detection efficiency has been determined using two different methods. The data are in agreement with the output of Monte Carlo simulations. The simulations are then extended to study the response of a hypothetical array made of these detectors to energetic neutrons from a radioactive ion beam experiment. (orig.)

  12. Application of PSpice circuit simulator in development of resistive plate chamber detector

    International Nuclear Information System (INIS)

    Wang Yaping; Cai Xu

    2008-01-01

    An electrical model was presented for resistive plate chamber (RPC) detector. The readout signals of RPC detector were studied with PSpice simulation based on the model. The simulation results show a good agreement with real data and authoritative data. Physical performance of RPC detector can be predicted by the PSpice simulation, so this is an efficient means to optimize RPC detector's research and development. (authors)

  13. Characterization of reticulated vitreous carbon foam using a frisch-grid parallel-plate ionization chamber

    Science.gov (United States)

    Edwards, Nathaniel S.; Conley, Jerrod C.; Reichenberger, Michael A.; Nelson, Kyle A.; Tiner, Christopher N.; Hinson, Niklas J.; Ugorowski, Philip B.; Fronk, Ryan G.; McGregor, Douglas S.

    2018-06-01

    The propagation of electrons through several linear pore densities of reticulated vitreous carbon (RVC) foam was studied using a Frisch-grid parallel-plate ionization chamber pressurized to 1 psig of P-10 proportional gas. The operating voltages of the electrodes contained within the Frisch-grid parallel-plate ionization chamber were defined by measuring counting curves using a collimated 241Am alpha-particle source with and without a Frisch grid. RVC foam samples with linear pore densities of 5, 10, 20, 30, 45, 80, and 100 pores per linear inch were separately positioned between the cathode and anode. Pulse-height spectra and count rates from a collimated 241Am alpha-particle source positioned between the cathode and each RVC foam sample were measured and compared to a measurement without an RVC foam sample. The Frisch grid was positioned in between the RVC foam sample and the anode. The measured pulse-height spectra were indiscernible from background and resulted in negligible net count rates for all RVC foam samples. The Frisch grid parallel-plate ionization chamber measurement results indicate that electrons do not traverse the bulk of RVC foam and consequently do not produce a pulse.

  14. Development of a parallel plate ion chamber for radiation protection level

    International Nuclear Information System (INIS)

    Bottaro, Marcio; Landi, Mauricio; Moralles, Mauricio

    2011-01-01

    A new parallel plate vented ion chamber is proposed in this paper. The application of this chamber was primarily intended to the measurement of stray radiation in interventional procedures, but the energy response of about 2.6%, which was obtained in the first prototype, on the range from 40 to 150 kV using ISO 4037-1 narrow qualities, provided the possibility of a wide modality application on radiation protection. Primary studies with Maxwell 2D electromagnetic field simulator revealed an optimized model regarding effective volume and saturation voltage levels, which conferred to the ion chamber a dual entrance window feature. The development of this ion chamber has the main contribution of Monte Carlo calculations as a support tool to the establishment of the effective volume of the chamber and determination of the best materials for housing mounting and conductive elements, such as guard rings, electrode, and windows. Even the composition of the conductive layers, which would be neglected due to their very small thicknesses (about 35 μm), had important influence on the results and could be better understood with Monte Carlo N-Particle Transport Code System (MCNP) simulations. (author)

  15. Highly conductive composites for fuel cell flow field plates and bipolar plates

    Science.gov (United States)

    Jang, Bor Z; Zhamu, Aruna; Song, Lulu

    2014-10-21

    This invention provides a fuel cell flow field plate or bipolar plate having flow channels on faces of the plate, comprising an electrically conductive polymer composite. The composite is composed of (A) at least 50% by weight of a conductive filler, comprising at least 5% by weight reinforcement fibers, expanded graphite platelets, graphitic nano-fibers, and/or carbon nano-tubes; (B) polymer matrix material at 1 to 49.9% by weight; and (C) a polymer binder at 0.1 to 10% by weight; wherein the sum of the conductive filler weight %, polymer matrix weight % and polymer binder weight % equals 100% and the bulk electrical conductivity of the flow field or bipolar plate is at least 100 S/cm. The invention also provides a continuous process for cost-effective mass production of the conductive composite-based flow field or bipolar plate.

  16. Performance and simulation of a double-gap resistive plate chamber in the avalanche mode

    CERN Document Server

    Ahn Sung Hwan; Hong Byung Sik; Hong Seong Jong; Ito, M; Kang, T I; Kim, B I; Kim, J H; Kim, Y J; Kim, Y U; Koo, D G; Lee Hyup Woo; Lee, K B; Lee Kyong Sei; Lee Seok Jae; Lim, J K; Moon, D H; Nam, S K; Park, S; Park, W J; Rhee June Tak; Ryu, M S; Sim Kwang Souk

    2004-01-01

    We present a detailed analysis of the time and the charge signals of a prototype double-gap resistive plate chamber for the endcap region of the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC). The chamber was built with relatively low-resistivity bakelite. The time and the charge results demonstrate that the high- voltage plateau, which satisfies various CMS requirements for the efficiency, the noise cluster rate, the fraction of the large signal, and the streamer probability, can be extended at least up to 400 V with the present design. In addition, a simple avalanche multiplication model is studied in detail. The model can reproduce the experimental charge spectra reasonably well. The charge information enables us to estimate the effective Townsend coefficient in avalanche-mode operation.

  17. Effect of the linseed oil surface treatment on the performance of resistive plate chambers

    International Nuclear Information System (INIS)

    Abbrescia, M.; Colaleo, A.; Iaselli, G.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Ranieri, A.; Romano, F.; Arena, V.; Bonomi, G.; Braj, A.; Gianini, G.; Liguori, G.; Ratti, S.P.; Riccardi, C.; Viola, L.; Vitulo, P.

    1997-01-01

    Results on the behaviour of several bakelite resistive plate chambers (RPCs) without the linseed oil treatment of the internal electrodes will be presented. Efficiency, collected charge and cluster size distributions will be compared to the ones of a standard oiled RPC. Currents and single rate are the quantities most affected by the surface treatment of the electrodes beyond the optical/mechanical properties. A factor 4 less in currents and at least a factor 10 less in single rate is achieved using standard oiled RPCs operated in streamer mode. (orig.)

  18. Aging study for resistive plate chambers of the CMS muon trigger detector

    CERN Document Server

    Abbrescia, M; Iaselli, G; Loddo, F; Maggi, M; Marangelli, B; Natali, S; Nuzzo, S; Pugliese, G; Ranieri, A; Romano, F; Altieri, S; Belli, G; Bruno, G; Guida, R; Ratti, S P; Riccardi, C; Torre, P; Vitulo, P

    2003-01-01

    A long-term aging test of a Resistive Plate Chamber (RPC) was carried out with an intense gamma **1**3**7Cs source. The detector was operated in avalanche mode and had the bakelite surface treated with linseed oil. After the irradiation the estimated dose, charge and fluence were approximately equal to the expected values after 10 years of operation in the CMS barrel region. During and after the irradiation, the RPC performance was monitored with cosmic muons and showed no relevant aging effects. Moreover, no variation of the bakelite resistance was observed.

  19. The EEE Project: Cosmic rays, multigap resistive plate chambers and high school students

    CERN Document Server

    Abbrescia, M.; Antolini, R; Avanzini, C; Baldini Ferroli, R; Bencivenni, G; Bossini, E; Bressan, E; Chiavassa, A; Cicalo, C; Cifarelli, L; Coccia, E; De Gruttula, D; De Pasquale, S; Di Giovanni, A; D'Incecco, M; Doroud, K; Dreucci, M; Fabbri, FL; Frolov, V; Garbini, M; Gemme, G; Gnesi, I; Gustavino, C; Hatzifotiadu, D; La Rocca, P; Li, S; Moro, R; Miozzi, S; Massai, M; Maggiora, A; Librizzi, F; Piragino, G; Pilo, F; Perasso, L; Paoletti, R; Righini, GC; Scapparone, E; Sartorelli, G; Romano, F; Serci, S; Selvi, M; Scribano, A; Riggi, F; Regano, A; Squarcia, S; Spandre, G; Toselli, F; Taiuti, M; Zichichi, A; Zouyevski, R; Williams, MCS; Votano, L; Siddi, E; Panareo, M

    2012-01-01

    The Gas Gain Monitoring (GGM) system of the Resistive Plate Chamber (RPC) muon detector in the Compact Muon Solenoid (CMS) experiment provides fast and accurate determination of the stability in the working point conditions due to gas mixture changes in the closed loop recirculation system. In 2011 the GGM began to operate using a feedback algorithm to control the applied voltage, in order to keep the GGM response insensitive to environmental temperature and atmospheric pressure variations. Recent results are presented on the feedback method used and on alternative algorithms.

  20. Aging study for resistive plate chambers of the CMS muon trigger detector

    Energy Technology Data Exchange (ETDEWEB)

    Abbrescia, M.; Colaleo, A.; Iaselli, G.; Loddo, F.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Pugliese, G. E-mail: gabriella.pugliese@ba.infn.it; Ranieri, A.; Romano, F.; Altieri, S.; Belli, G.; Bruno, G.; Guida, R.; Ratti, S.P.; Riccardi, C.; Torre, P.; Vitulo, P

    2003-12-01

    A long-term aging test of a Resistive Plate Chamber (RPC) was carried out with an intense gamma {sup 137}Cs source. The detector was operated in avalanche mode and had the bakelite surface treated with linseed oil. After the irradiation the estimated dose, charge and fluence were approximately equal to the expected values after 10 years of operation in the CMS barrel region. During and after the irradiation, the RPC performance was monitored with cosmic muons and showed no relevant aging effects. Moreover, no variation of the bakelite resistance was observed.

  1. Performance of Resistive Plate Chambers for the muon detection at CMS

    Energy Technology Data Exchange (ETDEWEB)

    Abbrescia, M.; Colaleo, A.; Iaselli, G., E-mail: Giuseppe.Iaselli@ba.infn.it; Loddo, F.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Pugliese, G.; Ranieri, A.; Romano, F.; Altieri, S.; Bruno, G.; Gianini, G.; Ratti, S. P.; Viola, L.; Vitulo, P

    1999-08-01

    The latest results, still preliminary, of tests dedicated to study the performance of Resistive Plate Chamber for the CMS experiment are presented. Full efficiency with a 2 ns time resolution in conditions of incident flux up to 2 kHz/cm{sup 2} has been obtained. Detector uniformity has been studied and found to be well within the constraints due to the large surfaces used in the experiment. An aging test is currently being carried out and shows no significant performance variation with time.

  2. Response of multi-strip multi-gap resistive plate chamber using pulsed electron beam

    International Nuclear Information System (INIS)

    Datta Pramanik, U.; Chakraborty, S.; Rahaman, A.; Ray, J.; Chatterjee, S.; Bemmerer, D.; Elekes, Z.; Kempe, M.; Sobiella, M.; Stach, D.; Wagner, A.; Yakorev, D.; Leifels, Y.; Simon, H.

    2011-01-01

    A prototype of Multi-strip Multi-gap Resistive Plate Chamber (MMRPC) with active area 40 cm x 20 cm has been developed at SINP, Kolkata. Electron response of the developed detector was studied using the electron linac ELBE at Forschungszentrum Dresden-Rossendorf. The development of this detector started with the aim of developing a neutron detector but this ultrafast timing detector can be used efficiently for the purpose of medical imaging, security purpose and detection of minimum ionising particle. In this article detailed analysis of electron response to our developed MMRPC will be presented

  3. Single-electron pulse-height spectra in thin-gap parallel-plate chambers

    CERN Document Server

    Fonte, Paulo J R; Peskov, Vladimir; Policarpo, Armando

    1999-01-01

    Single-electron pulse-height spectra were measured in 0.6 and 1.2 mm parallel-plate chambers developed for the TOF system of the ALICE /LHC-HI experiment. Mixtures of Ar with ethane, isobutane, and SF/sub 6/ were studied. The observed spectrum shows a clear peak for all gases, suggesting efficient single-electron detection in thin parallel-plate structures. The pulse-height spectrum can be described by the weighted sum of an exponential and a Polya distribution, the Polya contribution becoming more important at higher gains. Additionally, it was found that the maximum gain, above 10/sup 6/, is limited by the appearance of streamers and depends weakly on the gas composition. The suitability of each mixture for single-electron detection is also quantitatively assessed. (8 refs).

  4. Flow-induced plastic collapse of stacked fuel plates

    Energy Technology Data Exchange (ETDEWEB)

    Davis, D C; Scarton, H A

    1985-03-01

    Flow-induced plastic collapse of stacked fuel plate assemblies was first noted in experimental reactors such as the ORNL High Flux Reactor Assembly and the Engineering Test Reactor (ETR). The ETR assembly is a stack of 19 thin flat rectangular fuel plates separated by narrow channels through which a coolant flows to remove the heat generated by fission of the fuel within the plates. The uranium alloyed plates have been noted to buckle laterally and plastically collapse at the system design coolant flow rate of 10.7 m/s, thus restricting the coolant flow through adjacent channels. A methodology and criterion are developed for predicting the plastic collapse of ETR fuel plates. The criterion is compared to some experimental results and the Miller critical velocity theory.

  5. Characteristics Air Flow in Room Chamber Test Refrigerator Household Energy Consumption with Inlet Flow Variation

    Science.gov (United States)

    Susanto, Edy; Idrus Alhamid, M.; Nasruddin; Budihardjo

    2018-03-01

    Room Chamber is the most important in making a good Testing Laboratory. In this study, the 2-D modeling conducted to assess the effect placed the inlet on designing a test chamber room energy consumption of household refrigerators. Where the geometry room chamber is rectangular and approaching the enclosure conditions. Inlet varied over the side parallel to the outlet and compared to the inlet where the bottom is made. The purpose of this study was to determine and define the characteristics of the airflow in the room chamber using CFD simulation. CFD method is used to obtain flow characteristics in detail, in the form of vector flow velocity and temperature distribution inside the chamber room. The result found that the position of the inlet parallel to the outlet causes air flow cannot move freely to the side of the floor, even flow of air moves up toward the outlet. While by making the inlet is below, the air can move freely from the bottom up to the side of the chamber room wall as well as to help uniform flow.

  6. Instability of a cantilevered flexible plate in viscous channel flow

    Science.gov (United States)

    Balint, T. S.; Lucey, A. D.

    2005-10-01

    The stability of a flexible cantilevered plate in viscous channel flow is studied as a representation of the dynamics of the human upper airway. The focus is on instability mechanisms of the soft palate (flexible plate) that cause airway blockage during sleep. We solve the Navier Stokes equations for flow with Reynolds numbers up to 1500 fully coupled with the dynamics of the plate motion solved using finite-differences. The study is 2-D and based upon linearized plate mechanics. When both upper and lower airways are open, the plate is found to lose its stability through a flutter mechanism and a critical Reynolds number exists. When one airway is closed, the plate principally loses its stability through a divergence mechanism and a critical flow speed exists. However, below the divergence-onset flow speed, flutter can exist for low levels of structural damping in the flexible plate. Our results serve to extend understanding of flow-induced instability of cantilevered flexible plates and will ultimately improve the diagnosis and treatment of upper-airway disorders.

  7. α spectrometer of parallel plate grid ionization chamber of high energy resolution

    International Nuclear Information System (INIS)

    Tong Boting; Wang Jianqing; Dong Mingli; Tang Peijia; Wang Xiaorong; Lin Cansheng

    2000-01-01

    Parallel plate grid ionization chamber with cathode area of 300 cm 2 was developed and applied to detect minimum α-emitters. It consist of a vacuum system, a gas cycle system of the parallel plate grid ionization chamber, electronics (a high voltage supply, a pre-amplifier and a main amplifier) and a computer-multichannel analyzer. The energy resolution is 23 keV FWHM for the 244 Cm electrostatic precipitated source. The integral background is typically 10 counts/h between 4 and 6 MeV. The detector efficiency is 50%. The minimum detecting activity is 3 x 10 -4 Bq (3σ, 30 hours). This spectrometer is suitable for detecting various samples, such as samples of the soil, water, air, bion, food, structural material, geology, archaeology, α-emitters of after processing and measuring α activity of accounting for and control of nuclear material and monitoring the artificial radioactivity nuclides of environment samples around nuclear facilities. The spectrometer is equipped with apparatus for preparing large area α source by using vacuum deposition or ultrasonic pulverization. The operating program of preparing source is simple. The source thickness can be kept in 40-60 μm/cm 2

  8. CMS Resistive Plate Chambers performance at $\\sqrt{s}=$13 TeV

    CERN Document Server

    Cabrera Mora, Andres Leonardo

    2016-01-01

    During 2015, the Large Hadron Collider (LHC) at CERN has reached the record-breaking center-of-mass energy of 13 TeV for proton-proton collisions. The LHC restarted operations successfully after a two-year technical stop, known as Long Shutdown 1 (LS1), needed for servicing and consolidating the CERN accelerator complex. The Compact Muon Solenoid detector, a general-purpose detector at LHC, benefited from LS1 by performing crucial tasks necessary to operate the detector at higher energies. In particular, the Resistive Plate Chamber (RPC) system, one of the three muon detector technologies in CMS, was serviced, re-commissioned, and upgraded with 144 new chambers to enhance muon trigger efficiency. The CMS RPC system confers robustness and redundancy to the muon trigger. A total of 1056 double-gap chambers cover the pseudo-rapidity region $ \\lvert\\eta\\rvert \\leq$1.6. The CMS RPC collaboration has exploited early data samples at 13 TeV for detector performance studies. These data allowed for a first characte...

  9. An Irrotational Flow Field That Approximates Flat Plate Boundary Conditions

    OpenAIRE

    Ruffa, Anthony A.

    2004-01-01

    An irrotational solution is derived for the steady-state Navier-Stokes equations that approximately satisfies the boundary conditions for flow over a finite flat plate. The nature of the flow differs substantially from boundary layer flow, with severe numerical difficulties in some regions.

  10. Asymptotics and Numerics for Laminar Flow over Finite Flat Plate

    NARCIS (Netherlands)

    Dijkstra, D.; Kuerten, J.G.M.; Kaper, Hans G.; Garbey, Mare; Pieper, Gail W.

    1992-01-01

    A compilation of theoretical results from the literature on the finite flat-plate flow at zero incidence is presented. This includes the Blasius solution, the Triple Deck at the trailing edge, asymptotics in the wake, and properties near the edges of the plate. In addition, new formulas for skin

  11. Hall effects on MHD flow past an accelerated plate

    International Nuclear Information System (INIS)

    Soundalgekar, V.M.; Ravi, S.; Hiremath, S.B.

    1980-01-01

    An exact solution of the MHD flow of an incompressible, electrically conducting, viscous fluid past a uniformly accelerated plate is presented. The velocity profiles are shown graphically and the numerical values of axial and transverse components of skin friction are tabulated. At high values of the Hall parameter, ωtau, the velocity is found to be oscillatory near the plate. (author)

  12. Unsteady MHD free convective flow past a vertical porous plate ...

    African Journals Online (AJOL)

    user

    International Journal of Engineering, Science and Technology .... dimensional MHD boundary layer on the body with time varying temperature. ... flow of an electrically conducting fluid past an infinite vertical porous flat plate coinciding with.

  13. Multigap resistive plate chambers for EAS study in the EEE Project

    CERN Document Server

    An, S; Badalà, A; Zichichi, A

    2007-01-01

    The EEE (Extreme Energy Events) Project, conceived by its leader Antonino Zichichi, is an experiment to study very high-energetic air showers (EAS) through the detection of the shower's muon component using a network of tracking detectors, installed in Italian high schools. The single tracking telescope is composed of three large area () Multi-gap Resistive Plate Chambers (MRPCs). The data collected by the telescopes will be used for studies of air showers and also for the search of time correlations between sites which are far apart. The first telescope, recently installed in the Liceo B. Touschek in Grottaferrata (Rome), is successfully running, and other telescopes are going to be installed in a short time in other towns, opening up the way for the first search of long-distance coincidences over a total area of .

  14. Resistive plate chamber neutron and gamma sensitivity measurement with a {sup 252}Cf source

    Energy Technology Data Exchange (ETDEWEB)

    Abbrescia, M.; Altieri, S.; Baratti, V.; Barnaba, O.; Belli, G.; Bruno, G.; Colaleo, A.; DeVecchi, C.; Guida, R. E-mail: roberto.guida@pv.infn.it; Iaselli, G.; Imbres, E.; Loddo, F.; Maggi, M.; Marangelli, B.; Musitelli, G.; Nardo, R.; Natali, S.; Nuzzo, S.; Pugliese, G.; Ranieri, A.; Ratti, S.; Riccardi, C.; Romano, F.; Torre, P.; Vicini, A.; Vitulo, P.; Volpe, F

    2003-06-21

    A bakelite double gap Resistive Plate Chamber (RPC), operating in avalanche mode, has been exposed to the radiation emitted from a {sup 252}Cf source to measure its neutron and gamma sensitivity. One of the two gaps underwent the traditional electrodes surface coating with linseed oil. RPC signals were triggered by fission events detected using BaF{sub 2} scintillators. A Monte Carlo code, inside the GEANT 3.21 framework with MICAP interface, has been used to identify the gamma and neutron contributions to the total number of collected RPC signals. A neutron sensitivity of (0.63{+-}0.02)x10{sup -3} (average energy 2 MeV) and a gamma sensitivity of (14.0{+-}0.5)x10{sup -3} (average energy 1.5 MeV) have been measured in double gap mode. Measurements done in single gap mode have shown that both neutron and gamma sensitivity are independent of the oiling treatment.

  15. Web-based monitoring tools for Resistive Plate Chambers in the CMS experiment at CERN

    International Nuclear Information System (INIS)

    Kim, M.S.; Ban, Y.; Cai, J.; Li, Q.; Liu, S.; Qian, S.; Wang, D.; Xu, Z.; Zhang, F.; Choi, Y.; Kim, D.; Goh, J.; Choi, S.; Hong, B.; Kang, J.W.; Kang, M.; Kwon, J.H.; Lee, K.S.; Lee, S.K.; Park, S.K.

    2014-01-01

    The Resistive Plate Chambers (RPC) are used in the CMS experiment at the trigger level and also in the standard offline muon reconstruction. In order to guarantee the quality of the data collected and to monitor online the detector performance, a set of tools has been developed in CMS which is heavily used in the RPC system. The Web-based monitoring (WBM) is a set of java servlets that allows users to check the performance of the hardware during data taking, providing distributions and history plots of all the parameters. The functionalities of the RPC WBM monitoring tools are presented along with studies of the detector performance as a function of growing luminosity and environmental conditions that are tracked over time

  16. Electron beam test of an iron/gas calorimeter based on ceramic parallel plate chambers

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, Gy.L.; Bizzeti, A.; Choumilov, E.; Civinini, C; Dalla Santa, F.; D'Alessandro, R.; Ferrando, A.; Fouz, M.C.; Herve, A.; Iglesias, A.; Ivochkin, V.; Josa, M.I.; Maggi, F.; Malinin, A.; Meschini, M.; Pojidaev, V.; Radermacher, E.; Salicio, J.M.

    1995-01-01

    The baseline option for the very forward calorimetry in the CMS experiment is an iron/gas calorimeter based on parallel plate chambers. A small prototype module of such a calorimeter, has been tested using electrons of 5 to 100 GeV/c momentum with various high voltages and two gases: CO2 (100%) and CF4/CO2 (80/20), at atmospheric pressure. The collected charge has been measured as a function of the high voltage and of the electron energy. The energy resolution has also been measured. Comparisons have been made with Monte-Carlo predictions. Agreement between data an simulation allows to make and estimation of the expected performance of a full size calorimeter. (Author) 23 refs

  17. Electron beam test of an iron/gas calorimeter based on ceramic parallel plate chambers

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, G.L.; Bizzeti, A.; choumilov, E.; Civinini, C.; Dalla Santa, F.; D'Alessandro, R.; Ferrando, A.; Fouz, M.C.; Herve, A.; Iglesias, A.; Ivochkin, V.; Josa, M.I.; Maggi, F.; Malininin, A.; Meschini, M.; Pojidaev, V.; Radermacher, E.; Salicio, J.M.

    1995-12-01

    The baseline option for the very forward calorimetry in the CMS experiment is an iron/gas calorimeter based on parallel plate chambers. A small prototype module of such a calorimeter, has been tested using electrons of 5 to 100 GeV/c momentum with various high voltages and two gases: CO 2 (100%) and CF 4 /CO 2 (80/20), at atmospheric pressure. The collected charge has been measured as a function of the high voltage and of the electron energy. The energy resolution has also been measured. Comparisons have been made with Monte-Carlo predictions. Agreement between data an simulation allows to make and estimation of the expected performance of a full size calorimeter. (Author)

  18. A large-area glass-resistive plate chamber with multistrip readout

    CERN Document Server

    Petrovici, M; Hildenbrand, K D; Augustinski, G; Ciobanu, M; Cruceru, I; Duma, M; Hartmann, O; Koczón, P; Kress, T; Marquardt, M; Moisa, D; Petris, M; Schröder, C; Simion, V; Stoicea, G; Weinert, J

    2002-01-01

    A completely new configuration of a glass resistive-plate chamber (GRPC) was built and tested. It consists of a double two-gap structure of electrodes with an active area of about 400 cm sup 2 and is read out via a central multistrip printed circuit board. In measurements with a sup 6 sup 0 Co source and p, d particles of 1.5 A GeV time resolutions better than 80 ps, position resolution along the strips of 5-6 mm and efficiencies larger than 95% were obtained using available fast standard electronics. These results open the possibility of constructing compact TOF detectors of high resolution and high granularity.

  19. Response of resistive plate chamber to e+/e- at E < 100 MeV

    International Nuclear Information System (INIS)

    Rhee, J T; Jamil, M; Chun, Christopher; Yin, Bingzhu; Jeon, Y J

    2006-01-01

    Resistive plate chambers (RPCs) will be installed as one of the important tracking detectors both in the endcap and barrel area CMS muon stations. These stations will be exposed to high gamma, neutron and positron/electron background radiation environment during the LHC machine operation. For the safe operation of these detectors, it is necessary to monitor these kinds of radiation. A simulation test has been carried out with the RPC at e + /e - fluxes using the dose and fluence equivalent to LHC 10 years operation. The simulation studies of RPC to e + /e - of energy 0.1 < E < 100 MeV have been performed using the GEANT 3.21 and GEANT4 Monte Carlo packages. By employing these two packages, good agreement of the simulation results is attained

  20. An encoding readout method used for Multi-gap Resistive Plate Chambers (MRPCs) for muon tomography

    Science.gov (United States)

    Yue, X.; Zeng, M.; Wang, Y.; Wang, X.; Zeng, Z.; Zhao, Z.; Cheng, J.

    2014-09-01

    A muon tomography facility has been built in Tsinghua University. Because of the low flux of cosmic muon, an encoding readout method, based on the fine-fine configuration, was implemented for the 2880 channels induced signals from the Multi-gap Resistive Plate Chamber (MRPC) detectors. With the encoding method, the number of the readout electronics was dramatically reduced and thus the complexity and the cost of the facility was reduced, too. In this paper, the details of the encoding method, and the overall readout system setup in the muon tomography facility are described. With the commissioning of the facility, the readout method works well. The spatial resolution of all MRPC detectors are measured with cosmic muon and the preliminary imaging result are also given.

  1. An encoding readout method used for Multi-gap Resistive Plate Chambers (MRPCs) for muon tomography

    International Nuclear Information System (INIS)

    Yue, X; Zeng, M; Wang, Y; Wang, X; Zeng, Z; Zhao, Z; Cheng, J

    2014-01-01

    A muon tomography facility has been built in Tsinghua University. Because of the low flux of cosmic muon, an encoding readout method, based on the fine-fine configuration, was implemented for the 2880 channels induced signals from the Multi-gap Resistive Plate Chamber (MRPC) detectors. With the encoding method, the number of the readout electronics was dramatically reduced and thus the complexity and the cost of the facility was reduced, too. In this paper, the details of the encoding method, and the overall readout system setup in the muon tomography facility are described. With the commissioning of the facility, the readout method works well. The spatial resolution of all MRPC detectors are measured with cosmic muon and the preliminary imaging result are also given

  2. Performance, operation and detector studies with the ATLAS Resistive Plate Chambers

    International Nuclear Information System (INIS)

    Aielli, G; Bindi, M; Polini, A

    2013-01-01

    Resistive Plate Chambers provide the barrel region of the ATLAS detector with an independent muon trigger and a two-coordinate measurement. The chambers, arranged in three concentric double layers, are operated in a strong magnetic toroidal field and cover a surface area of about 4000 m 2 . During 2011 the LHC has provided proton-proton collisions at 7 TeV in the center-of-mass frame with a steady increase in instantaneous luminosity, summing up to about 5 fb −1 . The operational experience for this running period is presented along with studies of the detector performance as a function of luminosity, environmental conditions and working point settings. Non-event based information including in particular the large number of gas gap currents, individually monitored with nA accuracy, have been used to study the detector behavior with growing luminosity and beam currents. These data are shown to provide, when calibrated, an independent luminosity measurement and a crucial handle for understanding the ATLAS backgrounds well beyond the scope of muon triggering and detection. The measurements presented here allow to plan a strategy for the data taking in the next years and make some predictions about the detector performance at higher luminosities. They also improve the knowledge on RPC detector physics.

  3. Coupled oscillations of flow along a perforated plate

    International Nuclear Information System (INIS)

    Celik, E.; Rockwell, D.

    2004-01-01

    Turbulent shear flow past a perforated plate bounded by a closed cavity can give rise to highly coherent oscillations, which have a wavelength of the order of the plate length. The present investigation focuses on the coupling between unsteady events on either side of the plate when the oscillations are self-sustaining. A cinema technique of high-image-density particle image velocimetry, which provides a space-time representation of the unsteadiness at a large number of locations over entire planes, is employed to characterize the distinctively different patterns of flow structure on the back (low-speed) side of the plate relative to those on the front (high-speed) side. Global cross-spectral analysis leads to patterns of spectral peaks and phase variations, along and across the plate. This approach, along with complementary types of image evaluation, delineates the physics of the oscillations, which include downstream propagating disturbances along either side of the plate and a coherent region of unsteadiness at its trailing-edge. On the backside of the plate, a sequence of upstream-oriented, pulsatile jets are formed, and the time-averaged flow pattern is a counterflow wall jet

  4. γ-converting plate system for neutrino-deuterium exposures in the FNAL 15-foot bubble chamber

    International Nuclear Information System (INIS)

    Hanlon, J.; Mann, W.A.; Sommars, S.; Wald, H.

    1978-01-01

    During May 18-20 of this year the hydrogen-filled 15-foot bubble chamber at Fermilab was operated with an array of four half-inch thick stainless steel plates mounted in downstream portions of the fiducial volume. Notes from the test run, and results from a Monte Carlo study of efficiencies of the plate array for detection of photons and positrons in final states produced in a wide-band neutrino--deuterium exposure, are presented

  5. Energy dependence of an ionization chamber with parallel plates in standard gamma and x-radiation fields

    International Nuclear Information System (INIS)

    Batistella, M.A.; Caldas, L.V.E.

    1988-09-01

    The characteristics of low energy X-radiation standard fields were determined and the energy dependence of a ionization chamber of the superficial type, with parallel plates and fixed volume, normally utilized in the dosimetry at the Radiotherapy level was studied. The possibility of adaptation of this chamber type for use in gamma radiation dosimetry was verified. Different thickness Lucite build-up caps, from 2.0 up to 5.5 mm, were produced and tested in 60 Co and 137 Cs gamma radiation fields. This type of detector, with the adequate build-up cap, presented a performance comparable to that of the thimble type ionization chamber. It was concluded that it is not necessary to use different kinds of chambers for each high and mean energy interval. The superficial chamber, specially produced to detect low energy X-radiation, may be adapted to detect gamma radiation. (author) [pt

  6. Comparing contact and immersion freezing from continuous flow diffusion chambers

    Directory of Open Access Journals (Sweden)

    B. Nagare

    2016-07-01

    process that is enhanced compared to immersion freezing due to the position of the INP on the droplet, and we discriminate it from collisional contact freezing, which assumes an enhancement due to the collision of the particle with the droplet. For best comparison with contact freezing results, immersion freezing experiments of the same INPs were performed with the continuous flow diffusion chamber Immersion Mode Cooling chAmber–Zurich Ice Nucleation Chamber (IMCA–ZINC for a 3 s residence time. In IMCA–ZINC, each INP is activated into a droplet in IMCA and provides its surface for ice nucleation in the ZINC chamber. The comparison of contact and immersion freezing results did not confirm a general enhancement of freezing efficiency for contact compared with immersion freezing experiments. For AgI particles the onset of heterogeneous freezing in CLINCH was even shifted to lower temperatures compared with IMCA–ZINC. For ATD, freezing efficiencies for contact and immersion freezing experiments were similar. For kaolinite particles, contact freezing became detectable at higher temperatures than immersion freezing. Using contact angle information between water and the INP, it is discussed how the position of the INP in or on the droplets may influence its ice nucleation activity.

  7. Theoretical study of flow ripple for an aviation axial-piston pump with damping holes in the valve plate

    OpenAIRE

    Guan, Changbin; Jiao, Zongxia; He, Shouzhan

    2014-01-01

    Based on the structure of a certain type of aviation axial-piston pump’s valve plate which adopts a pre-pressurization fluid path (consisting a damping hole, a buffer chamber, and an orifice) to reduce flow ripple, a single-piston model of the aviation axial-piston pump is presented. This single-piston model comprehensively considers fluid compressibility, orifice restriction effect, fluid resistance in the capillary tube, and the leakage flow. Besides, the instantaneous discharge areas used ...

  8. Study of gas mixtures and ageing of the multigap resistive plate chamber used for the ALICE TOF

    CERN Document Server

    Akindinov, A; Anselmo, F; Antonioli, P; Basile, M; Cara Romeo, G; Cifarelli, Luisa; Cindolo, F; Cosenza, F; D'Antone, I; De Caro, A; De Pasquale, S; Di Bartolomeo, A; Fusco-Girard, M; Golovine, V; Guerzoni, M; Guida, M; Hatzifotiadou, D; Kaidalov, A B; Kim, D H; Kim, D W; Kisselev, S M; Laurenti, G; Lioublev, E; Lee, K; Lee, S C; Luvisetto, M L; Margotti, A; Martemyanov, A N; Massera, F; Meneghini, S; Michinelli, R; Nania, R; Otiougova, P; Pancaldi, G; Pesci, A; Pilastrini, R; Pinazza, O; Polozov, P A; Rizzi, M; Scapparone, E; Scioli, G; Sellitto, S B; Semeria, F; Serra, S; Smirnitsky, A V; Tchoumakov, M M; Ugolini, E; Usenko, E; Valenti, G; Voloshin, K G; Williams, M C S; Zagreev, B V; Zampolli, C; Zichichi, A; Zucchini, A; Zuffa, M

    2004-01-01

    We present in this paper a study of the ALICE-TOF Multigap Resistive Plate Chamber (MRPC) performance by using several gas mixtures. We also present a search for possible ageing effects, by studying two MRPCs irradiated at the CERN Gamma Irradiation Facility.

  9. The multigap resistive plate chamber as time-of-flight detector for the STAR experiment at RHIC

    International Nuclear Information System (INIS)

    Lamas V, J.

    2002-01-01

    The multigap resistive plate chamber (MRPC) is a suitable candidate for the time-of-flight system for the STAR experiment at RHIC at the BNL. A time resolution of 50 ps with an efficiency of 98% has been measured with MRPCs composed of 6 gas gaps of 220 μm. Results obtained during the year 2000 are reported here

  10. New terrestrial heat flow measurements on the Nazca Plate

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, R N [Columbia Univ., Palisades, NY; Langseth, M G; Vacquier, V; Francheteau, J

    1976-03-01

    Sixty-seven new heat flow measurements on the Nazca Plate are reported, and the thermal regimes of three specific areas on the plate are examined. The Nazca Ridge is an aseismic ridge which may have been generated as an ''island trail'' from the Easter Island ''hot spot'' and/or may be a fossil transform fault. The Nazca Ridge has lower heat flow than the surrounding sea floor implying that the ridge might have low ''effective'' thermal conductivity causing heat to preferentially flow or refract to surrounding ocean crust which has higher conductivity, or, the low heat flow values may be caused by hydrothermal circulation on the ridge. The Carnegie Plateau is an elevated region south of the Carnegie Ridge on the northeastern Nazca Plate with high heat flow and shallow topography consistent with an age of less than 20 m.y. B.P. The central Nazca Plate is an area of highly variable heat flow which is possibly related to thin sediment and to rough regional topography.

  11. Optimization Design of Bipolar Plate Flow Field in PEM Stack

    Science.gov (United States)

    Wen, Ming; He, Kanghao; Li, Peilong; Yang, Lei; Deng, Li; Jiang, Fei; Yao, Yong

    2017-12-01

    A new design of bipolar plate flow field in proton exchange membrane (PEM) stack was presented to develop a high-performance transfer efficiency of the two-phase flow. Two different flow fields were studied by using numerical simulations and the performance of the flow fields was presented. the hydrodynamic properties include pressure gap between inlet and outlet, the Reynold’s number of the two types were compared based on the Navier-Stokes equations. Computer aided optimization software was implemented in the design of experiments of the preferable flow field. The design of experiments (DOE) for the favorable concept was carried out to study the hydrodynamic properties when changing the design parameters of the bipolar plate.

  12. Hall effects on MHD flow past an accelerated plate

    Directory of Open Access Journals (Sweden)

    Deka R.K.

    2008-01-01

    Full Text Available The simultaneous effects of rotation and Hall current on the hydromagnetic flow past an accelerated horizontal plate relative to a rotating fluid is presented. It is found that for given values of m (Hall parameter, M (Hartmann number and an imposed rotation parameter Ω satisfying Ω = M 2m/(1 + m2, the transverse motion (transverse to the main flow disappears and the fluid moves in the direction of the plate only. The effects of the parameters m, M and Ω on the axial and transverse velocity profiles are shown graphically, whereas the effects of the parameters on the skin-friction components are shown by tabular values.

  13. Analysis and interpretation of the performance degradation of glass Resistive Plate Chambers operated in streamer mode

    CERN Document Server

    Calcaterra, A; Patteri, P; Piccolo, M; Della Mea, G; Restello, S; Ferri, F; Musella, P; Redaelli, N; Tabarelli de Fatis, T; Tinti, G; Mannocchi, G; Trinchero, G

    2007-01-01

    The long-term stability of Resistive Plate Chambers (RPCs) with glass electrodes was studied for one year with a dedicated test station hosting about 10 m2 of detectors. RPCs were operated in streamer mode with a ternary gas mixture containing argon (27%), isobutane (9%) and tetrafluoroethane (64%). Environmental conditions were kept under control and, in particular, the water pollution in the gas, deemed responsible for the degradation of glass RPC performance, was monitored never to exceed 30 ppm in the exhaust line. Evidence for a substantial aging of the detectors was observed, resulting in a loss of efficiency correlated to an increased rate of spurious streamers. This can be ascribed to the chemical attack of the glass surface by hydrofluoric acid formed in the streamer process, as confirmed by detailed morphological and chemical analyses of the electrode surface. Our results strengthen the indication that the instability of glass RPCs in the long term is related to the use of fluorocarbons as quenching...

  14. Signal coupling and signal integrity in multi-strip resistive plate chambers used for timing applications

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Diaz, Diego, E-mail: D.Gonzalez-Diaz@gsi.de [GSI Helmholtzcenter for Heavy Ion Research, Darmstadt (Germany); Technical University, Darmstadt (Germany); Department of Engineering Physics, Tsinghua University, Beijing (China); Chen Huangshan; Wang Yi [Technical University, Darmstadt (Germany)

    2011-08-21

    We have systematically studied the transmission of electrical signals along several 2-strip Resistive Plate Chambers (RPCs) in the frequency range f=0.1-3.5GHz. Such a range was chosen to fully cover the bandwidth associated to the very short rise-times of signals originated in RPCs used for sub-100 ps timing applications. This work conveys experimental evidence of the dominant role of modal dispersion in counters built at the 1 m scale, a fact that results in large cross-talk levels and strong signal shaping. It is shown that modal dispersion appears in RPCs due to their inherent unbalance between capacitive and inductive coupling. A practical way to restore this symmetry has been introduced (hereafter 'electrostatic compensation'), allowing for a cross-talk suppression factor up to x12 and a rise-time reduction by 200 ps. Under conditions of compensation the signal transmission is only limited by dielectric losses, yielding a length-dependent cutoff frequency of around 1 GHz for propagation along 2 m in typical float glass-based RPCs. It is further shown that 'electrostatic compensation' can be achieved for an arbitrary number of strips as long as the nature of the coupling is 'short-range', that is an almost exact assumption for typical strip-line RPCs. This work extends the bandwidth of previous studies by a factor ofx20.

  15. Testing of multigap Resistive Plate Chambers for Electron Ion Collider Detector Development

    Science.gov (United States)

    Hamilton, Hannah; Phenix Collaboration

    2015-10-01

    Despite decades of research on the subject, some details of the spin structure of the nucleon continues to be unknown. To improve our knowledge of the nucleon spin structure, the construction of a new collider is needed. This is one of the primary goals of the proposed Electron Ion Collider (EIC). Planned EIC spectrometers will require good particle identification. This can be provided by time of flight (TOF) detectors with excellent timing resolutions of 10 ps. A potential TOF detector that could meet this requirement is a glass multigap resistive plate chamber (mRPC). These mRPCs can provide excellent timing resolution at a low cost. The current glass mRPC prototypes have a total of twenty 0.1 mm thick gas gaps. In order to test the feasibility of this design, a cosmic test stand was assembled. This stand used the coincidence of scintillators as a trigger, and contains fast electronics. The construction, the method of testing, and the test results of the mRPCs will be presented.

  16. Development and Evaluation of the Muon Trigger Detector Using a Resistive Plate Chamber

    International Nuclear Information System (INIS)

    Park, Byeong Hyeon; Kim, Yong Kyun; Kang, Jeong Soo; Kim, Young Jin; Choi, Ihn Jea; Kim, Chong; Hong, Byung Sik

    2011-01-01

    The PHENIX Experiment is the largest of the four experiments that have taken data at the Relativistic Heavy Ion Collider. PHENIX, the Pioneering High Energy Nuclear Interaction eXperiment, is designed specifically to measure direct probes of the collisions such as electrons, muons, and photons. The primary goal of PHENIX is to discover and study a new state of matter called the Quark-Gluon Plasma. Among many particles, muons coming from W-boson decay gives us key information to analyze the spin of proton. Resistive plate chambers are proposed as a suitable solution as a muon trigger because of their fast response and good time resolution, flexibility in signal readout, robustness and the relatively low cost of production. The RPC detectors for upgrade were assembled and their performances were evaluated. The procedure to make the detectors better was optimized and described in detail in this thesis. The code based on ROOT was written and by using this the performance of the detectors made was evaluated, and all of the modules for north muon arm met the criteria and installation at PHENIX completed in November 2009. As RPC detectors that we made showed fast response, capacity of covering wide area with a resonable price and good spatial resolution, this will give the opportunity for applications, such as diagnosis and customs inspection system

  17. Development and evaluation of the muon trigger detector using a resistive plate chamber

    International Nuclear Information System (INIS)

    Park, Byeong Hyeon

    2010-08-01

    The PHENIX Experiment is the largest of the four experiments that have taken data at the Relativistic Heavy Ion Collider. PHENIX, the Pioneering High Energy Nuclear Interaction experiment, is an exploratory experiment for the investigation of high energy collisions of heavy ions and protons. PHENIX is designed specifically to measure direct probes of the collisions such as electrons, muons, and photons. The primary goal of PHENIX is to discover and study a new state of matter called the Quark-Gluon Plasma. Among many particles, muons coming from W-boson decay gives us key information to analyze the spin of proton. Resistive plate chambers are proposed as a suitable solution as a muon trigger because of their fast response and good time resolution, flexibility in signal readout, robustness and the relatively low cost of production. The RPC detectors for upgrade were assembled and their performances were evaluated. The procedure to make the detectors better was optimized and described in detail in this thesis. The code based on ROOT was written and by using this the performance of the detectors made was evaluated, and all of the modules for north muon arm met the criteria and installation at PHENIX completed in November 2009. As RPC detectors that we made showed fast response, capacity of covering wide area with a resonable price and good spatial resolution, this will give the opportunity for applications,such as diagnosis and customs inspection system

  18. Testing of a resistive plate chamber using NINO-ASIC based front end electronics

    International Nuclear Information System (INIS)

    Mondal, M.; Saini, J.; Ahammed, Z.; Chattopadhyay, S.; Ganai, R.; Barai, C.

    2017-01-01

    The Resistive Plate Chamber (RPC) has shown promising results while testing with the NINO FEE board. It has shown ∼ 80% efficiency in detecting cosmic muons with a noise rate of ∼ 40 Hz/cm 2 . The low threshold in the NINO board may be a possible reason for high noise rate. We plan to test the RPC for different gas mixtures to achieve an efficiency above 95%. The calibration of the NINO onboard threshold with input pulse amplitude need to be done. The time resolution of RPC is ∼ 2.66 ns at 12 kV for avalanche mode gas mixture. The minimum time resolution of the RPC has to determined by measuring the time spectra over the full plateau region of voltages. The signal charge has to be measured by time over- threshold for slewing correction. As J7 input of the board was not working properly, efficiency and noise rate data for the particular input has not been measured

  19. Timing measurements at ELBE on multigap resistive plate chamber prototypes for NeuLAND

    Energy Technology Data Exchange (ETDEWEB)

    Yakorev, Dmitry; Bemmerer, Daniel; Cowan, Tom; Stach, Daniel; Wagner, Andreas [Forschungszentrum Dresden-Rossendorf (FZD), Dresden (Germany); Aumann, Tom; Boretzky, Konstanze; Hehner, Joerg; Heil, Michael; Prokopowicz, Wawrczek; Reifarth, Rene; Schrieder, Gerhard [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany); Elvers, Michael; Zilges, Andreas [Universitaet Koeln (Germany); Kratz, Jens Volker; Rossi, Dominic [Johannes-Gutenberg-Universitaet, Mainz (Germany)

    2009-07-01

    The NeuLAND detector for fast neutrons (0.2-1 GeV) at the R3B experiment at FAIR aims for high time and spatial resolutions ({sigma}{sub t}<100 ps, {sigma}{sub x,y,z}<1 cm). The detector will consist of about 60 sequences of a stacked structure from iron converter material and multigap resistive plate chambers (MRPC's). The secondary charged particles stemming from hadronic interactions of the high energetic neutrons in the converter will be detected in the MRPC's, with excellent timing properties. As part of the ongoing development of the NeuLAND detector, MRPC prototypes designed for this application have been studied at the superconducting electron linac ELBE in Dresden with its picosecond time structure. The ELBE experiments show that the prototypes studied so far have efficiency {>=}90% for minimum ionizing particles in a 2 x 2 gap structure and fulfill the called for time resolution.

  20. Observation of Cherenkov rings using a low-pressure parallel-plate chamber and a solid cesium-iodide photocathode

    International Nuclear Information System (INIS)

    Lockyer, N.S.; Millan, J.E.; Lu, C.; McDonald, K.T.; Lopez, A.

    1993-01-01

    We have observed Cherenkov rings from minimum-ionizing particles using a low-pressure, parallel-plate pad-chamber with a cesium-iodide solid photocathode. This detector is blind to minimum-ionizing particles, and sensitive to Cherenkov photons of wavelengths 170-210 nm. An average of 5 photoelectrons per Cherenkov ring were detected using a 2-cm-thick radiator of liquid C 6 F 14 . This paper reports on the chamber construction, photocathode preparation and testbeam results. (orig.)

  1. Performance test of the Multi-gap Resistive Plate Chamber (MRPC) with cosmic ray

    Science.gov (United States)

    Ikeda, Michihiko; Akieda, Tomomi; Tomita, Shoko; Ninomiya, Aki

    2014-09-01

    MRPC is a gaseous ionization detector, which a good timing resolution has been used practically in the nuclear and particle physics experiment. A mixed gas of SF6 and Fleon 134a was flowed through the gaps between high resistive plates (500 μm thickness glass). A high electric field of ~2 ×106 [V/m] was applied between the plates. A charged particle passes through the MRPC and causes avalanche amplification. We constructed a relatively small MRPC with a readout pad (20 mm × 50 mm). The development is motivated by feasibility study of the MRPC as a photon tagger at the Research Center for Electron Photon Science (ELPH), Tohoku University. The photon tagger needs a good timing resolution (<100 ps), therefore we studied the small size MRPC, while a large sized MRPCs are widely used in nuclear and particle experiments. The MRPC can operate under the strong magnetic field and thus it can be a good candidate as an electron detector placed in the magnet. We tested the HV dependence of time resolution of the MRPC with cosmic rays. The MRPC will be demonstrated at the open campus of the Tohoku University as an example of nuclear experimental detectors. We will measure the zenith angle and velocity distributions of cosmic ray.

  2. Role of mantle flow in Nubia-Somalia plate divergence

    Science.gov (United States)

    Stamps, D. S.; Iaffaldano, G.; Calais, E.

    2015-01-01

    Present-day continental extension along the East African Rift System (EARS) has often been attributed to diverging sublithospheric mantle flow associated with the African Superplume. This implies a degree of viscous coupling between mantle and lithosphere that remains poorly constrained. Recent advances in estimating present-day opening rates along the EARS from geodesy offer an opportunity to address this issue with geodynamic modeling of the mantle-lithosphere system. Here we use numerical models of the global mantle-plates coupled system to test the role of present-day mantle flow in Nubia-Somalia plate divergence across the EARS. The scenario yielding the best fit to geodetic observations is one where torques associated with gradients of gravitational potential energy stored in the African highlands are resisted by weak continental faults and mantle basal drag. These results suggest that shear tractions from diverging mantle flow play a minor role in present-day Nubia-Somalia divergence.

  3. Influence of Reduced Mass Flow Rate and Chamber Backpressure on Swirl Injector Fluid Mechanics

    Science.gov (United States)

    Kenny, R Jeremy; Hulka, James R.

    2008-01-01

    Industry interest in variable-thrust liquid rocket engines places a demand on engine injector technology to operate over a wide range of liquid mass flow rates and chamber backpressures. One injection technology of current interest for variable thrust applications is an injector design with swirled fluids. Current swirl injector design methodologies do not take into account how swirl injector design parameters respond to elevated chamber backpressures at less than design mass flow rates. The current work was created to improve state-of-the-art swirl injector design methods in this area. The specific objective was to study the effects of elevated chamber backpressure and off-design mass flow rates on swirl injector fluid mechanics. Using a backpressure chamber with optical access, water was flowed through a swirl injector at various combinations of chamber backpressure and mass flow rates. The film thickness profile down the swirl injector nozzle section was measured through a transparent nozzle section of the injector. High speed video showed measurable increases in the film thickness profile with application of chamber backpressure and mass flow rates less than design. At prescribed combinations of chamber backpressure and injected mass flow rate, a discrete change in the film thickness profile was observed. Measured injector discharge coefficient values showed different trends with increasing chamber backpressure at low mass flow rates as opposed to near-design mass flow rates. Downstream spray angles showed classic changes in morphology as the mass flow rate was decreased below the design value. Increasing chamber backpressure decreased the spray angle at any injection mass flow rate. Experimental measurements and discussion of these results are reported in this paper.

