Oscillating acoustic streaming jet

International Nuclear Information System (INIS)

Moudjed, Brahim; Botton, Valery; Henry, Daniel; Millet, Severine; Ben Hadid, Hamda; Garandet, Jean-Paul

2014-01-01

The present paper provides the first experimental investigation of an oscillating acoustic streaming jet. The observations are performed in the far field of a 2 MHz circular plane ultrasound transducer introduced in a rectangular cavity filled with water. Measurements are made by Particle Image Velocimetry (PIV) in horizontal and vertical planes near the end of the cavity. Oscillations of the jet appear in this zone, for a sufficiently high Reynolds number, as an intermittent phenomenon on an otherwise straight jet fluctuating in intensity. The observed perturbation pattern is similar to that of former theoretical studies. This intermittently oscillatory behavior is the first step to the transition to turbulence. (authors)

Stability and contraction of a rectangular liquid metal jet in a vacuum environment

International Nuclear Information System (INIS)

Konkachbaev, A.I.; Morley, N.B.; Gulec, K.; Sketchley, T.

2000-01-01

Hydrodynamic similarity criteria and experimental data are reported here from experiments underway at UCLA that simulate the slab jets of the HYLIFE-II inertial fusion reactor. The current experimental setup produces a 2x20 mm slab jet, and reaches a maximum Reynolds number 5x10 4 , corresponding to a jet velocity of 12 m/s. A high-speed camera is used to obtain and analyze data. Two major phenomena are observed, the inversion (axis-switching) of the slab jet owing to surface tension and corner vortices; and surface waves due to turbulent velocity profile relaxation. The main purpose of this series of experiments is the study of the rapid inversion (almost 50% of the jet over the length of interest) seen in previous experiments. It is shown here that this was due to secondary flows caused by features of orifice nozzle design. Current experiments show an inversion length considerably in excess of analytic correlations based on 2-D inviscid theory. For parameters approaching HYLIFE-II jets, inversion length is shown to be more than several hundred non-dimensional lengths

Experimental investigation on carbon nano tubes coated brass rectangular extended surfaces

International Nuclear Information System (INIS)

Senthilkumar, Rajendran; Prabhu, Sethuramalingam; Cheralathan, Marimuthu

2013-01-01

Finned surface has been extensively used for free convection cooling of internal combustion engines and several electronic kits etc. Here rectangular brass fin was preferred for analysis. Thermocouples were attached all over the surface of the fin in equal distances. The measurement of surface temperature and calculated convective heat transfer rate were reported for several heat input values. The overall system performance can be improved by enhancing heat transfer rate of extended surfaces. Based on the above requirement, brass surface was coated by carbon nano tubes. The temperature and heat transfer characteristics were investigated using Taguchi method for experimental design. Finally the performances of coated and non-coated rectangular brass fins were compared. The average percentage of increase in heat transfer rate was proved around 12% for carbon nanocoated rectangular brass fins. - Graphical abstract: The designed Natural and Forced convection Heat Transfer Test Rig measures the enhanced rate of heat transfer for nano coated rectangular fins than in non-coated fins. Highlights: ► Rectangular brass fins were preferred for convective heat transfer process. ► The rectangular brass fins are coated with multi wall carbon nano tubes in EBPVD process with nanometer thickness. ► Temperature and heat transfer rate were investigated for nanocoated and non-coated fins by using Taguchi method. ► Multi wall carbon nanotubes act as a pin fin to enhance surface area for effective convective heat transfer rate.

Experimental thermo-aerodynamic characterisation of a jet in crossflow, impacting or not, in channel turbulence

International Nuclear Information System (INIS)

Fougairolle, P.

2009-07-01

This work consists in the experimental study of a jet in crossflow in a closed wind tunnel. Depending on the value of the velocity ratio (r U j /U∞), this confined rectangular jet can interact or impact with the opposite wall from the one it issues. The jet is slightly heated (∼10 C) in order to stay in the passive scalar case. An improvement of the experimental facility has been done to obtain thermal boundary conditions compatible with the measurements of slight differences of temperature, imposed by the passive scalar. Concerning the metrology, hot and cold wire anemometry and thermometry are used, and all the anemometric devices are developed and built in the lab. Probes made with Wollaston wire (Pt-Rh) of 0.35μm diameter are coupled with an anemometer and a thermometer optimized to maximize the signal to noise ratio. The results are obtained both thanks to visualizations by fast camera shots for several velocity ratios (r between 3 and 12), and thanks to local hot and cold wire measurements, in the particular case of two velocity ratios (r = 3.3 and 9.4). Mixing properties of the scalar are studied by the plot of statistical values of velocity and temperature in different plans, perpendicularly to the three axis. The analysis of spectral densities of the signals on several typical locations emphasizes some features of the dynamic behaviour of the jet. (author)

Experimental study of falling film evaporation in large scale rectangular channel

International Nuclear Information System (INIS)

Huang, X.G.; Yang, Y.H.; Hu, P.

2015-01-01

Highlights: • This paper studies the falling film evaporation in large scale rectangular channel experimentally. • The effects of air flow rate, film temperature and film flow rate on falling film evaporation are analyzed. • Increasing the air flow rate is considered as an efficient method to enhance the evaporation rate. • A correlation including the wave effect for falling film evaporation is derived based on heat and mass transfer analogy. - Abstract: The falling film evaporation in a large scale rectangular channel is experimentally studied in this paper for the design and improvement of passive containment cooling system. The evaporation mass transfer coefficient h D is obtained by the evaporation rate and vapor partial pressure difference of film surface and air bulk. The experimental results indicate that increasing of air flow rate appears to enhance h D , while the film temperature and film flow rate have little effect on h D . Since the wave effect on evaporation is noticed in experiment, the evaporation mass transfer correlation including the wave effect is developed on the basis of heat and mass transfer analogy and experimental data

Experimental investigation on flow instability of forced circulation in a vertical mini-rectangular channel

International Nuclear Information System (INIS)

Yu Zhiting; Tan Sichao; Yuan Hongsheng; Zhuang Nailiang; Chen Hanying

2015-01-01

An experimental study was conducted to investigate the flow instability in a vertical mini-rectangular channel with distilled water as the working fluid. The rotational speed of the primary pump is gradually reduced to lower the inlet flow rate until the flow becomes unstable, while maintaining all other thermal parameters unchanged. Three types of instability, characterized by large amplitude oscillation, small amplitude oscillation and flow excursion, were identified from the experimental data. A stability map for the vertical mini-rectangular channel under forced circulation was established based on the Subcooling number and Phase Change number. The oscillation periods were correlated with the fluid transit time and the boiling delay time. A flow pattern map for vertical upward flow in a mini-rectangular channel was applied to confirm the flow patterns during the oscillation. The mechanisms of the three types of instability were obtained by considering several types of flow instabilities and comparing them with the oscillations observed in this work. (author)

Analysis of cathode geometry to minimize cathode erosion in direct current microplasma jet

Energy Technology Data Exchange (ETDEWEB)

Causa, Federica [Dipartimento di Scienze dell' Ambiente, della Sicurezza, del Territorio, degli Alimenti e della Salute, Universita degli studi di Messina, 98122 Messina (Italy); Ghezzi, Francesco; Caniello, Roberto; Grosso, Giovanni [Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA-CNR Association, Via R. Cozzi 53, 20125 Milano (Italy); Dellasega, David [Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA-CNR Association, Via R. Cozzi 53, 20125 Milano (Italy); Dipartimento di Energia, Politecnico di Milano, Via Ponzio 34/3, 20133 Milano (Italy)

2012-12-15

Microplasma jets are now widely used for deposition, etching, and materials processing. The present study focuses on the investigation of the influence of cathode geometry on deposition quality, for microplasma jet deposition systems in low vacuum. The interest here is understanding the influence of hydrogen on sputtering and/or evaporation of the electrodes. Samples obtained with two cathode geometries with tapered and rectangular cross-sections have been investigated experimentally by scanning electron microscopy and energy dispersion X-ray spectroscopy. Samples obtained with a tapered-geometry cathode present heavy contamination, demonstrating cathode erosion, while samples obtained with a rectangular-cross-section cathode are free from contamination. These experimental characteristics were explained by modelling results showing a larger radial component of the electric field at the cathode inner wall of the tapered cathode. As a result, ion acceleration is larger, explaining the observed cathode erosion in this case. Results from the present investigation also show that the ratio of radial to axial field components is larger for the rectangular geometry case, thus, qualitatively explaining the presence of micro-hollow cathode discharge over a wide range of currents observed in this case. In the light of the above findings, the rectangular cathode geometry is considered to be more effective to achieve cleaner deposition.

Experimental study of falling water limitation under counter-current flow in the vertical rectangular channel

International Nuclear Information System (INIS)

Usui, Tohru; Kaminaga, Masanori; Sudo, Yukio.

1988-07-01

Quantitative understanding of critical heat flux (CHF) in the narrow vertical rectangular channel is required for the thermo-hydroulic design and the safety analysis of research reactors in which flat-plate-type fuel is adopted. Especially, critical heat flux under low downward velocity has a close relation with falling water limitation under counter-current flow. Accordingly, CCFL (Counter-current Flow Limitation) experiments were carried out for both vertical rectangular channels and vertical circular tubes varried in their size and configuration of their cross sections, to make clear CCFL characteristics in the vertical rectangular channels. In the experiments, l/de of the rectangular channel was changed from 3.5 to 180. As the results, it was clear that different equivalent hydraulic diameter de, namely width or water gap of channel, gave different CCFL characteristics of rectangular channel. But the influence of channel length l on CCFL characteristics was not observed. Besides, a dimensionless correlation to estimate a relation between upward air velocity and downward water velocity was proposed based on the present experimental results. The difference of CCFL characteristics between rectangular channels and circular tubes was also investigated. Especially for the rectangular channels, dry-patches appearing condition was made clear as a flow-map. (author)

Features of two-phase flow patterns in horizontal rectangular microchannels of height 50 μm

Directory of Open Access Journals (Sweden)

Ron’shin Fedor

2016-01-01

Full Text Available The horizontal microchannel with the height of 50 micrometres and width of 40 mm of a rectangular cross-section has been used to study two-phase flow. The classical patterns of two-phase flow in the channel (bubble, stratified, churn, jet, and annular have been detected. Experimental information allows us to define the characteristics of the regimes and to determine precisely the boundaries between the patterns of the two-phase flows.

Numerical study of turbulent flow in a rectangular T-junction

Science.gov (United States)

Georgiou, Michail; Papalexandris, Miltiadis V.

2017-06-01

In this paper, we report on a numerical study of the interaction and merging of a turbulent crossflow with an incoming turbulent jet in a T-junction with rectangular cross section. Our study is based on wall-resolved and experimentally validated large eddy simulations. The bulk Reynolds number of the crossflow is 15 000. Further, we consider cases with two different momentum ratios, namely, MR = 2 and MR = 0.5. In the presentation of the results, we elaborate on the main features of the flow, namely, the shear layers that emanate from the corners of the entry of the jet, the large recirculation bubble downstream the incoming jet, and the mixing process beyond the reattachment point. For validation purposes, we compare our simulations with existing experimental data. This comparison shows a good agreement between our numerical predictions and the measurements. First- and second-order statistics of the flow are also presented and analyzed in detail. Our simulations reveal two features of the flow that have not been reported before in studies of T-junctions. The first one is a secondary small-scale recirculation region between the entry of the jet and the large recirculation bubble. The second one is the negative turbulent kinetic energy production that occurs in the recirculation bubble and close to the reattachment of the flow. The analysis of our results further reveals that just across the entry of the jet, the boundary layer in the wall opposite to the jet experiences a favourable pressure gradient due to a Venturi effect induced by the incoming jet. In turn, this favourable pressure gradient contributes to the local relaminarization of the flow. On the other hand, the boundary layer downstream the recirculation bubble experiences an adverse pressure gradient. In both cases, a significant deviation from the universal law of the wall is confirmed.

Experimental Study of the Twin Turbulent Water Jets Using Laser Doppler Anemometry for Validating Numerical Models

International Nuclear Information System (INIS)

Wang Huhu; Lee Saya; Hassan, Yassin A.; Ruggles, Arthur E.

2014-01-01

The design of next generation (Gen. IV) high-temperature nuclear reactors including gas-cooled and sodium-cooled ones involves massive numerical works especially the Computational Fluid Dynamics (CFD) simulations. The high cost of large-scale experiments and the inherent uncertainties existing in the turbulent models and wall functions of any CFD codes solving Reynolds-averaged Navier-Stokes (RANS) equations necessitate the high-spacial experimental data sets for benchmarking the simulation results. In Gen. IV conceptual reactors, the high- temperature flows mix in the upper plenum before entering the secondary cooling system. The mixing condition should be accurately estimated and fully understood as it is related to the thermal stresses induced in the upper plenum and the magnitudes of output power oscillations due to any changes of primary coolant temperature. The purpose of this study is to use Laser Doppler Anemometry (LDA) technique to measure the flow field of two submerged parallel jets issuing from two rectangular channels. The LDA data sets can be used to validate the corresponding simulation results. The jets studied in this work were at room temperature. The turbulent characteristics including the distributions of mean velocities, turbulence intensities, Reynolds stresses were studied. Uncertainty analysis was also performed to study the errors involved in this experiment. The experimental results in this work are valid for benchmarking any steady-state numerical simulations using turbulence models to solve RANS equations. (author)

JET ITER-like wall—overview and experimental programme

International Nuclear Information System (INIS)

Matthews, G F; Beurskens, M; Loving, A; Kear, M; Mayoral, M-L; Prior, P; Riccardo, V; Watkins, M L; Brezinsek, S; Groth, M; Joffrin, E; Villedieu, E; Neu, R; Rimini, F; Sips, G; Rubel, M; De Vries, P

2011-01-01

This paper reports the successful installation of the JET ITER-like wall and the realization of its technical objectives. It also presents an overview of the planned experimental programme which has been optimized to exploit the new wall and other JET enhancements in 2011/12.

Two-phase flow in short horizontal rectangular microchannels with a height of 300 μm

Science.gov (United States)

Chinnov, E. A.; Ron'shin, F. V.; Kabov, O. A.

2015-09-01

The two-phase flow in a narrow short horizontal channel with a rectangular cross section is studied experimentally. The channel has a width of 10, 20, or 30 mm and a height of 300 μm. The specifics of formation of such two-phase flows are investigated. It is demonstrated that the regions of bubble and churn flow regimes grow and constrain the region of jet flow as the channel gets wider. The boundaries of the regions of annular and stratified flow regimes remain almost unaltered.

Experimental study on transition characteristics of pulsating flow in narrow rectangular channel

International Nuclear Information System (INIS)

Zhang Chuan; Tan Sichao; Liu Yusheng; Gao Puzhen; Zhao Jianing; Zhang Hong

2013-01-01

Experimental study of flow characteristic in smooth narrow rectangular channel under harmonic pulsating flow which covers laminar to turbulent flow (Reynolds number 7504-450) was carried out. The experimental results show that the frictional factors in acceleration phase of pulsating flow are higher than that in steady state, but lower than that in deceleration phase. Womersley parameter has a significant influence on the critical Reynolds number. The critical Reynolds number decreases with the increase of Womersley parameter in acceleration phase and it is opposite in deceleration phase. An empirical correlation was developed to predict the critical Reynolds number based on the experimental data, and the correlation can fit with critical Reynolds number in steady state. (authors)

A systematic study of supersonic jet noise.

Science.gov (United States)

Louis, J. F.; Letty, R. P.; Patel, J. R.

1972-01-01

The acoustic fields for a rectangular and for an axisymmetric nozzle configuration are studied. Both nozzles are designed for identical flow parameters. It is tried to identify the dominant noise mechanisms. The other objective of the study is to establish scaling laws of supersonic jet noise. A shock tunnel is used in the investigations. Measured sound directivity, propagation direction of Mach waves obtained by shadowgraphs, and the slight dependence of the acoustic efficiency on the level of expansion indicate that Mach waves contribute significantly to the noise produced by a rectangular jet.

Transverse acoustic forcing of a round hydrodynamically self-excited jet

Science.gov (United States)

Kushwaha, Abhijit Kumar; Mazur, Marek; Worth, Nicholas; Dawson, James; Li, Larry K. B.

2017-11-01

Hydrodynamically self-excited jets can readily synchronize with longitudinal acoustic forcing, but their response to transverse acoustic forcing is less clear. In this experimental study, we apply transverse acoustic forcing to an axisymmetric low-density jet at frequencies around its natural global frequency. We place the jet in a rectangular box containing two loudspeakers, one at each end, producing nominally one-dimensional standing pressure waves. By traversing the jet across this box, we subject it to a range of acoustic modes, from purely longitudinal (streamwise) modes at the pressure anti-node to purely transverse (cross-stream) modes at the pressure node. Using time-resolved Background-Oriented Schlieren (BOS) imaging and hot-wire anemometry, we characterize the jet response for different forcing frequencies, amplitudes and mode shapes, providing new insight into the way transverse acoustic oscillations interact with axisymmetric hydrodynamic oscillations. This work was supported by the Research Grants Council of Hong Kong (Project No. 16235716 and 26202815).

Experimental studies of unbiased gluon jets from $e^{+}e^{-}$ annihilations using the jet boost algorithm

CERN Document Server

Abbiendi, G.; Akesson, P.F.; Alexander, G.; Allison, John; Amaral, P.; Anagnostou, G.; Anderson, K.J.; Arcelli, S.; Asai, S.; Axen, D.; Azuelos, G.; Bailey, I.; Barberio, E.; Barlow, R.J.; Batley, R.J.; Bechtle, P.; Behnke, T.; Bell, Kenneth Watson; Bell, P.J.; Bella, G.; Bellerive, A.; Benelli, G.; Bethke, S.; Biebel, O.; Boeriu, O.; Bock, P.; Boutemeur, M.; Braibant, S.; Brigliadori, L.; Brown, Robert M.; Buesser, K.; Burckhart, H.J.; Campana, S.; Carnegie, R.K.; Caron, B.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Csilling, A.; Cuffiani, M.; Dado, S.; De Roeck, A.; De Wolf, E.A.; Desch, K.; Dienes, B.; Donkers, M.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Etzion, E.; Fabbri, F.; Feld, L.; Ferrari, P.; Fiedler, F.; Fleck, I.; Ford, M.; Frey, A.; Furtjes, A.; Gagnon, P.; Gary, John William; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Giunta, Marina; Goldberg, J.; Gross, E.; Grunhaus, J.; Gruwe, M.; Gunther, P.O.; Gupta, A.; Hajdu, C.; Hamann, M.; Hanson, G.G.; Harder, K.; Harel, A.; Harin-Dirac, M.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Hensel, C.; Herten, G.; Heuer, R.D.; Hill, J.C.; Hoffman, Kara Dion; Horvath, D.; Igo-Kemenes, P.; Ishii, K.; Jeremie, H.; Jovanovic, P.; Junk, T.R.; Kanaya, N.; Kanzaki, J.; Karapetian, G.; Karlen, D.; Kawagoe, K.; Kawamoto, T.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klein, K.; Klier, A.; Kluth, S.; Kobayashi, T.; Kobel, M.; Komamiya, S.; Kormos, Laura L.; Kramer, T.; Krieger, P.; von Krogh, J.; Kruger, K.; Kuhl, T.; Kupper, M.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Layter, J.G.; Leins, A.; Lellouch, D.; Letts, J.; Levinson, L.; Lillich, J.; Lloyd, S.L.; Loebinger, F.K.; Lu, J.; Ludwig, J.; Macpherson, A.; Mader, W.; Marcellini, S.; Martin, A.J.; Masetti, G.; Mashimo, T.; Mattig, Peter; McDonald, W.J.; McKenna, J.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Menges, W.; Merritt, F.S.; Mes, H.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Moed, S.; Mohr, W.; Mori, T.; Mutter, A.; Nagai, K.; Nakamura, I.; Nanjo, H.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oh, A.; Okpara, A.; Oreglia, M.J.; Orito, S.; Pahl, C.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poli, B.; Polok, J.; Pooth, O.; Przybycien, M.; Quadt, A.; Rabbertz, K.; Rembser, C.; Renkel, P.; Rick, H.; Roney, J.M.; Rosati, S.; Rozen, Y.; Runge, K.; Sachs, K.; Saeki, T.; Sarkisyan, E.K.G.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schieck, J.; Schoerner-Sadenius, Thomas; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Sherwood, P.; Siroli, G.; Skuja, A.; Smith, A.M.; Sobie, R.; Soldner-Rembold, S.; Spano, F.; Stahl, A.; Stephens, K.; Strom, David M.; Strohmer, R.; Tarem, S.; Tasevsky, M.; Taylor, R.J.; Teuscher, R.; Thomson, M.A.; Torrence, E.; Toya, D.; Tran, P.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turner-Watson, M.F.; Ueda, I.; Ujvari, B.; Vollmer, C.F.; Vannerem, P.; Vertesi, R.; Verzocchi, M.; Voss, H.; Vossebeld, J.; Waller, D.; Ward, C.P.; Ward, D.R.; Warsinsky, M.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wengler, T.; Wermes, N.; Wetterling, D.; Wilson, G.W.; Wilson, J.A.; Wolf, G.; Wyatt, T.R.; Yamashita, S.; Zer-Zion, D.; Zivkovic, Lidija

2004-01-01

We present the first experimental results based on the jet boost algorithm, a technique to select unbiased samples of gluon jets in e+e- annihilations, i.e. gluon jets free of biases introduced by event selection or jet finding criteria. Our results are derived from hadronic Z0 decays observed with the OPAL detector at the LEP e+e- collider at CERN. First, we test the boost algorithm through studies with Herwig Monte Carlo events and find that it provides accurate measurements of the charged particle multiplicity distributions of unbiased gluon jets for jet energies larger than about 5 GeV, and of the jet particle energy spectra (fragmentation functions) for jet energies larger than about 14 GeV. Second, we apply the boost algorithm to our data to derive unbiased measurements of the gluon jet multiplicity distribution for energies between about 5 and 18 GeV, and of the gluon jet fragmentation function at 14 and 18 GeV. In conjunction with our earlier results at 40 GeV, we then test QCD calculations for the en...

Numerical and experimental study of two turbulent opposed plane jets

Energy Technology Data Exchange (ETDEWEB)

Besbes, Sonia; Mhiri, Hatem [Laboratoire de Mecanique des Fluides et Thermique, Ecole Nationale d' Ingenieurs de Monastir, Route de Ouardanine, Monastir (Tunisia); Le Palec, Georges; Bournot, Philippe [Institut de Mecanique de Marseille, UNIMECA, Technopole de Chateau-Gombert, 60 rue Joliot-Curie, 13453 Marseille (France)

2003-09-01

The turbulent interaction between two opposed plane jets separated by a distance H is experimentally studied by using a PIV (Particle Image Velocimetry) method and numerically investigated by means of a finite volume code. Two turbulence models have been tested: the standard k-{epsilon} model and a second-order model. The validation of the numerical study was performed by comparing the results with experimental data obtained for the case of two interacting opposed jets at ambient temperature (isothermal case). The effect of the angle of inclination of the jets is studied. Conclusions of the validation are then used to study the interaction between two jets, one being maintained at ambient temperature whereas the other is heated. Results show that the stagnation point moves towards the heated jet. It is shown that the heating induces a stabilizing effect on the flow. (orig.)

Influence of the Reynolds number on the instant flow evolution of a turbulent rectangular free jet of air

International Nuclear Information System (INIS)

Gori, Fabio; Petracci, Ivano; Angelino, Matteo

2014-01-01

Highlights: • Flow with Negligible Disturbances, or first type, with length L ND = L 1 . • Flow with Small Disturbances, or second type, with length L SD . • Total length, L ND + L SD = L 2 , is in agreement with average Undisturbed flow, L U . • Flow with Coherent Vortices, or third type, with length L CV . • Total length, L ND + L SD + L CV = L 3 , is in agreement with average Potential core, L P . - Abstract: The paper is aimed at investigating the influence of the Reynolds number on the instant flow evolution of a rectangular free jet of air in the range of Reynolds numbers from Re = 35,300 to Re = 2,200, where the Reynolds number, Re, is defined according to the hydraulic diameter, D, of a rectangular slot of height H, equal to about D = 2H. The Particle Image Velocimetry (PIV) technique allows obtaining the instant PIV visualizations on the central symmetry section of the rectangular jet. The visual inspection of the instant frames with one and two vortices, except for Re = 35,300 where only one vortex images are detected, shows that after the jet exit is present the Flow with Constant Instant Height, with a length L CIH which increases with the decrease of the Reynolds number, from a ratio L CIH /H equal to L CIH /H = 0.9 at Re = 35,300 to L CIH /H = 4.0 at Re = 2,200. The instant PIV measurements, carried out at several distances from the jet exit, show that the variations of the ratio U/U ‾ 0 of the centerline instant velocity, U, to the exit average velocity, U ‾ 0 , remain below ±4% for a length L CIV , defining the Flow with Constant Instant Velocity on the centerline. The ratio L CIV /H increases from L CIV /H = 1.1 at Re = 35,300 to L CIV /H = 4.1 at Re = 2,200 and is quite similar to L CIH /H. The instant PIV measurements of the centerline turbulence intensity, Tu, show that its variations remain below ±4% for a length L CIT , defining the Flow with Constant Instant Turbulence on the centerline. The ratio L CIT /H is equal to L CIV /H

Cooling of rectangular bars

International Nuclear Information System (INIS)

Frainer, V.J.

1979-01-01

A solution of the time-transient Heat Transfer Differential Equation in rectangular coordinates is presented, leading to a model which describes the temperature drop with time in rectangular bars. It is similar to an other model for cilindrical bars which has been previously developed in the Laboratory of Mechanical Metallurgy of UFRGS. Following these models, a generalization has been made, which permits cooling time evaluation for all profiles. These results are compared with experimental laboratory data in the 1200 to 800 0 C range. Some other existing models were also studied which have the purpose of studing the same phenomenon. Their mathematical forms and their evaluated values are analyzed and compared with experimental ones. (Author) [pt

Experimental study on performance of pulsed liquid jet pump

International Nuclear Information System (INIS)

Xu Weihui; Gao Chuanchang; Qin Haixia

2010-01-01

The device performance characteristics of transformer type pulsed liquid pump device were experimentally studied. The effects of the area ratio, work pressure and pulse parameters on the performance of the pulsed liquid jet pump device were performed in the tests. The potency of pulsed jet on improving the performance of the liquid jet pump device was also studied through the comparison with invariable jet pump at the same conditions. The results show that the pulsed jet can significantly improve the performance of transformer type jet pump devices. Area ratio and pulse parameters are the critical factors to the performance of the pulsed liquid jet pump device. The jet pump device performances are significantly improved by reducing the area ratio or by increasing the pulsed frequency. The flux characteristics of the pulsed liquid jet pump device presents the typical negative linear,the potency of pulsed jet in improving the performance of jet pump device with small area ratio can be more significant. The efficiency curve of pulsed liquid jet pump is similar to the parabola. At higher pulsed frequency, the top efficiency point of the pulsed jet pump moves to the higher flow ratio. The high efficiency area of the pulsed jet pump also is widened with the increase of the pulsed frequency. (authors)

Comparison of CFD simulations with experimental Jet Erosion Tests results

OpenAIRE

Mercier, F.; Bonelli, S.; Pinettes, P.; Golay, F.; Anselmet, F.; Philippe, P.

2014-01-01

The Jet Erosion Test (JET) is an experimental device increasingly used to quantify the resistance of soils to erosion. This resistance is characterised by two geotechnical parameters: the critical shear stress and the erosion coefficient. The JET interpretation model of Hanson and Cook (2004) provides an estimation of these erosion parameters. But Hanson's model is simplified, semi-empirical and several assumed hypotheses can be discussed. Our aim is to determine the relevance of the JET inte...

Aeroacoustics of rectangular T-junctions subject to combined grazing and bias flows - An experimental investigation

Science.gov (United States)

Holmberg, Andreas; Karlsson, Mikael; Åbom, Mats

2015-03-01

Scattering matrices are determined experimentally and used to study the low-amplitude interaction, between the acoustic and the hydrodynamic fields in a T-junction of rectangular ducts. In particular, combinations of grazing and bias flows are investigated in the study. It is observed that for all flow combinations, waves incident on the junction at the downstream side only are attenuated, while waves incident at the other branches may be amplified or attenuated, depending on the Strouhal number. When bias in-flow is introduced to a grazing flow, there is first an increase and then a decrease in both amplification and attenuation, as the bias in-flow Mach number is increased. Comparing with T-junctions of circular ducts, the interaction is stronger for rectangular duct junctions.

hydrodynamic behavior of particles in a Jet flow of a gas fluidized bed

International Nuclear Information System (INIS)

Mirmomen, L.; Alavi, M.

2005-01-01

Numerous investigations have been devoted towards understanding the hydrodynamics of gas jets in fluidized beds. However, most of them address the problem from macroscopic point of view, which does not reveal the true behavior in the jet region at the single particle level. The present work aims to understand the jet behavior from a more fundamental level, i.e. the individual particle level. A thin rectangular gas fluidized bed, constructed from acrylic glass, with a vertical jet nozzle located at the center of the distributor was used in the work. A high speed camera with a speed up to 10,000 frames per second was used to observe the jet behavior . Analysis of large quantity of images allowed determination of solids flux, solids Velocity and solids concentration in the jet region . The model present in this work has shown better agreement with the experimental data in compare with the previous models presented in the literature

Burnout in a high heat flux boiling system with forced supply of liquid through a plane jet

International Nuclear Information System (INIS)

Katto, Yoshiro; Ishii, Kazunori.

1978-01-01

As for pool boiling, the non-dimensional formula for the burnout heat flux of a simple, basic boiling system has been obtained. On the other hand, in forced convection boiling, the studies on the burnout in forced flow boiling in a channel have been continued, but the derivation of a non-dimensional formula applicable generally is far away from the realization because the phenomena are too complex. Accordingly, in this study, the result of the experiment on the burnout of a boiling system to which liquid is supplied by the plane jet flowing out of a thin rectangular nozzle installed near the front edge of a rectangular heating surface is reported. The experimental apparatus is described, and the experiment was carried out in the ranges of two jet thicknesses at the nozzle outlet, two incident angles of jet and from 1.5 to 15 m/s of jet velocity. Burnout occurs under the situation of sufficiently developed nuclear boiling. A part of the liquid supplied from a plane jet is blown apart by the vapor blowing out of the nuclear boiling liquid layer covering the heating surface in the nuclear boiling with sufficiently developed high heat flux. However, the nuclear boiling liquid layer itself continues to exist on the heating surface till burnout occurs. Only the entering velocity of the plane jet affects burnout heat flux. (Kako, I.)

Pitot-Pressure Measurements in Flow Fields Behind a Rectangular Nozzle with Exhaust Jet for Free-Stream Mach Numbers of 0.00, 0.60, and 1.20

Science.gov (United States)

Putnam, L. E.; Mercer, C. E.

1986-01-01

An investigation has been conducted in the Langley 16-Foot Transonic Tunnel to measure the flow field in and around the jet exhaust from a nonaxisymmetric nozzle configuration. The nozzle had a rectangular exit with a width-to-height ratio of 2.38. Pitot-pressure measurements were made at five longitudinal locations downstream of the nozzle exit. The maximum distance downstream of the exit was about 5 nozzle heights. These measurements were made at free-stream Mach numbers of 0.00, 0.60, and 1.20 with the nozzle operating at a ratio of nozzle total pressure to free-stream static pressure of 4.0. The jet exhaust was simulated with high-pressure air that had an exit total temperature essentially equal to the free-stream total temperature.

Measurements of time-dependent liquid-metal magnetohydrodynamic flows in a flat rectangular duct

International Nuclear Information System (INIS)

Buehler, L.; Horanyi, S.

2009-01-01

In the helium-cooled lead lithium (HCLL) blanket, which has been chosen as a reference concept for a liquid-metal breeding blanket to be tested in ITER, the heat is removed by helium cooled plates aligned with the strong toroidal magnetic field that confines the fusion plasma. The liquid breeder lead lithium circulates through gaps of rectangular cross-section between the cooling plates to transport the generated tritium towards external extraction facilities. Under the action of the strong magnetic field, liquid metal flows in conducting rectangular ducts exhibit jet-like velocity profiles in the thin boundary layers near the side walls, which are parallel to the magnetic field like the cooling plates in HCLL blankets. The velocity in these side layers may exceed several times the mean velocity in the duct and it is known that these layers become unstable for sufficiently high Reynolds numbers. The present paper summarizes experimental results for such unstable time-dependent flows in strong magnetic fields, which have been obtained in the MEKKA liquid metal laboratory of the Forschungszentrum Karlsruhe. In particular, spatial and temporal scales of perturbation patterns are identified. The results suggest that the flow between cooling plates in a HCLL blanket is laminar and stable. The observed time-dependent flow behavior appears at larger velocities so that the present results are more relevant for applications in dual coolant concepts where high-velocity jets have been predicted along side walls.

Screech Tones from Rectangular Jets with Spanwise Oblique Shock-Cell Structures

Science.gov (United States)

Raman, Ganesh

1996-01-01

Understanding screech is especially important for the design of advanced aircraft because screech can cause sonic fatigue failure of aircraft structures. Although the connection between shock-cell spacing and screech frequency is well understood, the relation between non-uniformities in the shock-cell structures and the resulting amplitude, mode, and steadiness of screech have remained unexplored. This paper addresses the above issues by intentionally producing spanwise (larger nozzle dimension) variations in the shock-cell structures and studying the resulting spanwise screech mode. The spanwise oblique shock-cell structures were produced using imperfectly expanded convergent-divergent rectangular nozzles (aspect ratio = 5) with nonuniform exit geometries. Three geometries were studied: (a) a nozzle with a spanwise uniform edge, (b) a nozzle with a spanwise oblique (single bevelled) edge, and (c) a nozzle that had two spanwise oblique (double bevelled) cuts to form an arrowhead-shaped nozzle. For all nozzles considered, the screech mode was antisymmetric in the transverse (smaller nozzle dimension) direction allowing focus on changes in the spanwise direction. Three types of spanwise modes were observed: symmetric (1), antisymmetric (2), and oblique (3). The following significant results emerged: (1) for all cases the screech mode corresponds with the spanwise shock-cell structure, (2) when multiple screech modes are present, the technique presented here makes it possible to distinguish between coexisting and mutually exclusive modes, (3) the strength of shocks 3 and 4 influences the screech source amplitude and determines whether screech is unsteady. The results presented here offer hope for a better understanding of screech and for tailoring shock-containing jets to minimize fatigue failure of aircraft components.

Computed and experimental motion picture determination of bubble and solids motion in a two-dimensional fluidized-bed with a jet and immersed obstacle

International Nuclear Information System (INIS)

Lyczkowski, R.W.; Bouillard, J.; Gidaspow, D.

1986-01-01

Bubble and solids motion in a two-dimensional rectangular fluidized-bed having a high speed central jet with a rectangular obstacle above it and secondary air flow at minimum fluidization have been computer modeled. Computer generated motion pictures have been found to be necessary to analyze the computations since there are such a large number of time-dependent complex phenomena difficult to comprehend otherwise. Comparison of the computer generated motion pictures with high speed motion pictures of a flow visualization experiment reveal good agreement

Experimental and numerical study on density stratification erosion phenomena with a vertical buoyant jet in a small vessel

Energy Technology Data Exchange (ETDEWEB)

Abe, Satoshi, E-mail: abe.satoshi@jaea.go.jp; Ishigaki, Masahiro; Sibamoto, Yasuteru; Yonomoto, Taisuke

2016-07-15

Highlights: • This paper shows results of a small scale experiment and CFD analyses on a density stratification erosion with a vertical buoyant jet. • The particle image velocimetry (PIV) and quadrupole mass spectrometer (QMS) with a multiport rotating valve were applied. • Two typical well-used RANS models were applied. • The simulated stratification erosion was in agreement with the experimental result, which suggested that the turbulence mixing occurred only in the jet impinging region. - Abstract: The Japan Atomic Energy Agency (JAEA) has started the ROSA-SA project to investigate thermal hydraulic phenomena in a reactor containment vessel during a severe accident. The hydrogen distribution in the vessel is one of significant safety issues in discussing a potential of hydrogen combustion in the containment. Density stratification and its break-up are important phenomena affecting the hydrogen distribution. This paper focuses on a density stratification erosion and break-up mechanism with a vertical buoyant jet promoting the turbulent helium transport. Small scale experiment and computational fluid dynamics (CFD) analyses were carried out for investigating this phenomena. In the experiment, a rectangular vessel made with acrylic plates with a width of 1.5 m, a length of 1.5 m and a height of 1.8 m was used for visualizing flow field with particle image velocimetry (PIV) system. The quadrupole mass spectrometer (QMS) system with a multiport rotating valve was applied for measuring gaseous concentration at 20 elevation points. In CFD analysis with OpenFOAM, two typical well-used turbulence models were used: low-Reynolds number type k–ε model and SST k–ω model, with a turbulence model modification to consider the buoyant effect in the stratification. As a result, the stratification erosion in the CFD analyses with the modified turbulence model agreed well with the experimental data, indicating importance of the turbulence damping by the buoyant effect.