  4. Streamer free operation of a 2 mm gap resistive plate chamber with $C_{2}F_{5}H$

    CERN Document Server

    Cerron-Zeballos, E; Hatzifotiadou, D; Lamas-Valverde, J; Williams, M C S; Zichichi, A

    1999-01-01

    It is necessary to operate the resistive plate chamber (RPC) in avalanche mode to obtain high efficiency at elevated particle fluxes. We examine this mode of operation with a 2 mm gap RPC using gas mixtures containing C/sub 2/F/sub 4/H/sub 2/ and C/sub 2/F/sub 5/H. In order to explain the data we propose that the avalanche growth is strongly limited by space charge effects. (10 refs).

  5. Chaos control for the plates subjected to subsonic flow

    Science.gov (United States)

    Norouzi, Hamed; Younesian, Davood

    2016-07-01

    The suppression of chaotic motion in viscoelastic plates driven by external subsonic air flow is studied. Nonlinear oscillation of the plate is modeled by the von-Kármán plate theory. The fluid-solid interaction is taken into account. Galerkin's approach is employed to transform the partial differential equations of the system into the time domain. The corresponding homoclinic orbits of the unperturbed Hamiltonian system are obtained. In order to study the chaotic behavior of the plate, Melnikov's integral is analytically applied and the threshold of the excitation amplitude and frequency for the occurrence of chaos is presented. It is found that adding a parametric perturbation to the system in terms of an excitation with the same frequency of the external force can lead to eliminate chaos. Variations of the Lyapunov exponent and bifurcation diagrams are provided to analyze the chaotic and periodic responses. Two perturbation-based control strategies are proposed. In the first scenario, the amplitude of control forces reads a constant value that should be precisely determined. In the second strategy, this amplitude can be proportional to the deflection of the plate. The performance of each controller is investigated and it is found that the second scenario would be more efficient.

  6. Kinetic description of flow past a micro-plate

    International Nuclear Information System (INIS)

    Christlieb, Andrew J.; Hitchon, W. Nicholas G.; Boyd, Iain D.; Sun Quanhua

    2004-01-01

    In this work we discuss a novel numerical scheme and present numerical results for the problem of 'high' (of order unity) Knudsen number, Kn=λ/L, low velocity gas flow past a micro-plate. The scheme used here is similar to one employed in the past to examine heat flow, but in order to deal with momentum transport in the vicinity of a plate, new techniques had to be developed. These include a new scheme for finding 'transition probabilities', which eliminates some forms of numerical diffusion, and a method for handling reflections off surfaces which preserves the essential properties of the flow. The purpose of the paper is to present these methods and examine their performance. The method is found to function well, but the results indicate that the collision operator which is employed here must be improved in order to obtain accurate results for the drag. Low speed neutral particle transport, in long mean free path (LMFP) environments, presents challenges for well-established techniques, such as the direct simulation Monte Carlo (DSMC) method. In particular, at low flow velocities, statistical methods suffer from noise that may render them impractical in LMFP environments. Solution of the Boltzmann equation is the alternative to these statistical methods. As computing power increases, Boltzmann-based approaches become more accessible. We discuss here a novel non-statistical (no random numbers are used) kinetic model for particle transport and explore its accuracy and sensitivity to resolution and other details of its implementation. The model is an enhanced version of the transition probability matrix (TPM) method. The results generated by the TPM are compared with the information preservation (IP) method, the Navier-Stokes (NS) slip model and when applicable to DSMC. We provide a qualitative comparison of the models and then we compare the results of the different models for various Kn for flow past a plate. For Kn in the slip flow regime, the TPM, IP and NS

  7. Efficiencies of flat plate solar collectors at different flow rates

    DEFF Research Database (Denmark)

    Chen, Ziqian; Furbo, Simon; Perers, Bengt

    2012-01-01

    Two flat plate solar collectors for solar heating plants from Arcon Solvarme A/S are tested in a laboratory test facility for solar collectors at Technical University of Denmark (DTU). The collectors are designed in the same way. However, one collector is equipped with an ETFE foil between...... the absorber and the cover glass and the other is without ETFE foil. The efficiencies for the collectors are tested at different flow rates. On the basis of the measured efficiencies, the efficiencies for the collectors as functions of flow rate are obtained. The calculated efficiencies are in good agreement...

  8. Characterization and Simulation of a New Design Parallel-Plate Ionization Chamber for CT Dosimetry at Calibration Laboratories

    Science.gov (United States)

    Perini, Ana P.; Neves, Lucio P.; Maia, Ana F.; Caldas, Linda V. E.

    2013-12-01

    In this work, a new extended-length parallel-plate ionization chamber was tested in the standard radiation qualities for computed tomography established according to the half-value layers defined at the IEC 61267 standard, at the Calibration Laboratory of the Instituto de Pesquisas Energéticas e Nucleares (IPEN). The experimental characterization was made following the IEC 61674 standard recommendations. The experimental results obtained with the ionization chamber studied in this work were compared to those obtained with a commercial pencil ionization chamber, showing a good agreement. With the use of the PENELOPE Monte Carlo code, simulations were undertaken to evaluate the influence of the cables, insulator, PMMA body, collecting electrode, guard ring, screws, as well as different materials and geometrical arrangements, on the energy deposited on the ionization chamber sensitive volume. The maximum influence observed was 13.3% for the collecting electrode, and regarding the use of different materials and design, the substitutions showed that the original project presented the most suitable configuration. The experimental and simulated results obtained in this work show that this ionization chamber has appropriate characteristics to be used at calibration laboratories, for dosimetry in standard computed tomography and diagnostic radiology quality beams.

  9. An experimental setup for the study of the steady air flow in a diesel engine chamber

    Directory of Open Access Journals (Sweden)

    Montanero José María

    2012-04-01

    Full Text Available We present an experimental setup for studying the steady air flow in a diesel engine chamber. An engine block containing the inlet manifold was placed on a test bench. A steady air stream crossed the inlet manifold and entered a glass chamber driven by a fan. A PIV system was set up around the bench to measure the in-chamber flow. An air spray gun was used as seed generator to producing sub-millimeter droplets, easily dragged by the air stream. Images of the in-flow chamber were acquired in the course of the experiments, and processed to measure the velocity field. The pressure drop driven the air current and the mass flow rate were also measured.

  10. Flow influence on a mode of flow choking in the airfoil cascade of the thin plates

    Directory of Open Access Journals (Sweden)

    Л.Г. Волянська

    2005-01-01

    Full Text Available  Flow of viscous compressible gas is considered in the airfoil cascade of the thin plates with great negative angle of attack. Influence of wall boundary layer upon a mode of  flow choking in the airfoil cascade is estimated in the article.

  11. Circulation shedding in viscous starting flow past a flat plate

    International Nuclear Information System (INIS)

    Nitsche, Monika; Xu, Ling

    2014-01-01

    Numerical simulations of viscous flow past a flat plate moving in the direction normal to itself reveal details of the vortical structure of the flow. At early times, most of the vorticity is attached to the plate. This paper introduces a definition of the shed circulation at all times and shows that it indeed represents vorticity that separates and remains separated from the plate. During a large initial time period, the shed circulation satisfies the scaling laws predicted for self-similar inviscid separation. Various contributions to the circulation shedding rate are presented. The results show that during this initial time period, viscous diffusion of vorticity out of the vortex is significant but appears to be independent of the value of the Reynolds number. At later times, the departure of the shed circulation from its large Reynolds number behaviour is significantly affected by diffusive loss of vorticity through the symmetry axis. A timescale is proposed that describes when the viscous loss through the axis becomes relevant. The simulations provide benchmark results to evaluate simpler separation models such as point vortex and vortex sheet models. A comparison with vortex sheet results is included. (paper)

  12. Experimental Studies on the Effects of Thermal Bumps in the Flow-Field around a Flat Plate using a Hypersonic Wind Tunnel

    Science.gov (United States)

    2012-07-01

    Bakelite Hylem F1361, which is a thermosetting plastic consisting of a medium weave fabric reinforced laminate with Melamine resin binder. This composite...can be used for high-speed flow control. The laser ablation was conducted on the aluminium alloy plate inside a pressure chamber, where the

  13. computational study of Couette flow between parallel plates for steady and unsteady cases

    International Nuclear Information System (INIS)

    Rihan, Y.

    2008-01-01

    Couette flow between parallel plates is a classical problem that has important applications in various industrial processing. In this investigation an analytical solution was obtained to predict the steady and unsteady Couette flow between parallel plates. One of the plates was stationary and the other plate moved with constant velocity. The governing partial differential equations were solved numerically using Crank-Nicolson implicit method to represent the flow behavior of the fluid

  14. Performance of CMS Resistive Plate Chambers in CRAFT and early 2015 collisions at 13 TeV

    CERN Document Server

    CMS Collaboration

    2015-01-01

    Resistive Plate Chambers (RPC) performance results with cosmics data at 3.8 T and p-p collision data at 13 TeV for 2015 are presented. These results include plots of relevant RPC variables such as occupancy, cluster size, efficiency and residuals. RPC cluster size, measured with cosmic rays at 3.8 T during 2015, is presented and compared with 2012 results. During the first long shutdown of the LHC (2013-2014) the CMS muon system has been upgraded with 144 double-gap chambers on the forth forward stations. During the commissioning period, the system has been successfully run and experimental data has been collected and analyzed in details. Occupancy and efficiency results of newly installed chambers using 13 TeV p-p data are reported. The results of the 2015 HV Scan, performed at 0 T magnetic field, are presented and compared with the 2012 HV scan results at 3.8 T. These results are comparable since RPC efficiency is independent of the magnetic field surrounding the chambers.

  15. Preliminary results of Resistive Plate Chambers operated with eco-friendly gas mixtures for application in the CMS experiment

    International Nuclear Information System (INIS)

    Abbrescia, M.; Muhammad, S.; Saviano, G.; Auwegem, P. Van; Cauwenbergh, S.; Tytgat, M.; Benussi, L.; Bianco, S.; Passamonti, L.; Pierluigi, D.; Piccolo, D.; Primavera, F.; Russo, A.; Ferrini, M.

    2016-01-01

    The operations of Resistive Plate Chambers in LHC experiments require Fluorine based (F-based) gases for optimal performance. Recent European regulations demand the use of environmentally unfriendly F-based gases to be limited or banned. In view of the CMS experiment upgrade, several tests are ongoing to measure the performance of the detector with these new ecological gas mixtures, in terms of efficiency, streamer probability, induced charge and time resolution. Prototype chambers with readout pads and with the standard CMS electronic setup are under test. In this paper preliminary results on performance of RPCs operated with a potential eco-friendly gas candidate 1,3,3,3-Tetrafluoropropene, commercially known as HFO-1234ze, with CO 2 and CF 3 I based gas mixtures are presented and discussed for the possible application in the CMS experiment.

  16. Preliminary results of Resistive Plate Chambers operated with eco-friendly gas mixtures for application in the CMS experiment

    CERN Document Server

    Abbrescia, Marcello; Benussi, Luigi; Bianco, Stefano; Cauwenbergh, Simon Marc D; Ferrini, Mauro; Muhammad, Saleh; Passamontic, L; Pierluigi, Daniele; Piccolo, Davide; Primavera, Federica; Russo, Alessandro; Savianoc, G; Tytgat, Michael

    2016-01-01

    The operations of Resistive Plate Chambers in LHC experiments require F-based gases for optimal performance. Recent regulations demand the use of environmentally unfriendly F-based gases to be limited or banned. In view of the CMS experiment upgrade several tests are ongoing to measure the performance of the detector in terms of efficiency, streamer probability, induced charge and time resolution. Prototype chambers with readout pads and with the standard cms electronic setup are under test. In this talk preliminary results on performance of RPCs operated with a potential eco-friendly gas candidate 1,3,3,3-Tetrafluoropropene, commercially known as HFO-1234ze and with CO2 based gas mixtures are presented and discussed for the possible application in the CMS experiment.

  17. Preliminary results of Resistive Plate Chambers operated with eco-friendly gas mixtures for application in the CMS experiment

    CERN Document Server

    Abbrescia, M.

    2016-01-01

    The operations of Resistive Plate Chambers in LHC experiments require Fluorine based (F-based) gases for optimal performance. Recent European regulations demand the use of environmentally unfriendly F-based gases to be limited or banned. In view of the CMS experiment upgrade, several tests are ongoing to measure the performance of the detector with these new ecological gas mixtures, in terms of efficiency, streamer probability, induced charge and time resolution. Prototype chambers with readout pads and with the standard CMS electronic setup are under test. In this paper preliminary results on performance of RPCs operated with a potential eco-friendly gas candidate 1,3,3,3-Tetrafluoropropene, commercially known as HFO-1234ze, with CO2 and CF3I based gas mixtures are presented and discussed for the possible application in the CMS experiment.

  18. Stability of unstably stratified shear flow between parallel plates

    Energy Technology Data Exchange (ETDEWEB)

    Fujimura, Kaoru; Kelly, R E

    1987-09-01

    The linear stability of unstably stratified shear flows between two horizontal parallel plates was investigated. Eigenvalue problems were solved numerically by making use of the expansion method in Chebyshev polynomials, and the critical Rayleigh numbers were obtained accurately in the Reynolds number range of (0.01, 100). It was found that the critical Rayleigh number increases with an increase of the Reynolds number. The result strongly supports previous stability analyses except for the analysis by Makino and Ishikawa (J. Jpn. Soc. Fluid Mech. 4 (1985) 148 - 158) in which a decrease of the critical Rayleigh number was obtained.

  19. Stability of unstably stratified shear flow between parallel plates

    International Nuclear Information System (INIS)

    Fujimura, Kaoru; Kelly, R.E.

    1987-01-01

    The linear stability of unstably stratified shear flows between two horizontal parallel plates was investigated. Eigenvalue problems were solved numerically by making use of the expansion method in Chebyshev polynomials, and the critical Rayleigh numbers were obtained accurately in the Reynolds number range of [0.01, 100]. It was found that the critical Rayleigh number increases with an increase of the Reynolds number. The result strongly supports previous stability analyses except for the analysis by Makino and Ishikawa [J. Jpn. Soc. Fluid Mech. 4 (1985) 148 - 158] in which a decrease of the critical Rayleigh number was obtained. (author)

  20. Flow field bipolar plates in a proton exchange membrane fuel cell: Analysis & modeling

    International Nuclear Information System (INIS)

    Kahraman, Huseyin; Orhan, Mehmet F.

    2017-01-01

    Highlights: • Covers a comprehensive review of available flow field channel configurations. • Examines the main design considerations and limitations for a flow field network. • Explores the common materials and material properties used for flow field plates. • Presents a case study of step-by-step modeling for an optimum flow field design. - Abstract: This study investigates flow fields and flow field plates (bipolar plates) in proton exchange membrane fuel cells. In this regard, the main design considerations and limitations for a flow field network have been examined, along with a comprehensive review of currently available flow field channel configurations. Also, the common materials and material properties used for flow field plates have been explored. Furthermore, a case study of step-by-step modeling for an optimum flow field design has been presented in-details. Finally, a parametric study has been conducted with respect to many design and performance parameters in a flow field plate.

  1. Resistive plate chambers for 2013-2014 muon upgrade in CMS at LHC

    International Nuclear Information System (INIS)

    Colafranceschi, S.; Sharma, A.; Chudasama, R.; Pant, L.M.; Mohanty, A.K.; Sehgal, R.; Sehgal, S.T.; Thomas, R.G.; Bhandari, V.; Chand, S.; Kumar, A.; Kumar, S.; Singh, A.; Singh, V.; Aly, S.; Aly, R.; Elkafrawy, T.; Ibrahim, A.; Radi, A.; Sayed, A.

    2014-01-01

    During 2013 and 2014 (Long Shutdown LS1) the CMS experiment is upgrading the forward region installing a fourth layer of RPC detectors in order to complete and improve the muon system performances in the view of the foreseen high luminosity run of LHC. The new two endcap disks consists of 144 double-gap RPC chambers assembled at three different production sites: CERN, Ghent (Belgium) and BARC (India). The chamber components as well as the final detectors are subjected to full series of tests established in parallel at all the production sites. All assembly and test operations have been engineered in order to standardize and improve detector production. In this work the complete chamber construction, quality control procedures and preliminary results will be detailed

  2. Drying of fruits and vegetables using a flat plate solar collector with convective air flow

    International Nuclear Information System (INIS)

    Mansoor, K.K.; Hanif, M.

    2011-01-01

    This paper presents the analysis of drying of different fruits and vegetables dried by a flat plate solar collector developed at the Department of Agricultural Mechanization, Khyber PukhtunKhwa Agricultural University Peshawar, Pakistan. A small flat plate solar collector is designed and tested for its maximum performance in terms of efficiency with different convective flow rates. The collector assembly is divided into two parts. The flat plate solar collector and the drying chamber. The materials used for flat plate solar collector are wood, steel sheet, Insulation materials, and glass sheet as covering material. The insulation box (0.9 x 1.8 x 0.3 meter) is made up of wood of popular and deodar, to be fully isolated with the help of polystyrene. The absorber is black painted v-corrugated steel sheet. Collector has a tilt angle of 34 deg. (Equivalent to the latitude of Peshawar). The covering material is (0.9 x 1.8 meter) and 5 mm thick glass sheet placed at the top of the wooden box. The collector is supported and tilted with the help of a frame made up of iron angled arms. While the drying chamber is a (1 X 0.5 x 0.3 meter) wooden box connected to the outlet duct of the collector with the help of polyvinylchloride pipe. Experiments were conducted different fruits and vegetables and different parameters like moisture lost by the products in each hour, drying rate at each hour of drying, humidity and temperature of the drying chamber. It was observed that the products such as bitter guard and onion were dried in 10 to 2 hours up to moisture content less then 8%. These two product lost 8% to 10% moisture during each hour of drying. While grapes and Green chili are dried in 24 to 25 hours up to moisture content less then 8%. These two products lost 4% to 5% moisture in each hour of drying. The drying rate of all the products dried was very much consistent. It was observed that onion and bitter guard showed a good drying rate of 0.03[g(H/sub 2/O)/g(d.m).cm/ 2 hr] to

  3. Two-phase flow patterns in adiabatic and diabatic corrugated plate gaps

    Science.gov (United States)

    Polzin, A.-E.; Kabelac, S.; de Vries, B.

    2016-09-01

    Correlations for two-phase heat transfer and pressure drop can be improved considerably, when they are adapted to specific flow patterns. As plate heat exchangers find increasing application as evaporators and condensers, there is a need for flow pattern maps for corrugated plate gaps. This contribution presents experimental results on flow pattern investigations for such a plate heat exchanger background, using an adiabatic visualisation setup as well as a diabatic setup. Three characteristic flow patterns were observed in the considered range of two-phase flow: bubbly flow, film flow and slug flow. The occurrence of these flow patterns is a function of mass flux, void fraction, fluid properties and plate geometry. Two different plate geometries having a corrugation angle of 27° and 63°, respectively and two different fluids (water/air and R365mfc liquid/vapor) have been analysed. A flow pattern map using the momentum flux is presented.

  4. Modelling of hot air chamber designs of a continuous flow grain dryer

    DEFF Research Database (Denmark)

    Kjær, Lotte Strange; Poulsen, Mathias; Sørensen, Kim

    2018-01-01

    The pressure loss, flow distribution and temperature distribution of a number of designs of the hot air chamber in a continuous flow grain dryer, were investigated using CFD. The flow in the dryer was considered as steady state, compressible and turbulent. It is essential that the grain...... is uniformly dried as uneven drying can result in damage to the end-product during storage. The original commercial design was modified with new guide vanes at the inlets to reduce the pressure loss and to ensure a uniform flow to the line burner in the hot air chamber. The new guide vane design resulted...... in a 10% reduction in pressure loss and a γ-value of 0.804. Various design changes of the hot air chamber were analysed in terms of pressure loss and temperature distribution with the aim of a temperature variation of 5 K at the outlet ducts. An obstruction design was analysed, which improved mixing...

  5. Long term performance studies of large oil-free bakelite resistive plate chamber

    International Nuclear Information System (INIS)

    Ganai, R.; Roy, A.; Ahammed, Z.; Choudhury, S.; Chattopadhyay, S.; Shiroya, M.K.; Agarwal, K.

    2016-01-01

    Several high energy physics and neutrino physics experiments worldwide require large-size RPCs to cover wide acceptances. The muon tracking systems in the Iron calorimeter (ICAL) experiment in the India based Neutrino Observatory (INO), India and the near detector in Deep Underground Neutrino Experiment (DUNE) at Fermilab are two such examples. A single gap bakelite RPC of dimension 240 cm × 120 cm, with gas gap of 0.2 cm, has been built and tested at Variable Energy Cyclotron Centre, Kolkata, using indigenous materials procured from the local market. No additional lubricant, like oil has been used on the electrode surfaces for smoothening. The chamber is in operation for > 365 days. We have tested the chamber for its long term operation. The leakage current, bulk resistivity, efficiency, noise rate and time resolution of the chamber have been found to be quite stable during the testing peroid. It has shown an efficiency > 95% with an average time resolution of ∼ 0.83 ns at the point of measurement at ∼ 8700 V throughout the testing period. Details of the long term performance of the chamber have been discussed.

  6. Long term performance studies of large oil-free bakelite resistive plate chamber

    Science.gov (United States)

    Ganai, R.; Roy, A.; Shiroya, M. K.; Agarwal, K.; Ahammed, Z.; Choudhury, S.; Chattopadhyay, S.

    2016-09-01

    Several high energy physics and neutrino physics experiments worldwide require large-size RPCs to cover wide acceptances. The muon tracking systems in the Iron calorimeter (ICAL) experiment in the India based Neutrino Observatory (INO), India and the near detector in Deep Underground Neutrino Experiment (DUNE) at Fermilab are two such examples. A single gap bakelite RPC of dimension 240 cm × 120 cm, with gas gap of 0.2 cm, has been built and tested at Variable Energy Cyclotron Centre, Kolkata, using indigenous materials procured from the local market. No additional lubricant, like oil has been used on the electrode surfaces for smoothening. The chamber is in operation for > 365 days. We have tested the chamber for its long term operation. The leakage current, bulk resistivity, efficiency, noise rate and time resolution of the chamber have been found to be quite stable during the testing peroid. It has shown an efficiency > 95% with an average time resolution of ~ 0.83 ns at the point of measurement at ~ 8700 V throughout the testing period. Details of the long term performance of the chamber have been discussed.

  7. Chemical reaction in MHD flow past a vertical plate with mass ...

    African Journals Online (AJOL)

    flow in a vertical double passage channel using Robin boundary conditions. ... the diffusion of a chemically reactive species in a laminar boundary layer flow. ...... hydrodynamic flow past a flat plate will Hall effects, Journal of the Physical.

  8. An open-flow pulse ionization chamber for alpha spectrometry of large-area samples

    International Nuclear Information System (INIS)

    Johansson, L.; Roos, B.; Samuelsson, C.

    1992-01-01

    The presented open-flow pulse ionization chamber was developed to make alpha spectrometry on large-area surfaces easy. One side of the chamber is left open, where the sample is to be placed. The sample acts as a chamber wall and therby defeins the detector volume. The sample area can be as large as 400 cm 2 . To prevent air from entering the volume there is a constant gas flow through the detector, coming in at the bottom of the chamber and leaking at the sides of the sample. The method results in good energy resolution and has considerable applicability in the retrospective radon research. Alpha spectra obtained in the retrospective measurements descend from 210 Po, built up in the sample from the radon daughters recoiled into a glass surface. (au)

  9. Scaling of the flow field in a combustion chamber with a gas–gas injector

    International Nuclear Information System (INIS)

    Xiao-Wei, Wang; Guo-Biao, Cai; Ping, Jin

    2010-01-01

    The scaling of the flow field in a gas–gas combustion chamber is investigated theoretically, numerically and experimentally. To obtain the scaling criterion of the gas–gas combustion flowfield, formulation analysis of the three-dimensional (3D) Navier–Stokes equations for a gaseous multi-component mixing reaction flow is conducted and dimensional analysis on the gas–gas combustion phenomena is also carried out. The criterion implies that the size and the pressure of the gas–gas combustion chamber can be changed. Based on the criterion, multi-element injector chambers with different geometric sizes and at different chamber pressures ranging from 3 MPa to 20 MPa are numerically simulated. A multi-element injector chamber is designed and hot-fire tested at five chamber pressures from 1.64 MPa to 3.68 MPa. Wall temperature measurements are used to understand the similarity of combustion flowfields in the tests. The results have verified the similarities between combustion flowfields under different chamber pressures and geometries, with the criterion applied. (geophysics, astronomy and astrophysics)

  10. First joint test beam of CMS Drift Tubes (DT) and Resistive Plate Chambers (RPC)

    CERN Multimedia

    Paolo Giacomelli

    2001-01-01

    The first full size muon drift tube chamber ever built for the CMS barrel with the final cell design (constructed at CIEMAT, Madrid) was succesfully tested with a muon beam in September 2001 at the Gamma Irradiation Facility (GIF) at CERN. For the first time also both muon detectors for the CMS barrel (DT + RPC) were coupled together. The results of this test were fully succesful and confirmed the excellent performance of both detectors together in a radiation environment.

  11. Entropy Generation on Nanofluid Flow through a Horizontal Riga Plate

    Directory of Open Access Journals (Sweden)

    Tehseen Abbas

    2016-06-01

    Full Text Available In this article, entropy generation on viscous nanofluid through a horizontal Riga plate has been examined. The present flow problem consists of continuity, linear momentum, thermal energy, and nanoparticle concentration equation which are simplified with the help of Oberbeck-Boussinesq approximation. The resulting highly nonlinear coupled partial differential equations are solved numerically by means of the shooting method (SM. The expression of local Nusselt number and local Sherwood number are also taken into account and discussed with the help of table. The physical influence of all the emerging parameters such as Brownian motion parameter, thermophoresis parameter, Brinkmann number, Richardson number, nanoparticle flux parameter, Lewis number and suction parameter are demonstrated graphically. In particular, we conferred their influence on velocity profile, temperature profile, nanoparticle concentration profile and Entropy profile.

  12. Effects of SF$_{6}$ on the avalanche mode operation of a real-sized double-gap resistive plate chamber for the Compact Muon Solenoid experiment

    CERN Document Server

    Ahn Sung Hwan; Hong, B; Hong, S J; Ito, M; Kim, B I; Kim, J H; Kim, Y J; Kim, Y U; Koo, D G; Lee, H W; Lee, K B; Lee, K S; Lee, S J; Lim, J K; Moon, D H; Nam, S K; Park, S; Park, W J; Rhee, J T; Ryu, M S; Shim, H H; Sim, K S; Kang, T I

    2005-01-01

    We present the design and the test, results for a real-sized prototype resistive plate chamber by using cosmic-ray muons for the forward region of the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC). In particular, we investigate the effects of adding SF/sub 6/ to the gas mixture for the avalanche mode operation of a resistive plate chamber. A small fraction of SF/sub 6/ is very effective in suppressing streamer signals in a resistive plate chamber. The shapes of the muon detection efficiency and the muon cluster size remain similar, but are shifted to higher operating voltage by SF/sub 6/. The noise cluster rate and size are not influenced by SF/sub 6/.

  13. Highly conductive, multi-layer composite precursor composition to fuel cell flow field plate or bipolar plate

    Science.gov (United States)

    Jang, Bor Z [Centerville, OH; Zhamu, Aruna [Centerville, OH; Guo, Jiusheng [Centerville, OH

    2011-02-15

    This invention provides a moldable, multiple-layer composite composition, which is a precursor to an electrically conductive composite flow field plate or bipolar plate. In one preferred embodiment, the composition comprises a plurality of conductive sheets and a plurality of mixture layers of a curable resin and conductive fillers, wherein (A) each conductive sheet is attached to at least one resin-filler mixture layer; (B) at least one of the conductive sheets comprises flexible graphite; and (C) at least one resin-filler mixture layer comprises a thermosetting resin and conductive fillers with the fillers being present in a sufficient quantity to render the resulting flow field plate or bipolar plate electrically conductive with a conductivity no less than 100 S/cm and thickness-direction areal conductivity no less than 200 S/cm.sup.2.

  14. Beam test results of the first full-scale prototype of CMS RE 1/2 resistive plate chamber

    International Nuclear Information System (INIS)

    Ying Jun; Ban Yong; Ye Yanlin; Cai Jianxin; Qian Sijin; Wang Quanjin; Liu Hongtao

    2005-01-01

    The authors reported the muon beam test results of the first full-scale prototype of CMS RE 1/2 Resistive Plate Chamber (RPC). The bakelite surface is treated using a special technology without oil to make it smooth enough. The full scale RE 1/2 RPC with honeycomb supporting frame is strong and thin enough to be fitted to the limited space of CMS design for the inner Forward RPC. The muon beam test was performed at CERN Gamma Irradiation Facility (GIF). The detection efficiency of this full scale RPC prototype is >95% even at very high irradiation background. The time resolution (less than 1.2 ns) and spatial resolution are satisfactory for the muon trigger device in future CMS experiments. The noise rate is also calculated and discussed

  15. Signal enhancement due to high-Z nanofilm electrodes in parallel plate ionization chambers with variable microgaps.

    Science.gov (United States)

    Brivio, Davide; Sajo, Erno; Zygmanski, Piotr

    2017-12-01

    We developed a method for measuring signal enhancement produced by high-Z nanofilm electrodes in parallel plate ionization chambers with variable thickness microgaps. We used a laboratory-made variable gap parallel plate ionization chamber with nanofilm electrodes made of aluminum-aluminum (Al-Al) and aluminum-tantalum (Al-Ta). The electrodes were evaporated on 1 mm thick glass substrates. The interelectrode air gap was varied from 3 μm to 1 cm. The gap size was measured using a digital micrometer and it was confirmed by capacitance measurements. The electric field in the chamber was kept between 0.1 kV/cm and 1 kV/cm for all the gap sizes by applying appropriate compensating voltages. The chamber was exposed to 120 kVp X-rays. The current was measured using a commercial data acquisition system with temporal resolution of 600 Hz. In addition, radiation transport simulations were carried out to characterize the dose, D(x), high-energy electron current, J(x), and deposited charge, Q(x), as a function of distance, x, from the electrodes. A deterministic method was selected over Monte Carlo due to its ability to produce results with 10 nm spatial resolution without stochastic uncertainties. Experimental signal enhancement ratio, SER(G) which we defined as the ratio of signal for Al-air-Ta to signal for Al-air-Al for each gap size, was compared to computations. The individual contributions of dose, electron current, and charge deposition to the signal enhancement were determined. Experimental signals matched computed data for all gap sizes after accounting for several contributions to the signal: (a) charge carrier generated via ionization due to the energy deposited in the air gap, D(x); (b) high-energy electron current, J(x), leaking from high-Z electrode (Ta) toward low-Z electrode (Al); (c) deposited charge in the air gap, Q(x); and (d) the decreased collection efficiency for large gaps (>~500 μm). Q(x) accounts for the electrons below 100 eV, which are

  16. Direct numerical simulation of laminar-turbulent flow over a flat plate at hypersonic flow speeds

    Science.gov (United States)

    Egorov, I. V.; Novikov, A. V.

    2016-06-01

    A method for direct numerical simulation of a laminar-turbulent flow around bodies at hypersonic flow speeds is proposed. The simulation is performed by solving the full three-dimensional unsteady Navier-Stokes equations. The method of calculation is oriented to application of supercomputers and is based on implicit monotonic approximation schemes and a modified Newton-Raphson method for solving nonlinear difference equations. By this method, the development of three-dimensional perturbations in the boundary layer over a flat plate and in a near-wall flow in a compression corner is studied at the Mach numbers of the free-stream of M = 5.37. In addition to pulsation characteristic, distributions of the mean coefficients of the viscous flow in the transient section of the streamlined surface are obtained, which enables one to determine the beginning of the laminar-turbulent transition and estimate the characteristics of the turbulent flow in the boundary layer.

  17. Determination of absorbed dose to water from a miniature kilovoltage x-ray source using a parallel-plate ionization chamber

    Science.gov (United States)

    Watson, Peter G. F.; Popovic, Marija; Seuntjens, Jan

    2018-01-01

    Electronic brachytherapy sources are widely accepted as alternatives to radionuclide-based systems. Yet, formal dosimetry standards for these devices to independently complement the dose protocol provided by the manufacturer are lacking. This article presents a formalism for calculating and independently verifying the absorbed dose to water from a kV x-ray source (The INTRABEAM System) measured in a water phantom with an ionization chamber calibrated in terms of air-kerma. This formalism uses a Monte Carlo (MC) calculated chamber conversion factor, CQ , to convert air-kerma in a reference beam to absorbed dose to water in the measurement beam. In this work CQ was determined for a PTW 34013 parallel-plate ionization chamber. Our results show that CQ was sensitive to the chamber plate separation tolerance, with differences of up to 15%. CQ was also found to have a depth dependence which varied with chamber plate separation (0 to 10% variation for the smallest and largest cavity height, over 3 to 30 mm depth). However for all chamber dimensions investigated, CQ was found to be significantly larger than the manufacturer reported value, suggesting that the manufacturer recommended method of dose calculation could be underestimating the dose to water.

  18. Damping parameter study of a perforated plate with bias flow

    Science.gov (United States)

    Mazdeh, Alireza

    role of LES for research studies concerned with damping properties of liners is limited to validation of other empirical or theoretical approaches. This research has shown that LES can go beyond that and can be used for performing parametric studies to characterize the sensitivity of acoustic properties of multi--perforated liners to the changes in the geometry and flow conditions and be used as a tool to design acoustic liners. The conducted research provides an insightful understanding about the contribution of different flow and geometry parameters such as perforated plate thickness, aperture radius, porosity factors and bias flow velocity. While the study agrees with previous observations obtained by analytical or experimental methods, it also quantifies the impact from these parameters on the acoustic impedance of perforated plate, a key parameter to determine the acoustic performance of any system. The conducted study has also explored the limitations and capabilities of commercial tool when are applied for performing simulation studies on damping properties of liners. The overall agreement between LES results and previous studies proves that commercial tools can be effectively used for these applications under certain conditions.

  19. Test of freonless operation of resistive plate chambers with glass electrodes--1 mm gas gap vs 2 mm gas gap

    CERN Document Server

    Sakaue, H; Takahashi, T; Teramoto, Y

    2002-01-01

    Non-freon gas mixtures (Ar/iso-C sub 4 H sub 1 sub 0) were tested as the chamber gas for 1 and 2 mm gas gap Resistive Plate Chambers (RPCs) with float glass as the resistive electrodes, operated in the streamer mode. With the narrower (1 mm) gas gap, streamer charge is reduced (approx 1/3), which reduces the dead time (and dead area), associated with each streamer, improving the detection efficiency. The best performance was obtained for two cases: Ar/iso-C sub 4 H sub 1 sub 0 =50/50 and 60/40. For the 50/50 mixture, a detection efficiency of better than 98% was obtained for the 1 mm gap RPC, while the efficiency was 95% for the 2 mm gap RPC, each operated as a double-gap RPC. The measured time resolution (rms) was 1.45+-0.05 (2.52+-0.09) ns for the 1 (2) mm gap RPC for the 50/50 mixture.

  20. Bifurcation of cubic nonlinear parallel plate-type structure in axial flow

    International Nuclear Information System (INIS)

    Lu Li; Yang Yiren

    2005-01-01

    The Hopf bifurcation of plate-type beams with cubic nonlinear stiffness in axial flow was studied. By assuming that all the plates have the same deflections at any instant, the nonlinear model of plate-type beam in axial flow was established. The partial differential equation was turned into an ordinary differential equation by using Galerkin method. A new algebraic criterion of Hopf bifurcation was utilized to in our analysis. The results show that there's no Hopf bifurcation for simply supported plate-type beams while the cantilevered plate-type beams has. At last, the analytic expression of critical flow velocity of cantilevered plate-type beams in axial flow and the purely imaginary eigenvalues of the corresponding linear system were gotten. (authors)

  1. Phakic iris-fixated intraocular lens placement in the anterior chamber: effects on aqueous flow.

    Science.gov (United States)

    Repetto, Rodolfo; Pralits, Jan O; Siggers, Jennifer H; Soleri, Paolo

    2015-05-01

    Phakic intraocular lenses (pIOLs) are used for correcting vision; in this paper we investigate the fluid dynamical effects of an iris-fixated lens in the anterior chamber. In particular, we focus on changes in the wall shear stress (WSS) on the cornea and iris, which could be responsible for endothelial and pigment cell loss, respectively, and also on the possible increase of the intraocular pressure, which is known to correlate with the incidence of secondary glaucoma. We use a mathematical model to study fluid flow in the anterior chamber in the presence of a pIOL. The governing equations are solved numerically using the open source software OpenFOAM. We use an idealized standard geometry for the anterior chamber and a realistic geometric description of the pIOL. We consider separately the main mechanisms that produce fluid flow in the anterior chamber. The numerical simulations allow us to obtain a detailed description of the velocity and pressure distribution in the anterior chamber, and indicated that implantation of the pIOL significantly modifies the fluid dynamics in the anterior chamber. However, lens implantation has negligible influence on the intraocular pressure and does not produce a significant increase of the shear stress on the cornea, while the shear stress on the iris, although increased, is not enough to cause detachment of cells. We conclude that alterations in the fluid dynamics in the anterior chamber as a result of lens implantation are unlikely to be the cause of medical complications associated with its use.

  2. Design of the Flow Plates for a Dual Cooled Fuel Assembly

    International Nuclear Information System (INIS)

    Kim, Jae Yong; Yoon, Kyung Ho; Lee, Young Ho; Lee, Kang Hee; Kim, Hyung Kyu

    2009-01-01

    In a dual cooled fuel assembly, the array and position of fuels are changed from those of a conventional PWR fuel assembly to achieve a power uprating. The flow plate provides flow holes to direct the heated coolant into/out of the fuel assembly and structural intensity to insure that the fuel rod is axially restrained within the spacer grids. So, flow plates of top/bottom end pieces (TEP/BEP) have to be modified into proper shape. Because the flow holes' area of a flow plate affects pressure drop, the flow holes' area must be larger than/equal to that of conventional flow plates. And design criterion of the TEP/BEP says that the flow plate should withstand a 22.241 kN axial load during handling lest a calculated stress intensity should exceed the Condition I allowable stress. In this paper, newly designed flow plates of a TEP/BEP are suggested and stress analysis is conducted to evaluate strength robustness of the flow plates for the dual cooled fuel assembly

  3. Lean premixed reacting flows with swirl and wall-separation zones in a contracting chamber

    Science.gov (United States)

    Zhang, Yuxin; Rusak, Zvi; Wang, Shixiao

    2017-11-01

    Low Mach number lean premixed reacting swirling flows with wall-separation zones in a contracting circular finite-length open chamber are studied. Assuming a complete reaction with high activation energy and chemical equilibrium behind the reaction zone, a nonlinear partial differential equation is derived for the solution of the flow stream function behind the reaction zone in terms of the inlet total enthalpy for a reacting flow, specific entropy and the circulation functions. Bifurcation diagrams of steady flows are described as the inlet swirl level is increased at fixed chamber contraction and reaction heat release. The approach is applied to an inlet solid-body rotation flow with constant profiles of the axial velocity, temperature and mixture reactant mass fraction. The computed results provide predictions of the critical inlet swirl levels for the first appearance of wall-separation states and for the size of the separation zone as a function of the inlet swirl ratio, Mach number, chamber contraction and heat release of the reaction. The methodology developed in this paper provides a theoretical feasibility for the development of the technology of swirl-assisted combustion where the reaction zone is supported and stabilized by a wall-separation zone.

  4. SIZE REDUCTION OF ELECTROSTATIC PRECIPITATOR CHAMBER BY MODIFICATION OF GAS FLOW DISTRIBUTION

    Directory of Open Access Journals (Sweden)

    Beata Sładkowska-Rybka

    2014-10-01

    Full Text Available Electrostatic precipitators (ESP are one of the most effective devices for particulate emission control, removing from the exhaust gases even 99,9 % of dust particles. The collection efficiency of the ESP depends on a number of factors: mechanical design and electrical operating parameters, physical and chemical properties of cleaned gas, characteristic of dust particles suspended in the gas. Among the most important factors affecting the ESP effectiveness, the velocity and the distribution of gas flow in the ESP chamber should be also indicated. Significant increase in ESP efficiency is possible thanks to the application of Skewed Gas Flow Technology (SGFT. In this paper the computer simulations results are shown. Authors investigated the possibility of ESP chamber size reduction by modification of gas flow distribution.

  5. Test Methodologies for Hydrogen Sensor Performance Assessment: Chamber vs. Flow Through Test Apparatus: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Buttner, William J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Hartmann, Kevin S [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Schmidt, Kara [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Cebolla, Rafeal O [Joint Research Centre, Petten, the Netherlands; Weidner, Eveline [Joint Research Centre, Petten, the Netherlands; Bonato, Christian [Joint Research Centre, Petten, the Netherlands

    2017-11-06

    Certification of hydrogen sensors to standards often prescribes using large-volume test chambers [1, 2]. However, feedback from stakeholders such as sensor manufacturers and end-users indicate that chamber test methods are often viewed as too slow and expensive for routine assessment. Flow through test methods potentially are an efficient, cost-effective alternative for sensor performance assessment. A large number of sensors can be simultaneously tested, in series or in parallel, with an appropriate flow through test fixture. The recent development of sensors with response times of less than 1s mandates improvements in equipment and methodology to properly capture the performance of this new generation of fast sensors; flow methods are a viable approach for accurate response and recovery time determinations, but there are potential drawbacks. According to ISO 26142 [1], flow through test methods may not properly simulate ambient applications. In chamber test methods, gas transport to the sensor can be dominated by diffusion which is viewed by some users as mimicking deployment in rooms and other confined spaces. Alternatively, in flow through methods, forced flow transports the gas to the sensing element. The advective flow dynamics may induce changes in the sensor behaviour relative to the quasi-quiescent condition that may prevail in chamber test methods. One goal of the current activity in the JRC and NREL sensor laboratories [3, 4] is to develop a validated flow through apparatus and methods for hydrogen sensor performance testing. In addition to minimizing the impact on sensor behaviour induced by differences in flow dynamics, challenges associated with flow through methods include the ability to control environmental parameters (humidity, pressure and temperature) during the test and changes in the test gas composition induced by chemical reactions with upstream sensors. Guidelines on flow through test apparatus design and protocols for the evaluation of

  6. Predicting the onset of dynamic instability of a cylindrical plate under axial flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Marcum, W.R., E-mail: marcumw@engr.orst.edu [Oregon State University, Department of Nuclear Engineering and Radiation Health Physics, 116 Radiation Center, Corvallis, OR 97330 (United States); Woods, B.G. [Oregon State University, Department of Nuclear Engineering and Radiation Health Physics, 116 Radiation Center, Corvallis, OR 97330 (United States)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer A semi-numerical flow induced vibration model is developed of a cylindrical plate. Black-Right-Pointing-Pointer Test case results are presented and agree well with previous studies data. Black-Right-Pointing-Pointer The model identifies a relationship between forces and the plate natural frequency. - Abstract: The dynamic mechanical stability of a single cylindrical plate under flow conditions is considered herein. Numerous plate-type research reactors such as the Advanced Test Reactor (ATR) located at the Idaho National Laboratory (INL) comprise fuel elements which contain arrays of concentrically aligned cylindrical plates. Several of these reactors are licensed to operate at extreme heat fluxes; as a corollary their hydraulic designs require large flow rates sufficient to remove this heat. These flow rates may reach superficial velocities upwards of 15 m/s through individual flow channels. Given that fuel plates typically found in such research reactors are relatively long ({approx}1.2573 m), wide ({approx}0.1397 m), and extremely thin ({approx}0.00127 m) concern is drawn toward the susceptibility of flow induced vibration (FIV). In an attempt to gain a more comprehensive understanding toward the dynamic mechanical limit of stability of cylindrical plates, a FIV model was developed using semi-numerical methods. The FIV model was developed in two separate modules; a plate stability module, and a flow module. These modules were then coupled together to produce a FIV model. In this study, a set of test cases are presented on the plate stability module under free vibration conditions, comparing well against known available information from previous studies. Results are similarly presented on the flow module and compared against a RELAP5-3D model. Lastly, results of these coupled modules are presented and discussion is given toward the relationship between plate natural frequency, geometry, and plate membrane pressures.

  7. The effect of plate thickness, surface tension and fluid flow on detachment of drops from a plate

    NARCIS (Netherlands)

    Lexmond, A.S.; Geld, C.W.M. van der

    2005-01-01

    The pinch-off of drops from the downstream end of plates is an important re-entrainment mechanism of condensate in compact condensers. The present experimental study complements a previous one [A.S. Lexmond, C.W.M. van der Geld, The effect of fluid flow on detachment of drops from the downstream end

  8. Flow over a cylinder with a hinged-splitter plate

    Science.gov (United States)

    Shukla, S.; Govardhan, R. N.; Arakeri, J. H.

    2009-05-01

    Previous work on rigid splitter plates in the wake of a bluff body has shown that the primary vortex shedding can be suppressed for sufficiently long splitter plates. In the present work, we study the problem of a hinged-splitter plate in the wake of a circular cylinder. The splitter plate can rotate about the hinge at the base of the cylinder due to the unsteady fluid forces acting on it, and hence the communication between the two sides of the wake is not totally disrupted as in the rigid splitter plate case. In our study, we investigate this problem in the limit where the stiffness and internal damping associated with the hinge are negligible, and the mass ratio of the splitter plate is small. The experiments show that the splitter plate oscillations increase with Reynolds numbers at low values of Re, and are found to reach a saturation amplitude level at higher Re, Re>4000. This type of saturation amplitude level that appears to continue indefinitely with Re, appears to be related to the fact that there is no structural restoring force, and has been observed previously for transversely oscillating cylinders with no restoring force. In the present case, the saturation tip amplitude level can be up to 0.45D, where D is the cylinder diameter. For this hinged-rigid splitter plate case, it is found that the splitter plate length to cylinder diameter ratio (L/D) is crucial in determining the character and magnitude of the oscillations. For small splitter plate lengths (L/D⩽3.0), the oscillations appear to be nearly periodic with tip amplitudes of about 0.45D nearly independent of L/D. The nondimensional oscillation frequencies (fD/U) on the other hand are found to continuously vary with L/D from fD/U≈0.2 at L/D=1 to fD/U≈0.1 at L/D=3. As the splitter plate length is further increased beyond L/D⩾4.0, the character of the splitter plate oscillations suddenly changes. The oscillations become aperiodic with much smaller amplitudes. In this long splitter plate

  9. Experimental investigation of the unsteady two-phase flow through perforated plates

    International Nuclear Information System (INIS)

    Tartaglia, G.P.

    1985-07-01

    The coolant flow across the perforated dip-plate during a hypothetical core disruptive accident (HCDA) in a liquid metal fast breeder reactor was simulated in a one-dimensional model. Experiments with a water-air mixture as fluid were run by varying the following parameters: geometry of the dip-plate (perforation ratio, number of the holes), height of the fluid head over the dip-plate, air volumetric fraction, size of the air bubbles, acceleration of the fluid. The pressure drop across the dip-plate, the forces acting on the dip-plate and on the upper plate, acceleration and displacement of the piston, the air volumetric fraction and the size of the air bubbles were measured in a wide range of Strouhal and acceleration numbers. The flow pattern downstream the dip-plate was filmed with a high-speed camera. The following correlations were investigated: resistance coefficients as a function of the acceleration and Strouhal number, time delay of the force on the upper plate as a function of the cavitation number, and forces and impulses acting on the upper plate compared with those acting on the dip-plate. Finally, using high-speed film pictures, the formation of fluid jets downstream the dip-plate was investigated. The following relations were obtained: displacement of the mixture surface and of the jets as a function of the perforation ratio and of the air volumetric fraction, and cavitation volume as a function of the cavitation number. (orig.) [de

  10. Laminated exfoliated graphite composite-metal compositions for fuel cell flow field plate or bipolar plate applications

    Science.gov (United States)

    Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z

    2014-05-20

    An electrically conductive laminate composition for fuel cell flow field plate or bipolar plate applications. The laminate composition comprises at least a thin metal sheet having two opposed exterior surfaces and a first exfoliated graphite composite sheet bonded to the first of the two exterior surfaces of the metal sheet wherein the exfoliated graphite composite sheet comprises: (a) expanded or exfoliated graphite and (b) a binder or matrix material to bond the expanded graphite for forming a cohered sheet, wherein the binder or matrix material is between 3% and 60% by weight based on the total weight of the first exfoliated graphite composite sheet. Preferably, the first exfoliated graphite composite sheet further comprises particles of non-expandable graphite or carbon in the amount of between 3% and 60% by weight based on the total weight of the non-expandable particles and the expanded graphite. Further preferably, the laminate comprises a second exfoliated graphite composite sheet bonded to the second surface of the metal sheet to form a three-layer laminate. Surface flow channels and other desired geometric features can be built onto the exterior surfaces of the laminate to form a flow field plate or bipolar plate. The resulting laminate has an exceptionally high thickness-direction conductivity and excellent resistance to gas permeation.

  11. Effects of gas chamber geometry and gas flow on the neutron production in a fast plasma focus neutron source

    International Nuclear Information System (INIS)

    Tarifeño-Saldivia, Ariel; Soto, Leopoldo

    2014-01-01

    This work reports that gas chamber geometry and gas flow management substantially affect the neutron production of a repetitive fast plasma focus. The gas flow rate is the most sensitive parameter. An appropriate design of the gas chamber combined with a suitable flow-rate management can lead to improvements in the neutron production of one order of magnitude working in a fast repetitive mode. (paper)

  12. Recent results and performance of the multi-gap resistive plate chambers network for the EEE Project

    Science.gov (United States)

    Abbrescia, M.; Avanzini, C.; Baldini, L.; Baldini Ferroli, R.; Batignani, G.; Bencivenni, G.; Bossini, E.; Chiavassa, A.; Cicalò, C.; Cifarelli, L.; Coccia, E.; Corvaglia, A.; De Gruttola, D.; De Pasquale, S.; Di Giovanni, A.; D`Incecco, M.; Dreucci, M.; Fabbri, F. L.; Fattibene, E.; Ferraro, A.; Frolov, V.; Galeotti, P.; Garbini, M.; Gemme, G.; Gnesi, I.; Grazzi, S.; Gustavino, C.; Hatzifotiadou, D.; La Rocca, P.; Licciulli, F.; Maggiora, A.; Maragoto Rodriguez, O.; Maron, G.; Martelli, B.; Mazziotta, M. N.; Miozzi, S.; Nania, R.; Noferini, F.; Nozzoli, F.; Panareo, M.; Panetta, M. P.; Paoletti, R.; Park, W.; Perasso, L.; Pilo, F.; Piragino, G.; Riggi, F.; Righini, G. C.; Sartorelli, G.; Scapparone, E.; Schioppa, M.; Scribano, A.; Selvi, M.; Serci, S.; Siddi, E.; Squarcia, S.; Stori, L.; Taiuti, M.; Terreni, G.; Visnyei, O. B.; Vistoli, M. C.; Votano, L.; Williams, M. C. S.; Zani, S.; Zichichi, A.; Zuyeusky, R.

    2016-11-01

    The Extreme Energy Events (EEE) Project is devoted to the study of Extensive Atmospheric Showers through a network of muon telescopes, installed in High Schools, with the further aim of introducing young students to particle and astroparticle physics. Each telescope is a tracking detector composed of three Multi-gap Resistive Plate Chambers (MRPC) with an active area of 1.60 × 0.80 m2. Their characteristics are similar to the ones built for the Time Of Flight array of the ALICE Experimentat LHC . The EEE Project started with a few pilot towns, where the telescopes have been taking data since 2008, and it has been constantly extended, reaching at present more than 50 MRPCs telescopes. They are spread across Italy with two additional stations at CERN, covering an area of around 3 × 105 km2, with a total surface area for all the MRPCs of 190 m2. A comprehensive description of the MRPCs network is reported here: efficiency, time and spatial resolution measured using cosmic rays hitting the telescopes. The most recent results on the detector and physics performance from a series of coordinated data acquisition periods are also presented.

  13. Performance of a resistive plate chamber equipped with a new prototype of amplified front-end electronics

    CERN Document Server

    Marchisone, Massimiliano

    2016-01-01

    ALICE is the LHC experiment dedicated to the study of heavy-ion collisions. At forward rapidity a muon spectrometer detects muons from low mass mesons, quarkonia, open heavy-flavor hadrons as well as weak bosons. A muon selection based on transverse momentum is made by a trigger system composed of 72 resistive plate chambers (RPCs). For the LHC Run 1 and the ongoing Run 2 the RPCs have been equipped with a non-amplified FEE called ADULT. However, in view of an increase in luminosity expected for Run 3 (2021-2023) the possibility to use an amplified FEE has been explored in order to improve the counting rate limitation and to prevent the aging of the detector, by reducing the charge per hit. A prototype of this new electronics (FEERIC) has been developed and tested first with cosmic rays before equipping one RPC in the ALICE cavern with it. In this talk the most important performance indicators - efficiency, dark current, dark rate, cluster size and total charge - of an RPC equipped with this new FEE will be r...

  14. Energy flow analysis of out-of-plane vibration in coplanar coupled finite Mindlin plates

    Directory of Open Access Journals (Sweden)

    Young-Ho Park

    2015-01-01

    Full Text Available : In this paper, an Energy Flow Analysis (EFA for coplanar coupled Mindlin plates was performed to estimate their dynamic responses at high frequencies. Mindlin plate theory can consider the effects of shear distortion and rotatory inertia, which are very important at high frequencies. For EFA for coplanar coupled Mindlin plates, the wave transmission and reflection relationship for progressing out-of-plane waves (out-of-plane shear wave, bending dominant flexural wave, and shear dominant flexural wave in coplanar coupled Mindlin plates was newly derived. To verify the validity of the EFA results, numerical analyses were performed for various cases where coplanar coupled Mindlin plates are excited by a harmonic point force, and the energy flow solutions for coplanar coupled Mindlin plates were compared with the classical solutions in the various conditions.

  15. Investigation and performance tests of a new parallel plate ionization chamber with double sensitive volume for measuring diagnostic X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Sharifi, B., E-mail: babak_sharifi88@yahoo.com [Graduate University of Advanced Technology, Kerman (Iran, Islamic Republic of); Zamani Zeinali, H. [Application of Radiation Research School, Nuclear Science and Technology Research Institute, AEOI, Karaj (Iran, Islamic Republic of); Soltani, J.; Negarestani, A. [Graduate University of Advanced Technology, Kerman (Iran, Islamic Republic of); Shahvar, A. [Application of Radiation Research School, Nuclear Science and Technology Research Institute, AEOI, Karaj (Iran, Islamic Republic of)

    2015-01-11

    Medical diagnostic equipment, like diagnostic radiology and mammography require a dosimeter with high accuracy for dosimetry of the diagnostic X-ray beam. Ionization chambers are suitable instruments for dosimetry of diagnostic-range X-ray beams because of their appropriate response and high reliability. This work introduces the design and fabrication of a new parallel plate ionization chamber with a PMMA body, graphite-coated PMMA windows (0.5 mm thick) and a graphite-foil central electrode (0.1 mm thick, 0.7 g/cm{sup 3} dense). This design improves upon the response characteristics of existing designs through the specific choice of materials as well as the appropriate size and arrangement of the ionization chamber components. The results of performance tests conducted at the Secondary Standard Dosimetry laboratory in Karaj-Iran demonstrated the short and long-term stability, the low leakage current, the low directional dependence, and the high ion collection efficiency of the design. Furthermore, the FLUKA Monte Carlo simulations confirmed the low effect of central electrode on this new ionization chamber response. The response characteristics of the parallel plate ionization chamber presented in this work makes the instrument suitable for use as a standard dosimeter in laboratories.

  16. Experimental investigation of the unsteady one-phase flow through perforated plates

    International Nuclear Information System (INIS)

    Casadei, F.

    1982-07-01

    The flow of the coolant through the perforated dip-plate during a hypothetical core-disruptive accident in a sodium-cooled fast breeder reactor was simulated in a one-dimensional model. Several experiments with water as fluid and with various perforation ratios of the dip-plate and different initial heights of the fluid head over the dip plate were run. The pressure drop through the dip-plate and the forces acting on the dip-plate and on the upper plug of the reactor vessel in a wide range of the Reynolds and Strouhal numbers were measured. The flow pattern downstreams the perforated plate was filmed with high-speed cameras. The resistance coefficients for the unsteady flow of the coolant through the perforated plate were obtained as a function of the acceleration. The forces acting on the upper plug and their time integral were compared with those acting on the dip-plate. Finally, using the high-speed film pictures the formation of fluid jets downstream the dip-plate was investigated. (orig.) [de

  17. Theoretical study of flow ripple for an aviation axial-piston pump with damping holes in the valve plate

    Directory of Open Access Journals (Sweden)

    Guan Changbin

    2014-02-01

    Full Text Available Based on the structure of a certain type of aviation axial-piston pump’s valve plate which adopts a pre-pressurization fluid path (consisting a damping hole, a buffer chamber, and an orifice to reduce flow ripple, a single-piston model of the aviation axial-piston pump is presented. This single-piston model comprehensively considers fluid compressibility, orifice restriction effect, fluid resistance in the capillary tube, and the leakage flow. Besides, the instantaneous discharge areas used in the single-piston model have been calculated in detail. Based on the single-piston model, a multi-piston pump model has been established according to the simple hydraulic circuit. The single- and multi-piston pump models have been realized by the S-function in Matlab/Simulink. The developed multi-piston pump model has been validated by being compared with the numerical result by computational fluid dynamic (CFD. The effects of the pre-pressurization fluid path on the flow ripple and the instantaneous pressure in the piston chamber have been studied and optimized design recommendations for the aviation axial-piston pump have been given out.

  18. Heat transfer in flow past a continuously moving porous flat plate with heat flux

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, T.V.R.; Sarma, Y.V.B.

    The analysis of the heat transfer in flow past a continuously moving semi-infinite plate in the presence of suction/ injection with heat flux has been presented. Similarity solutions have been derived and the resulting equations are integrated...

  19. Unsteady free convection MHD flow between two heated vertical parallel plates in induced magnetic field

    International Nuclear Information System (INIS)

    Chakraborty, S.; Borkakati, A.K.

    1999-01-01

    An unsteady viscous incompressible free convection flow of an electrically conducting fluid between two heated vertical parallel plates is considered in presence of a uniform magnetic field applied transversely to the flow. The approximate analytical solutions for velocity, induced field and temperature distributions are obtained for small and large magnetic Reynolds number. The skin-friction on the two plates are obtained and plotted graphically. The problem is extended for thermometric case. (author)

  20. Preliminary test of 5-gap glass multi-gap resistive plate chamber for photon detection for time of flight positron emission tomography (TOF-PET) imaging

    International Nuclear Information System (INIS)

    Ganai, R.; Mondal, M.; Mehta, S.; Chattopadhyay, S.

    2016-01-01

    Multi-gap Resistive Plate Chamber (MRPC) is a type of gas detector which uses constant and uniform electric field in between several high resistive electrodes and works on the principle of gas ionisation. In MRPC a particular gas gap is divided into several parts with the help of thin high resistive electrodes. Division of the gas gap helps to improve the time resolution of the detector significantly. MRPCs with time resolution of ∼15 ps have been reported

  1. Control of the flow in the annular region of a shrouded cylinder with splitter plate

    Directory of Open Access Journals (Sweden)

    Ozkan Gokturk Memduh

    2017-01-01

    Full Text Available In the present study, the flow control with a splitter plate was studied considering the annular region of a shrouded cylinder. The effect of splitter plate angle, α which was defined according to the cylinder centreline is investigated experimentally in deep water using Particle image Velocimetry (PIV technique and flow visualization by dye injection method. The range of splitter plate angle was selected within 60°≤ α ≤180° with an increment of 30°. The porosity of the shroud which is a perforated cylinder was selected as β=0.7 in order to have larger fluid entrainment through the cylinder. The results were compared with the no-plate case and showed that the splitter plate located in the annular region of shrouded cylinders is effective on reducing the turbulence levels just behind the cylinder base, as well as the near wake of the perforated shroud.

  2. Control of the flow in the annular region of a shrouded cylinder with splitter plate

    Science.gov (United States)

    Ozkan, Gokturk Memduh; Durhasan, Tahir; Pinar, Engin; Yenicun, Arda; Akilli, Huseyin; Sahin, Besir

    In the present study, the flow control with a splitter plate was studied considering the annular region of a shrouded cylinder. The effect of splitter plate angle, α which was defined according to the cylinder centreline is investigated experimentally in deep water using Particle image Velocimetry (PIV) technique and flow visualization by dye injection method. The range of splitter plate angle was selected within 60°≤ α ≤180° with an increment of 30°. The porosity of the shroud which is a perforated cylinder was selected as β=0.7 in order to have larger fluid entrainment through the cylinder. The results were compared with the no-plate case and showed that the splitter plate located in the annular region of shrouded cylinders is effective on reducing the turbulence levels just behind the cylinder base, as well as the near wake of the perforated shroud.

  3. Numerical study on turbulent flow inside a channel with an extended chamber

    International Nuclear Information System (INIS)

    Lee, Young Tae; Lim, Hee Chang

    2009-01-01

    The paper presents a LES numerical simulation of turbulent flow around an extended chamber. The simulations are carried out on a series of 3-dimensional cavities placed in a turbulent boundary layer at a Reynolds number of 1.0x10 5 based on U and h, which are the velocity at the upper top of the cavity and the depth height, respectively. In order to get an appropriate solution in the Filtered Navier-Stokes equation for the incompressible flow, the computational mesh is densely attracted to the cavity surface and coarsely far-field, as this aids saving the computation cost and rapid convergence. The Boussinesq hypothesis is employed in the subgrid-scale turbulence model. In order to obtain the subgrid-scale turbulent viscosity, the Smagorinsky-Lilly SGS model is applied and the CFL number for time marching is 1.0. The results include the flow variations inside a cavity with the different sizes and shapes.

  4. Uncertainty in counting ice nucleating particles with continuous flow diffusion chambers

    Science.gov (United States)

    Garimella, Sarvesh; Rothenberg, Daniel A.; Wolf, Martin J.; David, Robert O.; Kanji, Zamin A.; Wang, Chien; Rösch, Michael; Cziczo, Daniel J.

    2017-09-01

    This study investigates the measurement of ice nucleating particle (INP) concentrations and sizing of crystals using continuous flow diffusion chambers (CFDCs). CFDCs have been deployed for decades to measure the formation of INPs under controlled humidity and temperature conditions in laboratory studies and by ambient aerosol populations. These measurements have, in turn, been used to construct parameterizations for use in models by relating the formation of ice crystals to state variables such as temperature and humidity as well as aerosol particle properties such as composition and number. We show here that assumptions of ideal instrument behavior are not supported by measurements made with a commercially available CFDC, the SPectrometer for Ice Nucleation (SPIN), and the instrument on which it is based, the Zurich Ice Nucleation Chamber (ZINC). Non-ideal instrument behavior, which is likely inherent to varying degrees in all CFDCs, is caused by exposure of particles to different humidities and/or temperatures than predicated from instrument theory of operation. This can result in a systematic, and variable, underestimation of reported INP concentrations. We find here variable correction factors from 1.5 to 9.5, consistent with previous literature values. We use a machine learning approach to show that non-ideality is most likely due to small-scale flow features where the aerosols are combined with sheath flows. Machine learning is also used to minimize the uncertainty in measured INP concentrations. We suggest that detailed measurement, on an instrument-by-instrument basis, be performed to characterize this uncertainty.

  5. The three-dimensional flow in the chamber of a gas centrifuge with an installed obstacle

    International Nuclear Information System (INIS)

    Elsholz, E.

    1977-01-01

    The flow-field in a very fast rotating chamber under the presence of a stationarily installed obstacle is calculated numerically from the complete set of Navier-Stokes-equations. A special differential approximation applied, provides stable and non-oscillating solutions even within the region of very small Ekman-numbers. This type of approximation will be derived and its advantages are discussed. Finally, a numerical result is presented which includes strong radial density gradients and shows very clearly the compressible effects as well as the mechanism of vortex shedding generated by the obstacle. (orig.) [de

  6. Laminar dispersion in parallel plate sections of flowing systems used in analytical chemistry and chemical engineering

    NARCIS (Netherlands)

    Kolev, S.D.; Kolev, Spas D.; van der Linden, W.E.

    1991-01-01

    An exact solution of the convective-diffusion equation for fully developed parallel plate laminar flow was obtained. It allows the derivation of theoretical relationships for calculating the Peclet number in the axially dispersed plug flow model and the concentration distribution perpendicular to

  7. MHD flow of a dusty viscoelastic liquid through a porous medium between two inclined parallel plates

    International Nuclear Information System (INIS)

    Singh, A.K.; Singh, N.P.

    1996-01-01

    Magnetohydrodynamic flow of a dusty viscoelastic liquid (Oldroyd B-liquid) through a porous medium between two parallel plates inclined to the horizon has been studied. The liquid velocity, dust particle velocity and flux of flow have been obtained. Earlier results have been deduced as particular cases of the present investigation. The physical situation of the motion has been discussed graphically. (author)

  8. Wave propagation and power flow in an acoustic metamaterial plate with lateral local resonance attachment

    Science.gov (United States)

    Wang, Ting; Sheng, Meiping; Ding, Xiaodong; Yan, Xiaowei

    2018-03-01

    This paper presents analysis on wave propagation and power flow in an acoustic metamaterial plate with lateral local resonance. The metamaterial is designed to have lateral local resonance systems attached to a homogeneous plate. Relevant theoretical analysis, numerical modelling and application prospect are presented. Results show that the metamaterial has two complete band gaps for flexural wave absorption and vibration attenuation. Damping can smooth and lower the metamaterial’s frequency responses in high frequency ranges at the expense of the band gap effect, and as an important factor to calculate the power flow is thoroughly investigated. Moreover, the effective mass density becomes negative and unbounded at specific frequencies. Simultaneously, power flow within band gaps are dramatically blocked from the power flow contour and power flow maps. Results from finite element modelling and power flow analysis reveal the working mechanism of the flexural wave attenuation and power flow blocked within the band gaps, where part of the flexural vibration is absorbed by the vertical resonator and the rest is transformed through four-link-mechanisms to the lateral resonators that oscillate and generate inertial forces indirectly to counterbalance the shear forces induced by the vibrational plate. The power flow is stored in the vertical and lateral local resonance, as well as in the connected plate.

  9. On the prediction of condenser plate temperatures in a cross-flow condenser

    NARCIS (Netherlands)

    Ganzevles, F.L.A.; Geld, van der C.W.M.

    2002-01-01

    A prediction method is presented for the gas-sided plate temperatures at the inlet and at the outlet of a compact, cross-flow condenser. The method employs measured (or predicted) heat flow rates and temperatures of both coolant and gas, at inlet and outlet. The method is validated using infrared

  10. Measurement of air kerma rates for 6- to 7-MeV high-energy gamma-ray field by ionisation chamber and build-up plate.

    Science.gov (United States)

    Kowatari, Munehiko; Tanimura, Yoshihiko; Tsutsumi, Masahiro

    2014-12-01

    The 6- to 7-MeV high-energy gamma-ray calibration field by the (19)F(p, αγ)(16)O reaction is to be served at the Japan Atomic Energy Agency. For the determination of air kerma rates using an ionisation chamber in the 6- to 7-MeV high-energy gamma-ray field, the establishment of the charged particle equilibrium must be achieved during measurement. In addition to measurement of air kerma rates by the ionisation chamber with a thick build-up cap, measurement using the ionisation chamber and a build-up plate (BUP) was attempted, in order to directly determine air kerma rates under the condition of regular calibration for ordinary survey meters and personal dosemeters. Before measurements, Monte Carlo calculations were made to find the optimum arrangement of BUP in front of the ionisation chamber so that the charged particle equilibrium could be well established. Measured results imply that air kerma rates for the 6- to 7-MeV high-energy gamma-ray field could be directly determined under the appropriate condition using an ionisation chamber coupled with build-up materials. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Flow channel shape optimum design for hydroformed metal bipolar plate in PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Linfa; Lai, Xinmin; Liu, Dong' an; Hu, Peng [State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240 (China); Ni, Jun [Department of Mechanical Engineering and Applied Mechanics, University of Michigan, Ann Arbor, MI 48109 (United States)

    2008-03-15

    Bipolar plate is one of the most important and costliest components of polymer electrolyte membrane (PEM) fuel cells. Micro-hydroforming is a promising process to reduce the manufacturing cost of PEM fuel cell bipolar plates made of metal sheets. As for hydroformed bipolar plates, the main defect is the rupture because of the thinning of metal sheet during the forming process. The flow channel section decides whether high quality hydroformed bipolar plates can be successively achieved or not. Meanwhile, it is also the key factor that is related with the reaction efficiency of the fuel cell stacks. In order to obtain the optimum flow channel section design prior the experimental campaign, some key geometric dimensions (channel depth, channel width, rib width and transition radius) of flow channel section, which are related with both reaction efficiency and formability, are extracted and parameterized as the design variables. By design of experiments (DOE) methods and an adoptive simulated annealing (ASA) optimization method, an optimization model of flow channel section design for hydroformed metal bipolar plate is proposed. Optimization results show that the optimum dimension values for channel depth, channel width, rib width and transition radius are 0.5, 1.0, 1. 6 and 0.5 mm, respectively with the highest reaction efficiency (79%) and the acceptable formability (1.0). Consequently, their use would lead to improved fuel cell efficiency for low cost hydroformed metal bipolar plates. (author)

  12. Experimental determination of a flow model in a plate exchanger

    International Nuclear Information System (INIS)

    Fontaine, J.; Lannoy, F.

    1975-01-01

    Starting from the conductivimetric measurement of the response of a plate exchanger to a stepped input signal, two techniques (i.e. one direct and one indirect) for the determination of the coefficients of the mathematical model describing the behaviour of the exchanger are compared. The results show that these coefficients can be obtained with a sufficient accuracy by the direct reading of two parameters of the response curve. Variation of these coefficients with rated conditions show, moreover that the phenomenon is not linear and that these coefficients must be considered as variable parameters [fr

  13. Modification of Aortic Cannula With an Inlet Chamber to Induce Spiral Flow and Improve Outlet Flow.

    Science.gov (United States)

    Darlis, Nofrizalidris; Osman, Kahar; Padzillah, Muhamad Hasbullah; Dillon, Jeswant; Md Khudzari, Ahmad Zahran

    2018-05-01

    Physiologically, blood ejected from the left ventricle in systole exhibited spiral flow characteristics. This spiral flow has been proven to have several advantages such as lateral reduction of directed forces and thrombus formation, while it also appears to be clinically beneficial in suppressing neurological complications. In order to deliver spiral flow characteristics during cardiopulmonary bypass operation, several modifications have been made on an aortic cannula either at the internal or at the outflow tip; these modifications have proven to yield better hemodynamic performances compared to standard cannula. However, there is no modification done at the inlet part of the aortic cannula for inducing spiral flow so far. This study was carried out by attaching a spiral inducer at the inlet of an aortic cannula. Then, the hemodynamic performances of the new cannula were compared with the standard straight tip end-hole cannula. This is achieved by modeling the cannula and attaching the cannula at a patient-specific aorta model. Numerical approach was utilized to evaluate the hemodynamic performance, and a water jet impact experiment was used to demonstrate the jet force generated by the cannula. The new spiral flow aortic cannula has shown some improvements by reducing approximately 21% of impinging velocity near to the aortic wall, and more than 58% reduction on total force generated as compared to standard cannula. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  14. Numerical Study on the Effect of Distribution Plates in the Manifolds on the Flow Distribution and Thermal Performance of a Flat Plate Solar Collector

    Directory of Open Access Journals (Sweden)

    Juan Manuel García-Guendulain

    2018-04-01

    Full Text Available Flow maldistribution represents a problem of particular interest in the engineering field for several thermal systems. In flat plate solar collectors, the thermal efficiency strongly depends on the flow distribution through the riser tubes, where a uniform distribution causes a uniform temperature distribution and therefore a higher efficiency. In this work, a Computational Fluid Dynamics (CFD numerical analysis has been carried out using the commercial software FLUENT®, in order to determine the flow distribution, pressure drop and hence the thermal efficiency of a solar collector with distribution flow plates inside the manifolds. The obtained numerical solution for this type of thermal systems has been validated with experimental results available in literature for laminar and turbulent flow. Four distribution plate configurations were analyzed. Results show that using two distribution plates in each of both manifolds improves the flow uniformity up to 40% under the same operating conditions when distribution plates are not used. Besides, it is shown that there exists an increase in the overall pressure drop which is practically negligible for the tilt angles commonly employed in the installation of flat plate solar collectors in Mexico. The use of closed end distribution plates on the dividing and combining manifolds allows the thermal efficiency to become close to the ideal thermal efficiency which is obtained with a uniform flow distribution.

  15. Transient convective heat transfer to laminar flow from a flat plate with constant heat capacity

    International Nuclear Information System (INIS)

    Hanawa, Juichi

    1980-01-01

    Most basic transient heat transfer problem is the transient response characteristics of forced convection heat transfer in the flow along a flat plate or in a tube. In case of the laminar flow along a flat plate, the profile method using steady temperature distribution has been mostly adopted, but its propriety has not been clarified yet. About the unsteady heat transfer in the laminar flow along a flat plate, the analysis or experiment evaluating the heat capacity of the flat plate exactly was never carried out. The purpose of this study is to determine by numerical calculation the unsteady characteristics of the boundary layer in laminar flow and to confirm them by experiment concerning the unsteady heat transfer when a flat plate with a certain heat capacity is placed in parallel in uniform flow and given a certain quantity of heat generation suddenly. The basic equation and the solution are given, and the method of numerical calculation and the result are explained. The experimental setup and method, and the experimental results are shown. Both results were in good agreement, and the response of wall temperature, the response of Nusselt number and the change of temperature distribution in course of time were able to be determined by applying Laplace transformation and numerical Laplace inverse transformation to the equation. (Kako, I.)

  16. Stratified steady and unsteady two-phase flows between two parallel plates

    International Nuclear Information System (INIS)

    Sim, Woo Gun

    2006-01-01

    To understand fluid dynamic forces acting on a structure subjected to two-phase flow, it is essential to get detailed information about the characteristics of two-phase flow. Stratified steady and unsteady two-phase flows between two parallel plates have been studied to investigate the general characteristics of the flow related to flow-induced vibration. Based on the spectral collocation method, a numerical approach has been developed for the unsteady two-phase flow. The method is validated by comparing numerical result to analytical one given for a simple harmonic two-phase flow. The flow parameters for the steady two-phase flow, such as void fraction and two-phase frictional multiplier, are evaluated. The dynamic characteristics of the unsteady two-phase flow, including the void fraction effect on the complex unsteady pressure, are illustrated

  17. 3D CFD fluid flow and thermal analyses of a new design of plate heat exchanger

    Directory of Open Access Journals (Sweden)

    Pianko-Oprych Paulina

    2017-03-01

    Full Text Available The paper presents a Computational Fluid Dynamics (CFD numerical study for a new design of a plate heat exchanger with two different flow patterns. The impact of geometric characteristics of the two studied geometries of exchanger plates on the intensification process of heat transfer was considered. The velocity, temperature and pressure distributions along the heat exchanger were examined. The CFD results were validated against experimental data and a good agreement was achieved. The results revealed that geometrical arrangement of the plates strongly influence the fluid flow. An increase in the Reynolds number led to lowering the friction factor value and increasing the pressure drop. The configuration II of the plate heat exchanger resulted in lower outlet hot fluid temperature in comparison with the configuration I, which means improvement of heat transfer.

  18. Fluorescent multiplex cell flow systems and methods

    KAUST Repository

    Merzaban, Jasmeen

    2017-06-01

    Systems and methods are provided for simultaneously assaying cell adhesion or cell rolling for multiple cell specimens. One embodiment provides a system for assaying adhesion or cell rolling of multiple cell specimens that includes a confocal imaging system containing a parallel plate flow chamber, a pump in fluid communication with the parallel plate flow chamber via a flow chamber inlet line and a cell suspension in fluid communication with the parallel plate flow chamber via a flow chamber outlet line. The system also includes a laser scanning system in electronic communication with the confocal imaging system, and a computer in communication with the confocal imaging system and laser scanning system. In certain embodiments, the laser scanning system emits multiple electromagnetic wavelengths simultaneously it cause multiple fluorescent labels having different excitation wavelength maximums to fluoresce. The system can simultaneously capture real-time fluorescence images from at least seven cell specimens in the parallel plate flow chamber.

  19. Heat transfer effects on flow past an exponentially accelerated vertical plate with variable temperature

    Directory of Open Access Journals (Sweden)

    Muthucumaraswamy R.

    2008-01-01

    Full Text Available An exact solution to the problem of flow past an exponentially accelerated infinite vertical plate with variable temperature is analyzed. The temperature of the plate is raised linearly with time t. The dimensionless governing equations are solved using Laplace-transform technique. The velocity and temperature profiles are studied for different physical parameters like thermal Grashof number Gr, time and an accelerating parameter a. It is observed that the velocity increases with increasing values of a or Gr.

  20. Radiation Effects on the Flow and Heat Transfer over a Moving Plate in a Parallel Stream

    International Nuclear Information System (INIS)

    Ishak, Anuar

    2009-01-01

    Effects of thermal radiation on the steady laminar boundary layer flow over a moving plate in a moving fluid is investigated. Under certain conditions, the present problem reduces to the classical Blasius and Sakiadis problems. It is found that dual solutions exist when the plate and the fluid move in the opposite directions. Moreover, the existence of thermal radiation is to reduce the heat transfer rate at the surface. (fundamental areas of phenomenology (including applications))

  1. Investigation of the applicability of a special parallel-plate ionization chamber for x-ray beam dosimetry

    International Nuclear Information System (INIS)

    Perini, Ana P.; Neves, Lucio P.; Caldas, Linda V.E.

    2014-01-01

    Diagnostic x-rays are the greatest source of exposition to ionizing radiation of the population worldwide. In order to obtain accurate and lower-cost dosimeters for quality control assurance of medical x-ray facilities, a special ionization chamber was designed at the Calibration Laboratory of the IPEN, for dosimetry in diagnostic radiology beams. For the chamber characterization some tests were undertaken. Monte Carlo simulations were proposed to evaluate the distribution of the deposited energy in the sensitive volume of the ionization chamber and the collecting electrode effect on the chamber response. According to the obtained results, this special ionization chamber presents potential use for dosimetry of conventional diagnostic radiology beams. - Highlights: • An ionization chamber with a novel design was characterized for x-ray beam dosimetry. • This ionization chamber was evaluated in diagnostic radiology qualities. • The characterization tests results were within the recommended limits. • Monte Carlo simulations were employed to evaluate the design of the dosimeter. • The developed prototype is a good alternative for calibration laboratories and clinics

  2. Study of flow past an exponentially accelerated isothermal vertical plate in the presence of chemical reaction

    Directory of Open Access Journals (Sweden)

    Muthucumaraswamy R.

    2010-01-01

    Full Text Available Theoretical study of unsteady flow past an exponentially accelerated infinite isothermal vertical plate with variable mass diffusion has been presented in the presence of homogeneous chemical reaction of first order. The plate temperature is raised to Tw and species concentration level near the plate is made to rise linearly with time. The dimensionless governing equations are solved using Laplace-transform technique. The velocity profiles are studied for different physical parameters like chemical reaction parameter, thermal Grashof number, mass Grashof number, a and time. It is observed that the velocity increases with increasing values of a or t. But the trend is just reversed with respect to K.

  3. Some studies on the pulse-height loss due to capacitive decay in the detector-circuit of parallel plate ionization chambers

    International Nuclear Information System (INIS)

    Sharma, S.L.; Anil Kumar, G.; Choudhury, R.K.

    2006-01-01

    Pulse-type ionization chambers are invariably operated in the electron-sensitive mode where the capacitive decay in the detector-circuit during the electron collection produces loss in the pulse-height. In order to understand and appreciate the effect of this capacitive decay on the detector response, we have carried out Monte Carlo simulations of the response of two-electrode parallel plate ionization chambers with and without the capacitive decay keeping shaping time so large that the ballistic deficit is negligibly small. These simulations have been carried out incorporating the physical processes, namely, emission of charged particles from a point radioactive source, the generation of charge carriers in the active volume, separation and acceleration of the charge carriers, transport of the charge carriers, induction of charges on the electrodes, pulse processing by preamplifier-amplifier network, etc. These simulations have shown that the concerned capacitive decay produces appreciable loss in the pulse-height, if the detector-circuit time constant is of the order of maximum electron collection time. We have also carried out measurements on the pulse-height loss due to the capacitive decay in the detector-circuit during the electron collection for a two-electrode parallel plate ionization chamber. The experimental data on the pulse-height loss match reasonably well with the theoretical predictions

  4. Uncertainty in counting ice nucleating particles with continuous flow diffusion chambers

    Directory of Open Access Journals (Sweden)

    S. Garimella

    2017-09-01

    Full Text Available This study investigates the measurement of ice nucleating particle (INP concentrations and sizing of crystals using continuous flow diffusion chambers (CFDCs. CFDCs have been deployed for decades to measure the formation of INPs under controlled humidity and temperature conditions in laboratory studies and by ambient aerosol populations. These measurements have, in turn, been used to construct parameterizations for use in models by relating the formation of ice crystals to state variables such as temperature and humidity as well as aerosol particle properties such as composition and number. We show here that assumptions of ideal instrument behavior are not supported by measurements made with a commercially available CFDC, the SPectrometer for Ice Nucleation (SPIN, and the instrument on which it is based, the Zurich Ice Nucleation Chamber (ZINC. Non-ideal instrument behavior, which is likely inherent to varying degrees in all CFDCs, is caused by exposure of particles to different humidities and/or temperatures than predicated from instrument theory of operation. This can result in a systematic, and variable, underestimation of reported INP concentrations. We find here variable correction factors from 1.5 to 9.5, consistent with previous literature values. We use a machine learning approach to show that non-ideality is most likely due to small-scale flow features where the aerosols are combined with sheath flows. Machine learning is also used to minimize the uncertainty in measured INP concentrations. We suggest that detailed measurement, on an instrument-by-instrument basis, be performed to characterize this uncertainty.

  5. Parametric Study of Cantilever Plates Exposed to Supersonic and Hypersonic Flows

    Science.gov (United States)

    Sri Harsha, A.; Rizwan, M.; Kuldeep, S.; Giridhara Prasad, A.; Akhil, J.; Nagaraja, S. R.

    2017-08-01

    Analysis of hypersonic flows associated with re-entry vehicles has gained a lot of significance due to the advancements in Aerospace Engineering. An area that is studied extensively by researchers is the simultaneous reduction aerodynamic drag and aero heating in re-entry vehicles. Out of the many strategies being studied, the use of aerospikes at the stagnation point of the vehicle is found to give favourable results. The structural stability of the aerospike becomes important as it is exposed to very high pressures and temperatures. Keeping this in view, the deflection and vibration of an inclined cantilever plate in hypersonic flow is carried out using ANSYS. Steady state pressure distribution obtained from Fluent is applied as load to the transient structural module for analysis. After due validation of the methods, the effects of parameters like flow Mach number, plate inclination and plate thickness on the deflection and vibration are studied.

  6. Numerical Study of the Inertia Effect on Flow Distribution in Micro-gap Plate Heat Exchanger

    International Nuclear Information System (INIS)

    Park, Jang Min; Yoon, Seok Ho; Lee, Kong Hoon; Song Chan Ho

    2014-01-01

    This paper presents numerical study on flow and heat transfer characteristics in micro-gap plate heat exchanger. In particular, we investigate the effect of flow inertia on the flow distribution from single main channel to multiple parallel micro-gaps. The flow regime of the main channel is varied from laminar regime (Reynolds number of 100) to turbulent regime (Reynolds number of 10000) by changing the flow rate, and non-uniformity of the flow distribution and temperature field is evaluated quantitatively based on the standard deviation. The flow distribution is found to be significantly affected by not only the header design but also the flow rate of the main channel. It is also observed that the non-uniformity of the temperature field has its maximum at the intermediate flow regime

  7. Plate heat exchanger - inertia flywheel performance in loss of flow transient

    International Nuclear Information System (INIS)

    Abou-El-Maaty, Talal; Abd-El-Hady, Amr

    2009-01-01

    One of the most versatile types of heat exchangers used is the plate heat exchanger. It has principal advantages over other heat exchangers in that plates can be added and/or removed easily in order to change the area available for heat transfer and therefore its overall performance. The cooling systems of Egypt's second research reactor (ETRR 2) use this type of heat exchanger for cooling purposes in its primary core cooling and pool cooling systems. In addition to the change in the number of heat exchanger cooling channels, the effect of changing the amount of mass flow rate on the heat exchanger performance is an important issues in this study. The inertia flywheel mounted on the primary core cooling system pump with the plate heat exchanger plays an important role in the case of loss of flow transients. The PARET code is used to simulate the effect of loss of flow transients on the reactor core. Hence, the core outlet temperature with the pump-flywheel flow coast down is fed into the plate heat exchanger model developed to estimate the total energy transferred to the cooling tower, the primary side heat exchanger temperature variation, the transmitted heat exchanger power, and the heat exchanger effectiveness. In addition, the pressure drop in both, the primary side and secondary side of the plate heat exchanger is calculated in all simulated transients because their values have limits beyond which the heat exchanger is useless. (orig.)

  8. A numerical investigation of turbulent flow in an 18-plate nuclear fuel assembly

    International Nuclear Information System (INIS)

    Yu, R.; Lightstone, M.F.

    2003-01-01

    A numerical simulation of the fluid flow in the core of the McMaster Nuclear Reactor (MNR) was performed. The standard k - ε turbulence model together with a two-layer wall boundary model was used in the current study. A two-dimensional numerical model for the MNR 18-plate nuclear fuel assembly was developed using the advanced commercial computational fluid dynamics (CFD) code CFX-TASCflow. The numerical predictions were compared with experimental data for the MNR 18-plate assembly at the same flow conditions. In general, the code over predicts the pressure drop for the range of the mass flow rate investigated, however, the difference decreases as the mass flow rate (or Reynolds number) increases. Errors of less than 4% were obtained for mass flows greater than 4.0 kg/s. The comparison shows that the predicted flow distribution and velocities are very close to the measured data for the high Reynolds number flows. It is found that the k - ε model with the two-layer wall boundary model can predict the flow in the vertical parallel plate channels in the low Reynolds number region (Re=3000 to 10,000) very well. (author)

  9. Visual Inspection of the Flow Distribution Plate Bolts of a Nuclear Steam Generator

    International Nuclear Information System (INIS)

    Jeong, Woo Tae; Kim, Suk Tae; Sohn, Wook; Kang, Duk Won; Kang, Seok Chul

    2007-01-01

    To develop a system for visually inspecting the flow distribution plate (FDP) bolts of a nuclear steam generator, we reviewed several types of similar inspection equipment. The equipment which are currently available are mostly for inspecting lower part of a steam generator such as tube sheets and annulus except ELVS (Eggcrate Visual Inspection System). However, the design concept of ELVS could not be used for developing a device which enables the visual inspection of flow distribution plate bolts. Therefore, based on the current state of the art technology on the similar equipment, we conceptually designed a new inspection system for checking the FDP bolts

  10. Validation of the flow-through chamber (FTC and steady-state (SS methods for clearance rate measurements in bivalves

    Directory of Open Access Journals (Sweden)

    Poul S. Larsen

    2011-09-01

    To obtain precise and reliable laboratory clearance rate (filtration rate measurements with the ‘flow-through chamber method’ (FTC the design must ensure that only inflow water reaches the bivalve's inhalant aperture and that exit flow is fully mixed. As earlier recommended these prerequisites can be checked by a plot of clearance rate (CR versus increasing through-flow (Fl to reach a plateau, which is the true CR, but we also recommend to plot percent particles cleared versus reciprocal through-flow where the plateau becomes the straight line CR/Fl, and we emphasize that the percent of particles cleared is in itself neither a criterion for valid CR measurement, nor an indicator of appropriate ‘chamber geometry’ as hitherto adapted in many studies. For the ‘steady-state method’ (SS, the design must ensure that inflow water becomes fully mixed with the bivalve's excurrent flow to establish a uniform chamber concentration prevailing at its incurrent flow and at the chamber outlet. These prerequisites can be checked by a plot of CR versus increasing Fl, which should give the true CR at all through-flows. Theoretically, the experimental uncertainty of CR for a given accuracy of concentration measurements depends on the percent reduction in particle concentration (100×P from inlet to outlet of the ideal ‘chamber geomety’. For FTC, it decreases with increasing values of P while for SS it first decreases but then increases again, suggesting the use of an intermediate value of P. In practice, the optimal value of P may depend on the given ‘chamber geometry’. The fundamental differences between the FTC and the SS methods and practical guidelines for their use are pointed out, and new data on CR for the blue mussel, Mytilus edulis, illustrate a design and use of the SS method which may be employed in e.g. long-term growth experiments at constant algal concentrations.

  11. A comparative study of the effects of cone-plate and parallel-plate geometries on rheological properties under oscillatory shear flow

    CSIR Research Space (South Africa)

    Yong Song, H

    2017-11-01

    Full Text Available -1 Korea-Australia Rheology Journal A comparative study of the effects of cone-plate and parallel- plate geometries on rheological properties under oscillatory shear flow Hyeong Yong Song1, Reza Salehiyan2, Xiaolei Li1, Seung Hak Lee1 and Kyu Hyun1...

  12. Internal (Annular) and Compressible External (Flat Plate) Turbulent Flow Heat Transfer Correlations.

    Energy Technology Data Exchange (ETDEWEB)

    Dechant, Lawrence [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Smith, Justin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-01

    Here we provide a discussion regarding the applicability of a family of traditional heat transfer correlation based models for several (unit level) heat transfer problems associated with flight heat transfer estimates and internal flow heat transfer associated with an experimental simulation design (Dobranich 2014). Variability between semi-empirical free-flight models suggests relative differences for heat transfer coefficients on the order of 10%, while the internal annular flow behavior is larger with differences on the order of 20%. We emphasize that these expressions are strictly valid only for the geometries they have been derived for e.g. the fully developed annular flow or simple external flow problems. Though, the application of flat plate skin friction estimate to cylindrical bodies is a traditional procedure to estimate skin friction and heat transfer, an over-prediction bias is often observed using these approximations for missile type bodies. As a correction for this over-estimate trend, we discuss a simple scaling reduction factor for flat plate turbulent skin friction and heat transfer solutions (correlations) applied to blunt bodies of revolution at zero angle of attack. The method estimates the ratio between axisymmetric and 2-d stagnation point heat transfer skin friction and Stanton number solution expressions for sub-turbulent Reynolds numbers %3C1x10 4 . This factor is assumed to also directly influence the flat plate results applied to the cylindrical portion of the flow and the flat plate correlations are modified by

  13. Numerical investigation of the flow inside the combustion chamber of a plant oil stove

    Science.gov (United States)

    Pritz, B.; Werler, M.; Wirbser, H.; Gabi, M.

    2013-10-01

    Recently a low cost cooking device for developing and emerging countries was developed at KIT in cooperation with the company Bosch und Siemens Hausgeräte GmbH. After constructing an innovative basic design further development was required. Numerical investigations were conducted in order to investigate the flow inside the combustion chamber of the stove under variation of different geometrical parameters. Beyond the performance improvement a further reason of the investigations was to rate the effects of manufacturing tolerance problems. In this paper the numerical investigation of a plant oil stove by means of RANS simulation will be presented. In order to reduce the computational costs different model reduction steps were necessary. The simulation results of the basic configuration compare very well with experimental measurements and problematic behaviors of the actual stove design could be explained by the investigation.

  14. Flow structure of conical distributed multiple gas jets injected into a water chamber

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jiajun; Yu, Yonggang [Nanjing University of Science and Technology, Nanjing (China)

    2017-04-15

    Based on an underwater gun firing project, a mock bullet with several holes on the head was designed and experimented to observe the combustion gas injected into a cylindrical water chamber through this mock bullet. The combustion gas jets contain one vertical central jet and 4 to 8 slant lateral jets. A high speed camera system was used to record the expansion of gas jets in the experimental study. In numerical simulations, the Euler two-fluid model and volume of fluid method were adopted to describe the gas-liquid flow. The results show the backflow zone in lateral jet is the main factor influencing the gas-liquid turbulent mixing in downstream. On cross sections, the gas volume fraction increased with time but the growth rate decreased. With a change of nozzle structure, the gas fraction was more affected than the shock structure.

  15. Granular flow considerations in the design of a cascade solid breeder reaction chamber

    International Nuclear Information System (INIS)

    Walton, O.R.

    1983-10-01

    Both horizontally and vertically oriented rotating chambers with granular material held on the inner surface by centrifugal action are examined. Modifications to the condition for controlled quasi-static flow on an incline plane, phi/sub w/ 0 +- 10 0 for ceramic particles and metal surfaces. For vertical orientations the maximum half-angle of the top cone is slightly less than the wall friction angle phi/sub w/ while the lower portion can have a half angle as large as (90 0 - phi/sub w). Percolation of fines through shearing granular solids is briefly discussed and recommended experimental and calculational studies to obtain a better understanding of this behavior are described

  16. On oscillations of an elastically mounted plate in flow

    Science.gov (United States)

    Selyutskiy, Yury

    2018-05-01

    Study of aerodynamic flutter has a long history. Interest to this problem is stimulated by applications: on the one hand, the flutter effect should be eliminated in order to ensure durability of structures; on the other hand, this phenomenon can be used to harvest energy from the flow. In the present work, an aeroelastic system with two degrees of freedom (translational and rotational) is considered. Aerodynamic load is described using the quasi-steady approach. Dependence of the number of equilibrium positions and their stability on system parameters is discussed. Limit cycles arising in the system are studied numerically.

  17. Experimental Study on EHD Flow Transition in a Small Scale Wire-plate ESP

    Directory of Open Access Journals (Sweden)

    Wang Chuan

    2016-06-01

    Full Text Available The electrohydrodynamic (EHD flow induced by the corona discharge was experimentally investigated in an electrostatic precipitator (ESP. The ESP was a narrow horizontal Plexiglas box (1300 mm×60 mm×60 mm. The electrode set consisted of a single wire discharge electrode and two collecting aluminum plate electrodes. Particle Image Velocimetry (PIV method was used to visualize the EHD flow characteristics inside the ESP seeded with fine oil droplets. The influence of applied voltage (from 8 kV to 10 kV and primary gas flow (0.15 m/s, 0.2 m/s, 0.4 m/s on the EHD flow transition was elucidated through experimental analysis. The formation and transition of typical EHD flows from onset to the fully developed were described and explained. Experimental results showed that the EHD flow patterns change depends on the gas velocity and applied voltage. EHD flow starts with flow streamlines near collecting plates bending towards the wire electrode, forming two void regions. An oscillating jet forming the downstream appeared and moved towards the wire electrode as voltage increased. For higher velocities (≥0.2 m/s, the EHD transition became near wire phenomenon with a jet-like flow structure near the wire, forming a void region behind the wire and expanding as voltage increased. Fully developed EHD secondary flow in the form of counter-rotating vortices appeared upstream with high applied voltage.

  18. Magnetohydrodynamic unsteady flow of a Maxwell fluid past a flat plate

    International Nuclear Information System (INIS)

    Khandpur, S.L.; Ravi Kant

    1979-01-01

    A study of the equations describing the flow pattern set up in a linear electrically conducting viscoelastic fluid past an infinite flat plate in the presence of a transverse magnetic field has been made, when the plate is moving parallel to itself with an arbitrary time dependent velocity. The pressure is assumed to be uniform with initial velocity distribution in an exponential form. Operational methods are used to obtain the exact solutions for the velocity profiles. The effects of relaxation parameter of the fluid and magnetic field have been studied. Several particular cases are easily deduced of which two cases: (i) when the plate is moving in its own plane harmonically with time, and (ii) when the velocity of the plate is decaying exponentially with time, are discussed. (auth.)

  19. Numerical calculation of velocity distribution near a vertical flat plate immersed in bubble flow

    International Nuclear Information System (INIS)

    Matsuura, Akihiro; Nakamura, Hajime; Horihata, Hideyuki; Hiraoka, Setsuro; Aragaki, Tsutomu; Yamada, Ikuho; Isoda, Shinji.

    1992-01-01

    Liquid and gas velocity distributions for bubble flow near a vertical flat plate were calculated numerically by using the SIMPLER method, where the flow was assumed to be laminar, two-dimensional, and at steady state. The two-fluid flow model was used in the numerical analysis. To calculate the drag force on a small bubble, Stokes' law for a rigid sphere is applicable. The dimensionless velocity distributions which were arranged with characteristic boundary layer thickness and maximum liquid velocity were adjusted with a single line and their forms were similar to that for single-phase wall-jet flow. The average wall shear stress derived from the velocity gradient at the plate wall was strongly affected by bubble diameter but not by inlet liquid velocity. The present dimensionless velocity distributions obtained numerically agreed well with previous experimental results, and the proposed numerical algorithm was validated. (author)

  20. Effect of magnetic field on Blasius and Sakiadis flow of nanofluids past an inclined plate

    Directory of Open Access Journals (Sweden)

    S.P. Anjali Devi

    2017-11-01

    Full Text Available A theoretical study on the effect of magnetic field on the classical Blasius and Sakiadis flow of nanofluids over an inclined plate is presented in this paper. The governing partial differential equations are converted into ordinary differential equations using suitable similarity transformations. The transformed boundary layer equations are solved numerically using MATLAB (bvp4c. Two types of nanoparticles are chosen namely copper and alumina in the base fluid of water with the Prandtl number (Pr = 6.2. The effects of the governing physical parameters over the velocity, temperature, skin friction coefficient and reduced Nusselt number for both the Blasius and Sakiadis flows are displayed graphically. The characteristics of physical and engineering interest are discussed in detail. Keywords: Nanofluid, Blasius flow, Sakiadis flow, MHD, Inclined plate, Mixed convection

  1. Prandtl boundary layer expansions of steady Navier-Stokes flows over a moving plate

    OpenAIRE

    Guo, Yan; Nguyen, Toan T.

    2014-01-01

    This paper concerns the validity of the Prandtl boundary layer theory in the inviscid limit for steady incompressible Navier-Stokes flows. The stationary flows, with small viscosity, are considered on $[0,L]\\times \\mathbb{R}_{+}$, assuming a no-slip boundary condition over a moving plate at $y=0$. We establish the validity of the Prandtl boundary layer expansion and its error estimates.

  2. Simulation techniques for spatially evolving instabilities in compressible flow over a flat plate

    NARCIS (Netherlands)

    Wasistho, B.; Geurts, Bernardus J.; Kuerten, Johannes G.M.

    1997-01-01

    In this paper we present numerical techniques suitable for a direct numerical simulation in the spatial setting. We demonstrate the application to the simulation of compressible flat plate flow instabilities. We compare second and fourth order accurate spatial discretization schemes in combination

  3. Forced and free convection hydromagnetic flow past a vertical flat plate

    International Nuclear Information System (INIS)

    Abdelkhalek, M.M.

    2004-01-01

    The effects of magnetic field and temperature heat source on the free and forced convection flow past an infinite vertical plate is studied analytically. Solutions of the reduced equation appropriate in the forced convection and free convection regime are obtained using perturbation technique. The expression for the velocity field, skin friction and Nusselt number have been obtained

  4. The flow in an oil/water plate heat exchanger for the automotive industry

    OpenAIRE

    Lozano , A.; Barreras , F.; Fueyo , N.; Santodomingo , S.

    2008-01-01

    The flow in an oil/water plate heat exchanger for the automotive industry correspondence: Corresponding author. Tel.: +34976716463; fax: +34976716456. (Lozano, A.) (Lozano, A.) LITEC/CSIC--> , Mar?'a de Luna 10--> , 50018--> , Zaragoza--> - SPAIN (Lozano, A.) SPAIN (Lozano, A.) LITEC/CSIC--> , Mar?'a de Luna 10--> , 50018--> , Zaragoza--> - S...

  5. Measurement of flow phenomena in the vicinity of a PWR tie plate geometry. Final report

    International Nuclear Information System (INIS)

    Lee, R.S.L.; Srinivasan, J.; Cho, S.K.; Wang, J.L.

    1981-01-01

    The flow of an air-water droplet dispersion in a simulated 3D test section in the reflood portion of LOCA is studied. For this purpose, a new scheme of Laser-Doppler Anemometry for the simultaneous measurement of size and velocity of large-size (0.5mm-6mm) droplets has been developed and utilized. In terms of droplet reentrainment from the tie-plate, three flow regimes have been identified, depending on the velocity level of the flow; the dome formation stage, the oscillating dome stage and the wall film breaking up stage. Detailed measurements have been made in these regimes to obtain the local droplet sizes, droplet velocity distribution, air velocity distributions and momentum flux of both incoming and outgoing dispersion through the tie-plate. It has been observed that the size distribution of the reentrained droplets depends mainly on the flow regimes and is essentially independent of that of the incoming dispersion below the tie-plate. These reentrained droplets are found to be mostly in the neighborhood of 1mm in size and their trajectories on leaving the tie-plate essentially oriented close to the vertical direction. Also the momentum flux of outgoing dispersion differs from that of the incoming dispersion. The measuring technique, the experimental set-up, on-line data acquisition system and the results of the measurements are reported

  6. Unsteady free convection MHD flow between two heated vertical parallel conducting plates

    International Nuclear Information System (INIS)

    Sanyal, D.C.; Adhikari, A.

    2006-01-01

    Unsteady free convection flow of a viscous incompressible electrically conducting fluid between two heated conducting vertical parallel plates subjected to a uniform transverse magnetic field is considered. The approximate analytical solutions for velocity, induced field and temperature distribution are obtained for small and large values of magnetic Reynolds number. The problem is also extended to thermometric case. (author)

  7. Effects of Unsteady Flow Past An Infinite Vertical Plate With Variable ...

    African Journals Online (AJOL)

    The effects of unsteady flow past an infinite vertical plate with variable temperature and constant mass flux are investigated. Laplace transform technique is used to obtain velocity and concentration fields. The computation of the results indicates that the velocity profiles increase with increase in Grashof numbers, mass ...

  8. MHD free convection flow past an oscillating plate in the presence of ...

    African Journals Online (AJOL)

    The study of unsteady magnetohydrodynamic heat and mass transfer in MHD flow past an infinite vertical oscillating plate through porous medium, taking account of the presence of free convection and mass transfer. The energy and chemical species equations are solved in closed form by Laplace-transform technique and ...