Experimental and numerical study on density stratification erosion phenomena with a vertical buoyant jet in a small vessel

International Nuclear Information System (INIS)

Abe, Satoshi; Ishigaki, Masahiro; Sibamoto, Yasuteru; Yonomoto, Taisuke

2016-01-01

Highlights: • This paper shows results of a small scale experiment and CFD analyses on a density stratification erosion with a vertical buoyant jet. • The particle image velocimetry (PIV) and quadrupole mass spectrometer (QMS) with a multiport rotating valve were applied. • Two typical well-used RANS models were applied. • The simulated stratification erosion was in agreement with the experimental result, which suggested that the turbulence mixing occurred only in the jet impinging region. - Abstract: The Japan Atomic Energy Agency (JAEA) has started the ROSA-SA project to investigate thermal hydraulic phenomena in a reactor containment vessel during a severe accident. The hydrogen distribution in the vessel is one of significant safety issues in discussing a potential of hydrogen combustion in the containment. Density stratification and its break-up are important phenomena affecting the hydrogen distribution. This paper focuses on a density stratification erosion and break-up mechanism with a vertical buoyant jet promoting the turbulent helium transport. Small scale experiment and computational fluid dynamics (CFD) analyses were carried out for investigating this phenomena. In the experiment, a rectangular vessel made with acrylic plates with a width of 1.5 m, a length of 1.5 m and a height of 1.8 m was used for visualizing flow field with particle image velocimetry (PIV) system. The quadrupole mass spectrometer (QMS) system with a multiport rotating valve was applied for measuring gaseous concentration at 20 elevation points. In CFD analysis with OpenFOAM, two typical well-used turbulence models were used: low-Reynolds number type k–ε model and SST k–ω model, with a turbulence model modification to consider the buoyant effect in the stratification. As a result, the stratification erosion in the CFD analyses with the modified turbulence model agreed well with the experimental data, indicating importance of the turbulence damping by the buoyant effect.

Deformation of current-carrying jets by nonviscous electrically conducting fluid

International Nuclear Information System (INIS)

Morozova, V.I.

1986-01-01

The change in the form of the transverse cross section of the jet under the action of the current flowing along it is investigated. The reults of computations for solitary current carrying jets of square and rectangular cross sections, and for systems of six and twelve azimuthally periodic jets with currents alternating in direction, are shown in figures. A solitary jet with square transverse cross section at the initial instant executes a periodic motion involving transition from square cross section, through circular, back to square rotated by 45 0 with respect to the initial section, and later going through circular cross section and returning to the initial position is shown in a figure. Other figures show similar deformations occuring with a solitary rectangular cross section, and deformations of the systems of jets which are accompanied by their radial separation. The authors note that the present formulation uses only geometric criteria of similarity; therefore the dependences of the deformations on time, presented in figures, are universal

Rectangular-section mirror light pipes

Energy Technology Data Exchange (ETDEWEB)

Swift, P.D.; Lawlor, R. [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland); Smith, G.B.; Gentle, A. [Department of Applied Physics, University of Technology, Sydney, Broadway, NSW 2007 (Australia)

2008-08-15

Using an integrated-ray approach an expression for the transmission of rectangular section mirror light pipe (MLP) has been derived for the case of collimated light input. The transmittance and the irradiance distribution at the exit aperture of rectangular-section MLPs have been measured experimentally and calculated theoretically for the case of collimated light input. The results presented extend the description of MLPs from the cylindrical case. Measured and calculated transmittances and irradiance distributions are in good agreement. (author)

Numerical and Experimental Analysis on the Cavity Formation and Shrinkage for Investment Cast Alloy 738 4 mm-Thick Rectangular Tube

International Nuclear Information System (INIS)

Park, Myeong-Il; Choi, Yoon Suk; Yoo, Jae-Hyun; Park, Sang-Hu; Kim, Kyeong-Min; Lee, Yeong-Chul; Lee, Jung-Seok; Lee, Jae-Hyun

2017-01-01

Investment casting for the thin (4 mm thick) rectangular tube (40 mm wide, 80 mm high and 200 mm long) was carried out numerically and experimentally for Alloy 738, which is a precipitation-hardened Ni-base superalloy. Two types of rectangular tubes, one with a regular array (10 mm by 10 mm square array) of protruded rods (3 mm in diameter and 3mm in height) embedded on the outer surface and the other with just smooth surface, were investment-cast at the same time through the side feeding mold design. The investment casting simulation predicted the presence of cavities, particularly in the area away from the gate for both types of rectangular tubes. In particular, for the rectangular tube with embedded protruded rods cavities were found mainly in the areas between the protruded rods. This simulation result was qualitatively consistent with the experimental observation from the X-ray analysis. Also, both prediction and experiment showed that the dimensional shrinkage (particularly in the longitudinal direction) of the investment-cast rectangular tube is reduced by having protruded rods embedded on the outer surface. Additional numerical attempts were made to check how the amount of cavities and dimensional shrinkage change by varying the preheating temperature and the thickness of the mold. The results predicted that the amount of cavities and the dimensional shrinkage are significantly reduced by increasing the preheating temperature of the mold by 200 ℃. However, an increase in mold thickness from 10 mm to 12 mm showed almost no difference in cavity population and a slight decrease in dimensional shrinkage.

Numerical and Experimental Analysis on the Cavity Formation and Shrinkage for Investment Cast Alloy 738 4 mm-Thick Rectangular Tube

Energy Technology Data Exchange (ETDEWEB)

Park, Myeong-Il; Choi, Yoon Suk; Yoo, Jae-Hyun; Park, Sang-Hu [Pusan National University, Busan (Korea, Republic of); Kim, Kyeong-Min; Lee, Yeong-Chul [Sung Il Turbine Co., Ltd., Busan (Korea, Republic of); Lee, Jung-Seok; Lee, Jae-Hyun [Changwon National University, Changwon (Korea, Republic of)

2017-02-15

Investment casting for the thin (4 mm thick) rectangular tube (40 mm wide, 80 mm high and 200 mm long) was carried out numerically and experimentally for Alloy 738, which is a precipitation-hardened Ni-base superalloy. Two types of rectangular tubes, one with a regular array (10 mm by 10 mm square array) of protruded rods (3 mm in diameter and 3mm in height) embedded on the outer surface and the other with just smooth surface, were investment-cast at the same time through the side feeding mold design. The investment casting simulation predicted the presence of cavities, particularly in the area away from the gate for both types of rectangular tubes. In particular, for the rectangular tube with embedded protruded rods cavities were found mainly in the areas between the protruded rods. This simulation result was qualitatively consistent with the experimental observation from the X-ray analysis. Also, both prediction and experiment showed that the dimensional shrinkage (particularly in the longitudinal direction) of the investment-cast rectangular tube is reduced by having protruded rods embedded on the outer surface. Additional numerical attempts were made to check how the amount of cavities and dimensional shrinkage change by varying the preheating temperature and the thickness of the mold. The results predicted that the amount of cavities and the dimensional shrinkage are significantly reduced by increasing the preheating temperature of the mold by 200 ℃. However, an increase in mold thickness from 10 mm to 12 mm showed almost no difference in cavity population and a slight decrease in dimensional shrinkage.

Experimental and analytical studies of melt jet-coolant interactions: a synthesis

Energy Technology Data Exchange (ETDEWEB)

Dinh, T.N.; Bui, V.A.; Nourgaliev, R.R.; Green, J.A.; Sehgal, B.R. [Royal Inst. of Tech., Stockholm (Sweden). Div. of Nuclear Power Safety

1998-01-01

Instability and fragmentation of a core melt jet in water have been actively studied during the past ten years. Several models, and a few computer codes, have been developed. However, there are, still, large uncertainties, both, in interpreting experimental results and in predicting reactor-scale processes. Steam explosion and debris coolability, as reactor safety issues, are related to the jet fragmentation process. A better understanding of the physics of jet instability and fragmentation is crucial for assessments of fuel-coolant interactions (FCIs). This paper presents research, conducted at the Division of Nuclear Power Safety, Royal Institute of Technology (RIT/NPS), Stockholm, concerning molten jet-coolant interactions, as a precursor for premixing. First, observations were obtained from scoping experiments with simulant fluids. Second, the linear perturbation method was extended and applied to analyze the interfacial-instability characteristics. Third, two innovative approachs to CFD modeling of jet fragmentation were developed and employed for analysis. The focus of the studies was placed on (a) identifying potential factors, which may affect the jet instability, (b) determining the scaling laws, and (c) predicting the jet behavior for severe accidents conditions. In particular, the effects of melt physical properties, and the thermal hydraulics of the mixing zone, on jet fragmentation were investigated. Finally, with the insights gained from a synthesis of the experimental results and analysis results, a new phenomenological concept, named `macrointeractions concept of jet fragmentation` is proposed. (author)

Experimental and analytical studies of melt jet-coolant interactions: a synthesis

International Nuclear Information System (INIS)

Dinh, T.N.; Bui, V.A.; Nourgaliev, R.R.; Green, J.A.; Sehgal, B.R.

1999-01-01

Instability and fragmentation of a core melt jet in water have been actively studied during the past 10 years. Several models, and a few computer codes, have been developed. However, there are, still, large uncertainties, both, in interpreting experimental results and in predicting reactor-scale processes. Steam explosion and debris coolability, as reactor safety issues, are related to the jet fragmentation process. A better understanding of the physics of jet instability and fragmentation is crucial for assessments of fuel-coolant interactions (FCIs). This paper presents research, conducted at the Division of Nuclear Power Safety, Royal Institute of Technology (RIT/NPS), Stockholm, concerning molten jet-coolant interactions, as a precursor for premixing. First, observations were obtained from scoping experiments with simulant fluids. Second, the linear perturbation method was extended and applied to analyze the interfacial-instability characteristics. Third, two innovative approaches to computational fluid dynamics (CFD) modeling of jet fragmentation were developed and employed for analysis. The focus of the studies was placed on (a) identifying potential factors, which may affect the jet instability, (b) determining the scaling laws, and (c) predicting the jet behavior for severe accident conditions. In particular, the effects of melt physical properties, and the thermal hydraulics of the mixing zone, on jet fragmentation were investigated. Finally, with the insights gained from a synthesis of the experimental results and analysis results, a new phenomenological concept, named 'macrointeractions concept of jet fragmentation' is proposed. (orig.)

Rectangular maximum-volume submatrices and their applications

KAUST Repository

Mikhalev, Aleksandr; Oseledets, I.V.

2017-01-01

We introduce a definition of the volume of a general rectangular matrix, which is equivalent to an absolute value of the determinant for square matrices. We generalize results of square maximum-volume submatrices to the rectangular case, show a connection of the rectangular volume with an optimal experimental design and provide estimates for a growth of coefficients and an approximation error in spectral and Chebyshev norms. Three promising applications of such submatrices are presented: recommender systems, finding maximal elements in low-rank matrices and preconditioning of overdetermined linear systems. The code is available online.

Rectangular maximum-volume submatrices and their applications

KAUST Repository

Mikhalev, Aleksandr

2017-10-18

We introduce a definition of the volume of a general rectangular matrix, which is equivalent to an absolute value of the determinant for square matrices. We generalize results of square maximum-volume submatrices to the rectangular case, show a connection of the rectangular volume with an optimal experimental design and provide estimates for a growth of coefficients and an approximation error in spectral and Chebyshev norms. Three promising applications of such submatrices are presented: recommender systems, finding maximal elements in low-rank matrices and preconditioning of overdetermined linear systems. The code is available online.

Experimental approaches for studying non-equilibrium atmospheric plasma jets

Energy Technology Data Exchange (ETDEWEB)

Shashurin, A., E-mail: ashashur@purdue.edu [School of Aeronautics & Astronautics, Purdue University, West Lafayette, Indiana 47907 (United States); Keidar, M. [Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, District of Columbia 20052 (United States)

2015-12-15

This work reviews recent research efforts undertaken in the area non-equilibrium atmospheric plasma jets with special focus on experimental approaches. Physics of small non-equilibrium atmospheric plasma jets operating in kHz frequency range at powers around few Watts will be analyzed, including mechanism of breakdown, process of ionization front propagation, electrical coupling of the ionization front with the discharge electrodes, distributions of excited and ionized species, discharge current spreading, transient dynamics of various plasma parameters, etc. Experimental diagnostic approaches utilized in the field will be considered, including Rayleigh microwave scattering, Thomson laser scattering, electrostatic streamer scatterers, optical emission spectroscopy, fast photographing, etc.

PIV and LIF study of slot continuous jet at low Reynolds number

Directory of Open Access Journals (Sweden)

Broučková Zuzana

2016-01-01

Full Text Available This study deals with a continuous jet issuing from a small narrow slot with a width of 0.36 mm. The experimental arrangement is based on the piezoelectric synthetic jet actuator studied previously for easy comparisons. The working fluid is water at room temperature. The experiments were performed using methods of particle image velocimetry (PIV and flow visualization (laser induced fluorescence, LIF. The time-mean volume flux through the exit nozzle was quantified using precise scales. The mean velocity and the Reynolds number were evaluated as Um = 0.12 m/s and Re = 90, respectively. The results of LIF and PIV techniques revealed the three-dimensional character of the flow field, namely the saddle-shape velocity profiles. This behavior is typical for steady jets from a rectangular nozzle. The obtained results were compared with previous measurements of the synthetic jet issuing from the same cavity and the slot nozzle.

Experimental study on saturated boiling of two phase natural circulation under low pressure in narrow rectangular channels

Energy Technology Data Exchange (ETDEWEB)

Li, Zi-chao; Qi, Shi; Zhou, Tao; Li, Bing; Shahzad, Muhammad Ali [North China Electric Power Univ., Beijing (China). School of Nuclear Science and Engineering; Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy, Beijing (China); Huang, Yan-ping [Nuclear Reactor Thermal Hydraulics Technology, Chengdu (China). CNNC Key Lab.

2017-12-15

Saturated boiling of two-phase natural circulation has been experimentally investigated based on a natural circulation device with narrow rectangular channels. When heating power reaches a certain range, it is possible to observe the phenomenon of saturated boiling and flow pattern transition in the system. The results show the heat transfer coefficient of saturated boiling decreases with the increasing of pressure, heating power and size of narrow rectangle channels. The buoyancy force causing mixed convection decreases the heat transfer coefficient. Finally, a dimensionless number is introduced, which reflects length to width ratio of rectangular narrow section and Rayleigh number, in order to revise the presented correlation. All errors fall within the range of ±15%.

Experimental investigation of submerged single jet impingement using Cu–water nanofluid

International Nuclear Information System (INIS)

Li Qiang; Xuan Yimin; Yu Feng

2012-01-01

Jet impingement cooling is a vital technique for thermal management of electronic devices of high-heat-flux by impinging fluid on a heater surface due to its high local heat transfer rates. In this paper, two types of Cu–water nanofluids (Cu particles with 25 nm diameter or 100 nm) are introduced into submerged single jet impingement cooling system as the working fluid. The heat transfer features of the nanofluids were experimentally investigated. The effects of the nanoparticle concentration, Reynolds number, nozzle-to-plate distance, fluid temperature, and nanoparticle diameter on the heat transfer performances of the jet impingement of nanofluids are discussed. The experimental results show that the suspended nanoparticles remarkably increase the convective heat transfer coefficient of the base fluid. The convective heat transfer coefficient of Cu–water nanofluid with the volume fraction of 3.0% has 52% higher than the pure water. The experiments also revealed that the suspended nanoparticles brought almost no extra addition of pressure drop in both submerged single jet impingement. In addition, by considering the effects of the suspended nanoparticles as well as the condition of impinging jet, a new heat transfer correlation of nanofluids for the submerged single jet impingement has been proposed. - Highlights: ► Cu–water nanofluids are introduced into submerged single jet impingement. ► The affecting parameters on the heat transfer performances of nanofluids are discussed. ► New heat transfer correlation of nanofluid for single jet impingement is proposed.

An experimental and theoretical investigation of spray characteristics of impinging jets in impact wave regime

Science.gov (United States)

Rodrigues, N. S.; Kulkarni, V.; Gao, J.; Chen, J.; Sojka, P. E.

2015-03-01

The current study focuses on experimentally and theoretically improving the characterization of the drop size and drop velocity for like-on-like doublet impinging jets. The experimental measurements were made using phase Doppler anemometry (PDA) at jet Weber numbers We j corresponding to the impact wave regime of impinging jet atomization. A more suitable dynamic range was used for PDA measurements compared to the literature, resulting in more accurate experimental measurements for drop diameters and velocities. There is some disagreement in the literature regarding the ability of linear stability analysis to accurately predict drop diameters in the impact wave regime. This work seeks to provide some clarity. It was discovered that the assumed uniform jet velocity profile was a contributing factor for deviation between diameter predictions based on models in the literature and experimental measurements. Analytical expressions that depend on parameters based on the assumed jet velocity profile are presented in this work. Predictions based on the parabolic and 1/7th power law turbulent profiles were considered and show better agreement with the experimental measurements compared to predictions based on the previous models. Experimental mean drop velocity measurements were compared with predictions from a force balance analysis, and it was observed that the assumed jet velocity profile also influences the predicted velocities, with the turbulent profile agreeing best with the experimental mean velocity. It is concluded that the assumed jet velocity profile has a predominant effect on drop diameter and velocity predictions.

Large-eddy simulation of cavitating nozzle flow and primary jet break-up

Energy Technology Data Exchange (ETDEWEB)

Örley, F., E-mail: felix.oerley@aer.mw.tum.de; Trummler, T.; Mihatsch, M. S.; Schmidt, S. J.; Adams, N. A. [Institute of Aerodynamics and Fluid Mechanics, Technische Universität München, Boltzmannstr. 15, 85748 Garching bei München (Germany); Hickel, S. [Institute of Aerodynamics and Fluid Mechanics, Technische Universität München, Boltzmannstr. 15, 85748 Garching bei München (Germany); Chair of Computational Aerodynamics, Faculty of Aerospace Engineering, TU Delft, Kluyverweg 1, 2629 HS Delft (Netherlands)

2015-08-15

We employ a barotropic two-phase/two-fluid model to study the primary break-up of cavitating liquid jets emanating from a rectangular nozzle, which resembles a high aspect-ratio slot flow. All components (i.e., gas, liquid, and vapor) are represented by a homogeneous mixture approach. The cavitating fluid model is based on a thermodynamic-equilibrium assumption. Compressibility of all phases enables full resolution of collapse-induced pressure wave dynamics. The thermodynamic model is embedded into an implicit large-eddy simulation (LES) environment. The considered configuration follows the general setup of a reference experiment and is a generic reproduction of a scaled-up fuel injector or control valve as found in an automotive engine. Due to the experimental conditions, it operates, however, at significantly lower pressures. LES results are compared to the experimental reference for validation. Three different operating points are studied, which differ in terms of the development of cavitation regions and the jet break-up characteristics. Observed differences between experimental and numerical data in some of the investigated cases can be caused by uncertainties in meeting nominal parameters by the experiment. The investigation reveals that three main mechanisms promote primary jet break-up: collapse-induced turbulent fluctuations near the outlet, entrainment of free gas into the nozzle, and collapse events inside the jet near the liquid-gas interface.

Experimental study and numerical simulation of free pulsed jets; Etude experimentale et modelisation numerique des jets libres pulses

Energy Technology Data Exchange (ETDEWEB)

Marzouk, Salwa; Mhiri, Hatem [Ecole Nationale d' Ingenieurs de Monastir, Lab. de Mecanique des Fluides et Thermique, Monastir (Tunisia); Caminat, Ph.; Le Palec, G.; Bournot, Ph. [UNIMECA, 13 - Marseille (France)

2001-07-01

A plane pulsed jet flow has been simulated by a finite difference method. Experimental results have also been obtained by laser tomography and particle image velocimetry. The results show that the flow is affected by the pulsation in the vicinity of the nozzle to reach an asymptotic state of a permanent jet. (A.L.B.)

Flow evolution of a turbulent submerged two-dimensional rectangular free jet of air. Average Particle Image Velocimetry (PIV) visualizations and measurements

International Nuclear Information System (INIS)

Gori, Fabio; Petracci, Ivano; Angelino, Matteo

2013-01-01

Highlights: • Zone of flow establishment contains a newly identified undisturbed region of flow. • In the undisturbed region of flow the velocity profile is similar to the exit one. • In undisturbed region of flow the height of average PIV visualizations is constant. • In the undisturbed region of flow the turbulence on the centerline is equal to exit. • Length of undisturbed region of flow decreases with Reynolds number increase. -- Abstract: The paper presents average flow visualizations and measurements, obtained with the Particle Image Velocimetry (PIV) technique, of a submerged rectangular free jet of air in the range of Reynolds numbers from Re = 35,300 to Re = 2200, where the Reynolds number is defined according to the hydraulic diameter of a rectangular slot of height H. According to the literature, just after the exit of the jet there is a zone of flow, called zone of flow establishment, containing the region of mixing fluid, at the border with the stagnant fluid, and the potential core, where velocity on the centerline maintains a value almost equal to the exit one. After this zone is present the zone of established flow or fully developed region. The goal of the paper is to show, with average PIV visualizations and measurements, that, before the zone of flow establishment is present a region of flow, never mentioned by the literature and called undisturbed region of flow, with a length, L U , which decreases with the increase of the Reynolds number. The main characteristics of the undisturbed region is the fact that the velocity profile maintains almost equal to the exit one, and can also be identified by a constant height of the average PIV visualizations, with length, L CH , or by a constant turbulence on the centerline, with length L CT . The average PIV velocity and turbulence measurements are compared to those performed with the Hot Film Anemometry (HFA) technique. The average PIV visualizations show that the region of constant height has

Experimental study of curvature effects on jet impingement heat transfer on concave surfaces

Directory of Open Access Journals (Sweden)

Ying Zhou

2017-04-01

Full Text Available Experimental study of the local and average heat transfer characteristics of a single round jet impinging on the concave surfaces was conducted in this work to gain in-depth knowledge of the curvature effects. The experiments were conducted by employing a piccolo tube with one single jet hole over a wide range of parameters: jet Reynolds number from 27000 to 130000, relative nozzle to surface distance from 3.3 to 30, and relative surface curvature from 0.005 to 0.030. Experimental results indicate that the surface curvature has opposite effects on heat transfer characteristics. On one hand, an increase of relative nozzle to surface distance (increasing jet diameter in fact enhances the average heat transfer around the surface for the same curved surface. On the other hand, the average Nusselt number decreases as relative nozzle to surface distance increases for a fixed jet diameter. Finally, experimental data-based correlations of the average Nusselt number over the curved surface were obtained with consideration of surface curvature effect. This work contributes to a better understanding of the curvature effects on heat transfer of a round jet impingement on concave surfaces, which is of high importance to the design of the aircraft anti-icing system.

Numerical and experimental study on a pulsed-dc plasma jet

Science.gov (United States)

Liu, X. Y.; Pei, X. K.; Lu, X. P.; Liu, D. W.

2014-06-01

A numerical and experimental study of plasma jet propagation in a low-temperature, atmospheric-pressure, helium jet in ambient air is presented. A self-consistent, multi-species, two-dimensional axially symmetric plasma model with detailed finite-rate chemistry of helium-air mixture composition is used to provide insights into the propagation of the plasma jet. The obtained simulation results suggest that the sheath forms near the dielectric tube inner surface and shields the plasma channel from the tube surface. The strong electric field at the edge of the dielectric field enhances the ionization in the air mixing layer; therefore, the streamer head becomes ring-shaped when the streamer runs out of the tube. The avalanche-to-streamer transition is the main mechanism of streamer advancement. Penning ionization dominates the ionization reactions and increases the electrical conductivity of the plasma channel. The simulation results are supported by experimental observations under similar discharge conditions.

Experimental study of elliptical jet from sub to supercritical conditions

Energy Technology Data Exchange (ETDEWEB)

Muthukumaran, C. K.; Vaidyanathan, Aravind, E-mail: aravind7@iist.ac.in [Department of Aerospace Engineering, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India)

2014-04-15

The jet mixing at supercritical conditions involves fluid dynamics as well as thermodynamic phenomena. All the jet mixing studies at critical conditions to the present date have focused only on axisymmetric jets. When the liquid jet is injected into supercritical environment, the thermodynamic transition could be well understood by considering one of the important fluid properties such as surface tension since it decides the existence of distinct boundary between the liquid and gaseous phase. It is well known that an elliptical liquid jet undergoes axis-switching phenomena under atmospheric conditions due to the presence of surface tension. The experimental investigations were carried out with low speed elliptical jet under supercritical condition. Investigation of the binary component system with fluoroketone jet and N{sub 2} gas as environment shows that the surface tension force dominates for a large downstream distance, indicating delayed thermodynamic transition. The increase in pressure to critical state at supercritical temperature is found to expedite the thermodynamic transition. The ligament like structures has been observed rather than droplets for supercritical pressures. However, for the single component system with fluoroketone jet and fluoroketone environment shows that the jet disintegrates into droplets as it is subjected to the chamber conditions even for the subcritical pressures and no axis switching phenomenon is observed. For a single component system, as the pressure is increased to critical state, the liquid jet exhibits gas-gas like mixing behavior and that too without exhibiting axis-switching behavior.

Visualization experimental investigation on long stripe coherent structure in small-scale rectangular channel

International Nuclear Information System (INIS)

Su Jiqiang; Sun Zhongning; Fan Guangming; Wang Shiming

2013-01-01

The long stripe coherent structure of the turbulent boundary layer in a small- scale vertical rectangular channel was observed by using hydrogen bubble flow trace visualization technique. The statistical properties of the long stripe in the experimental channel boundary layer were compared with that in the smooth flat plate boundary layer. The pitch characteristics were explained by the formation mechanism of the long stripe. It was analyzed that how the change of y + affected the distribution of the long stripe. In addition, the frequency characteristics of the long stripe were also investigated, and the correlation of the long stripe frequency in such a flow channel was obtained. (authors)

Elliptic nozzle aspect ratio effect on controlled jet propagation

Energy Technology Data Exchange (ETDEWEB)

Kumar, S M Aravindh; Rathakrishnan, Ethirajan, E-mail: aravinds@iitk.ac.in, E-mail: erath@iitk.ac.in [Department of Aerospace Engineering, Indian Institute of Technology, Kanpur (India)

2017-04-15

The present study deals with the control of a Mach 2 elliptic jet from a convergent–divergent elliptic nozzle of aspect ratio 4 using tabs at the nozzle exit. The experiments were carried out for rectangular and triangular tabs of the same blockage, placed along the major and minor axes of the nozzle exit, at different levels of nozzle expansion. The triangular tabs along the minor axis promoted superior mixing compared to the other controlled jets and caused substantial core length reduction at all the nozzle pressure ratios studied. The rectangular tabs along the minor axis caused core length reduction at all pressure ratios, but the values were minimal compared to that of triangular tabs along the minor axis. For all the test conditions, the mixing promotion caused by tabs along the major axis was inferior to that of tabs along the minor axis. The waves present in the core of controlled jets were visualized using a shadowgraph. Comparison of the present results with the results of a controlled Mach 2 elliptic jet of aspect ratio 2 (Aravindh Kumar and Sathakrishnan 2016 J. Propulsion Power 32 121–33, Aravindh Kumar and Rathakrishnan 2016 J. Aerospace Eng. at press (doi:10.1177/0954410016652921)) show that for all levels of expansion, the mixing effectiveness of triangular tabs along the minor axis of an aspect ratio 4 nozzle is better than rectangular or triangular tabs along the minor axis of an aspect ratio 2 nozzle. (paper)

Elliptic nozzle aspect ratio effect on controlled jet propagation

International Nuclear Information System (INIS)

Kumar, S M Aravindh; Rathakrishnan, Ethirajan

2017-01-01

The present study deals with the control of a Mach 2 elliptic jet from a convergent–divergent elliptic nozzle of aspect ratio 4 using tabs at the nozzle exit. The experiments were carried out for rectangular and triangular tabs of the same blockage, placed along the major and minor axes of the nozzle exit, at different levels of nozzle expansion. The triangular tabs along the minor axis promoted superior mixing compared to the other controlled jets and caused substantial core length reduction at all the nozzle pressure ratios studied. The rectangular tabs along the minor axis caused core length reduction at all pressure ratios, but the values were minimal compared to that of triangular tabs along the minor axis. For all the test conditions, the mixing promotion caused by tabs along the major axis was inferior to that of tabs along the minor axis. The waves present in the core of controlled jets were visualized using a shadowgraph. Comparison of the present results with the results of a controlled Mach 2 elliptic jet of aspect ratio 2 (Aravindh Kumar and Sathakrishnan 2016 J. Propulsion Power 32 121–33, Aravindh Kumar and Rathakrishnan 2016 J. Aerospace Eng. at press (doi:10.1177/0954410016652921)) show that for all levels of expansion, the mixing effectiveness of triangular tabs along the minor axis of an aspect ratio 4 nozzle is better than rectangular or triangular tabs along the minor axis of an aspect ratio 2 nozzle. (paper)

Experimental study for flow regime of downward air-water two-phase flow in a vertical narrow rectangular channel

Energy Technology Data Exchange (ETDEWEB)

Kim, T. H.; Yun, B. J.; Jeong, J. H. [Pusan National University, Geunjeong-gu, Busan (Korea, Republic of)

2015-05-15

Studies were mostly about flow in upward flow in medium size circular tube. Although there are great differences between upward and downward flow, studies on vertical upward flow are much more active than those on vertical downward flow in a channel. In addition, due to the increase of surface forces and friction pressure drop, the pattern of gas-liquid two-phase flow bounded to the gap of inside the rectangular channel is different from that in a tube. The downward flow in a rectangular channel is universally applicable to cool the plate type nuclear fuel in research reactor. The sub-channel of the plate type nuclear fuel is designed with a few millimeters. Downward air-water two-phase flow in vertical rectangular channel was experimentally observed. The depth, width, and length of the rectangular channel is 2.35 mm, 66.7 mm, and 780 mm, respectively. The test section consists of transparent acrylic plates confined within a stainless steel frame. The flow patterns of the downward flow in high liquid velocity appeared to be similar to those observed in previous studies with upward flow. In downward flow, the transition lines for bubbly-slug and slug-churn flow shift to left in the flow regime map constructed with abscissa of the superficial gas velocity and ordinate of the superficial liquid velocity. The flow patterns observed with downward flow at low liquid velocity are different from those with upward flow.

Numerical analysis of two experiments related to thermal fatigue

Energy Technology Data Exchange (ETDEWEB)

Bieder, Ulrich; Errante, Paolo [DEN-STMF, Commissariat a l' Energie Atomique et aux Energies Alternatives, Universite Paris-Saclay, Gif-sur-Yvette (France)

2017-06-15

Jets in cross flow are of fundamental industrial importance and play an important role in validating turbulence models. Two jet configurations related to thermal fatigue phenomena are investigated: • T-junction of circular tubes where a heated jet discharges into a cold main flow and • Rectangular jet marked by a scalar discharging into a main flow in a rectangular channel. The T-junction configuration is a classical test case for thermal fatigue phenomena. The Vattenfall T-junction experiment was already subject of an OECD/NEA benchmark. A LES modelling and calculation strategy is developed and validated on this data. The rectangular-jet configuration is important for basic physical understanding and modelling and has been analyzed experimentally at CEA. The experimental work was focused on turbulent mixing between a slightly heated rectangular jet which is injected perpendicularly into the cold main flow of a rectangular channel. These experiments are analyzed for the first time with LES. The overall results show a good agreement between the experimental data and the CFD calculation. Mean values of velocity and temperature are well captured by both RANS calculation and LES. The range of critical frequencies and their amplitudes, however, are only captured by LES.

Experimental verification of nanoparticle jet minimum quantity lubrication effectiveness in grinding

International Nuclear Information System (INIS)

Jia, Dongzhou; Li, Changhe; Zhang, Dongkun; Zhang, Yanbin; Zhang, Xiaowei

2014-01-01

In our experiment, K-P36 precision numerical control surface grinder was used for dry grinding, minimum quantity lubrication (MQL) grinding, nanoparticle jet MQL grinding, and traditional flood grinding of hardened 45 steel. A three-dimensional dynamometer was used to measure grinding force in the experiment. In this research, experiments were conducted to measure and calculate specific tangential grinding force, frictional coefficient, and specific grinding energy, thus verifying the lubrication performance of nanoparticles in surface grinding. Findings present that compared with dry grinding, the specific tangential grinding force of MQL grinding, nanoparticle jet MQL grinding, and flood grinding decreased by 45.88, 62.34, and 69.33 %, respectively. Their frictional coefficient was reduced by 11.22, 29.21, and 32.18 %, and the specific grinding energy declined by 45.89, 62.34, and 69.45 %, respectively. Nanoparticle jet MQL presented ideal lubrication effectiveness, which was attributed to the friction oil film with strong antifriction and anti-wear features formed by nanoparticles on the grinding wheel/workpiece interface. Moreover, lubricating properties of nanoparticles of the same size (50 nm) but different types were verified through experimentation. In our experiment, ZrO 2 nanoparticles, polycrystal diamond (PCD) nanoparticles, and MoS 2 nanoparticles were used in the comparison of nanoparticle jet MQL grinding. The experimental results manifest that MoS 2 nanoparticles exhibited the optimal lubricating effectiveness, followed by PCD nanoparticles. Our research also integrated the properties of different nanoparticles to analyze the lubrication mechanisms of different nanoparticles. The experiment further verified the impact of nanoparticle concentration on the effectiveness of nanoparticle jet MQL in grinding. The experimental results demonstrate that when the nanoparticle mass fraction was 6 %, the minimum specific tangential grinding force

Experimental and Numerical Investigation of Flow Properties of Supersonic Helium-Air Jets

Science.gov (United States)

Miller, Steven A. E.; Veltin, Jeremy

2010-01-01

Heated high speed subsonic and supersonic jets operating on- or off-design are a source of noise that is not yet fully understood. Helium-air mixtures can be used in the correct ratio to simulate the total temperature ratio of heated air jets and hence have the potential to provide inexpensive and reliable flow and acoustic measurements. This study presents a combination of flow measurements of helium-air high speed jets and numerical simulations of similar helium-air mixture and heated air jets. Jets issuing from axisymmetric convergent and convergent-divergent nozzles are investigated, and the results show very strong similarity with heated air jet measurements found in the literature. This demonstrates the validity of simulating heated high speed jets with helium-air in the laboratory, together with the excellent agreement obtained in the presented data between the numerical predictions and the experiments. The very close match between the numerical and experimental data also validates the frozen chemistry model used in the numerical simulation.

An experimental setup for visualizations and measurements on free hypersonic jets

Directory of Open Access Journals (Sweden)

Tordella Daniela

2012-04-01

Full Text Available The free hypersonic jets can be found in several technological applications and even in astrophysical observations. This article is mainly devoted to explain an experiment about visualizations and measurements on free hypersonic jets extending on length scales in the order of hundreds of initial diameters and traveling in a medium not necessarily made of the same gas of the jets. The experiments are performed by means of special facilities where the jet Mach numbers and the jetto-ambient density ratios can be set independently of each other, what permits the investigation of a wide parameters range in the relevant physics. The Mach number of the jets ranges from 5 to 20 and the jet-to ambient density ratio, which plays an important role in the jets morphology, can be set from 0.1 up to values exceeding 100. The present setup produces the jets by means of a fast piston system (for high Mach numbers or injection valves (for low Mach numbers, both coupled with de Laval nozzles. The visualizations and measurements are based on the electron beam technique: the jets are weakly ionized, then a fast CMOS camera captures images that are analyzed by image processing techniques. A sample of the results obtained by this experimental system is included at the end of this work.

Numerical study of the thermal and aerodynamic insulation of a cavity with a vertical downstream air jet

Energy Technology Data Exchange (ETDEWEB)

Mhiri, H.; El Golli, S. [Ecole Nationale d`Ingenieurs, Monastir (Tunisia). Lab. d`Energetique; Berthon, A.; Le Palec, G.; Bournot, P. [Technopole de Chateau-Gombert, Marseille (France)

1998-10-01

Because of its numerous industrial applications (air conditioning, thermal insulation, behavior of fires), heat transfer in rectangular cavities has made the subject of many works which concern both theoretical numerical studies and experimental investigations. This work is devoted to a numerical approach of the laminar mixed convection in a cavity which one of the boundaries is materialized by a laminar vertical downstream air jet. The purpose is to analyze the interaction of this flow with the natural movement that grows in the cavity under the combined action of boundary thermal gradients and external medium of the cavity in order to examine thermal insulation qualities of the jet. Calculations have been made with the help of the finite volume method.

Jet arrays in supersonic crossflow — An experimental study

Science.gov (United States)

Ali, Mohd Yousuf; Alvi, Farrukh

2015-12-01

Jet injection into a supersonic crossflow is a classical fluid dynamics problem with many engineering applications. Several experimental and numerical studies have been taken up to analyze the interaction of a single jet with the incoming crossflow. However, there is a dearth of the literature on the interaction of multiple jets with one another and with the crossflow. Jets in a supersonic crossflow are known to produce a three-dimensional bow-shock structure due to the blockage of the flow. Multiple jets in a streamwise linear array interact with both one another and the incoming supersonic flow. In this paper, a parametric study is carried out to analyze the effect of microjet (sub-mm diameter) injection in a Mach 1.5 supersonic crossflow using flow visualization and velocity field measurements. The variation of the microjet orifice diameter and spacing within an array is used to study the three-dimensional nature of the flow field around the jets. The strength of the microjet-generated shock, scaling of the shock wave angle with the momentum coefficient, averaged streamwise, spanwise, and cross-stream velocity fields, and microjet array trajectories are detailed in the paper. It was found that shock angles of the microjet-generated shocks scale with the momentum coefficient for the three actuator configurations tested. As the microjets issue in the crossflow, a pair of longitudinal counter-rotating vortices (CVPs) are formed. The vortex pairs remain coherent for arrays with larger spanwise spacing between the micro-orifices and exhibit significant three-dimensionality similar to that of a single jet in crossflow. As the spacing between the jets is reduced, the CVPs merge resulting in a more two-dimensional flow field. The bow shock resulting from microjet injection also becomes nearly two-dimensional as the spacing between the micro-orifices is reduced. Trajectory estimations yield that microjets in an array have similar penetration as single jets. A notional

Experimental observations of a complex, supersonic nozzle concept

Science.gov (United States)

Magstadt, Andrew; Berry, Matthew; Glauser, Mark; Ruscher, Christopher; Gogineni, Sivaram; Kiel, Barry; Skytop Turbulence Labs, Syracuse University Team; Spectral Energies, LLC. Team; Air Force Research Laboratory Team

2015-11-01

A complex nozzle concept, which fuses multiple canonical flows together, has been experimentally investigated via pressure, schlieren and PIV in the anechoic chamber at Syracuse University. Motivated by future engine designs of high-performance aircraft, the rectangular, supersonic jet under investigation has a single plane of symmetry, an additional shear layer (referred to as a wall jet) and an aft deck representative of airframe integration. Operating near a Reynolds number of 3 ×106 , the nozzle architecture creates an intricate flow field comprised of high turbulence levels, shocks, shear & boundary layers, and powerful corner vortices. Current data suggest that the wall jet, which is an order of magnitude less energetic than the core, has significant control authority over the acoustic power through some non-linear process. As sound is a direct product of turbulence, experimental and analytical efforts further explore this interesting phenomenon associated with the turbulent flow. The authors acknowledge the funding source, a SBIR Phase II project with Spectral Energies, LLC. and AFRL turbine engine branch under the direction of Dr. Barry Kiel.