  9. Three-dimensional fluctuating Couette flow through the porous plates with heat transfer

    Directory of Open Access Journals (Sweden)

    M. Guria

    2006-06-01

    Full Text Available Unsteady Couette flow of a viscous incompressible fluid between two horizontal porous flat plates is considered. The stationary plate is subjected to a periodic suction and the plate in uniform motion is subjected to uniform injection. Approximate solutions have been obtained for the velocity and the temperature fields, skin friction by using perturbation technique. The heat transfer characteristic has also been studied on taking viscous dissipation into account. It is found that the main flow velocity decreases with increase in frequency parameter. On the other hand, the magnitude of the cross-flow velocity increases with increase in frequency parameter. It is seen that the amplitude of the shear stress due to main flow decreases while that due to cross-flow increases with increase in frequency parameter. It is also seen that the tangent of phase shifts both due to the main and cross-flows decrease with increase in frequency parameter. It is observed that the temperature increases with increase in frequency parameter.

  10. Prediction for the flow distribution and the pressure drop of a plate type fuel assembly

    International Nuclear Information System (INIS)

    Park, Jong Hark; Jo, Dea Sung; Chae, Hee Taek; Lee, Byung Chul

    2011-01-01

    A plate type fuel assembly widely used in many research reactors does not allow the coolant to mix with neighboring fuel channels due to the completely separated flow channels. If there is a serious inequality of coolant distribution among channels, it can reduce thermal-hydraulic safety margin, as well as it can cause a deformation of fuel plates by the pressure difference between neighboring channels, thus the flow uniformity in the fuel assembly should be confirmed. When designing a primary cooling system (PCS), the pressure drop through a reactor core is a dominant value to determine the PCS pump size. The major portion of reactor core pressure drop is caused by the fuel assemblies. However it is not easy to get a reasonable estimation of pressure drop due to the geometric complexity of the fuel assembly and the thin gaps between fuel assemblies. The flow rate through the gap is important part to determine the total flow rate of PCS, so it should be estimated as reasonable as possible. It requires complex and difficult jobs to get useful data. In this study CFD analysis to predict the flow distribution and the pressure drop were conducted on the plate type fuel assembly, which results would be used to be preliminary data to determine the PCS flow rate and to improve the design of a fuel assembly

  11. Performance of a Compression-ignition Engine with a Precombustion Chamber Having High-Velocity Air Flow

    Science.gov (United States)

    Spanogle, J A; Moore, C S

    1931-01-01

    Presented here are the results of performance tests made with a single-cylinder, four stroke cycle, compression-ignition engine. These tests were made on a precombustion chamber type of cylinder head designed to have air velocity and tangential air flow in both the chamber and cylinder. The performance was investigated for variable load and engine speed, type of fuel spray, valve opening pressure, injection period and, for the spherical chamber, position of the injection spray relative to the air flow. The pressure variations between the pear-shaped precombustion chamber and the cylinder for motoring and full load conditions were determined with a Farnboro electric indicator. The combustion chamber designs tested gave good mixing of a single compact fuel spray with the air, but did not control the ensuing combustion sufficiently. Relative to each other, the velocity of air flow was too high, the spray dispersion by injection too great, and the metering effect of the cylinder head passage insufficient. The correct relation of these factors is of the utmost importance for engine performance.

  12. Oscillatory flow at the end of parallel-plate stacks: phenomenological and similarity analysis

    International Nuclear Information System (INIS)

    Mao Xiaoan; Jaworski, Artur J

    2010-01-01

    This paper addresses the physics of the oscillatory flow in the vicinity of a series of parallel plates forming geometrically identical channels. This type of flow is particularly relevant to thermoacoustic engines and refrigerators, where a reciprocating flow is responsible for the desirable energy transfer, but it is also of interest to general fluid mechanics of oscillatory flows past bluff bodies. In this paper, the physics of an acoustically induced flow past a series of plates in an isothermal condition is studied in detail using the data provided by PIV imaging. Particular attention is given to the analysis of the wake flow during the ejection part of the flow cycle, where either closed recirculating vortices or alternating vortex shedding can be observed. This is followed by a similarity analysis of the governing Navier-Stokes equations in order to derive the similarity criteria governing the wake flow behaviour. To this end, similarity numbers including two types of Reynolds number, the Keulegan-Carpenter number and a non-dimensional stack configuration parameter, d/h, are considered and their influence on the phenomena are discussed.

  13. Design of creep machine and creep specimen chamber for carrying out creep tests in flowing liquid sodium

    Energy Technology Data Exchange (ETDEWEB)

    Ravi, S., E-mail: sravi@igcar.gov.in; Laha, K.; Sakthy, S.; Mathew, M.D.; Jayakumar, T.

    2014-02-15

    Highlights: • Design of a lever type creep machine for carrying out creep test in flowing sodium. • Leveling of lever during creep was achieved by automated movement of fulcrum. • Design of creep chamber for providing constant sodium flow rate across creep specimen. • Minimum use of bellow in chamber for sodium containment and mechanical isolation. • Mini-lever mechanism to counter balance load reduction on specimen due to bellow stiffness. - Abstract: A creep testing system has been designed, fabricated, installed and validated for carrying out creep tests in flowing liquid sodium. The testing system consists of two sections namely creep testing machine and an environmental chamber. The testing system has the ability of (i) applying tensile load to the test specimen through a lever, (ii) monitoring continuously the creep elongation and (iii) allowing sodium to flow around the creep specimen at constant velocity. The annular space between the creep specimen and the environmental chamber has been suitably designed to maintain constant sodium flow velocity. Primary and secondary bellows are employed in the environmental chamber to (i) mechanically isolate the creep specimen, (ii) prevent the flowing sodium in contact with air and (iii) maintain an argon gas cover to the leaking sodium if any from primary bellow, with a provision to an alarm get activated by a spark plug. The lever-horizontality during creep test has been maintained by automatically lifting up the fulcrum instead of lowering down the pull rod as conventionally used. A mini lever mechanism has been incorporated in the load train to counter balance the load reduction on specimen from the changing stiffness of the bellows. The validation of the testing system has been established by carrying out creep tests on 316L(N) stainless steel at 873 K over a wide stress range and comparing the results with those obtained in air by employing the developed and conventional creep testing machines.

  14. Flow over a traveling wavy foil with a passively flapping flat plate

    Science.gov (United States)

    Liu, Nansheng; Peng, Yan; Liang, Youwen; Lu, Xiyun

    2012-05-01

    Flow over a traveling wavy foil with a passively flapping flat plate has been investigated using a multiblock lattice Boltzmann equation and the immersed boundary method. The foil undergoes prescribed undulations in the lateral direction and the rigid flat plate has passive motion determined by the fluid structure interaction. This simplified model is used to study the effect of the fish caudal fin and its flexibility on the locomotion of swimming animals. The flexibility of the caudal fin is modeled by a torsion spring acting about the pivot at the conjuncture of the wavy foil and the flat plate. The study reveals that the passively oscillating flat plate contributes half of the propulsive force. The flexibility, represented by the nondimensional natural frequency F, plays a very important role in the movement and propulsive force generation of the whole body. When the plate is too flexible, the drag force is observed. As the flat plate becomes more rigid, the propulsive force that is generated when the undulation is confined to last part of the wavy foil becomes larger. The steady movement occurs at F=5. These results are consistent with the observations of some swimming animals in nature.

  15. The influence of flow maldistribution on the performance of inhomogeneous parallel plate heat exhangers

    DEFF Research Database (Denmark)

    Nielsen, Kaspar Kirstein; Engelbrecht, Kurt; Bahl, Christian R.H.

    2013-01-01

    of 50 random stacks having equal average channel thicknesses with 20 channels each are used to provide a statistical base. The standard deviation of the stacks is varied as are the flow rate (Reynolds number) and the thermal conductivity of the solid heat exchanger material. It is found that the heat...... transfer performance of inhomogeneous stacks of parallel plates may be reduced significantly due to the maldistribution of the fluid flow compared to the ideal homogeneous case. The individual channels experience different flow velocities and this further induces an inter-channel thermal cross talk.......The heat transfer performance of inhomogeneous parallel plate heat exchangers in transient operation is investigated using an established model. A performance parameter, denoted the Nusselt-scaling factor, is used as benchmark and calculated using a well-established single blow technique. A sample...

  16. Normalized Urinary Flow at Puberty after Tubularized Incised Plate Urethroplasty for Hypospadias in Childhood.

    Science.gov (United States)

    Andersson, Marie; Doroszkiewicz, Monika; Arfwidsson, Charlotte; Abrahamsson, Kate; Sillén, Ulla; Holmdahl, Gundela

    2015-11-01

    An obstructive urinary flow pattern is frequently seen after tubularized incised plate urethroplasty for hypospadias. However, the significance of this finding has not been determined and long-term results are few. We describe postoperative long-term uroflowmetry results after puberty in males who underwent tubularized incised plate urethroplasty in childhood. A total of 126 boys underwent tubularized incised plate urethroplasty for distal penile to mid shaft hypospadias at Queen Silvia Children's Hospital in Gothenburg between 1999 and 2003. Of the patients 48 were toilet trained at surgery. We report on 40 patients who had data available at 2 and 12 months postoperatively, 7 years postoperatively and at puberty (median age 15.0 years, range 13.7 to 17.1). Of the patients 31 had distal and 9 had mid penile hypospadias. Clinical examination, urinary medical history, uroflowmetry and ultrasound measuring residual urine were performed. Maximum urinary flow was correlated to age and voided volume, using Miskolc nomograms for comparison of percentiles. At 1 year postoperatively 15 boys (37.5%) had normal urinary flow (above 25th percentile), compared to 16 (40%) at 7 years and 38 (95%) at puberty (p puberty for boys with hypospadias treated with tubularized incised plate urethroplasty. Unless symptoms occur, a conservative approach seems preferable. Copyright © 2015 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  17. Natural convective magneto-nanofluid flow and radiative heat transfer past a moving vertical plate

    Directory of Open Access Journals (Sweden)

    S. Das

    2015-03-01

    Full Text Available An investigation of the hydromagnetic boundary layer flow past a moving vertical plate in nanofluids in the presence of a uniform transverse magnetic field and thermal radiation has been carried out. Three different types of water-based nanofluids containing copper, aluminum oxide and titanium dioxide are taken into consideration. The governing equations are solved using Laplace transform technique and the solutions are presented in closed form. The numerical values of nanofluid temperature, velocity, the rate of heat transfer and the shear stress at the plate are presented graphically for several values of the pertinent parameters. The present study finds applications in engineering devices.

  18. Analysis of thermal dispersion in an array of parallel plates with fully-developed laminar flow

    International Nuclear Information System (INIS)

    Xu Jiaying; Lu Tianjian; Hodson, Howard P.; Fleck, Norman A.

    2010-01-01

    The effect of thermal dispersion upon heat transfer across a periodic array of parallel plates is studied. Three basic heat transfer problems are addressed, each for steady, fully-developed, laminar fluid flow: (a) transient heat transfer due to an arbitrary initial temperature distribution within the fluid, (b) steady heat transfer with constant heat flux on all plate surfaces, and (c) steady heat transfer with constant wall temperatures. For problems (a) and (b), the effective thermal dispersivity scales with the Peclet number Pe according to 1 + CPe 2 , where the coefficient C is independent of Pe. For problem (c) the coefficient C is a function of Pe.

  19. MHD Boundary Layer Slip Flow and Heat Transfer over a Flat Plate

    International Nuclear Information System (INIS)

    Bhattacharyya, Krishnendu; Mukhopadhyay, Swati; Layek, G. C.

    2011-01-01

    An analysis of magnetohydrodynamic (MHD) boundary layer flow and heat transfer over a flat plate with slip condition at the boundary is presented. A complete self-similar set of equations are obtained from the governing equations using similarity transformations and are solved by a shooting method. In the boundary slip condition no local similarity occurs. Velocity and temperature distributions within the boundary layer are presented. Our analysis reveals that the increase of magnetic and slip parameters reduce the boundary layer thickness and also enhance the heat transfer from the plate. (fundamental areas of phenomenology(including applications))

  20. Analytic Approximate Solutions for Unsteady Two-Dimensional and Axisymmetric Squeezing Flows between Parallel Plates

    Directory of Open Access Journals (Sweden)

    Mohammad Mehdi Rashidi

    2008-01-01

    Full Text Available The flow of a viscous incompressible fluid between two parallel plates due to the normal motion of the plates is investigated. The unsteady Navier-Stokes equations are reduced to a nonlinear fourth-order differential equation by using similarity solutions. Homotopy analysis method (HAM is used to solve this nonlinear equation analytically. The convergence of the obtained series solution is carefully analyzed. The validity of our solutions is verified by the numerical results obtained by fourth-order Runge-Kutta.

  1. Equivalent linearization method for limit cycle flutter analysis of plate-type structure in axial flow

    International Nuclear Information System (INIS)

    Lu Li; Yang Yiren

    2009-01-01

    The responses and limit cycle flutter of a plate-type structure with cubic stiffness in viscous flow were studied. The continuous system was dispersed by utilizing Galerkin Method. The equivalent linearization concept was performed to predict the ranges of limit cycle flutter velocities. The coupled map of flutter amplitude-equivalent linear stiffness-critical velocity was used to analyze the stability of limit cycle flutter. The theoretical results agree well with the results of numerical integration, which indicates that the equivalent linearization concept is available to the analysis of limit cycle flutter of plate-type structure. (authors)

  2. Heat transfer and flow analysis of nanofluid flow between parallel plates in presence of variable magnetic field using HPM

    Energy Technology Data Exchange (ETDEWEB)

    Hatami, M., E-mail: m.hatami@tue.nl [Esfarayen University of Technology, Mechanical Engineering Department, Esfarayen, North Khorasan (Iran, Islamic Republic of); Jing, Dengwei; Song, Dongxing [International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi' an 710049 (China); Sheikholeslami, M.; Ganji, D.D. [Department of Mechanical Engineering, Babol University of Technology, Babol (Iran, Islamic Republic of)

    2015-12-15

    In this study, effect of variable magnetic field on nanofluid flow and heat transfer analysis between two parallel disks is investigated. By using the appropriate transformation for the velocity, temperature and concentration, the basic equations governing the flow, heat and mass transfer were reduced to a set of ordinary differential equations. These equations subjected to the associated boundary conditions were solved analytically using Homotopy perturbation method. The analytical investigation is carried out for different governing parameters namely: squeeze number, suction parameter, Hartmann number, Brownian motion parameter, thermophrotic parameter and Lewis number. Results show that Nusselt number has direct relationship with Brownian motion parameter and thermophrotic parameter but it is a decreasing function of squeeze number, suction parameter, Hartmann number and Lewis number. - Highlights: • Heat and mass transfer of nanofluids between parallel plates investigated. • A variable magnetic field is applied on the plates. • Governing equations are solved analytically. • Effects of physical parameters are discussed on the Nusselt number.

  3. Heat transfer and flow analysis of nanofluid flow between parallel plates in presence of variable magnetic field using HPM

    International Nuclear Information System (INIS)

    Hatami, M.; Jing, Dengwei; Song, Dongxing; Sheikholeslami, M.; Ganji, D.D.

    2015-01-01

    In this study, effect of variable magnetic field on nanofluid flow and heat transfer analysis between two parallel disks is investigated. By using the appropriate transformation for the velocity, temperature and concentration, the basic equations governing the flow, heat and mass transfer were reduced to a set of ordinary differential equations. These equations subjected to the associated boundary conditions were solved analytically using Homotopy perturbation method. The analytical investigation is carried out for different governing parameters namely: squeeze number, suction parameter, Hartmann number, Brownian motion parameter, thermophrotic parameter and Lewis number. Results show that Nusselt number has direct relationship with Brownian motion parameter and thermophrotic parameter but it is a decreasing function of squeeze number, suction parameter, Hartmann number and Lewis number. - Highlights: • Heat and mass transfer of nanofluids between parallel plates investigated. • A variable magnetic field is applied on the plates. • Governing equations are solved analytically. • Effects of physical parameters are discussed on the Nusselt number

  4. A steady-state continuous flow chamber for the study of daytime and nighttime chemistry under atmospherically relevant NO levels

    Science.gov (United States)

    Zhang, Xuan; Ortega, John; Huang, Yuanlong; Shertz, Stephen; Tyndall, Geoffrey S.; Orlando, John J.

    2018-05-01

    Experiments performed in laboratory chambers have contributed significantly to the understanding of the fundamental kinetics and mechanisms of the chemical reactions occurring in the atmosphere. Two chemical regimes, classified as high-NO vs. zero-NO conditions, have been extensively studied in previous chamber experiments. Results derived from these two chemical scenarios are widely parameterized in chemical transport models to represent key atmospheric processes in urban and pristine environments. As the anthropogenic NOx emissions in the United States have decreased remarkably in the past few decades, the classic high-NO and zero-NO conditions are no longer applicable to many regions that are constantly impacted by both polluted and background air masses. We present here the development and characterization of the NCAR Atmospheric Simulation Chamber, which is operated in steady-state continuous flow mode for the study of atmospheric chemistry under intermediate NO conditions. This particular chemical regime is characterized by constant sub-ppb levels of NO and can be created in the chamber by precise control of the inflow NO concentration and the ratio of chamber mixing to residence timescales. Over the range of conditions achievable in the chamber, the lifetime of peroxy radicals (RO2), a key intermediate from the atmospheric degradation of volatile organic compounds (VOCs), can be extended to several minutes, and a diverse array of reaction pathways, including unimolecular pathways and bimolecular reactions with NO and HO2, can thus be explored. Characterization experiments under photolytic and dark conditions were performed and, in conjunction with model predictions, provide a basis for interpretation of prevailing atmospheric processes in environments with intertwined biogenic and anthropogenic activities. We demonstrate the proof of concept of the steady-state continuous flow chamber operation through measurements of major first-generation products

  5. A steady-state continuous flow chamber for the study of daytime and nighttime chemistry under atmospherically relevant NO levels

    Directory of Open Access Journals (Sweden)

    X. Zhang

    2018-05-01

    Full Text Available Experiments performed in laboratory chambers have contributed significantly to the understanding of the fundamental kinetics and mechanisms of the chemical reactions occurring in the atmosphere. Two chemical regimes, classified as high-NO vs. zero-NO conditions, have been extensively studied in previous chamber experiments. Results derived from these two chemical scenarios are widely parameterized in chemical transport models to represent key atmospheric processes in urban and pristine environments. As the anthropogenic NOx emissions in the United States have decreased remarkably in the past few decades, the classic high-NO and zero-NO conditions are no longer applicable to many regions that are constantly impacted by both polluted and background air masses. We present here the development and characterization of the NCAR Atmospheric Simulation Chamber, which is operated in steady-state continuous flow mode for the study of atmospheric chemistry under intermediate NO conditions. This particular chemical regime is characterized by constant sub-ppb levels of NO and can be created in the chamber by precise control of the inflow NO concentration and the ratio of chamber mixing to residence timescales. Over the range of conditions achievable in the chamber, the lifetime of peroxy radicals (RO2, a key intermediate from the atmospheric degradation of volatile organic compounds (VOCs, can be extended to several minutes, and a diverse array of reaction pathways, including unimolecular pathways and bimolecular reactions with NO and HO2, can thus be explored. Characterization experiments under photolytic and dark conditions were performed and, in conjunction with model predictions, provide a basis for interpretation of prevailing atmospheric processes in environments with intertwined biogenic and anthropogenic activities. We demonstrate the proof of concept of the steady-state continuous flow chamber operation through measurements of major first

  6. Fluid Flow and Infrared Image Analyses on Endwall Fitted with Short Rectangular Plate Fin

    Institute of Scientific and Technical Information of China (English)

    Kenyu OYAKAWA; Islam Md. DIDARUL; Minoru YAGA

    2006-01-01

    An experimental investigation is carried out to study fluid flow and heat transfer characteristics on the endwall fitted with arrays ( 7 × 7 ) of short rectangular plate fins of different pattern (co-angular and zigzag) for different pitch ratio. Experiments were conducted in a rectangular duct of 50 mm height for an air flow of Reynolds number ranged from 18750 to 62500 based on the equivalent diameter and air velocity of the duct. Infrared image analysis technique was employed to make clear the characteristics of local heat transfer coefficients on fin base, endwall and overall surface. Flow pattern around the short rectangular plates were visualized by inducing fluorescent dye in a water channel and longitudinal vortices were observed. Increasing the distance between plates in flow direction causes heat transfer enhancement for co-angular pattern, while decreasing the distance causes heat transfer enhancement for zigzag pattern. Zigzag pattern with pitch ratio 2 is found to be more effective in heat transfer enhancement than any other cases investigated.

  7. An Investigation of Ionic Flows in a Sphere-Plate Electrode Gap

    International Nuclear Information System (INIS)

    Alisoy, H. Z.; Alagoz, B. B.; Alagoz, S.; Alisoy, G. T.

    2013-01-01

    This paper presents analyses of ion flow characteristics and ion discharge pulses in a sphere-ground plate electrode system. As a result of variation in electric field intensity in the electrode gap, the ion flows towards electrodes generate non-uniform discharging pulses. Inspection of these pulses provides useful information on ionic stream kinetics, the effective thickness of ion cover around electrodes, and the timing of ion clouds discharge pulse sequences. A finite difference time domain (FDTD) based space-charge motion simulation is used for the numerical analysis of the spatio-temporal development of ionic flows following the first Townsend avalanche, and the simulation results demonstrate expansion of the positive ion flow and compression of the negative ion flow, which results in non-uniform discharge pulse characteristics

  8. An Investigation of Ionic Flows in a Sphere-Plate Electrode Gap

    Science.gov (United States)

    Z. Alisoy, H.; Alagoz, S.; T. Alisoy, G.; B. Alagoz, B.

    2013-10-01

    This paper presents analyses of ion flow characteristics and ion discharge pulses in a sphere-ground plate electrode system. As a result of variation in electric field intensity in the electrode gap, the ion flows towards electrodes generate non-uniform discharging pulses. Inspection of these pulses provides useful information on ionic stream kinetics, the effective thickness of ion cover around electrodes, and the timing of ion clouds discharge pulse sequences. A finite difference time domain (FDTD) based space-charge motion simulation is used for the numerical analysis of the spatio-temporal development of ionic flows following the first Townsend avalanche, and the simulation results demonstrate expansion of the positive ion flow and compression of the negative ion flow, which results in non-uniform discharge pulse characteristics.

  9. Numerical modeling and investigation of two-phase reactive flow in a high-low pressure chambers system

    International Nuclear Information System (INIS)

    Cheng, Cheng; Zhang, Xiaobing

    2016-01-01

    Highlights: • A novel two-dimensional two-phase flow model is established for the high-low pressure chambers system. • A strong packing of particles is observed at the projectile base and will cause the pressure to rise faster. • Different length–diameter ratios can affect the flow behavior through the vent-holes obviously. • The muzzle velocity decreases with the length–diameter ratio of the high-pressure chamber. - Abstract: A high-low pressure chambers system is proposed to meet the demands of low launch acceleration for informative equipment in many special fields such as Aeronautics, Astronautics and Weaponry. A two-dimensional two-phase flow numerical model is established to describe the complex physical process based on a modified two-fluid theory, which takes into account gas production, interphase drag, intergranular stress, and heat transfer between two phases. In order to reduce the computational cost, the parameters in the high-pressure chamber at the instant the vent-holes open are calculated by the zero-dimensional model as the initial conditions for the two-phase flow simulation in the high-low pressure chambers system. The simulation results reveal good agreement with the experiments and the launch acceleration of a projectile can be improved by this system. The propellant particles can be tracked clearly in both chambers and a strong packing of particles at the base of projectile will cause the pressure to rise faster than at other areas both in the axis and radial directions. The length–diameter ratio of the high-pressure chamber (a typical multi-dimensional parameter) is investigated. Different length–diameter ratios can affect the maximum pressure drop and the loss of total pressure impulse through the vent-hole, then the muzzle velocity and the launch acceleration of projectiles can be influenced directly. This article puts forward a new prediction tool for the understanding and design of transient processes in high-low pressure

  10. Development of Integrally Molded Bipolar Plates for All-Vanadium Redox Flow Batteries

    Directory of Open Access Journals (Sweden)

    Chih-Hsun Chang

    2016-05-01

    Full Text Available All-vanadium redox flow batteries (VRBs are potential energy storage systems for renewable power sources because of their flexible design, deep discharge capacity, quick response time, and long cycle life. To minimize the energy loss due to the shunt current, in a traditional design, a flow field is machined on two electrically insulated frames with a graphite plate in between. A traditional bipolar plate (BP of a VRB consists of many components, and thus, the assembly process is time consuming. In this study, an integrally molded BP is designed and fabricated to minimize the manufacturing cost. First, the effects of the mold design and injection parameters on frame formability were analyzed by simulation. Second, a new graphite plate design for integral molding was proposed, and finally, two integrally molded BPs were fabricated and compared. Results show that gate position significantly affects air traps and the maximum volume shrinkage occurs at the corners of a BP. The volume shrinkage can be reduced using a large graphite plate embedded within the frame.

  11. Numerical analysis of the flow field in a sloshing tank with a horizontal perforated plate

    Science.gov (United States)

    Jin, Heng; Liu, Yong; Li, Huajun; Fu, Qiang

    2017-08-01

    Liquid sloshing is a type of free surface flow inside a partially filled water tank. Sloshing exerts a significant effect on the safety of liquid transport systems; in particular, it may cause large hydrodynamic loads when the frequency of the tank motion is close to the natural frequency of the tank. Perforated plates have recently been used to suppress the violent movement of liquids in a sloshing tank at resonant conditions. In this study, a numerical model based on OpenFOAM (Open Source Field Operation and Manipulation), an open source computed fluid dynamic code, is used to investigate resonant sloshing in a swaying tank with a submerged horizontal perforated plate. The numerical results of the free surface elevations are first verified using experimental data, and then the flow characteristics around the perforated plate and the fluid velocity distribution in the entire tank are examined using numerical examples. The results clearly show differences in sloshing motions under first-order and third-order resonant frequencies. This study provides a better understanding of the energy dissipation mechanism of a horizontal perforated plate in a swaying tank.

  12. Initial Unsteady Free Convective Flow Past an Infinite Vertical Plate with Radiation and Mass Transfer Effects

    Directory of Open Access Journals (Sweden)

    Khan A.

    2017-12-01

    Full Text Available An exact solution and analysis of an initial unsteady two dimensional free convection flow, heat and mass transfer in the presence of thermal radiation along an infinite fixed vertical plate when the plate temperature is instantaneously raised, is presented. The fluid considered is a gray, absorbing emitting radiation but a nonscattering medium. Three cases have been discussed, in particular, namely, (i when, the plate temperature is instantaneously raised to a higher constant value, (ii when, the plate temperature varies linearly with time and (iii when, the plate temperature varies non-linearly with time. A close form general solution for all the cases has been obtained in terms of repeated integrals of error functions. In two particular cases, the solutions in terms of the repeated integrals of error functions have been further simplified to forms containing only error functions. It is observed that for an increase in the radiation parameter N or a decrease in the Grashof number Gr or Gm, there is a fall in the velocity or temperature, but compared to the no radiation case or no diffusing species, there is a rise in the velocity and temperature of the fluid.

  13. A form of MHD universal equations of unsteady incompressible fluid flow with variable elctroconductivity on heated moving plate

    Directory of Open Access Journals (Sweden)

    Boričić Zoran

    2005-01-01

    Full Text Available This paper deals with laminar, unsteady flow of viscous, incompressible and electro conductive fluid caused by variable motion of flat plate. Fluid electro conductivity is variable. Velocity of the plate is time function. Plate moves in its own plane and in "still" fluid. Present external magnetic filed is perpendicular to the plate. Plate temperature is a function of longitudinal coordinate and time. Viscous dissipation, Joule heat, Hole and polarization effects are neglected. For obtaining of universal equations system general similarity method is used as well as impulse and energy equation of described problem.

  14. Irradiation chamber for photoactivation patient treatment system

    International Nuclear Information System (INIS)

    Lee, K.H.; Troutner, V.H.; Goss, J.; King, M.J.

    1988-01-01

    A flat plate irradiation chamber is described for use in a patient treatment system for altering cells, including treating the cells with a photoactivatable agent and passing the cells and the agent through a field of photoactivating radiation whereby the agent is caused to be activated and to affect the cells. The agent and the cells are contained in the irradiation chamber during irradiation. The flat plate irradiation chamber comprises: a rigid top sheet matably joined with a rigid bottom sheet, forming therebetween a rigid serpentine pathway for conducting the cells through the field of radiation; and pump block means for holding tubing means in fluid communication with the serpentine pathway and adapted for engaging a peristaltic pump whereby rotation of the pump causes the cells to flow through the serpentine pathway, and wherein the chamber is removable from the system and disposable

  15. Magnetohydrodynamic mixed convective slip flow over an inclined porous plate with viscous dissipation and Joule heating

    Directory of Open Access Journals (Sweden)

    S. Das

    2015-06-01

    Full Text Available The combined effects of viscous dissipation and Joule heating on the momentum and thermal transport for the magnetohydrodynamic flow past an inclined plate in both aiding and opposing buoyancy situations have been carried out. The governing non-linear partial differential equations are transformed into a system of coupled non-linear ordinary differential equations using similarity transformations and then solved numerically using the Runge–Kutta fourth order method with shooting technique. Numerical results are obtained for the fluid velocity, temperature as well as the shear stress and the rate of heat transfer at the plate. The results show that there are significant effects of pertinent parameters on the flow fields.

  16. The magnetohydrodynamic flow near a time-varying accelerated porous plate

    International Nuclear Information System (INIS)

    Roy, A.; Das, A.K.

    1985-01-01

    This paper confines to the study of the flow of an electrically conducting incompressible viscous liquid due to the varying motion of an infinite nonconducting porous flat pjate in the presence of a transverse magnetic field under the following assumptions: (1) the fluid flows subject to uniform section, (2) the magnetic Reynold number is equai to the viscous Reynold number, (3) the plate moves in its own plane with the velocity of esup(at)tsup(n) (n is an integer and α > a), (4) the Alfven velocity is less than the suction velocity. The induced magnetic field produced by the motion is taken into account. General expressions of the velocity and skinfriction have been obtained when the plate moves with the velocity esup(at)tsup(n). Several particular cases have been studied. (authors)

  17. A compact multi-plate fission chamber for the simultaneous measurement of 233U capture and fission cross-sections

    Directory of Open Access Journals (Sweden)

    Bacak M.

    2017-01-01

    Full Text Available 233U plays the essential role of fissile nucleus in the Th-U fuel cycle. A particularity of 233U is its small neutron capture cross-section which is about one order of magnitude lower than the fission cross-section on average. Therefore, the accuracy in the measurement of the 233U capture cross-section essentially relies on efficient capture-fission discrimination thus a combined setup of fission and γ-detectors is needed. At CERN n_TOF the Total Absorption Calorimeter (TAC coupled with compact fission detectors is used. Previously used MicroMegas (MGAS detectors showed significant γ-background issues above 100 eV coming from the copper mesh. A new measurement campaign of the 233U capture cross-section and alpha ratio is planned at the CERN n_TOF facility. For this measurement, a novel cylindrical multi ionization cell chamber was developed in order to provide a compact solution for 14 active targets read out by 8 anodes. Due to the high specific activity of 233U fast timing properties are required and achieved with the use of customized electronics and the very fast ionizing gas CF4 together with a high electric field strength. This paper describes the new fission chamber and the results of the first tests with neutrons at GELINA proving that it is suitable for the 233U measurement.

  18. The solutions of Navier-Stokes equations in squeezing flow between parallel plates

    Czech Academy of Sciences Publication Activity Database

    Petrov, A. G.; Kharlamova, Irina

    2014-01-01

    Roč. 48, November–December (2014), s. 40-48 ISSN 0997-7546 Grant - others:Russian Foundation for Basic Research(RU) 14-01- 00818; Russian Foundation for Basic Research(RU) 14-01-00892 Institutional support: RVO:67985874 Keywords : closed form solution * Navier-Stokes equations * squeezing flow between plates * counterflow Subject RIV: BK - Fluid Dynamics Impact factor: 1.656, year: 2014

  19. Magnetohydrodynamic flow of a rarefied gas near a time-varying accelerated plate

    International Nuclear Information System (INIS)

    Mishra, S.P.; Mohapatra, Priti

    1975-01-01

    The flow of an electrically conducting rarefied gas due to the time-varying motion of an infinite flat plate has been studied in the presence of a uniform magnetic field. The magnetic lines of force are taken to be fixed relative to the fluid. General expressions of the velocity and the skin friction have been compared by means of some qraphs and tables. (author)

  20. Cost and performance prospects for composite bipolar plates in fuel cells and redox flow batteries

    Science.gov (United States)

    Minke, Christine; Hickmann, Thorsten; dos Santos, Antonio R.; Kunz, Ulrich; Turek, Thomas

    2016-02-01

    Carbon-polymer-composite bipolar plates (BPP) are suitable for fuel cell and flow battery applications. The advantages of both components are combined in a product with high electrical conductivity and good processability in convenient polymer forming processes. In a comprehensive techno-economic analysis of materials and production processes cost factors are quantified. For the first time a technical cost model for BPP is set up with tight integration of material characterization measurements.

  1. Polymer electrolyte membrane fuel cell (PEMFC) flow field plate: design, materials and characterisation

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, P.J.; Pollet, B.G. [PEM Fuel Cell Research Group, School of Chemical Engineering, University of Birmingham, Edgbaston, B15 2TT (United Kingdom)

    2010-08-15

    This review describes some recent developments in the area of flow field plates (FFPs) for proton exchange membrane fuel cells (PEMFCs). The function, parameters and design of FFPs in PEM fuel cells are outlined and considered in light of their performance. FFP materials and manufacturing methods are discussed and current in situ and ex situ characterisation techniques are described. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  2. PPC's (parallel plate chambers) y su aplicación en calorimetría a bajo angulo en experimentos en el LHC

    CERN Document Server

    Fouz-Iglesias, M C

    1997-01-01

    In the LHC working conditions especific detector requirements are fast response, high rate capability and radiation resistance. This is particularly important for detectors in the low angle regions such as the Very Forward Hadron Calorimeter ( VF ) of CMS , located at 11 m from the interaction point and covering the pseudorapidity region between 3 and 5. The major goals of this calorimeters are to improve the measured of the transverse energy ( Et) and the missing transverse energy ( Etmiss) ( important for Higgs searches, Top-quark physics, SUSY searches, etc) and the detection and reconstruction of forward jets characteristics of some importants process (such the TeV jets coming from the WW(ZZ) fusion Higgs production mechanism ). The requirements for this calorimeter are a moderate energy resolution and an adequate segmentation for forward jet tagging and reconstruction are needed. The purpose of this thesis is to show that calorimeters based on the Parallel Plate Chambers ( PPC. - Gaseous detector with pl...

  3. NINO An ultra-fast and low-power front-end amplifier/discriminator ASIC designed for the multigap resistive plate chamber

    CERN Document Server

    Anghinolfi, F; Martemyanov, A N; Usenko, E; Wenninger, Horst; Williams, M C S; Zichichi, A

    2004-01-01

    For the full exploitation of the excellent timing properties of the Multigap Resistive Plate Chamber (MRPC), front-end electronics with special characteristics are needed. These are (a) differential input, to profit from the differential signal from the MRPC (b) a fast amplifier with less than 1 ns peaking time and (c) input charge measurement by Time-Over-Threshold for slewing correction. An 8- channel amplifier and discriminator chip has been developed to match these requirements. This is the NINO ASIC, fabricated with 0.25 omegam CMOS technology. The power requirement at 40mW/channel is low. Results on the performance of the MRPCs using the NINO ASIC are presented. Typical time resolution a of the MRPC system is in the 50 ps range, with an efficiency of 99.9%.

  4. Studies on multigap resistive plate chamber prototypes for the new NeuLAND detector at the R3B experiment at FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Elvers, Michael; Endres, Janis; Zilges, Andreas [IKP, Universitaet Koeln (Germany); Aumann, Tom; Boretzky, Konstanze; Hehner, Joerg; Heil, Michael; Prokopowicz, Wawrczek; Reifarth, Rene; Schrieder, Gerhard [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany); Bemmerer, Daniel; Stach, Daniel; Wagner, Andreas; Yakorev, Dmitry [Forschungszentrum Dresden-Rossendorf (FZD), Dresden (Germany); Kratz, Jens Volker; Rossi, Dominic [Johannes-Gutenberg-Universitaet, Mainz (Germany)

    2009-07-01

    The NeuLAND detector is part of the R3B experiment at FAIR and will detect neutrons between 0.2 and 1 GeV. The high energy neutrons are converted to charged particles, mainly protons, which are detected by Multigap Resistive Plate Chambers (MRPC). For the detector, a time resolution of {sigma}{sub t} < 100 ps and a position resolution of {sigma}{sub x,y,z} {approx}1 cm is required for given flight paths in the range from 10 to 35 m. An active area of 2 x 2 m{sup 2} of the neutron detector at a distance of 12.5 m to the target will match the angular acceptance of {+-}80 mrad for the neutrons defined by the gap of the superconducting dipole magnet. The salient features of the prototypes are described, as well as electrical measurements and studies with cosmic rays.

  5. Simulation and prototyping of 2 m long resistive plate chambers for detection of fast neutrons and multi-neutron event identification

    Energy Technology Data Exchange (ETDEWEB)

    Elekes, Z., E-mail: z.elekes@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Aumann, T. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Technische Universität Darmstadt, Darmstadt (Germany); Bemmerer, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Boretzky, K. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Caesar, C. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Technische Universität Darmstadt, Darmstadt (Germany); Cowan, T.C. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universität Dresden, Dresden (Germany); Hehner, J.; Heil, M. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Kempe, M. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Rossi, D. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Röder, M. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universität Dresden, Dresden (Germany); Simon, H. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Sobiella, M.; Stach, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Reinhardt, T. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universität Dresden, Dresden (Germany); Wagner, A.; Yakorev, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Zilges, A. [Universität zu Köln, Köln (Germany); Zuber, K. [Technische Universität Dresden, Dresden (Germany)

    2013-02-11

    Resistive plate chamber (RPC) prototypes of 2 m length were simulated and built. The experimental tests using a 31 MeV electron beam, discussed in details, showed an efficiency higher than 90% and an excellent time resolution of around σ=100ps. Furthermore, comprehensive simulations were performed by GEANT4 toolkit in order to study the possible use of these RPCs for fast neutron (200 MeV–1 GeV) detection and multi-neutron event identification. The validation of simulation parameters was carried out via a comparison to experimental data. A possible setup for invariant mass spectroscopy of multi-neutron emission is presented and the characteristics are discussed. The results show that the setup has a high detection efficiency. Its capability of determining the momentum of the outgoing neutrons and reconstructing the relative energy between the fragments from nuclear reactions is demonstrated for different scenarios.

  6. Radiated flow of chemically reacting nanoliquid with an induced magnetic field across a permeable vertical plate

    Directory of Open Access Journals (Sweden)

    B. Mahanthesh

    Full Text Available Impact of induced magnetic field over a flat porous plate by utilizing incompressible water-copper nanoliquid is examined analytically. Flow is supposed to be laminar, steady and two-dimensional. The plate is subjected to a regular free stream velocity as well as suction velocity. Flow formulation is developed by considering Maxwell–Garnetts (MG and Brinkman models of nanoliquid. Impacts of thermal radiation, viscous dissipation, temperature dependent heat source/sink and first order chemical reaction are also retained. The subjected non-linear problems are non-dimensionalized and analytic solutions are presented via series expansion method. The graphs are plotted to analyze the influence of pertinent parameters on flow, magnetism, heat and mass transfer fields as well as friction factor, current density, Nusselt and Sherwood numbers. It is found that friction factor at the plate is more for larger magnetic Prandtl number. Also the rate of heat transfer decayed with increasing nanoparticles volume fraction and the strength of magnetism. Keywords: Induced magnetic field, Nanoliquids, Heat source/sink, Series expansion method, Chemical reaction, Thermal radiation

  7. LDA measurement of droplet behavior across tie plate during dispersed flow portion of loca reflood

    International Nuclear Information System (INIS)

    Lee, S.L.; Srinivasan, J.; Cho, S.K.

    1980-01-01

    The flow of an air-water droplet dispersion in a simulated 3-D test section in the reflood portion of LOCA was studied. For this purpose, a new scheme of Laser-Doppler Anemometry for the simultaneous measurement of size and velocity of large-size [0.5 mm-6 mm] droplets was developed and utilized. It was observed that the size distribution of the reentrained droplets depends mainly on the flow regimes and is essentially independent of that of the incoming dispersion below the tie plate. 8 refs

  8. Numerical analysis of the flow field in the pump chamber of a centrifugal pump with back blades

    International Nuclear Information System (INIS)

    Cao, L; Wang, Z W; Luo, Y Y; Liu, M

    2013-01-01

    Black blade is frequently used as a non-contact seal structure in centrifugal pumps transporting solid-liquid two-phase flow. However, it will disturb the flow in the pump and affect the pump performance. Numerical simulation for 3D turbulence in whole flow passage of a centrifugal pump with back blades was carried out based on RANS method, with SST k-ω turbulence model and SIMPLEC algorithm. Calculation for a similar pump without back blades was also carried out as a comparison. Boundary condition was improved due to the existence of back blade. The influence of back blades on the flow field was analysed qualitatively for three typical conditions. Meanwhile the leakage rate was calculated for several conditions and the effect of back blades was discussed. According to the results, compared with the condition without back blades, it could be seen that back blade apparently changed the flow state in the front chamber, improved near the front shroud and worsened near the pump cover. Velocity was increased and more fluid, which flowed into the front chamber from the pump cover side, flowed back to the spiral casing from the impeller shroud side. With the increase of discharge, the absolute value of leakage rate first went up and then dropped, as a consequence of the combination of two factors, discharge and differential pressure between the impeller outlet and inlet. The seal effect of back blades is most obvious under small discharge condition, and the leakage loss diminished as discharge increased

  9. Modeling of atomization and distribution of drop-liquid fuel in unsteady swirling flows in a combustion chamber and free space

    Science.gov (United States)

    Sviridenkov, A. A.; Toktaliev, P. D.; Tretyakov, V. V.

    2018-03-01

    Numerical and experimental research of atomization and propagation of drop-liquid phase in swirling flow behind the frontal device of combustion chamber was performed. Numerical procedure was based on steady and unsteady Reynolds equations solution. It's shown that better agreement with experimental data could be obtained with unsteady approach. Fractional time step method was implemented to solve Reynolds equations. Models of primary and secondary breakup of liquid fuel jet in swirling flows are formulated and tested. Typical mean sizes of fuel droplets for base operational regime of swirling device and combustion chamber were calculated. Comparison of main features of internal swirling flow in combustion chamber with unbounded swirling flow was made.

  10. Flow induced deformation and collapse of a thin rectangular plate with application to the Engineering Test Reactor nuclear fuel elements

    International Nuclear Information System (INIS)

    Davis, C.D.

    1981-01-01

    This work examines a single flat fuel plate bounded by two channels and determines static plate deflections, resultant forces and bending stresses due to pressure differential and hydrodynamic loadings. The classical then reactangular plate equations are used to model the fuel plate. These equations contain as an input the hydrodynamic loading function for modeling the fluid-structural interaction. Two models of the channel flow are developed. One assumes the accelerating potential core flow is laminar with developing two-dimensional laminar boundary layers being formed on the channel walls. The Schlichting entry length solution for developing laminar flow is found to be valid the entire length of the channel. The second model assumes the core flow is fully-developed turbulent the entire length of the channel. Hydrodynamic loading functions are developed for both flow models containing parameters for fluid density, fluid velocity, Reynolds number and channel and plate dimensions. Hence the effects of each parameter can be examined independently. A criterion is developed for predicting ETR fuel plate collapse at high channel flow velocities, 1067 cm/s (420 in/sec) (R/sub e/ = 60,000). The criterion predicts that in order to prevent ETR plate collapse the inlet velocities between channels must not differ by more than 2%

  11. Investigation of Three-Dimensional Axisymmetric Unsteady Stagnation-Point Flow and Heat Transfer Impinging on an Accelerated Flat Plate

    OpenAIRE

    ali shokrgozar abbasi; Asghar Baradaran Rahimi; Hamidreza Mozayeni

    2016-01-01

    General formulation and solution of Navier-Stokes and energy equations are sought in the study of threedimensional axisymmetric unsteady stagnation-point flow and heat transfer impinging on a flat plate when the plate is moving with variable velocity and acceleration towards the main stream or away from it. As an application, among others, this accelerated plate can be assumed as a solidification front which is being formed with variable velocity. An external fluid, along z - directi...

  12. Estimates of Two-Phase Flow Parameters in the Cyclone Chamber

    Directory of Open Access Journals (Sweden)

    Razva Aleksandr

    2016-01-01

    Full Text Available It provides analysis of methods for assessing circumferential speeds distribution of pressure in the cyclone chamber. It is shown that for cylindrical chambers of less than two diameters and the inlet section of at least 0.1 square cross section the maximum peripheral speed and rate distributions circumferential speeds along the current line is not changed. Analysis of the distribution shows that the concentration of small particles that are typical for gas dedusting systems have a significant impact on the distribution of pressure, vacuum and on the axis of the absolute value decreases toward dust of output section unlike the swirl chambers fuel combustion.

  13. Auto-ignition of methane-air mixtures flowing along an array of thin catalytic plates

    Science.gov (United States)

    Treviño, C.

    2010-12-01

    In this paper, the heterogeneous ignition of a methane-air mixture flowing along an infinite array of catalytic parallel plates has been studied by inclusion of gas expansion effects and the finite heat conduction on the plates. The system of equations considers the full compressible Navier-Stokes equations coupled with the energy equations of the plates. The gas expansion effects which arise from temperature changes have been considered. The heterogeneous kinetics considers the adsorption and desorption reactions for both reactants. The limits of large and small longitudinal thermal conductance of the plate material are analyzed and the critical conditions for ignition are obtained in closed form. The governing equations are solved numerically using finite differences. The results show that ignition is more easily produced as the longitudinal wall thermal conductance increases, and the effects of the gas expansion on the catalytic ignition process are rather small due to the large value of the activation energy of the desorption reaction of adsorbed oxygen atoms.

  14. Enhanced desalination performance of membrane capacitive deionization cells by packing the flow chamber with granular activated carbon.

    Science.gov (United States)

    Bian, Yanhong; Yang, Xufei; Liang, Peng; Jiang, Yong; Zhang, Changyong; Huang, Xia

    2015-11-15

    A new design of membrane capacitive deionization (MCDI) cell was constructed by packing the cell's flow chamber with granular activated carbon (GAC). The GAC packed-MCDI (GAC-MCDI) delivered higher (1.2-2.5 times) desalination rates than the regular MCDI at all test NaCl concentrations (∼ 100-1000 mg/L). The greatest performance enhancement by packed GAC was observed when treating saline water with an initial NaCl concentration of 100 mg/L. Several different GAC materials were tested and they all exhibited similar enhancement effects. Comparatively, packing the MCDI's flow chamber with glass beads (GB; non-conductive) and graphite granules (GG; conductive but with lower specific surface area than GAC) resulted in inferior desalination performance. Electrochemical impedance spectroscopy (EIS) analysis showed that the GAC-MCDI had considerably smaller internal resistance than the regular MCDI (∼ 19.2 ± 1.2 Ω versus ∼ 1222 ± 15 Ω at 100 mg/L NaCl). The packed GAC also decreased the ionic resistance across the flow chamber (∼ 1.49 ± 0.05 Ω versus ∼ 1130 ± 12 Ω at 100 mg/L NaCl). The electric double layer (EDL) formed on the GAC surface was considered to store salt ions during electrosorption, and facilitate the ion transport in the flow chamber because of the higher ion conductivity in the EDLs than in the bulk solution, thereby enhancing the MCDI's desalination rate. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Computational Fluid Dynamic Pressure Drop Estimation of Flow between Parallel Plates

    Energy Technology Data Exchange (ETDEWEB)

    Son, Hyung Min; Yang, Soo Hyung; Park, Jong Hark [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    Many pool type reactors have forced downward flows inside the core during normal operation; there is a chance of flow inversion when transients occur. During this phase, the flow undergo transition between turbulent and laminar regions where drastic changes take place in terms of momentum and heat transfer, and the decrease in safety margin is usually observed. Additionally, for high Prandtl number fluids such as water, an effect of the velocity profile inside the channel on the temperature distribution is more pronounced over the low Prandtl number ones. This makes the checking of its pressure drop estimation accuracy less important, assuming the code verification is complete. With an advent of powerful computer hardware, engineering applications of computational fluid dynamics (CFD) methods have become quite common these days. Especially for a fully-turbulent and single phase convective heat transfer, the predictability of the commercial codes has matured enough so that many well-known companies adopt those to accelerate a product development cycle and to realize an increased profitability. In contrast to the above, the transition models for the CFD code are still under development, and the most of the models show limited generality and prediction accuracy. Unlike the system codes, the CFD codes estimate the pressure drop from the velocity profile which is obtained by solving momentum conservation equations, and the resulting friction factor can be a representative parameter for a constant cross section channel flow. In addition, the flow inside a rectangular channel with a high span to gap ratio can be approximated by flow inside parallel plates. The computational fluid dynamics simulation on the flow between parallel plates showed reasonable prediction capability for the laminar and the turbulent regime.

  16. An experimental observation of the effect of flow direction for evaporation heat transfer in plate heat exchanger

    International Nuclear Information System (INIS)

    Lin, Yueh-Hung; Li, Guang-Cheng; Yang, Chien-Yuh

    2015-01-01

    This study provides an Infrared Thermal Image observation on the evaporation heat transfer of refrigerant R-410A in plate heat exchanger with various flow arrangement and exit superheat conditions. An experimental method was derived for estimating the superheat region area of two-phase refrigerant evaporation in plate heat exchanger. The experimental results show that the superheat region area for parallel flow is much larger than that for counter flow as that estimated by Yang et al. [9]. There is an early superheated region at the central part of the plate heat exchanger for parallel flow arrangement. This effect is not significant for counter flow arrangement. The Yang et al. [9] method under estimated the superheat area approximately 40%–53% at various flow rates and degree of exit superheat. Even though the flow inside a plate heat exchanger is extremely turbulent because of the chevron flow passages, the assumption of uniform temperature distribution in the cross section normal to the bulk flow direction will cause significant uncertainties for estimating the superheat area for refrigerant evaporating in a plate heat exchanger

  17. Oscillatory electroosmotic flow in a parallel-plate microchannel under asymmetric zeta potentials

    Science.gov (United States)

    Peralta, M.; Arcos, J.; Méndez, F.; Bautista, O.

    2017-06-01

    In this work, we conduct a theoretical analysis of the start-up of an oscillatory electroosmotic flow (EOF) in a parallel-plate microchannel under asymmetric zeta potentials. It is found that the transient evolution of the flow field is controlled by the parameters {R}ω , {R}\\zeta , and \\bar{κ }, which represent the dimensionless frequency, the ratio of the zeta potentials of the microchannel walls, and the electrokinetic parameter, which is defined as the ratio of the microchannel height to the Debye length. The analysis is performed for both low and high zeta potentials; in the former case, an analytical solution is derived, whereas in the latter, a numerical solution is obtained. These solutions provide the fundamental characteristics of the oscillatory EOFs for which, with suitable adjustment of the zeta potential and the dimensionless frequency, the velocity profiles of the fluid flow exhibit symmetric or asymmetric shapes.

  18. Unsteady MHD blood flow through porous medium in a parallel plate channel

    Science.gov (United States)

    Latha, R.; Rushi Kumar, B.