Experiences with rectangular waveguide

International Nuclear Information System (INIS)

Beltran, J.; Sepulveda, J. J.; Navarro, E. A.

2000-01-01

A simple and didactic experimental arrangement is presented to show wave propagation along a structure with translational symmetry, particularly the rectangular waveguide. Parameters of this waveguide as cutoff frequency, guide wavelength and field distribution of fundamental mode can be measured. For this purpose a large paralelepipedical waveguide structure is designed and built, its dimensions can be varied in order to change its parameters. (Author) 9 refs

Rotation Effect on Jet Impingement Heat Transfer in Smooth Rectangular Channels with Film Coolant Extraction

Directory of Open Access Journals (Sweden)

James A. Parsons

2001-01-01

Full Text Available The effect of channel rotation on jet impingement cooling by arrays of circular jets in twin channels was studied. Impinging jet flows were in the direction of rotation in one channel and opposite to the direction of rotation in the other channel. The jets impinged normally on the smooth, heated target wall in each channel. The spent air exited the channels through extraction holes in each target wall, which eliminates cross flow on other jets. Jet rotation numbers and jet Reynolds numbers varied from 0.0 to 0.0028 and 5000 to 10,000, respectively. For the target walls with jet flow in the direction of rotation (or opposite to the direction of rotation, as rotation number increases heat transfer decreases up to 25% (or 15% as compared to corresponding results for non-rotating conditions. This is due to the changes in flow distribution and rotation induced Coriolis and centrifugal forces.

Computational and experimental study of the effect of mass transfer on liquid jet break-up

Science.gov (United States)

Schetz, J. A.; Situ, M.

1983-06-01

A computational method has been developed to predict the effect of mass transfer on liquid jet break-up in coaxial, low velocity gas streams. Two conditions, both with and without the effect of mass transfer on the jet break-up, are calculated, and compared with experimental results and the classical linear theory. Methanol and water were used as the injectants. The numerical solution can predict the instantaneous shape of the jet surface and the break-up time, and it is very close to the experimental results. The numerical solutions and the experimental results both indicate that the wave number of the maximum instability is about 6.9, higher than 4.51 which was predicted by Rayleigh's linear theory. The experimental results and numerical solution show that the growth of the amplitude of the trough is faster than the growth of the amplitude of the crest, especially for a rapidly vaporizing jet. The numerical solutions show that for the small rates of evaporation, the effect of the mass transfer on the interface has a stabilizing effect near the wave number for maximum instability. Inversely, it has a destabilizing effect far from the wave number for maximum instability. For rapid evaporation, the effect of the mass transfer always has a destabilizing effect and decreases the break-up time of the jet.

Experimental and Numerical Study of Twin Underexpanded Impinging Jets

Institute of Scientific and Technical Information of China (English)

Minoru Yaga; Minoru Okano; Masumi Tamashiro; Kenyu Oyakawa

2003-01-01

In this paper, the dual underexpanded impinging jets are experimentally and numerically studied. The experiments were performed by measuring the unsteady and averaged wall static pressures and by visualizing density fields using schlieren method. Numerical calculations were also conducted by solving unsteady three dimensional compressible Navier-Stokes equations with Baldwin-Lomax turbulence model. The main parameters for the dual jets are the non-dimensional distance between the two nozzle centers H/D covering 1.5, 2.0, the nozzle to plate separation L/D 2.0, 3.0,4.0 and 5.0 and the pressure ratio defined by Po/Pb 1.0～6.0, where D is the diameter of each nozzle exit, Po the stagnation pressure and Pb the back pressure. It is found that the agreement between the experiments and the calculations is good. The fountain flow at the middle of the two jets is observed both in the experiments and the calculation. According to FFT analysis of the experiments for the twin jets,relatively low frequency (up to 5 kHz) is dominant for H/D =1.5, L/D =2.0 and pressure ratio Po/Pb =3.0 and 5.0,which is confirmed by the experiments.

Jet-Surface Interaction - High Aspect Ratio Nozzle Test: Test Summary

Science.gov (United States)

Brown, Clifford A.

2016-01-01

The Jet-Surface Interaction High Aspect Ratio Nozzle Test was conducted in the Aero-Acoustic Propulsion Laboratory at the NASA Glenn Research Center in the fall of 2015. There were four primary goals specified for this test: (1) extend the current noise database for rectangular nozzles to higher aspect ratios, (2) verify data previously acquired at small-scale with data from a larger model, (3) acquired jet-surface interaction noise data suitable for creating verifying empirical noise models and (4) investigate the effect of nozzle septa on the jet-mixing and jet-surface interaction noise. These slides give a summary of the test with representative results for each goal.

Experimental and kinetic modeling study of 3-methylheptane in a jet-stirred reactor

KAUST Repository

Karsenty, Florent

2012-08-16

Improving the combustion of conventional and alternative fuels in practical applications requires the fundamental understanding of large hydrocarbon combustion chemistry. The focus of the present study is on a high-molecular-weight branched alkane, namely, 3-methylheptane, oxidized in a jet-stirred reactor. This fuel, along with 2-methylheptane, 2,5-dimethylhexane, and n-octane, are candidate surrogate components for conventional diesel fuels derived from petroleum, synthetic Fischer-Tropsch diesel and jet fuels derived from coal, natural gas, and/or biomass, and renewable diesel and jet fuels derived from the thermochemical treatment of bioderived fats and oils. This study presents new experimental results along with a low- and high-temperature chemical kinetic model for the oxidation of 3-methylheptane. The proposed model is validated against these new experimental data from a jet-stirred reactor operated at 10 atm, over the temperature range of 530-1220 K, and for equivalence ratios of 0.5, 1, and 2. Significant effort is placed on the understanding of the effects of methyl substitution on important combustion properties, such as fuel reactivity and species formation. It was found that 3-methylheptane reacts more slowly than 2-methylheptane at both low and high temperatures in the jet-stirred reactor. © 2012 American Chemical Society.

An experimental and numerical study into turbulent condensing steam jets in air

Energy Technology Data Exchange (ETDEWEB)

Oerlemans, S. [Faculty of Applied Physics Eindhoven, Univ. of Technology Eindhoven (Netherlands); Badie, R. [Philips Research Laboratories Eindhoven (Netherlands); Dongen, M.E.H. van [Faculty of Applied Physics, Eindhoven Univ. of Technology (Netherlands)

2001-07-01

Temperatures, velocities, and droplet sizes are measured in turbulent condensing steam jets produced by a facial sauna, for varying nozzle diameters and varying initial velocities (Re=3,600-9,200). The release of latent heat due to droplet condensation causes the temperature in the two-phase jet to be significantly higher than in a single-phase jet. At some distance from the nozzle, droplets reach a maximum size and start to evaporate again, which results in a change in sign of latent heat release. The distance of maximum size is determined from droplet size measurements. The experimental results are compared with semi-analytical expressions and with a fully coupled numerical model of the turbulent condensing steam jet. The increase in centreline temperature due to droplet condensation is successfully predicted. (orig.)

Experimental investigation of the mixing processes in a Jet-in-Crossflow arrangement; Experimentelle Untersuchung von Vermischungsvorgaengen in einer Jet-in-Crossflow-Anordnung

Energy Technology Data Exchange (ETDEWEB)

Cardenas, C.; Suntz, R.; Bockhorn, H. [Karlsruhe Univ. (T.H.) (Germany). Inst. fuer Technische Chemie und Polymerchemie

2008-07-15

The Jet-in-Crossflow flow arrangement is a geometrically simple flow configuration in which an open jet is injected vertically into a constant crossflow and the two flows are thus mixed with one another. This flow arrangement is frequently encountered in industrial applications and also in nature. Examples can be found in industrial burners, RQL gas turbines, T-mixers, smoke plumes from stacks and volcanoes, and the jets emitted by aviation gas-turbines and by rockets. The subject of this publication is quantitative experimental determination of the Reynolds flows and stresses in a Jet-in-Crossflow arrangement. The variables stated reflect turbulence-induced elevated mass transfer in a turbulent vis-a-vis a laminar flow and are thus intimately linked to mixing processes. Their experimental determination is of great importance for the generation and validation of numerical turbulence models. Simultaneous use of two laser-diagnosis methods, 2D LIF (Two-dimensional Laser-induced Fluorescence) and PIV (Particle Image Velocimetry) makes it possible to establish 2D concentration and velocity fields simultaneously and determine the variables mentioned directly. (orig.)

Studies of turbulent round jets through experimentation, simulation, and modeling

Science.gov (United States)

Keedy, Ryan

analysis computationally taxing. A Probability Density Function (PDF) model for the concentration of scalars, as well as for the droplet number in different size bins, is developed. The growth of droplets as they evolve along the jet, for different downstream and radial positions, compared favorably with experimental measurements in the literature. We utilized a graphical processing unit with the PDF method to more efficiently compute the statistics of the droplet diameter in the non-uniform supersaturation field.

An Experimental Study of Turbulent Nonpremixed Jet Flames in Crossflow Under Low-Gravity Conditions

Science.gov (United States)

Boxx, Isaac G.; Idicheria, Cherian A.; Clemens, Noel T.

2002-11-01

We will present results of a study of turbulent nonpremixed jet flames in crossflow under normal and low gravity conditions. This enables us to experimentally separate the competing influences of initial jet-to-crossflow momentum ratio and buoyancy effects on the flame structure. The low gravity conditions (10-30 milli-g) are achieved by dropping a self-contained jet flame rig in the University of Texas 1.25-second drop tower facility. This rig uses a small blow-through wind tunnel to create the crossflow. The jet flames issue from an orifice that is flush with the wall. High-speed CCD imaging of jet flame luminosity is the primary diagnostic. We present results for hydrocarbon jet flames with initial jet-to-crossflow momentum ratios of 10-20. Results such as flame trajectory, flame length, large scale structure and flame tip dynamics will be presented.

A new metamaterial-based wideband rectangular invisibility cloak

Science.gov (United States)

Islam, S. S.; Hasan, M. M.; Faruque, M. R. I.

2018-02-01

A new metamaterial-based wideband electromagnetic rectangular cloak is being introduced in this study. The metamaterial unit cell shows sharp transmittances in the C- and X-bands and displays wideband negative effective permittivity region there. The metamaterial unit cell was then applied in designing a rectangular-shaped electromagnetic cloak. The scattering reduction technique was adopted for the cloaking operation. The cloak operates in the certain portion of C-and X-bands that covers more than 4 GHz bandwidth region. The experimental results were provided as well for the metamaterial and the cloak.

Experimental study of the turbulent flow around a single wall-mounted cube exposed to a cross-flow and an impinging jet

International Nuclear Information System (INIS)

Masip, Yunesky; Rivas, Alejandro; Larraona, Gorka S.; Anton, Raúl; Ramos, Juan Carlos; Moshfegh, Bahram

2012-01-01

Highlights: ► We measured the instantaneous flow velocity using 2D-Particle Image Velocimetry. ► Recirculation bubbles, vortices, detachment and reattachment zones are showed. ► The influence of the Re H and Re j /Re H was studied. ► The Re j /Re H determines the effects produced around the component. - Abstract: The air flow around a cubic obstacle mounted on one wall of a rectangular channel was studied experimentally. The obstacle represents an electronic component and the channel the space between two parallel printed circuit boards (PCBs). The flow was produced by the combination of a channel stream and a jet which issued from a circular nozzle placed at the wall opposite from where the component is mounted. With this aim, a test rig was designed and built to carry out experiments with both the above mentioned configurations and other cooling arrangements. Planar Particle Image Velocimetry (PIV) was employed to measure the instantaneous flow velocity on several planes covering the space around the component. The mean velocity and the Reynolds stresses were obtained from averaging the instantaneous velocity, and the mean flow showed a complex pattern with different features such as recirculation bubbles, vortices, detachment and reattachment zones. The influence of two parameters, namely the channel Reynolds number and the jet-to-channel Reynolds number ratio, on these flow features was studied considering nine cases that combined three values of the channel Reynolds number (3410, 5752 and 8880) and three values of the ratio (0.5, 1.0 and 1.5). The results show that the Reynolds number ratio determines the drag produced on the jet and the deflection from its geometric axis due to the channel stream. In all the cases corresponding to the lowest value of the ratio, the jet was dragged and did not impact the component. This fact accounts for the non-existence of the Upper Horseshoe Vortex and changes in the flow characteristics at the region over the

Experimental investigation on influence of porous material properties on drying process by a hot air jet

International Nuclear Information System (INIS)

Di Marco, P; Filippeschi, S

2012-01-01

The drying process of porous media is a subject of scientific interest, and different mathematical approaches can be found in the literature. A previous paper by the same authors showed that the celebrated Martin correlation for hot air jet heat and mass transfer yields different degrees of accuracy (from 15% to 65%, increasing at high values of input power) if tested on different fabrics, the remaining conditions being the same. In this paper the fabric drying has been experimentally investigated more in depth. A dedicated experimental apparatus for hot jet drying was assembled and operated, in which a hot jet impinges perpendicularly onto a wet fabric. A calibrated orifice was adopted to measure the jet flow rate, with an accuracy better than 3%. The drying power was determined by continuously weighing with a precision scale a moistened patch exposed to the drying jet. The effect of the time of the exposure and the initial amount of water has been evaluated for each sample. During the hot jet exposure, the temperature distribution over the wet patch has been observed by an infrared thermo-camera. A mathematical model of water transport inside and outside the fabric was developed, in order to evidence the governing transport resistances. The theoretical predictions have been compared with the experimental results, and showed the necessity to modify correlations and models accounting for fabric properties.

EXPERIMENTAL AND NUMERICAL STUDY OF THE BEHAVIOUR AND FLOW KINEMATICS OF THE FORMATION OF GREEN WATER ON A RECTANGULAR STRUCTURE

Directory of Open Access Journals (Sweden)

Gang Nam Lee

2016-09-01

Full Text Available In this study, the behaviour of green water impacting on a fixed rectangular structure is studied, and the flow kinematics is investigated with a series of experiments and computational fluid dynamic simulations. The experiments are conducted in a two-dimensional wave flume with the structure under regular wave conditions that are scaled down by the ratio of 1:125 from the BW Pioneer FPSO (Floating production storage and offloading operated in the Gulf of Mexico. The mean values of the horizontal and vertical velocity profiles are provided for the water and bubbly flow induced by the interaction between the rectangular structure and regular waves. CFD simulations are also performed by STAR-CCM+ using the volume-of-fluid (VOF method based on the finite-volume method (FVM and all of CFD results are compared with the experimental data.

Experimental verification of the thermodynamic properties for a jet-A fuel

Science.gov (United States)

Graciasalcedo, Carmen M.; Brabbs, Theodore A.; Mcbride, Bonnie J.

1988-01-01

Thermodynamic properties for a Jet-A fuel were determined by Shell Development Company in 1970 under a contract for NASA Lewis Research Center. The polynomial fit necessary to include Jet-A fuel (liquid and gaseous phases) in the library of thermodynamic properties of the NASA Lewis Chemical Equilibrium Program is calculated. To verify the thermodynamic data, the temperatures of mixtures of liquid Jet-A injected into a hot nitrogen stream were experimentally measured and compared to those calculated by the program. Iso-octane, a fuel for which the thermodynamic properties are well known, was used as a standard to calibrate the apparatus. The measured temperatures for the iso-octane/nitrogen mixtures reproduced the calculated temperatures except for a small loss due to the non-adiabatic behavior of the apparatus. The measurements for Jet-A were corrected for this heat loss and showed excellent agreement with the calculated temperatures. These experiments show that this process can be adequately described by the thermodynamic properties fitted for the Chemical Equilibrium Program.

Experimental study on spray characteristics of alternate jet fuels using Phase Doppler Anemometry

Science.gov (United States)

Kannaiyan, Kumaran; Sadr, Reza

2013-11-01

Gas-to-Liquid (GTL) fuels have gained global attention due to their cleaner combustion characteristics. The chemical and physical properties of GTL jet fuels are different from conventional jet fuels owing to the difference in their production methodology. It is important to study the spray characteristics of GTL jet fuels as the change of physical properties can affect atomization, mixing, evaporation and combustion process, ultimately affecting emission process. In this work, spray characteristics of two GTL synthetic jet fuels are studied using a pressure-swirl nozzle at different injection pressures and atmospheric ambient condition. Phase Doppler Anemometry (PDA) measurements of droplet size and velocity are compared with those of regular Jet A-1 fuel at several axial and radial locations downstream of the nozzle exit. Experimental results show that although the GTL fuels have different physical properties such as viscosity, density, and surface tension, among each other the resultant change in the spray characteristics is insignificant. Furthermore, the presented results show that GTL fuel spray characteristics exhibit close similarity to those of Jet A-1 fuel. Funded by Qatar Science and Technology Park.

A two-component NZRI metamaterial based rectangular cloak

Directory of Open Access Journals (Sweden)

Sikder Sunbeam Islam

2015-10-01

Full Text Available A new two-component, near zero refractive index (NZRI metamaterial is presented for electromagnetic rectangular cloaking operation in the microwave range. In the basic design a pi-shaped, metamaterial was developed and its characteristics were investigated for the two major axes (x and z-axis wave propagation through the material. For the z-axis wave propagation, it shows more than 2 GHz bandwidth and for the x-axis wave propagation; it exhibits more than 1 GHz bandwidth of NZRI property. The metamaterial was then utilized in designing a rectangular cloak where a metal cylinder was cloaked perfectly in the C-band area of microwave regime. The experimental result was provided for the metamaterial and the cloak and these results were compared with the simulated results. This is a novel and promising design for its two-component NZRI characteristics and rectangular cloaking operation in the electromagnetic paradigm.

Mechanism of jet-flutter: self-induced oscillation of an upward plane jet impinging on a free surface

International Nuclear Information System (INIS)

Madarame, Haruki; Iida, Masao

1998-01-01

An upward plane jet impinging on the free surface of a shallow rectangular tank oscillates without any external periodic force. The movement of the impinging point leaves additional fluid mass on the surface behind the point, which does not balance the momentum supplied by the jet. The imbalance generates propagating waves, and a surface level gap appears there. The level gap is flattened not by the waves but by the vertical motion of water columns. The imbalance causes lateral displacement of jet, which in turn causes the imbalance, forming a positive feedback loop. The above model explains well why the frequency corresponds to that of water column oscillation in a partitioned tank with the same water depth, and the oscillation region has a wide range above a certain velocity limit determined by the water depth. (author)

Analysis of high aspect ratio jet flap wings of arbitrary geometry.

Science.gov (United States)

Lissaman, P. B. S.

1973-01-01

Paper presents a design technique for rapidly computing lift, induced drag, and spanwise loading of unswept jet flap wings of arbitrary thickness, chord, twist, blowing, and jet angle, including discontinuities. Linear theory is used, extending Spence's method for elliptically loaded jet flap wings. Curves for uniformly blown rectangular wings are presented for direct performance estimation. Arbitrary planforms require a simple computer program. Method of reducing wing to equivalent stretched, twisted, unblown planform for hand calculation is also given. Results correlate with limited existing data, and show lifting line theory is reasonable down to aspect ratios of 5.

Evanescently Coupled Rectangular Microresonators in Silicon-on-Insulator with High Q-Values: Experimental Characterization

Directory of Open Access Journals (Sweden)

Manuel Mendez-Astudillo

2017-04-01

Full Text Available We report on evanescently coupled rectangular microresonators with dimensions up to 20 × 10 μm2 in silicon-on-insulator in an add-drop filter configuration. The influence of the geometrical parameters of the device was experimentally characterized and a high Q value of 13,000 was demonstrated as well as the multimode optical resonance characteristics in the drop port. We also show a 95% energy transfer between ports when the device is operated in TM-polarization and determine the full symmetry of the device by using an eight-port configuration, allowing the drop waveguide to be placed on any of its sides, providing a way to filter and route optical signals. We used the FDTD method to analyze the device and e-beam lithography and dry etching techniques for fabrication.

Finite element fatigue analysis of rectangular clutch spring of automatic slack adjuster

Science.gov (United States)

Xu, Chen-jie; Luo, Zai; Hu, Xiao-feng; Jiang, Wen-song

2015-02-01

The failure of rectangular clutch spring of automatic slack adjuster directly affects the work of automatic slack adjuster. We establish the structural mechanics model of automatic slack adjuster rectangular clutch spring based on its working principle and mechanical structure. In addition, we upload such structural mechanics model to ANSYS Workbench FEA system to predict the fatigue life of rectangular clutch spring. FEA results show that the fatigue life of rectangular clutch spring is 2.0403×105 cycle under the effect of braking loads. In the meantime, fatigue tests of 20 automatic slack adjusters are carried out on the fatigue test bench to verify the conclusion of the structural mechanics model. The experimental results show that the mean fatigue life of rectangular clutch spring is 1.9101×105, which meets the results based on the finite element analysis using ANSYS Workbench FEA system.

An experimental study on downstream of the transition of the chemically reacting liquid round free jet

International Nuclear Information System (INIS)

Hong, S.D.; Sugii, Y.; Okamoto, K.; Madarame, H.

2002-01-01

An experimental study was conducted on the chemically reacting liquid round free jet, Laser Induced Fluorescence (LIF) technique was adopted to evaluate the diffusion width of the jet into liquid streams. In the fluid engineering, it is very important to evaluate the characteristics of reacting jet for the safety of the nuclear reactor. In this study, the jet profile of downstream region far away from the transition point was evaluated, providing comparisons between reacting and non-reacting jet case. The concentration of the jet solution was varied from 0.01 mol/L to 0.5 mol/L in reacting cases. In the downstream far away from the transition point, the jet profiles between reacting cases and non-reacting cases were visualized quite different. It was concluded that the chemical reaction affects the momentum diffusion of the jet in the downstream region. (author)

Numerical and experimental study of pulse-jet cleaning in fabric filters

DEFF Research Database (Denmark)

O. Andersen, B.; Nielsen, N. F.; Walther, J. H.

2016-01-01

Pulse-jet cleaning and understanding of the complex physics are essential when designing fabric filters used for air pollution control. Today, low-pressure cleaning is of particular interest due to demand for reduced compressed air consumption. Pulse-jet cleaned fabric filters have been studied......-pressure fabric filters (2 bar) is studied using a full three-dimensional (3D) CFD model. Experimental results obtained in a pilot-scale test filter with 28 bags, in length of 10 m and in general full-scale dimensions of the cleaning system are used to verify the reliability of the present CFD model....... The validated CFD model reveals the strong compressible effects, a highly transient behaviour, the formation of compressible vortex rings and the shock cell phenomenon within the overexpanded supersonic jet. The cleaning nozzles and venturi design aid or oppose the pulse-pressure within the bags, and this plays...

Study on the Effect of the Impact Location and the Type of Hammer Tip on the Frequency Response Function (FRF) in Experimental Modal Analysis of Rectangular Plates

Science.gov (United States)

Mali, K. D.; Singru, P. M.

2018-03-01

In this work effect of the impact location and the type of hammer tip on the frequency response function (FRF) is studied. Experimental modal analysis of rectangular plates is carried out for this purpose by using impact hammer, accelerometer and fast Fourier transform (FFT) analyzer. It is observed that the impulse hammer hit location has, no effect on the eigenfrequency, yet a difference in amplitude of the eigenfrequencies is obtained. The effect of the hammer tip on the pulse and the force spectrum is studied for three types of tips metal, plastic and rubber. A solid rectangular plate was excited by using these tips one by one in three different tests. It is observed that for present experimental set up plastic tip excites the useful frequency range.

Experimental and numerical investigation of liquid jet impingement on superhydrophobic and hydrophobic convex surfaces

International Nuclear Information System (INIS)

Kibar, Ali

2017-01-01

Experiments and numerical simulations were carried out to examine the vertical impingement a round liquid jet on the edges of horizontal convex surfaces that were either superhydrophobic or hydrophobic. The experiments examine the effects on the flow behaviour of curvature, wettability, inertia of the jet, and the impingement rate. Three copper pipes with outer diameters of 15, 22, and 35 mm were investigated. The pipes were wrapped with a piece of a Brassica oleracea leaf or a smooth Teflon sheet, which have apparent contact angles of 160° and 113°. The Reynolds number ranged from 1000 to 4500, and the impingement rates of the liquid jets were varied. Numerical results show good agreement with the experimental results for explaining flow and provide detailed information about the impingement on the surfaces. The liquid jet reflected off the superhydrophobic surfaces for all conditions. However, the jet reflected or deflected off the hydrophobic surface, depending on the inertia of the jet, the curvature of the surface, and the impingement rate. The results suggest that pressure is not the main reason for the bending of the jet around the curved hydrophobic surface. (paper)

Experimental and numerical investigation of liquid jet impingement on superhydrophobic and hydrophobic convex surfaces

Energy Technology Data Exchange (ETDEWEB)

Kibar, Ali, E-mail: alikibar@kocaeli.edu.tr [Department of Mechanical and Material Technologies, Kocaeli University, Arslanbey Campus, 41285, Kocaeli (Turkey)

2017-02-15

Experiments and numerical simulations were carried out to examine the vertical impingement a round liquid jet on the edges of horizontal convex surfaces that were either superhydrophobic or hydrophobic. The experiments examine the effects on the flow behaviour of curvature, wettability, inertia of the jet, and the impingement rate. Three copper pipes with outer diameters of 15, 22, and 35 mm were investigated. The pipes were wrapped with a piece of a Brassica oleracea leaf or a smooth Teflon sheet, which have apparent contact angles of 160° and 113°. The Reynolds number ranged from 1000 to 4500, and the impingement rates of the liquid jets were varied. Numerical results show good agreement with the experimental results for explaining flow and provide detailed information about the impingement on the surfaces. The liquid jet reflected off the superhydrophobic surfaces for all conditions. However, the jet reflected or deflected off the hydrophobic surface, depending on the inertia of the jet, the curvature of the surface, and the impingement rate. The results suggest that pressure is not the main reason for the bending of the jet around the curved hydrophobic surface. (paper)

In vitro blood flow in a rectangular PDMS microchannel: experimental observations using a confocal micro-PIV system.

Science.gov (United States)

Lima, Rui; Wada, Shigeo; Tanaka, Shuji; Takeda, Motohiro; Ishikawa, Takuji; Tsubota, Ken-ichi; Imai, Yohsuke; Yamaguchi, Takami

2008-04-01

Progress in microfabricated technologies has attracted the attention of researchers in several areas, including microcirculation. Microfluidic devices are expected to provide powerful tools not only to better understand the biophysical behavior of blood flow in microvessels, but also for disease diagnosis. Such microfluidic devices for biomedical applications must be compatible with state-of-the-art flow measuring techniques, such as confocal microparticle image velocimetry (PIV). This confocal system has the ability to not only quantify flow patterns inside microchannels with high spatial and temporal resolution, but can also be used to obtain velocity measurements for several optically sectioned images along the depth of the microchannel. In this study, we investigated the ability to obtain velocity measurements using physiological saline (PS) and in vitro blood in a rectangular polydimethysiloxane (PDMS) microchannel (300 microm wide, 45 microm deep) using a confocal micro-PIV system. Applying this combination, measurements of trace particles seeded in the flow were performed for both fluids at a constant flow rate (Re = 0.02). Velocity profiles were acquired by successive measurements at different depth positions to obtain three-dimensional (3-D) information on the behavior of both fluid flows. Generally, the velocity profiles were found to be markedly blunt in the central region, mainly due to the low aspect ratio (h/w = 0.15) of the rectangular microchannel. Predictions using a theoretical model for the rectangular microchannel corresponded quite well with the experimental micro-PIV results for the PS fluid. However, for the in vitro blood with 20% hematocrit, small fluctuations were found in the velocity profiles. The present study clearly shows that confocal micro-PIV can be effectively integrated with a PDMS microchannel and used to obtain blood velocity profiles along the full depth of the microchannel because of its unique 3-D optical sectioning ability

An experimental study of the heat transfer performance of a rectangular two-phase natural circulation loop

International Nuclear Information System (INIS)

Chen, K.S.; Chen, Y.Y.; Tsai, S.T.

1990-01-01

An experimental study is presented for the heat transfer performance of a rectangular, two-phase, natural-circulation loop with water-steam as the working fluid. Local temperature measurements of the core fluid and the wall were made, and the overall heat transfer coefficients of the evaporator, the condenser, and the loop system were obtained and correlated in terms of the fluid properties, heat flux conditions, and the liquid charge level. An overheat phenomenon at very low charge level was also observed. Result of a preliminary analysis shows that if the liquid charge level is below the fractional volume of the connecting tube between the condenser and the evaporator, an overheat phenomenon will occur

Convective heat transfer around vertical jet fires: An experimental study

Energy Technology Data Exchange (ETDEWEB)

Kozanoglu, Bulent, E-mail: bulentu.kozanoglu@udlap.mx [Universidad de las Americas, Puebla (Mexico); Zarate, Luis [Universidad Popular Autonoma del Estado de Puebla (Mexico); Gomez-Mares, Mercedes [Universita di Bologna (Italy); Casal, Joaquim [Universitat Politecnica de Catalunya (Spain)

2011-12-15

Highlights: Black-Right-Pointing-Pointer Experiments were carried out to analyze convection around a vertical jet fire. Black-Right-Pointing-Pointer Convection heat transfer is enhanced increasing the flame length. Black-Right-Pointing-Pointer Nusselt number grows with higher values of Rayleigh and Reynolds numbers. Black-Right-Pointing-Pointer In subsonic flames, Nusselt number increases with Froude number. Black-Right-Pointing-Pointer Convection and radiation are equally important in causing a domino effect. - Abstract: The convection heat transfer phenomenon in vertical jet fires was experimentally analyzed. In these experiments, turbulent propane flames were generated in subsonic as well as sonic regimes. The experimental data demonstrated that the rate of convection heat transfer increases by increasing the length of the flame. Assuming the solid flame model, the convection heat transfer coefficient was calculated. Two equations in terms of adimensional numbers were developed. It was found out that the Nusselt number attains greater values for higher values of the Rayleigh and Reynolds numbers. On the other hand, the Froude number was analyzed only for the subsonic flames where the Nusselt number grows by this number and the diameter of the orifice.

Experimental study on breakup and fragmentation behavior of molten material jet in complicated structure of BWR lower plenum

International Nuclear Information System (INIS)

Saito, Ryusuke; Abe, Yutaka; Yoshida, Hiroyuki

2014-01-01

To estimate the state of reactor pressure vessel of Fukushima Daiichi nuclear power plant, it is important to clarify the breakup and fragmentation of molten material jet in the lower plenum of boiling water reactor (BWR) by a numerical simulation. To clarify the effects of complicated structures on the jet behavior experimentally and validate the simulation code, we conduct the visualized experiments simulating the severe accident in the BWR lower plenum. In this study, jet breakup, fragmentation and surrounding velocity profiles of the jet were observed by the backlight method and the particle image velocimetry (PIV) method. From experimental results using the backlight method, it was clarified that jet tip velocity depends on the conditions whether complicated structures exist or not and also clarified that the structures prevent the core of the jet from expanding. From measurements by the PIV method, the surrounding velocity profiles of the jet in the complicated structures were relatively larger than the condition without structure. Finally, fragment diameters measured in the present study well agree with the theory suggested by Kataoka and Ishii by changing the coefficient term. Thus, it was suggested that the fragmentation mechanism was mainly controlled by shearing stress. (author)

Numerical analysis of high-speed Lithium jet flow under vacuum conditions

International Nuclear Information System (INIS)

Gordeev, Sergej; Groeschel, Friedrich; Stieglitz, Robert

2016-01-01

The EVEDA Li test loop (ELTL) [1] is aimed at validating the hydraulic stability of the Lithium (Li) target at a velocity up to 20 m/s at vacuum (≈10 −3 Pa). The ELTL has been designed to demonstrate the feasibility of the major components providing a neutron production liquid Li target for IFMIF. The rectangular shaped Li jet (cross-section 25 mm × 100 mm) necessitates for heat removal flow velocities of 15–20 m/s along a concave shaped back wall (curvature radius 250 mm) towards the outlet pipe, where the Li jet is subjected to vacuum before it finally enters the collecting quench tank. During the validation experiments within the ELTL acoustic waves within the target outlet pipe have been recorded, indicating potential cavitation processes in the jet impinging region, which may cause premature failures. In order to identify potential cavitation phenomena in correlation with the free jet flow in the outlet pipe a numerical study has been performed. The comparison measured and simulated acoustic emissions exhibits that experimentally deduced cavitation area coincides with the location of the jet wall impingement. The simulations further reveal that a part of the fluid after striking the wall even flows opposite to the gravity vector. This reversed flow is inherently unstable and characterized by waves at first growing and then bursting into droplets. The intense generation of small droplets increases significantly the Li free surface area and lead to a production of Li vapour, which is captured by the jet flow and reintroduced in the main flow. As the static pressure is recovered downstream due to jet impact, the vapour bubbles collapse and hence cavitation likely occurs.

Numerical analysis of high-speed Lithium jet flow under vacuum conditions

Energy Technology Data Exchange (ETDEWEB)

Gordeev, Sergej, E-mail: sergej.gordeev@kit.edu; Groeschel, Friedrich; Stieglitz, Robert

2016-11-01

The EVEDA Li test loop (ELTL) [1] is aimed at validating the hydraulic stability of the Lithium (Li) target at a velocity up to 20 m/s at vacuum (≈10{sup −3} Pa). The ELTL has been designed to demonstrate the feasibility of the major components providing a neutron production liquid Li target for IFMIF. The rectangular shaped Li jet (cross-section 25 mm × 100 mm) necessitates for heat removal flow velocities of 15–20 m/s along a concave shaped back wall (curvature radius 250 mm) towards the outlet pipe, where the Li jet is subjected to vacuum before it finally enters the collecting quench tank. During the validation experiments within the ELTL acoustic waves within the target outlet pipe have been recorded, indicating potential cavitation processes in the jet impinging region, which may cause premature failures. In order to identify potential cavitation phenomena in correlation with the free jet flow in the outlet pipe a numerical study has been performed. The comparison measured and simulated acoustic emissions exhibits that experimentally deduced cavitation area coincides with the location of the jet wall impingement. The simulations further reveal that a part of the fluid after striking the wall even flows opposite to the gravity vector. This reversed flow is inherently unstable and characterized by waves at first growing and then bursting into droplets. The intense generation of small droplets increases significantly the Li free surface area and lead to a production of Li vapour, which is captured by the jet flow and reintroduced in the main flow. As the static pressure is recovered downstream due to jet impact, the vapour bubbles collapse and hence cavitation likely occurs.

Optical implementation of (3, 3, 2) regular rectangular CC-Banyan optical network

Science.gov (United States)

Yang, Junbo; Su, Xianyu

2007-07-01

CC-Banyan network plays an important role in the optical interconnection network. Based on previous reports of (2, 2, 3) the CC-Banyan network, another rectangular-Banyan network, i.e. (3, 3, 2) rectangular CC-Banyan network, has been discussed. First, according to its construction principle, the topological graph and the routing rule of (3, 3, 2) rectangular CC-Banyan network have been proposed. Then, the optically experimental setup of (3, 3, 2) rectangular CC-Banyan network has been designed and achieved. Each stage of node switch consists of phase spatial light modulator (PSLM) and polarizing beam-splitter (PBS), and fiber has been used to perform connection between adjacent stages. PBS features that s-component (perpendicular to the incident plane) of the incident light beam is reflected, and p-component (parallel to the incident plane) passes through it. According to switching logic, under the control of external electrical signals, PSLM functions to control routing paths of the signal beams, i.e. the polarization of each optical signal is rotated or not rotated 90° by a programmable PSLM. Finally, the discussion and analysis show that the experimental setup designed here can realize many functions such as optical signal switch and permutation. It has advantages of large number of input/output-ports, compact in structure, and low energy loss. Hence, the experimental setup can be used in optical communication and optical information processing.

Analysis of jet flames and unignited jets from unintended releases of hydrogen

Energy Technology Data Exchange (ETDEWEB)

Houf, W.G.; Evans, G.H.; Schefer, R.W. [Sandia National Laboratories, Livermore, CA 94551-0969 (United States)

2009-07-15

A combined experimental and modeling program is being carried out at Sandia National Laboratories to characterize and predict the behavior of unintended hydrogen releases. In the case where the hydrogen leak remains unignited, knowledge of the concentration field and flammability envelope is an issue of importance in determining consequence distances for the safe use of hydrogen. In the case where a high-pressure leak of hydrogen is ignited, a classic turbulent jet flame forms. Knowledge of the flame length and thermal radiation heat flux distribution is important to safety. Depending on the effective diameter of the leak and the tank source pressure, free jet flames can be extensive in length and pose significant radiation and impingement hazard, resulting in consequence distances that are unacceptably large. One possible mitigation strategy to potentially reduce the exposure to jet flames is to incorporate barriers around hydrogen storage equipment. The reasoning is that walls will reduce the extent of unacceptable consequences due to jet releases resulting from accidents involving high-pressure equipment. While reducing the jet extent, the walls may introduce other hazards if not configured properly. The goal of this work is to provide guidance on configuration and placement of these walls to minimize overall hazards using a quantitative risk assessment approach. The program includes detailed CFD calculations of jet flames and unignited jets to predict how hydrogen leaks and jet flames interact with barriers, complemented by an experimental validation program that considers the interaction of jet flames and unignited jets with barriers. As a first step in this work on barrier release interaction the Sandia CFD model has been validated by computing the concentration decay of unignited turbulent free jets and comparing the results with the classic concentration decay laws for turbulent free jets taken from experimental data. Computations for turbulent hydrogen

Optimal design for rectangular isolated footings using the real soil pressure

Directory of Open Access Journals (Sweden)

Arnulfo Luévanos Rojas

2017-05-01

Full Text Available The standard design method (classical method for reinforced concrete rectangular footings is: First, a dimension is proposed and should comply with the allowable stresses; subsequently, the effective depth is obtained from the maximum moment and is checked against the bending shear and the punching shear until, it complies with these conditions and, then, steel reinforcement is obtained, but it is not guarantee that the minimum cost will be obtained. This paper shows an optimal design for reinforced concrete rectangular footings using the new model. A numerical experimentation is presented to show the model capability to estimate the minimum cost design of the materials used for a rectangular footing that supports an axial load and moments in two directions in accordance to the building code requirements for structural concrete and commentary (ACI 318-13. Also, a comparison is made between the optimal design and current design for rectangular footings. The solutions show that the optimal design is more economical and more precise with respect to the current design, because standard design is done by trial and error. Then, the optimal design should be used to obtain the minimum cost design for reinforced concrete rectangular footings.

Experimental Investigation on the Material Removal of the Ultrasonic Vibration Assisted Abrasive Water Jet Machining Ceramics

Directory of Open Access Journals (Sweden)

Tao Wang

2017-01-01

Full Text Available The ultrasonic vibration activated in the abrasive water jet nozzle is used to enhance the capability of the abrasive water jet machinery. The experiment devices of the ultrasonic vibration assisted abrasive water jet are established; they are composed of the ultrasonic vibration producing device, the abrasive supplying device, the abrasive water jet nozzle, the water jet intensifier pump, and so on. And the effect of process parameters such as the vibration amplitude, the system working pressure, the stand-off, and the abrasive diameter on the ceramics material removal is studied. The experimental result indicates that the depth and the volume removal are increased when the ultrasonic vibration is added on abrasive water jet. With the increase of vibration amplitude, the depth and the volume of material removal are also increased. The other parameters of the ultrasonic vibration assisted abrasive water jet also have an important role in the improvement of ceramic material erosion efficiency.

Experimental investigation of edge localised modes in JET

International Nuclear Information System (INIS)

Lindholm Colton, A.

1993-08-01

Edge Localised Modes (ELMs) in the JET tokamak have been studied experimentally, using density profile and fluctuation data from a multichannel reflectometer and temperature profile data from an ECE heterodyne radiometer. The following topics have been investigated: The radial extent and localisation of the density and temperature profile perturbations caused by the ELMs. Fluctuations in the density and magnetic field in connection with the ELMs. The correlation between the repetition frequency of the L-H transition ELMs, and the plasma edge temperature and density. Trajectories in n-T space prior to ELMs later in the H-mode. (au) (39 refs.)

High resolution 3D gas-jet characterization

International Nuclear Information System (INIS)

Landgraf, Bjoern; Kaluza, Malte C.; Spielmann, Christian; Schnell, Michael; Saevert, Alexander

2011-01-01

We present a tomographic characterization of gas jets employed for high-intensity laser-plasma interaction experiments where the shape can be non-symmetrically. With a Mach-Zehnder interferometer we measured the phase shift for different directions through the neutral density distribution of the gas jet. From the recorded interferograms it is possible to retrieve 3-dimensional neutral density distributions by tomographic reconstruction based on the filtered back projections. We report on criteria for the smallest number of recorded interferograms as well as a comparison with the widely used phase retrieval based on an Abel inversion. As an example for the performance of our approach, we present the characterization of nozzles with rectangular openings or gas jets with shock waves. With our setup we obtained a spatial resolution of less than 60 μm for an Argon density as low as 2 x 10 17 cm -3 .

An experimental study of the supersonic, dual, coaxial jets impinging on an inclined flat plate

International Nuclear Information System (INIS)

Kim, Jung Bae; Lee, Jun Hee; Woo, Sun Hoon; Kim, Heuy Dong

2002-01-01

The impinging supersonic jets have been applied for rocket launching system, thrust control, gas turbine blade cooling, etc. Recently the supersonic, dual, coaxial jets are being extensively used in many diverse fields of industrial processes since they lead to more improved performance, compared with the conventional supersonic jets impinging on an object. In the present study, experimentation is carried out to investigate the supersonic, dual, coaxial jets impinging on an inclined flat plate. A convergent-divergent nozzle with a design Mach number of 2.0 and annular sonic nozzle are used to make the dual, coaxial jet flows. The angle of the impinging flat plate is varied from 30 .deg. to 60 .deg. and the distance between the dual coaxial nozzle and flat plate is also varied. Detailed pressures on the impinging plate are measured to analyze the flow fields, which are also visualized using Schlieren optical method

First experimental results with the Current Limit Avoidance System at the JET tokamak

Energy Technology Data Exchange (ETDEWEB)

De Tommasi, G. [Associazione EURATOM-ENEA-CREATE, Università di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); Galeani, S. [Dipartimento di Informatica, Sistemi e Produzione, Università di Roma, Tor Vergata, Rome (Italy); Jachmich, S. [Association EURATOM-Belgian State, Koninklijke Militaire School - Ecole Royale Militaire, B-1000 Brussels (Belgium); Joffrin, E. [IRFM-CEA, Centre de Cadarache, 13108 Saint-paul-lez-Durance (France); Lennholm, M. [EFDA Close Support Unit, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); European Commission, B-1049 Brussels (Belgium); Lomas, P.J. [Euratom-CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Neto, A.C. [Associazione EURATOM-IST, Instituto de Plasmas e Fusao Nuclear, IST, 1049-001 Lisboa (Portugal); Maviglia, F. [Associazione EURATOM-ENEA-CREATE, Via Claudio 21, 80125 Napoli (Italy); McCullen, P. [Euratom-CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Pironti, A. [Associazione EURATOM-ENEA-CREATE, Università di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); Rimini, F.G. [Euratom-CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Sips, A.C.C. [European Commission, B-1049 Brussels (Belgium); Varano, G.; Vitelli, R. [Dipartimento di Informatica, Sistemi e Produzione, Università di Roma, Tor Vergata, Rome (Italy); Zaccarian, L. [CNRS, LAAS, 7 Avenue du Colonel Roche, F-31400 Toulouse (France); Universitè de Toulouse, LAAS, F-31400 Toulouse (France)

2013-06-15

The Current Limit Avoidance System (CLA) has been recently deployed at the JET tokamak to avoid current saturations in the poloidal field (PF) coils when the eXtreme Shape Controller is used to control the plasma shape. In order to cope with the current saturation limits, the CLA exploits the redundancy of the PF coils system to automatically obtain almost the same plasma shape using a different combination of currents in the PF coils. In the presence of disturbances it tries to avoid the current saturations by relaxing the constraints on the plasma shape control. The CLA system has been successfully implemented on the JET tokamak and fully commissioned in 2011. This paper presents the first experimental results achieved in 2011–2012 during the restart and the ITER-like wall campaigns at JET.

FDTD Analysis of U-Slot Rectangular Patch Antenna

Science.gov (United States)

Luk, K. M.; Tong, K. F.; Shum, S. M.; Lee, K. F.; Lee, R. Q.

1997-01-01

The U-slot rectangular patch antenna (Figure I) has been found experimentally to provide impedance and gain bandwidths of about 300 without the need of stacked or coplanar parasitic elements [1,2]. In this paper, simulation results of the U-slot patch using FDTD analysis are presented. Comparison with measured results are given.

Experimental study of rapidity gaps in gluon jets

CERN Document Server

Gary, J W

2003-01-01

Gluon jets are selected from hadronic Z/sup 0/ decay events produced in e/sup +/e/sup -/ annihilations, collected with the OPAL detector at LEP. A subsample of these jets is identified which exhibit a large gap in the rapidity distribution of particles within the jet. These jets are observed to demonstrate a high degree of sensitivity to the presence of color reconnection, i.e. higher order QCD processes affecting the underlying color structure. We test two QCD Monte Carlo programs which implement color reconnection: one in the Ariadne Monte Carlo and the other by Rathsman in the Pythia Monte Carlo. We find these models can describe our gluon jet measurements only if very large values are used for the cutoff parameters which serve to terminate the parton showers, and conclude that color reconnection as implemented in these models is disfavored. Further, we use our data on gluon jets with a rapidity gap to search for glueball-like objects in the leading part of those jets. We do not find any clear evidence for...

Simulation of buoyancy-induced turbulent flow from a hot horizontal jet

KAUST Repository

El-Amin, Mohamed

2014-02-01

Experimental visualizations and numerical simulations of a horizontal hot water jet entering cold water into a rectangular storage tank are described. Three different temperature differences and their corresponding Reynolds numbers are considered. Both experimental visualization and numerical computations are carried out for the same flow and thermal conditions. The realizable k - ε model is used for modeling the turbulent flow while the buoyancy is modeled using the Boussinesq approximation. Polynomial approximations of the water properties are used to compare with the Boussinesq approximation. Numerical solutions are obtained for unsteady flow while pressure, velocity, temperature and turbulence distributions inside the water tank as well as the Froude number are analyzed. The experimental visualizations are performed at intervals of five seconds for all different cases. The simulated results are compared with the visualized results, and both of them show the stratification phenomena and buoyancy force effects due to temperature difference and density variation. After certain times, depending on the case condition, the flow tends to reach a steady state. © 2014 Publishing House for Journal of Hydrodynamics.

Modeling on bubbly to churn flow pattern transition in narrow rectangular channel

International Nuclear Information System (INIS)

Wang Yanlin; Chen Bingde; Huang Yanping; Wang Junfeng

2012-01-01

A theoretical model based on some reasonable concepts was developed to predict the bubbly flow to churn flow pattern transition in vertical narrow rectangular channel under flow boiling condition. The maximum size of ideal bubble in narrow rectangular channel was calculated based on previous literature. The thermal hydraulics boundary condition of bubbly to churn flow pattern transition was exported from Helmholtz and maximum size of ideal bubble. The theoretical model was validated by existent experimental data. (authors)

Metamaterial Embedded Wearable Rectangular Microstrip Patch Antenna

Directory of Open Access Journals (Sweden)

J. G. Joshi

2012-01-01

Full Text Available This paper presents an indigenous low-cost metamaterial embedded wearable rectangular microstrip patch antenna using polyester substrate for IEEE 802.11a WLAN applications. The proposed antenna resonates at 5.10 GHz with a bandwidth and gain of 97 MHz and 4.92 dBi, respectively. The electrical size of this antenna is 0.254λ×0.5λ. The slots are cut in rectangular patch to reduce the bending effect. This leads to mismatch the impedance at WLAN frequency band; hence, a metamaterial square SRR is embedded inside the slot. A prototype antenna has been fabricated and tested, and the measured results are presented in this paper. The simulated and measured results of the proposed antenna are found to be in good agreement. The bending effect on the performance of this antenna is experimentally verified.

Rectangular cartograms: the game

NARCIS (Netherlands)

Berg, de M.T.; Nijnatten, van F.S.B.; Speckmann, B.; Verbeek, K.A.B.

2009-01-01

Raisz [3] introduced rectangular cartograms in 1934 as a way of visualizing spatial information, such as population or economic strength, of a set of regions like countries or states. Rectangular cartograms represent geographic regions by rectangles; the positioning and adjacencies of the rectangles

Jet substructure using semi-inclusive jet functions in SCET

International Nuclear Information System (INIS)

Kang, Zhong-Bo; Ringer, Felix; Vitev, Ivan

2016-01-01

We propose a new method to evaluate jet substructure observables in inclusive jet measurements, based upon semi-inclusive jet functions in the framework of Soft Collinear Effective Theory (SCET). As a first example, we consider the jet fragmentation function, where a hadron h is identified inside a fully reconstructed jet. We introduce a new semi-inclusive fragmenting jet function G_i"h(z=ω_J/ω,z_h=ω_h/ω_J,ω_J,R,μ), which depends on the jet radius R and the large light-cone momenta of the parton ‘i’ initiating the jet (ω), the jet (ω_J), and the hadron h (ω_h). The jet fragmentation function can then be expressed as a semi-inclusive observable, in the spirit of actual experimental measurements, rather than as an exclusive one. We demonstrate the consistency of the effective field theory treatment and standard perturbative QCD calculations of this observable at next-to-leading order (NLO). The renormalization group (RG) equation for the semi-inclusive fragmenting jet function G_i"h(z,z_h,ω_J,R,μ) are also derived and shown to follow exactly the usual timelike DGLAP evolution equations for fragmentation functions. The newly obtained RG equations can be used to perform the resummation of single logarithms of the jet radius parameter R up to next-to-leading logarithmic (NLL_R) accuracy. In combination with the fixed NLO calculation, we obtain NLO+NLL_R results for the hadron distribution inside the jet. We present numerical results for pp→(jet h)X in the new framework, and find excellent agreement with existing LHC experimental data.

Analytical and experimental study of the acoustics and the flow field characteristics of cavitating self-resonating water jets

Energy Technology Data Exchange (ETDEWEB)

Chahine, G.L.; Genoux, P.F.; Johnson, V.E. Jr.; Frederick, G.S.

1984-09-01

Waterjet nozzles (STRATOJETS) have been developed which achieve passive structuring of cavitating submerged jets into discrete ring vortices, and which possess cavitation incipient numbers six times higher than obtained with conventional cavitating jet nozzles. In this study we developed analytical and numerical techniques and conducted experimental work to gain an understanding of the basic phenomena involved. The achievements are: (1) a thorough analysis of the acoustic dynamics of the feed pipe to the nozzle; (2) a theory for bubble ring growth and collapse; (3) a numerical model for jet simulation; (4) an experimental observation and analysis of candidate second-generation low-sigma STRATOJETS. From this study we can conclude that intensification of bubble ring collapse and design of highly resonant feed tubes can lead to improved drilling rates. The models here described are excellent tools to analyze the various parameters needed for STRATOJET optimizations. Further analysis is needed to introduce such important factors as viscosity, nozzle-jet interaction, and ring-target interaction, and to develop the jet simulation model to describe the important fine details of the flow field at the nozzle exit.

Experimental studies of collisional plasma shocks and plasma interpenetration via merging supersonic plasma jets

Science.gov (United States)

Hsu, S. C.; Moser, A. L.; Merritt, E. C.; Adams, C. S.

2015-11-01

Over the past 4 years on the Plasma Liner Experiment (PLX) at LANL, we have studied obliquely and head-on-merging supersonic plasma jets of an argon/impurity or hydrogen/impurity mixture. The jets are formed/launched by pulsed-power-driven railguns. In successive experimental campaigns, we characterized the (a) evolution of plasma parameters of a single plasma jet as it propagated up to ~ 1 m away from the railgun nozzle, (b) density profiles and 2D morphology of the stagnation layer and oblique shocks that formed between obliquely merging jets, and (c) collisionless interpenetration transitioning to collisional stagnation between head-on-merging jets. Key plasma diagnostics included a fast-framing CCD camera, an 8-chord visible interferometer, a survey spectrometer, and a photodiode array. This talk summarizes the primary results mentioned above, and highlights analyses of inferred post-shock temperatures based on observations of density gradients that we attribute to shock-layer thickness. We also briefly describe more recent PLX experiments on Rayleigh-Taylor-instability evolution with magnetic and viscous effects, and potential future collisionless shock experiments enabled by low-impurity, higher-velocity plasma jets formed by contoured-gap coaxial guns. Supported by DOE Fusion Energy Sciences and LANL LDRD.

Experimental evaluation on natural convection heat transfer of microencapsulated phase change materials slurry in a rectangular heat storage tank

International Nuclear Information System (INIS)

Zhang Yanlai; Rao Zhonghao; Wang Shuangfeng; Zhang Zhao; Li Xiuping

2012-01-01

Highlights: ► It gives heat transfer characteristics in a rectangular heat storage tank as the basic unit for reservoir of thermal storage. ► Onset of natural convection gets easier for the MPCMS with a higher mass concentration. ► It enhances the heat transfer ability of natural convection for the MPCMS. ► Obtained the relationship between Ra and Nu of the MPCMS. - Abstract: The main purpose of this experiment is to evaluate natural convection heat transfer characteristics of microencapsulated PCM (phase change material) slurry (MPCMS) during phase change process in a rectangular heat storage tank heated from the bottom and cooled at the top. The microencapsulated PCM is several material compositions of n-paraffin waxes (mainly nonadecane) as the core materials, outside a layer of a melamine resin wrapped. In the present study, its slurry is used mixing with water. And the specific heat capacity with latent heat shows a peak value at the temperature of about T = 31 °C. We investigate the influences of the phase change process of the MPCMS on natural convection heat transfer. The experimental results indicate that phase change process of the MPCMS promote natural convection heat transfer. The local maximum heat transfer enhancement occurs at approximately T H = 34 °C corresponding to the heated plate temperature. With high mass concentration C m , the onset of natural convection gets easier for the MPCMS. The temperature gradient is larger near top plate and bottom plate of a rectangular heat storage tank. Heat transfer coefficient increases with the phase change of the PCM. And it summarizes that the phase change process of the PCM promote the occurrence of natural convection.

Exploring neural networks to improve b-jet tagging with the ALICE detector

CERN Multimedia

CERN. Geneva

2017-01-01

Highly energetic jets are sensitive probes for the kinematics and the topology of nuclear collisions. Jets are collimated sprays of charged and neutral particles, which are produced in the fragmentation of hard scattered partons in an early stage of the collision. Heavy-quark jets, originating from beauty or charm quarks (b- and c-jets), are particularly good probes to shed light on the characteristics of the hot medium which is formed in heavy-ion collisions and to understand the parton energy loss in the medium. There exist several algorithms to tag b-jets. One approach is to identify b-jets by reconstructing displaced secondary vertices and applying rectangular cuts on their topology. Machine learning is a promising tool to perform better in such a classification task on similar input features. In particular, deep learning methods might be able to catch features from low-level parameters which are not exploited by the classical cut-based method. In this talk, first simulation results of a neural network b...

Experimental study on boiling heat transfer to an impinging jet on a hot block

International Nuclear Information System (INIS)

Kamata, Choko

1997-01-01

Previous studies on boiling heat transfer by impinging jets are mainly concerned with the impinging point by using small heat transfer surfaces of about 20 mm. An experimental study of the boiling heat transfer to an impinging water jet on a massive hot block is made. The upward heating surface is made of copper. Its diameter and nozzle diameter are 80 mm and 2.2 mm, respectively. The velocity of the impinging jet was varied from 0.6 to 2.1 m/s. Saturated water normally impinged on the heating surface, flowed radially, and subsequently dispersed into the atmosphere. The present study clarifies that heat transfer characteristics vary with the temperature of heat transfer surface, and also with the distance from the impinging point. (author)

CPV cells cooling system based on submerged jet impingement: CFD modeling and experimental validation

Science.gov (United States)

Montorfano, Davide; Gaetano, Antonio; Barbato, Maurizio C.; Ambrosetti, Gianluca; Pedretti, Andrea

2014-09-01

Concentrating photovoltaic (CPV) cells offer higher efficiencies with regard to the PV ones and allow to strongly reduce the overall solar cell area. However, to operate correctly and exploit their advantages, their temperature has to be kept low and as uniform as possible and the cooling circuit pressure drops need to be limited. In this work an impingement water jet cooling system specifically designed for an industrial HCPV receiver is studied. Through the literature and by means of accurate computational fluid dynamics (CFD) simulations, the nozzle to plate distance, the number of jets and the nozzle pitch, i.e. the distance between adjacent jets, were optimized. Afterwards, extensive experimental tests were performed to validate pressure drops and cooling power simulation results.

Investigating the Feedback Path in a Jet-Surface Resonant Interaction

Science.gov (United States)

Zaman, Khairul; Fagan, Amy; Bridges, James; Brown, Cliff

2015-01-01

A resonant interaction between an 8:1 aspect ratio rectangular jet and flat-plates, placed parallel to the jet, is addressed in this study. For certain relative locations of the plates, the resonance takes place with accompanying audible tones. Even when the tone is not audible the sound pressure level spectra is often marked by conspicuous peaks. The frequencies of the spectral peaks, as functions of the streamwise length of the plate and its relative location to the jet as well as the jet Mach number, are explored in an effort of understand the flow mechanism. It is demonstrated that the tones are not due to a simple feedback between the plates trailing edge and the nozzle exit; the leading edge also comes into play in determining the frequency. An acoustic feedback path, involving diffraction from the leading edge, appears to explain the frequencies of some of the spectral peaks.

Study of microburst-induced wind flow and its effects on cube-shaped buildings using numerical and experimental simulations of an impinging jet

Science.gov (United States)

Sengupta, Anindya

Microbursts are a major cause of concern for structures both on ground as well as those in air, namely aircrafts. The velocity profile of a microburst is completely different compared to natural boundary-layer wind profiles. The current research is directed to simulation of microburst phenomenon using an impinging jet model. This research reports the first 3D numerical simulation of microbursts and its effects on buildings. Broadly the major accomplishments of the current research can be focused in three major directions. In the first case, extensive research on velocity profiles of the wall jet that is formed after jet impingement has been conducted experimentally. The main motivation was to develop empirical equations for boundary layer growth based on experimental data, using hot-wire, PIV and pressure rake. Numerical simulations were carried out with different turbulence models so as to find the best turbulence model to simulate this kind of flow. In the second case, both mean and peak loads on building models under static microburst wind loadings were studied, using both experimental as well as numerical techniques. Parametric study by varying the height of jet impingement, jet exit velocities and size of building models was conducted. It was found that the large eddy simulation (LES) produced results in excellent agreement with the experimental data. The flow field around the building model was obtained using PIV and comparisons were made with the LES results. Thirdly, and the most important part of this research work was to simulate a translating microburst and study the loads on buildings using a moving impinging jet. Numerical simulation was validated with the experimental data for one jet translation speed. LES results again matched the experimental data for translating microburst loads on building, with reference to the drag and lift coefficients. The peak loads predicted by LES were within experimental limits. Effects of increased jet translation speeds

Experimentally obtained values of electric field of an atmospheric pressure plasma jet impinging on a dielectric surface

NARCIS (Netherlands)

Sobota, A.; Guaitella, O.; Garcia-Caurel, E.

2013-01-01

We report on experimentally obtained values of the electric field magnitude on a dielectric surface induced by an impinging atmospheric pressure plasma jet. The plasma plume was striking the dielectric surface at an angle of 45¿, at 5mm from the surface measured at the axis of the jet. The results

Jet substructure using semi-inclusive jet functions in SCET

Energy Technology Data Exchange (ETDEWEB)

Kang, Zhong-Bo [Theoretical Division, Los Alamos National Laboratory,Los Alamos, NM 87545 (United States); Department of Physics and Astronomy, University of California,Los Angeles, CA 90095 (United States); Ringer, Felix; Vitev, Ivan [Theoretical Division, Los Alamos National Laboratory,Los Alamos, NM 87545 (United States)

2016-11-25

We propose a new method to evaluate jet substructure observables in inclusive jet measurements, based upon semi-inclusive jet functions in the framework of Soft Collinear Effective Theory (SCET). As a first example, we consider the jet fragmentation function, where a hadron h is identified inside a fully reconstructed jet. We introduce a new semi-inclusive fragmenting jet function G{sub i}{sup h}(z=ω{sub J}/ω,z{sub h}=ω{sub h}/ω{sub J},ω{sub J},R,μ), which depends on the jet radius R and the large light-cone momenta of the parton ‘i’ initiating the jet (ω), the jet (ω{sub J}), and the hadron h (ω{sub h}). The jet fragmentation function can then be expressed as a semi-inclusive observable, in the spirit of actual experimental measurements, rather than as an exclusive one. We demonstrate the consistency of the effective field theory treatment and standard perturbative QCD calculations of this observable at next-to-leading order (NLO). The renormalization group (RG) equation for the semi-inclusive fragmenting jet function G{sub i}{sup h}(z,z{sub h},ω{sub J},R,μ) are also derived and shown to follow exactly the usual timelike DGLAP evolution equations for fragmentation functions. The newly obtained RG equations can be used to perform the resummation of single logarithms of the jet radius parameter R up to next-to-leading logarithmic (NLL{sub R}) accuracy. In combination with the fixed NLO calculation, we obtain NLO+NLL{sub R} results for the hadron distribution inside the jet. We present numerical results for pp→(jet h)X in the new framework, and find excellent agreement with existing LHC experimental data.

Experimental study for thermal striping phenomena of parallel triple-jet. Effects of the difference between hot jets and cold jet in discharged temperature and velocity on convective mixing

International Nuclear Information System (INIS)

Kimura, Nobuyuki; Tokuhiro, A.; Miyakoshi, Hiroyuki

1996-10-01

Elucidation on thermal hydraulic behavior of Thermal Striping is of importance for a reactor safety, which is arisen form exit temperature difference of fuel subassemblies. Since its temperature fluctuation may cause thermal cycle fatigue on upper internal structure (UIS). A series of experiments was performed using the Thermal Striping water test facility in order to investigate the mixing phenomena on three vertical jets with exit velocity and temperature differences. The parameters were the velocity and temperature of the jets at discharge nozzles. The local velocities were measured by Ultrasound Velocity Profile (UVP) monitor and Laser Doppler Anemometry (LDA), and temperature distributions were measured by thermocouples. This report mainly examined the experimental results of temperature measurements. There is a typical region where the gradient of the temperature variation in the triple-jet: that is the Convective Mixing region. This region is independent of the discharged temperature difference, and spreads with larger velocity difference among the jets. For isovelocity discharge conditions, non-dimensional temperature fields are almost independent of discharged temperature differences within Convective Mixing region. Consequently, the effect of temperature difference is negligible compared to that of velocity difference on the flow field. There are remarkable frequencies of 2-5Hz in temperature fluctuation due to a oscillation of the central jet (cold jet) for this condition. While, for non-isovelocity discharge condition, there are no remarkable frequencies. Hence, it is clear that there is the region where a large thermal fatigue is imposed by Thermal Striping against structures of Fast Reactor. It is suggested that the structures have to be placed outside of Convective Mixing region. Also, it is considered that typical frequencies in temperature fluctuation are controlled by giving a discharge velocity difference between cold and hot jets. (J.P.N.)

Internal wave emission from baroclinic jets: experimental results

Science.gov (United States)

Borcia, Ion D.; Rodda, Costanza; Harlander, Uwe

2016-04-01

Large-scale balanced flows can spontaneously radiate meso-scale inertia-gravity waves (IGWs) and are thus in fact unbalanced. While flow-dependent parameterizations for the radiation of IGWs from orographic and convective sources do exist, the situation is less developed for spontaneously emitted IGWs. Observations identify increased IGW activity in the vicinity of jet exit regions. A direct interpretation of those based on geostrophic adjustment might be tempting. However, directly applying this concept to the parameterization of spontaneous imbalance is difficult since the dynamics itself is continuously re-establishing an unbalanced flow which then sheds imbalances by GW radiation. Examining spontaneous IGW emission in the atmosphere and validating parameterization schemes confronts the scientist with particular challenges. Due to its extreme complexity, GW emission will always be embedded in the interaction of a multitude of interdependent processes, many of which are hardly detectable from analysis or campaign data. The benefits of repeated and more detailed measurements, while representing the only source of information about the real atmosphere, are limited by the non-repeatability of an atmospheric situation. The same event never occurs twice. This argues for complementary laboratory experiments, which can provide a more focused dialogue between experiment and theory. Indeed, life cycles are also examined in rotating-annulus laboratory experiments. Thus, these experiments might form a useful empirical benchmark for theoretical and modeling work that is also independent of any sort of subgrid model. In addition, the more direct correspondence between experimental and model data and the data reproducibility makes lab experiments a powerful testbed for parameterizations. Here we show first results from a small rotating annulus experiments and we will further present our new experimental facility to study wave emission from jets and fronts.

Experimental Studies for the characterization of the mixing processes in negative buoyant jets

Directory of Open Access Journals (Sweden)

Querzoli G.

2013-04-01

Full Text Available A negatively buoyant jet (NBJ corresponds to the physical phenomenon that develops when a fluid is discharged upwards into a lighter environment or downwards into a heavier receptor fluid. In a NBJ the flow is initially driven mostly by the momentum, so it basically behaves as a simple jet released withthe same angle, while far from the outlet the buoyancy prevails, bending the jet axis down and making it similar to a plume. The coexistence in the same phenomenon of both the characteristics of simple jets and plumes makes the NBJs a phenomenon still not entirely explained but, considering also the numerous practical applications, very interesting to study. Here some of the experimental results are presented. The laboratory experiment were obtained on a model simulating a typical sea discharge of brine from desalination plants: a pipe laid down on the sea bottom, with orifices on its lateral wall, releasing brine (heavier than the sea water with a certain angle to the horizontal, in order to increase the jet path before sinking to the seafloor. A non-intrusive image analysis technique, namely Feature Tracking Velocimetry, is applied to measure velocity fields, with the aim at understanding the influence of some non-dimensional parameters driving the phenomenon (e.g. Reynolds number, release angle on the structure of the NBJ and of the turbulence.

Experimental and modeling analysis of fast ionization wave discharge propagation in a rectangular geometry

International Nuclear Information System (INIS)

Takashima, Keisuke; Adamovich, Igor V.; Xiong Zhongmin; Kushner, Mark J.; Starikovskaia, Svetlana; Czarnetzki, Uwe; Luggenhoelscher, Dirk

2011-01-01

Fast ionization wave (FIW), nanosecond pulse discharge propagation in nitrogen and helium in a rectangular geometry channel/waveguide is studied experimentally using calibrated capacitive probe measurements. The repetitive nanosecond pulse discharge in the channel was generated using a custom designed pulsed plasma generator (peak voltage 10-40 kV, pulse duration 30-100 ns, and voltage rise time ∼1 kV/ns), generating a sequence of alternating polarity high-voltage pulses at a pulse repetition rate of 20 Hz. Both negative polarity and positive polarity ionization waves have been studied. Ionization wave speed, as well as time-resolved potential distributions and axial electric field distributions in the propagating discharge are inferred from the capacitive probe data. ICCD images show that at the present conditions the FIW discharge in helium is diffuse and volume-filling, while in nitrogen the discharge propagates along the walls of the channel. FIW discharge propagation has been analyzed numerically using quasi-one-dimensional and two-dimensional kinetic models in a hydrodynamic (drift-diffusion), local ionization approximation. The wave speed and the electric field distribution in the wave front predicted by the model are in good agreement with the experimental results. A self-similar analytic solution of the fast ionization wave propagation equations has also been obtained. The analytic model of the FIW discharge predicts key ionization wave parameters, such as wave speed, peak electric field in the front, potential difference across the wave, and electron density as functions of the waveform on the high voltage electrode, in good agreement with the numerical calculations and the experimental results.

Advanced Supersonic Nozzle Concepts: Experimental Flow Visualization Results Paired With LES

Science.gov (United States)

Berry, Matthew; Magstadt, Andrew; Stack, Cory; Gaitonde, Datta; Glauser, Mark; Syracuse University Team; The Ohio State University Team

2015-11-01

Advanced supersonic nozzle concepts are currently under investigation, utilizing multiple bypass streams and airframe integration to bolster performance and efficiency. This work focuses on the parametric study of a supersonic, multi-stream jet with aft deck. The single plane of symmetry, rectangular nozzle, displays very complex and unique flow characteristics. Flow visualization techniques in the form of PIV and schlieren capture flow features at various deck lengths and Mach numbers. LES is compared to the experimental results to both validate the computational model and identify limitations of the simulation. By comparing experimental results to LES, this study will help create a foundation of knowledge for advanced nozzle designs in future aircraft. SBIR Phase II with Spectral Energies, LLC under direction of Barry Kiel.

Modeling on bubbly to churn flow pattern transition for vertical upward flows in narrow rectangular channel

International Nuclear Information System (INIS)

Wang Yanlin; Chen Bingde; Huang Yanping; Wang Junfeng

2011-01-01

A theoretical model was developed to predict the bubbly to churn flow pattern transition for vertical upward flows in narrow rectangular channel. The model was developed based on the imbalance theory of Helmholtz and some reasonable assumptions. The maximum ideal bubble in narrow rectangular channel and the thermal hydraulics boundary condition leading to bubbly flow to churn flow pattern transition was calculated. The model was validated by experimental data from previous researches. Comparison between predicted result and experimental result shows a reasonable good agreement. (author)

Test for Jet Flow Induced by Steam Jet Condensation Using the GIRLS Facility

International Nuclear Information System (INIS)

Kim, Yeon Sik; Yoon, Y. J.; Song, C. H.

2007-03-01

To investigate the characteristics of the turbulent jet induced by steam jet condensation in a water tank through a single-hole sparger an experimental investigation was performed using the GIRLS facility. The experiments were conducted with respect to two cases, e.g. horizontal and vertical upward injections. For the measurements, pitot tube and thermocouples were used for turbulent flow velocity and temperatures, respectively. Overall flow shapes of the turbulent jet by the steam jet condensation are similar to those of axially symmetric turbulent jet flows. The angular coefficients of turbulent rays are quantitatively comparable between the traditional turbulent jet flows and the turbulent jet flows induced by the steam jet condensation in this work. Although the turbulent flows were induced by the horizontally injected steam jet condensation, general theory of turbulent jets was found to be applicable to the turbulent flows of this work. But for the vertically upward injection case, experimental data were quite deviated from the theoretical ones, which is considered due to the buoyancy effect

Analysis of experimental characteristics of multistage steam-jet electors of steam turbines

Science.gov (United States)

Aronson, K. E.; Ryabchikov, A. Yu.; Brodov, Yu. M.; Brezgin, D. V.; Zhelonkin, N. V.; Murmanskii, I. B.

2017-02-01

A series of questions for specification of physical gas dynamics model in flow range of steam-jet unit and ejector computation methodology, as well as functioning peculiarities of intercoolers, was formulated based on analysis of experimental characteristics of multistage team-jet steam turbines. It was established that coefficient defining position of critical cross-section of injected flow depends on characteristics of the "sound tube" zone. Speed of injected flow within this tube may exceed that of sound, and pressure jumps in work-steam decrease at the same time. Characteristics of the "sound tube" define optimal axial sizes of the ejector. According to measurement results, the part of steam condensing in the first-stage coolant constitutes 70-80% of steam amount supplied into coolant and is almost independent of air content in steam. Coolant efficiency depends on steam pressure defined by operation of steam-jet unit of ejector of the next stage after coolant of steam-jet stage, temperature, and condensing water flow. As a rule, steam entering content of steam-air mixture supplied to coolant is overheated with respect to saturation temperature of steam in the mixture. This should be taken into account during coolant computation. Long-term operation causes changes in roughness of walls of the ejector's mixing chamber. The influence of change of wall roughness on ejector characteristic is similar to the influence of reverse pressure of the steam-jet stage. Until some roughness value, injection coefficient of the ejector stage operating in superlimiting regime hardly changed. After reaching critical roughness, the ejector switches to prelimiting operating regime.

Study on critical heat flux based on wavelet transform in rectangular narrow channels

International Nuclear Information System (INIS)

Zhou Tao; Ju Zhongyun; Zhang Lei; Li Jingjing; Sheng Cheng; Xiao Zejun

2014-01-01

Critical heat flux is very important for nuclear reactor safety, and observing temperature rise rate is a feasible method. Through using the wavelet transform to analyze the CHF temperature rise curves in rectangular narrow channels, it can remove relative weaker interference and effectively judge CHF. Rectangular narrow channel can strengthen heat transfer and reduce CHF, whose characteristics are proved by, temperature rise curves analyzed by wavelet transform. Respectively applying Daubechies function and Haar function is for guarantee the accuracy of the wavelet analysis, and Daubechies function is more accurate than Haar function in the detail signal processing from results. While the wavelet analysis and experimental results are compared and found in good agreement with the experimental results. (authors)

Experimental study of elliptical jet from supercritical to subcritical conditions using planar laser induced fluorescence

Energy Technology Data Exchange (ETDEWEB)

Muthukumaran, C. K.; Vaidyanathan, Aravind, E-mail: aravind7@iist.ac.in [Department of Aerospace Engineering, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India)

2015-03-15

The study of fluid jet dynamics at supercritical conditions involves strong coupling between fluid dynamic and thermodynamic phenomena. Beyond the critical point, the liquid-vapor coexistence ceases to exist, and the fluid exists as a single phase known as supercritical fluid with its properties that are entirely different from liquids and gases. At the critical point, the liquids do not possess surface tension and latent heat of evaporation. Around the critical point, the fluid undergoes large changes in density and possesses thermodynamic anomaly like enhancement in thermal conductivity and specific heat. In the present work, the transition of the supercritical and near-critical elliptical jet into subcritical as well as supercritical environment is investigated experimentally with nitrogen and helium as the surrounding environment. Under atmospheric condition, a liquid jet injected from the elliptical orifice exhibits axis switching phenomena. As the injection temperature increases, the axis switching length also increases. Beyond the critical temperature, the axis switching is not observed. The investigation also revealed that pressure plays a major role in determining the thermodynamic transition of the elliptical jet only for the case of supercritical jet injected into subcritical chamber conditions. At larger pressures, the supercritical jet undergoes disintegration and formation of droplets in the subcritical environment is observed. However, for supercritical jet injection into supercritical environment, the gas-gas like mixing behavior is observed.