    2017-11-01

    In this study, we have analyzed heat and mass transfer effects on unsteady blood flow through parallel plate channel in a saturated porous medium in the presence of a transverse magnetic field with thermal radiation. The governing higher order nonlinear PDE’S are converted to dimensionless equations using dimensionless variables. The dimensionless equations are then solved analytically using boundary conditions by choosing the axial flow transport and the fields of concentration and temperature apart from the normal velocity as a function of y and t. The effects of different pertinent parameters appeared in this model viz thermal radiation, Prandtl number, Heat source parameter, Hartmann number, Permeability parameter, Decay parameter on axial flow transport and the normal velocity are analyzed in detail.

  19. Radiation effects on flow past an impulsively started vertical plate with variable temperature and mass flux

    Directory of Open Access Journals (Sweden)

    Muthucumaraswamy R.

    2005-01-01

    Full Text Available An analysis is performed to study the thermal radiation effects on unsteady free convective flow over a moving vertical plate in the presence of variable temperature and uniform mass flux. The fluid considered here is a gray, absorbing-emitting radiation but a non-scattering medium. The temperature is raised linearly with time and the concentration level near the plate are raised linearly with time. The dimensionless governing equations are solved using the Laplace transform technique. The velocity and skinfriction are studied for different parameters like the radiation parameter, Schmidt number, thermal Grashof number, mass Grashof number and time. It is observed that the velocity increases with decreasing radiation parameter.

  20. MHD free convection and mass transfer flow over an infinite vertical porous plate with viscous dissipation

    Directory of Open Access Journals (Sweden)

    Poonia Hemant

    2010-01-01

    Full Text Available An unsteady, two-dimensional, hydromagnetic, laminar mixed convective boundary layer flow of an incompressible and electrically-conducting fluid along an infinite vertical plate embedded in the porous medium with heat and mass transfer is analyzed, by taking into account the effect of viscous dissipation. The dimensionless governing equations for this investigation are solved analytically using two-term harmonic and non-harmonic functions. Numerical evaluation of the analytical results is performed and graphical results for velocity, temperature and concentration profiles within the boundary layer are discussed. The results show that increased cooling (Gr > 0 of the plate and the Eckert number leads to a rise in the velocity profile. Also, an increase in Eckert number leads to an increase in the temperature. Effects of Sc on velocity and concentration are discussed and shown graphically.

  1. Slip effects on MHD flow and heat transfer of ferrofluids over a moving flat plate

    Science.gov (United States)

    Ramli, Norshafira; Ahmad, Syakila; Pop, Ioan

    2017-08-01

    In this study, the problem of MHD flow and heat transfer of ferrofluids over a moving flat plate with slip effect and uniform heat flux is considered. The governing ordinary differential equations are solved via shooting method. The effect of slip parameter on the dimensionless velocity, temperature, skin friction and Nusselt numbers are numerically studied for the three selected ferroparticles; magnetite (Fe3O4), cobalt ferrite (CoFe2O4) and Mn-Zn ferrite (Mn-ZnFe2O4) with water-based fluid. The results indicate that dual solutions exist for a plate moving towards the origin. It is found that the slip process delays the boundary layer separation. Moreover, the velocity and thermal boundary-layer thicknesses decrease in the first solution while increase with the increase of the value of slip parameters in second solution.

  2. THE LIQUID NITROGEN SYSTEM FOR CHAMBER A; A CHANGE FROM ORIGINAL FORCED FLOW DESIGN TO A NATURAL FLOW (THERMO SIPHON) SYSTEM

    International Nuclear Information System (INIS)

    Homan, J.; Montz, M.; Ganni, V.; Sidi-Yekhlef, A.; Knudsen, P.; Creel, J.; Arenius, D.; Garcia, S.

    2010-01-01

    NASA at the Johnson Space Center (JSC) in Houston is presently working toward modifying the original forced flow liquid nitrogen cooling system for the thermal shield in the space simulation chamber-A in Building 32 to work as a natural flow (thermo siphon) system. Chamber A is 19.8 m (65 ft) in diameter and 35.66 m (117 ft) high. The LN 2 shroud environment within the chamber is approximately 17.4 m (57 ft) in diameter and 28 m (92 ft) high. The new thermo siphon system will improve the reliability, stability of the system. Also it will reduce the operating temperature and the liquid nitrogen use to operate the system. This paper will present the requirements for the various operating modes. System level thermodynamic comparisons of the existing system to the various options studied and the final option selected will be outlined. A thermal and hydraulic analysis to validate the selected option for the conversion of the current forced flow to natural flow design will be discussed. The proposed modifications to existing system to convert to natural circulation (thermo siphon) system and the design features to help improve the operations, and maintenance of the system will be presented.

  3. Ionization chamber

    International Nuclear Information System (INIS)

    1977-01-01

    An improved ionization chamber type X-ray detector comprises a heavy gas at high pressure disposed between an anode and a cathode. An open grid structure is placed next to the anode and is maintained at a voltage intermediate between the cathode and anode potentials. The electric field which is produced by positive ions drifting towards the cathode is thus shielded from the anode. Current measuring circuits connected to the anode are, therefore, responsive only to electron current flow within the chamber and the recovery time of the chamber is shortened. The grid structure also serves to shield the anode from electrical currents which might otherwise be induced by mechanical vibrations in the ionization chamber structure

  4. Investigation of one-dimensional heat flow in a solarflat plate collector with sun tracing system

    Directory of Open Access Journals (Sweden)

    H Samimi Akhijahani

    2016-09-01

    Full Text Available Introduction Drying is one of the most common methods for storing food and agricultural products. During drying process, free water that causes the growth of microorganisms and spoilage of products is removed from the product. There are several methods for drying of agricultural products. one of the most important methods of investment is drying by using sunlight. Iran is situated at 25- 43oE longitude and mean solar radiation is about 4.9 kwh.m-2.d-1. Because of the proper solar radiations in 95% of the agricultural areas in Iran, solar drying is widely used for drying of fruits and vegetables. The use of solar dryer causes saving in energy consumption and processing costs for drying of products in farms and gardens. Several researchers investigated heat transfer and heat flow in dryers. Selection of appropriate method was carried out for drying of agricultural products using heat pump. Experiments were done and mathematical relationships were estimated to obtain correlation parameters between Reynolds number and Nusselt number for the three cases of solar dryer (cabinet, indirect and combination.The best working conditions were determined for three types of solar collectors (flat, finned and corrugated. In this study, the process of heat transfer and heat transfer coefficient of a solar dryer with and without rotation of absorber plate was compared. Materials and Methods The experiments were conducted in Azarshahr, East Azarbayjan province, Iran in September 2014. Newton's law of thermodynamic was used to analyze the working condition of solar absorber. For this purpose the absorber plate was divided into four equal parts. According to the thermal equations and related boundary conditions as well as the relationship between heat transfer coefficient and the temperature gradient, equation 1 for the Nusselet number obtained: 1 Beside the relationship between Nusselt number and heat transfer coefficient is defined as equation 2: 2 Finally

  5. Visualization of Biosurfactant Film Flow in a Bacillus subtilis Swarm Colony on an Agar Plate.

    Science.gov (United States)

    Kim, Kyunghoon; Kim, Jung Kyung

    2015-08-26

    Collective bacterial dynamics plays a crucial role in colony development. Although many research groups have studied the behavior of fluidic swarm colonies, the detailed mechanics of its motion remains elusive. Here, we developed a visualization method using submicron fluorescent beads for investigating the flow field in a thin layer of fluid that covers a Bacillus subtilis swarm colony growing on an agar plate. The beads were initially embedded in the agar plate and subsequently distributed spontaneously at the upper surface of the expanding colony. We conducted long-term live cell imaging of the B. subtilis colony using the fluorescent tracers, and obtained high-resolution velocity maps of microscale vortices in the swarm colony using particle image velocimetry. A distinct periodic fluctuation in the average speed and vorticity of flow in swarm colony was observed at the inner region of the colony, and correlated with the switch between bacterial swarming and growth phases. At the advancing edge of the colony, both the magnitudes of velocity and vorticity of flow in swarm colony were inversely correlated with the spreading speed of the swarm edge. The advanced imaging tool developed in this study would facilitate further understanding of the effect of micro vortices in swarm colony on the collective dynamics of bacteria.

  6. Fluid flow and heat transfer of carbon nanotubes along a flat plate with Navier slip boundary

    Science.gov (United States)

    Khan, W. A.; Khan, Z. H.; Rahi, M.

    2014-06-01

    Homogeneous flow model is used to study the flow and heat transfer of carbon nanotubes (CNTs) along a flat plate subjected to Navier slip and uniform heat flux boundary conditions. This is the first paper on the flow and heat transfer of CNTs along a flat plate. Two types of CNTs, namely, single- and multi-wall CNTs are used with water, kerosene or engine oil as base fluids. The empirical correlations are used for the thermophysical properties of CNTs in terms of the solid volume fraction of CNTs. For the effective thermal conductivity of CNTs, Xue (Phys B Condens Matter 368:302-307, 2005) model has been used and the results are compared with the existing theoretical models. The governing partial differential equations and boundary conditions are converted into a set of nonlinear ordinary differential equations using suitable similarity transformations. These equations are solved numerically using a very efficient finite difference method with shooting scheme. The effects of the governing parameters on the dimensionless velocity, temperature, skin friction, and Nusselt numbers are investigated and presented in graphical and tabular forms. The numerical results of skin friction and Nusselt numbers are compared with the available data for special cases and are found in good agreement.

  7. Numerical Analysis of Flow Distribution in a Sodium Chamber of a Finned-tube Sodium-to-Air Heat Exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Youngchul; Son, Seokkwon; Kim, Hyungmo; Eoh, Jaehyuk; Jeong, Jiyoung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    DHR systems consist of two diverse heat removal loops such as passive and active DHR systems, and the heat load imposed on the primary sodium pool is safely rejected into the environment through different kinds of sodium-to-air heat exchangers, e.g. M-shape and helical-coil type air-coolers. The former is called as an FHX(Forced-draft sodium-to-air Heat Exchanger) and the latter is simply called as an AHX(natural-draft sodium-to-Air Heat Exchanger). In a general sodium-to-air heat exchanger design, convection resistance in a shell-side air flow path becomes dominant factor affecting the mechanism of conjugate heat transfer from the sodium flow inside the tube to the air path across the sodium tube wall. Hence verification of the flow and heat transfer characteristics is one of the most important tasks to demonstrate decay heat removal performance. To confirm a kind of ultimate heat sink heat exchanger, a medium-scale Sodium thermal-hydraulic Experiment Loop for Finned-tube sodium-to-Air Heat exchanger (here after called the SELFA) has been designed and is recently being constructed at KAERI site. The introduction of the flow baffle inside the upper sodium chamber of the model FHX unit in the SELFA facility is briefly proposed and discussed as well. The present study aims at introducing a flow baffle design inside the upper sodium chamber to make more equalized flowrates flowing into each heat transfer tube of the model FHX unit. In the cases without the flow baffle geometry, it was observed lager discrepancies in flowrates at the heat transfer tubes. However it was also found that those kinds of discrepancies could be definitely decreased at around 1/10 by employing a flow baffle.

  8. Flow Regimes of Air-Water Counterflow Through Cross Corrugated Parallel Plates

    Energy Technology Data Exchange (ETDEWEB)

    de Almeida, V.F.

    2000-06-07

    Heretofore unknown flow regimes of air-water counterflow through a pair of transparent vertical parallel cross corrugated plates were observed via high-speed video. Air flows upward driven by pressure gradient and water, downward driven by gravity. The crimp geometry of the corrugations was drawn from typical corrugated sheets used as filling material in modern structured packed towers. Four regimes were featured, namely, rivulet, bicontinuous, flooding fronts, and flooding waves. It is conceivable that the regimes observed might constitute the basis for understanding how gas and liquid phases contend for available space in the interstices of structured packings in packed towers. Flow regime transitions were expressed in terms of liquid load (liquid superficial velocity) and gas flow factor parameters commonly used in pressure drop and capacity curves. We have carefully examined the range of parameters equivalent to the ill-understood high-liquid-flow operation in packed towers. More importantly, our findings should prove valuable in validating improved first-principles modeling of gas-liquid flows in these industrially important devices.

  9. Mass-transfer characterization in a parallel-plate electrochemical reactor with convergent flow

    International Nuclear Information System (INIS)

    Colli, A.N.; Bisang, J.M.

    2013-01-01

    Highlights: • A convergent laminar flow enhances and becomes more uniform the mass-transfer rate. • The mass-transfer rate is increased under convergent turbulent flow conditions. • The mass-transfer rate under convergent laminar flow can be theoretically predicted. • A convergent duct improves the reactor behaviour and the concept is easily applicable. -- Abstract: A continuous reduction in the cross-section area is analysed as a means of improving mass-transfer in a parallel-plate electrochemical reactor. Experimental local mass-transfer coefficients along the electrode length are reported for different values of the convergent ratio and Reynolds numbers, using the reduction of ferricyanide as a test reaction. The Reynolds numbers evaluated at the reactor inlet range from 85 to 4600 with interelectrode gaps of 2 and 4 mm. The convergent flow improves the mean mass-transfer coefficient by 10–60% and mass-transfer distribution under laminar flow conditions becomes more uniform. The experimental data under laminar flow conditions are compared with theoretical calculations obtained by a computational fluid dynamics software and also with an analytical simplified model. A suitable agreement is observed between both theoretical treatments and with the experimental results. The pressure drop across the reactor is reported and compared with theoretical predictions

  10. Unsteady natural convection flow past an accelerated vertical plate in a thermally stratified fluid

    Directory of Open Access Journals (Sweden)

    Deka Rudra Kt.

    2009-01-01

    Full Text Available An exact solution to one-dimensional unsteady natural convection flow past an infinite vertical accelerated plate, immersed in a viscous thermally stratified fluid is investigated. Pressure work term and the vertical temperature advection are considered in the thermodynamic energy equation. The dimensionless governing equations are solved by Laplace Transform techniques for the Prandtl number unity. The velocity and temperature profiles as well as the skin-friction and the rate of heat transfer are presented graphically and discussed the effects of the Grashof number Gr, stratification parameter S at various times t.

  11. Magnetohydrodynamic flow of a rarefied gas near an accelerated porous plate

    International Nuclear Information System (INIS)

    Kant, R.

    1978-01-01

    An investigation is made of the flow of an electrically conducting rarefied gas due to the time-varying motion of an infinite porous plate, the gas being permeated by a transverse magnetic field. The suction is taken to be a constant and the magnetic lines of force are taken to be fixed relative to the fluid. The effects of magnetic field, rarefaction parameter, suction parameter are shown by means of some tables. The expressions of the skin friction for the two particular cases have also been obtained. (author)

  12. Conjugated heat transfer in laminar flow between parallel-plates channel

    International Nuclear Information System (INIS)

    Guedes, R.O.C.; Cotta, R.M.; Brum, N.C.L.

    1989-01-01

    An analysis is made of conjugated convective-conductive heat transfer in laminar flow of a newtonian fluid between parallel-plates channel, taking into account the longitudinal conduction along the duct walls only, by neglecting the transversal temperature gradients in the solid. This extended Graetz-type problem is then analytically handled through the generalized integral transform technique, providing accurate numerical results for quantities of practical interest sucyh as bulk and wall temperatures, and Nusselt numbers. The effects of a conjugation parameter and Biot number on heat transfer behavior are then investigated. (author)

  13. Viscous and Joule heating effects on MHD free convection flow with variable plate temperature

    International Nuclear Information System (INIS)

    Hossain, M.A.

    1990-09-01

    A steady two-dimensional laminar boundary layer flow of a viscous incompressible and electrically conducting fluid past a vertical heated plate with variable temperature in the presence of a transverse uniform magnetic field has been investigated by bringing the effect of viscous and Joules heating. The non-dimensional boundary layer equations are solved using the implicit finite difference method along with Newton's approximation for small Prandtl number chosen as typical of coolant liquid metals at operating temperature. (author). 10 refs, 2 figs, 1 tab

  14. Bifurcations and chaos of the nonlinear viscoelastic plates subjected to subsonic flow and external loads

    International Nuclear Information System (INIS)

    An, Fengxian; Chen, Fangqi

    2016-01-01

    Highlights: • The subharmonic bifurcations and chaotic motions are studied by means of Melnikov method. • The critical conditions for the occurrence of chaotic motions and subharmonic bifurcations are obtained. • The chaotic features on the system parameters are discussed. • The theoretical predictions are confirmed by numerical simulations. - Abstract: The subharmonic bifurcations and chaotic motions of the nonlinear viscoelastic plates subjected to subsonic flow and external loads are studied by means of Melnikov method. The critical conditions for the occurrence of chaotic motions are obtained. The chaotic features on the system parameters are discussed in detail. The conditions for subharmonic bifurcations are also obtained. For the system with no structural damping, chaotic motions can occur through infinite subharmonic bifurcations of odd orders. Furthermore, we confirm our theoretical predictions by numerical simulations. The theoretical results obtained here can help us to eliminate or suppress large nonlinear vibrations and chaotic motions of the nonlinear viscoelastic plates. Based on Melnikov method, complex dynamical behaviors of the nonlinear viscoelastic plates can be controlled by modifying the system parameters.

  15. The power flow angle of acoustic waves in thin piezoelectric plates.

    Science.gov (United States)

    Kuznetsova, Iren E; Zaitsev, Boris D; Teplykh, Andrei A; Joshi, Shrinivas G; Kuznetsova, Anastasia S

    2008-09-01

    The curves of slowness and power flow angle (PFA) of quasi-antisymmetric (A(0)) and quasi-symmetric (S(0)) Lamb waves as well as quasi-shear-horizontal (SH(0)) acoustic waves in thin plates of lithium niobate and potassium niobate of X-,Y-, and Z-cuts for various propagation directions and the influence of electrical shorting of one plate surface on these curves and PFA have been theoretically investigated. It has been found that the group velocity of such waves does not coincide with the phase velocity for the most directions of propagation. It has been also shown that S(0) and SH(0) wave are characterized by record high values of PFA and its change due to electrical shorting of the plate surface in comparison with surface and bulk acoustic waves in the same material. The most interesting results have been verified by experiment. As a whole, the results obtained may be useful for development of various devices for signal processing, for example, electrically controlled acoustic switchers.

  16. The use of multi-gap resistive plate chambers for in-beam PET in proton and carbon ion therapy

    CERN Document Server

    Watts, David; Sauli, Fabio; Amaldi, Ugo

    2013-01-01

    On-line verification of the delivered dose during proton and carbon ion radiotherapy is currently a very desirable goal for quality assurance of hadron therapy treatment plans. In-beam positron emission tomography (ibPET), which can provide an image of the β+ activity induced in the patient during irradiation, which in turn is correlated to the range of the ion beam, is one of the modalities for achieving this goal. Application to hadron therapy requires that the scanner geometry be modified from that which is used in nuclear medicine. In particular, PET detectors that allow a sub-nanosecond time-of-flight (TOF) registration of the collinear photons have been proposed. Inclusion of the TOF information in PET data leads to more effective PET sensitivity. Considering the challenges inherent in the ibPET technique, namely limited β+ activity and the effect of biological washout due to blood flow, TOF-PET technologies are very attractive. In this context, the TERA Foundation is investigating the use of resistiv...

  17. Energy flow in plate assembles by hierarchical version of finite element method

    DEFF Research Database (Denmark)

    Wachulec, Marcin; Kirkegaard, Poul Henning

    method has been proposed. In this paper a modified hierarchical version of finite element method is used for modelling of energy flow in plate assembles. The formulation includes description of in-plane forces so that planes lying in different planes can be modelled. Two examples considered are: L......The dynamic analysis of structures in medium and high frequencies are usually focused on frequency and spatial averages of energy of components, and not the displacement/velocity fields. This is especially true for structure-borne noise modelling. For the analysis of complicated structures...... the finite element method has been used to study the energy flow. The finite element method proved its usefulness despite the computational expense. Therefore studies have been conducted in order to simplify and reduce the computations required. Among others, the use of hierarchical version of finite element...

  18. The electrical MHD and Hall current impact on micropolar nanofluid flow between rotating parallel plates

    Science.gov (United States)

    Shah, Zahir; Islam, Saeed; Gul, Taza; Bonyah, Ebenezer; Altaf Khan, Muhammad

    2018-06-01

    The current research aims to examine the combined effect of magnetic and electric field on micropolar nanofluid between two parallel plates in a rotating system. The nanofluid flow between two parallel plates is taken under the influence of Hall current. The flow of micropolar nanofluid has been assumed in steady state. The rudimentary governing equations have been changed to a set of differential nonlinear and coupled equations using suitable similarity variables. An optimal approach has been used to acquire the solution of the modelled problems. The convergence of the method has been shown numerically. The impact of the Skin friction on velocity profile, Nusslet number on temperature profile and Sherwood number on concentration profile have been studied. The influences of the Hall currents, rotation, Brownian motion and thermophoresis analysis of micropolar nanofluid have been mainly focused in this work. Moreover, for comprehension the physical presentation of the embedded parameters that is, coupling parameter N1 , viscosity parameter Re , spin gradient viscosity parameter N2 , rotating parameter Kr , Micropolar fluid constant N3 , magnetic parameter M , Prandtl number Pr , Thermophoretic parameter Nt , Brownian motion parameter Nb , and Schmidt number Sc have been plotted and deliberated graphically.

  19. A Development of Technical Specification of a Research Reactor with Plate Fuels Cooled by Upward Flow

    International Nuclear Information System (INIS)

    Park, Sujin; Kim, Jeongeun; Kim, Hyeonil

    2016-01-01

    The contents of the TS(Technical Specifications) are definitions, safety limits, limiting safety system settings, limiting conditions for operation, surveillance requirements, design features, and administrative controls. TS for Nuclear Power Plants (NPPs) have been developed since many years until now. On the other hands, there are no applicable modernized references of TS for research reactors with many differences from NPPs in purpose and characteristics. Fuel temperature and Departure from Nuclear Boiling Ratio (DNBR) are being used as references from the thermal-hydraulic analysis point of view for determining whether the design of research reactors satisfies acceptance criteria for the nuclear safety or not. Especially for research reactors using plate-type fuels, fuel temperature and critical heat flux, however, are very difficult to measure during the reactor operation. This paper described the outline of main contents of a TS for open-pool research reactor with plate-type fuels using core cooling through passive systems, where acceptance criteria for nuclear safety such as CHF and fuel temperature cannot be directly measured, different from circumstances in NPPs. Thus, three independent variables instead of non-measurable acceptance criteria: fuel temperature and CHF are considered as safety limits, i.e., power, flow, and flow temperature

  20. Stress Linearization and Strength Evaluation of the BEP's Flow Plates for a Dual Cooled Fuel Assembly

    International Nuclear Information System (INIS)

    Kim, Jae Yong; Yoon, Kyung Ho; Kang, Heung Seok; Lee, Young Ho; Lee, Kang Hee; Kim, Hyung Kyu

    2009-01-01

    A fuel assembly is composed of 5 major components, such as a top end piece (TEP), a bottom end piece (BEP), spacer grids (SGs), guide tubes (GTs) and an instrumentation tube (IT) and fuel rods (FRs). There are no ASME criteria about all components except for a TEP/BEP. The TEP/BEP should satisfy stress intensity limits in case of condition A and B of ASME, Section III, Division 1 . Subsection NB. In a dual cooled fuel assembly, the array and position of fuels are changed from those of a conventional PWR fuel assembly to achieve a power uprating. The flow plates of top/bottom end pieces (TEP/BEP) have to be modified into proper shape to provide flow holes to direct the heated coolant into/out of the fuel assembly but structural intensity of these plates within a 22.241 kN axial loading should satisfy Tresca stress limits in ASME code. In this paper, stress linearization procedure and strength evaluation of a newly designed BEP for the dual cooled fuel assembly are described

  1. Large-scale performance studies of the Resistive Plate Chamber fast tracker for the ATLAS 1st-level muon trigger

    CERN Document Server

    Cattani, G; The ATLAS collaboration

    2009-01-01

    In the ATLAS experiment, Resistive Plate Chambers provide the first-level muon trigger and bunch crossing identification over large area of the barrel region, as well as being used as a very fast 2D tracker. To achieve these goals a system of about ~4000 gas gaps operating in avalanche mode was built (resulting in a total readout surface of about 16000 m2 segmented into 350000 strips) and is now fully operational in the ATLAS pit, where its functionality has been widely tested up to now using cosmic rays. Such a large scale system allows to study the performance of RPCs (both from the point of view of gas gaps and readout electronics) with unprecedented sensitivity to rare effects, as well as providing the means to correlate (in a statistically significant way) characteristics at production sites with performance during operation. Calibrating such a system means fine tuning thousands of parameters (involving both front-end electronics and gap voltage), as well as constantly monitoring performance and environm...

  2. High rate resistive plate chambers: An inexpensive, fast, large area detector of energetic charged particles for accelerator and non-accelerator applications

    International Nuclear Information System (INIS)

    Wuest, C.R.; Ables, E.; Bionta, R.M.; Clamp, O.; Haro, M.; Mauger, G.J.; Miller, K.; Olson, H.; Ramsey, P.

    1993-05-01

    Resistive Plate Chambers, or RPCs, have been used until recently as large detectors of cosmic ray muons. They are now finding use as fast large-area trigger and muon detection systems for different high energy physics detectors such the L3 Detector at LEP and future detectors to be built at the Superconducting Super Collider (SSC) and at the Large Hadron Collider (LHC) at CERN. RPC systems at these accelerators must operate with high efficiency, providing nanosecond timing resolution in particle fluences up to a few tens of kHz/cm 2 -- with thousands of square meters of active area. RPCs are simple and cheap to construct. The authors report here recent work on RPCs using new materials that exhibit a combination of desirable RPC features such as low bulk resistivity, high dielectric strength, low mass, and low cost. These new materials were originally developed for use in electronics assembly areas and other applications, where static electric charge buildup can damage sensitive electrical systems

  3. Countercurrent air/water and steam/water flow above a perforated plate. Report for October 1978-October 1979

    International Nuclear Information System (INIS)

    Hsieh, C.; Bankoff, S.G.; Tankin, R.S.; Yuen, M.C.

    1980-11-01

    The perforated plate weeping phenomena have been studied in both air/water and steam/cold water systems. The air/water experiment is designed to investigate the effect of geometric factors of the perforated plate on the rate of weeping. A new dimensionless flow rate in the form of H star is suggested. The data obtained are successfully correlated by this H star scaling in the conventional flooding equation. The steam/cold water experiment is concentrated on locating the boundary between weeping and no weeping. The effects of water subcooling, water inlet flow rate, and position of water spray are investigated. Depending on the combination of these factors, several types of weeping were observed. The data obtained at high water spray position can be related to the air/water flooding correlation by replacing the stream flow rate to an effective stream flow rate, which is determined by the mixing efficiency above the plate

  4. [Molecular imaging of thrombus with microbubbles targeted to alphavbeta3-integrin using an agarose flow chamber model].

    Science.gov (United States)

    Hu, Guang-quan; Liu, Jian; Yang, Li; Yan, Yi; Wu, Jue-fei; Xie, Jia-jia; Cai, Jing-jing; Ji, Li-jing; Bin, Jian-ping

    2010-03-01

    To assess the binding ability of microbubbles targeted to alphavbeta3-integrin (MBp) for thrombus-targeted contrast-enhanced ultrasound. Targeted microbubbles were prepared by conjugating the monoclonal antibody against alphavbeta3-integrin to lipid shell of the microbubble via the avidin-biotin bridges. Equivalent isotype control microbubbles (MB) or targeted ultrasound microbubbles (MBp) were randomly added into the flow chamber. After a 30-min incubation with the thrombus fixed in an agarose flow chamber model, the thrombus was washed with a continuous flow of PBS solution (15 cm/s) for 2, 4, 6, 8 and 10 min, followed by thrombus imaging using contrast-enhanced ultrasound and measurement of the video intensity (VI) values of the images. The VI of the thrombus in MBp group was reduced by 28%-66%, while that in control MB group was decreased by 87%-94%, and the VI values of the thrombus group were significantly greater in former group at each of the time points (Pevaluation of the thrombus-binding capability of the targeted microbubble (MBp) by simulating the shear stress in vivo can be helpful for predicting the in vivo effects of ultrasonic molecular imaging using MBp.

  5. The effect of plate thickness, surface tension and fluid flow on detachment of drops from a plate

    NARCIS (Netherlands)

    Lexmond, A.S.; Geld, van der C.W.M.; Celata, G.P.

    2004-01-01

    The pinch-off of drops from the downstream end of plates is an important re-entrainment mechanism of condensate in compact condensers. The present experimental study complements a previous one [1], in which ethanol and water drops were created for various mass densities and gas velocities at the

  6. A Prototype Flux-Plate Heat-Flow Sensor for Venus Surface Heat-Flow Determinations

    Science.gov (United States)

    Morgan, Paul; Reyes, Celso; Smrekar, Suzanne E.

    2005-01-01

    Venus is the most Earth-like planet in the Solar System in terms of size, and the densities of the two planets are almost identical when selfcompression of the two planets is taken into account. Venus is the closest planet to Earth, and the simplest interpretation of their similar densities is that their bulk compositions are almost identical. Models of the thermal evolution of Venus predict interior temperatures very similar to those indicated for the regions of Earth subject to solid-state convection, but even global analyses of the coarse Pioneer Venus elevation data suggest Venus does not lose heat by the same primary heat loss mechanism as Earth, i.e., seafloor spreading. The comparative paucity of impact craters on Venus has been interpreted as evidence for relatively recent resurfacing of the planet associated with widespread volcanic and tectonic activity. The difference in the gross tectonic styles of Venus and Earth, and the origins of some of the enigmatic volcano-tectonic features on Venus, such as the coronae, appear to be intrinsically related to Venus heat loss mechanism(s). An important parameter in understanding Venus geological evolution, therefore, is its present surface heat flow. Before the complications of survival in the hostile Venus surface environment were tackled, a prototype fluxplate heat-flow sensor was built and tested for use under synthetic stable terrestrial surface conditions. The design parameters for this prototype were that it should operate on a conforming (sand) surface, with a small, self-contained power and recording system, capable of operating without servicing for at least several days. The precision and accuracy of the system should be < 5 mW/sq m. Additional information is included in the original extended abstract.

  7. Mixed convection boundary layer flow over a moving vertical flat plate in an external fluid flow with viscous dissipation effect.

    Directory of Open Access Journals (Sweden)

    Norfifah Bachok

    Full Text Available The steady boundary layer flow of a viscous and incompressible fluid over a moving vertical flat plate in an external moving fluid with viscous dissipation is theoretically investigated. Using appropriate similarity variables, the governing system of partial differential equations is transformed into a system of ordinary (similarity differential equations, which is then solved numerically using a Maple software. Results for the skin friction or shear stress coefficient, local Nusselt number, velocity and temperature profiles are presented for different values of the governing parameters. It is found that the set of the similarity equations has unique solutions, dual solutions or no solutions, depending on the values of the mixed convection parameter, the velocity ratio parameter and the Eckert number. The Eckert number significantly affects the surface shear stress as well as the heat transfer rate at the surface.

  8. Water flow experiments and analyses on the cross-flow type mercury target model with the flow guide plates

    CERN Document Server

    Haga, K; Kaminaga, M; Hino, R

    2001-01-01

    A mercury target is used in the spallation neutron source driven by a high-intensity proton accelerator. In this study, the effectiveness of the cross-flow type mercury target structure was evaluated experimentally and analytically. Prior to the experiment, the mercury flow field and the temperature distribution in the target container were analyzed assuming a proton beam energy and power of 1.5 GeV and 5 MW, respectively, and the feasibility of the cross-flow type target was evaluated. Then the average water flow velocity field in the target mock-up model, which was fabricated from Plexiglass for a water experiment, was measured at room temperature using the PIV technique. Water flow analyses were conducted and the analytical results were compared with the experimental results. The experimental results showed that the cross-flow could be realized in most of the proton beam path area and the analytical result of the water flow velocity field showed good correspondence to the experimental results in the case w...

  9. Flow of supersonic jets across flat plates: Implications for ground-level flow from volcanic blasts

    Science.gov (United States)

    Orescanin, Mara M.; Prisco, David; Austin, Joanna M.; Kieffer, Susan W.

    2014-04-01

    We report on laboratory experiments examining the interaction of a jet from an overpressurized reservoir with a canonical ground surface to simulate lateral blasts at volcanoes such as the 1980 blast at Mount St. Helens. These benchmark experiments test the application of supersonic jet models to simulate the flow of volcanic jets over a lateral topography. The internal shock structure of the free jet is modified such that the Mach disk shock is elevated above the surface. In elevation view, the width of the shock is reduced in comparison with a free jet, while in map view the dimensions are comparable. The distance of the Mach disk shock from the vent is in good agreement with free jet data and can be predicted with existing theory. The internal shock structures can interact with and penetrate the boundary layer. In the shock-boundary layer interaction, an oblique shock foot is present in the schlieren images and a distinctive ground signature is evident in surface measurements. The location of the oblique shock foot and the surface demarcation are closely correlated with the Mach disk shock location during reservoir depletion, and therefore, estimates of a ground signature in a zone devastated by a blast can be based on the calculated shock location from free jet theory. These experiments, combined with scaling arguments, suggest that the imprint of the Mach disk shock on the ground should be within the range of 4-9 km at Mount St. Helens depending on assumed reservoir pressure and vent dimensions.

  10. The flow of a non-Newtonian fluid induced due to the oscillations of a porous plate

    Directory of Open Access Journals (Sweden)

    S. Asghar

    2004-01-01

    Full Text Available An analytic solution of the flow of a third-grade fluid on a porous plate is constructed. The porous plate is executing oscillations in its own plane with superimposed injection or suction. An increasing or decreasing velocity amplitude of the oscillating porous plate is also examined. It is also shown that in case of third-grade fluid, a combination of suction/injection and decreasing/increasing velocity amplitude is possible as well. Several limiting situations with their implications are given and discussed.

  11. Hall effects on unsteady MHD reactive flow of second grade fluid through porous medium in a rotating parallel plate channel

    Science.gov (United States)

    Krishna, M. Veera; Swarnalathamma, B. V.

    2017-07-01

    We considered the transient MHD flow of a reactive second grade fluid through porous medium between two infinitely long horizontal parallel plates when one of the plate is set into uniform accelerated motion in the presence of a uniform transverse magnetic field under Arrhenius reaction rate. The governing equations are solved by Laplace transform technique. The effects of the pertinent parameters on the velocity, temperature are discussed in detail. The shear stress and Nusselt number at the plates are also obtained analytically and computationally discussed with reference to governing parameters.

  12. Titer plate formatted continuous flow thermal reactors for high throughput applications: fabrication and testing

    International Nuclear Information System (INIS)

    Park, Daniel Sang-Won; Chen, Pin-Chuan; You, Byoung Hee; Kim, Namwon; Park, Taehyun; Lee, Tae Yoon; Soper, Steven A; Nikitopoulos, Dimitris E; Murphy, Michael C; Datta, Proyag; Desta, Yohannes

    2010-01-01

    A high throughput, multi-well (96) polymerase chain reaction (PCR) platform, based on a continuous flow (CF) mode of operation, was developed. Each CFPCR device was confined to a footprint of 8 × 8 mm 2 , matching the footprint of a well on a standard micro-titer plate. While several CFPCR devices have been demonstrated, this is the first example of a high-throughput multi-well continuous flow thermal reactor configuration. Verification of the feasibility of the multi-well CFPCR device was carried out at each stage of development from manufacturing to demonstrating sample amplification. The multi-well CFPCR devices were fabricated by micro-replication in polymers, polycarbonate to accommodate the peak temperatures during thermal cycling in this case, using double-sided hot embossing. One side of the substrate contained the thermal reactors and the opposite side was patterned with structures to enhance thermal isolation of the closely packed constant temperature zones. A 99 bp target from a λ-DNA template was successfully amplified in a prototype multi-well CFPCR device with a total reaction time as low as ∼5 min at a flow velocity of 3 mm s −1 (15.3 s cycle −1 ) and a relatively low amplification efficiency compared to a bench-top thermal cycler for a 20-cycle device; reducing the flow velocity to 1 mm s −1 (46.2 s cycle −1 ) gave a seven-fold improvement in amplification efficiency. Amplification efficiencies increased at all flow velocities for 25-cycle devices with the same configuration.

  13. Flow Phenomena in the Very Near Wake of a Flat Plate with a Circular Trailing Edge

    Science.gov (United States)

    Rai, Man Mohan

    2014-01-01

    The very near wake of a flat plate with a circular trailing edge, exhibiting pronounced shedding of wake vortices, is investigated with data from a direct numerical simulation. The separating boundary layers are turbulent and statistically identical thus resulting in a wake that is symmetric in the mean. The focus here is on the instability of the detached shear layers, the evolution of rib-vortex induced localized regions of reverse flow that detach from the main body of reverse flow in the trailing edge region and convect downstream, and phaseaveraged velocity statistics in the very near wake. The detached shear layers are found to exhibit unstable behavior intermittently, including the development of shear layer vortices as in earlier cylinder flow investigations with laminar separating boundary layers. Only a small fraction of the separated turbulent boundary layers undergo this instability, and form the initial shed vortices. Pressure spectra within the shear layers show a broadband peak at a multiple of shedding frequency. Phase-averaged intensity and shear stress distributions of the randomly fluctuating component of velocity are compared with those obtained in the near wake. The distributions of the production terms in the transport equations for the turbulent stresses are also provided.

  14. Mixed convection between horizontal plates and consequences for chemical vapor deposition flows

    International Nuclear Information System (INIS)

    Chiu, K.C.

    1986-01-01

    To simulate the fluid dynamics of VD systems, mixed convection between horizontal plates (AR = width/height = 10) heated from below was studied by laser Doppler anemometry in a range 1368 < Ra < 8300 and 15 < R3 < 170. The entrance effects were characterized by two lengths: one for the onset of bouyancy-driven instability, and one for the full development of longitudinal convection rolls. Explicit expressions for both entrance lengths are given in terms of Ra and Re. In addition, unsteady longitudinal convection rolls were observed. These are discussed in terms of the admixture of transverse convection rolls and/or contributions from upstream turbulence. For the fully developed region it is shown analytically that the transverse velocities of the longitudinal convection rolls, v and w, are independent of the forced flow and are identical to those of the two-dimensional Rayleigh-Benard convection rolls. These fundamental results serve as a base for the discussion of horizontal CVD flows. The entrance and sidewall effects are found to have pronounced influences on the flow patterns observed in CVD (AR = 2) reactors

  15. Hydromagnetic flow and radiative heat transfer of nanofluid past a vertical plate

    Directory of Open Access Journals (Sweden)

    B. Ganga

    2017-11-01

    Full Text Available Hydromagnetic flow of an incompressible viscous nanofluid past a vertical plate in the presence of thermal radiation is investigated both analytically and numerically. The radiative heat flux is described by the Rosseland diffusion approximation in the energy equation. The governing non-linear partial differential equations are converted into a set of ordinary differential equations by suitable similarity transformations. The resulting ordinary differential equations are successfully solved analytically with the help of homotopy analysis method and numerically by the fourth order Runge–Kutta method with shooting technique. The effects of various physical parameters are analyzed and discussed in graphical and tabular forms. The effects of some physical parameters such as Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, radiation parameter and magnetic parameter are analyzed on the velocity, temperature and solid volume fraction profiles as well as on the reduced Nusselt number and the local Sherwood number. An excellent agreement is observed between present analytical and numerical results. Keywords: Nanofluid, Hydromagnetic, Homotopy analysis method, Vertical plate and thermal radiation

  16. Transient heat transfer to laminar flow from a flat plate with heat capacity

    International Nuclear Information System (INIS)

    Hanawa, Juichi

    1975-01-01

    As the most basic problem in transient heat transfer, a plate with heat capacity was studied, which is placed in uniform laminar flow in parallel with it, is initially at the same temperature as that of the fluid, and then abruptly is given a specific heating value. The equation of transient heat transfer in this case was solved by numerical calculation. The following matters were revealed. (1) The equation was able to be solved by the application of Laplace transformation and numerical inverse transformation. (2) Wall temperature when the heat capacity of a plate was zero initially agreed well with heat conduction solution. With increase of the heat capacity, the delay in wall temperature rise was increased. (3) Heat transfer rate in case of the heat capacity of zero initially agreed well with the heat-conduction solution. With increase of the heat capacity, the Nusselt number increased. (4) Temperature distribution in case of the heat capacity of zero initially agreed well with the heat-conduction solution. (Mori, K.)

  17. Characteristics of heat transfer and fluid flow in a channel with single-row plates array oblique to flow direction for photovoltaic/thermal system

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Ahmed Hamza H. [Department of Energy Resources and Environmental Engineering, Egypt-Japan University of Science and Technology (E-JUST), P.O. Box 179, New Borg El-Arab City, Alexandria 21934 (Egypt); Ahmed, Mahmoud; Youssef, M.S. [Department of Mechanical Engineering, Faculty of Engineering, Assiut University, Assiut 71516 (Egypt)

    2010-09-15

    This study has been carried out to investigate the characteristics of convective heat transfer and fluid flow for a single row of oblique plates array to the flow direction inside a channel. The flow inside the channel is laminar and the plates array have spanwise distance between the plates and heated by radiation. This configuration has been designed to be used for Photovoltaic/Thermal system (PV/T) applications. The theoretical results are validated with measured values, and a good agreement prevailed. The results show that an increase in the plate oblique angle ({gamma}) in the range from 0 to 15 degrees, leads to an increase in the Nusselt number (Nu) up to a maximum value and then decreases. The oblique angle at the maximum value of Nu depends on the flow Reynolds Number (Re), and (l{sub w}/l{sub pl}), where (l{sub w}/l{sub pl}) is defined as the ratio of the plates' spacing at zero oblique angle to the plate length. Furthermore, increasing (l{sub w}/l{sub pl}) results in a significant increase in the heat transfer coefficient depending on the values of Re, and plate oblique angle ({gamma}). In addition, increasing ({gamma}) from 0 to 15 degrees results in a decrease in the friction factor up to a certain value, after which the friction value approaches a constant value depending on Re value and (l{sub w}/l{sub pl}). It was found that for any value of the plate oblique angle ({gamma}), the friction factor decreases with the increase of the values of (l{sub w}/l{sub pl}) and Re, respectively. (author)

  18. Characteristics of heat transfer and fluid flow in a channel with single-row plates array oblique to flow direction for photovoltaic/thermal system

    International Nuclear Information System (INIS)

    Ali, Ahmed Hamza H.; Ahmed, Mahmoud; Youssef, M.S.

    2010-01-01

    This study has been carried out to investigate the characteristics of convective heat transfer and fluid flow for a single row of oblique plates array to the flow direction inside a channel. The flow inside the channel is laminar and the plates array have spanwise distance between the plates and heated by radiation. This configuration has been designed to be used for Photovoltaic/Thermal system (PV/T) applications. The theoretical results are validated with measured values, and a good agreement prevailed. The results show that an increase in the plate oblique angle (γ) in the range from 0 to 15 degrees, leads to an increase in the Nusselt number (Nu) up to a maximum value and then decreases. The oblique angle at the maximum value of Nu depends on the flow Reynolds Number (Re), and (l w /l pl ), where (l w /l pl ) is defined as the ratio of the plates' spacing at zero oblique angle to the plate length. Furthermore, increasing (l w /l pl ) results in a significant increase in the heat transfer coefficient depending on the values of Re, and plate oblique angle (γ). In addition, increasing (γ) from 0 to 15 degrees results in a decrease in the friction factor up to a certain value, after which the friction value approaches a constant value depending on Re value and (l w /l pl ). It was found that for any value of the plate oblique angle (γ), the friction factor decreases with the increase of the values of (l w /l pl ) and Re, respectively.

  19. Control of supersonic axisymmetric base flows using passive splitter plates and pulsed plasma actuators

    Science.gov (United States)

    Reedy, Todd Mitchell

    An experimental investigation evaluating the effects of flow control on the near-wake downstream of a blunt-based axisymmetric body in supersonic flow has been conducted. To better understand and control the physical phenomena that govern these massively separated high-speed flows, this research examined both passive and active flow-control methodologies designed to alter the stability characteristics and structure of the near-wake. The passive control investigation consisted of inserting splitter plates into the recirculation region. The active control technique utilized energy deposition from multiple electric-arc plasma discharges placed around the base. The flow-control authority of both methodologies was evaluated with experimental diagnostics including particle image velocimetry, schlieren photography, surface flow visualization, pressure-sensitive paint, and discrete surface pressure measurements. Using a blowdown-type wind tunnel reconstructed specifically for these studies, baseline axisymmetric experiments without control were conducted for a nominal approach Mach number of 2.5. In addition to traditional base pressure measurements, mean velocity and turbulence quantities were acquired using two-component, planar particle image velocimetry. As a result, substantial insight was gained regarding the time-averaged and instantaneous near-wake flow fields. This dataset will supplement the previous benchmark point-wise laser Doppler velocimetry data of Herrin and Dutton (1994) for comparison with new computational predictive techniques. Next, experiments were conducted to study the effects of passive triangular splitter plates placed in the recirculation region behind a blunt-based axisymmetric body. By dividing the near-wake into 1/2, 1/3, and 1/4 cylindrical regions, the time-averaged base pressure distribution, time-series pressure fluctuations, and presumably the stability characteristics were altered. While the spatial base pressure distribution was

  20. Acoustically Generated Flows in Flexural Plate Wave Sensors: a Multifield Analysis

    Science.gov (United States)

    Sayar, Ersin; Farouk, Bakhtier

    2011-11-01

    Acoustically excited flows in a microchannel flexural plate wave device are explored numerically with a coupled solid-fluid mechanics model. The device can be exploited to integrate micropumps with microfluidic chips. A comprehensive understanding of the device requires the development of coupled two or three-dimensional fluid structure interactive (FSI) models. The channel walls are composed of layers of ZnO, Si3N4 and Al. An isothermal equation of state for the fluid (water) is employed. The flexural motions of the channel walls and the resulting flowfields are solved simultaneously. A parametric analysis is performed by varying the values of the driving frequency, voltage of the electrical signal and the channel height. The time averaged axial velocity is found to be proportional to the square of the wave amplitude. The present approach is superior to the method of successive approximations where the solid-liquid coupling is weak.

  1. Application of Fourier transform to MHD flow over an accelerated plate with partial-slippage

    Directory of Open Access Journals (Sweden)

    Salman Ahmad

    2014-06-01

    Full Text Available Magneto-Hydrodynamic (MHD flow over an accelerated plate is investigated with partial slip conditions. Generalized Fourier Transform is used to get the exact solution not only for uniform acceleration but also for variable acceleration. The numerical solution is obtained by using linear finite element method in space and One-Step-θ-scheme in time. The resulting discretized algebraic systems are solved by applying geometric-multigrid approach. Numerical solutions are compared with the obtained Fourier transform results. Many interesting results related with slippage and MHD effects are discussed in detail through graphical sketches and tables. Application of Dirac-Delta function is one of the main features of present work.

  2. Natural convective flow of a magneto-micropolar fluid along a vertical plate

    Directory of Open Access Journals (Sweden)

    M. Ferdows

    2018-03-01

    Full Text Available This paper presents a numerical study of natural convective flow of an electrically conducting viscous micropolar fluid past a vertical plate. Internal heat generation (IHG versus without IHG in the medium are discussed in the context of corresponding similarity solutions. Results are presented in terms of velocity, angular velocity, temperature, skin friction in tabular forms, local wall-coupled stress, and Nusselt number. Computations have been accomplished by parametrizing the micropolar, micro-rotation, magnetic field, suction parameters, and the Prandtl number. Several critical issues are addressed at the end of the paper with reference to a previous study by El-Hakiem. The study is relevant to high-temperature electromagnetic materials fabrication systems. Keywords: Natural convection, Thermal boundary layer, Micropolar fluid, Similarity transformation, Internal heat generation

  3. Analytical investigation of third grade nanofluidic flow over a riga plate using Cattaneo-Christov model

    Science.gov (United States)

    Naseem, Anum; Shafiq, Anum; Zhao, Lifeng; Farooq, M. U.

    2018-06-01

    This article addresses third grade nanofluidic flow instigated by riga plate and Cattaneo-Christov theory is adopted to investigate thermal and mass diffusions with the incorporation of newly eminent zero nanoparticles mass flux condition. The governing system of equations is nondimensionalized through relevant similarity transformations and significatory findings are attained by using optimal homotopy analysis method. The behaviors of affecting parameters for velocity, temperature and concentration profiles are depicted graphically and also verified through three dimensional patterns for some parameters. Values of skin friction coefficient and Nusselt number with the apposite discussion have been recorded. The current results reveal that temperature and concentration profiles experience decline when thermal and concentration relaxation parameters are augmented respectively.

  4. Parallel DSMC Solution of Three-Dimensional Flow Over a Finite Flat Plate

    Science.gov (United States)

    Nance, Robert P.; Wilmoth, Richard G.; Moon, Bongki; Hassan, H. A.; Saltz, Joel

    1994-01-01

    This paper describes a parallel implementation of the direct simulation Monte Carlo (DSMC) method. Runtime library support is used for scheduling and execution of communication between nodes, and domain decomposition is performed dynamically to maintain a good load balance. Performance tests are conducted using the code to evaluate various remapping and remapping-interval policies, and it is shown that a one-dimensional chain-partitioning method works best for the problems considered. The parallel code is then used to simulate the Mach 20 nitrogen flow over a finite-thickness flat plate. It is shown that the parallel algorithm produces results which compare well with experimental data. Moreover, it yields significantly faster execution times than the scalar code, as well as very good load-balance characteristics.

  5. Boundary Layer Flow and Heat Transfer of FMWCNT/Water Nanofluids over a Flat Plate

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Safaei

    2016-09-01

    Full Text Available In the present study, the heat transfer and flow of water/FMWCNT (functionalized multi-walled carbon nanotube nanofluids over a flat plate was investigated using a finite volume method. Simulations were performed for velocity ranging from 0.17 mm/s to 1.7 mm/s under laminar regime and nanotube concentrations up to 0.2%. The 2-D governing equations were solved using an in-house FORTRAN code. For a specific free stream velocity, the presented results showed that increasing the weight percentage of nanotubes increased the Nusselt number. However, an increase in the solid weight percentage had a negligible effect on the wall shear stress. The results also indicated that increasing the free stream velocity for all cases leads to thinner boundary layer thickness, while increasing the FMWCNT concentration causes an increase in the boundary layer thickness.

  6. Homogeneous and Stratified Liquid-Liquid Flow Effect of a Viscosity Reducer: I. Comparison in parallel plates for heavy crude

    Directory of Open Access Journals (Sweden)

    E. J. Suarez-Dominguez

    2016-12-01

    Full Text Available Production of heavy crude oil in Mexico, and worldwide, is increasing which has led to the application of different methods to reduce viscosity or to enhance transport through stratified flow to continue using the existing infrastructures. In this context, injecting a viscosity improver that does not mix completely with the crude, establishes a liquid-liquid stratified flow. On the basis of a parallel plates model, comparing the increase of flow that occurs in the one-phase case which assumes a complete mixture between the crude and the viscosity improver against another stratified liquid-liquid (no mixing between the oil and compared improver; it was found that in both cases there is a flow increase for the same pressure drop with a maximum for the case in which the flow improver is between the plates and the crude.

  7. Improvements in ionization chambers

    International Nuclear Information System (INIS)

    Whetten, N.R.; Zubal, C.