Experimental study of elliptical jet from supercritical to subcritical conditions using planar laser induced fluorescence

International Nuclear Information System (INIS)

Muthukumaran, C. K.; Vaidyanathan, Aravind

2015-01-01

The study of fluid jet dynamics at supercritical conditions involves strong coupling between fluid dynamic and thermodynamic phenomena. Beyond the critical point, the liquid-vapor coexistence ceases to exist, and the fluid exists as a single phase known as supercritical fluid with its properties that are entirely different from liquids and gases. At the critical point, the liquids do not possess surface tension and latent heat of evaporation. Around the critical point, the fluid undergoes large changes in density and possesses thermodynamic anomaly like enhancement in thermal conductivity and specific heat. In the present work, the transition of the supercritical and near-critical elliptical jet into subcritical as well as supercritical environment is investigated experimentally with nitrogen and helium as the surrounding environment. Under atmospheric condition, a liquid jet injected from the elliptical orifice exhibits axis switching phenomena. As the injection temperature increases, the axis switching length also increases. Beyond the critical temperature, the axis switching is not observed. The investigation also revealed that pressure plays a major role in determining the thermodynamic transition of the elliptical jet only for the case of supercritical jet injected into subcritical chamber conditions. At larger pressures, the supercritical jet undergoes disintegration and formation of droplets in the subcritical environment is observed. However, for supercritical jet injection into supercritical environment, the gas-gas like mixing behavior is observed

Influence of spatial curvature of a liquid jet on the rainbow positions: Ray tracing and experimental study

Science.gov (United States)

Duan, Qingwei; Zhong, Ruliang; Han, Xiang'e.; Ren, Kuan Fang

2017-07-01

Rainbow refractometry is largely used in optical metrology of particles thanks to its advantages of being non-intrusive, precise and fast. Many authors have contributed to its development and the application in the characterization of liquid jets/droplets. The researches reported in the literature are mainly for the spherical droplets or the liquid jets which can be considered as a cylinder of constant section. However, the section of a real liquid jet, even in the simplest configuration, varies with distance from the exit. The influence of the spatial curvature of the jets must, therefore, be taken into account. In this paper, we report experimental measurements of the shifts of the rainbow positions in the horizontal and vertical directions of a liquid jet and the theoretical investigation with the vectorial complex ray model. It is shown that the shifts of rainbow positions are very sensitive to the spatial curvature of the jets. This work is hoped to provide a new approach to characterizing the structure and the instability of liquid jets.

Hydrodynamics of slug flow in a vertical narrow rectangular channel under laminar flow condition

International Nuclear Information System (INIS)

Wang, Yang; Yan, Changqi; Cao, Xiaxin; Sun, Licheng; Yan, Chaoxing; Tian, Qiwei

2014-01-01

Highlights: • Slug flow hydrodynamics in a vertical narrow rectangular duct were investigated. • The velocity of trailing Taylor bubble undisturbed by the leading one was measured. • Correlation of Taylor bubble velocity with liquid slug length ahead it was proposed. • Evolution of length distributions of Taylor bubble and liquid slug was measured. • The model of predicted length distributions was applied to the rectangular channel. - Abstract: The hydrodynamics of gas–liquid two-phase slug flow in a vertical narrow rectangular channel with the cross section of 2.2 mm × 43 mm is investigated using a high speed video camera system. Simultaneous measurements of velocity and duration of Taylor bubble and liquid slug made it possible to determine the length distributions of the liquid slug and Taylor bubble. Taylor bubble velocity is dependent on the length of the liquid slug ahead, and an empirical correlation is proposed based on the experimental data. The length distributions of Taylor bubbles and liquid slugs are positively skewed (log-normal distribution) at all measuring positions for all flow conditions. A modified model based on that for circular tubes is adapted to predict the length distributions in the present narrow rectangular channel. In general, the experimental data is well predicted by the modified model

An Experimental Study of the Structure of Turbulent Non-Premixed Jet Flames in Microgravity

Science.gov (United States)

Boxx, Isaac; Idicheria, Cherian; Clemens, Noel

2000-11-01

The aim of this work is to investigate the structure of transitional and turbulent non-premixed jet flames under microgravity conditions. The microgravity experiments are being conducted using a newly developed drop rig and the University of Texas 1.5 second drop tower. The rig itself measures 16”x33”x38” and contains a co-flowing round jet flame facility, flow control system, CCD camera, and data/image acquisition computer. These experiments are the first phase of a larger study being conducted at the NASA Glenn Research Center 2.2 second drop tower facility. The flames being studied include methane and propane round jet flames at jet exit Reynolds numbers as high as 10,000. The primary diagnostic technique employed is emission imaging of flame luminosity using a relatively high-speed (350 fps) CCD camera. The high-speed images are used to study flame height, flame tip dynamics and burnout characteristics. Results are compared to normal gravity experimental results obtained in the same apparatus.

Experimental perforation of tubing with a hydraulic sand jet

Energy Technology Data Exchange (ETDEWEB)

Semenov, Yu V

1970-01-01

A series of field tests has shown that perforation with a hydraulic sand jet improves the quality of well completion. The sand jet does not crack the cement sheath or the casing, and the perforations are larger and deeper than perforations formed by explosive charges. Fluid circulation during sand jet perforation can safely be stopped for at least 10 min. Water containing a surfactant can be used as a sand carrier. Sand jet perforation allows successful completion of wells cased by 2 tubing strings. Sand jet perforation can be used to clean the borehole well and to remove foreign objects from the well.

Experimental verification of the axial and lateral stiffness of large W7-X rectangular bellows

International Nuclear Information System (INIS)

Reich, J.; Cardella, A.; Koppe, T.; Missal, B.; Capriccioli, A.; Loehrer, W.; Langone, S.; Sassone, P.C.

2006-01-01

The WENDELSTEIN 7-X (W7-X) is a super-conducting helical advanced stellarator. W7-X is provided with 299 ports, which connect the plasma vessel with the outer vessel. All the ports are equipped with bellows, which, during bake-out and final adjustment, compensate the relative movements of the vessels. The bellows have different shapes and dimensions ranging from 100 mm circular to 1170 x 570 mm rectangular sizes. During various load-cases the axial and lateral stiffness of all bellows will create a resulting spring-force which acts on the supports of the vessels directly. The higher the stiffness the more is the significant influence on the supports. The lateral stiffness which was calculated with the established standard EJMA-code (Expansion Joint Manufacturers Association) seemed to be relatively small. This appeared to be not correct in particular for non circular bellows. That is why the stiffness of rectangular, multi-layer bellows have then been re-calculated with the Finite Element Method (FEM) code ANSYS. The maximum difference between the FEM and EJMA code resulted to be up to 250 % in particular with movements along the longer side of the bellows. In order to clarify the differences a test-campaign with the largest rectangular bellows was performed. A special test rack allowed predefined displacements in pure lateral and axial directions taking into consideration of the friction in the moving elements. During the tests the load-displacement diagram was recorded permanently. The outcome of the FEM-results was then verified by the tests in axial and lateral directions. The EJMA-code is well proved for circular bellows. The tests showed that instead any calculation of rectangular bellows has to be confirmed by experiments. The paper summarises the calculation, describes the test activities, the apparatus and reports the final results. (author)

Measurements and Predictions of the Noise from Three-Stream Jets

Science.gov (United States)

Henderson, Brenda S.; Leib, Stewart J.; Wernet, Mark P.

2015-01-01

An experimental and numerical investigation of the noise produced by high-subsonic and supersonic three-stream jets was conducted. The exhaust system consisted of externally-mixed-convergent nozzles and an external plug. Bypass- and tertiary-to-core area ratios between 1.0 and 2.5, and 0.4 and 1.0, respectively, were studied. Axisymmetric and offset tertiary nozzles were investigated for heated and unheated conditions. For axisymmetric configurations, the addition of the third stream was found to reduce peak- and high-frequency acoustic levels in the peak-jet-noise direction, with greater reductions at the lower bypass-to-core area ratios. For the offset configurations, an offset duct was found to decrease acoustic levels on the thick side of the tertiary nozzle relative to those produced by the simulated two-stream jet with up to 8 dB mid-frequency noise reduction at large angles to the jet inlet axis. Noise reduction in the peak-jet-noise direction was greater for supersonic core speeds than for subsonic core speeds. The addition of a tertiary nozzle insert used to divert the third-stream jet to one side of the nozzle system provided no noise reduction. Noise predictions are presented for selected cases using a method based on an acoustic analogy with mean flow interaction effects accounted for using a Green's function, computed in terms of its coupled azimuthal modes for the offset cases, and a source model previously used for round and rectangular jets. Comparisons of the prediction results with data show that the noise model predicts the observed increase in low-frequency noise with the introduction of a third, axisymmetric stream, but not the high-frequency reduction. For an offset third stream, the model predicts the observed trend of decreased sound levels on the thick side of the jet compared with the thin side, but the predicted azimuthal variations are much less than those seen in the data. Also, the shift of the spectral peak to lower frequencies with

Vector boson tagged jets and jet substructure

Directory of Open Access Journals (Sweden)

Vitev Ivan

2018-01-01

Full Text Available In these proceedings, we report on recent results related to vector boson-tagged jet production in heavy ion collisions and the related modification of jet substructure, such as jet shapes and jet momentum sharing distributions. Z0-tagging and γ-tagging of jets provides new opportunities to study parton shower formation and propagation in the quark-gluon plasma and has been argued to provide tight constrains on the energy loss of reconstructed jets. We present theoretical predictions for isolated photon-tagged and electroweak boson-tagged jet production in Pb+Pb collisions at √sNN = 5.02 TeV at the LHC, addressing the modification of their transverse momentum and transverse momentum imbalance distributions. Comparison to recent ATLAS and CMS experimental measurements is performed that can shed light on the medium-induced radiative corrections and energy dissipation due to collisional processes of predominantly quark-initiated jets. The modification of parton splitting functions in the QGP further implies that the substructure of jets in heavy ion collisions may differ significantly from the corresponding substructure in proton-proton collisions. Two such observables and the implication of tagging on their evaluation is also discussed.

Numerical and experimental study on the steady cone-jet mode of electro-centrifugal spinning

Science.gov (United States)

Hashemi, Ali Reza; Pishevar, Ahmad Reza; Valipouri, Afsaneh; Pǎrǎu, Emilian I.

2018-01-01

This study focuses on a numerical investigation of an initial stable jet through the air-sealed electro-centrifugal spinning process, which is known as a viable method for the mass production of nanofibers. A liquid jet undergoing electric and centrifugal forces, as well as other forces, first travels in a stable trajectory and then goes through an unstable curled path to the collector. In numerical modeling, hydrodynamic equations have been solved using the perturbation method—and the boundary integral method has been implemented to efficiently solve the electric potential equation. Hydrodynamic equations have been coupled with the electric field using stress boundary conditions at the fluid-fluid interface. Perturbation equations were discretized by a second order finite difference method, and the Newton method was implemented to solve the discretized non-linear system. Also, the boundary element method was utilized to solve electrostatic equations. In the theoretical study, the fluid was described as a leaky dielectric with charges only on the surface of the jet traveling in dielectric air. The effect of the electric field induced around the nozzle tip on the jet instability and trajectory deviation was also experimentally studied through plate-plate geometry as well as point-plate geometry. It was numerically found that the centrifugal force prevails on electric force by increasing the rotational speed. Therefore, the alteration of the applied voltage does not significantly affect the jet thinning profile or the jet trajectory.

A free-jet experimental study on the performance of a cavity-type ramjet

Energy Technology Data Exchange (ETDEWEB)

Tan, Jianguo; Pan, Yu; Liang, Jianhan; Wang, Zhenguo [National University of Defense Technology, ChangSha (China)

2011-11-15

Free jet experiments have been conducted to evaluate the performance of a cavity-type ramjet. To prevent uncertainty of combustion parameters, a method to calculate internal thrust from cold flow parameters is brought forward. According to this analysis method, the internal thrust of the cavity-type ramjet increases linearly with the stoichiometric ratio while the specific impulse decreases squarely. The aero-propulsive balance of a conceptive missile is also examined, focusing on the effect of attack angle. Considering both efficiency and performance, an attack angle of 3{approx}6 degrees is recommended. And the free-jet experimental results show that the cavity-type ramjet can supply sufficient thrust for the missile under cruise conditions.

Sound absorption effects in a rectangular enclosure with the foamed aluminum sheet absorber

International Nuclear Information System (INIS)

Oh, Jae Eung; Chung, Jin Tai; Kim, Sang Hun; Chung, Kyung Ryul

1998-01-01

For the purpose of finding out the optimal thickness of sound absorber and the sound absorption effects due to the selected thickness at an interested frequency range, the analytical study identifies the interior and exterior sound field characteristics of a rectangular enclosure with foamed aluminum lining and the experimental verification is performed with random noise input. By using a two-microphone impedance tube, we measure experimentally the absorption coefficient and the impedance of simple sound absorbing materials. Measured acoustical parameters of the test samples are applied to the theoretical analysis to predict sound pressure field in the cavity. The sound absorption effects from measurements are compared to predicted ones in both cases with and without foamed aluminum lining in the cavity of the rectangular enclosure

Study on critical heat flux based on wavelet transform in rectangular narrow channels

International Nuclear Information System (INIS)

Zhou Tao; Ju Zhongyun; Zhang Lei; Li Jingjing; Sheng Cheng; Xiao Zejun

2014-01-01

Critical heat flux is very important for the safety of nuclear reactor, and observing temperature rise rate is a feasible method. The wavelet transform is used to analyze the CHF temperature rise curves in rectangular narrow channels, which can remove relative weaker interference and effectively judge CHF. Rectangular narrow channel can strengthen heat transfer and reduce CHF, whose characteristics are proved by temperature rise curves analyzed by wavelet transform. Respectively applying Daubechies function and Haar function is to guarantee the accuracy of the wavelet analysis, and Daubechies function is more accurate than Haar function in the detail signal processing from results. While the wavelet analysis and experimental results are compared and found in good agreement with the experimental results. (authors)

Experimental study on downward two-phase flow in narrow rectangular channel

Energy Technology Data Exchange (ETDEWEB)

Kim, T.H.; Jeong, J.H. [Pusan National Univ., Busan (Korea, Republic of)

2014-07-01

Adiabatic vertical two-phase flow of air and water through narrow rectangular channels was investigated. This study involved the observation of flow using a high speed camera and flow regimes were determined by image processing program using a MATLAB. The flows regimes in channel with downward flow are similar to those found by previous studies with upward flow. The flow regimes in downward flow at low liquid velocity are different from the previous studies in upward flow. The flow regimes can be classified into bubbly, cap-bubbly, slug and churn flow. (author)

An experimental study on turbulent lifted flames of methane in coflow jets at elevated temperatures

KAUST Repository

Choi, Byungchul; Chung, Suk-Ho

2013-01-01

An experimental study was conducted on the effects of initial temperature variation on the stabilization characteristics of turbulent nonpremixed flames in coflow jets of methane fuel diluted by nitrogen. The typical behavior seen in the study

Jets from jets: re-clustering as a tool for large radius jet reconstruction and grooming at the LHC

Science.gov (United States)

Nachman, Benjamin; Nef, Pascal; Schwartzman, Ariel; Swiatlowski, Maximilian; Wanotayaroj, Chaowaroj

2015-02-01

Jets with a large radius R ≳ 1 and grooming algorithms are widely used to fully capture the decay products of boosted heavy particles at the Large Hadron Collider (LHC). Unlike most discriminating variables used in such studies, the jet radius is usually not optimized for specific physics scenarios. This is because every jet configuration must be calibrated, insitu, to account for detector response and other experimental effects. One solution to enhance the availability of large- R jet configurations used by the LHC experiments is jet re-clustering. Jet re-clustering introduces an intermediate scale r groomed jets. Jet re-clustering has the benefit that no additional large-R calibration is necessary, allowing the re-clustered large radius parameter to be optimized in the context of specific precision measurements or searches for new physics.

Experimental investigation of the formation and propagation of plasma jets created by a power laser: application to laboratory astrophysics

International Nuclear Information System (INIS)

Loupias, B.

2008-10-01

Plasma jets are often observed in the polar regions of Young Stellar Objects (YSO). For a better understanding of the whole processes at the origin of their formation and evolution, this research thesis aims at demonstrating the feasibility of a plasma jet generation by a power laser, and at investigating its characteristics. After a detailed description of Young Stellar Objects jets and an overview of theoretical models, the author describes some experiments performed with gas guns, pulsed machines and power lasers. He describes means of generation of a jet by laser interaction via strong shock propagation. He reports experimental work, describing the target, laser operating conditions and the determination of jet parameters: speed, temperature, density. Then, he introduces results obtained for plasma jet propagation in vacuum, describes their evolution with respect to initial conditions (target type, laser operating conditions), and identifies optimal conditions for generating a jet similar to that in astrophysical conditions. He considers their propagation in ambient medium like for YSO jets in interstellar medium. Two distinct cases are investigated: collision of two successive shocks in a gaseous medium, and propagation of a plasma jet in a gas jet

Experimental and numerical investigations of wire bending by linear winding of rectangular tooth coils

Science.gov (United States)

Komodromos, A.; Tekkaya, A. E.; Hofmann, J.; Fleischer, J.

2018-05-01

Since electric motors are gaining in importance in many fields of application, e.g. hybrid electric vehicles, optimization of the linear coil winding process greatly contributes to an increase in productivity and flexibility. For the investigation of the forming behavior of the winding wire the material behavior is characterized in different experimental setups. Numerical examinatons of the linear winding process are carried out in a case study for a rectangular bobbin in order to analyze the influence of forming parameters on the resulting properties of the wound coil. Besides the numerical investigation of the linear winding method by using the finite element method (FEM), a multi-body dynamics (MBD) simulation is carried out. The multi-body dynamics simulation is necessary to represent the movement of the bodies as well as the connection of the components during winding. The finite element method is used to represent the material behavior of the copper wire and the plastic strain distribution within the wire. It becomes clear that the MBD simulation is not sufficient for analyzing the process and the wire behavior in its entirety. Important parameters that define the final coil properties cannot be analyzed in the manner of a precise manifestation, e.g. the clearance between coil bobbin and wire as well as the wire deformation behavior in form of a diameter reduction which negatively affects the ohmic resistance. Finally, the numerical investigations are validated experimentally by linear winding tests.

Jets from jets: re-clustering as a tool for large radius jet reconstruction and grooming at the LHC

Energy Technology Data Exchange (ETDEWEB)

Nachman, Benjamin; Nef, Pascal; Schwartzman, Ariel; Swiatlowski, Maximilian [SLAC National Accelerator Laboratory, Stanford University,2575 Sand Hill Rd, Menlo Park, CA 94025 (United States); Wanotayaroj, Chaowaroj [Center for High Energy Physics, University of Oregon,1371 E. 13th Ave, Eugene, OR 97403 (United States)

2015-02-12

Jets with a large radius R≳1 and grooming algorithms are widely used to fully capture the decay products of boosted heavy particles at the Large Hadron Collider (LHC). Unlike most discriminating variables used in such studies, the jet radius is usually not optimized for specific physics scenarios. This is because every jet configuration must be calibrated, insitu, to account for detector response and other experimental effects. One solution to enhance the availability of large-R jet configurations used by the LHC experiments is jet re-clustering. Jet re-clustering introduces an intermediate scale rjets are calibrated and used as the inputs to reconstruct large radius jets. In this paper we systematically study and propose new jet re-clustering configurations and show that re-clustered large radius jets have essentially the same jet mass performance as large radius groomed jets. Jet re-clustering has the benefit that no additional large-R calibration is necessary, allowing the re-clustered large radius parameter to be optimized in the context of specific precision measurements or searches for new physics.

Jets from jets: re-clustering as a tool for large radius jet reconstruction and grooming at the LHC

International Nuclear Information System (INIS)

Nachman, Benjamin; Nef, Pascal; Schwartzman, Ariel; Swiatlowski, Maximilian; Wanotayaroj, Chaowaroj

2015-01-01

Jets with a large radius R≳1 and grooming algorithms are widely used to fully capture the decay products of boosted heavy particles at the Large Hadron Collider (LHC). Unlike most discriminating variables used in such studies, the jet radius is usually not optimized for specific physics scenarios. This is because every jet configuration must be calibrated, insitu, to account for detector response and other experimental effects. One solution to enhance the availability of large-R jet configurations used by the LHC experiments is jet re-clustering. Jet re-clustering introduces an intermediate scale rjets are calibrated and used as the inputs to reconstruct large radius jets. In this paper we systematically study and propose new jet re-clustering configurations and show that re-clustered large radius jets have essentially the same jet mass performance as large radius groomed jets. Jet re-clustering has the benefit that no additional large-R calibration is necessary, allowing the re-clustered large radius parameter to be optimized in the context of specific precision measurements or searches for new physics.

Experimental and Monte Carlo simulated spectra of a liquid-metal-jet x-ray source

International Nuclear Information System (INIS)

Marziani, M.; Gambaccini, M.; Di Domenico, G.; Taibi, A.; Cardarelli, P.

2014-01-01

A prototype x-ray system based on a liquid-metal-jet anode was evaluated within the framework of the LABSYNC project. The generated spectrum was measured using a CZT-based spectrometer and was compared with spectra simulated by three Monte Carlo codes: MCNPX, PENELOPE and EGS5. Notable differences in the simulated spectra were found. These are mainly attributable to differences in the models adopted for the electron-impact ionization cross section. The simulation that more closely reproduces the experimentally measured spectrum was provided by PENELOPE. - Highlights: • The x-ray spectrum of a liquid-jet x-ray anode was measured with a CZT spectrometer. • Results were compared with Monte Carlo simulations using MCNPX, PENELOPE, EGS5. • Notable differences were found among the Monte Carlo simulated spectra. • The key role was played by the electron-impact ionization cross-section model used. • The experimentally measured spectrum was closely reproduced by the PENELOPE code

Development of an empirical correlation for flow characteristics of turbulent jet by steam jet condensation

International Nuclear Information System (INIS)

Kang, H. S.; Kim, Y. S.; Youn, Y. J.; Song, C. H.

2008-01-01

An experimental research was performed to develop an empirical correlation of the turbulent water jet induced by the steam jet through a single hole in a subcooled water pool. A moveable pitot tube including a thermal couple was used to measure a local velocity and temperature of the turbulent water jet. The experimental results show that the velocity and the temperature distributions agree well with the theory of axially symmetric turbulent jet. The correlation predicting the maximum velocity of the turbulent jet was modified from the previous correlation and a new correlation to predict the characteristic length was developed based on the test results

Partitioning sparse rectangular matrices for parallel processing

Energy Technology Data Exchange (ETDEWEB)

Kolda, T.G.

1998-05-01

The authors are interested in partitioning sparse rectangular matrices for parallel processing. The partitioning problem has been well-studied in the square symmetric case, but the rectangular problem has received very little attention. They will formalize the rectangular matrix partitioning problem and discuss several methods for solving it. They will extend the spectral partitioning method for symmetric matrices to the rectangular case and compare this method to three new methods -- the alternating partitioning method and two hybrid methods. The hybrid methods will be shown to be best.

Partial rectangular metric spaces and fixed point theorems.

Science.gov (United States)

Shukla, Satish

2014-01-01

The purpose of this paper is to introduce the concept of partial rectangular metric spaces as a generalization of rectangular metric and partial metric spaces. Some properties of partial rectangular metric spaces and some fixed point results for quasitype contraction in partial rectangular metric spaces are proved. Some examples are given to illustrate the observed results.

Simulation and experimental investigation of inner-jet electrochemical grinding of GH4169 alloy

Directory of Open Access Journals (Sweden)

Hansong LI

2018-03-01

Full Text Available GH4169 alloy is one of the most commonly used materials in aero engine turbine blades, but its machinability is poor because of its excellent strength at high temperatures. Electrochemical machining (ECM has become a common method for machining this alloy and other difficult-to-machine materials. Electrochemical grinding (ECG is a hybrid process combining ECM and conventional grinding. In this paper, investigations conducted on inner-jet ECG of GH4169 alloy are described. Two types of inner-jet ECG grinding wheels were used to machine a flat bottom surface. The machining process was simulated using COMSOL software, and machining gaps under different machining parameters were obtained. In addition, maximum feed rates and maximum material removal rates under different machining parameters were studied experimentally. The maximum sizes and the uniformity of the distributions of the gaps machined by the two grinding wheels were compared. The effects of different applied voltages on the machining results were also investigated. Keywords: Electrochemical grinding, GH4169 alloy, Inner-jet, Material removal rate, Maximum feed rate

Numerical and experimental investigation on static electric charge model at stable cone-jet region

Science.gov (United States)

Hashemi, Ali Reza; Pishevar, Ahmad Reza; Valipouri, Afsaneh; Pǎrǎu, Emilian I.

2018-03-01

In a typical electro-spinning process, the steady stretching process of the jet beyond the Taylor cone has a significant effect on the dimensions of resulting nanofibers. Also, it sets up the conditions for the onset of the bending instability. The focus of this work is the modeling and simulation of the initial stable jet phase seen during the electro-spinning process. The perturbation method was applied to solve hydrodynamic equations, and the electrostatic equation was solved by a boundary integral method. These equations were coupled with the stress boundary conditions derived appropriate at the fluid-fluid interface. Perturbation equations were discretized by the second-order finite difference method, and the Newton method was implemented to solve the discretized nonlinear system. Also, the boundary element method was utilized to solve the electrostatic equation. In the theoretical study, the fluid is described as a leaky dielectric with charges only on the jet surface in dielectric air. In this study, electric charges were modeled as static. Comparison of numerical and experimental results shows that at low flow rates and high electric field, good agreement was achieved because of the superior importance of the charge transport by conduction rather than convection and charge concentration. In addition, the effect of unevenness of the electric field around the nozzle tip was experimentally studied through plate-plate geometry as well as point-plate geometry.

JET Joint Undertaking

International Nuclear Information System (INIS)

Keen, B.E.; Lallia, P.; O'Hara, G.W.; Pollard, I.E.

1987-06-01

The paper presents the annual report of the Joint European Torus (JET) Joint Undertaking, 1986. The report is divided into two parts: a part on the scientific and technical programme of the project, and a part setting out the administration and organisation of the Project. The first part includes: a summary of the main features of the JET apparatus, the JET experimental programme, the position of the Project in the overall Euratom programme, and how JET relates to other large fusion devices throughout the world. In addition, the technical status of JET is described, as well as the results of the JET operations in 1986. The final section of the first part outlines the proposed future programme of JET. (U.K.)

Glow plasma jet - experimental study of a transferred atmospheric pressure glow discharge

International Nuclear Information System (INIS)

Guerra-Mutis, Marlon H; U, Carlos V Pelaez; H, Rafael Cabanzo

2003-01-01

In this paper we present the experimental study of a glow plasma jet (GPJ) obtained from a transferred atmospheric pressure glow discharge (APGD) operating at 60 Hz. The characterization of the emission spectra for both electrical discharges is presented and the electrical circuit features for APGD generation are discussed. The potentiality of GPJ as a source of active species for depletion of contaminants in liquid hydrocarbon fractions is also established

Experimental study of the electron-atom Bremsstrahlung emission in an argon plasma jet

International Nuclear Information System (INIS)

Ranson, P.; Vallee, O.; Chapelle, J.

1977-01-01

Electron-neutral atom bremsstrahlung is studied between 0.4 μm and 5 μm in a decaying argon plasma jet; in visible and infra-red range, some discrepancies appear between experimental results and theoretical calculations of different authors (Geltman, Stallcop). In the infra-red, the discrepancy can be partly explained because theoretical elastic cross sections are higher than experimental values in the vicinity of the Ramsauer minimum. In the visible range, a very small amount of fast electrons due to superelastic and recombination collisions explain the observed discrepancy [fr

Numerical Investigation on Sensitivity of Liquid Jet Breakup to Physical Fuel Properties with Experimental Comparison

Science.gov (United States)

Kim, Dokyun; Bravo, Luis; Matusik, Katarzyna; Duke, Daniel; Kastengren, Alan; Swantek, Andy; Powell, Christopher; Ham, Frank

2016-11-01

One of the major concerns in modern direct injection engines is the sensitivity of engine performance to fuel characteristics. Recent works have shown that even slight differences in fuel properties can cause significant changes in efficiency and emission of an engine. Since the combustion process is very sensitive to the fuel/air mixture formation resulting from disintegration of liquid jet, the precise assessment of fuel sensitivity on liquid jet atomization process is required first to study the impact of different fuels on the combustion. In the present study, the breaking process of a liquid jet from a diesel injector injecting into a quiescent gas chamber is investigated numerically and experimentally for different liquid fuels (n-dodecane, iso-octane, CAT A2 and C3). The unsplit geometric Volume-of-Fluid method is employed to capture the phase interface in Large-eddy simulations and results are compared against the radiography measurement from Argonne National Lab including jet penetration, liquid mass distribution and volume fraction. The breakup characteristics will be shown for different fuels as well as droplet PDF statistics to demonstrate the influences of the physical properties on the primary atomization of liquid jet. Supported by HPCMP FRONTIER award, US DOD, Office of the Army.

Active control of continuous air jet with bifurcated synthetic jets

Directory of Open Access Journals (Sweden)

Dančová Petra

2017-01-01

Full Text Available The synthetic jets (SJs have many significant applications and the number of applications is increasing all the time. In this research the main focus is on the primary flow control which can be used effectively for the heat transfer increasing. This paper deals with the experimental research of the effect of two SJs worked in the bifurcated mode used for control of an axisymmetric air jet. First, the control synthetic jets were measured alone. After an adjustment, the primary axisymmetric jet was added in to the system. For comparison, the primary flow without synthetic jets control was also measured. All experiments were performed using PIV method whereby the synchronization between synthetic jets and PIV system was necessary to do.

Numerical simulation of sand jet in water

Energy Technology Data Exchange (ETDEWEB)

Azimi, A.H.; Zhu, D.; Rajaratnam, N. [Alberta Univ., Edmonton, AB (Canada). Dept. of Civil and Environmental Engineering

2008-07-01

A numerical simulation of sand jet in water was presented. The study involved a two-phase flow using two-phase turbulent jets. A literature review was also presented, including an experiment on particle laden air jet using laser doppler velocimetry (LDV); experiments on the effect of particle size and concentration on solid-gas jets; an experimental study of solid-liquid jets using particle image velocimetry (PIV) technique where mean velocity and fluctuations were measured; and an experimental study on solid-liquid jets using the laser doppler anemometry (LDA) technique measuring both water axial and radial velocities. Other literature review results included a photographic study of sand jets in water; a comparison of many two-phase turbulent flow; and direct numerical simulation and large-eddy simulation to study the effect of particle in gas jet flow. The mathematical model and experimental setup were also included in the presentation along with simulation results for sand jets, concentration, and kinetic energy. The presentation concluded with some proposed future studies including numerical simulation of slurry jets in water and numerical simulation of slurry jets in MFT. tabs., figs.

Free vibration analysis of rectangular plates with central cutout

Directory of Open Access Journals (Sweden)

Kanak Kalita

2016-12-01

Full Text Available A nine-node isoparametric plate element in conjunction with first-order shear deformation theory is used for free vibration analysis of rectangular plates with central cutouts. Both thick and thin plate problems are solved for various aspect ratios and boundary conditions. In this article, primary focus is given to the effect of rotary inertia on natural frequencies of perforated rectangular plates. It is found that rotary inertia has significant effect on thick plates, while for thin plates the rotary inertia term can be ignored. It is seen that the numerical convergence is very rapid and based on comparison with experimental and analytical data from literature, it is proposed that the present formulation is capable of yielding highly accurate results. Finally, some new numerical solutions are provided here, which may serve as benchmark for future research on similar problems.

Critical heat flux of subcooled flow boiling in narrow rectangular channels

International Nuclear Information System (INIS)

Kureta, Masatoshi; Akimoto, Hajime

1999-01-01

In relation to the high-heat-load devices such as a solid-target cooling channel of a high-intensity neutron source, burnout experiments were performed to obtain critical heat flux (CHF) data systematically for vertical upward flow in one-side heated rectangular channels. One of the objectives of this study was to study an extensibility of existing CHF correlations and models, which were proposed for a round tube, to rectangular channels for design calculation. Existing correlations and models were reviewed and compared with obtained data. Sudo's thin liquid layer dryout model, Griffel correlation and Bernath correlation were in good agreement with the experimental data for short-heated-length and low inlet water temperature conditions. (author)

Experimental investigation of the charge/discharge process for an organic PCM macroencapsulated in an aluminium rectangular cavity

Science.gov (United States)

Bejan, Andrei-Stelian; Labihi, Abdelouhab; Croitoru, Cristiana Verona; Catalina, Tiberiu; Chehouani, Hassan; Benhamou, Brahim

2018-02-01

Buildings sector has one of the highest potential regarding the reduction of greenhouse gases emissions, as being responsible for more than 40% of energy consumption worldwide. This is why, in order to achieve indoor thermal comfort, it is mandatory to use energy-efficient systems. Materials acting as thermal energy storage (TES) represents one of the most effective strategy that can be implemented and nowadays, many studies are focusing their attention on latent heat storage, respectively on phase changing materials (PCM) which can embed a large embed a high quantity of energy, unlike classic materials acting as thermal mass. This purpose of this paper is to experimentally investigate the charge and discharge processes for an organic PCM (RT35 paraffin) macroencapsulated in an aluminium rectangular cavity which was placed first in a horizontal position and after in a vertical position. After several experimental campaigns conducted we determined that the vertical position enhance the heat transfer because of the natural convection which occurs inside the cavity. Therefore, the charging time is lower in case of the vertical cavity and the temperature measured inside and on the surface is higher.

Droplet size in a rectangular Venturi scrubber

OpenAIRE

Costa, M. A. M.; Henrique, P. R.; Gonçalves, J. A. S.; Coury, J.R.

2004-01-01

The Venturi scrubber is a device which uses liquid in the form of droplets to efficiently remove fine particulate matter from gaseous streams. Droplet size is of fundamental importance for the scrubber performance. In the present experimental study, a laser diffraction technique was used in order to measure droplet size in situ in a Venturi scrubber with a rectangular cross section. Droplet size distribution was measured as a function of gas velocity (58.3 to 74.9 m/s), liquid-to-gas ratio (0...

Experimental study of a water-mist jet issuing normal to a heated flat plate

Directory of Open Access Journals (Sweden)

Vouros Andreas

2016-01-01

Full Text Available A parametric experimental study on the development of a round jet spray impacting a smooth, heated, flat plate has been accomplished. The main objective of this effort was to provide information characterizing the flow structure of a developing mist jet, issuing vertically towards an upward facing, horizontal heated plate, by means of simultaneous droplet size and velocity measurements. Phase Doppler Anemometry was used, providing also information on liquid volume flux. The fine spray of small atomized droplets (0.5-5.0 μm, was generated using a medical nebulizer. Two low Reynolds number jets (Re=2952, 3773 issuing from a cylindrical pipe have been tested. The distance between the jets’ exit and the plate was 50 cm. A stainless steel non-magnetic flat plate of dimensions 1000x500x12mm3 was used as target wall. Constant heat flux boundary conditions were established during measurements. Results indicate that the heat flux from the plate is influencing the evolution of the spray jet, diminishing its velocity and turbulence. Average droplet sizes are affected little by the heat flux, although for the non-heated sprays, droplet sizes increase at locations very close to the plate. A significant effect on droplet volume flow rate is also reported.

Experimental Investigation of Thermohydraulic Performance of a Rectangular Solar Air Heater Duct Equipped with V-Shaped Perforated Blocks

Directory of Open Access Journals (Sweden)

Tabish Alam

2014-01-01

Full Text Available This paper presents the thermohydraulic performance of rectangular solar air heater duct equipped with V-shaped rectangular perforated blocks attached to the heated surface. The V-shaped perforated blocks are tested for downstream (V-down to the air flow at Reynolds number from 2000 to 20000. The perforated blocks have relative pitch ratio (P/e from 4 to 12, relative blockage height ratio (e/H from 0.4 to 1.0, and open area ration from 5% to 25% at a fixed value of angle of attack of 60∘ in a rectangular duct having duct aspect ratio (W/H of 12. Thermohydraulic performance is compared at different geometrical parameters of V-shaped perforated blocks for equal pumping power which shows that maximum performance is observed at a relative pitch of 8, relative rib height of 0.8, and open area ration of 20%. It is also observed that the performance of V-shaped perforated blocks was better than transverse-perforated blocks.

Experimental study of gas-liquid flow local characteristics in rectangular microchannel

Directory of Open Access Journals (Sweden)

Bartkus German

2017-01-01

Full Text Available Using high-speed video recording and the method of dual laser scanning the gas-liquid flow was investigated in a rectangular microchannel with an aspect ratio of 0.74 (cross section 269×362 μm. The T-mixer was used at the channel’s inlet for the two-phase flow formation. The peculiarity of this work is using a number of liquids (ethanol, distilled water, 40% aqueous ethanol with different physical properties, including surface tension, viscosity, and density, with nitrogen. Experiments were carried out for the vertically upward and horizontal flow. Using laser scanning method the maps of flow patterns were obtained for all mixtures.

Axis-switching of a micro-jet

Science.gov (United States)

Cabaleiro, Juan Martin; Aider, Jean-Luc

2014-03-01

In this study, it is shown that free microjets can undergo complex transitions similar to large-scale free jets despite relatively low Reynolds numbers. Using an original experimental method allowing for the 3D reconstruction of the instantaneous spatial organization of the microjet, the axis-switching of a micro-jet is observed for the first time. This is the first experimental evidence of such complex phenomena for free micro-jets. Combining these experimental results with Direct Numerical Simulations it is shown that the mechanism responsible for the axis-switching is the deformation of a micro-vortex ring due to induction by the corner vortices, as it occurs in large scale non-circular jets.