    1980-01-01

    A method of reducing mechanical vibrations transmitted to the parallel plate electrodes of ionization chamber x-ray detectors, commonly used in computerized x-ray axial tomography systems, is described. The metal plate cathodes and anodes are mounted in the ionizable gas on dielectric sheet insulators consisting of a composite of silicone resin and glass fibres. (UK)

  8. Calculation of the heat flow peak in case of local defect of the fuel plate of a nuclear reactor

    International Nuclear Information System (INIS)

    Fabrega, Serge

    1965-11-01

    The author reports the calculation of the local thermal flow which exits a fuel plate in a nuclear reactor, where a fabrication defect creates a much localized peak of the power density released in the plate. He first reports the development of the problem equations: hypotheses and data, equation elaboration, simplification and resolution. He presents the results of a numeric application to actual cases, and describes how the conduction in the sheath is taken into account (study of the influence of peak width and shape), and gives a synthetic presentation of the formula for the approximate calculation of the heat flow in case of local defect [fr

  9. Design of experiment study of the parameters that affect performance of three flow plate configurations of a proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Carton, J.G.; Olabi, A.G.

    2010-01-01

    Low temperature hydrogen fuel cells are electrochemical devices which offer a promising alternative to traditional power sources. Fuel cells produce electricity with a reaction of the fuel (hydrogen) and air. Fuel cells have the advantage of being clean; only producing water and heat as by products. The efficiency of a fuel cell varies depending on the type; SOFC with CHP for example, can have a system efficiency of up to 65%. What the Authors present here is a comparison between three different configurations of flow plates of a proton exchange membrane fuel cell, the manufacturer's serpentine flow plate and two new configurations; the maze flow plate and the parallel flow plate. A study of the input parameters affecting output responses of voltage, current, power and efficiency of a fuel cell is performed through experimentation. The results were taken from direct readings of the fuel cell and from polarisation curves produced. This information was then analysed through a design of experiment to investigate the effects of the changing parameters on different configurations of the fuel cell's flow plates. The results indicate that, in relation to current and voltage response of the polarisation curve and the corresponding graphs produced from the DOE, the serpentine flow plate design is a much more effective design than the maze or parallel flow plate design. It was noted that the parallel flow plate performed reasonably well at higher pressures but over all statically the serpentine flow plate performed better.

  10. Theoretical and experimental investigation of wickless heat pipes flat plate solar collector with cross flow heat exchanger

    International Nuclear Information System (INIS)

    Hussein, H.M.S.

    2007-01-01

    In this work, a wickless heat pipes flat plate solar collector with a cross flow heat exchanger was investigated theoretically and experimentally under the meteorological conditions of Cairo, Egypt. The author's earlier simulation program of wickless heat pipes flat plate solar water heaters was modified to be valid for the present type of wickless heat pipes solar collector by including the solution of the dimensionless governing equations of the present analysis. For verifying the modified simulation program, a wickless heat pipes flat plate solar collector with a cross flow heat exchanger was designed, constructed, and tested at different meteorological conditions and operating parameters. These parameters include different cooling water mass flow rates and different inlet cooling water temperatures. The comparison between the experimental results and their corresponding simulated ones showed considerable agreement. Under different climatic conditions, the experimental and theoretical results showed that the optimal mass flow rate is very close to the ASHRAE standard mass flow rate for testing conventional flat plate solar collectors. Also, the experimental and theoretical results indicated that the number of wickless heat pipes has a significant effect on the collector efficiency

  11. Peak nasal inspiratory flow as outcome for provocation studies in allergen exposure chambers

    DEFF Research Database (Denmark)

    Boelke, Georg; Berger, Uwe; Bergmann, Karl-Christian

    2017-01-01

    : In a randomized controlled blinded setting subjects suffering from allergic rhinitis were exposed to grass pollen, birch pollen, house dust mite and/or placebo in the GA(2)LEN chamber. Different allergen concentrations were used to evaluate symptom severities. Patients had to perform PNIF before and every 30 min...... during a challenge using a portable PNIF meter. RESULTS: 86 subjects participated in 203 challenges, altogether. House dust mite provocations caused the greatest reduction in PNIF values, followed by grass pollen and birch pollen. Provocations with every allergen or pollen concentration led...... symptoms. CONCLUSION: PNIF is a helpful and feasible tool for conducting provocation trials with allergens, especially grass pollen and house dust mite, in an AEC....

  12. Numerical investigation of the effects of compressibility on the flutter of a cantilevered plate in an inviscid, subsonic, open flow

    Science.gov (United States)

    Colera, Manuel; Pérez-Saborid, Miguel

    2018-06-01

    We have carried out a numerical study of the influence of the upstream Mach number on the flutter of a two-dimensional, cantilevered, flexible plate subject to a subsonic, inviscid, open flow. We have assumed a linear elastic model for the plate and that the fluid flow is governed by the linearized potential theory. The fluid equations are solved with a novel frequency-domain, finite differences method to obtain the generalized aerodynamic forces as a function of the plate displacements. Then, these generalized forces are coupled to the equation of motion of the plate and an eigenvalue analysis is performed to find the flutter point. The obtained results are in good agreement with those of related theoretical and experimental studies found in the literature. To the best of our knowledge, the analysis performed here is the first self-consistent, parametric study of the influence of the compressibility on the flutter point of a two-dimensional cantilevered plate in subsonic flow.

  13. The combined effects of wall longitudinal heat conduction and inlet fluid flow maldistribution in crossflow plate-fin heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Ranganayakulu, C. [Aeronautical Development Agency, Bangalore (India); Seetharamu, K.N. [School of Mechanical Engineering, Univ. of Southern Malaysia (KCP), Tronoh (Malaysia)

    2000-05-01

    An analysis of a crossflow plate-fin compact heat exchanger, accounting for the combined effect of two-dimensional longitudinal heat conduction through the exchanger wall and nonuniform inlet fluid flow distribution on both hot and cold fluid sides is carried out using a finite element method. Using the fluid flow maldistribution models, the exchanger effectiveness and its deterioration due to the combined effects of longitudinal heat conduction and flow nonuniformity are calculated for various design and operating conditions of the exchanger. It was found that the performance deteriorations are quite significant in some typical applications due to the combined effects of wall longitudinal heat conduction and inlet fluid flow nonuniformity on crossflow plate-fin heat exchanger. (orig.)

  14. Rotation and Radiation Effects on MHD Flow through Porous Medium Past a Vertical Plate with Heat and Mass Transfer

    Directory of Open Access Journals (Sweden)

    Uday Singh Rajput

    2017-11-01

    Full Text Available Effects of rotation and radiation on unsteady MHD flow past a vertical plate with variable wall temperature and mass diffusion in the presence of Hall current is studied here. Earlier we studied chemical reaction effect on unsteady MHD flow past an exponentially accelerated inclined plate with variable temperature and mass diffusion in the presence of Hall current. We had obtained the results which were in agreement with the desired flow phenomenon. To study further, we are changing the model by considering radiation effect on fluid, and changing the geometry of the model. Here in this paper we are taking the plate positioned vertically upward and rotating with velocity Ω . Further, medium of the flow is taken as porous. The plate temperature and the concentration level near the plate increase linearly with time. The governing system of partial differential equations is transformed to dimensionless equations using dimensionless variables. The dimensionless equations under consideration have been solved by Laplace transform technique. The model contains equations of motion, diffusion equation and equation of energy. To analyze the solution of the model, desirable sets of the values of the parameters have been considered. The governing equations involved in the flow model are solved by the Laplace-transform technique. The results obtained have been analyzed with the help of graphs drawn for different parameters. The numerical values obtained for the drag at boundary and Nusselt number have been tabulated. We found that the values obtained for velocity, concentration and temperature are in concurrence with the actual flow of the fluid

  15. Natural convection enhancement by a discrete vibrating plate and a cross-flow opening: a numerical investigation

    Science.gov (United States)

    Florio, L. A.; Harnoy, A.

    2011-06-01

    In this study, a unique combination of a vibrating plate and a cross-flow passage is proposed as a means of enhancing natural convection cooling. The enhancement potential was estimated based on numerical studies involving a representative model which includes a short, transversely oscillating plate, placed over a transverse cross-flow opening in a uniformly heated vertical channel wall dividing two adjacent vertical channels. The resulting velocity and temperature fields are analyzed, with the focus on the local thermal effects near the opening. The simulation indicates up to a 50% enhancement in the local heat transfer coefficient for vibrating plate amplitudes of at least 30% of the mean clearance space and frequencies of over 82 rad/s.

  16. DNS of heat transfer in transitional, accelerated boundary layer flow over a flat plate affected by free-stream fluctuations

    International Nuclear Information System (INIS)

    Wissink, Jan G.; Rodi, Wolfgang

    2009-01-01

    Direct numerical simulations (DNS) of flow over and heat transfer from a flat plate affected by free-stream fluctuations were performed. A contoured upper wall was employed to generate a favourable streamwise pressure gradient along a large portion of the flat plate. The free-stream fluctuations originated from a separate LES of isotropic turbulence in a box. In the laminar portions of the accelerating boundary layer flow the formation of streaks was observed to induce an increase in heat transfer by the exchange of hot fluid near the surface of the plate and cold fluid from the free-stream. In the regions where the streamwise pressure gradient was only mildly favourable, intermittent turbulent spots were detected which relaminarised downstream as the streamwise pressure gradient became stronger. The relaminarisation of the turbulent spots was reflected by a slight decrease in the friction coefficient, which converged to its laminar value in the region where the streamwise pressure gradient was strongest.

  17. Numerical Study on Turbulent Flow Inside a Channel with an Extended Chamber

    International Nuclear Information System (INIS)

    Lee, Young Tae; Lim, Hee Chang

    2010-01-01

    The paper describes a Large Eddy Simulation (LES) study of turbulent flow around a cavity. A series of three-dimensional cavities placed in a turbulent boundary layer are simulated at a Reynolds number of 1.0 x 10 5 by considering U and h, which represent the velocity at the top and the depth of the cavity, respectively. In order to obtain the appropriate solution for the filtered Navier-Stokes equation for incompressible flow, the computational mesh forms dense close to the wall of the cavity but relatively coarse away from the wall; this helps reduce computation cost and ensure rapid convergence. The Boussinesq hypothesis is employed in the subgrid-scale turbulence model. In order to determine the subgrid-scale turbulent viscosity, the Smagorinsky-Lilly SGS model is applied and the CFL number for time marching is set as 1.0. The results show the flow variations inside cavities of different sizes and shapes

  18. Experimental and Numerical Evaluation of the By-Pass Flow in a Catalytic Plate Reactor for Hydrogen Production

    DEFF Research Database (Denmark)

    Sigurdsson, Haftor Örn; Kær, Søren Knudsen

    2011-01-01

    Numerical and experimental study is performed to evaluate the reactant by-pass flow in a catalytic plate reactor with a coated wire mesh catalyst for steam reforming of methane for hydrogen generation. By-pass of unconverted methane is evaluated under different wire mesh catalyst width to reactor...

  19. Cold plate

    Energy Technology Data Exchange (ETDEWEB)

    Marroquin, Christopher M.; O' Connell, Kevin M.; Schultz, Mark D.; Tian, Shurong

    2018-02-13

    A cold plate, an electronic assembly including a cold plate, and a method for forming a cold plate are provided. The cold plate includes an interface plate and an opposing plate that form a plenum. The cold plate includes a plurality of active areas arranged for alignment over respective heat generating portions of an electronic assembly, and non-active areas between the active areas. A cooling fluid flows through the plenum. The plenum, at the non-active areas, has a reduced width and/or reduced height relative to the plenum at the active areas. The reduced width and/or height of the plenum, and exterior dimensions of cold plate, at the non-active areas allow the non-active areas to flex to accommodate surface variations of the electronics assembly. The reduced width and/or height non-active areas can be specifically shaped to fit between physical features of the electronics assembly.

  20. Heat transfer effects on a viscous dissipative fluid flow past a vertical plate in the presence of induced magnetic field

    Directory of Open Access Journals (Sweden)

    M.C. Raju

    2015-03-01

    Full Text Available A theoretical analysis is performed to study induced magnetic field effects on free convection flow past a vertical plate. The x¯-axis is taken vertically upwards along the plate, y¯-axis normal to the plate into the fluid region. It is assumed that the plate is electrically non-conducting and the applied magnetic field is of uniform strength (H0 and perpendicular to the plate. The magnetic Reynolds number of the flow is not taken to be small enough so that the induced magnetic field is taken into account. The coupled nonlinear partial differential equations are solved by Perturbation technique and the effects of various physical parameters on velocity, temperature, and induced magnetic fields are studied through graphs and tables. Variations in Skin friction and rate of heat transfer are also studied. It is observed that an increase in magnetic parameter decreases the velocity for both water and air. It is also seen that there is a fall in induced magnetic field as magnetic Prandtl number, and magnetic field parameter increase.

  1. Improving the performances of H-Darrieus cross-flow turbines through proper detached end plate designs

    Science.gov (United States)

    Villeneuve, Thierry; Boudreau, Matthieu; Dumas, Guy; CFD Laboratory LMFN Team

    2017-11-01

    Previous studies on H-Darrieus cross-flow turbines have highlighted the fact that their performances are highly sensitive to the detrimental effects associated with the blades tips. Wingtip devices could be designed in order to attenuate these effects, but the benefits of such devices are always impaired by their added viscous drag since they are moving with the turbine's blades. In this context, the development of fixed and detached end plates, i.e., which are not in contact with the turbine's blades, could reduce the tip losses without the undesirable added drag of typical wingtip devices moving with the blades. The case of a single stationary blade with detached end plates has first been investigated with RANS simulations in order to understand the mechanisms responsible for the increase of the blade's lift. An analysis of the vorticity lines' dynamics provides crucial insights into the effects of the gap width between the blade and the detached end plate on the blade's loading and on the intensity of the tip vortices. Based on these observations, various configurations of detached end plates are tested on cross-flow turbines via RANS and DDES simulations. Preliminary results show that appropriate detached end plates can significantly increase the turbines' efficiency. The authors gratefully acknowledge the Natural Sciences and Engineering Research Council of Canada (NSERC) for their financial support as well as Compute Canada and Calcul Québec for their supercomputer allocations.

  2. Experimental and numerical study on transient heat transfer for helium gas flowing over a twisted plate with different length

    International Nuclear Information System (INIS)

    Wang, Li; Liu, Qiusheng; Fukuda, Katsuya

    2015-01-01

    This study was conducted to investigate the transient heat transfer process between the solid surface and the coolant (helium gas) in Very High Temperature Reactor (VHTR). Forced convection transient heat transfer for helium gas flowing over a twisted plate with different length was experimentally and theoretically studied. The heat generation rate of the twisted plate was increased with a function of Q = Q_0exp(t/τ)(where t is time, τ is period). Experiment was carried out at various periods ranged from 35 ms to 14 s and gas temperature of 303 K under 500 kPa. The flow velocities ranged from 4 m/s to 10 m/s. Platinum plates with a thickness of 0.1 mm and width of 4 mm were used as the test heaters. The plates were twisted with the same helical pitch of 20 mm, and length of 26.8 mm, 67.8 mm and 106.4 mm (pitch numbers of 1, 3 and 5), respectively. Based on the experimental data, it was found that the average heat transfer coefficient approaches the quasi-steady-state value when the dimensionless period τ* (τ* = τU/L, U is flow velocity, and L is effective length) is larger than about 100 and it becomes higher when τ* is small. The heat transfer coefficient decreases with the increase of twisted plate length under the same period of heat generation rate. According to the experimental data, the distribution for heat transfer coefficient along the heater is nonlinear. Numerical simulation results were obtained for average surface temperature difference, heat flux and heat transfer coefficient of the twisted plates with different length and showed reasonable agreement with experimental data. Based on the numerical simulation, mechanism of local heat transfer coefficient distribution was clarified. (author)

  3. Experimental study of single- and two-phase flow fields around PWR steam generator tube support plates

    International Nuclear Information System (INIS)

    Bates, J.M.; Stewart, C.W.

    1979-08-01

    Laser-Doppler anemometry (LDA) was used to measure local mean axial velocities and turbulence intnsities at selected locations within a study model dimensionally protypic of an existing PWR steam generator design. The model tube bundle with support plate was installed in a special flow housing that formed part of an isothermal recirculating water flow loop. Flow conditions for this experiment were intended to simulate only typical single-phase flow velocities and were not an attempt to completely model actual steam generator, boiling, two-phase flow conditions. The measurements were performed in water at approximately 85 0 F with test section average velocities of approximately 0.55 and 1.1 fps. These conditions corresponded to Reynolds numbers of approximately 7,000 and approximately 14,000, respectively. Normalized velocity and turbulence intensity ratios are graphically reported. Additional qualitative, photographic investigations of air-water two-phase flows in a PWR steam generator study model were also performed

  4. Pressure-Driven Poiseuille Flow: A Major Component of the Torque-Balance Governing Pacific Plate Motion

    Science.gov (United States)

    Stotz, I. L.; Iaffaldano, G.; Davies, D. R.

    2018-01-01

    The Pacific Plate is thought to be driven mainly by slab pull, associated with subduction along the Aleutians-Japan, Marianas-Izu-Bonin, and Tonga-Kermadec trenches. This implies that viscous flow within the sub-Pacific asthenosphere is mainly generated by overlying plate motion (i.e., Couette flow) and that the associated shear stresses at the lithosphere's base are resisting such motion. Recent studies on glacial isostatic adjustment and lithosphere dynamics provide tighter constraints on the viscosity and thickness of Earth's asthenosphere and, therefore, on the amount of shear stress that asthenosphere and lithosphere mutually exchange, by virtue of Newton's third law of motion. In light of these constraints, the notion that subduction is the main driver of present-day Pacific Plate motion becomes somewhat unviable, as the pulling force that would be required by slabs exceeds the maximum available from their negative buoyancy. Here we use coupled global models of mantle and lithosphere dynamics to show that the sub-Pacific asthenosphere features a significant component of pressure-driven (i.e., Poiseuille) flow and that this has driven at least 50% of the Pacific Plate motion since, at least, 15 Ma. A corollary of our models is that a sublithospheric pressure difference as high as ±50 MPa is required across the Pacific domain.

  5. Effect of rotation on the formation of longitudinal vortices in mixed convection flow over a flat plate

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Ming-Han [Ta-Hwa Institute of Technology, Department of Automation Engineering, Hsinchu (Taiwan); Chen, Chin-Tai [Ta-Hwa Institute of Technology, Department of Industrial Engineering and Management, Hsinchu (Taiwan)

    2006-01-01

    This paper presents a numerical study of the effect of rotation on the formation of longitudinal vortices in mixed convection flow over a flat plate. The criterion on the position of marking the onset of longitudinal vortices is defined in this paper. The onset position characterized by the Goertler number G{sub {delta}} depends on the Grashof number, the rotation number Ro, the Prandtl number Pr and the wave number. The results show that negative rotation stabilizes the boundary layer flow on the surface. On the contrary, positive rotation destabilizes the flow. The numerical data are compared with the experimental results. (orig.)

  6. Turbulent flow and heat transfer from a slot jet impinging on a moving plate

    International Nuclear Information System (INIS)

    Chattopadhyay, Himadri; Saha, Sujoy K.

    2003-01-01

    The flow field due to an impinging jet over a moving surface at a moderately high Reynolds number, emanating from a rectangular slot nozzle has been computed using the large eddy simulation technique. A dynamic subgrid-scale stress model has been used for the small scales of turbulence. The velocity of the impinging surface perpendicular to the jet velocity has been varied up to two times the jet velocity at the nozzle exit. Turbulence quantities such as kinetic energy, production rate of turbulent kinetic energy and the Reynolds stresses are calculated for different surface velocities. It has been observed that, while the turbulent kinetic energy increases with increasing velocity of the impinging surface, production rate of turbulence initially increases with increasing surface velocity and then comes down. By analyzing the components of turbulent production it was found that P 33 is the dominant term up to the surface velocity of one unit and when the surface velocity is two times the jet velocity at the nozzle exit, the major contribution to turbulence production comes from P 13 and partly from P 11 . Heat transfer from the plate initially increases with non-dimensional surface velocity up to 1.2 and then comes down

  7. Natural Convection Flow of Fractional Nanofluids Over an Isothermal Vertical Plate with Thermal Radiation

    Directory of Open Access Journals (Sweden)

    Constantin Fetecau

    2017-03-01

    Full Text Available The studies of classical nanofluids are restricted to models described by partial differential equations of integer order, and the memory effects are ignored. Fractional nanofluids, modeled by differential equations with Caputo time derivatives, are able to describe the influence of memory on the nanofluid behavior. In the present paper, heat and mass transfer characteristics of two water-based fractional nanofluids, containing nanoparticles of CuO and Ag, over an infinite vertical plate with a uniform temperature and thermal radiation, are analytically and graphically studied. Closed form solutions are determined for the dimensionless temperature and velocity fields, and the corresponding Nusselt number and skin friction coefficient. These solutions, presented in equivalent forms in terms of the Wright function or its fractional derivatives, have also been reduced to the known solutions of ordinary nanofluids. The influence of the fractional parameter on the temperature, velocity, Nusselt number, and skin friction coefficient, is graphically underlined and discussed. The enhancement of heat transfer in the natural convection flows is lower for fractional nanofluids, in comparison to ordinary nanofluids. In both cases, the fluid temperature increases for increasing values of the nanoparticle volume fraction.

  8. Heat transfer from a plate cooled by a water film with countercurrent air flow

    International Nuclear Information System (INIS)

    Ambrosini, W.; Manfredini, A.; Mariotti, F.; Oriolo, F.; Vigni, P.

    1995-01-01

    An experimental program at the University of Pisa provides specific data for the evaluation of heat and mass transfer by falling film evaporation. The problem is addressed primarily because of its relevance to the study of the behavior of passive containment cooling systems in simplified pressurized water reactors. In these plants, after an accident that releases vapor from the primary circuit, the steel containment envelope is cooled either by an ascending stream of air in natural circulation or by the combination of air flow and falling film evaporation. To qualify models for the prediction of the heat transfer capabilities in postulated accident conditions, researchers have built an experimental facility consisting of a flat heated plate with water sprays and a fan to simulate a countercurrent air stream. The range of relevant parameters to be investigated has been determined on the basis of integral calculations performed for the AP600 reactor containment. The facility has enabled the collection of data that confirm the adequacy of the classical heat and mass transfer analogy in predicting evaporation phenomena. Further developments in the research are needed to confirm the first results and to extend the experimental database by considering more subtle aspects of the phenomenon such as the characteristics of surface waviness of the water film and its effect on heat transfer

  9. Flow patterns of GaInSn liquid on inclined stainless steel plate under a range of magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Juan-Cheng, E-mail: yangjc@xjtu.edu.cn [State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace, Xi’an Jiaotong University, Xi’an, Shanxi 710049 (China); Qi, Tian-Yu [School of Engineering Sciences, University of Chinese Academy and Sciences, Beijing 100049 (China); Ni, Ming-Jiu, E-mail: mjni@ucas.ac.cn [School of Engineering Sciences, University of Chinese Academy and Sciences, Beijing 100049 (China); Wang, Zeng-Hui [School of Engineering Sciences, University of Chinese Academy and Sciences, Beijing 100049 (China)

    2016-11-01

    Highlights: • The liquid GaInSn metal flow loop was built to study some fusion related liquid metal MHD phenomenon. • The flow patterns of GaInSn free surface flow with the change of Re number and Ha number were got by lot of experiments. • Some detailed descriptions of these flow patterns were also made, and a solid conclusion which agreed with some previous studies was got. - Abstract: In the present paper, some preliminary experimental studies have been conducted to show the flow pattern of liquid metal flow using visualization method. For the convenience of experiments in lab, Ga{sup 67}In{sup 20.5}Sn{sup 12.5} in liquid state at room temperature is used. A test section made by stainless steel is inserted in a traverse magnetic field with strength (B{sub 0}) varies from 0 to 1.28 T. The inclined angle of stainless steel plate in test section is about 9°. Visualization results obtained by high-speed camera (Phantom M/LC 310) shown that GaInSn liquid flow on inclined stainless steel plate behaved unstable liquid column flow pattern in the low flow rate, while behaved large area spreading flow pattern with small waves on the free surface in the large flow rate. However, in the magnetic field, under the action of electromagnetic force, the flow patterns of GaInSn liquid have some significant changes on the spreading width and surface structure of free surface. Some detailed analyses on these changes have been also showed in the present paper. Plans for future work are also presented.

  10. Measurement of profile and intensity of proton beam by an integrating current transformer and a segmented parallel-plate ion chamber for the AGS-spallation target experiment (ASTE)

    International Nuclear Information System (INIS)

    Meigo, Shin-ichiro; Nakashima, Hiroshi; Takada, Hiroshi

    2001-03-01

    Profile and intensity of proton beams incident to a mercury target were measured for the experiments under AGS-spallation Target Experiment (ASTE) collaboration. Protons of 1.94, 12 and 24 GeV energy were measured for a temperature, pressure wave and neutronics in the mercury target. For the beam profile measurement, segmented parallel-plate ion chamber (CHIDORI) was used as the online detector. Imaging plates (IP) were also used for the profile measurement with aluminum activation foils as the image converter. An integrating current transformer (ICT) and activation method by Cu foil were used for the measurement of beam intensity. The beam profile obtained by CHIDORI gives a good agreement with the results with the IP. The beam intensity obtained by ICT agrees with the data obtained by the activation technique within ±3% for 12 and 24 GeV cases. Furthermore, these results show in good agreement with those obtained by the monitor of segmented wire ionization chamber (SWIC) and secondary emission chamber (SEC) installed by the AGS team. Therefore, a reliable beam monitor technique was established, so that the analysis of the experiment such as temperature and pressure wave can be normalized by the number of incident protons. (author)

  11. A two-dimensional numerical study of the flow inside the combustion chamber of a motored rotary engine

    Science.gov (United States)

    Shih, T. I-P.; Yang, S. L.; Schock, H. J.

    1986-01-01

    A numerical study was performed to investigate the unsteady, multidimensional flow inside the combustion chambers of an idealized, two-dimensional, rotary engine under motored conditions. The numerical study was based on the time-dependent, two-dimensional, density-weighted, ensemble-averaged conservation equations of mass, species, momentum, and total energy valid for two-component ideal gas mixtures. The ensemble-averaged conservation equations were closed by a K-epsilon model of turbulence. This K-epsilon model of turbulence was modified to account for some of the effects of compressibility, streamline curvature, low-Reynolds number, and preferential stress dissipation. Numerical solutions to the conservation equations were obtained by the highly efficient implicit-factored method of Beam and Warming. The grid system needed to obtain solutions were generated by an algebraic grid generation technique based on transfinite interpolation. Results of the numerical study are presented in graphical form illustrating the flow patterns during intake, compression, gaseous fuel injection, expansion, and exhaust.

  12. A two-dimensional numerical study of the flow inside the combustion chambers of a motored rotary engine

    Science.gov (United States)

    Shih, T. I. P.; Yang, S. L.; Schock, H. J.

    1986-01-01

    A numerical study was performed to investigate the unsteady, multidimensional flow inside the combustion chambers of an idealized, two-dimensional, rotary engine under motored conditions. The numerical study was based on the time-dependent, two-dimensional, density-weighted, ensemble-averaged conservation equations of mass, species, momentum, and total energy valid for two-component ideal gas mixtures. The ensemble-averaged conservation equations were closed by a K-epsilon model of turbulence. This K-epsilon model of turbulence was modified to account for some of the effects of compressibility, streamline curvature, low-Reynolds number, and preferential stress dissipation. Numerical solutions to the conservation equations were obtained by the highly efficient implicit-factored method of Beam and Warming. The grid system needed to obtain solutions were generated by an algebraic grid generation technique based on transfinite interpolation. Results of the numerical study are presented in graphical form illustrating the flow patterns during intake, compression, gaseous fuel injection, expansion, and exhaust.

  13. Visualization study of interaction with 2-D film flow on the vertical plate and lateral air velocity for DVI system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han Sol; Lee, Jae Young [Handong Global University, Pohang (Korea, Republic of); Euh, Dong Jin; Kim, Jong Rok [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    The present study investigates liquid film flow generated in a downcomer of direct vessel injection (DVI) system which is employed as an emergency core cooling (ECC) system during a loss of coolant accident in the Korea nuclear power plant APR1400. During the late reflooding, complicated multi-phase flow phenomena including the wavy film flow, film breakup, entrainment, liquid film shift due to interfacial drag and gas jet impingement occur. In order to obtain a proper scaling law of the flow, local information of the flow was investigated experimentally and also numerically. A series of experiments were conducted in the 1/20 modified linear scaled plate type test rig to analyze a liquid film from ECC water injection through the DVI nozzle to the downcomer wall. A confocal chromatic sensor was used to measure the local instantaneous liquid film thickness. In this study, the average flow information of the downcomer was analyzed through the information about the thickness, speed, droplet size and speed of highly precise liquid film flow in the structure that occurs in a 2-dimensional liquid film flow, rather than film flow, onset of entrainment, droplet velocity, and size which have been studied in 1-dimension of the existing annular flow. The multi-dimensional flow characteristic information of downcomer can be utilized as the basic data for nuclear safety analysis in the future.

  14. Effects of rotation on MHD flow past an accelerated isothermal vertical plate with heat and mass diffusion

    Directory of Open Access Journals (Sweden)

    Muthucumaraswamy R.

    2010-01-01

    Full Text Available An exact analysis of rotation effects on unsteady flow of an incompressible and electrically conducting fluid past a uniformly accelerated infinite isothermal vertical plate, under the action of transversely applied magnetic field has been presented. The plate temperature is raised to Tw and the concentration level near the plate is also raised to C′w . The dimensionless governing equations are solved using Laplace-transform technique. The velocity profiles, temperature and concentration are studied for different physical parameters like thermal Grashof number, mass Grashof number, Schmidt number, Prandtl number and time. It is observed that the velocity increases with increasing values of thermal Grashof number or mass Grashof number. It is also observed that the velocity increases with decreasing magnetic field parameter.

  15. Re-evaluation of the Pressure Effect for Nucleation in Laminar Flow Diffusion Chamber Experiments with Fluent and the Fine Particle Model

    Czech Academy of Sciences Publication Activity Database

    Herrmann, E.; Hyvärinen, A.-P.; Brus, David; Lihavainen, H.; Kulmala, M.

    2009-01-01

    Roč. 113, č. 8 (2009), s. 1434-1439 ISSN 1089-5639 Institutional research plan: CEZ:AV0Z40720504 Keywords : laminar flow diffusion chamber * experimental data * fine particle model Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.899, year: 2009

  16. Mass transfer, fluid flow and membrane properties in flat and corrugated plate hyperfiltration modules

    NARCIS (Netherlands)

    Racz, I.G.; Groot Wassink, J.; Klaassen, R.

    1986-01-01

    Concentration polarisation, decreasing the efficiency in membrane separation processes, can be reduced by increasing mass transfer between membrane surface and bulk of the feed stream. Analogous to techniques used in plate heat exchangers efforts have been made to enhance mass transfer in a plate

  17. Newtonian heating effect on unsteady hydromagnetic Casson fluid flow past a flat plate with heat and mass transfer

    Directory of Open Access Journals (Sweden)

    M. Das

    2015-12-01

    Full Text Available The influence of Newtonian heating on heat and mass transfer in unsteady hydromagnetic flow of a Casson fluid past a vertical plate in the presence of thermal radiation and chemical reaction is studied. The Casson fluid model is used to distinguish the non-Newtonian fluid behavior. The fluid flow is induced due to periodic oscillations of the plate along its length and a uniform transverse magnetic field is applied in a direction which is normal to the direction of fluid flow. The partial differential equations governing the flow, heat, and mass transfer are transformed to non-dimensional form using suitable non-dimensional variables which are then solved analytically by using Laplace transform technique. The numerical values of the fluid velocity, fluid temperature, and species concentration are depicted graphically whereas the values of skin-friction, Nusselt number, and Sherwood number are presented in tabular form. It is noticed that the fluid velocity and temperature decrease with increasing values of Casson parameter while concentration decreases with increasing values of chemical reaction parameter and Schmidt number. Such a fluid flow model has several industrial and medical applications such as in glass manufacturing, paper production, purification of crude oil and study of blood flow in the cardiovascular system.

  18. Flow cytometric bacterial cell counts challenge conventional heterotrophic plate counts for routine microbiological drinking water monitoring

    KAUST Repository

    Van Nevel, S.

    2017-02-08

    Drinking water utilities and researchers continue to rely on the century-old heterotrophic plate counts (HPC) method for routine assessment of general microbiological water quality. Bacterial cell counting with flow cytometry (FCM) is one of a number of alternative methods that challenge this status quo and provide an opportunity for improved water quality monitoring. After more than a decade of application in drinking water research, FCM methodology is optimised and established for routine application, supported by a considerable amount of data from multiple full-scale studies. Bacterial cell concentrations obtained by FCM enable quantification of the entire bacterial community instead of the minute fraction of cultivable bacteria detected with HPC (typically < 1% of all bacteria). FCM measurements are reproducible with relative standard deviations below 3% and can be available within 15 min of samples arriving in the laboratory. High throughput sample processing and complete automation are feasible and FCM analysis is arguably less expensive than HPC when measuring more than 15 water samples per day, depending on the laboratory and selected staining procedure(s). Moreover, many studies have shown FCM total (TCC) and intact (ICC) cell concentrations to be reliable and robust process variables, responsive to changes in the bacterial abundance and relevant for characterising and monitoring drinking water treatment and distribution systems. The purpose of this critical review is to initiate a constructive discussion on whether FCM could replace HPC in routine water quality monitoring. We argue that FCM provides a faster, more descriptive and more representative quantification of bacterial abundance in drinking water.

  19. Flow cytometric bacterial cell counts challenge conventional heterotrophic plate counts for routine microbiological drinking water monitoring

    KAUST Repository

    Van Nevel, S.; Koetzsch, S.; Proctor, C.R.; Besmer, M.D.; Prest, E.I.; Vrouwenvelder, Johannes S.; Knezev, A.; Boon, N.; Hammes, F.

    2017-01-01

    Drinking water utilities and researchers continue to rely on the century-old heterotrophic plate counts (HPC) method for routine assessment of general microbiological water quality. Bacterial cell counting with flow cytometry (FCM) is one of a number of alternative methods that challenge this status quo and provide an opportunity for improved water quality monitoring. After more than a decade of application in drinking water research, FCM methodology is optimised and established for routine application, supported by a considerable amount of data from multiple full-scale studies. Bacterial cell concentrations obtained by FCM enable quantification of the entire bacterial community instead of the minute fraction of cultivable bacteria detected with HPC (typically < 1% of all bacteria). FCM measurements are reproducible with relative standard deviations below 3% and can be available within 15 min of samples arriving in the laboratory. High throughput sample processing and complete automation are feasible and FCM analysis is arguably less expensive than HPC when measuring more than 15 water samples per day, depending on the laboratory and selected staining procedure(s). Moreover, many studies have shown FCM total (TCC) and intact (ICC) cell concentrations to be reliable and robust process variables, responsive to changes in the bacterial abundance and relevant for characterising and monitoring drinking water treatment and distribution systems. The purpose of this critical review is to initiate a constructive discussion on whether FCM could replace HPC in routine water quality monitoring. We argue that FCM provides a faster, more descriptive and more representative quantification of bacterial abundance in drinking water.

  20. Flow Structure and Heat Transfer of Jet Impingement on a Rib-Roughened Flat Plate

    Directory of Open Access Journals (Sweden)

    Abdulrahman H. Alenezi

    2018-06-01

    Full Text Available The jet impingement technique is an effective method to achieve a high heat transfer rate and is widely used in industry. Enhancing the heat transfer rate even minimally will improve the performance of many engineering systems and applications. In this numerical study, the convective heat transfer process between orthogonal air jet impingement on a smooth, horizontal surface and a roughened uniformly heated flat plate is studied. The roughness element takes the form of a circular rib of square cross-section positioned at different radii around the stagnation point. At each location, the effect of the roughness element on heat transfer rate was simulated for six different heights and the optimum rib location and rib dimension determined. The average Nusselt number has been evaluated within and beyond the stagnation region to better quantify the heat transfer advantages of ribbed surfaces over smooth surfaces. The results showed both flow and heat transfer features vary significantly with rib dimension and location on the heated surface. This variation in the streamwise direction included both augmentation and decrease in heat transfer rate when compared to the baseline no-rib case. The enhancement in normalized averaged Nusselt number obtained by placing the rib at the most optimum radial location R/D = 2 was 15.6% compared to the baseline case. It was also found that the maximum average Nusselt number for each location was achieved when the rib height was close to the corresponding boundary layer thickness of the smooth surface at the same rib position.

  1. Modeling of Uneven Flow and Electromagnetic Field Parameters in the Combustion Chamber of Liquid Rocket Engine with a Near-wall Layer Available

    Directory of Open Access Journals (Sweden)

    A. V. Rudinskii

    2015-01-01

    Full Text Available The paper concerns modeling of an uneven flow and electromagnetic field parameters in the combustion chamber of the liquid rocket engine with a near-wall layer available.The research objective was to evaluate quantitatively influence of changing model chamber mode of the liquid rocket engine on the electro-physical characteristics of the hydrocarbon fuel combustion by-products.The main method of research was based on development of a final element model of the flowing path of the rocket engine chamber and its adaptation to the boundary conditions.The paper presents a developed two-dimensional non-stationary mathematical model of electro-physical processes in the liquid rocket engine chamber using hydrocarbon fuel. The model takes into consideration the features of a gas-dynamic contour of the engine chamber and property of thermo-gas-dynamic characteristics of the ionized products of combustion of hydrocarbonic fuel. Distributions of magnetic field intensity and electric conductivity received and analyzed taking into account a low-temperature near-wall layer. Special attention is paid to comparison of obtained calculation values of the electric current, which is taken out from intrachamber space of the engine with earlier published data of other authors.

  2. Study of the influence of water properties dependency with the temperature in a laminar downward flow between parallel flat plates

    International Nuclear Information System (INIS)

    Delmastro, Dario F.; Chasseur, A.F.; Garcia, Juan C.

    2007-01-01

    In this work we develop a model that contemplates stationary completely developed laminar downward flow between flat parallel plates with uniform and constant heat fluxes. The Boussinesq approach is used in the momentum equation, taking into account the change of the density with the temperature only in the gravitational term. The system is at atmospheric pressure and the dependencies of the density and the thermal conductivity with the temperature are also considered. The velocity and temperature profiles, the friction factor, the heat transfer coefficient and the Nusselt Number are calculated, for different flow rates and heating powers. The results allow to obtain some conclusions that can be of interest in the study of research reactors with forced downward refrigeration and flat plate fuels, although these calculations do not exactly represent the real behavior inside these channels. (author) [es

  3. Free convection flow of some fractional nanofluids over a moving vertical plate with uniform heat flux and heat source

    Science.gov (United States)

    Azhar, Waqas Ali; Vieru, Dumitru; Fetecau, Constantin

    2017-08-01

    Free convection flow of some water based fractional nanofluids over a moving infinite vertical plate with uniform heat flux and heat source is analytically and graphically studied. Exact solutions for dimensionless temperature and velocity fields, Nusselt numbers, and skin friction coefficients are established in integral form in terms of modified Bessel functions of the first kind. These solutions satisfy all imposed initial and boundary conditions and reduce to the similar solutions for ordinary nanofluids when the fractional parameters tend to one. Furthermore, they reduce to the known solutions from the literature when the plate is fixed and the heat source is absent. The influence of fractional parameters on heat transfer and fluid motion is graphically underlined and discussed. The enhancement of heat transfer in such flows is higher for fractional nanofluids in comparison with ordinary nanofluids. Moreover, the use of fractional models allows us to choose the fractional parameters in order to get a very good agreement between experimental and theoretical results.

  4. Active control of noise amplification in the flow over a square leading-edge flat plate utilizing DBD plasma actuator

    Science.gov (United States)

    Yadong, HUANG; Benmou, ZHOU

    2018-05-01

    Perturbation is generally considered as the flow noise, and its energy can gain transient growth in the separation bubble. The amplified perturbations may cause unstable Kelvin–Helmohltz vortices which induce the three-dimensional transition. Active control of noise amplification via dielectric barrier discharge plasma actuator in the flow over a square leading-edge flat plate is numerically studied. The actuator is installed near the plate leading-edge where the separation bubble is formed. The maximum energy amplification of perturbations is positively correlated with the separation bubble scale which decreases with the increasing control parameters. As the magnitude of noise amplification is reduced, the laminar-turbulent transition is successfully suppressed.

  5. Boundary Layer Flow and Heat Transfer with Variable Fluid Properties on a Moving Flat Plate in a Parallel Free Stream

    Directory of Open Access Journals (Sweden)

    Norfifah Bachok

    2012-01-01

    Full Text Available The steady boundary layer flow and heat transfer of a viscous fluid on a moving flat plate in a parallel free stream with variable fluid properties are studied. Two special cases, namely, constant fluid properties and variable fluid viscosity, are considered. The transformed boundary layer equations are solved numerically by a finite-difference scheme known as Keller-box method. Numerical results for the flow and the thermal fields for both cases are obtained for various values of the free stream parameter and the Prandtl number. It is found that dual solutions exist for both cases when the fluid and the plate move in the opposite directions. Moreover, fluid with constant properties shows drag reduction characteristics compared to fluid with variable viscosity.

  6. Shape effects of nanoparticles on the squeezed flow between two Riga plates in the presence of thermal radiation

    Science.gov (United States)

    Ahmed, Naveed; Adnan; Khan, Umar; Tauseef Mohyud-Din, Syed; Waheed, Asif

    2017-07-01

    This paper aims to explore the flow of water saturated with copper nanoparticles of different shapes between parallel Riga plates. The plates are placed horizontally in the coordinate axis. Influence of the linear thermal radiation is also taken into account. The equations governing the flow have been transformed into a nondimensional form by employing a set of similarity transformations. The obtained system is solved analytically (variation-of-parameters method) and numerically (Runge-Kutta scheme). Under certain conditions, a special case of the model is also explored. Furthermore, influences of the physical quantities on velocity and thermal fields are discussed with the graphical aid over the domain of interest. The quantities of engineering and practical interest (skin friction coefficient and local rate of heat transfer) are also explored graphically.

  7. Heat transfer in a Couette flow with part of the space between the plates filled with porous medium

    International Nuclear Information System (INIS)

    Carrocci, L.R.; Liu, C.Y.; Ismail, K.A.R.

    1982-01-01

    The effect of various parameters in the temperature profile is shown under boundary conditions for the Couette flow between infinite plates with part of the space filled with porous medium. The parameters observed are: pressure gradient, permeability, the non-dimensional product PE (Prandtl number x Eckert number), the relation between the thermal conductibility coefficient between porous region and pure fluid, and finally the non-dimensional product PR (Prandtl number x Reynolds number). (E.G.) [pt

  8. Thermal development of the laminar flow of a Bingham fluid between two plane plates with viscous dissipation

    Energy Technology Data Exchange (ETDEWEB)

    Boualit, A.; Boualit, S. [Unite de recherche appliquee en energies renouvelables, Ghardaia (Algeria); Zeraibi, N. [Universite de Boumerdes, Faculte des hydrocarbures dept. Transport et equipement, Boumerdes (Algeria); Amoura, M. [Universite des Sciences et de la Technologie Houari Boumedienne, Faculte de Physique, Dept. Energetique, Alger (Algeria)

    2011-01-15

    The thermal development of the hydrodynamically developing laminar flow of a viscoplastic fluid (fluid of Bingham) between two plane plates maintained at a constant temperature has been studied numerically. This analysis has shown the effect caused by inertia and the rheological behaviour of the fluid on the velocity, pressure and temperature fields. The effects of Bingham and Peclet numbers on the Nusselt values with the inclusion of viscous dissipation are also discussed. (authors)

  9. HEAT AND MASS TRANSFER FOR VISCO-ELASTIC MHD BOUNDARY LAYER FLOW PAST A VERTICAL FLAT PLATE

    OpenAIRE

    Rita Choudhury; Hridi Ranjan Deb

    2012-01-01

    The two-dimensional free convection flow of visco-elastic and electrically conducting fluid past a vertical impermeable flat plate is considered in presence of a uniform transverse magnetic field. The governing equations are reduced to ordinary differential equation by introducing appropriate co-ordinate transformation. The analytical expressions for the velocity, temperature and species concentration fields have been obtained. The corresponding expressions for the non-dimensional rates of he...

  10. Hall effects on free convection hydromagnetic boundary layer flow of Rivlin-Ericksen fluid past a vertical plate

    International Nuclear Information System (INIS)

    Jha, P.K.

    1986-01-01

    An attempt has been made to study the problem of free convection hydromagnetic flow of an elastico-viscous fluid past a porous vertical plate in a rotating frame of reference taking ohmic and viscous dissipations into account in the presence of Hall current. The nature of velocity profile shows the existence of multiple boundary layers. Their 'thickness' is seen to decrease with increasing values of Ekman, Hartman and Prandtl numbers and Hall parameter. The graphical study reveals that the increasing values of Hall parameter and Ekman number (for a fixed large value of Hall parameter) exert opposite influence on the flow. (author). 11 refs., 2 tables

  11. General Observations of the Time-Dependent Flow Field Around Flat Plates in Free Fall

    DEFF Research Database (Denmark)

    Hærvig, Jakob; Jensen, Anna Lyhne; Pedersen, Marie Cecilie

    2015-01-01

    a six degrees of freedom (6DOF) solver and a dynamic mesh. To validate the simulation, the trajectories of aluminium plates falling in water are recorded by digital camera recordings and compared to the simulation. The simulation is able to calculate the motion of the plate within each time step...... with high accuracy, and thereby allowing the whole trajectory to be predicted with fair accuracy. With the numerical model able to predict the free fall and the complex plate fluid interactions, fluids forces can be extracted for model development in future studies....

  12. Magnetohydrodynamics effect on three-dimensional viscous incompressible flow between two horizontal parallel porous plates and heat transfer with periodic injection/suction

    Directory of Open Access Journals (Sweden)

    R. C. Chaudhary

    2004-11-01

    Full Text Available We investigate the hydromagnetic effect on viscous incompressible flow between two horizontal parallel porous flat plates with transverse sinusoidal injection of the fluid at the stationary plate and its corresponding removal by periodic suction through the plate in uniform motion. The flow becomes three dimensional due to this injection/suction velocity. Approximate solutions are obtained for the flow field, the pressure, the skin-friction, the temperature field, and the rate of heat transfer. The dependence of solution on M (Hartmann number and λ (injection/suction is investigated by the graphs and tables.

  13. Effects of Cooling Fluid Flow Rate on the Critical Heat Flux and Flow Stability in the Plate Fuel Type 2 MW TRIGA Reactor

    OpenAIRE

    H. P. Rahardjo; V. I. Sri Wardhani

    2017-01-01

    The conversion program of the 2 MW TRIGA reactor in Bandung consisted of the replacement of cylindrical fuel (produced by General Atomic) with plate fuel (produced by BATAN). The replacement led into the change of core cooling process from upward natural convection type to downward forced convection type, and resulted in different thermohydraulic safety criteria, such as critical heat flux (CHF) limit, boiling limit, and cooling fluid flow stability. In this paper, a thermohydraulic safety an...

  14. Viscous dissipation effects on heat transfer in flow past a continuous moving plate

    Digital Repository Service at National Institute of Oceanography (India)

    Soundalgekar, V.M.; Murty, T.V.R.

    The study of thermal boundary layer on taking into account the viscous dissipative heat, on a continuously moving semi-infinite flat plate is presented here.Similarity solutions are derived and the resulting equations are integrated numerically...

  15. Pyrolysis and Boundary Layer Combustion of a Non-Charring Solid Plate Under Forced Flow

    National Research Council Canada - National Science Library

    Ananth, Ramagopal

    2003-01-01

    Solutions of Navier-Stokes (NS) equations were obtained for burning rate Nu and temperature distributions for a flat PMMA plate using an iterative method to impose steady-state, pyrolysis kinetics at the surface...

  16. Analysis of Heat Transfer and Pressure Drop for a Gas Flowing Through a set of Multiple Parallel Flat Plates at High Temperatures

    Science.gov (United States)

    Einstein, Thomas H.

    1961-01-01

    Equations were derived representing heat transfer and pressure drop for a gas flowing in the passages of a heater composed of a series of parallel flat plates. The plates generated heat which was transferred to the flowing gas by convection. The relatively high temperature level of this system necessitated the consideration of heat transfer between the plates by radiation. The equations were solved on an IBM 704 computer, and results were obtained for hydrogen as the working fluid for a series of cases with a gas inlet temperature of 200 R, an exit temperature of 5000 0 R, and exit Mach numbers ranging from 0.2 to O.8. The length of the heater composed of the plates ranged from 2 to 4 feet, and the spacing between the plates was varied from 0.003 to 0.01 foot. Most of the results were for a five- plate heater, but results are also given for nine plates to show the effect of increasing the number of plates. The heat generation was assumed to be identical for each plate but was varied along the length of the plates. The axial variation of power used to obtain the results presented is the so-called "2/3-cosine variation." The boundaries surrounding the set of plates, and parallel to it, were assumed adiabatic, so that all the power generated in the plates went into heating the gas. The results are presented in plots of maximum plate and maximum adiabatic wall temperatures as functions of parameters proportional to f(L/D), for the case of both laminar and turbulent flow. Here f is the Fanning friction factor and (L/D) is the length to equivalent diameter ratio of the passages in the heater. The pressure drop through the heater is presented as a function of these same parameters, the exit Mach number, and the pressure at the exit of the heater.

  17. Experimental and numerical investigation of the iso-thermal flow characteristics within a cylindrical chamber with multiple planar-symmetric impinging jets

    Science.gov (United States)

    Long, Shen; Lau, Timothy C. W.; Chinnici, Alfonso; Tian, Zhao Feng; Dally, Bassam B.; Nathan, Graham J.

    2017-10-01

    We present a joint experimental and numerical study of the flow structure within a cylindrical chamber generated by planar-symmetric isothermal jets, under conditions of relevance to a wide range of practical applications, including the Hybrid Solar Receiver Combustor (HSRC) technology. The HSRC features a cavity with a coverable aperture to allow it to be operated as either a combustion chamber or a solar receiver, with multiple burners to direct a flame into the chamber and a heat exchanger that absorbs the heat from both energy sources. In this study, we assess the cases of two or four inlet jets (simulating the burners), configured in a planar-symmetric arrangement and aligned at an angle to the axis (αj) over the range of 0°-90°, at a constant inlet Reynolds number of ReD = 10 500. The jets were positioned in the same axial plane near the throat and interact with each other and the cavity walls. Measurements obtained with particle image velocimetry were used together with numerical modeling employing Reynolds-averaged Navier-Stokes methods to characterize the large-scale flow field within selected configurations of the device. The results reveal a significant dependence of the mean flow-field on αj and the number of inlet jets (Nj). Four different flow regimes with key distinctive features were identified within the range of αj and Nj considered here. It was also found that αj has a controlling influence on the extent of back-flow through the throat, the turbulence intensity, the flow stability, and the dominant recirculation zone, while Nj has a secondary influence on the turbulence intensity, the flow stability, and the transition between each flow regime.

  18. Characterization of a tubular flow chamber for studying platelet interaction with biologic and prosthetic materials: deposition of indium 111-labeled platelets on collagen, subendothelium, and expanded polytetrafluoroethylene

    International Nuclear Information System (INIS)

    Badimon, L.; Turitto, V.; Rosemark, J.A.; Badimon, J.J.; Fuster, V.

    1987-01-01

    A plastic (Plexiglas) chamber for evaluating platelet deposition under controlled hemodynamic conditions has been developed. The perfusion chamber has been designed to retain the cylindrical shape typical of the vasculature, to be flexible enough to accept a variety of biologic and prosthetic materials, and to simulate a broad range of physiologic flow conditions in either an ex vivo or in vitro perfusion system. Three type of surfaces were exposed to blood flowing directly from the carotid artery of a heparinized pig through the perfusion chamber: de-endothelialized pig aorta, collagen strips from rabbit Achilles tendon, and an expanded polytetrafluoroethylene material (Gore-Tex). Platelets, previously radiolabeled with indium 111 and injected into the animal, were quantified on the material surface, and the total number of deposited platelets determined for a range of blood flow rates (5 to 40 ml/min) and exposure times (0.5 to 20 minutes). The deposition rates were correlated with theory for describing the mass transport of platelets to the test surface. At the wall shear rates investigated (105 to 850 sec-1), the deposition of platelets on subendothelium was strongly dependent on the local flow conditions. Values of deposition on Gore-Tex obtained at similar flow conditions (105 to 425 sec-1) were reduced compared with that observed on subendothelium and showed a markedly weaker dependence on the shear rate. In contrast, deposition of platelets on collagen was more than an order of magnitude greater than on subendothelium and showed a dependence on flow only at the lowest flow rate studied (10 ml/min). The results indicate that collagen is much more reactive than subendothelium and Gore-Tex with respect to the growth and stability of platelet aggregates and moreover suggest that flow mechanisms for depositing platelets on various surface may be substantially different

  19. Characterization of a tubular flow chamber for studying platelet interaction with biologic and prosthetic materials: deposition of indium 111-labeled platelets on collagen, subendothelium, and expanded polytetrafluoroethylene

    Energy Technology Data Exchange (ETDEWEB)

    Badimon, L.; Turitto, V.; Rosemark, J.A.; Badimon, J.J.; Fuster, V.

    1987-12-01

    A plastic (Plexiglas) chamber for evaluating platelet deposition under controlled hemodynamic conditions has been developed. The perfusion chamber has been designed to retain the cylindrical shape typical of the vasculature, to be flexible enough to accept a variety of biologic and prosthetic materials, and to simulate a broad range of physiologic flow conditions in either an ex vivo or in vitro perfusion system. Three type of surfaces were exposed to blood flowing directly from the carotid artery of a heparinized pig through the perfusion chamber: de-endothelialized pig aorta, collagen strips from rabbit Achilles tendon, and an expanded polytetrafluoroethylene material (Gore-Tex). Platelets, previously radiolabeled with indium 111 and injected into the animal, were quantified on the material surface, and the total number of deposited platelets determined for a range of blood flow rates (5 to 40 ml/min) and exposure times (0.5 to 20 minutes). The deposition rates were correlated with theory for describing the mass transport of platelets to the test surface. At the wall shear rates investigated (105 to 850 sec-1), the deposition of platelets on subendothelium was strongly dependent on the local flow conditions. Values of deposition on Gore-Tex obtained at similar flow conditions (105 to 425 sec-1) were reduced compared with that observed on subendothelium and showed a markedly weaker dependence on the shear rate. In contrast, deposition of platelets on collagen was more than an order of magnitude greater than on subendothelium and showed a dependence on flow only at the lowest flow rate studied (10 ml/min). The results indicate that collagen is much more reactive than subendothelium and Gore-Tex with respect to the growth and stability of platelet aggregates and moreover suggest that flow mechanisms for depositing platelets on various surface may be substantially different.

  20. NUMERICAL AND EXPERIMENTAL INVESTIGATION ON THE FLUTTER OF CANTILEVERED PLATES WITH FREE LEADING EDGE IN AXIAL FLOW

    Directory of Open Access Journals (Sweden)

    I. P. G. SOPAN RAHTIKA

    2017-10-01

    Full Text Available This paper reports the results of the numerical and experimental investigation on the flutter of cantilevered thin flat plates with free leading edge in axial flow. Three methods of in-vacuo modal analyses of the plates are presented and compared in this paper, namely the finite element modal analysis using ANSYS STUDENT Modal, the analytical beam model, and the experimental modal analysis. In this study, the numerical Fluid Structure Interaction was performed using the ANSYS STUDENT Structural Transient Analysis and ANSYS STUDENT CFX to obtain the system response in the time domain. Furthermore, the experimental investigation was conducted in the smooth flow of a wind tunnel to observe the flutter speeds of the plates and their vibration characteristics. The plates’ vibration behaviors were mapped on the normalized air speed. The normalized air speed can be divided into four speed zones based on the experimental plates’ vibration characteristics. A new finding observed during the experiments is the presence of intermittent vibration behavior that is unique to the free leading edge configuration and has not been reported by other researchers in the earlier references of the clamped leading edge configuration. The potential application of this Fluid Structure Interaction configuration to wind harvesting is inquired.

  1. Influence of slip velocity in Herschel-Bulkley fluid flow between parallel plates - A mathematical study

    International Nuclear Information System (INIS)

    Sankar, D. S.; Lee, U Sik

    2016-01-01

    This theoretical study investigates three types of basic flows of viscous incompressible Herschel-Bulkley fluid such as (i) plane Couette flow, (ii) Poiseuille flow and (iii) generalized Couette flow with slip velocity at the boundary. The analytic solutions to the nonlinear boundary value problems have been obtained. The effects of various physical parameters on the velocity, flow rate, wall shear stress and frictional resistance to flow are analyzed through appropriate graphs. It is observed that in plane Poiseuille flow and generalized Couette flow, the velocity and flow rate of the fluid increase considerably with the increase of the slip parameter, power law index, pressure gradient. The fluid velocity is significantly higher in plane Poiseuille flow than in plane Couette flow. The wall shear stress and frictional resistance to flow decrease considerably with the increase of the power law index and increase significantly with the increase of the yield stress of the fluid. The wall shear stress and frictional resistance to flow are considerably higher in plane Poiseuille flow than in generalized Couette flow.

  2. Heat and Mass Transfer with Free Convection MHD Flow Past a Vertical Plate Embedded in a Porous Medium

    Directory of Open Access Journals (Sweden)

    Farhad Ali

    2013-01-01

    on free convection unsteady magnetohydrodynamic (MHD flow of viscous fluid embedded in a porous medium is presented. The flow in the fluid is induced due to uniform motion of the plate. The dimensionless coupled linear partial differential equations are solved by using Laplace transform method. The solutions that have been obtained are expressed in simple forms in terms of elementary function exp(· and complementary error function erfc(·. They satisfy the governing equations; all imposed initial and boundary conditions and can immediately be reduced to their limiting solutions. The influence of various embedded flow parameters such as the Hartmann number, permeability parameter, Grashof number, dimensionless time, Prandtl number, chemical reaction parameter, Schmidt number, and Soret number is analyzed graphically. Numerical solutions for skin friction, Nusselt number, and Sherwood number are also obtained in tabular forms.

  3. Heat and Mass Transfer on Squeezing Unsteady MHD Nano fluid Flow between Parallel Plates with Slip Velocity Effect

    International Nuclear Information System (INIS)

    Singh, K.; Rawat, S. K.; Kumar, M.

    2016-01-01

    Heat and mass transfer behavior of unsteady flow of squeezing between two parallel plates in the sight of uniform magnetic field with slip velocity effect is investigated. The governing equations representing fluid flow have been transformed into nonlinear ordinary differential equations using similarity transformation. The equations thus obtained have been solved numerically using Runge-Kutta-Fehlberg method with shooting technique. Effects on the behavior of velocity, temperature, and concentration for various values of relevant parameters are illustrated graphically. The skin-friction coefficient and heat and mass transfer rate are also tabulated for various governing parameters. The results indicate that, for nano fluid flow, the rates of heat and mass transfer are inversely proportional to nanoparticle volume fraction and magnetic parameter. The rate of mass transfer increases with increasing values of Schmidt number and squeeze number.

  4. Development and validation of a CFD based methodology to estimate the pressure loss of flow through perforated plates

    International Nuclear Information System (INIS)

    Barros Filho, Jose A.; Navarro, Moyses A.; Santos, Andre A.C. dos; Jordao, E.

    2011-01-01

    In spite of the recent great development of Computational Fluid Dynamics (CFD), there are still some issues about how to assess its accurateness. This work presents the validation of a CFD methodology devised to estimate the pressure drop of water flow through perforated plates similar to the ones used in some reactor core components. This was accomplished by comparing the results of CFD simulations against experimental data of 5 perforated plates with different geometric characteristics. The proposed methodology correlates the experimental data within a range of ± 7.5%. The validation procedure recommended by the ASME Standard for Verification and Validation in Computational Fluid Dynamics and Heat Transfer-V and V 20 is also evaluated. The conclusion is that it is not adequate to this specific use. (author)

  5. Effects of Thermal Radiation and Chemical Reaction on MHD Free Convection Flow past a Flat Plate with Heat Source and Convective Surface Boundary Condition

    OpenAIRE

    E.Hemalatha; N. Bhaskar Reddy

    2015-01-01

    This paper analyzes the radiation and chemical reaction effects on MHD steady two-dimensional laminar viscous incompressible radiating boundary layer flow over a flat plate in the presence of internal heat generation and convective boundary condition. It is assumed that lower surface of the plate is in contact with a hot fluid while a stream of cold fluid flows steadily over the upper surface with a heat source that decays exponentially. The Rosseland approximation is used to desc...

  6. Flow control inside a molten Zn pot for improving surface quality of zinc plated strips

    Energy Technology Data Exchange (ETDEWEB)

    Choi, J.H. [Samsung Techwin Co., Ltd. (Korea); Koh, M.S.; Kim, S. [Pohang University of Science and Technology Graduate School, Pohang (Korea)

    2001-10-01

    The flow fields inside a molten Zn pot of continuous hot-chip galvanizing process were investigated experimentally. With varying several parameters including the strip speed V{sub s}, flow rate Q of induction heater, scrapper location and baffle configuration, instantaneous velocity fields were measured using a PIV velocity field measurement technique. Inside the strip region, counter-clockwise rotating flow is dominant. The general flow pattern inside the strip region is nearly not influenced by the trip speed V{sub 2}, flow rate Q and the scrapper location. In the exit region, the flow separated from the moving strip due to the existence of a stabilizing roll ascends to the free surface, for the cases of no scrapper and scrapper detached form the roll. On the other hand, the ascending flow to the free surface is decreased, as the flow rate Q of induction heater increases. By installing a baffle around the uprising strip, the flow moving up to the stabilizing roll decreases. In addition, B-type baffle is better than A-type baffle in reducing speed of flow around the stabilizing rolls. However, the flow ascended to the free surface is largely influenced by changing the flow rate Q, and the scrapper location, irrespective of the baffle type. (author). 14 refs., 11 figs.

  7. Comparison of Different Analytic Solutions to Axisymmetric Squeezing Fluid Flow between Two Infinite Parallel Plates with Slip Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Hamid Khan

    2012-01-01

    Full Text Available We investigate squeezing flow between two large parallel plates by transforming the basic governing equations of the first grade fluid to an ordinary nonlinear differential equation using the stream functions ur(r,z,t=(1/r(∂ψ/∂z and uz(r,z,t=−(1/r(∂ψ/∂r and a transformation ψ(r,z=r2F(z. The velocity profiles are investigated through various analytical techniques like Adomian decomposition method, new iterative method, homotopy perturbation, optimal homotopy asymptotic method, and differential transform method.

  8. Unsteady Hydromagnetic Flow of Radiating Fluid Past a Convectively Heated Vertical Plate with the Navier Slip

    Directory of Open Access Journals (Sweden)

    O. D. Makinde

    2014-01-01

    Full Text Available This paper investigates the unsteady hydromagnetic-free convection of an incompressible electrical conducting Boussinesq’s radiating fluid past a moving vertical plate in an optically thin environment with the Navier slip, viscous dissipation, and Ohmic and Newtonian heating. The nonlinear partial differential equations governing the transient problem are obtained and tackled numerically using a semidiscretization finite difference method coupled with Runge-Kutta Fehlberg integration technique. Numerical data for the local skin friction coefficient and the Nusselt number have been tabulated for various values of parametric conditions. Graphical results for the fluid velocity, temperature, skin friction, and the Nusselt number are presented and discussed. The results indicate that the skin friction coefficient decreases while the heat transfer rate at the plate surface increases as the slip parameter and Newtonian heating increase.

  9. Ionization chamber

    International Nuclear Information System (INIS)

    Jilbert, P.H.

    1975-01-01

    The invention concerns ionization chambers with particular reference to air-equivalent ionization chambers. In order to ensure that similar chambers have similar sensitivities and responses the surface of the chamber bounding the active volume carries a conducting material, which may be a colloidal graphite, arranged in the form of lines so that the area of the conducting material occupies only a small proportion of the area of said surface. (U.S.)

  10. Drag Induced by Flat-Plate Imperfections in Compressible Turbulent Flow Regimes

    OpenAIRE

    Molton , Pascal; Hue , David; Bur , Reynald

    2014-01-01

    International audience; This paper presents the results of a coupled experimental and numerical study aimed at evaluating the influence of typical aircraft surface imperfections on the flat-plate drag production in fully turbulent conditions. A test campaign involving high-level measurement techniques, such as microdrag evaluation, near-wall laser Doppler velocimetry, and oil-film interferometry, has been carried out at several Mach numbers from 0.5 to 1.3 to quantify the impact of a large ra...

  11. Study of turbulent flows loaded with particles. Application to the particulate fouling of corrugated plate heat exchangers

    International Nuclear Information System (INIS)

    Kouidri, Frederic

    1997-01-01

    This work is a numerical and experimental study of the behaviour of a turbulent flow loaded with solid particles. It involves the particulate fouling of plate heat exchangers used in industrial field. Visual observation and LDA measurements inside a mock-up show the presence of large coherent vortices and confirm the tight link between particulate deposition and flow field. The vortices participate to the creation of preferential areas where the particles are in contact with the wall, and they shape the deposit according to a precise mechanism. Two processes of deposit removal have also been shown. Hydraulic phenomena and particles behaviours pointed out in the experiment are compared to different typical samples in a bibliographic survey. The use of the a software for computational fluid dynamics (TRIO developed at the Commissariat a l'Energie Atomique) completed the experimental results by predicting the particles behaviour into the turbulent flow. The approach is based on a connection between a pseudo-direct simulation of the turbulent flow and a Lagrangian model for particles paths. The results show good agreements, qualitatively speaking, between numerical predictions and experimental measurement. The arrangement of the deposit onto the corrugated surface is globally well described by numerical simulation. The influence of some parameters on deposition process such as the flow (corresponding to Re=5000 or Re=10000), the horizontal or vertical position of the channel or the particles diameter (d p =100 μm or d p =25 μm) has been studied. (author) [fr

  12. Flow and linear coefficient of thermal expansion of four types of Base Plate waxes compared with ADA standard

    Directory of Open Access Journals (Sweden)

    Monzavi A

    2002-07-01

    Full Text Available Waxes have a lot of applications in dentistry. Such materials are of thermoplastic type that undergoes deformation in different temperatures. Two important properties of base plate waxes are flow and their coefficient of linear thermal expansion. Recently, different institutions, inside the country, produce dentistry waxes, while they have not been standardized. Consequently, consumers' dissatisfaction are observed. In this research, the two above- mentioned factors were compared between three kinds of Iranian waxes with Cavex that is foreign production, based on test number 24 of ADA. To measure the flow rate in the temperatures of 23, 37 and 45°c, Wilcoxon statistical analysis was used. The results showed that in 23°c, the flow rate of Cavex and Azardent waxes met ADA standards; however, it was not true for two others types. In 37°c, the flow of none of the waxes was standardized and in 45°c their flow was acceptable, moreover, thermal expansion coefficient, for Cavex and Azardent types, was based on ADA standard.

  13. Focused Fluid Flow along Convergent Plate Boundaries - Deriving Flow Rates along Faults from Local Upwarping of the Base of the Gas Hydrate Stability Zone

    Science.gov (United States)

    Kunath, P.; Chi, W. C.; Liu, C. S.

    2017-12-01

    Convergent plate boundaries provide the ideal opportunity to examine the interactions of deformation, fluid flow and gas hydrate stability. However, there are still processes and parameters that remain unclear or scarce. This may be in part due to the fact that in situ determination of fluid flow rate is very difficult. Here, we present a newly developed 2-D hydrothermal model for (1) simulating the steady state, thermal effect of forced heat advection along a thin and shallow dipping fault and (2) quantifying fluid velocities required to deliver a thermal anomalies manifested at the bottom-simulating reflector (BSR) at its intersection with the fault zone. Assuming the horizontal thermal conduction is negligible, we derive our model using only a few crucial parameters: (a) the thermal conductivity structure between seafloor and fault; (b) the temperature at BSR depth and the seafloor; (c) fluid flow rate; (d) geometry of the fault conduit, including depth and thickness. Temperature disturbance is then described as a function of Peclet number and of the dip of the fault. Application of our model to Site 892 at Cascadia accretionary wedge (ODP Leg 146), where borehole data provide excellent thermal constraints on the hydrology, shows consistent results. By comparing the temperatures derived at the BSRs with the temperature field of our model, the results demonstrate that the temperature discrepancy is about 0 - 0.5 oC. We propose that this simple approach can provide, on the basis of a few parameters, rough estimate of the disturbance of the temperature caused by advecting fluid. Localized lateral BSR-based heat flow variations have been observed near thrust faults along many convergent plate boundaries around the world and are associated with strong localized fluid flow. We wish to further testing this approach using other seismic datasets to estimate first order of magnitude fluid migration patterns in other convergent boundaries.

  14. Test chamber

    NARCIS (Netherlands)

    Leferink, Frank Bernardus Johannes

    2009-01-01

    A test chamber for measuring electromagnetic radiation emitted by an apparatus to be tested or for exposing an apparatus to be tested to an electromagnetic radiation field. The test chamber includes a reverberation chamber made of a conductive tent fabric. To create a statistically uniform field in

  15. Exact Solutions for Unsteady Free Convection Flow of Casson Fluid over an Oscillating Vertical Plate with Constant Wall Temperature

    Directory of Open Access Journals (Sweden)

    Asma Khalid

    2015-01-01

    Full Text Available The unsteady free flow of a Casson fluid past an oscillating vertical plate with constant wall temperature has been studied. The Casson fluid model is used to distinguish the non-Newtonian fluid behaviour. The governing partial differential equations corresponding to the momentum and energy equations are transformed into linear ordinary differential equations by using nondimensional variables. Laplace transform method is used to find the exact solutions of these equations. Expressions for shear stress in terms of skin friction and the rate of heat transfer in terms of Nusselt number are also obtained. Numerical results of velocity and temperature profiles with various values of embedded flow parameters are shown graphically and their effects are discussed in detail.

  16. Unsteady boundary layer flow and heat transfer of a Casson fluid past an oscillating vertical plate with Newtonian heating.

    Directory of Open Access Journals (Sweden)

    Abid Hussanan

    Full Text Available In this paper, the heat transfer effect on the unsteady boundary layer flow of a Casson fluid past an infinite oscillating vertical plate with Newtonian heating is investigated. The governing equations are transformed to a systems of linear partial differential equations using appropriate non-dimensional variables. The resulting equations are solved analytically by using the Laplace transform method and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that velocity decreases as Casson parameters increases and thermal boundary layer thickness increases with increasing Newtonian heating parameter.

  17. Unsteady boundary layer flow and heat transfer of a Casson fluid past an oscillating vertical plate with Newtonian heating.

    Science.gov (United States)

    Hussanan, Abid; Zuki Salleh, Mohd; Tahar, Razman Mat; Khan, Ilyas

    2014-01-01

    In this paper, the heat transfer effect on the unsteady boundary layer flow of a Casson fluid past an infinite oscillating vertical plate with Newtonian heating is investigated. The governing equations are transformed to a systems of linear partial differential equations using appropriate non-dimensional variables. The resulting equations are solved analytically by using the Laplace transform method and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that velocity decreases as Casson parameters increases and thermal boundary layer thickness increases with increasing Newtonian heating parameter.

  18. Unsteady free convection flow past a semi-infinite vertical plate with constant heat flux in water based nanofluids

    Science.gov (United States)

    Narahari, Marneni

    2018-04-01

    The unsteady free convective flow of nanofluids past a semi-infinite vertical plate with uniform heat flux has been investigated numerically. An implicit finite difference technique of Crank-Nicolson scheme has been employed to solve the governing partial differential equations. Five different types of water based nanofluids containing Cu, Ag, Al2O3, CuO and TiO2 nanoparticles are considered to study the fluid flow characteristics with various time and solid volume fraction parameters. It is found that the local as well as the average Nusselt number for nanofluids is higher than the pure fluid (water). The local skin-friction is higher for pure fluid as compared to the nanofluids. The present numerical results obtained for local Nusselt number are validated with the previously published correlation results for a limiting case and it is found that the results are in good agreement.

  19. Analysis of a fully developed laminar flow b/w two parallel plates ...

    African Journals Online (AJOL)

    ... Simulation Software Comsol Multiphysics. The flow behavior and the interaction with the boundary has been analysed. Wall no slip conditions were set for evaluation purpose. The analysis is a steady state analysis by using Incompressible Navier Stokes Model. Keywords: Steady state analysis, Velocity profile, Fluid flow.

  20. Investigation of heat transfer and fluid flow in transitional regime inside a channel with staggered plates heated by radiation for PV/T system

    International Nuclear Information System (INIS)

    Ali, Ahmed Hamza H.; Ahmed, Mahmoud; Abdel-Gaied, S.M.

    2013-01-01

    This study investigates experimentally and theoretically the effects of operating and configuration parameters on convection heat transfer process and fluid flow characteristics for air flowing in transitional regimes through parallel plate channels with staggered plates segments heated by radiant heat flux. This configuration is to be utilized in air heater solar collectors and/or in a combined photovoltaic and air heater solar collector systems (PV/T). The operating parameters tested were Reynolds number (Re) values ranging from 2580 to 4650 with a combination of incident radiation heat flux (q inc ) values of 400, 700, and 1000 W/m 2 , respectively. The experimental results show that the local Nusselt number (Nu x ) is not unique function of the axial distance, in addition, a linear relationship between Re and apparent friction factor (f) was observed. Moreover, the model results show that combination of Re values in the laminar flow regime with proper selection of both plate's length and thickness can lead to enhancement in the heat transfer from the plate segments to the air stream. This is due to self-oscillatory flow mixer in wake zone behind each plate segment. Consequently, this will lead to avoid the need of more pumping power for the case of the flow falling within the transitional regime in the channel. - Highlights: • The local heat transfer coefficient is not unique function in the axial distance. • A linear relationship between Reynolds number and apparent friction factor is observed for Re > 3500. • The plate thickness is the dominant parameter affects both values of the heat transfer and friction factor. • Shorter plates' length, at any plate thickness, leads to periodic boundary layers interruption mechanisms

  1. Rheologic effects of crystal preferred orientation in upper mantle flow near plate boundaries

    Science.gov (United States)

    Blackman, Donna; Castelnau, Olivier; Dawson, Paul; Boyce, Donald

    2016-04-01

    Observations of anisotropy provide insight into upper mantle processes. Flow-induced mineral alignment provides a link between mantle deformation patterns and seismic anisotropy. Our study focuses on the rheologic effects of crystal preferred orientation (CPO), which develops during mantle flow, in order to assess whether corresponding anisotropic viscosity could significantly impact the pattern of flow. We employ a coupled nonlinear numerical method to link CPO and the flow model via a local viscosity tensor field that quantifies the stress/strain-rate response of a textured mineral aggregate. For a given flow field, the CPO is computed along streamlines using a self-consistent texture model and is then used to update the viscosity tensor field. The new viscosity tensor field defines the local properties for the next flow computation. This iteration produces a coupled nonlinear model for which seismic signatures can be predicted. Results thus far confirm that CPO can impact flow pattern by altering rheology in directionally-dependent ways, particularly in regions of high flow gradient. Multiple iterations run for an initial, linear stress/strain-rate case (power law exponent n=1) converge to a flow field and CPO distribution that are modestly different from the reference, scalar viscosity case. Upwelling rates directly below the spreading axis are slightly reduced and flow is focused somewhat toward the axis. Predicted seismic anisotropy differences are modest. P-wave anisotropy is a few percent greater in the flow 'corner', near the spreading axis, below the lithosphere and extending 40-100 km off axis. Predicted S-wave splitting differences would be below seafloor measurement limits. Calculations with non-linear stress/strain-rate relation, which is more realistic for olivine, indicate that effects are stronger than for the linear case. For n=2-3, the distribution and strength of CPO for the first iteration are greater than for n=1, although the fast seismic

  2. Transmission of heat from a flat plate to a fluid flowing at a high velocity

    Science.gov (United States)

    Crocco, Luigi

    1932-01-01

    The writer, starting with the consideration of the hydrodynamic and thermodynamic equations for the turbulent boundary layer of a flat plate when it is necessary to take into account the heat produced by friction, arrives at the conclusion that the transmission of the heat follows the same law that is valid when the frictional heat is negligible, provided the temperature of the fluid is considered to be that which the fluid would reach if arrested adiabatically. It is then shown how the same law holds good for faired bodies, and some applications of the law are made to the problems of flight at very high speeds.

  3. Numerical analysis on interactions between fluid flow and structure deformation in plate-fin heat exchanger by Galerkin method

    Science.gov (United States)

    Liu, Jing-cheng; Wei, Xiu-ting; Zhou, Zhi-yong; Wei, Zhen-wen

    2018-03-01

    The fluid-structure interaction performance of plate-fin heat exchanger (PFHE) with serrated fins in large scale air-separation equipment was investigated in this paper. The stress and deformation of fins were analyzed, besides, the interaction equations were deduced by Galerkin method. The governing equations of fluid flow and heat transfer in PFHE were deduced by finite volume method (FVM). The distribution of strain and stress were calculated in large scale air separation equipment and the coupling situation of serrated fins under laminar situation was analyzed. The results indicated that the interactions between fins and fluid flow in the exchanger have significant impacts on heat transfer enhancement, meanwhile, the strain and stress of fins includes dynamic pressure of the sealing head and flow impact with the increase of flow velocity. The impacts are especially significant at the conjunction of two fins because of the non-alignment fins. It can be concluded that the soldering process and channel width led to structure deformation of fins in the exchanger, and degraded heat transfer efficiency.

  4. The Carrier Gas Pressure Effect in a Laminar Flow Diffusion Chamber, Homogeneous Nucleation of n-Butanol in Helium

    Czech Academy of Sciences Publication Activity Database

    Hyvärinen, A-P.; Brus, David; Ždímal, Vladimír; Smolík, Jiří; Kulmala, M.; Viisanen, V.; Lihavainen, H.

    2006-01-01

    Roč. 124, č. 22 (2006), Art. No. 224304 ISSN 0021-9606 R&D Projects: GA AV ČR(CZ) IAA2076203 Institutional research plan: CEZ:AV0Z40720504 Keywords : supersaturated vapor * cloud chamber * background gas es Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.166, year: 2006

  5. Method of producing exfoliated graphite composite compositions for fuel cell flow field plates

    Energy Technology Data Exchange (ETDEWEB)

    Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z

    2014-04-08

    A method of producing an electrically conductive composite composition, which is particularly useful for fuel cell bipolar plate applications. The method comprises: (a) providing a supply of expandable graphite powder; (b) providing a supply of a non-expandable powder component comprising a binder or matrix material; (c) blending the expandable graphite with the non-expandable powder component to form a powder mixture wherein the non-expandable powder component is in the amount of between 3% and 60% by weight based on the total weight of the powder mixture; (d) exposing the powder mixture to a temperature sufficient for exfoliating the expandable graphite to obtain a compressible mixture comprising expanded graphite worms and the non-expandable component; (e) compressing the compressible mixture at a pressure within the range of from about 5 psi to about 50,000 psi in predetermined directions into predetermined forms of cohered graphite composite compact; and (f) treating the so-formed cohered graphite composite to activate the binder or matrix material thereby promoting adhesion within the compact to produce the desired composite composition. Preferably, the non-expandable powder component further comprises an isotropy-promoting agent such as non-expandable graphite particles. Further preferably, step (e) comprises compressing the mixture in at least two directions. The method leads to composite plates with exceptionally high thickness-direction electrical conductivity.

  6. Nonisothermal flow of a non-Newtonian fluid with viscous heating between two parallel plates

    International Nuclear Information System (INIS)

    Imal, M.; Pinarbasi, A.

    2004-01-01

    In this study the pressure gradient-flow rate relationship for steady-state nonisothermal pressure-driven flow of a non-Newtonian fluid in a channel is investigated including the effect of viscous heating is taken into account. The viscosity of the fluid depends on both temperature and shear-rate. Exponential dependence of viscosity on temperature is modelled through Arrhenius law. Non-Newtonian behaviour of the fluid is modelled according to the Carreau rheological equation, which reflects the characteristics of most polymers adequately with an exponential temperature dependence of viscosity. Flow governing motion and energy balance equations are coupled and solution of this non-linear boundary value problem is found iteratively using a pseudo spectral method based on Chebyshev polynomials. The effect of activation energy parameter and Brinkman number, as well as the power-law index and material time constant on the flow is studied. It is found that while the pressure gradient-flow rate graph is monotonic for certain ranges of flow controlling parameters, there is a large jump in the graph under certain values of these parameters.(1 table and 5 figures are included.)

  7. Large-scale dynamics in the flow around a finite cylinder with a ground plate

    International Nuclear Information System (INIS)

    Frederich, Octavian; Scouten, Jon; Luchtenburg, Dirk M; Thiele, Frank

    2011-01-01

    To date, physically meaningful representations of the nonstationarity in complex 3D flows with converged turbulent statistics are scarce and shed little light on the nonlinear processes in turbulent motion. This study attempts to address part of this deficit by concentrating on the kinematics of larger scales of motion. Two methods are utilized to describe the kinematics of large-scale unsteady motion in the flow around a wall-mounted finite circular cylinder at Reynolds number Re D = 200 000. The first, Proper Orthogonal Decomposition (POD), is a global method resulting in spatial modes defined over the whole domain and their corresponding temporal coefficients. The second, Coherent Structure Tracking (CST), belongs to a class of local methods that extracts connected domains in the flow data. Modes specific for distinct harmonics are extracted by temporal harmonic filtering. Based on time coefficients of the dominant mode pairs provided by POD or harmonic filtering, phase-averaging has been performed. A scalar-field version of CST is proposed, yielding an intuitively more accessible description of the flow. The extent to which POD and CST are complementary is discussed, as well as the extent to which they partially overlap. The combination of POD, filtering, phase-averaging and CST allowed for identification and quantification of important flow patterns in a complex turbulent flow field.

  8. Thermal-hydraulic analysis under partial loss of flow accident hypothesis of a plate-type fuel surrounded by two water channels using RELAP5 code

    Directory of Open Access Journals (Sweden)

    Itamar Iliuk

    2016-01-01

    Full Text Available Thermal-hydraulic analysis of plate-type fuel has great importance to the establishment of safety criteria, also to the licensing of the future nuclear reactor with the objective of propelling the Brazilian nuclear submarine. In this work, an analysis of a single plate-type fuel surrounding by two water channels was performed using the RELAP5 thermal-hydraulic code. To realize the simulations, a plate-type fuel with the meat of uranium dioxide sandwiched between two Zircaloy-4 plates was proposed. A partial loss of flow accident was simulated to show the behavior of the model under this type of accident. The results show that the critical heat flux was detected in the central region along the axial direction of the plate when the right water channel was blocked.

  9. Numerical simulation of reacting and non-reacting flow in a combustion chamber; Numerisk simulering av reagerande och icke-reagerande stroemning i en braennkammare

    Energy Technology Data Exchange (ETDEWEB)

    Borg, A.; Revstedt, J.

    1996-04-01

    The purpose of this work has been to do a preliminary study of how well numerical calculations with different turbulence models can predict the flow and temperature fields of a strongly swirling and combusting flow in an experimental combustion chamber and to see which parameters in the mathematical model are the most important. The combustion chamber on which we have done the calculations is called Validation Rig II and was designed by Volvo Aero Corporation. The main part of the study has been carried out on a non-reacting flow but some work has also been done on reacting flow. In most cases it has not been meaningful to compare the calculations with the measurements because they differ quite a lot from each other. For the non-reacting case the following investigations have been made: * How the solution differs for different turbulence models, * The solutions sensitivity to inlet boundary conditions, * How different types of leakage disturb the flow, and * The difference in results between two different CFD-codes, the commercial code CFDS-Flow3D and a code developed at the department of fluid mechanics. For the reacting cases we have studied the influence of: * one or two reaction steps, * the effects of a change in reaction rate, * the influence of thermal radiation, and * the effects of changing the boundary conditions for temperature on the walls. The results from these calculations show that the inlet turbulence intensity has very little effect on the values of the turbulent quantities as well as the velocity profiles at the outlet. Changing the turbulence model or the outlet boundary conditions gives some change in velocity profiles at the outlet but only marginal effects on the swirl number. 21 refs, 54 figs, 19 tabs

  10. Numerical Study of Wavy Film Flow on Vertical Plate Using Different Turbulent Models

    International Nuclear Information System (INIS)

    Min, June Kee; Park, Il Seouk

    2014-01-01

    Film flows applied to shell-and-tube heat exchangers in various industrial fields have been studied for a long time. One boundary of the film flow interfaces with a fixed wall, and the other boundary interfaces with a gaseous region. Thus, the flows become so unstable that wavy behaviors are generated on free surfaces as the film Reynolds number increases. First, high-amplitude solitary waves are detected in a low Reynolds number laminar region; then, the waves transit to a low-amplitude, high frequency ripple in a turbulent region. Film thickness is the most significant factor governing heat transfer. Since the wave accompanied in the film flow results in temporal and spatial variations in film thickness, it can be of importance for numerically predicting the film's wavy behavior. In this study, various turbulent models are applied for predicting low-amplitude ripple flows in turbulent regions. The results are compared with existing experimental results, and finally, the applied turbulent models are appraised in from the viewpoint of wavy behaviors

  11. Numerical Study of Wavy Film Flow on Vertical Plate Using Different Turbulent Models

    Energy Technology Data Exchange (ETDEWEB)

    Min, June Kee [Pusan National University, Busan (Korea, Republic of); Park, Il Seouk [Kyungpook National University, Daegu (Korea, Republic of)

    2014-05-15

    Film flows applied to shell-and-tube heat exchangers in various industrial fields have been studied for a long time. One boundary of the film flow interfaces with a fixed wall, and the other boundary interfaces with a gaseous region. Thus, the flows become so unstable that wavy behaviors are generated on free surfaces as the film Reynolds number increases. First, high-amplitude solitary waves are detected in a low Reynolds number laminar region; then, the waves transit to a low-amplitude, high frequency ripple in a turbulent region. Film thickness is the most significant factor governing heat transfer. Since the wave accompanied in the film flow results in temporal and spatial variations in film thickness, it can be of importance for numerically predicting the film's wavy behavior. In this study, various turbulent models are applied for predicting low-amplitude ripple flows in turbulent regions. The results are compared with existing experimental results, and finally, the applied turbulent models are appraised in from the viewpoint of wavy behaviors.

  12. Aligned Magnetic Field, Radiation, and Rotation Effects on Unsteady Hydromagnetic Free Convection Flow Past an Impulsively Moving Vertical Plate in a Porous Medium

    Directory of Open Access Journals (Sweden)

    Sandeep Naramgari

    2014-01-01

    Full Text Available We analyse the effects of aligned magnetic field, radiation, and rotation on unsteady hydromagnetic free convection flow of a viscous incompressible electrically conducting fluid past an impulsively moving vertical plate in a porous medium in presence of heat source. An exact solution of the governing equations in dimensionless form is obtained by Laplace transform technique in ramped temperature case. To compare the results obtained in this case with that of isothermal plate, the exact solution of the governing equations is also obtained for isothermal plate and results are discussed graphically in both ramped temperature and isothermal cases.

  13. Hydromagnetic natural convection flow between vertical parallel plates with time-periodic boundary conditions

    International Nuclear Information System (INIS)

    Adesanya, S.O.; Oluwadare, E.O.; Falade, J.A.; Makinde, O.D.

    2015-01-01

    In this paper, the free convective flow of magnetohydrodynamic fluid through a channel with time periodic boundary condition is investigated by taking the effects of Joule dissipation into consideration. Based on simplifying assumptions, the coupled governing equations are reduced to a set of nonlinear boundary valued problem. Approximate solutions are obtained by using semi-analytical Adomian decomposition method. The effect of pertinent parameters on the fluid velocity, temperature distribution, Nusselt number and skin friction are presented graphically and discussed. The result of the computation shows that an increase in the magnetic field intensity has significant influence on the fluid flow. - Highlights: • The influence of magnetic field on the free convective fluid flow is considered. • The coupled equations are solved by using Adomian decomposition method. • The Adomian series solution agreed with previously obtained result. • Magnetic field decreases the velocity maximum but enhances temperature field

  14. A heat transfer analysis of laminar flow over a flat plate with unheated starting region for low Prandtl number fluids

    International Nuclear Information System (INIS)

    Ahola, M.P.; Karimi, A.

    1996-01-01

    In boundary layer analyses involving heat transfer, the Prandtl number (Pr) relates the diffusion of momentum to the diffusion of heat, and can be shown to directly correlate to the ratio of the thermal boundary layer thickness to the velocity boundary layer thickness. For large Prandtl number fluids (i.e., Pr > 1) the velocity boundary layer thickness is larger than the thermal boundary layer thickness, and vice versa. In some applications in the industry heating does not occur over the entire plate, such as in the case of an unheated starting region or spot heating along a finite segment of the plate. For such applications solutions only exist for the simpler case of large Prandtl number fluids where the thermal boundary layer is assumed to be smaller than the velocity boundary layer. The analyses presented in this paper extends the solution to the unheated starting region problem for small Prandtl number fluids, where the thermal boundary layer grows larger and crosses the velocity boundary layer. The solution is based on the integral method approach assuming laminar flow, and both cases of constant wall temperature as well as constant wall heat flux are analyzed

  15. Confocal microscopy of colloidal dispersions in shear flow using a counter-rotating cone-plate shear cell

    International Nuclear Information System (INIS)

    Derks, Didi; Wisman, Hans; Blaaderen, Alfons van; Imhof, Arnout

    2004-01-01

    We report on novel possibilities for studying colloidal suspensions in a steady shear field in real space. Fluorescence confocal microscopy is combined with the use of a counter-rotating cone-plate shear cell. This allows imaging of individual particles in the bulk of a sheared suspension in a stationary plane. Moreover, this plane of zero velocity can be moved in the velocity gradient direction while keeping the shear rate constant. The colloidal system under study consists of rhodamine labelled PMMA spheres in a nearly density and refractive index matched mixture of cyclohexylbromide and cis-decalin. We show measured flow profiles in both the fluid and the crystalline phase and find indications for shear banding in the case of a sheared crystal. Furthermore, we show that, thanks to the counter-rotating principle of the cone-plate shear cell, a layer of particles in the bulk of a sheared crystalline suspension can be imaged for a prolonged time, with the result that their positions can be tracked

  16. LES with acoustics and FSI for deforming plates in gas flow

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, Per, E-mail: pnilsson@tuv-nord.com [European Spallation Source, Lund (Sweden); Lillberg, Eric [Westinghouse, Vaesteras (Sweden); Wikstroem, Niklas [FS Dynamics, Stockholm (Sweden)

    2012-12-15

    This concerns Flow Induced Vibrations (FIV) in nuclear reactors and numerical analysis of such. Special attention is paid to structural excitation by sound generated remotely and turbulent flow around the structure. One hypothesis was that these phenomena can interact, so that the structure accumulates more energy from the flow if it also excited by sound from another source. In the studies, Fluid-Structure Interaction (FSI) is simulated with Large Eddy Simulations (LESs). It is shown possible to simulate excitation due to both acoustic and turbulence loads using the reported methods, at least qualitatively. The excitation levels are even of the right order of magnitude in some parts. However, there are some shortcomings in the modeling. The most important is perhaps the lack of non-reflecting boundary conditions. Another problem is the strong numerical damping in combination with demanding numerics for the selected solid solution methodology. Three cases are simulated, two for validation and one applied about steam dryers. For the applied case, it is concluded unlikely that excitation by the acoustic and turbulence loads can interact. The main reason is that the flow is controlled more by static geometrical factors, such as solid rotation sharp edges, than small deformations due to vibrations.

  17. Flow patterns and heat transfer characteristics of flat plate pulsating heat pipes with various asymmetric and aspect ratios of the channels

    International Nuclear Information System (INIS)

    Jang, Dong Soo; Lee, Joo Seong; Ahn, Jae Hwan; Kim, Dongwoo; Kim, Yongchan

    2017-01-01

    Highlights: • Flat plate pulsating heat pipes with asymmetric and aspect ratios were tested. • Flow patterns were investigated according to channel geometry and flow condition. • Heat transfer characteristics were analyzed with various heat inputs. • Optimum asymmetric and aspect ratios were suggested for maximum thermal performance. - Abstract: The thermal performance of flat plate pulsating heat pipes (PHPs) in compact electronic devices can be improved by adopting asymmetric channels with increased pressure differences and an unbalanced driving force. The objective of this study is to investigate the heat transfer characteristics of flat plate PHPs with various asymmetric ratios and aspect ratios in the channels. The thermal performance and flow pattern of the flat plate PHPs were measured by varying the asymmetric ratio from 1.0 to 4.0, aspect ratio from 2.5 to 5.0, and heat input from 2 to 28 W. The effects of the asymmetric ratio and aspect ratio on the thermal resistance were analyzed with the measured evaporator temperature and flow patterns at various heat inputs. With heat inputs of 6 W and 12 W, the optimum asymmetric ratio and aspect ratio for the flat plate PHPs were determined to be 4.0 and 2.5, respectively. With the heat input of 18 W, the optimum asymmetric ratio and aspect ratio were determined to be 1.5 and 2.5, respectively.

  18. Unsteady MHD free convection flow of casson fluid over an inclined vertical plate embedded in a porous media

    Science.gov (United States)

    Manideep, P.; Raju, R. Srinivasa; Rao, T. Siva Nageswar; Reddy, G. Jithender

    2018-05-01

    This paper deals, an unsteady magnetohydrodynamic heat transfer natural convection flow of non-Newtonian Casson fluid over an inclined vertical plate embedded in a porous media with the presence of boundary conditions such as oscillating velocity, constant wall temperature. The governing dimensionless boundary layer partial differential equations are reduced to simultaneous algebraic linear equation for velocity, temperature of Casson fluid through finite element method. Those equations are solved by Thomas algorithm after imposing the boundary conditions through MATLAB for analyzing the behavior of Casson fluid velocity and temperature with various physical parameters. Also analyzed the local skin-friction and rate of heat transfer. Compared the present results with earlier reported studies, the results are comprehensively authenticated and robust FEM.

  19. Thermal radiation and mass transfer effects on unsteady MHD free convection flow past a vertical oscillating plate

    Science.gov (United States)

    Rana, B. M. Jewel; Ahmed, Rubel; Ahmmed, S. F.

    2017-06-01

    Unsteady MHD free convection flow past a vertical porous plate in porous medium with radiation, diffusion thermo, thermal diffusion and heat source are analyzed. The governing non-linear, partial differential equations are transformed into dimensionless by using non-dimensional quantities. Then the resultant dimensionless equations are solved numerically by applying an efficient, accurate and conditionally stable finite difference scheme of explicit type with the help of a computer programming language Compaq Visual Fortran. The stability and convergence analysis has been carried out to establish the effect of velocity, temperature, concentration, skin friction, Nusselt number, Sherwood number, stream lines and isotherms line. Finally, the effects of various parameters are presented graphically and discussed qualitatively.

  20. Experimental study of oscillating plates in viscous fluids: Qualitative and quantitative analysis of the flow physics and hydrodynamic forces

    Science.gov (United States)

    Shrestha, Bishwash; Ahsan, Syed N.; Aureli, Matteo

    2018-01-01

    In this paper, we present a comprehensive experimental study on harmonic oscillations of a submerged rigid plate in a quiescent, incompressible, Newtonian, viscous fluid. The fluid-structure interaction problem is analyzed from both qualitative and quantitative perspectives via a detailed particle image velocimetry (PIV) experimental campaign conducted over a broad range of oscillation frequency and amplitude parameters. Our primary goal is to identify the effect of the oscillation characteristics on the mechanisms of fluid-structure interaction and on the dynamics of vortex shedding and convection and to elucidate the behavior of hydrodynamic forces on the oscillating structure. Towards this goal, we study the flow in terms of qualitative aspects of its pathlines, vortex shedding, and symmetry breaking phenomena and identify distinct hydrodynamic regimes in the vicinity of the oscillating structure. Based on these experimental observations, we produce a novel phase diagram detailing the occurrence of distinct hydrodynamic regimes as a function of relevant governing nondimensional parameters. We further study the hydrodynamic forces associated with each regime using both PIV and direct force measurement via a load cell. Our quantitative results on experimental estimation of hydrodynamic forces show good agreement against predictions from the literature, where numerical and semi-analytical models are available. The findings and observations in this work shed light on the relationship between flow physics, vortex shedding, and convection mechanisms and the hydrodynamic forces acting on a rigid oscillating plate and, as such, have relevance to various engineering applications, including energy harvesting devices, biomimetic robotic system, and micro-mechanical sensors and actuators.

  1. Ussing Chamber

    NARCIS (Netherlands)

    Westerhout, J.; Wortelboer, H.; Verhoeckx, K.

    2015-01-01

    The Ussing chamber system is named after the Danish zoologist Hans Ussing, who invented the device in the 1950s to measure the short-circuit current as an indicator of net ion transport taking place across frog skin (Ussing and Zerahn, Acta Physiol Scand 23:110-127, 1951). Ussing chambers are

  2. Mathematical Model for Fluid Flow and Heat Transfer Processes in Plate Exchanger

    Directory of Open Access Journals (Sweden)

    Cvete B. Dimitrieska

    2015-11-01

    Full Text Available Within the analytical solution of the system of equations which solve fluid flow and heat transfer processes, the elliptical and parabolic differential equations based on initial and boundary conditions is usually unfamiliar in a closed form. Numerical solution of equation system is necessarily obtained by discretization of equations. When system of equations relate to estimation of two dimensional stationary problems, the applicable method for estimation in basic two – dimensional form is recommended.

  3. A study of flow performance and flooding in pulsed sieve plate extraction columns

    International Nuclear Information System (INIS)

    Zhang Quanrong; Wang Ruipian

    1986-01-01

    The pulsed sieve plate extraction columns could be divided into two types. The type II which has larger coalescence-damping coefficient K has an apparent transition region that widens when the K value has been increased. In this time, the operation condition in the column of type II is very different from that of type I. The flooding could be divided into three types: the flooding due to insufficient pulsing; emulsion flooding; and flooding due to dispersed phase and continuous phase that replace each other. The three kinds of flooding in the column of type II are very different from that in the column of type I. In the column of type II, when the value of K is about 2 to 3, emulsion flooding has occured and flooding capacity is the largest. In that column. The largest flooding capacity is usually larger than 1300 l/dm 2 · hr when the system 30% TBP(OK)-HNO 3 is used, but it cannot be used under normal conditions when the K value is larger

  4. wire chamber

    CERN Multimedia

    Proportional multi-wire chamber. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle. Proportional wire chambers allow a much quicker reading than the optical or magnetoscriptive readout wire chambers.

  5. Effects of oxygen gas flow rates and Ga contents on structural properties of Ga-doped ZnO films prepared by ion-plating with a DC arc discharge

    International Nuclear Information System (INIS)

    Terasako, Tomoaki; Nomoto, Junichi; Makino, Hisao; Yamamoto, Naoki; Shirakata, Sho; Yamamoto, Tetsuya

    2015-01-01

    Structural properties of highly c-axis oriented polycrystalline Ga-doped ZnO (GZO) films prepared by ion-plating with a DC arc discharge were studied in terms of the oxygen gas flow rate (F O2 ) introduced into the chamber during the deposition process and the Ga 2 O 3 content in the GZO sintered pellet. The X-ray diffraction (XRD) measurements revealed that the GZO films have the residual compressive stress along the a-axis direction (in-plane) and the tensile stress along the c-axis direction (out-of-plane). The increase in F O2 or the increase in Ga 2 O 3 content was effective for relaxing the in-plane compressive stress induced by the so-called atomic peening effect. The positive correlation between the carrier concentration (n) and the primitive cell volume (V) would be due to the incorporation of Ga atoms substituting Zn sites (Ga Zn s) together with the generation of n-type intrinsic defects or complex defects. - Highlights: • Films of Ga-doped ZnO (GZO) films were deposited by ion-plating with a DC arc discharge. • Structural properties of GZO films were examined by X-ray diffraction measurements. • GZO films had the residual compressive stress along the a-axis direction. • There was the correlation between the carrier concentration and the cell volume.

  6. Effects of oxygen gas flow rates and Ga contents on structural properties of Ga-doped ZnO films prepared by ion-plating with a DC arc discharge

    Energy Technology Data Exchange (ETDEWEB)

    Terasako, Tomoaki, E-mail: terasako.tomoaki.mz@ehime-u.ac.jp [Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama-shi, Ehime 790-8577 (Japan); Nomoto, Junichi; Makino, Hisao; Yamamoto, Naoki [Research Institute, Kochi University of Technology, 185 Miyanokuchi, Tosayamada-cho, Kami-shi, Kochi 782-8502 (Japan); Shirakata, Sho [Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama-shi, Ehime 790-8577 (Japan); Yamamoto, Tetsuya [Research Institute, Kochi University of Technology, 185 Miyanokuchi, Tosayamada-cho, Kami-shi, Kochi 782-8502 (Japan)

    2015-12-01

    Structural properties of highly c-axis oriented polycrystalline Ga-doped ZnO (GZO) films prepared by ion-plating with a DC arc discharge were studied in terms of the oxygen gas flow rate (F{sub O2}) introduced into the chamber during the deposition process and the Ga{sub 2}O{sub 3} content in the GZO sintered pellet. The X-ray diffraction (XRD) measurements revealed that the GZO films have the residual compressive stress along the a-axis direction (in-plane) and the tensile stress along the c-axis direction (out-of-plane). The increase in F{sub O2} or the increase in Ga{sub 2}O{sub 3} content was effective for relaxing the in-plane compressive stress induced by the so-called atomic peening effect. The positive correlation between the carrier concentration (n) and the primitive cell volume (V) would be due to the incorporation of Ga atoms substituting Zn sites (Ga{sub Zn}s) together with the generation of n-type intrinsic defects or complex defects. - Highlights: • Films of Ga-doped ZnO (GZO) films were deposited by ion-plating with a DC arc discharge. • Structural properties of GZO films were examined by X-ray diffraction measurements. • GZO films had the residual compressive stress along the a-axis direction. • There was the correlation between the carrier concentration and the cell volume.