Numerical investigation of boiling heat transfer on hydrocarbon mixture refrigerant in vertical rectangular minichannel

Directory of Open Access Journals (Sweden)

Huixing Li

2016-05-01

Full Text Available In order to investigate the characteristics of boiling heat transfer for hydrocarbon mixture refrigerant in plate-fin heat exchanger which is used in the petrochemical industry field, a model was established on boiling heat transfer in vertical rectangular channel. The simulated results were compared with the experimental data from literature. The results show that the deviation between the simulated results and experimental data is within ±15%. Meanwhile, the characteristic of boiling heat transfer was investigated in vertical rectangular minichannel of plate-fin heat exchanger. The results show that the boiling heat transfer coefficient increases with the increase in quality and mass flux and is slightly impacted by the heat flux. This is because that the main boiling mechanism is forced convective boiling while the contribution of nucleate boiling is slight. The correlation of Liu and Winterton is in good agreement with the simulation results. The deviation between correlation calculations and simulation results is mostly less than ±15%. These results will provide some constructive instructions for the understanding of saturated boiling mechanism in a vertical rectangular minichannel and the prediction of heat transfer performance in plate-fin heat exchanger.

An experimental study on turbulent lifted flames of methane in coflow jets at elevated temperatures

KAUST Repository

Choi, Byungchul

2013-01-01

An experimental study was conducted on the effects of initial temperature variation on the stabilization characteristics of turbulent nonpremixed flames in coflow jets of methane fuel diluted by nitrogen. The typical behavior seen in the study showed that the liftoff height increased linearly with the jet velocity regardless of the initial temperature in the turbulent regime. Two models were investigated for predicting liftoff heights in the methane jets: the premixed flame model and the large-scale mixing model. For the premixed flame model, the liftoff heights in the methane jets were accurately predicted using the thermal diffusivity of the unburned gas temperature αst,0, instead of that of the burned gas temperature αst,b. For the large-scale mixing model, however, the prediction of liftoff heights differed slightly for the various fuel mole fractions. However, when considering the initial fuel mass fraction YF,0, the liftoff heights were successfully predicted. This result implies that the characteristics of the unburned fuel-air mixture play a crucial role for flame stabilization in coflow jets for a variety of initial conditions. In the turbulent regime, the blowout velocity and the liftoff height at blowout could be accurately predicted by the two models based on a consideration of the physical properties and the buoyancy effect of the initial temperature variation. © 2012 Elsevier Ltd. All rights reserved.

Experimental properties of gluon and quark jets from a point source

CERN Document Server

Abbiendi, G.; Alexander, G.; Allison, John; Altekamp, N.; Anderson, K.J.; Anderson, S.; Arcelli, S.; Asai, S.; Ashby, S.F.; Axen, D.; Azuelos, G.; Ball, A.H.; Barberio, E.; Barlow, Roger J.; Batley, J.R.; Baumann, S.; Bechtluft, J.; Behnke, T.; Bell, Kenneth Watson; Bella, G.; Bellerive, A.; Bentvelsen, S.; Bethke, S.; Betts, S.; Biebel, O.; Biguzzi, A.; Blobel, V.; Bloodworth, I.J.; Bock, P.; Bohme, J.; Bonacorsi, D.; Boutemeur, M.; Braibant, S.; Bright-Thomas, P.; Brigliadori, L.; Brown, Robert M.; Burckhart, H.J.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Chrisman, D.; Ciocca, C.; Clarke, P.E.L.; Clay, E.; Cohen, I.; Conboy, J.E.; Cooke, O.C.; Couyoumtzelis, C.; Coxe, R.L.; Cuffiani, M.; Dado, S.; Dallavalle, G.Marco; Davis, R.; De Jong, S.; de Roeck, A.; Dervan, P.; Desch, K.; Dienes, B.; Dixit, M.S.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Estabrooks, P.G.; Etzion, E.; Fabbri, F.; Fanfani, A.; Fanti, M.; Faust, A.A.; Fiedler, F.; Fierro, M.; Fleck, I.; Folman, R.; Frey, A.; Furtjes, A.; Futyan, D.I.; Gagnon, P.; Gary, J.W.; Gascon, J.; Gascon-Shotkin, S.M.; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Gibson, V.; Gibson, W.R.; Gingrich, D.M.; Glenzinski, D.; Goldberg, J.; Gorn, W.; Grandi, C.; Graham, K.; Gross, E.; Grunhaus, J.; Gruwe, M.; Hanson, G.G.; Hansroul, M.; Hapke, M.; Harder, K.; Harel, A.; Hargrove, C.K.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Herndon, M.; Herten, G.; Heuer, R.D.; Hildreth, M.D.; Hill, J.C.; Hobson, P.R.; Hoch, M.; Hocker, James Andrew; Hoffman, Kara Dion; Homer, R.J.; Honma, A.K.; Horvath, D.; Hossain, K.R.; Howard, R.; Huntemeyer, P.; Igo-Kemenes, P.; Imrie, D.C.; Ishii, K.; Jacob, F.R.; Jawahery, A.; Jeremie, H.; Jimack, M.; Jones, C.R.; Jovanovic, P.; Junk, T.R.; Kanzaki, J.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Kayal, P.I.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klier, A.; Kobayashi, T.; Kobel, M.; Kokott, T.P.; Kolrep, M.; Komamiya, S.; Kowalewski, Robert V.; Kress, T.; Krieger, P.; von Krogh, J.; Kuhl, T.; Kyberd, P.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Lauber, J.; Lautenschlager, S.R.; Lawson, I.; Layter, J.G.; Lee, A.M.; Lellouch, D.; Letts, J.; Levinson, L.; Liebisch, R.; List, B.; Littlewood, C.; Lloyd, A.W.; Lloyd, S.L.; Loebinger, F.K.; Long, G.D.; Losty, M.J.; Lu, J.; Ludwig, J.; Lui, D.; Macchiolo, A.; Macpherson, A.; Mader, W.; Mannelli, M.; Marcellini, S.; Markopoulos, C.; Martin, A.J.; Martin, J.P.; Martinez, G.; Mashimo, T.; Mattig, Peter; McDonald, W.John; McKenna, J.; Mckigney, E.A.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Menke, S.; Merritt, F.S.; Mes, H.; Meyer, J.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mir, R.; Mohr, W.; Montanari, A.; Mori, T.; Nagai, K.; Nakamura, I.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oakham, F.G.; Odorici, F.; Ogren, H.O.; Oreglia, M.J.; Orito, S.; Palinkas, J.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Patt, J.; Perez-Ochoa, R.; Petzold, S.; Pfeifenschneider, P.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poffenberger, P.; Poli, B.; Polok, J.; Przybycien, M.; Rembser, C.; Rick, H.; Robertson, S.; Robins, S.A.; Rodning, N.; Roney, J.M.; Rosati, S.; Roscoe, K.; Rossi, A.M.; Rozen, Y.; Runge, K.; Runolfsson, O.; Rust, D.R.; Sachs, K.; Saeki, T.; Sahr, O.; Sang, W.M.; Sarkisian, E.K.G.; Sbarra, C.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schieck, J.; Schmitt, S.; Schoning, A.; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Shepherd-Themistocleous, C.H.; Sherwood, P.; Siroli, G.P.; Sittler, A.; Skuja, A.; Smith, A.M.; Snow, G.A.; Sobie, R.; Soldner-Rembold, S.; Spagnolo, S.; Sproston, M.; Stahl, A.; Stephens, K.; Steuerer, J.; Stoll, K.; Strom, David M.; Strohmer, R.; Surrow, B.; Talbot, S.D.; Taras, P.; Tarem, S.; Teuscher, R.; Thiergen, M.; Thomas, J.; Thomson, M.A.; Torrence, E.; Towers, S.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turcot, A.S.; Turner-Watson, M.F.; Ueda, I.; Van Kooten, Rick J.; Vannerem, P.; Verzocchi, M.; Voss, H.; Wackerle, F.; Wagner, A.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wermes, N.; White, J.S.; Wilson, G.W.; Wilson, J.A.; Wyatt, T.R.; Yamashita, S.; Yekutieli, G.; Zacek, V.; Zer-Zion, D.

1999-01-01

Gluon jets are identified in hadronic Z0 decays as all the particles in a hemisphere opposite to a hemisphere containing two tagged quark jets. Gluon jets defined in this manner are equivalent to gluon jets produced from a color singlet point source and thus correspond to the definition employed for most theoretical calculations. In a separate stage of the analysis, we select quark jets in a manner to correspond to calculations, as the particles in hemispheres of flavor tagged light quark (uds) events. We present the distributions of rapidity, scaled energy, the logarithm of the momentum, and transverse momentum with respect to the jet axes, for charged particles in these gluon and quark jets. We also examine the charged particle multiplicity distributions of the jets in restricted intervals of rapidity. For soft particles at large transverse momentum, we observe the charged particle multiplicity ratio of gluon to quark jets to be 2.29 +- 0.09 +- 0.15 in agreement with the prediction that this ratio should ap...

Numerical investigation of flow past a row of rectangular rods

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S.Ul. Islam

2016-09-01

Full Text Available A numerical study of uniform flow past a row of rectangular rods with aspect ratio defined as R = width/height = 0.5 is performed using the Lattice Boltzmann method. For this study the Reynolds number (Re is fixed at 150, while spacings between the rods (g are taken in the range from 1 to 6. Depending on g, the flow is classified into four patterns: flip-flopping, nearly unsteady-inphase, modulated inphase-antiphase non-synchronized and synchronized. Sudden jumps in physical parameters were observed, attaining either maximum or minimum values, with the change in flow patterns. The mean drag coefficient (Cdmean of middle rod is higher than the second and fourth rod for flip-flopping pattern while in case of nearly unsteady-inphase the middle rod attains minimum drag coefficient. It is also found that the Strouhal number (St of first, second and fifth rod decreases as g increases while that of other two have mixed trend. The results further show that there exist secondary interaction frequencies together with primary vortex shedding frequency due to jet in the gap between rods for 1 ⩽ g ⩽ 3. For the average values of Cdmean and St, an empirical relation is also given as a function of gap spacing. This relation shows that the average values of Cdmean and St approach to those of single rectangular rod with increment in g.

Heat transfer augmentation in rectangular micro channel covered with vertically aligned carbon nanotubes

NARCIS (Netherlands)

Taha, T.J.; Lefferts, Leonardus; van der Meer, Theodorus H.

2016-01-01

An experimental heat transfer investigation was carried out to examine the influence of carbon nanotubes (CNTs) layer deposits on the convective heat transfer performance inside rectangular microchannels. Successful synthesis of vertically aligned CNTs was achieved using a catalytic vapor deposition

Experimental observations and modelling of thermal history within a steel plate during water jet impingement

International Nuclear Information System (INIS)

Liu, Z.D.; Fraser, D.; Samarasekera, I.V.; Lockhart, G.T.

2002-01-01

In order to investigate heat transfer of steel plates under a water jet impingement and to further simulate runout table operation in a hot strip mill, a full-scale pilot runout table facility was designed and constructed at the University of British Columbia (UBC). This paper describes the experimental details, data acquisition and data handling techniques for steel plates during water jet impingement by one circular water jet from an industrial header. Recorded visual observations at the impinging surface were obtained. The effects of cooling water temperature and impingement velocity on the heat transfer from a steel plate were studied. A two-dimensional finite element method-based transient inverse heat conduction model was developed. With the help of the model, heat fluxes and heat transfer coefficients along the impinging surface under various cooling conditions were calculated. The microstructural evolution of the steel plate was also investigated for the varying cooling conditions. Samples were obtained from each plate, polished, etched and then photographed. (author)

A study of the condensation of a high-velocity vapor jet on a coflowing turbulent liquid jet

Science.gov (United States)

Ovsiannikov, V. A.; Levin, A. A.

A method for the experimental determination of the local value of the heat transfer coefficient under conditions of jet condensation is proposed which employs a heat balance expression in differential form. The method is used in an experimental study of the heat transfer characteristics of the condensation of a high-velocity coaxial jet of a slightly superheated (3 percent) steam on a coflowing cylindrical turbulent water jet. In the experiment, the relative velocities reach hundreds of m/s; the temperature nonequilibrium of the phases is high, as is the steam flow mass density during the initial contact; heat transfer between the phases is significant. The results can be used as the basis for determining experimental criterial dependences for jet condensation.

Deformations of free jets

Science.gov (United States)

Paruchuri, Srinivas

This thesis studies three different problems. First we demonstrate that a flowing liquid jet can be controllably split into two separate subfilaments through the applications of a sufficiently strong tangential stress to the surface of the jet. In contrast, normal stresses can never split a liquid jet. We apply these results to observations of uncontrolled splitting of jets in electric fields. The experimental realization of controllable jet splitting would provide an entirely novel route for producing small polymeric fibers. In the second chapter we present an analytical model for the bending of liquid jets and sheets from temperature gradients, as recently observed by Chwalek et al. [Phys. Fluids, 14, L37 (2002)]. The bending arises from a local couple caused by Marangoni forces. The dependence of the bending angle on experimental parameters is presented, in qualitative agreement with reported experiments. The methodology gives a simple framework for understanding the mechanisms for jet and sheet bending. In chapter 4 we address the discrepancy between hydrodynamic theory of liquid jets, and the snap-off of narrow liquid jets observed in molecular dynamics (MD) simulations [23]. This has been previously attributed to the significant role of thermal fluctuations in nanofluidic systems. We argue that hydrodynamic description of such systems should include corrections to the Laplace pressure which result from the failure of the sharp interface assumption when the jet diameter becomes small enough. We show that this effect can in principle give rise to jet shapes similar to those observed in MD simulations, even when thermal fluctuations are completely neglected. Finally we summarize an algorithm developed to simulate droplet impact on a smooth surface.

Realization of Rectangular Artificial Spin Ice and Direct Observation of High Energy Topology.

Science.gov (United States)

Ribeiro, I R B; Nascimento, F S; Ferreira, S O; Moura-Melo, W A; Costa, C A R; Borme, J; Freitas, P P; Wysin, G M; de Araujo, C I L; Pereira, A R

2017-10-25

In this work, we have constructed and experimentally investigated frustrated arrays of dipoles forming two-dimensional artificial spin ices with different lattice parameters (rectangular arrays with horizontal and vertical lattice spacings denoted by a and b respectively). Arrays with three different aspect ratios γ = a/b = [Formula: see text], [Formula: see text] and [Formula: see text] are studied. Theoretical calculations of low-energy demagnetized configurations for these same parameters are also presented. Experimental data for demagnetized samples confirm most of the theoretical results. However, the highest energy topology (doubly-charged monopoles) does not emerge in our theoretical model, while they are seen in experiments for large enough γ. Our results also insinuate that the string tension connecting two magnetic monopoles in a pair vanishes in rectangular lattices with a critical ratio γ = γ c  = [Formula: see text], supporting previous theoretical predictions.

Effect of guide wall on jet impingement cooling in blade leading edge channel

International Nuclear Information System (INIS)

Zhao, Qing-Yang; Chung, Heeyoon; Choi, Seok Min; Cho, Hyung Hee

2016-01-01

The characteristics of fluid flow and heat transfer, which are affected by the guide wall in a jet impinged leading edge channel, have been investigated numerically using three-dimensional Reynolds-averaged Navier-Stokes analysis via the shear stress transport turbulence model and gamma theta transitional turbulence model. A constant wall heat flux condition has been applied to the leading edge surface. The jet-to-surface distance is constant, which is three times that of the jet diameter. The arrangement of the guide wall near the jet hole is set as a variable. Results presented in this study include the Nusselt number contour, velocity vector, streamline with velocity, and local Nusselt number distribution along the central line on the leading edge surface. The average Nusselt number and average pressure loss between jet nozzle and channel exit are calculated to assess the thermal performance. The application of the guide wall is aimed at improving heat transfer uniformity on the leading edge surface. Results indicated that the streamwise guide wall ensures the vertical jet impingement flow intensity and prevents the flow after impingement to reflux into jet flow. Thus, a combined rectangular guide wall benefits the average heat transfer, thermal performance and heat transfer distribution uniformity

Effect of rising time of rectangular pulse on inactivation of staphylococcus aureus by pulsed electric field

Science.gov (United States)

Zhang, Ruobing; Liang, Dapeng; Zheng, Nanchen; Xiao, Jianfu; Mo, Mengbin; Li, Jing

2013-03-01

Pulsed electric field (PEF) is a novel non-thermal food processing technology that involves the electric discharge of high voltage short pulses through the food product. In PEF study, rectangular pulses are most commonly used for inactivating microorganisms. However, little information is available on the inactivation effect of rising time of rectangular pulse. In this paper, inactivation effects, electric field strength, treatment time and conductivity on staphylococcus aureus inactivation were investigated when the pulse rising time is reduced from 2.5 μs to 200 ns. Experimental results showed that inactivation effect of PEF increased with electric field strength, solution conductivity and treatment time. Rising time of the rectangular pulse had a significant effect on the inactivation of staphylococcus aureus. Rectangular pulses with a rising time of 200 ns had a better inactivation effect than that with 2 μs. In addition, temperature increase of the solution treated by pulses with 200 ns rising time was lower than that with 2 μs. In order to obtain a given inactivation effect, treatment time required for the rectangular pulse with 200 ns rise time was shorter than that with 2 μs.

Effect of rising time of rectangular pulse on inactivation of staphylococcus aureus by pulsed electric field

International Nuclear Information System (INIS)

Zhang, Ruobing; Liang, Dapeng; Xiao, Jianfu; Mo, Mengbin; Li, Jing; Zheng, Nanchen

2013-01-01

Pulsed electric field (PEF) is a novel non-thermal food processing technology that involves the electric discharge of high voltage short pulses through the food product. In PEF study, rectangular pulses are most commonly used for inactivating microorganisms. However, little information is available on the inactivation effect of rising time of rectangular pulse. In this paper, inactivation effects, electric field strength, treatment time and conductivity on staphylococcus aureus inactivation were investigated when the pulse rising time is reduced from 2.5 μs to 200 ns. Experimental results showed that inactivation effect of PEF increased with electric field strength, solution conductivity and treatment time. Rising time of the rectangular pulse had a significant effect on the inactivation of staphylococcus aureus. Rectangular pulses with a rising time of 200 ns had a better inactivation effect than that with 2 μs. In addition, temperature increase of the solution treated by pulses with 200 ns rising time was lower than that with 2 μs. In order to obtain a given inactivation effect, treatment time required for the rectangular pulse with 200 ns rise time was shorter than that with 2 μs.

Numerical Predictions of Enhanced Impingement Jet Cooling with Ribs and Pins in Co-Flow and Cross-Flow Configurations

Directory of Open Access Journals (Sweden)

A. M. El-Jummah

2017-02-01

Full Text Available Numerical calculations relevant to gas turbine internal wall heat transfer cooling were conducted using conjugate heat transfer (CHT computational Fluid Dynamics (CFD commercial codes. The CHT CFD predictions were carried out for impingement heat transfer with different types of obstacle walls (fins on the target surfaces. A 10 × 10 row of impingement air jet holes (or hole density n of 4306 m-2 was used, which gives ten rows of holes in the cross-flow direction and only one heat transfer enhancement obstacle per impingement jet was investigated. Previously, four different shaped obstacles were investigated experimentally and were used to validate the present predictions. The obstacle walls, which were equally spaced on the centreline between each impingement jet are of the co-flow and cross-flow configurations. The impingement jet pitch X to diameter D, X/D and gap Z to diameter, Z/D ratios were kept constant at 4.66 and 3.06 for X, Z and D of 15.24, 10.00 and 3.27 mm, respectively. The obstacles investigated were ribs and rectangular pin-fins shapes, using two obstacles height H to diameter, H/D ratio of 1.38 and 2.45. Computations were carried out for three different mass flux G of 1.08, 1.48 and 1.94 kg/sm2. Relative pressure loss ∆P/P and surface average heat transfer coefficient (HTC h predictions for the range of G, showed good agreement with the experimental results. The prediction also reveals that obstacles not only increases the turbulent flows, but also takes away most of the cooling heat transfer that produces the regions with highest thermal gradients. It also reduces the impingement gap downstream cross-flow.

Experimental investigation of liquid jet injection into Mach 6 hypersonic crossflow

Energy Technology Data Exchange (ETDEWEB)

Beloki Perurena, J. [von Karman Institute for Fluid Dynamics, Rhode-Saint-Genese (Belgium)]|[RWTH Aachen University, Shock Wave Laboratory, Aachen (Germany); Asma, C.O. [von Karman Institute for Fluid Dynamics, Rhode-Saint-Genese (Belgium)]|[Ghent University, Department of Flow, Heat and Combustion Mechanics, Ghent (Belgium); Theunissen, R. [von Karman Institute for Fluid Dynamics, Rhode-Saint-Genese (Belgium)]|[Delft University of Technology, Faculty of Aerospace Engineering, Delft (Netherlands); Chazot, O. [von Karman Institute for Fluid Dynamics, Rhode-Saint-Genese (Belgium)

2009-03-15

The injection of a liquid jet into a crossing Mach 6 air flow is investigated. Experiments were conducted on a sharp leading edge flat plate with flush mounted injectors. Water jets were introduced through different nozzle shapes at relevant jet-to-air momentum-flux ratios. Sufficient temporal resolution to capture small scale effects was obtained by high-speed recording, while directional illumination allowed variation in field of view. Shock pattern and flow topology were visualized by Schlieren-technique. Correlations are proposed on relating water jet penetration height and lateral extension with the injection ratio and orifice diameter for circular injector jets. Penetration height and lateral extension are compared for different injector shapes at relevant jet-to-air momentum-flux ratios showing that penetration height and lateral extension decrease and increase, respectively, with injector's aspect ratio. Probability density function analysis has shown that the mixing of the jet with the crossflow is completed at a distance of x/d{sub j}{proportional_to} 40, independent of the momentum-flux ratio. Mean velocity profiles related with the liquid jet have been extracted by means of an ensemble correlation PIV algorithm. Finally, frequency analyses of the jet breakup and fluctuating shock pattern are performed using a fast Fourier algorithm and characteristic Strouhal numbers of St=0.18 for the liquid jet breakup and of St=0.011 for the separation shock fluctuation are obtained. (orig.)

Applicability of electrical resistance tomography to rectangular vessels

International Nuclear Information System (INIS)

Ichijo, Noriaki; Matsuno, Shinsuke; Tokura, Susumu; Tochigi, Yoshikatsu; Misumi, Ryuta; Nishi, Kazuhiko; Kaminoyama, Meguru

2012-01-01

To ensure a stable operation of Joule-heated glass melters, it is necessary to observe the distribution of platinum group metal particles (noble metals) in molten glass. Electrical resistance tomography (ERT) has a potential to visualize the inside of the melter section because it can be applied at severe conditions such as high temperature and radioactive fields. Due to designing limitations, it is difficult to install electrodes on the wall of the glass melter. In addition, ERT is hardly applied to a rectangular section. To solve these problems, numerical and experimental studies have been implemented. To apply the ERT method, 8 electrodes are inserted from the top of the melter and set near the bottom to visualize the accumulation of noble metals on the bottom area. As a result of the numerical simulation and the experiment, it was clarified that the ERT can be applied to the rectangular vessel by inserting electrodes from the top of the vessel and has a potential to observe the accumulation of noble metals. (author)

Experimental and numerical investigation of the flow field in the gradual transition of rectangular to trapezoidal open channels

Directory of Open Access Journals (Sweden)

Adel Asnaashari

2016-01-01

Full Text Available Transitions are structures that can change geometry and flow velocity through varying the cross-sections of their channels. Under subcritical flow and steady flow conditions, it is necessary to reduce the flow velocity gradually due to increasing water pressure and adverse pressure gradients. Due to the separation of flow and subsequent eddy formation, a significant energy loss is incurred along the transition. This study presents the results of experimental investigations of the subcritical flow along the expansive transition of rectangular to trapezoidal channels. A numerical simulation was developed using a finite volume of fluid (VOF method with a Reynolds stress turbulence model. Water surface profiles and velocity distributions of flow through the transition were measured experimentally and compared with the numerical results. A good agreement between the experimental and numerical model results showed that the Reynolds model and VOF method are capable of simulating the hydraulic flow in open channel transitions. Also, the efficiency of the transition and coefficient of energy head loss were calculated. The results show that with an increasing upstream Froude number, the efficiency of the transition and coefficient of energy head loss decrease and increase, respectively. The results also show the ability of numerical simulation to simulate the flow separation zones and secondary current along the transition for different inlet discharges.

Square and Rectangular Arrays from Directed Assembly of Sphere-forming Diblock Copolymers in Thin Films

Science.gov (United States)

Ji, Shengxiang; Nagpal, Umang; Liao, Wen; de Pablo, Juan; Nealey, Paul

2010-03-01

Patterns of square and rectangular arrays with nanoscale dimensions are scientifically and technologically important. Fabrication of square array patterns in thin films has been demonstrated by directed assembly of cylinder-forming diblock copolymers on chemically patterned substrates, supramolecular assembly of diblock copolymers, and self-assembly of triblock terpolymers. However, a macroscopic area of square array patterns with long-range order has not been achieved, and the fabrication of rectangular arrays has not been reported so far. Here we report a facile approach for fabricating patterns of square and rectangular arrays by directing the assembly of sphere-forming diblock copolymers on chemically patterned substrates. On stripe patterns, a square arrangement of half spheres, corresponding to the (100) plane of the body-centred cubic (BCC) lattice, formed on film surfaces. When the underlying pattern periods mismatched with the copolymer period, the square pattern could be stretched (up to ˜60%) or compressed (˜15%) to form rectangular arrays. Monte Carlo simulations have been further used to verify the experimental results and the 3-dimensional arrangements of spheres.

Experimental studies on improving the performance of electrochemical machining of high carbon, high chromium die steel using jet patterns

Directory of Open Access Journals (Sweden)

V. Sathiyamoorthy

2014-03-01

Full Text Available Electrochemical machining (ECM is a non-traditional process used mainly to cut hard or difficult-to-cut metals, where the application of a more traditional process is not convenient. Stiff market competition and ever-growing demand for better, durable and reliable products has brought about a material revolution, which has greatly expanded the families of difficult-to-machine materials namely highcarbon,high-chromium die steel; stainless steel and superalloys. This investigation attempts to analyze the effect of electrolyte distribution on material removal rate (MRR and surface roughness (SR on electrochemical machining of high-carbon, high-chromium die steel using NaCl aqueous solution. Three electrolyte jet patterns namely straight jet in circular, inclined jet in circular and straight jet in spiral were used for this experimentation. The results reveal that electrolyte distribution significantly improves the performance of ECM and the straight jet in spiral pattern performs satisfactorily in obtaining better MRR and surface roughness.

Influence of the column rectangularity index and of the boundary conditions in the punching resistance of slab-column connections

Directory of Open Access Journals (Sweden)

O. S. PAIVA

Full Text Available Experimental evidence indicates that both the column rectangularity index and the boundary conditions of the connection may affect the ultimate punching resistance. This paper presents general aspects of these topics and, through the analysis of experimental results of tests on 131 slabs, evaluates the accuracy and suitability of recommendations presented by ABNT NBR 6118, Eurocode 2, ACI 318 and fib Model Code 2010. Experimental results showed that the security level of normative estimates trend to reduce as the column rectangularity increases, and in some cases, the punching resistance was overestimated. Finally, adjustments are suggested in equations presented by NBR 6118 and MC2010 in order to eliminate this trend of unsafe results.

Numerical simulation of air distribution in a room with a sidewall jet under benchmark test conditions

Science.gov (United States)

Zasimova, Marina; Ivanov, Nikolay

2018-05-01

The goal of the study is to validate Large Eddy Simulation (LES) data on mixing ventilation in an isothermal room at conditions of benchmark experiments by Hurnik et al. (2015). The focus is on the accuracy of the mean and rms velocity fields prediction in the quasi-free jet zone of the room with 3D jet supplied from a sidewall rectangular diffuser. Calculations were carried out using the ANSYS Fluent 16.2 software with an algebraic wall-modeled LES subgrid-scale model. CFD results on the mean velocity vector are compared with the Laser Doppler Anemometry data. The difference between the mean velocity vector and the mean air speed in the jet zone, both LES-computed, is presented and discussed.

Experimental and numerical study of a premixed flame stabilized by a rectangular section cylinder

Energy Technology Data Exchange (ETDEWEB)

Bailly, P.; Garreton, D. [Electricite de France (EDF), 92 - Clamart (France); Bruel, P.; Champion, M. et al. [Ecole Nationale Superieure de Mecanique et d`Aerotechnique (ENSMA), 86 - Poitiers (France)

1996-12-31

A numerical and experimental study of a turbulent reactive zone stabilized by a rectangular cross-section cylinder positioned in a fully developed turbulent channel flow of a propane-air mixture is presented. Such a flow geometry has been chosen because it features most of the phenomena (recirculation zones, flame stabilization, wall-flame interactions) present in systems of practical interest. The flow is experimentally investigated with a 2-D laser Doppler velocimeter and thin compensated thermocouples. The modelling of the reactive flow is based on a modified Bray-Moss-Libby combustion model associated with a Reynolds-Stress turbulence model. The resulting set of equations is solved by a finite difference Navier-Stokes code on a rectilinear mesh. The comparison between numerical nd experimental results shows that the use of a full second-order model with dedicated equations for both the Reynolds stresses and the scalar turbulent flux does not lead to a significant improvement of the numerical results. Indeed, although the longitudinal scalar turbulent flux exhibits a non-gradient behaviour, the evolution of the mean progress variable introduced by the Bray-Moss-Libby model appears to be mainly controlled by the transverse scalar gradient which follows in all cases a gradient like behaviour. Additional measurements and calculations are required to precise the exact range of mass flow rate, equivalence ratio and obstacle bluffness over which such a tendency can be observed. Nevertheless, the tentative conclusion of this study is that, as soon as a refinement of the modelling of reactive flows in combustors which involve flameholders similar to the one investigated in this study is needed, the use of a Reynolds-Stress model should be the first necessary step. Then, depending on the exact nature of the flow geometry, a second phase should consist in evaluating the need for the use of a full second order model like the one presented in this study. (authors) 25 refs.

Experimental study of natural circulation flow instability in rectangular channels

Energy Technology Data Exchange (ETDEWEB)

Zhou, Tao; Qi, Shi; Song, Mingqiang [North China Electric Power Univ., Beijing (China). School of Nuclear Science and Engineering; Passive Nuclear Safety Technology, Beijing (China). Beijing Key Lab.; Xiao, Zejun [Nuclear, Reactor Thermal Hydraulics Technology, Chengdu (China). CNNC Key Lab.

2017-05-15

Experiments of natural circulation flow instability were conducted in rectangular channels with 5 mm and 10 mm wide gaps. Results for different heating powers were obtained. The results showed that the flow will tend to be instable with the growing of heating power. The oscillation period of pressure D-value and volume flow are the same, but their phase positions are opposite. They both can be described by trigonometric functions. The existence of edge position and secondary flow will strengthen the disturbance of fluid flow in rectangle channels, which contributes to heat transfer. The disturbance of bubble and fluid will be strengthened, especially in the saturated boiling section, which make it possible for the mixing flow. The results also showed that the resistance in 5 mm channel is bigger than that in 10 mm channel, it is less likely to form stable natural circulation in the subcooled region.

Impact of jet veto resummation on slepton searches

International Nuclear Information System (INIS)

Tackmann, Frank J.; Waalewijn, Wouter J.; Nikhef, Amsterdam; Zeune, Lisa

2016-03-01

Several searches for new physics at the LHC require a fixed number of signal jets, vetoing events with additional jets from QCD radiation. As the probed scale of new physics gets much larger than the jet-veto scale, such jet vetoes strongly impact the QCD perturbative series, causing nontrivial theoretical uncertainties. We consider slepton pair production with 0 signal jets, for which we perform the resummation of jet-veto logarithms and study its impact. Currently, the experimental exclusion limits take the jet-veto cut into account by extrapolating to the inclusive cross section using parton shower Monte Carlos. Our results indicate that the associated theoretical uncertainties can be large, and when taken into account have a sizeable impact already on present exclusion limits. This is improved by performing the resummation to higher order, which allows us to obtain accurate predictions even for high slepton masses. For the interpretation of the experimental results to benefit from improved theory predictions, it would be useful for the experimental analyses to also provide limits on the unfolded visible 0-jet cross section.

Effect of outer stagnation pressure on jet structure in supersonic coaxial jet

International Nuclear Information System (INIS)

Kim, Myoung Jong; Woo, Sang Woo; Lee, Byeong Eun; Kwon, Soon Bum

2001-01-01

The characteristics of dual coaxial jet which composed of inner supersonic nozzle of 26500 in constant expansion rate with 1.91 design Mach number and outer converging one with 40 .deg. C converging angle with the variation of outer nozzle stagnation pressure are experimentally investigated in this paper. In which the stagnation pressure for the inner supersonic nozzle is 750kPa thus, the inner jet leaving the nozzle is slightly underexpanded. The plenum pressure of outer nozzle are varied from 200 to 600kPa. Flow visualizations by shadowgraph method, impact pressure and centerline static pressure measurements of dual coaxial jet are presented. The results show that the presence of outer jet affects significantly the structures and pressure distributions of inner jet. And outer jet causes Mach disk which does not appear for the case of single jet stream. As the stagnation pressure of outer jet increases, impact pressure undulation is severe, but the average impact pressure keeps high far downstream

Properties of gluon jets

International Nuclear Information System (INIS)

Sugano, K.

1988-01-01

The properties of gluon jets are reviewed from an experimental point of view. The measured characteristics are compared to theoretical expectations. Although neither data nor models for the gluon jets are in the mature stage, there are remarkable agreements and also intriguing disagreements between experiment and theory. Since much interesting data have begun to emerge from various experiments and the properties of gluon jets are deeply rooted in the basic structure of non-Abelian gauge theory, the study of gluon jets casts further light on understanding of QCD. The future prospects are discussed

Hadronic jets an introduction

CERN Document Server

Banfi, Andrea

2016-01-01

Jet physics is an incredibly rich subject detailing the narrow cone of hadrons and other particles produced by the hadronization of a quark or gluon in a particle physics or heavy ion experiment. This book is a general overview of jet physics for scientists not directly involved in the field. It presents the basic experimental and theoretical problems arising when dealing with jets, and describing the solutions proposed in recent years.

Characteristics of compressed natural gas jet and jet-wall impingement using the Schlieren imaging technique

International Nuclear Information System (INIS)

Ismael, M A; Heikal, M R; Baharom, M B

2013-01-01

An experimental study was performed to investigate the compressed natural gas jet characteristics and jet-wall impingement using the Schlieren imaging technique and image processing. An injector driver was used to drive the natural gas injector and synchronized with camera triggering. A constant-volume optical chamber was designed to facilitate maximum optical access for the study of the jet macroscopic characteristics and jet-wall impingement at different injection pressures and injectors-wall distances. Measurement of the jet tip penetration and cone angle at different conditions are presented in this paper together with temporal presentation of the jet radial travel along the wall.

Experimental Investigation on Frequency Characteristics of Plasma Synthetic Jets

NARCIS (Netherlands)

Zong, H.; Kotsonis, M.

2017-01-01

The performance of a two–electrode plasma synthetic jet actuator (PSJA) is investigated for a wide range of dimensionless actuation frequencies (f*) using high-speed phase-locked Particle Imaging Velocimetry (PIV) measurements. The jet-induced velocity fields in the

Experimental properties of gluon and quark jets from a point source

International Nuclear Information System (INIS)

Abbiendi, G.; Ackerstaff, K.; Alexander, G.

1999-01-01

Gluon jets are identified in hadronic Z 0 decays as all the particles in a hemisphere opposite to a hemisphere containing two tagged quark jets. Gluon jets defined in this manner are equivalent to gluon jets produced from a color singlet point source and thus correspond to the definition employed for most theoretical calculations. In a separate stage of the analysis, we select quark jets in a manner to correspond to calculations, as the particles in hemispheres of flavor tagged light quark (uds) events. We present the distributions of rapidity, scaled energy, the logarithm of the momentum, and transverse momentum with respect to the jet axes, for charged particles in these gluon and quark jets. We also examine the charged particle multiplicity distributions of the jets in restricted intervals of rapidity. For soft particles at large p T , we observe the charged particle multiplicity ratio of gluon to quark jets to be 2.29±0.09(stat.)±0.15(syst.), in agreement with the prediction that this ratio should approximately equal the ratio of QCD color factors, C A /C F =2.25. The intervals used to define soft particles and large p T for this result, p T < 3.0 GeV/c, are motivated by the predictions of the Herwig Monte Carlo multihadronic event generator. Additionally, our gluon jet data allow a sensitive test of the phenomenon of non-leading QCD terms known as color reconnection. We test the model of color reconnection implemented in the Ariadne Monte Carlo multihadronic event generator and find it to be disfavored by our data. (orig.)

Predictions for Boson-Jet Observables and Fragmentation Function Ratios from a Hybrid Strong/Weak Coupling Model for Jet Quenching

CERN Document Server

Casalderrey-Solana, Jorge; Milhano, José Guilherme; Pablos, Daniel; Rajagopal, Krishna

2016-01-01

We have previously introduced a hybrid strong/weak coupling model for jet quenching in heavy ion collisions that describes the production and fragmentation of jets at weak coupling, using PYTHIA, and describes the rate at which each parton in the jet shower loses energy as it propagates through the strongly coupled plasma, dE/dx, using an expression computed holographically at strong coupling. The model has a single free parameter that we fit to a single experimental measurement. We then confront our model with experimental data on many other jet observables, focusing here on boson-jet observables, finding that it provides a good description of present jet data. Next, we provide the predictions of our hybrid model for many measurements to come, including those for inclusive jet, dijet, photon-jet and Z-jet observables in heavy ion collisions with energy $\\sqrt{s}=5.02$ ATeV coming soon at the LHC. As the statistical uncertainties on near-future measurements of photon-jet observables are expected to be much sm...