  7. Chamber for Aerosol Deposition of Bioparticles

    Science.gov (United States)

    Kern, Roger; Kirschner, Larry

    2008-01-01

    Laboratory apparatus is depicted that is a chamber for aerosol deposition of bioparticles on surfaces of test coupons. It is designed for primary use in inoculating both flat and three-dimensional objects with approximately reproducible, uniform dispersions of bacterial spores of the genus Bacillus so that the objects could be used as standards for removal of the spores by quantitative surface sampling and/or cleaning processes. The apparatus is also designed for deposition of particles other than bacterial spores, including fungal spores, viruses, bacteriophages, and standard micron-sized beads. The novelty of the apparatus lies in the combination of a controllable nebulization system with a settling chamber large enough to contain a significant number of test coupons. Several companies market other nebulizer systems, but none are known to include chambers for deposition of bioparticles to mimic the natural fallout of bioparticles. The nebulization system is an expanded and improved version of commercially available aerosol generators that include nebulizers and drying columns. In comparison with a typical commercial aerosol generator, this system includes additional, higher-resolution flowmeters and an additional pressure regulator. Also, unlike a typical commercial aerosol generator, it includes stopcocks for separately controlling flows of gases to the nebulizer and drying column. To maximize the degree of uniformity of dispersion of bioaerosol, the chamber is shaped as an axisymmetrical cylinder and the aerosol generator is positioned centrally within the chamber and aimed upward like a fountain. In order to minimize electric charge associated with the aerosol particles, the drying column is made of aluminum, the drying column is in direct contact with an aluminum base plate, and three equally spaced Po-210 antistatic strips are located at the exit end of the drying column. The sides and top of the chamber are made of an acrylic polymer; to prevent

  8. Numerical Study of Thermal and Flow Characteristics of Plate-Fin Heat Sink with Longitudinal Vortex Generator Installed on the Ground

    Directory of Open Access Journals (Sweden)

    Yen-Tso Chang

    2014-01-01

    Full Text Available This study applied the commercial software ANSYS CFD (FLUENT, for simulating the transient flow field and investigating the influence of each parameter of longitudinal vortex generators (LVGs on the thermal flux of a plate-fin heat sink. Vortex generator was set in front of plate-fin heat sink and under the channel, which was in common-flow-down (CFD and common-flow-up (CFU conditions, which have the result of vortex generator of delta winglet pair (DWP. In this study the parameters were varied, such as the minimum transverse distance between winglet pair, the attack angle of the vortex generator, fins number, the fin height, and the distance between the vortex generator and plate-fin. The coolant fluid flew into the fin-to-fin channel and pushed the vortex from different geometry toward the bottom. This phenomenon took off the heat from the plate to enhance the heat transfer. The numerical results indicated that the LVGs located close to the plate-fin heat sink are zero with the attack angle being 30°, presenting optimal overall conditions.

  9. The passive control of three-dimensional flow over a square cylinder by a vertical plate at a moderate Reynolds number

    Energy Technology Data Exchange (ETDEWEB)

    Malekzadeh, S; Mirzaee, I; Pourmahmoud, N [Department of Mechanical Engineering, Urmia University, Urmia (Iran, Islamic Republic of); Shirvani, H, E-mail: s.malekzadeh.d@gmail.com [Department of Computing Science, Faculty of Science and Technology, Anglia Ruskin University, Chelmsford (United Kingdom)

    2017-04-15

    This paper presents three-dimensional simulation results to investigate the reduction of fluid forces acting on a square cylinder by a passive control method, i.e. placing a vertical control plate upstream of the cylinder. The simulations were carried out for Re{sub W}  = 500, based on the width of the square cylinder (W) and the inlet flow velocity. The width of the control plate (h) varied between 0.1 W and 0.9 W and the distance between the control plate and cylinder (S) was set in the range of 1.1 W –5 W. The flow patterns, vortex shedding frequency, and wake vorticity structures were studied to determine the flow instabilities that existed over the square cylinder and control plate. In addition, the reduction of mean and fluctuating fluid forces acting on the square cylinder in the presence of a control plate was studied, and compared with the single square cylinder in order to identify optimum conditions. The results indicated that the case with h  = 0.7 W and 2.5 W  ≤  S  ≤ 3 W emerged as optimal, offering the highest reduction in the fluid forces that occurred over the square cylinder. (paper)

  10. Gridded ionization chamber

    International Nuclear Information System (INIS)

    Houston, J.M.

    1977-01-01

    An improved ionization chamber type x-ray detector comprises a heavy gas at high pressure disposed between an anode and a cathode. An open grid structure is disposed adjacent the anode and is maintained at a voltsge intermediate between the cathode and anode potentials. The electric field which is produced by positive ions drifting toward the cathode is thus shielded from the anode. Current measuring circuits connected to the anode are, therefore, responsive only to electron current flow within the chamber and the recovery time of the chamber is shortened. The grid structure also serves to shield the anode from electrical currents which might otherwise be induced by mechanical vibrations in the ionization chamber structure

  11. Instability of a binary liquid film flowing down a slippery heated plate

    Science.gov (United States)

    Ellaban, E.; Pascal, J. P.; D'Alessio, S. J. D.

    2017-09-01

    In this paper, we study the stability of a binary liquid film flowing down a heated slippery inclined surface. It is assumed that the heating induces concentration differences in the liquid mixture (Soret effect), which together with the differences in temperature affects the surface tension. A mathematical model is constructed by coupling the Navier-Stokes equations governing the flow with equations for the concentration and temperature. A Navier slip condition is applied at the liquid-solid interface. We carry out a linear stability analysis in order to obtain the critical conditions for the onset of instability. We use a Chebyshev spectral collocation method to obtain numerical solutions to the resulting Orr-Sommerfeld-type equations. We also obtain an asymptotic solution that yields an expression for the state of neutral stability of long perturbations as a function of the parameters controlling the problem. A weighted residual approximation is employed to derive a reduced model that is used to analyse the nonlinear effects. Good agreement between the linear stability analysis and nonlinear simulations provided by the weighted residual model is found.

  12. Transient radiative hydromagnetic free convection flow past an impulsively started vertical plate with uniform heat and mass flux

    Directory of Open Access Journals (Sweden)

    Prasad Ramachandra V.

    2006-01-01

    Full Text Available The interaction of free convection with thermal radiation of viscous incompressible MHD unsteady flow past an impulsively started vertical plate with uniform heat and mass flux is analyzed. This type of problem finds application in many technological and engineering fields such as rocket propulsion systems, space craft re-entry aerothermodynamics, cosmical flight aerodynamics, plasma physics, glass production and furnace engineering .The Rosseland approximation is used to describe the radiative heat transfer in the limit of the optically thin fluid. The non-linear, coupled equations are solved using an implicit finite difference scheme of Crank-Nicolson type. Velocity, temperature and concentration of the flow have been presented for various parameters such as thermal Grashof number, mass Grashof number, Prandtl number, Schmidt number, radiation parameter and magnetic parameter. The local and average skin friction, Nusslet number and Sherwood number are also presented graphically. It is observed that, when the radiation parameter increases the velocity and temperature decrease in the boundary layer. .

  13. Lie Group Solution for Free Convective Flow of a Nanofluid Past a Chemically Reacting Horizontal Plate in a Porous Media

    Directory of Open Access Journals (Sweden)

    M. M. Rashidi

    2014-01-01

    Full Text Available The optimal homotopy analysis method (OHAM is employed to investigate the steady laminar incompressible free convective flow of a nanofluid past a chemically reacting upward facing horizontal plate in a porous medium taking into account heat generation/absorption and the thermal slip boundary condition. Using similarity transformations developed by Lie group analysis, the continuity, momentum, energy, and nanoparticle volume fraction equations are transformed into a set of coupled similarity equations. The OHAM solutions are obtained and verified by numerical results using a Runge-Kutta-Fehlberg fourth-fifth order method. The effect of the emerging flow controlling parameters on the dimensionless velocity, temperature, and nanoparticle volume fraction have been presented graphically and discussed. Good agreement is found between analytical and numerical results of the present paper with published results. This close agreement supports our analysis and the accuracy of the numerical computations. This paper also includes a representative set of numerical results for reduced Nusselt and Sherwood numbers in a table for various values of the parameters. It is concluded that the reduced Nusselt number increases with the Lewis number and reaction parameter whist it decreases with the order of the chemical reaction, thermal slip, and generation parameters.

  14. Drift chamber

    International Nuclear Information System (INIS)

    Inagaki, Yosuke

    1977-01-01

    Drift chamber is becoming an important detector in high energy physics as a precision and fast position detector because of its high spatial resolution and count-rate. The basic principle is that it utilizes the drift at constant speed of electrons ionized along the tracks of charged particles towards the anode wire in the nearly uniform electric field. The method of measuring drift time includes the analog and digital ones. This report describes about the construction of and the application of electric field to the drift chamber, mathematical analysis on the electric field and equipotential curve, derivation of spatial resolution and the factor for its determination, and selection of gas to be used. The performance test of the chamber was carried out using a small test chamber, the collimated β source of Sr-90, and 500 MeV/C electron beam from the 1.3 GeV electron synchrotron in the Institute of Nuclear Study, University of Tokyo. Most chambers to date adopted one dimensional read-out, but it is very advantageous if the two dimensional read-out is feasible with one chamber when the resolution in that direction is low. The typical methods of delay line and charge division for two dimensional read-out are described. The development of digital read-out system is underway, which can process the signal of a large scale drift chamber at high speed. (Wakatsuki, Y.)

  15. Wire Chamber

    CERN Multimedia

    Magnetoscriptive readout wire chamber. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  16. Wire chamber

    CERN Multimedia

    1967-01-01

    Magnetoscriptive readout wire chamber.Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  17. Modified rational Legendre approach to laminar viscous flow over a semi-infinite flat plate

    International Nuclear Information System (INIS)

    Tajvidi, T.; Razzaghi, M.; Dehghan, M.

    2008-01-01

    A numerical method for solving the classical Blasius' equation is proposed. The Blasius' equation is a third order nonlinear ordinary differential equation , which arises in the problem of the two-dimensional laminar viscous flow over a semi-infinite flat plane. The approach is based on a modified rational Legendre tau method. The operational matrices for the derivative and product of the modified rational Legendre functions are presented. These matrices together with the tau method are utilized to reduce the solution of Blasius' equation to the solution of a system of algebraic equations. A numerical evaluation is included to demonstrate the validity and applicability of the method and a comparison is made with existing results

  18. Linear temporal and spatio-temporal stability analysis of a binary liquid film flowing down an inclined uniformly heated plate

    Science.gov (United States)

    Hu, Jun; Hadid, Hamda Ben; Henry, Daniel; Mojtabi, Abdelkader

    Temporal and spatio-temporal instabilities of binary liquid films flowing down an inclined uniformly heated plate with Soret effect are investigated by using the Chebyshev collocation method to solve the full system of linear stability equations. Seven dimensionless parameters, i.e. the Kapitza, Galileo, Prandtl, Lewis, Soret, Marangoni, and Biot numbers (Ka, G, Pr, L, ) are used to control the flow system. In the case of pure spanwise perturbations, thermocapillary S- and P-modes are obtained. It is found that the most dangerous modes are stationary for positive Soret numbers (0), and oscillatory for =0 remains so for >0 and even merges with the long-wave S-mode. In the case of streamwise perturbations, a long-wave surface mode (H-mode) is also obtained. From the neutral curves, it is found that larger Soret numbers make the film flow more unstable as do larger Marangoni numbers. The increase of these parameters leads to the merging of the long-wave H- and S-modes, making the situation long-wave unstable for any Galileo number. It also strongly influences the short-wave P-mode which becomes the most critical for large enough Galileo numbers. Furthermore, from the boundary curves between absolute and convective instabilities (AI/CI) calculated for both the long-wave instability (S- and H-modes) and the short-wave instability (P-mode), it is shown that for small Galileo numbers the AI/CI boundary curves are determined by the long-wave instability, while for large Galileo numbers they are determined by the short-wave instability.

  19. Numerical simulation of effect of catalyst wire-mesh pressure drop characteristics on flow distribution in catalytic parallel plate steam reformer

    DEFF Research Database (Denmark)

    Sigurdsson, Haftor Örn; Kær, Søren Knudsen

    2012-01-01

    Steam reforming of hydrocarbons using a catalytic plate-type-heat-exchanger (CPHE) reformer is an attractive method of producing hydrogen for a fuel cell-based micro combined-heat-and-power system. In this study the flow distribution in a CPHE reformer, which uses a coated wire-mesh catalyst...

  20. Flows around a moving flat plate simulated by the method of cellular automata. Seru outoman ho ni yoru ido heiban mawari no nagare

    Energy Technology Data Exchange (ETDEWEB)

    Tsutahara, M; Tomiyama, A; Kimura, T; Murata, H [Kobe University, Kobe (Japan). Faculty of Engineering

    1993-08-25

    In order to analyze the field of flow containing a moving boundary by the method of cellular automaton, the method of giving the boundary conditions in the case where a wall is moving at a constant velocity in the normal direction was examined. This method is used to simulate the movement of continuous fluid by statistically treating the movement of many discrete particles which repeat translation and collision. The collision law of particles at grid points is formulated so as to conserve mass(number of particles) and momentum for the purpose of satisfying the governing equation of flow. The object is the flow in the case where a flat plate moves in the normal direction inside the fluid enclosed by rectangular walls and the plate was assumed that it is first in a standing condition, then starts to move from left to right at a speed of V and stops in front of the right wall. Three boundary conditions, surrounding wall, plate in the standing condition and moving plate, were considered. Flow rates were calculated concerning the translation and collision and each divided mean-field-approximation region(space having a magnitude of capable of averaging operation of particles). Effectiveness of proposed boundary conditions was confirmed by a visualization experiment. 3 refs., 14 figs.

  1. Standardized performance tests of collectors of solar thermal energy-a flat-plate collector with a single-tube serpentine flow distribution

    Science.gov (United States)

    Johnson, S.

    1976-01-01

    This preliminary data report gives basic test results of a flat-plate solar collector whose performance was determined in the NASA-Lewis solar simulator. The collector was tested over ranges of inlet temperatures, fluxes and coolant flow rates. Collector efficienty is correlated in terms of inlet temperature and flux level.

  2. National Ignition Facility Target Chamber

    International Nuclear Information System (INIS)

    Wavrik, R W; Cox, J R; Fleming, P J

    2000-01-01

    On June 11, 1999 the Department of Energy dedicated the single largest piece of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) in Livermore, California. The ten (10) meter diameter aluminum target high vacuum chamber will serve as the working end of the largest laser in the world. The output of 192 laser beams will converge at the precise center of the chamber. The laser beams will enter the chamber in two by two arrays to illuminate 10 millimeter long gold cylinders called hohlraums enclosing 2 millimeter capsule containing deuterium, tritium and isotopes of hydrogen. The two isotopes will fuse, thereby creating temperatures and pressures resembling those found only inside stars and in detonated nuclear weapons, but on a minute scale. The NIF Project will serve as an essential facility to insure safety and reliability of our nation's nuclear arsenal as well as demonstrating inertial fusion's contribution to creating electrical power. The paper will discuss the requirements that had to be addressed during the design, fabrication and testing of the target chamber. A team from Sandia National Laboratories (SNL) and LLNL with input from industry performed the configuration and basic design of the target chamber. The method of fabrication and construction of the aluminum target chamber was devised by Pitt-Des Moines, Inc. (PDM). PDM also participated in the design of the chamber in areas such as the Target Chamber Realignment and Adjustment System, which would allow realignment of the sphere laser beams in the event of earth settlement or movement from a seismic event. During the fabrication of the target chamber the sphericity tolerances had to be addressed for the individual plates. Procedures were developed for forming, edge preparation and welding of individual plates. Construction plans were developed to allow the field construction of the target chamber to occur parallel to other NIF construction activities. This was

  3. Ionization chambers

    International Nuclear Information System (INIS)

    Boag, J.W.

    1987-01-01

    Although a variety of solid-state and chemical methods for measuring radiation dose have been developed in recent decades and calorimetry can now provide an absolute standard of reference, ionization dosimetry retains its position as the most widely used, most convenient, and, in most situations, most accurate method of measuring either exposure or absorbed dose. The ionization chamber itself is the central element in this system of dosimetry. In this chapter the principles governing the construction and operation of ionization chambers of various types are examined. Since the ionization chambers now in general use are nearly all of commercial manufacture, the emphasis is on operating characteristics and interpretation of measurements rather than on details of construction, although some knowledge of the latter is often required when applying necessary corrections to the measured quantities. Examples are given of the construction of typical chambers designed for particular purposes, and the methods of calibrating them are discussed

  4. Fast intraslab fluid-flow events linked to pulses of high pore fluid pressure at the subducted plate interface

    Science.gov (United States)

    Taetz, Stephan; John, Timm; Bröcker, Michael; Spandler, Carl; Stracke, Andreas

    2018-01-01

    A better understanding of the subduction zone fluid cycle and its chemical-mechanical feedback requires in-depth knowledge about how fluids flow within and out of descending slabs. Relicts of fluid-flow systems in exhumed rocks of fossil subduction zones allow for identification of the general relationships between dehydration reactions, fluid pathway formation, the dimensions and timescales of distinct fluid flow events; all of which are required for quantitative models for fluid-induced subduction zone processes. Two types of garnet-quartz-phengite veins can be distinguished in an eclogite-facies mélange block from the Pouébo Eclogite Mélange, New Caledonia. These veins record synmetamorphic internal fluid release by mineral breakdown reactions (type I veins), and infiltration of an external fluid (type II veins) with the associated formation of a reaction selvage. The dehydration and fluid migration documented by the type I veins likely occurred on a timescale of 105-106 years, based on average subduction rates and metamorphic conditions required for mineral dehydration and fluid flow. The timeframe of fluid-rock interaction between the external fluid and the wall-rock of the type II veins is quantified using a continuous bulk-rock Li-diffusion profile perpendicular to a vein and its metasomatic selvage. Differences in Li concentration between the internal and external fluid reservoirs resulted in a distinct diffusion profile (decreasing Li concentration and increasing δ7 Li) as the reaction front propagated into the host rock. Li-chronometric constraints indicate that the timescales of fluid-rock interaction associated with type II vein formation are on the order of 1 to 4 months (0.150-0.08+0.14 years). The short-lived, pulse-like character of this process is consistent with the notion that fluid flow caused by oceanic crust dehydration at the blueschist-to-eclogite transition contributes to or even dominates episodic pore fluid pressure increases at the

  5. Ionization of H2O molecules through second order collisions in an argon-filled flow ionization chamber

    International Nuclear Information System (INIS)

    Leonhardt, J.

    1976-01-01

    In an argon-filled ionization chamber with a constant radionuclide radiation source, the ionization of H 2 O through second order collisions with 3sub(p) 2 states of argon excited by field-accelerated electrons is considered within the range of discharge caused by external potentials under atmospheric pressure. It is found that the logarithm of the change of ionization current is proportional to power 3/2 of the electric field strength. Possible formation mechanisms are discussed. Most probable is the ionization of H 2 O through collision with Ar 2 argon dimers originating from excited metastable atoms as a result of triple collision. The production cross section for H 2 O + has been estimated to be sigmasub(H 2 O) approximately 5x10 -15 . (author)

  6. Heat and fluid flow properties of circular impinging jet with a low nozzle to plate spacing. Improvement by nothched nozzle; Nozzle heibankan kyori ga chiisai baai no enkei shototsu funryu no ryudo dennetsu tokusei. Kirikaki nozzle ni yoru kaizen kojo

    Energy Technology Data Exchange (ETDEWEB)

    Shakouchih, T. [Mie University, Mie (Japan). Faculty of Engineering; Matsumoto, A.; Watanabe, A.

    2000-10-25

    It is well known that as decreasing the nozzle to plate spacing considerably the heat transfer coefficient of circular impinging jet, which impinges to the plate normally, increases remarkably. At that time, the flow resistance of nozzle-plate system also increases rapidly. In this study, in order to reduce the flow resistance and to enhance the heat transfer coefficient of the circular impinging jet with a considerably low nozzle to plate spacing, a special nozzle with notches is proposed, and considerable improvement of the flow and heat transfer properties are shown. The mechanism of enhancement of the heat transfer properties is also discussed. (author)

  7. The Liquid Nitrogen System for Chamber A: A Change from Original Forced Flow Design to a Natural Flow (Thermo Siphon) System

    Science.gov (United States)

    Homan, Jonathan; Montz, Michael; Sidi-Yekhlef, Ahmed; Ganni, Venkatarao (Rao); Knudsen, Peter; Garcia, Sam; Linza, Robert; Meagher, Daniel; Lauterbauch, John

    2008-01-01

    NASA Johnson Space Center (JSC) in Houston is currently supplementing its 20K helium refrigeration system to meet the new requirements for testing the James Web Space Telescope in the environmental control Chamber-A (65 dia x 120 high) in Building 32. The new system is required to meet the various operating modes which include a high 20K heat load, a required temperature stability at the load, rapid (but controlled) cool down and warm up and bake out of the chamber. This paper will present the proposed modifications to the existing helium system(s) to incorporate the new requirements and the integration of the new helium refrigerator with the existing two 3.5KW 20K helium refrigerators. In addition, the floating pressure process control philosophy to achieve high efficiency over the operating range (40% to 100% of the refrigeration system capacity), and the required temperature stability of +/- 0.25 K at the load will be discussed. The refrigeration systems ability to naturally seek the operating conditions under various loads and thus minimizing operator involvement and the over all improvements to the system operability and the reliability will be explained.

  8. A liquid ionization chamber using tetramethylsilane

    International Nuclear Information System (INIS)

    Engler, J.; Keim, H.

    1983-12-01

    First results with a liquid ionization chamber using tetramethylsilane (TMS) are presented. A stack of iron plates was tested with cosmic ray muons and the charge output for minimum ionizing particles was measured. (orig.) [de

  9. Effects of Port Shape on Steady Flow Characteristics in an SI Engine with Semi-Wedge Combustion Chamber (2) - Velocity Distribution (2)

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Inkyoung; Ohm, Inyong [Seoul Nat’l Univ. of Science and Technology, Seoul (Korea, Republic of)

    2017-02-15

    This study is the second investigation on the steady flow characteristics of an SI engine with a semi-edge combustion chamber as a function of the port shape with varying evaluation positions. For this purpose, the planar velocity profiles were measured from 1.75B, 1.75 times of bore position apart from the bottom of head, to 6.00B positions using particle – image velocimetry. The flow patterns were examined with both a straight and a helical port. The velocity profiles, streamlines, and centers of swirl were almost the same at the same valve lift regardless of the measuring position, which is quite different from the case of the pent-roof combustion chamber. All the eccentricity values of the straight port were out of distortion criterion 0.15 through the lifts and the position. However, the values of the helical port exceeded the distortion criterion by up to 4 mm lift, but decreased rapidly above the 3.00B position and the 5 mm lift. There always existed a relative offset effect in the evaluation of the swirl coefficient using the PIV method due to the difference of the ideal impulse swirl meter velocity profile assumption, except for the cylinder-center-base estimation that was below 4 mm of the straight port. Finally, it was concluded that taking the center as an evaluation basis and the assumption about the axial velocity profile did not have any qualitative effect on swirl evaluation, but affected the value owing to the detailed profile.

  10. Cloud Chamber

    DEFF Research Database (Denmark)

    Gfader, Verina

    Cloud Chamber takes its roots in a performance project, titled The Guests 做东, devised by Verina Gfader for the 11th Shanghai Biennale, ‘Why Not Ask Again: Arguments, Counter-arguments, and Stories’. Departing from the inclusion of the biennale audience to write a future folk tale, Cloud Chamber......: fiction and translation and translation through time; post literacy; world picturing-world typing; and cartographic entanglements and expressions of subjectivity; through the lens a social imaginary of worlding or cosmological quest. Art at its core? Contributions by Nikos Papastergiadis, Rebecca Carson...

  11. wire chamber

    CERN Multimedia

    1985-01-01

    Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  12. Wire chamber

    CERN Multimedia

    Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  13. wire chamber

    CERN Multimedia

    Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  14. wire chamber

    CERN Multimedia

    Was used in ISR (Intersecting Storage Ring) split field magnet experiment. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  15. The performance of a hybrid spark chamber beta-ray camera

    International Nuclear Information System (INIS)

    Aoyama, Takahiko; Watanabe, Tamaki

    1978-01-01

    This paper describes the performance of a hybrid spark chamber for measuring β-ray emitting radionuclide distribution on a plane source, which was developed to improve the instability of usual self-triggering spark chambers. The chamber consists of a parallel plate spark chamber gap and a parallel plate proportional chamber gap composed of mesh electrodes in the same gas space, and is operated by flowing gas, a mixture of argon and ethanol saturated vapor at 0 0 C, continuously through it. Instability is due to the occurrence of spurious sparks not caused by incident particles and it became conspicuous in the small intensity of incident particles. The hybrid spark chamber enabled us to obtain good counting plateau, that is, good stability for especially small intensity of β-rays and even for the background by setting up gas multiplication in the proportional chamber gap moderately high. Good spatial resolution less than 1 mm was obtained for 3 H and 14 C by keeping the distance between the chamber cathode and the source less than 1 mm. In order to obtain good spatial resolution, it is desirable to keep the overvoltage as small as possible while small overvoltage results in the deterioration of the uniformity of sensitivity. It was found by theoretical estimation and experiment that for a given large overvoltage the spatial resolution was improved by increasing the gas multiplication in the proportional chamber gap. The hybrid spark chamber has a relatively long dead time. When there being a number of active spots having different activities in a detection area, the sparking efficiency of a weak active spot also decreases by large counting loss due to the total strong activity. (auth.)

  16. Finite element modeling of penetration of rigid cylindrical bar impacting on a clamped circular plate, employing a strain rate dependent flow rate and a Gruneisen equation of state

    International Nuclear Information System (INIS)

    Tariq, M.; Khan, I.A.

    2003-01-01

    A time dependent Finite Element simulation of penetration of a rigid cylindrical bar impacting on a copper plate is conducted, to demonstrate how material behavior appears to change when Johnson-Cook plasticity rule is employed along with a Gruneisen, equation of state with cubic shock velocity-particle relationship, and defining pressure both for compressed and expanded materials, as compared to the behavior when only isotropic strain-hardening model is employed. The bar impacts the plate with a velocity of 1000 m/s, and penetrates the plate, a portion of it coming out of the other side. Results are obtained and compared taking both an isotropic strain-hardening model, and a model incorporating Johnson-Cook flow rule along with Gruneisen equation of state. (author)

  17. HEAT AND MASS TRANSFER EFFECTS ON FLOW PAST PARABOLIC STARTING MOTION OF ISOTHERMAL VERTICAL PLATE IN THE PRESENCE OF FIRST ORDER CHEMICAL REACTION

    Directory of Open Access Journals (Sweden)

    R. Muthucumaraswamy

    2013-06-01

    Full Text Available An exact solution of unsteady flow past a parabolic starting motion of the infinite isothermal vertical plate with uniform mass diffusion, in the presence of a homogeneous chemical reaction of the first order, has been studied. The plate temperature and the concentration level near the plate are raised uniformly. The dimensionless governing equations are solved using the Laplace transform technique. The effect of velocity profiles are studied for different physical parameters, such as chemical reaction parameter, thermal Grashof number, mass Grashof number, Schmidt number, and time. It is observed that velocity increases with increasing values of thermal Grashof number or mass Grashof number. The trend is reversed with respect to the chemical reaction parameter.

  18. Picture chamber for radiographic system

    International Nuclear Information System (INIS)

    1977-01-01

    The picture chamber for a radiographic system is characterised by a base, a first electrode carried in the base, an X-ray irradiation window provided with an outer plate and an inner plate and a conducting surface which serves as a second electrode, which has a plate gripping it at each adjacent edge and which has at the sides a space which is occupied by a filling material, maintained at a steady pressure, by means of the mounting against the base and wherein the inner plate lies against the first electrode and which is provided with a split, and with means for the separation of the split in the area of the inner plate so that a fluid may be retained in the split. (G.C.)

  19. Inverse models of plate coupling and mantle rheology: Towards a direct link between large-scale mantle flow and mega thrust earthquakes

    Science.gov (United States)

    Gurnis, M.; Ratnaswamy, V.; Stadler, G.; Rudi, J.; Liu, X.; Ghattas, O.

    2017-12-01

    We are developing high-resolution inverse models for plate motions and mantle flow to recover the degree of mechanical coupling between plates and the non-linear and plastic parameters governing viscous flow within the lithosphere and mantle. We have developed adjoint versions of the Stokes equations with fully non-linear viscosity with a cost function that measures the fit with plate motions and with regional constrains on effective upper mantle viscosity (from post-glacial rebound and post seismic relaxation). In our earlier work, we demonstrate that when the temperature field is known, the strength of plate boundaries, the yield stress and strain rate exponent in the upper mantle are recoverable. As the plate boundary coupling drops below a threshold, the uncertainty of the inferred parameters increases due to insensitivity of plate motion to plate coupling. Comparing the trade-offs between inferred rheological parameters found from a Gaussian approximation of the parameter distribution and from MCMC sampling, we found that the Gaussian approximation—which is significantly cheaper to compute—is often a good approximation. We have extended our earlier method such that we can recover normal and shear stresses within the zones determining the interface between subducting and over-riding plates determined through seismic constraints (using the Slab1.0 model). We find that those subduction zones with low seismic coupling correspond with low inferred values of mechanical coupling. By fitting plate motion data in the optimization scheme, we find that Tonga and the Marianas have the lowest values of mechanical coupling while Chile and Sumatra the highest, among the subduction zones we have studies. Moreover, because of the nature of the high-resolution adjoint models, the subduction zones with the lowest coupling have back-arc extension. Globally we find that the non-linear stress-strain exponent, n, is about 3.0 +/- 0.25 (in the upper mantle and lithosphere) and a

  20. The Pd distribution and Cu flow pattern of the Pd-plated Cu wire bond and their effect on the nanoindentation

    International Nuclear Information System (INIS)

    Lin, Yu-Wei; Wang, Ren-You; Ke, Wun-Bin; Wang, I-Sheng; Chiu, Ying-Ta; Lu, Kuo-Chang; Lin, Kwang-Lung; Lai, Yi-Shao

    2012-01-01

    Highlights: ► Pd distribution in Pd-plated Cu wires reveals the whirlpool flow pattern of Cu. ► The mechanisms of the Cu flow behavior and Pd distribution are proposed. ► At Pd-rich phases, small voids formed and followed the direction of Cu flow. ► Nanoindentation studies show the Cu ball bond is harder in regions with Pd. - Abstract: The Pd plating on the 20 μm Cu wire dissolves in the free air ball (FAB) and the Cu ball bond during the wire bonding process without forming intermetallic compounds. The limiting supply of Pd and the short bonding process, 15 ms of thermosonic bonding, result in uneven distribution of Pd in the as produced Cu ball bond. Also, the Pd-rich phase may accompany small voids formed within the FAB and the wire bond, and following the direction of semi-solid Cu flow. The Pd distribution, as evidenced by the focused ion beam (FIB) and wavelength dispersive X-ray spectroscopy (WDS) mapping, reveals the whirlpool flow pattern of Cu within the FAB and the ball bond. Pd distributes within the copper ball through convective transport by the copper flow. Additionally, hardness measurements by nanoindentation testing show that the Cu ball bond is harder in the regions where Pd exists.

  1. Application of particle image velocimetry measurement techniques to study turbulence characteristics of oscillatory flows around parallel-plate structures in thermoacoustic devices

    International Nuclear Information System (INIS)

    Mao, Xiaoan; Jaworski, Artur J

    2010-01-01

    This paper describes the development of the experimental setup and measurement methodologies to study the physics of oscillatory flows in the vicinity of parallel-plate stacks by using the particle image velocimetry (PIV) techniques. Parallel-plate configurations often appear as internal structures in thermoacoustic devices and are responsible for the hydrodynamic energy transfer processes. The flow around selected stack configurations is induced by a standing acoustic wave, whose amplitude can be varied. Depending on the direction of the flow within the acoustic cycle, relative to the stack, it can be treated as an entrance flow or a wake flow. The insight into the flow behaviour, its kinematics, dynamics and scales of turbulence, is obtained using the classical Reynolds decomposition to separate the instantaneous velocity fields into ensemble-averaged mean velocity fields and fluctuations in a set of predetermined phases within an oscillation cycle. The mean velocity field and the fluctuation intensity distributions are investigated over the acoustic oscillation cycle. The velocity fluctuation is further divided into large- and small-scale fluctuations by using fast Fourier transform (FFT) spatial filtering techniques

  2. One-dimensional curved wire chamber for powder x-ray crystallography

    International Nuclear Information System (INIS)

    Ortendahl, D.; Perez-Mendez, V.; Stoker, J.; Beyermann, W.

    1978-01-01

    A xenon filled single anode wire chamber with delay line readout has been constructed for use in powder x-ray crystallography using 8 to 20 keV x-rays. The entire chamber including the anode wire and the delay line which forms part of the cathode plane is a section of a circular arc whose center is the powder specimen. The anode wire--38 μm gold-plated tungsten--is suspended in a circular arc by the interaction of a current flowing through it and magnetic field provided by two permanent magnets, above and below the wire, extending along the active length of the chamber. When filled with xenon to 3 atmospheres the chamber has uniform sensitivity in excess of 80% at 8 keV and a spatial resolution better than 0.3 mm

  3. Local study of flow and low Reynolds thermal-hydraulic performance of a corrugated plane duct: application to plate heat exchangers

    International Nuclear Information System (INIS)

    Hugonnot, Patrick

    1989-01-01

    This research thesis addresses the local study of a flow in a corrugated plane duct by using experimental and numerical approaches on the one hand, and the experimental determination of thermal-hydraulic performance at low Reynolds number of different plate heat exchanger ducts on the other hand. Experimental visualisations of the local flow allowed regime transitions in 2D and 3D geometries to be determined. As far as the 2D duct is concerned, a wave profile optimisation is proposed, and the numerical study performed by using the TRIO software is in good agreement with experimental results. The optimised duct configuration can thus be envisaged for an industrial development. The determination of the friction coefficient and of the global heat exchange coefficient of different corrugated ducts allows plate exchangers to be sized on a wide range of Reynolds numbers. The respective influences of natural convection and of fluid thermal dependency on heat exchange have been studied [fr

  4. A synthetic layout optimization of discrete heat sources flush mounted on a laminar flow cooled flat plate based on the constructal law

    International Nuclear Information System (INIS)

    Shi, Zhongyuan; Dong, Tao

    2015-01-01

    Highlights: • A constructal thermohydraulic optimization was carried out. • The effect of manufacturing limit on the Pareto solution set was discussed. • The suitable constraints may differ from those on a quasi-continuous basis. - Abstract: A synthetic optimization is presented for the Pareto layouts of discrete heat sources (with uniform heat flux) flush mounted on a flat plate over which laminar flow serves for cooling purpose. The peak temperatures and the flow drag loss are minimizing simultaneously provided that the total heat dissipation rate and the plate length are held constant. The impact of the manufacturing limit, i.e. the minimum length of the heated or the adiabatic patch, on the optimum layout is discussed. The results in general comply with analytical deduction based on the constructal theory. However in a finite length scenario, geometric constraints on the adiabatic spacing differ from that fits the situation in which maximum heat transfer performance alone is to be achieved.

  5. A similar solution for an unsteady free convection flow past an impulsively started vertical plate with mass transfer and suction or injection

    International Nuclear Information System (INIS)

    Sattar, M.A.

    1990-12-01

    A similar solution for the flow past a vertical plate started impulsively in its own plane in a viscous incompressible fluid is presented on taking into account the effects of variable suction and/or injection and mass transfer. To solve the momentum, energy and concentration equations, a time dependent length scale is introduced, which leads to the driving parameters γ(=G r /R σ 2 ) and γ*(=G r */R σ 2 ), where G r and G r * are respectively the Grashof and modified Grashof numbers while R σ is the Reynolds number. The resulting locally similar momentum equation is then solved by the method of superposition. The effects of the parameters and that of suction/injection on the flow and on the wall shear-stress of the plate are shown graphically for different values of Schmidt number and transpiration parameter. (author). 24 refs, 11 figs

  6. A membrane-free, continuously feeding, single chamber up-flow biocatalyzed electrolysis reactor for nitrobenzene reduction

    International Nuclear Information System (INIS)

    Wang, Ai-Jie; Cui, Dan; Cheng, Hao-Yi; Guo, Yu-Qi; Kong, Fan-Ying; Ren, Nan-Qi; Wu, Wei-Min

    2012-01-01

    Highlights: ► A novel membrane-free up-flow biocatalyzed electrolysis reactor (UBER) was developed. ► Nitrobenzene as the mode of nitroaromatics was efficiently converted to aniline. ► The impact of phosphate buffer and acetate concentrations and power supplied were investigated. ► The prospects of UBER for the recalcitrant compound removal were discussed. - Abstract: A new bioelectrochemical system (BES), a membrane-free, continuous feeding up-flow biocatalyzed electrolysis reactor (UBER) was developed to reduce oxidative toxic chemicals to less- or non-toxic reduced form in cathode zone with oxidation of electron donor in anode zone. Influent was fed from the bottom of UBER and passed through cathode zone and then anode zone. External power source (0.5 V) was provided between anode and cathode to enhance electrochemical reactions. Granular graphite and carbon brush were used as cathode and anode, respectively. This system was tested for the reduction of nitrobenzene (NB) using acetate as electron donor and carbon source. The influent contained NB (50–200 mg L −1 ) and acetate (1000 mg L −1 ). NB was removed by up to 98% mainly in cathode zone. The anode potential maintained under −480 mV. The maximum NB removal rate was up to 3.5 mol m −3 TV d −1 (TV = total empty volume) and the maximum aniline (AN) formation rate was 3.06 mol m −3 TV d −1 . Additional energy required was less than 0.075 kWh mol −1 NB. The molar ratio of NB removed vs acetate consumed varied from 4.3 ± 0.4 to 2.3 ± 0.1 mol mol −1 . Higher influent phosphate or acetate concentration helped NB removal rate. NB could be efficiently reduced to AN as the power supplied of 0.3 V.

  7. Liquid Wall Chambers

    Energy Technology Data Exchange (ETDEWEB)

    Meier, W R

    2011-02-24

    The key feature of liquid wall chambers is the use of a renewable liquid layer to protect chamber structures from target emissions. Two primary options have been proposed and studied: wetted wall chambers and thick liquid wall (TLW) chambers. With wetted wall designs, a thin layer of liquid shields the structural first wall from short ranged target emissions (x-rays, ions and debris) but not neutrons. Various schemes have been proposed to establish and renew the liquid layer between shots including flow-guiding porous fabrics (e.g., Osiris, HIBALL), porous rigid structures (Prometheus) and thin film flows (KOYO). The thin liquid layer can be the tritium breeding material (e.g., flibe, PbLi, or Li) or another liquid metal such as Pb. TLWs use liquid jets injected by stationary or oscillating nozzles to form a neutronically thick layer (typically with an effective thickness of {approx}50 cm) of liquid between the target and first structural wall. In addition to absorbing short ranged emissions, the thick liquid layer degrades the neutron flux and energy reaching the first wall, typically by {approx}10 x x, so that steel walls can survive for the life of the plant ({approx}30-60 yrs). The thick liquid serves as the primary coolant and tritium breeding material (most recent designs use flibe, but the earliest concepts used Li). In essence, the TLW places the fusion blanket inside the first wall instead of behind the first wall.

  8. Analysis Of Convective Plane Stagnation Point Chemically Reactive Mhd Flow Past A Vertical Porous Plate With A Convective Boundary Condition In The Presence Of A Uniform Magnetic Field.

    OpenAIRE

    Adeniyan, A.,

    2013-01-01

    The numerical investigation of a stagnation point boundary layer flow , mass and heat transfer of a steady two dimensional , incompressible , viscous electrically conducting, chemically reacting laminar fluid over a vertical convectively heated , electrically neutral flat plate exposed to a transverse uniform magnetic field has been carried out to examine the influence of the simultaneous presence of the effects of a convective boundary condition, chemical reaction, heat transfer and suctio...

  9. Critical heat flux analysis on change of plate temperature and cooling water flow rate for rectangular narrow gap with bilateral-heated cases

    International Nuclear Information System (INIS)

    M Hadi Kusuma; Mulya Juarsa; Anhar Riza Antariksawan

    2013-01-01

    Boiling heat transfer phenomena on rectangular narrow gap was related to the safety of nuclear reactors. Research done in order to study the safety of nuclear reactors in particular relating to boiling heat transfer and useful on the improvement of next-generation reactor designs. The research focused on calculation of the heat flux during the cooling process in rectangular narrow gap size 1.0 mm. with initial temperatures 200°C. 400°C, and 600°C, also the flow rates of cooling water 0,1 liters/second. 0,2 liters/second. and 0,3 liters/second. Experiments carried out by injecting water at a certain flow rate with the water temperature 85°C. Transient temperature measurement data recorded by the data acquisition system. Transient temperature measurement data is used to calculate the flux of heat gain is then used to obtain the heat transfer coefficient. This research aimed to obtain the correlation between critical heat flux and heat transfer coefficient to changes in temperatures and water flow rates for bilaterally-heated cases on rectangular narrow gap. The results obtained for a constant cooling water flow rate, critical heat flux will increase when hot plate temperature also increased. While on a constant hot plate temperature, coefficient heat transfer will increase when cooling water flow rate also increased. Thus it can be said that the cooling water flow rate and temperature of the hot plate has a significant effect on the critical heat flux and heat transfer coefficient resulted in quenching process of vertical rectangular narrow gap with double-heated cases. (author)

  10. MHD Heat and Mass Transfer of Chemical Reaction Fluid Flow over a Moving Vertical Plate in Presence of Heat Source with Convective Surface Boundary Condition

    Directory of Open Access Journals (Sweden)

    B. R. Rout

    2013-01-01

    Full Text Available This paper aims to investigate the influence of chemical reaction and the combined effects of internal heat generation and a convective boundary condition on the laminar boundary layer MHD heat and mass transfer flow over a moving vertical flat plate. The lower surface of the plate is in contact with a hot fluid while the stream of cold fluid flows over the upper surface with heat source and chemical reaction. The basic equations governing the flow, heat transfer, and concentration are reduced to a set of ordinary differential equations by using appropriate transformation for variables and solved numerically by Runge-Kutta fourth-order integration scheme in association with shooting method. The effects of physical parameters on the velocity, temperature, and concentration profiles are illustrated graphically. A table recording the values of skin friction, heat transfer, and mass transfer at the plate is also presented. The discussion focuses on the physical interpretation of the results as well as their comparison with previous studies which shows good agreement as a special case of the problem.

  11. Study of uranium plating measurement

    International Nuclear Information System (INIS)

    Lin Jufang; Wen Zhongwei; Wang Mei; Wang Dalun; Liu Rong; Jiang Li; Lu Xinxin

    2007-06-01

    In neutron physics experiments, the measurement for plate-thickness of uranium can directly affect uncertainties of experiment results. To measure the plate-thickness of transform target (enriched uranium plating and depleted uranium plating), the back to back ionization chamber, small solid angle device and Au-Si surface barrier semi-conductor, were used in the experiment study. Also, the uncertainties in the experiment were analyzed. Because the inhomo-geneous of uranium lay of plate can quantitively affect the result, the homogeneity of uranium lay is checked, the experiment result reflects the homogeneity of uranium lay is good. (authors)

  12. Chemical reaction effect on an unsteady MHD free convection flow past a vertical porous plate in the presence of suction or injection

    Directory of Open Access Journals (Sweden)

    Shivaiah S.

    2012-01-01

    Full Text Available The objective of this paper is to analyze the effect of chemical reaction on unsteady magneto hydrodynamic free convective fluid flow past a vertical porous plate in the presence of suction or injection. The governing equations of the flow field are solved numerically by a finite element method. The effects of the various parameters on the velocity, temperature and concentration profiles are presented graphically and values of skin-friction coefficient, Nusselt number and Sherwood number for various values of physical parameters are presented through tables.

  13. Using an equation based on flow stress to estimate structural integrity of annealed Type 304 stainless steel plate and pipes containing surface defects

    International Nuclear Information System (INIS)

    Reuter, W.G.; Place, T.A.

    1981-01-01

    An accurate assessment of the influence of defects on structural component integrity is needed. Generally accepted analytical techniques are not available for the very ductile materials used in many nuclear reactor components. Some results are presented from a test programme to obtain data by which to evaluate proposed models. Plate and pipe specimens containing surface flaws were fabricated from annealed Type 304 stainless steel and tested at room temperature. An evaluation of an empirical equation based on flow stress is presented. In essentially all instances the flow stress is not a constant but varies as a function of the size of the surface flaw. (author)

  14. Some Exact Solutions of Boundary Layer Flows along a Vertical Plate with Buoyancy Forces Combined with Lorentz Forces under Uniform Suction

    Directory of Open Access Journals (Sweden)

    Asterios Pantokratoras

    2008-01-01

    Full Text Available Exact analytical solutions of boundary layer flows along a vertical porous plate with uniform suction are derived and presented in this paper. The solutions concern the Blasius, Sakiadis, and Blasius-Sakiadis flows with buoyancy forces combined with either MHD Lorentz or EMHD Lorentz forces. In addition, some exact solutions are presented specifically for water in the temperature range of 0∘C≤≤8∘C, where water density is nearly parabolic. Except for their use as benchmarking means for testing the numerical solution of the Navier-Stokes equations, the presented exact solutions with EMHD forces have use in flow separation control in aeronautics and hydronautics, whereas the MHD results have applications in process metallurgy and fusion technology. These analytical solutions are valid for flows with strong suction.

  15. Heat transfer in flow past a continuously moving semi-infinite flat plate in transverse magnetic field with heat flux

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, T.V.R.

    Thermal boundary layer on a continuously moving semi-infinite flat plate in the presence of transverse magnetic field with heat flux has been examined. Similarity solutions have been derived and the resulting equations are integrated numerically...

  16. A Study of Chemically Reactive Species and Thermal Radiation Effects on an Unsteady MHD Free Convection Flow Through a Porous Medium Past a Flat Plate with Ramped Wall Temperature

    Directory of Open Access Journals (Sweden)

    Pandit K. K.

    2017-12-01

    Full Text Available An investigation of the effects of a chemical reaction and thermal radiation on unsteady MHD free convection heat and mass transfer flow of an electrically conducting, viscous, incompressible fluid past a vertical infinite flat plate embedded in a porous medium is carried out. The flow is induced by a general time-dependent movement of the vertical plate, and the cases of ramped temperature and isothermal plates are studied. An exact solution of the governing equations is obtained in closed form by the Laplace Transform technique. Some applications of practical interest for different types of plate motions are discussed. The numerical values of fluid velocity, temperature and species concentration are displayed graphically whereas the numerical values of skin friction, Nusselt number and Sherwood number are presented in a tabular form for various values of pertinent flow parameters for both ramped temperature and isothermal plates.

  17. A Study of Chemically Reactive Species and Thermal Radiation Effects on an Unsteady MHD Free Convection Flow Through a Porous Medium Past a Flat Plate with Ramped Wall Temperature

    Science.gov (United States)

    Pandit, K. K.; Sarma, D.; Singh, S. I.

    2017-12-01

    An investigation of the effects of a chemical reaction and thermal radiation on unsteady MHD free convection heat and mass transfer flow of an electrically conducting, viscous, incompressible fluid past a vertical infinite flat plate embedded in a porous medium is carried out. The flow is induced by a general time-dependent movement of the vertical plate, and the cases of ramped temperature and isothermal plates are studied. An exact solution of the governing equations is obtained in closed form by the Laplace Transform technique. Some applications of practical interest for different types of plate motions are discussed. The numerical values of fluid velocity, temperature and species concentration are displayed graphically whereas the numerical values of skin friction, Nusselt number and Sherwood number are presented in a tabular form for various values of pertinent flow parameters for both ramped temperature and isothermal plates.

  18. Hydrodynamics of a flexible plate between pitching rigid plates

    Science.gov (United States)

    Kim, Junyoung; Kim, Daegyoum

    2017-11-01

    The dynamics of a flexible plate have been studied as a model problem in swimming and flying of animals and fluid-structure interaction of plants and flags. Motivated by fish schooling and an array of sea grasses, we investigate the dynamics of a flexible plate closely placed between two pitching rigid plates. In most studies on passive deformation of the flexible plate, the plate is immersed in a uniform flow or a wavy flow. However, in this study, the flexible plate experiences periodic deformation by the oscillatory flow generated by the prescribed pitching motion of the rigid plates. In our model, the pitching axes of the rigid plates and the clamping position of the flexible plate are aligned on the same line. The flexible plate shows various responses depending on length and pitching frequency of rigid plates, thickness of a flexible plate, and free-stream velocity. To find the effect of each variable on the response of the flexible plate, amplitude of a trailing edge and modal contribution of a flapping motion are compared, and flow structure around the flexible plate is examined.

  19. Magmatic structures in the Krkonoše Jizera Plutonic Complex, Bohemian Massif: evidence for localized multiphase flow and small-scale thermal mechanical instabilities in a granitic magma chamber

    Science.gov (United States)

    Žák, Jiří; Klomínský, Josef

    2007-08-01

    The present paper examines magmatic structures in the Jizera and Liberec granites of the Krkonoše-Jizera Plutonic Complex, Bohemian Massif. The magmatic structures are here interpreted to preserve direct field evidence for highly localized magma flow and other processes in crystal-rich mushes, and to capture the evolution of physical processes in an ancient granitic magma chamber. We propose that after chamber-wide mixing and hybridization, as suggested by recent petrological studies, laminar magma flow became highly localized to weaker channel-like domains within the higher-strength crystal framework. Mafic schlieren formed at flow rims, and their formation presumably involved gravitational settling and velocity gradient flow sorting coupled with interstitial melt escape. Local thermal or compositional convection may have resulted in the formation of vertical schlieren tubes and ladder dikes whereas subhorizontal tubes or channels formed during flow driven by lateral gradients in magma pressure. After the cessation or deceleration of channel flow, gravity-driven processes (settling of crystals and enclaves, gravitational differentiation, development of downward dripping instabilities), accompanied by compaction, filter pressing and melt segregation, dominated in the crystal mush within the flow channels. Subsequently, magmatic folds developed in schlieren layers and the magma chamber recorded complex, late magmatic strains at high magma crystallinities. Late-stage magma pulsing into localized submagmatic cracks represents the latest events of magmatic history of the chamber prior to its final crystallization. We emphasize that the most favorable environments for the formation and preservation of magmatic structures, such as those hosted in the Jizera and Liberec granites, are slowly cooling crystal-rich mushes. Therefore, where preserved in plutons, these structures may lend strong support for a "mush model" of magmatic systems.

  20. Comparative evaluation of direct thrombin and factor Xa inhibitors with antiplatelet agents under flow and static conditions: an in vitro flow chamber model.

    Directory of Open Access Journals (Sweden)

    Kazuya Hosokawa

    Full Text Available Dabigatran and rivaroxaban are novel oral anticoagulants that specifically inhibit thrombin and factor Xa, respectively. The aim of this study is to elucidate antithrombotic properties of these anticoagulant agents under arterial and venous shear conditions. Whole blood samples treated with dabigatran or rivaroxaban at 250, 500, and 1000 nM, with/without aspirin and AR-C66096, a P2Y12 antagonist, were perfused over a microchip coated with collagen and tissue thromboplastin at shear rates of 240 and 600 s(-1. Fibrin-rich platelet thrombus formation was quantified by monitoring flow pressure changes. Dabigatran at higher concentrations (500 and 1000 nM potently inhibited thrombus formation at both shear rates, whereas 1000 nM of rivaroxaban delayed, but did not completely inhibit, thrombus formation. Dual antiplatelet agents weakly suppressed thrombus formation at both shear rates, but intensified the anticoagulant effects of dabigatran and rivaroxaban. The anticoagulant effects of dabigatran and rivaroxaban were also evaluated under static conditions using thrombin generation (TG assay. In platelet-poor plasma, dabigatran at 250 and 500 nM efficiently prolonged the lag time (LT and moderately reduce peak height (PH of TG, whereas rivaroxaban at 250 nM efficiently prolonged LT and reduced PH of TG. In platelet-rich plasma, however, both anticoagulants efficiently delayed LT and reduced PH of TG. Our results suggest that dabigatran and rivaroxaban may exert distinct antithrombotic effects under flow conditions, particularly in combination with dual antiplatelet therapy.