Experimental investigation of effect of flow attack angle on thermohydraulic performance of air flow in a rectangular channel with discrete V-pattern baffle on the heated plate

Directory of Open Access Journals (Sweden)

Raj Kumar

2016-05-01

Full Text Available In this work, the effect of angle of attack ( α a of the discrete V-pattern baffle on thermohydraulic performance of rectangular channel has been studied experimentally. The baffle wall was constantly heated and the other three walls of the channel were kept insulated. The experimentations were conducted to collect the data on Nusselt number ( N u b and friction factor ( f b by varying the Reynolds number (Re = 3000–21,000 and angle of attack ( α a from 30° to 70°, for the kept values of relative baffle height ( H b / H = 0 . 50 , relative pitch ratio ( P b / H = 1 . 0 , relative discrete width ( g w / H b = 1 . 5 and relative discrete distance ( D d / L v = 0 . 67 . As compared to the smooth wall, the V-pattern baffle roughened channel enhances the Nusselt number ( N u b and friction factor ( f b by 4.2 and 5.9 times, respectively. The present discrete V-pattern baffle shapes with angle of attack ( α a of 60° equivalent to flow Reynolds number of 3000 yields the greatest thermohydraulic performance. Discrete V-pattern baffle has improved thermal performance as compared to other baffle shapes’ rectangular channel.

Obtaining S values for rectangular--solid tumors inside rectangular--solid host organs

International Nuclear Information System (INIS)

Stinchcomb, T.G.; Durham, J.S.; Fisher, D.R.

1991-01-01

A method is described for obtaining S values between a tumor and its host organ for use with the MIRD formalism. It applies the point-source specific absorbed fractions for an infinite water medium, tabulated by Berger, to a rectangular solid of arbitrary dimensions which contains a rectangular tumor of arbitrary dimensions. Contributions from pairs of source and target volume elements are summed for the S values between the tumor and itself, between the remaining healthy host organ and itself, and between the tumor and the remaining healthy host organ, with the reciprocity theorem assumed for the last. This method labeled MTUMOR, is interfaced with the widely used MIRDOSE program which incorporates the MIRD formalism. An example is calculated

Production of radiatively cooled hypersonic plasma jets and links to astrophysical jets

International Nuclear Information System (INIS)

Lebedev, S V; Ciardi, A; Ampleford, D J; Bland, S N; Bott, S C; Chittenden, J P; Hall, G N; Rapley, J; Jennings, C; Sherlock, M; Frank, A; Blackman, E G

2005-01-01

We present results of high energy density laboratory experiments on the production of supersonic radiatively cooled plasma jets with dimensionless parameters (Mach number ∼30, cooling parameter ∼1 and density contrast ρ j /ρ a ∼ 10) similar to those in young stellar objects jets. The jets are produced using two modifications of wire array Z-pinch driven by 1 MA, 250 ns current pulse of MAGPIE facility at Imperial College, London. In the first set of experiments the produced jets are purely hydrodynamic and are used to study deflection of the jets by the plasma cross-wind, including the structure of internal oblique shocks in the jets. In the second configuration the jets are driven by the pressure of the toroidal magnetic field and this configuration is relevant to the astrophysical models of jet launching mechanisms. Modifications of the experimental configuration allowing the addition of the poloidal magnetic field and angular momentum to the jets are also discussed. We also present three-dimensional resistive magneto-hydrodynamic simulations of the experiments and discuss the scaling of the experiments to the astrophysical systems

Turbulent Buoyant Jets in Flowing Ambients

DEFF Research Database (Denmark)

Chen, Hai-Bo; Larsen, Torben; Petersen, Ole

1991-01-01

The mean behaviour of horizontal turbulent buoyant jets in co-flowing currents is investigated experimentally and numerically, in terms of jet trajectory, dilution and centerline density deficit and velocity decay. It is demonstrated in the paper that the laboratory data on the jet trajectory and...

Experimental and numerical study on single-phase flow characteristics of natural circulation system with heated narrow rectangular channel under rolling motion condition

International Nuclear Information System (INIS)

Yu, Shengzhi; Wang, Jianjun; Yan, Ming; Yan, Changqi; Cao, Xiaxin

2017-01-01

Highlights: • The phasic difference between flow rate and frictional pressure drop is negligible. • Effect mechanism of rolling motion on flow behaviors of NC is interpreted. • The startup model is proposed and verified. • Steady-state correlations are feasible to predict transient resistance. • The in-house code can simulate instantaneous flow behaviors of NC correctly. - Abstract: Effects of rolling motion on flow characteristics in a natural circulation system were investigated experimentally and numerically. The numerical results from validated code were mainly used to provide detailed information for the discussion and analysis of experimental results. The results indicate that under rolling motion condition, the phasic difference between flow rate and frictional pressure drop of narrow rectangular channel is negligible. Angular acceleration is the eigenvalue for the effects of rolling motion on flow rate under single-phase natural circulation condition. When angular acceleration is approximately equal, even though either the angle or the period of rolling motion is different, peak, trough and time-averaged values of flow rate are approximately equal. Under rolling motion and single-phase natural circulation conditions, the phenomenon that dimensionless time-averaged mass flow rate is smaller than that under steady state condition is controlled by the nonlinear relationship between mass flow rate and the resistance of loop. The factor also causes the result that the absolute difference of dimensionless flow rate between peak and steady state is smaller than that between trough and steady state. The startup model which is proposed in present paper can be used to predict the flow characteristics of single-phase natural circulation system at startup stage of rolling motion favorably. The self-developed code can simulate instantaneous flow characteristics of single-phase natural circulation system under rolling motion and steady state conditions

Best connected rectangular arrangements

Directory of Open Access Journals (Sweden)

Krishnendra Shekhawat

2016-03-01

Full Text Available It can be found quite often in the literature that many well-known architects have employed either the golden rectangle or the Fibonacci rectangle in their works. On contrary, it is rare to find any specific reason for using them so often. Recently, Shekhawat (2015 proved that the golden rectangle and the Fibonacci rectangle are one of the best connected rectangular arrangements and this may be one of the reasons for their high presence in architectural designs. In this work we present an algorithm that generates n-4 best connected rectangular arrangements so that the proposed solutions can be further used by architects for their designs.

Time-frequency analysis of submerged synthetic jet

Science.gov (United States)

Kumar, Abhay; Saha, Arun K.; Panigrahi, P. K.

2017-12-01

The coherent structures transport the finite body of fluid mass through rolling which plays an important role in heat transfer, boundary layer control, mixing, cooling, propulsion and other engineering applications. A synthetic jet in the form of a train of vortex rings having coherent structures of different length scales is expected to be useful in these applications. The propagation and sustainability of these coherent structures (vortex rings) in downstream direction characterize the performance of synthetic jet. In the present study, the velocity signal acquired using the S-type hot-film probe along the synthetic jet centerline has been taken for the spectral analysis. One circular and three rectangular orifices of aspect ratio 1, 2 and 4 actuating at 1, 6 and 18 Hz frequency have been used for creating different synthetic jets. The laser induced fluorescence images are used to study the flow structures qualitatively and help in explaining the velocity signal for detection of coherent structures. The study depicts four regions as vortex rollup and suction region (X/D h ≤ 3), steadily translating region (X/D h ≤ 3-8), vortex breakup region (X/Dh ≤ 4-8) and dissipation of small-scale vortices (X/D h ≤ 8-15). The presence of coherent structures localized in physical and temporal domain is analyzed for the characterization of synthetic jet. Due to pulsatile nature of synthetic jet, analysis of velocity time trace or signal in time, frequency and combined time-frequency domain assist in characterizing the signatures of coherent structures. It has been observed that the maximum energy is in the first harmonic of actuation frequency, which decreases slowly in downstream direction at 6 Hz compared to 1 and 18 Hz of actuation.

An experimental study of solar desalination using free jets and an auxiliary hot air stream

Science.gov (United States)

Eid, Eldesouki I.; Khalaf-Allah, Reda A.; Dahab, Mohamed A.

2018-04-01

An experimental study for a solar desalination system based on jet-humidification with an auxiliary perpendicular hot air stream was carried out at Suez city, Egypt 29.9668°N, 32.5498°E. The tests were done from May to October 2016. The effects of nozzles situations and nozzle diameter with and without hot air stream on fresh water productivity were monitored. The results show that; the lateral and downward jets from narrow nozzles have more productivities than other situations. The hot air stream has to be adapted at a certain flow rate to get high values of productivity. The system productivity is (5.6 L/m 2 ), the estimated cost is (0.030063 / L) and the efficiency is 32.8%.

An experimental and numerical study of confined non-reacting and reacting turbulent jets to facilitate homogeneous combustion in industrial furnaces

Science.gov (United States)

Lee, Insu

Confined non-reacting turbulent jets are ideal for recirculating the hot flue gas back into the furnace from an external exhaust duct. Such jets are also used inside the furnace to internally entrain and recirculate the hot flue gas to preheat and dilute the reactants. Both internal and external implementation of confined turbulent jets increase the furnace thermal efficiency. For external implementation, depending on the circumstances, the exhaust gas flow may be co- or counter-flow relative to the jet flow. Inside the furnaces, fuel and air jets are injected separately. To create a condition which can facilitate near homogeneous combustion, these jets have to first mix with the burned gas inside the furnace and simultaneously being heated and diluted prior to combustion. Clearly, the combustion pattern and emissions from reacting confined turbulent jets are affected by jet interactions, mixing and entrainment of hot flue gas. In this work, the flow and mixing characteristics of a non-reacting and reacting confined turbulent jet are investigated experimentally and numerically. This work consists of two parts: (i) A study of flow and mixing characteristics of non-reacting confined turbulent jets with co- or counter-flowing exhaust/flue gas. Here the axial and radial distributions of temperature, velocity and NO concentration (used as a tracer gas) were measured. FLUENT was used to numerically simulate the experimental results. This work provides the basic understanding of the flow and mixing characteristics of confined turbulent jets and develops some design considerations for recirculating flue gas back into the furnace as expressed by the recirculation zone and the stagnation locations. (ii) Numerical calculations of near homogeneous combustion are performed for the existing furnace. The exact geometry of the furnace in the lab is used and the real dimensional boundary conditions are considered. The parameters such as air nozzle diameter (dair), fuel nozzle

Experimental investigation of the two-phase flow in a short horizontal microchannel with the height of 50 μm and width of 20 mm

Directory of Open Access Journals (Sweden)

Ronshin Fedor

2017-01-01

Full Text Available The two-phase flow has been studied experimentally in a short horizontal microchannel with the height of 50 μm and width of 20 mm. The following regimes of two-phase flows have been registered: jet, bubble, stratified, annular, and churn. The regime map of two-phase flow has been plotted. This map has been compared with the regime map plotted for the channels of larger cross-section; it is shown that the height and width of a rectangular channel has a significant effect on the boundaries between flow regimes.

Springback Mechanism Analysis and Experiments on Robotic Bending of Rectangular Orthodontic Archwire

Science.gov (United States)

Jiang, Jin-Gang; Han, Ying-Shuai; Zhang, Yong-De; Liu, Yan-Jv; Wang, Zhao; Liu, Yi

2017-11-01

Fixed-appliance technology is the most common and effective malocclusion orthodontic treatment method, and its key step is the bending of orthodontic archwire. The springback of archwire did not consider the movement of the stress-strain-neutral layer. To solve this problem, a springback calculation model for rectangular orthodontic archwire is proposed. A bending springback experiment is conducted using an orthodontic archwire bending springback measurement device. The springback experimental results show that the theoretical calculation results using the proposed model coincide better with the experimental testing results than when movement of the stress-strain-neutral layer was not considered. A bending experiment with rectangular orthodontic archwire is conducted using a robotic orthodontic archwire bending system. The patient expriment result show that the maximum and minimum error ratios of formed orthodontic archwire parameters are 22.46% and 10.23% without considering springback and are decreased to 11.35% and 6.13% using the proposed model. The proposed springback calculation model, which considers the movement of the stress-strain-neutral layer, greatly improves the orthodontic archwire bending precision.

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.

Mapping from rectangular to harmonic representation

International Nuclear Information System (INIS)

Schneider, W.; Bateman, G.

1986-08-01

An algorithm is developed to determine the Fourier harmonics representing the level contours of a scalar function given on a rectangular grid. This method is applied to the problem of computing the flux coordinates and flux surface average needed for 1-1/2-D transport codes and MHD stability codes from an equilibrium flux function given on a rectangular grid

Rectangular Gusset Plate Behaviour in Cold-Formed I-Type Steel Connections

Directory of Open Access Journals (Sweden)

Bučmys Ž.

2017-06-01

Full Text Available Cold-formed structure connections utilizing gusset plates are usually semi-rigid. This paper investigates the behaviours of rectangular gusset plates in cold-formed connections of elements whose columns and beams are made with lipped back-to-back C-sections. Methods of calculating strength and stiffness are necessary for such semi-rigid joints. The main task of this paper is to determine a method capable of calculating these characteristics. The proposed analytical method could then be easily adapted to the component method that is described in part 1993-1-8 of the Eurocode. This method allows us to calculate both the strength and stiffness of rectangular gusset plates, assuming that the joint deforms only in plane. This method of design moment resistance calculation was presented taking into account that an entire cross-section shall reach its yield stress. A technique of stiffness calculation was presented investigating the sum of deformations acquired at the bending moment and from shear forces which are transmitted from each beam bolt group. Calculation results according to the suggested method show good agreement of laboratory experimental results of specimens with numerical simulations. Two specimens of beam-to-column connections were tested in the laboratory. Lateral supports were used on the specimens to prevent lateral displacements in order to better investigate the behaviour of the rectangular gusset plate in plane. Experiments were simulated by modelling rectangular gusset plates using standard finite element software ANSYS Workbench 14.0. Three-dimensional solid elements were used for modelling and both geometric and material nonlinear analysis was performed.

Critical heat flux correlation for thin rectangular channels

International Nuclear Information System (INIS)

Tanaka, Futoshi; Mishima, Kaichiro; Hibiki, Takashi

2007-01-01

The effect of heated length on Critical heat flux (CHF) in thin rectangular channels was studied based on CHF data obtained under atmospheric pressure. CHF in small channels has been widely studied in the past decades but most of the studies are related to CHF in round tubes. Although basic mechanisms of burnout in thin rectangular channels are similar to tubes, applicability of CHF correlations for tubes to rectangular channels are questionable since CHF in rectangular channels are affected by the existence of non-heated walls and the non-circular geometry of channel circumference. Several studies of CHF in thin rectangular channels have been reported in relation to thermal hydraulic design of research reactors and neutron source targets and CHF correlations have been proposed, but the studies mostly focus on CHFs under geometrical conditions of the application of interest. In his study, existing CHF data obtained in thin rectangular channels were collected and the effect of heated length on CHF was examined. Existing CHF correlations were verified with positive quality flow CHF data but none of the correlations successfully reproduced the CHF for a wide range of heated length. A new CHF correlation for qualify region applicable to a wide range of heated length was developed based on the collected data. (author)

Experimental study on centerline velocities of a rectangular capture hood under realistic conditions.

Science.gov (United States)

He, Xinjian; Lewis, Braxton V; Guffey, Steven E

2018-02-01

Capture hoods are an important component of a local ventilation system designed to reduce exposures to airborne contaminants. The velocity at any point along the centerline of the hood (V x ) is currently estimated using one of many predictive equations developed since the 1930s. It is unproven that those predictive equations for V x are accurate, despite the prodigious number of studies concerning them. Among other issues, almost all experimental verifications were conducted for conditions that were either unrealistically ideal without competing air currents (e.g., zero cross draft) or were not described. This study measured values of V x along the midline using Particle Image Velocimetry (PIV) at distances of 1-14 inches in front of a rectangular capture hood. The experiments were conducted in a large wind tunnel (9' × 12' × 40', H × W × L) using a heated, breathing, anthropomorphically sized manikin. Three 0 degree draft velocities (V draft = 4, 14, and 50 ft/min) were tested, all directed toward the hood face and the back of the manikin (if present). For each value of V draft , the velocity fields were measured in a factorial design with and without the manikin, and with and without a worktable underneath the hood. An ideal condition was represented by a freestanding hood at the 4 fpm draft. Nonideal conditions included the presence of a worktable or manikin, and the combination of table and manikin. Each condition was tested at the three levels of V draft . The experimental results found significant effects (p < 0.001) for V draft , the presence of the manikin, the presence of the worktable, and all combinations of those factors. The effects of the independent variables were most pronounced at distances greater than 10 in (25.4 cm) from the hood face. It is concluded that none of the previously published models accurately predicted V x under the realistic conditions tested in this study. A satisfactory model will have to include terms for V draft and the

Counter-current gas-liquid two-phase flow in a narrow rectangular channel

International Nuclear Information System (INIS)

Sohn, Byung Hu; Kim, Byong Joo

2000-01-01

A study of counter-current two-phase flow in a narrow rectangular channel has been performed. Two-phase flow patterns and void fractions were experimentally studied in a 760 mm long and 100 mm wide test section with 3.0 mm gap. The resulting data have been compared to previous transition criteria and empirical correlations. The comparison of experimental data to the transition criteria developed by Taitel and Barnea showed good agreement for the bubbly-to-slug transition. For the criteria of Mishima and Ishii to be applicable to the slug to churn transition, a new model seems to be needed for the accurate prediction of the distribution parameter for the counter-current flow in narrow rectangular channels. For the churn-to-annular transition the model of Taitel and Barnea was found to be close to the experimental data. However the model should be improved in conjunction with the channel geometry to accurately predict the counter-current flow limitation and flow transition. It was verified the distribution parameter was well-correlated by the drift-flux model. The distribution parameter for the present study was found to be about 1.2 for all flow regimes except 1.0 for an annular flow. (author)

PIV study of large-scale flow organisation in slot jets

International Nuclear Information System (INIS)

Shestakov, Maxim V.; Dulin, Vladimir M.; Tokarev, Mikhail P.; Sikovsky, Dmitrii Ph.; Markovich, Dmitriy M.

2015-01-01

Highlights: • Volumetric velocity measurements are perfumed by PIV to analyse 3D flow organisation in a slot jet. • Proper orthogonal decomposition is used to extract coherent flow motion. • Movement of quasi-two-dimensional large-scale vortices is associated with jet meandering. • Amplitude of jet meandering is found to be aperiodically modulated. • Secondary longitudinal vortex rolls are important for cross-stream mixing and momentum transfer. - Abstract: The paper reports on particle image velocimetry (PIV) measurements in turbulent slot jets bounded by two solid walls with the separation distance smaller than the jet width (5–40%). In the far-field such jets are known to manifest features of quasi-two dimensional, two component turbulence. Stereoscopic and tomographic PIV systems were used to analyse local flows. Proper orthogonal decomposition (POD) was applied to extract coherent modes of the velocity fluctuations. The measurements were performed both in the initial region close to the nozzle exit and in the far fields of the developed turbulent slot jets for Re ⩾ 10,000. A POD analysis in the initial region indicates a correlation between quasi-2D vortices rolled-up in the shear layer and local flows in cross-stream planes. While the near-field turbulence shows full 3D features, the wall-normal velocity fluctuations day out gradually due to strong wall-damping resulting in an almost two-component turbulence. On the other hand, the longitudinal vortex rolls take over to act as the main agents in wall-normal and spanwise mixing and momentum transfer. The quantitative analysis indicates that the jet meandering amplitude was aperiodically modulated when arrangement of the large-scale quasi-2D vortices changed between asymmetric and symmetric pattern relatively to the jet axis. The paper shows that the dynamics of turbulent slot jets are more complex than those of 2D, plane and rectangular 3D jets. In particular, the detected secondary longitudinal

Rebounding of a shaped-charge jet

Science.gov (United States)

Proskuryakov, E. V.; Sorokin, M. V.; Fomin, V. M.

2007-09-01

The phenomenon of rebounding of a shaped-charge jet from the armour surface with small angles between the jet axis and the target surface is considered. Rebounding angles as a function of jet velocity are obtained in experiments for a copper shaped-charge jet. An engineering calculation technique is developed. The results calculated with the use of this technique are in reasonable agreement with experimental data.

An experimental study of transmission, reflection and scattering of sound in a free jet flight simulation facility and comparison with theory

Science.gov (United States)

Ahuja, K. K.; Tanna, H. K.; Tester, B. J.

1981-01-01

When a free jet (or open jet) is used as a wind tunnel to simulate the effects of flight on model noise sources, it is necessary to calibrate out the effects of the free jet shear layer on the transmitted sound, since the shear layer is absent in the real flight case. In this paper, a theoretical calibration procedure for this purpose is first summarized; following this, the results of an experimental program, designed to test the validity of the various components of the calibration procedure, are described. The experiments are conducted by using a point sound source located at various axial positions within the free jet potential core. By using broadband excitation and cross-correlation methods, the angle changes associated with ray paths across the shear layer are first established. Measurements are then made simultaneously inside and outside the free jet along the proper ray paths to determine the amplitude changes across the shear layer. It is shown that both the angle and amplitude changes can be predicted accurately by theory. It is also found that internal reflection at the shear layer is significant only for large ray angles in the forward quadrant where total internal reflection occurs. Finally, the effects of sound absorption and scattering by the shear layer turbulence are also examined experimentally.

Theoretical and experimental study of a reactive steam jet in molten sodium. Application to the wastage of steam generators of FBR power plants

International Nuclear Information System (INIS)

Lestrat, Patrice.

1982-11-01

This study aims to analyze and explain the structure of a reactive jet of water steam in liquid sodium, as from a ligh pressure tank and an orifice of very small section. The prior understanding of this reactive jet makes it possible to explain certain results of erosion-corrosion (Wastage) that can occur in the steam generators of breader reactor power stations. This study gave rise to an experimental simulation (plane jet of water steam on a bed of sodium), as well as to suggesting a reactive jet model according to the principle of an ''immersed Na-H 2 O diffusion flame'' [fr

A Rectangular Planar Spiral Antenna for GIS Partial Discharge Detection

Directory of Open Access Journals (Sweden)

Xiaoxing Zhang

2014-01-01

Full Text Available A rectangular planar spiral antenna sensor was designed for detecting the partial discharge in gas insulation substations (GIS. It can expediently receive electromagnetic waves leaked from basin-type insulators and can effectively suppress low frequency electromagnetic interference from the surrounding environment. Certain effective techniques such as rectangular spiral structure, bow-tie loading, and back cavity structure optimization during the antenna design process can miniaturize antenna size and optimize voltage standing wave ratio (VSWR characteristics. Model calculation and experimental data measured in the laboratory show that the antenna possesses a good radiating performance and a multiband property when working in the ultrahigh frequency (UHF band. A comparative study between characteristics of the designed antenna and the existing quasi-TEM horn antenna was made. Based on the GIS defect simulation equipment in the laboratory, partial discharge signals were detected by the designed antenna, the available quasi-TEM horn antenna, and the microstrip patch antenna, and the measurement results were compared.

Premature and stable critical heat flux for downward flow in a narrow rectangular channel

International Nuclear Information System (INIS)

Lee, Juhyung; Chang, Soon Heung; Jeong, Yong Hoon; Jo, Daeseong

2014-01-01

It has been recommended that RRs and MTRs be designed to have sufficient margins for CHF and the onset of FI as well, since unstable flow could leads to premature CHF under very low wall heat flux in comparison to stable CHF. Even the fact and previous studies, however, the understanding of relationship among FI, premature CHF and stable CHF is not sufficient to date. In this regards, subcooled flow boiling in a vertical rectangular channel was experimentally investigated to enhance the understanding of the CHF and the effect of the two-phase flow instability on it under low pressure conditions, especially for downward flow which was adopted for Jordan Research and Training Reactor (JRTR) and Kijang research reactor (KJRR) to achieve easier fuel and irradiation rig loading. In this study, CHF for downward flow of water under low pressure in narrow rectangular channel was experimentally investigated. For conditions such as downward flow, narrow rectangular channel and low pressure, it has been deduced from literature that flow instability could largely influence on triggering CHF at lower heat flux, i. e. premature CHF. Total 54 CHF data, which includes premature and stable data was obtained for various fluid conditions and system configurations including inlet stiffness. The upper and lower boundaries of CHF were newly proposed based on the experiment

g-Weak Contraction in Ordered Cone Rectangular Metric Spaces

Directory of Open Access Journals (Sweden)

S. K. Malhotra

2013-01-01

Full Text Available We prove some common fixed-point theorems for the ordered g-weak contractions in cone rectangular metric spaces without assuming the normality of cone. Our results generalize some recent results from cone metric and cone rectangular metric spaces into ordered cone rectangular metric spaces. Examples are provided which illustrate the results.

Investigation of imaging properties for submillimeter rectangular pinholes

Energy Technology Data Exchange (ETDEWEB)

Xia, Dan, E-mail: dxia@uchicago.edu [The Department of Radiology, The University of Chicago, Chicago, Illinois 60637 (United States); Moore, Stephen C., E-mail: scmoore@bwh.harvard.edu, E-mail: miaepark@bwh.harvard.edu, E-mail: mcervo@bwh.harvard.edu; Park, Mi-Ae, E-mail: scmoore@bwh.harvard.edu, E-mail: miaepark@bwh.harvard.edu, E-mail: mcervo@bwh.harvard.edu; Cervo, Morgan, E-mail: scmoore@bwh.harvard.edu, E-mail: miaepark@bwh.harvard.edu, E-mail: mcervo@bwh.harvard.edu [Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts 02115 (United States); Metzler, Scott D., E-mail: metzler@upenn.edu [The Department of Radiology, The University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

2015-12-15

Purpose: Recently, a multipinhole collimator with inserts that have both rectangular apertures and rectangular fields of view (FOVs) has been proposed for SPECT imaging since it can tile the projection onto the detector efficiently and the FOVs in transverse and axial directions become separable. The purpose of this study is to investigate the image properties of rectangular-aperture pinholes with submillimeter apertures sizes. Methods: In this work, the authors have conducted sensitivity and FOV experiments for 18 replicates of a prototype insert fabricated in platinum/iridium (Pt/Ir) alloy with submillimeter square-apertures. A sin{sup q}θ fit to the experimental sensitivity has been performed for these inserts. For the FOV measurement, the authors have proposed a new formula to calculate the projection intensity of a flood image on the detector, taking into account the penumbra effect. By fitting this formula to the measured projection data, the authors obtained the acceptance angles. Results: The mean (standard deviation) of fitted sensitivity exponents q and effective edge lengths w{sub e} were, respectively, 10.8 (1.8) and 0.38 mm (0.02 mm), which were close to the values, 7.84 and 0.396 mm, obtained from Monte Carlo calculations using the parameters of the designed inserts. For the FOV measurement, the mean (standard deviation) of the transverse and axial acceptances were 35.0° (1.2°) and 30.5° (1.6°), which are in good agreement with the designed values (34.3° and 29.9°). Conclusions: These results showed that the physical properties of the fabricated inserts with submillimeter aperture size matched our design well.

Fastener investigation in JET

Energy Technology Data Exchange (ETDEWEB)

Bunting, P., E-mail: patrick.bunting@ccfe.ac.uk; Thompson, V.; Riccardo, V.

2016-11-15

Highlights: • Experimental work to identify the cause of a bolt seizure inside the JET vessel. • Taguchi method used to reduce tests to 16 while covering 5 parameters. • Experimental work was unable to reproduce bolt seizure. • Thread contamination had little effect on the bolt performance. - Abstract: JET is an experimental fusion reactor consisting of magnetically confined, high temperature plasma inside a large ultra-high vacuum chamber. The inside of the chamber is protected from the hot plasma with tiles made from beryllium, tungsten, carbon composites and other materials bolted to the vessel wall. The study was carried out in response to a JET fastener seizing inside the vacuum vessel. The following study looks at characterising the magnitude of the individual factors affecting the fastener break away torque. This was carried out using a statistical approach, the Taguchi method: isolating the net effect of individual factors present in a series of tests [1](Grove and Davis, 1992). Given the severe environment within the JET vessel due to the combination of heat, ultra-high vacuum and the high contact pressure in bolt threads, the contributions of localised diffusion bonding is assessed in conjunction with various combinations of bolt and insert material.

Experimental and numerical study on premixed hydrogen/air flame propagation in a horizontal rectangular closed duct

Energy Technology Data Exchange (ETDEWEB)

Xiao, Huahua; Wang, Qingsong; He, Xuechao; Sun, Jinhua; Yao, Liyin [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026 (China)

2010-02-15

Hydrogen is a promising energy in the future, and it is desirable to characterize the combustion behavior of its blends with air. The premixed hydrogen/air flame microstructure and propagation in a horizontal rectangular closed duct were recorded using high-speed video and Schlieren device. Numerical simulation was also performed on Fluent CFD code to compare with the experimental result. A tulip flame is formed during the flame propagating, and then the tulip flame formation mechanism was proposed based on the analysis. The induced reverse flow and vortex motion were observed both in experiment and simulation. The interactions among the flame, reverse flow and vortices in the burned gas change the flame shape and ultimately it develops into a tulip flame. During the formation of the tulip flame, the tulip cusp slows down and stops moving after its slightly forward moving, and then, it starts to move backward and keeps on a longer time, after that, it moves forward again. The structure of the tulip flame is becoming less stable with its length decreasing in flame propagation direction. The flame thickness increases gradually which is due to turbulence combustion. (author)

Experimental investigation of onset of nucleate boiling in this rectangular channels

International Nuclear Information System (INIS)

Belhadj, M.; Christensen, R.N.; Aldemir, T.

1988-01-01

The 10 kW, HEU fueled Ohio State University Research Reactor (OSURR) will be upgraded to operate with plate type LEU U 3 Si 2 , fuel elements in the power range 250-500 kW. The core will be cooled by natural convection and an onset of nucleate boiling (ONB) margin of 1.2 will be maintained in the hot channel under steady-state operation. The validity of the correlations used for predicting ONB in plate type research reactors is not known for low heat flux-low velocity flows. An experiment has been set up at The Ohio State University to investigate ONB for laminar flow in this rectangular channels. The results show that: The Bergles-Rohsenow correlation and the correlation proposed by Ricque and Siboul predict higher and lower ONB fluxes than actual, respectively. The ONB heat flux is flow velocity dependent

Combining resummed Higgs predictions across jet bins

Energy Technology Data Exchange (ETDEWEB)

Boughezal, Radja [Argonne National Laboratory, IL (United States). High Energy Physics Division; Liu, Xiaohui; Petriello, Frank [Argonne National Laboratory, IL (United States). High Energy Physics Division; Northwestern Univ., Evanston, IL (United States). Dept. of Physics and Astronomy; Tackmann, Frank J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Walsh, Jonathan R. [California Univ., Berkeley, CA (United States). Ernest Orlando Lawrence Berkeley Laboratory; California Univ., Berkeley, CA (United States). Center for Theoretical Physics

2013-12-15

Experimental analyses often use jet binning to distinguish between different kinematic regimes and separate contributions from background processes. To accurately model theoretical uncertainties in these measurements, a consistent description of the jet bins is required. We present a complete framework for the combination of resummed results for production processes in different exclusive jet bins, focusing on Higgs production in gluon fusion as an example. We extend the resummation of the H+1-jet cross section into the challenging low transverse momentum region, lowering the uncertainties considerably. We provide combined predictions with resummation for cross sections in the H+0-jet and H+1-jet bins, and give an improved theory covariance matrix for use in experimental studies. We estimate that the relevant theoretical uncertainties on the signal strength in the H{yields}WW{sup *} analysis are reduced by nearly a factor of 2 compared to the current value.

Accelerating recovery from jet lag: prediction from a multi-oscillator model and its experimental confirmation in model animals

Science.gov (United States)

Kori, Hiroshi; Yamaguchi, Yoshiaki; Okamura, Hitoshi

2017-04-01

The endogenous circadian clock drives oscillations that are completely synchronized with the environmental day-night rhythms with a period of approximately 24 hours. Temporal misalignment between one’s internal circadian clock and the external solar time often occurs in shift workers and long-distance travelers; such misalignments are accompanied by sleep disturbances and gastrointestinal distress. Repeated exposure to jet lag and rotating shift work increases the risk of lifestyle-related diseases, such as cardiovascular complaints and metabolic insufficiencies. However, the mechanism behind the disruption of one’s internal clock is not well understood. In this paper, we therefore present a new theoretical concept called “jet lag separatrix” to understand circadian clock disruption and slow recovery from jet lag based on the mathematical model describing the hierarchical structure of the circadian clock. To demonstrate the utility of our theoretical study, we applied it to predict that re-entrainment via a two-step jet lag in which a four-hour shift of the light-dark cycle is given in the span of two successive days requires fewer days than when given as a single eight-hour shift. We experimentally verified the feasibility of our theory in C57BL/6 strain mice, with results indicating that this pre-exposure of jet lag is indeed beneficial.

Resonant frequency function of thickness-shear vibrations of rectangular crystal plates.

Science.gov (United States)

Wang, Ji; Yang, Lijun; Pan, Qiaoqiao; Chao, Min-Chiang; Du, Jianke

2011-05-01

The resonant frequencies of thickness-shear vibrations of quartz crystal plates in rectangular and circular shapes are always required in the design and manufacturing of quartz crystal resonators. As the size of quartz crystal resonators shrinks, for rectangular plates we must consider effects of both length and width for the precise calculation of resonant frequency. Starting from the three-dimensional equations of wave propagation in finite crystal plates and the general expression of vibration modes, we obtained the relations between frequency and wavenumbers. By satisfying the major boundary conditions of the dominant thickness-shear mode, three wavenumber solutions are obtained and the frequency equation is constructed. It is shown the resonant frequency of thickness-shear mode is a second-order polynomial of aspect ratios. This conforms to known results in the simplest form and is applicable to further analytical and experimental studies of the frequency equation of quartz crystal resonators.

Far-field potentials in cylindrical and rectangular volume conductors.

Science.gov (United States)

Dumitru, D; King, J C; Rogers, W E

1993-07-01

The occurrence of a transient dipole is one method of producing a far-field potential. This investigation qualitatively defines the characteristics of the near-field and far-field electrical potentials produced by a transient dipole in both cylindrical and rectangular volume conductors. Most body segments of electrophysiologic interest such as arms, legs, thorax, and neck are roughly cylindrical in shape. A centrally located dipole generator produces a nonzero equipotential region which is found to occur along the cylindrical wall at a distance from the dipole of approximately 1.4 times the cylinder's radius and 1.9 times the cylinder's radius for the center of the cylinder. This distance to the equi-potential zone along the surface wall expands but remains less than 3.0 times the cylindrical radius when the dipole is eccentrically placed. The magnitude of the equipotential region resulting from an asymmetrically placed dipole remains identical to that when the dipole is centrally located. This behavior is found to be very similar in rectangular shallow conducting volumes that model a longitudinal slice of the cylinder, thus allowing a simple experimental model of the cylinder to be utilized. Amplitudes of the equipotential region are inversely proportional to the cylindrical or rectangular volume's cross-sectional area at the location of dipolar imbalance. This study predicts that referential electrode montages, when placed at 3.0 times the radius or greater from a dipolar axially aligned far-field generator in cylindrical homogeneous volume conductors, will record only equipotential far-field effects.

Numerical Simulation and Industrial Experimental Research on the Coherent Jet with "CH4 + N2" Mixed Fuel Gas

Science.gov (United States)

Hu, Shaoyan; Zhu, Rong; Dong, Kai; Liu, Runzao

2018-06-01

Coherent jet technology is widely used in the electric arc furnace (EAF) steelmaking process to deliver more energy and momentum into the molten steel bath. Meanwhile, the characteristics of a coherent jet using pure CH4 as the fuel gas have been well investigated in previous studies. To reduce the consumption of CH4, coherent jet technology using "CH4 + N2" mixed fuel gas instead of pure CH4 was proposed and studied in detail by numerical simulation in the present work. The Eddy Dissipation Concept model, which has detailed chemical kinetic mechanisms, was adopted to model the fuel gas combustion reactions. Experimental measurements were carried out to validate the accuracy of the computational model. The present study shows that the jet characteristics of the main oxygen improve along with the increase of the CH4 ratio in fuel gas and with the increase of the flow rate of fuel gas. When the CH4 ratio in the fuel gas is 25 pct, the fuel gas flow rate only has a limited influence on the jet characteristics, unlike the rest of the fuel gas compositions, because a high N2 proportion deteriorates the combustion performance and leads to severe incomplete combustion. Moreover, a false potential core phenomenon was observed and explained in the present study. Based on the average values, the jet length of a coherent jet with 75 pct CH4 can achieve 89.8 pct of that with 100 pct CH4. Finally, an industrial experiment was carried out on a commercial 100t EAF using coherent jet with 75 pct CH4, showing that the average CH4 consumption was reduced from 3.84 to 3.05 Nm3 t-1 under the premise of no obvious changes in the other production indexes.

Numerical investigation of boiling heat transfer on hydrocarbon mixture refrigerant in vertical rectangular minichannel

OpenAIRE

Huixing Li; Yu Liu

2016-01-01

In order to investigate the characteristics of boiling heat transfer for hydrocarbon mixture refrigerant in plate-fin heat exchanger which is used in the petrochemical industry field, a model was established on boiling heat transfer in vertical rectangular channel. The simulated results were compared with the experimental data from literature. The results show that the deviation between the simulated results and experimental data is within ±15%. Meanwhile, the characteristic of boiling heat t...

Theoretical and experimental analysis of electroweak corrections to the inclusive jet process. Development of extreme topologies detection methods

International Nuclear Information System (INIS)

Meric, Nicolas

2013-01-01

We have studied the behaviour of the inclusive jet, W+jets and Z+jets processes from the phenomenological and experimental point of view in the ATLAS experiment at LHC in order to understand how important is the impact of Sudakov logarithms on electroweak corrections and in the associated production of weak vector boson and jets at LHC. We have computed the amplitude of the real electroweak corrections to the inclusive jet process due to the real emission of weak vector bosons from jets. We have done this computation with the MCFM and NLOjet++ generators at 7 TeV, 8 TeV and 14 TeV. This study shows that, for the inclusive jet process, the partial cancellation of the virtual weak corrections (due to weak bosons in loops) by the real electroweak corrections occurs. This effect shows that Bloch-Nordsieck violation is reduced for this process. We have then participated to the measure of the differential cross-section for these different processes in the ATLAS experiment at 7 TeV. In particular we have been involved into technical aspects of the measurement such as the study of the QCD background to the W+jets process in the muon channel. We have then combined the different measurements in this channel to compare their behaviour. This tends to show that several effects are giving to the electroweak corrections their relative importance as we see an increase of the relative contribution of weak bosons with jets processes to the inclusive jet process with the transverse momentum of jets, if we explicitly ask for the presence of electroweak bosons in the final state. This study is currently only a preliminary study and aims at showing that this study can be useful to investigate the underlying structure of these processes. Finally we have studied the noises affecting the ATLAS calorimeter. This has allowed for the development of a new way to detect problematic events using well known theorems from statistics. This new method is able to detect bursts of noise and

Experimental study of highly viscous impinging jets

Energy Technology Data Exchange (ETDEWEB)

Gomon, M. [Univ. of Texas, Austin, TX (United States). Dept. of Mechanical Engineering

1998-12-01

The objective of this research is to study the behavior of highly viscous gravity-driven jets filling a container. Matters of interest are the formation of voids in the fluid pool during the filling process and the unstable behavior of the fluid in the landing region which manifests itself as an oscillating motion. The working fluids used in this research are intended to simulate the flow behavior of molten glass. Qualitative and quantitative results are obtained in a parametric study. The fraction of voids present in the fluid pool after the filling of the container is measured for different parameter values of viscosity and mass flow rate. Likewise, frequencies of the oscillating jet are measured. Results are inconclusive with regard to a correlation between parameter settings and void fractions. As for frequencies, power law correlations are established.

Experimental study of highly viscous impinging jets

International Nuclear Information System (INIS)

Gomon, M.

1998-12-01

The objective of this research is to study the behavior of highly viscous gravity-driven jets filling a container. Matters of interest are the formation of voids in the fluid pool during the filling process and the unstable behavior of the fluid in the landing region which manifests itself as an oscillating motion. The working fluids used in this research are intended to simulate the flow behavior of molten glass. Qualitative and quantitative results are obtained in a parametric study. The fraction of voids present in the fluid pool after the filling of the container is measured for different parameter values of viscosity and mass flow rate. Likewise, frequencies of the oscillating jet are measured. Results are inconclusive with regard to a correlation between parameter settings and void fractions. As for frequencies, power law correlations are established

Theoretical study on device efficiency of pulsed liquid jet pump

International Nuclear Information System (INIS)

Gao Chuanchang; Lu Hongqi; Wang Shicheng; Cheng Mingchuan

2001-01-01

The influence of the main factors on device efficiency of pulsed liquid jet pump with gas-liquid piston is analysed, the theoretical equation and its time-averaged solution of pulsed liquid jet pump device efficiency are derived. The theoretical and experimental results show that the efficiency of transmission of energy and mass to use pulsed jet is greatly raised, compared with steady jet, in the same device of liquid jet pump. The calculating results of time-averaged efficiency of pulsed liquid jet pump are approximately in agreement with the experimental results in our and foreign countries

Investigation of supersonic jets shock-wave structure

Science.gov (United States)

Zapryagaev, V. I.; Gubanov, D. A.; Kavun, I. N.; Kiselev, N. P.; Kundasev, S. G.; Pivovarov, A. A.

2017-10-01

The paper presents an experimental studies overview of the free supersonic jet flow structure Ma = 1.0, Npr = 5, exhausting from a convergent profiled nozzle into a ambient space. Also was observed the jets in the presence of artificial streamwise vortices created by chevrons and microjets located on the nozzle exit. The technique of experimental investigation, schlieren-photographs and schemes of supersonic jets, and Pitot pressure distributions, are presented. A significant effect of vortex generators on the shock-wave structure of the flow is shown.

Effect on two-phase flow frictional pressure drop characteristic in narrow rectangular channel at fluctuant condition

International Nuclear Information System (INIS)

Li Changwei; Cao Xiaxin; Sun Licheng; Jin Guangyuan

2013-01-01

Based on the data of two-phase flow in narrow rectangular channel, the influence of the two-phase flow friction characteristic under the different fluctuant states was analyzed. Through analyzing the experimental data, it is shown that the fluctuant amplitude of the friction pressure drop is affected slightly by the fluctuant period in narrow rectangular channel, but the frequency of the friction pressure drop fluctuation is changed. However, the change of fluctuant period is of little effect on the average frictional pressure drop. Comparing the φ l 2 (φ g 2 )-X variation curves at static condition with the ones at fluctuant condition, using the L-M method, it's found that the two phase frictional pressure drop in the narrow rectangular channel under the fluctuant state can be calculated by the φ l 2 (φ g 2 )-X variation curve at static condition. (authors)

Size effect of the elastic modulus of rectangular nanobeams: Surface elasticity effect

International Nuclear Information System (INIS)

Yao Hai-Yan; Fan Wen-Liang; Yun Guo-Hong

2013-01-01

The size-dependent elastic property of rectangular nanobeams (nanowires or nanoplates) induced by the surface elasticity effect is investigated by using a developed modified core-shell model. The effect of surface elasticity on the elastic modulus of nanobeams can be characterized by two surface related parameters, i.e., inhomogeneous degree constant and surface layer thickness. The analytical results show that the elastic modulus of the rectangular nanobeam exhibits a distinct size effect when its characteristic size reduces below 100 nm. It is also found that the theoretical results calculated by a modified core-shell model have more obvious advantages than those by other models (core-shell model and core-surface model) by comparing them with relevant experimental measurements and computational results, especially when the dimensions of nanostructures reduce to a few tens of nanometers. (condensed matter: structural, mechanical, and thermal properties)

Power efficiency of the active boundary layer control around the hump by a slotted synthetic jet generator

Directory of Open Access Journals (Sweden)

Pick Petr

2015-01-01

Full Text Available The present contribution summarizes the power efficiency of the active flow control of the boundary layer of air around a hump. The synthetic jet generator with a rectangular output part, i.e. a slot, is actuated using a modulated signal. The actuation of the synthetic jet is carried out by modulating the input voltage of acoustic transducers of the generator. This causes the decrease of the loss coefficient and the change of the mixing size area (e.g. wake. A comparison of three types of modulating signals and their influence on the loss coefficient is performed. The main advantages of modulated signal are then described.

Regimes of Two-Phase Flow in Short Rectangular Channel

Science.gov (United States)

Chinnov, Evgeny A.; Guzanov, Vladimir V.; Cheverda, Vyacheslav; Markovich, Dmitry M.; Kabov, Oleg A.

2009-08-01

Experimental study of two-phase flow in the short rectangular horizontal channel with height 440 μm has been performed. Characteristics of liquid motion inside the channel have been registered and measured by the Laser Induced Fluorescence technique. New information has allowed determining more precisely the characteristics of churn regime and boundaries between different regimes of two-phase flow. It was shown that formation of some two-phase flow regimes and transitions between them are determined by instability of the flow in the lateral parts of the channel.

Experimental Flow Performance Evaluation of novel miniaturized Advanced Piezoelectric Dual Cooling Jet

International Nuclear Information System (INIS)

De Bock, H P J; Whalen, B P; Chamarthy, P; Jackson, J L

2012-01-01

In recent years, electronics systems have significantly reduced in size at maintained or increased functionality. This trend has led to an increased demand for smaller and more capable thermal management. However, miniaturization of conventional fan and heat sink cooling systems introduce significant size, weight and efficiency challenges. In this study the flow performance of a novel alternative thin form-factor cooling solution, the advanced piezoelectric dual cooling jet(DCJ), is evaluated. A DCJ is a system where two piezoelectric actuators are excited to produce air flow. The total height of the device is about 1mm. The design of the experimental method for evaluating the equivalent fan-curve of the DCJ device is described in detail. Experimental results in comparison to conventional fan solutions are provided. The DCJ is expected to be a good candidate for thermal management in next generation thin profile consumer electronics.

Large - scale Rectangular Ruler Automated Verification Device

Science.gov (United States)

Chen, Hao; Chang, Luping; Xing, Minjian; Xie, Xie

2018-03-01

This paper introduces a large-scale rectangular ruler automated verification device, which consists of photoelectric autocollimator and self-designed mechanical drive car and data automatic acquisition system. The design of mechanical structure part of the device refer to optical axis design, drive part, fixture device and wheel design. The design of control system of the device refer to hardware design and software design, and the hardware mainly uses singlechip system, and the software design is the process of the photoelectric autocollimator and the automatic data acquisition process. This devices can automated achieve vertical measurement data. The reliability of the device is verified by experimental comparison. The conclusion meets the requirement of the right angle test procedure.

Effect of aspect ratio on the laminar-to-turbulent transition in rectangular channel

International Nuclear Information System (INIS)

Wang Chang; Gao Puzhen; Tan Sichao; Xu Chao

2012-01-01

Highlights: ► Effect of aspect ratio on the transition Reynolds number in rectangular channel is studied. ► Prediction correlation for transition Reynolds number is proposed. ► The initiation location of flow transition is studied. - Abstract: The critical Reynolds number of the laminar-to-turbulent transition in the rectangular channel is investigated based on the energy gradient method. The results show that the critical Reynolds number decreases with the increasing aspect ratio. However, the relative location of laminar breakdown does not migrate significantly with the variation of the aspect ratio. In addition, a theoretical correlation as a function of the aspect ratio is proposed to calculate the transition Reynolds number, and the predicted values are in good agreement with the experimental data obtained in the published literatures.

Blue jets and gigantic jets: transient luminous events between thunderstorm tops and the lower ionosphere

International Nuclear Information System (INIS)

Pasko, V P

2008-01-01

An overview of general phenomenology and proposed physical mechanisms of large scale electrical discharges termed 'blue jets' and 'gigantic jets' observed at high altitude in the Earth's atmosphere above thunderstorms is presented. The primary emphasis is placed on summarizing available experimental data on the observed morphological features of upward jet discharges and on the discussion of recently advanced theories describing electrodynamic conditions, which facilitate escape of conventional lightning leaders from thundercloud tops and their upward propagation toward the ionosphere. It is argued that the filamentary plasma structures observed in blue jet and gigantic jet discharges are directly linked to the processes in streamer zones of lightning leaders, scaled by a significant reduction of air pressure at high altitudes.

Mechanical behavior analysis on electrostatically actuated rectangular microplates

Science.gov (United States)

Li, Zhikang; Zhao, Libo; Jiang, Zhuangde; Ye, Zhiying; Dai, Lu; Zhao, Yulong

2015-03-01

Microplates are widely used in various MEMS devices based on electrostatic actuation such as MEMS switches, micro pumps and capacitive micromachined ultrasonic transducers (CMUTs). Accurate predictions for the mechanical behavior of the microplate under electrostatic force are important not only for the design and optimization of these electrostatic devices but also for their operation. This paper presents a novel reduced-order model for electrostatically actuated rectangular and square microplates with a new method to treat the nonlinear electrostatic force. The model was developed using Galerkin method which turned the partial-differential equation governing the microplates into an ordinary equation system. Using this model and cosine-like deflection functions, explicit expressions were established for the deflection and pull-in voltage of the rectangular and square microplates. The theoretical results were well validated with the finite element method simulations and experimental data of literature. The expressions for the deflection analysis are able to predict the deflection up to the pull-in position with an error less than 5.0%. The expressions for the pull-in voltage analysis can determine the pull-in voltages with errors less than 1.0%. Additionally, the method to calculate the capacitance variation of the electrostatically actuated microplates was proposed. These theoretical analyses are helpful for design and optimization of electrostatically actuated microdevices.

Experimental and Theoretical Investigation of Impinging Jet Ventilation at Different Cross Sectional Area of Supply Air Duct

Directory of Open Access Journals (Sweden)

Ala'a Abbas Mahdi

2018-03-01

Full Text Available  An experimental and computational analysis of temperature and velocity distribution in an office room have been studied. Office room of dimensions (3m x 1.75m x 3m with two cross sectional types of supply air duct in the experimental part and three different cross sectional types of supply air duct in the theoretical part is usual as a tested model. The RNG k-  turbulence model was employed to solve the governing equations numerically and validated by comparing the numerical results with experimental data. The impinging jet concept has been proposed as a new ventilation strategy for use in office and industrial buildings. The present work focuses on evaluating the performance of a new impinging jet ventilation. In a theoretical study three types of supply air duct are adopted which are square supply air duct (Type-I, semi-elliptic supply air duct (Type-II and rectangle supply air duct (Type-III for two cases of air outlet terminal height from room foot level, 0.14h (case-I & 0.1h (case-II. The third type (rectangle duct gives lowest effective and discomfort conditions when compared with the other two types. This study investigated a number of factors influencing draught discomfort and temperature stratification in an office environment equipped with impinging jet ventilation IJV. The factors considered to be: shape of the air supply device, supply airflow rate and supply air temperature. Acceptable Air Distribution Performance Index (ADPI, effective temperature, and ventilation efficiency obtained that the square cross sectional area of supply air duct at 0.1h (case-II height from foot level gives more acceptable indoor air quality and human thermal comfort when compared with the other types. Also, this type gives good air distribution system not only promotes a comfortable and healthy environment for occupants, but also contributes to energy conservation.

Jets in heavy ion collisions with CMS

CERN Document Server

Salur, Sevil

2016-01-01

Jet physics in heavy ion collisions is a rich field which has been rapidly evolving since the first observations of medium interactions at RHIC through back-to-back hadron correlations and at LHC via reconstructed jets. In order to completely characterize the final state via jet-medium interactions and distinguish between competing energy loss mechanisms complementary and robust jet observables are investigated. Latest developments of jet finding techniques and their applications to heavy ion environments are discussed with an emphasis given on experimental results from CMS experiment.

Numerical simulation of sloshing in rectangular tanks with OpenFOAM CFD Package

International Nuclear Information System (INIS)

Andreski, Filip; Markov, Zoran; Diebold, Louis; Gazzola, Thomas

2009-01-01

The aim of this paper is to simulate the sloshing phenomenon using OpenFOAM CFD software package. The present paper treats a 2D numerical simulation of a partially filled tank that is located on a LNG carrier. Experiments were done on a rectangular tank excited with different excitation periods and amplitudes and the pressure was measured at certain locations on the tank walls. The goal of this research is to compare the experimental data for the pressure with the pressure results obtained with the CFD software. It is shown that the obtained results match well with the experimental data.

Studies on the properties of turbulent jets, 6

International Nuclear Information System (INIS)

Ishigaki, Hiroshi

1984-01-01

The round turbulent buoyant jet issuing vertically into quiescent fluid is studied analytically. Formulae on maximum velocity, temperature, concentration and entrainment rate are derived. These formulae agree well with the available experimental data for whole region of jet and plume. Quantitative classification as to the flow regime of jet, transition and plume are given for the nondimensional distance from jet exit. (author)

Measurement of electric field distribution along the plasma column in Microwave jet discharges at atmospheric pressure

International Nuclear Information System (INIS)

Razzak, M. Abdur; Takamura, Shuichi; Tsujikawa, Takayuki; Shibata, Hideto; Hatakeyama, Yuto

2009-01-01

A new technique for the direct measurement of electric field distribution along the plasma column in microwave jet discharges is developed and employed. The technique is based on a servomotor-controlled reciprocating antenna moving along the nozzle axis and plasma column. The measurement technique is applied to a rectangular waveguide-based 2.45 GHz argon and helium plasma jets generated by using the modified TIAGO nozzle at atmospheric pressure with a microwave power of less than 500 W. The measurement has been done with and without igniting the plasma jet in order to investigate the standing wave propagation along the nozzle axis and plasma column. It is observed that the electric field decay occurs slowly in space with plasma ignition than that of without plasma, which indicates the surface electromagnetic wave propagation along the plasma column in order to sustain the plasma jet. This study enables one to design, determine and optimize the size and structure of launcher nozzle, which plays an important role for the stable and efficient microwave plasma generators. (author)

Monte Carlo study for the dynamical fluctuations inside a single jet in 2-jet events

International Nuclear Information System (INIS)

Zhang Kunshi; Liu Lianshou; Yin Jianwu; Chen Gang; Liu Chao

2002-01-01

The dynamical fluctuations inside a single jet in the 2-jet events produced in e + e - collisions at 91.2 GeV have been studied using Monte Carlo method. The results show that, the anisotropy of dynamical fluctuations inside a single jet changes remarkably with the variation of the cut parameter y cut . A transition point (γ p t = γ ψ ≠γ y ) exists, where the dynamical fluctuations are anisotropic in the longitudinal-transverse plan and isotropic in the transverse planes. It indicates that the y cut corresponding to the transition point is a physically reasonable cutting parameter for selecting jets and, meanwhile, the relative transverse momentum k t at the transition point is the scale for the determination of physical jets. This conclusion is in good agreement with the experimental fact that the third jet (gluon jet) was historically first discovered in the energy region 17-30 GeV in e + e - collisions

Jets and QCD

International Nuclear Information System (INIS)

Ali, A.; Kramer, G.

2010-12-01

The observation of quark and gluon jets has played a crucial role in establishing Quantum Chromodynamics [QCD] as the theory of the strong interactions within the Standard Model of particle physics. The jets, narrowly collimated bundles of hadrons, reflect configurations of quarks and gluons at short distances. Thus, by analysing energy and angular distributions of the jets experimentally, the properties of the basic constituents of matter and the strong forces acting between them can be explored. In this review we summarise the properties of quark and gluon jets and the impact of their observation on Quantum Chromodynamics, primarily the discovery of the gluons as the carriers of the strong force. Focusing on these basic points, jets in e + e - collisions will be in the foreground of the discussion. In addition we will delineate the role of jets as tools for exploring other particle aspects in ep and pp/p anti p collisions - quark and gluon densities in protons, measurements of the QCD coupling, fundamental 2-2 quark/gluon scattering processes, but also the impact of jet decays of top quarks, and W ± ,Z bosons on the electroweak sector. The presentation to a large extent is formulated in a non-technical language with the intent to recall the significant steps historically and convey the significance of this field also to communities beyond high energy physics. (orig.)

Jets and QCD

Energy Technology Data Exchange (ETDEWEB)

Ali, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kramer, G. [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik

2010-12-15

The observation of quark and gluon jets has played a crucial role in establishing Quantum Chromodynamics [QCD] as the theory of the strong interactions within the Standard Model of particle physics. The jets, narrowly collimated bundles of hadrons, reflect configurations of quarks and gluons at short distances. Thus, by analysing energy and angular distributions of the jets experimentally, the properties of the basic constituents of matter and the strong forces acting between them can be explored. In this review we summarise the properties of quark and gluon jets and the impact of their observation on Quantum Chromodynamics, primarily the discovery of the gluons as the carriers of the strong force. Focusing on these basic points, jets in e{sup +}e{sup -} collisions will be in the foreground of the discussion. In addition we will delineate the role of jets as tools for exploring other particle aspects in ep and pp/p anti p collisions - quark and gluon densities in protons, measurements of the QCD coupling, fundamental 2-2 quark/gluon scattering processes, but also the impact of jet decays of top quarks, and W{sup {+-}},Z bosons on the electroweak sector. The presentation to a large extent is formulated in a non-technical language with the intent to recall the significant steps historically and convey the significance of this field also to communities beyond high energy physics. (orig.)

Visualization of conventional and combusting subsonic jet instabilities

CERN Document Server

Kozlov, Victor; Litvinenko, Yury

2016-01-01

Based on new information obtained on free microjets, this book explains the latest phenomena in flame evolution in the presence of a transverse acoustic field with round and plane propane microjet combustion. It gives an overview of recent experimental results on instability and dynamics of jets at low Reynolds numbers and provides the reader, step by step, with the milestones and recent advances in jet flow stability and combustion. Readers will also discover a clarification of the differences between top-hat and parabolic round and plane jet instability. Chapters demonstrate features of the interaction between jet and crossflow, and how experimental data testify to similarities of the perturbed flow patterns of laminar and turbulent round jets. A similar response of the jets to external acoustic oscillations is shown, as well as the peculiarities of the effect of a transverse acoustic field on downstream evolution of round and plane macro- and microjets. Basic features of round and plane, macro and micro je...

The demagnetizing factors for the rectangular samples

International Nuclear Information System (INIS)

Akishin, P.G.; Gaganov, I.A.

1990-01-01

The influence of the demagnetization effect on the distribution of internal magnetic fields for finite samples is considered. The boundary integral method is used to compute the space distribution of the magnetic field in rectangular samples. On the basis of these calculations we compute the distribution of demagnetization factors in the sample for μSR experimental set-up with the real field geometry. The corresponding mathematical expectation and dispersion of this distribution are estimated. The results of the calculation are used in the analysis of the μSR data obtained for high T c superconductors. It is shown for these compounds that the correction to the penetration depth related to the broadening of the field distribution, is not more than 5%. 8 refs.; 2 figs.; 1 tab

Experimental study on the effect of gap size to CCFL and CHF in a vertical of narrow rectangular channel during quenching process

International Nuclear Information System (INIS)

Juarsa, Mulya; Putra, Nandy; Septiadi, Wayan Nata; Antariksawan, Anhar Riza

2014-01-01

Highlights: • Quenching in narrow rectangular channel with gap sizes variation was investigated. • The mechanism of counter-current flow depends on gap sizes variation. • The results confirmed the existence of CCFL in narrow rectangular channels. • CHF and mass flux gradient in the quenching was about 0.22 times than steady state. • Modification of CHF and mass flow rate dimensionless correlation was established. - Abstract: The quenching process has become an important thermal management study to intensify the safety margin for the integrity of the reactor vessel under the core meltdown condition. The boiling heat transfer mechanism in the channel is one aspect that needs further examination. The present study aimed to investigate the effect of the differences in channel gap size to counter-current flow limitation (CCFL) and critical heat flux (CHF) during transient cooling in atmospheric pressure and quenching using two vertical plates with 1 mm, 2 mm, and 3 mm gap sizes and heated length of 1100 mm. The initial temperature of the plate was set at 600 °C. Cooling water mass flow rate and sib-cooled temperature were set at about 0.089 kg/s and 90 °C, respectively. Calculations were performed to obtain the CHF value through the boiling curve using transient temperature data. Non-dimensional correlations from other research study was used in this research. The influence of gap sizes on CCFL and CHF resulted in an increased value of CHF relative to gap size; additionally, the CHF for gap sizes of 2 mm and 3 mm increased about 34.4% and 140.5%, respectively, compared to the CHF for the 1 mm gap size. In this research, a curve map of the relationship between non-dimensional CHF and non-dimensional mass flux of water flowing downward shows that the correlation of this experimental study has a gradient number of about 0.22 similar to Mishima and Nishihara correlation. The results confirmed the existence of CCFL in the vertical narrow rectangular channels due

Analysis of multiplicities in e+e- interactions using 2-jet rates from different jet algorithms

International Nuclear Information System (INIS)

Dahiya, S.; Kaur, M.; Dhamija, S.

2002-01-01

The shoulder structure of charged particle multiplicity distribution measured in full phase space in e + e - interactions at various c.m. energies from 91 to 189 GeV has been analysed in terms of weighted superposition of two negative binomial distributions associated with 2-jet and multi-jet production. The 2-jet rates have been obtained from various jet algorithms. This phenomenological parametrization reproduces the shoulder structure behaviour quantitatively and improves the agreement with the experimental distributions than the conventional negative binomial distribution. The analysis at the higher energies where the shoulder structure appears more prominently, is important for the understanding of underlying structure. (author)

Experimental investigation of small scale geometries in a turbulent round jet

Energy Technology Data Exchange (ETDEWEB)

Gampert, Markus; Schaefer, Philip; Peters, Norbert, E-mail: mgampert@itv.rwth-aachen.de [Institute for Combustion Technology, RWTH Aachen Templergraben 64, 52056 Aachen (Germany)

2011-12-22

In the present work, we present a method to gather highly accurate three-dimensional measurements of a scalar field in order to experimentally validate the theory of dissipation elements as developped by Wang and Peters (2006, 2008). Combining a two-dimensional high-speed Rayleigh scattering technique with Taylor's hypothesis allows to resolve the concentration field of gaseous propane discharging into ambient air from a turbulent round jet at a Reynolds number (based on nozzle diameter and exit velocity) of 2,800 down to the Kolmogorov scale in every spatial direction. Based on the acquired data, the normalized probability density function of the length of dissipation elements P-tilde (l-tilde) is investigated at various downstream positions x/d = 15 - 40 and an excellent agreement with the theoretically derived model equation is obtained.

Random Young diagrams in a Rectangular Box

DEFF Research Database (Denmark)

Beltoft, Dan; Boutillier, Cédric; Enriquez, Nathanaël

We exhibit the limit shape of random Young diagrams having a distribution proportional to the exponential of their area, and confined in a rectangular box. The Ornstein-Uhlenbeck bridge arises from the fluctuations around the limit shape.......We exhibit the limit shape of random Young diagrams having a distribution proportional to the exponential of their area, and confined in a rectangular box. The Ornstein-Uhlenbeck bridge arises from the fluctuations around the limit shape....

Bubble departure diameter in narrow rectangular channel under rolling condition

Energy Technology Data Exchange (ETDEWEB)

Xie, T.; Chen, B.; Yan, X.; Xu, J.; Huang, Y.; Xiao, Z. [Nuclear Power Inst. of China, Chengdu, Sichuan (China)

2014-07-01

Forced convective subcooled boiling flow experiments were conducted in a vertical upward narrow rectangular channel under rolling motion. A high-speed digital video camera was used to capture the dynamics of the bubble nucleation process. Bubble departure diameters were obtained from the images. A bubble departure model based on force balance analysis was proposed to predict the bubble departure size under rolling condition by considering the additional centrifugal, tangential and Coriolis force. The proposed model agreed well with the experimental data within the averaged relative deviation of 5%. (author)

Stabilization of electrohydrodynamic jets by gas discharges and applications to printing

Science.gov (United States)

Korkut, Sibel

From integrated circuits to DNA hybridization micro arrays, many areas of research require flexible and reliable, high resolution surface patterning tools. A new surface patterning technique, electrohydrodynamic printing (EHDP) [1] provides high resolution and speed at the same time, which was not attainable with the existing direct surface patterning techniques. Stability of electrohydrodynamic (EHD) jets determines the accuracy of deployment in EHD printing [1-3]; therefore, understanding non-axisymmetric instability of the jet, which is caused by the surface charges, is crucial to successful operation. In this thesis, fast imaging and image analysis techniques are used to determine non-axisymmetric disturbance growth rates experimentally. Comparison of experimental instability growth rates with the theoretical estimations based on total current reveals a big discrepancy. It is also found that instability growth rates decrease and stability of EHD filaments is enhanced either by decreasing the electrode separation or by changing the surrounding gas. After considering all possible mechanisms, it is concluded that the main reason for stabilization is the increased ionization of the surrounding gas. Gas ionization results in partial neutralization of surface charges on the filament by the oppositely charged ions in the gas phase and stabilizes the jet. A new current balance including the charge transfer through the gas is developed to estimate the charge density left on the filament. Experimental and theoretical instability growth rates agree much better when the estimated charge density is used for the instability growth rate calculations. The second part of the thesis focuses on pattern formation on the surfaces. The final pattern produced with a colloidal suspension by EHDP depends on not only the stability of the jet but also the dynamics of the suspension and the stability of printed lines after the deployment. Rivulet instability, which causes deployed

Rectangular-cladding silicon slot waveguide with improved nonlinear performance

Science.gov (United States)

Huang, Zengzhi; Huang, Qingzhong; Wang, Yi; Xia, Jinsong

2018-04-01

Silicon slot waveguides have great potential in hybrid silicon integration to realize nonlinear optical applications. We propose a rectangular-cladding hybrid silicon slot waveguide. Simulation result shows that, with a rectangular-cladding, the slot waveguide can be formed by narrower silicon strips, so the two-photon absorption (TPA) loss in silicon is decreased. When the cladding material is a nonlinear polymer, the calculated TPA figure of merit (FOMTPA) is 4.4, close to the value of bulk nonlinear polymer of 5.0. This value confirms the good nonlinear performance of rectangular-cladding silicon slot waveguides.

Experimental and Kinetic Modeling Study of Ethyl Levulinate Oxidation in a Jet-Stirred Reactor

KAUST Repository

Wang, Jui-Yang

2017-06-01

A jet-stirred reactor was designed and constructed in the Clean Combustion Research Center (CCRC) at King Abdullah University of Science and Technology (KAUST); was validated with n-heptane, iso-octane oxidation and cyclohexene pyrolysis. Different configurations of the setup have been tested to achieve good agreement with results from the literature. Test results of the reactor indicated that installation of a pumping system at the downstream side in the experimental apparatus was necessary to avoid the reoccurrence of reactions in the sampling probe. Experiments in ethyl levulinate oxidation were conducted in the reactor under several equivalence ratios, from 600 to 1000 K, 1 bar and 2 s residence time. Oxygenated species detected included methyl vinyl ketone, levulinic acid and ethyl acrylate. Ethylene, methane, carbon monoxide, hydrogen, oxygen and carbon dioxide were further quantified with a gas chromatography, coupled with a flame ionization detector and a thermal conductivity detector. The ethyl levulinate chemical kinetic model was first developed by Dr. Stephen Dooley, Trinity College Dublin, and simulated under the same conditions, using the Perfect-Stirred Reactor code in Chemkin software. In comparing the simulation results with experimental data, some discrepancies were noted; predictions of ethylene production were not well matched. The kinetic model was improved by updating several classes of reactions: unimolecular decomposition, H-abstraction, C-C and C-O beta-scissions of fuel radicals. The updated model was then compared again with experimental results and good agreement was achieved, proving that the concerted eliminated reaction is crucial for the kinetic mechanism formulation of ethyl levulinate. In addition, primary reaction pathways and sensitivity analysis were performed to describe the role of molecular structure in combustion (800 and 1000 K for ethyl levulinate oxidation in the jet-stirred reactor).

Experimental studies on transient water-steam impinging jet

International Nuclear Information System (INIS)

Kitade, Kozo; Nakatogawa, Tetsundo; Nishikawa, Hideo; Kawanishi, Kohei; Tsuruto, Chuichi.

1980-01-01

Blowdown experiments were carried out in order to clarify pipe reaction forces and jet forces at hypothetical pipe break accident in PWR. The experiments were carried out at the initial pressure of about 70 and 150 kg/cm 2 .G with subcooling temperature of 13 -- 41 0 C. The reaction force has a maximum value just after the rupture in such a manner to attain abruptly to a peak and gradually decreases after that time in proportion to the inner pressure of the pipe. A plane board was used as a target, on which two-phase flow jet impinged vertically. A distribution of pressure on the target is most wide just after break. On the other hand, the pressure has a maximum value after a short period of time from the rupture. (author)

INTERACTION OF A 24 GeV PROTON BEAM WITH A MUON COLLIDER MERCURY JET TARGET EXPERIMENTAL RESULTS AND THERMODYNAMIC ASSESSMENT

International Nuclear Information System (INIS)

SIMOS, N.; KIRK, H.; FINFROCK, C.; GREENE, G.; LUDEWIG, H.; MCDONALD, K.; MOKHOV, N.

2001-01-01

A muon collider or a neutrino factory based on a muon storage ring require intense beams of muons that can be generated by a 1-4 MW proton beam incident on a moving target inside a 20-T solenoid magnet, with a mercury jet as a preferred example. This paper addresses the thermodynamic interaction of the intense proton beam with the proposed mercury jet target, and the consequences of the generated pressure waves on the target integrity. Specifically, a 24 GeV proton beam with approximately 16 TP (1 TP = 10 12 protons) per pulse and a pulse length of 2 ns will interact with a 1 cm diameter mercury jet within the 20-Tesla magnetic field. In one option, a train of six such proton pulses is to be delivered on target within 2 micros, in which case the state of the mercury jet following the interaction with each pulse is critical. Using the equation of state for mercury from the SESAME library, in combination with the energy deposition rates calculated the by the hadron interaction code MARS, the induced 3-D pressure field in the target is estimated. The consequent pressure wave propagation and attenuation in the mercury jet is calculated using a transient analysis based on finite element modeling, and the state of the mercury jet at the time of arrival of the subsequent pulse is assessed. Issues associated with the use of a liquid metal jet as a target candidate are addressed. Lastly, some experimental results from the BNL E951 experiment are presented and discussed

Magnetohydrodynamic flow of generalized Maxwell fluids in a rectangular micropump under an AC electric field

Energy Technology Data Exchange (ETDEWEB)

Zhao, Guangpu [School of Mathematical Science, Inner Mongolia University, Hohhot, Inner Mongolia 010021 (China); Jian, Yongjun, E-mail: jianyj@imu.edu.cn [School of Mathematical Science, Inner Mongolia University, Hohhot, Inner Mongolia 010021 (China); Chang, Long [School of Mathematics and Statistics, Inner Mongolia University of Finance and Economics, Hohhot, Inner Mongolia 010051 (China); Buren, Mandula [School of Mathematical Science, Inner Mongolia University, Hohhot, Inner Mongolia 010021 (China)

2015-08-01

By using the method of separation of variables, an analytical solution for the magnetohydrodynamic (MHD) flow of the generalized Maxwell fluids under AC electric field through a two-dimensional rectangular micropump is reduced. By the numerical computation, the variations of velocity profiles with the electrical oscillating Reynolds number Re, the Hartmann number Ha, the dimensionless relaxation time De are studied graphically. Further, the comparison with available experimental data and relevant researches is presented. - Highlights: • MHD flow of the generalized Maxwell fluids under AC electric field is analyzed. • The MHD flow is confined to a two-dimensional rectangular micropump. • Analytical solution is obtained by using the method of separation of variables. • The influences of related parameters on the MHD velocity are discussed.

Magnetohydrodynamic flow of generalized Maxwell fluids in a rectangular micropump under an AC electric field

International Nuclear Information System (INIS)

Zhao, Guangpu; Jian, Yongjun; Chang, Long; Buren, Mandula

2015-01-01

By using the method of separation of variables, an analytical solution for the magnetohydrodynamic (MHD) flow of the generalized Maxwell fluids under AC electric field through a two-dimensional rectangular micropump is reduced. By the numerical computation, the variations of velocity profiles with the electrical oscillating Reynolds number Re, the Hartmann number Ha, the dimensionless relaxation time De are studied graphically. Further, the comparison with available experimental data and relevant researches is presented. - Highlights: • MHD flow of the generalized Maxwell fluids under AC electric field is analyzed. • The MHD flow is confined to a two-dimensional rectangular micropump. • Analytical solution is obtained by using the method of separation of variables. • The influences of related parameters on the MHD velocity are discussed

Towards characterizing graphs with a sliceable rectangular dual

NARCIS (Netherlands)

Kusters, V.; Speckmann, B.; Di Giacomo, E.; Lubiw, A.

2015-01-01

Let G be a plane triangulated graph. A rectangular dual of G is a partition of a rectangle R into a set R of interior-disjoint rectangles, one for each vertex, such that two regions are adjacent if and only if the corresponding vertices are connected by an edge. A rectangular dual is sliceable if it

Mechanical behavior analysis on electrostatically actuated rectangular microplates

International Nuclear Information System (INIS)

Li, Zhikang; Zhao, Libo; Jiang, Zhuangde; Ye, Zhiying; Zhao, Yulong; Dai, Lu

2015-01-01

Microplates are widely used in various MEMS devices based on electrostatic actuation such as MEMS switches, micro pumps and capacitive micromachined ultrasonic transducers (CMUTs). Accurate predictions for the mechanical behavior of the microplate under electrostatic force are important not only for the design and optimization of these electrostatic devices but also for their operation. This paper presents a novel reduced-order model for electrostatically actuated rectangular and square microplates with a new method to treat the nonlinear electrostatic force. The model was developed using Galerkin method which turned the partial-differential equation governing the microplates into an ordinary equation system. Using this model and cosine-like deflection functions, explicit expressions were established for the deflection and pull-in voltage of the rectangular and square microplates. The theoretical results were well validated with the finite element method simulations and experimental data of literature. The expressions for the deflection analysis are able to predict the deflection up to the pull-in position with an error less than 5.0%. The expressions for the pull-in voltage analysis can determine the pull-in voltages with errors less than 1.0%. Additionally, the method to calculate the capacitance variation of the electrostatically actuated microplates was proposed. These theoretical analyses are helpful for design and optimization of electrostatically actuated microdevices. (paper)

Forced convective boiling heat transfer of water in vertical rectangular narrow channel

International Nuclear Information System (INIS)

Chen, Chong; Gao, Pu-zhen; Tan, Si-chao; Chen, Han-ying; Chen, Xian-bing

2015-01-01

Highlights: • Chen correlation cannot well predict the coefficient of rectangular channel. • Kim and Mudawar correlation is the best one among the Chen type correlations. • Lazarek and Black correlation predicted 7.0% of data within the ±30% error band. • The new correlation can well predict the coefficient with a small MAE of 14.4%. - Abstract: In order to research the characteristics of boiling flows in a vertical rectangular narrow channel, a series of convective boiling heat transfer experiments are performed. The test section is made of stainless steel with an inner diameter of 2 × 40 mm and heated length of 1100 mm. The 3194 experimental data points are obtained for a heat flux range of 10–700 kW/m 2 , a mass flux range of 200–2400 kg/m 2 s, a system pressure range of 0.1–2.5 MPa, and a quality range of 0–0.8. Eighteen prediction models are used to predict the flow boiling heat transfer coefficient of the rectangular narrow channel and the predicted value is compared against the database including 3194 data points, the results show that Chen type correlations and Lazarek and Black type correlations are not suitable for the rectangular channel very much. The Kim and Mudawar correlation is the best one among the 18 models. A new correlation is developed based on the superposition concept of nucleate boiling and convective boiling. the new correlation is shown to provide a good prediction against the database, evidenced by an overall MAE of 14.4%, with 95.2% and 98.6% of the data falling within ±30% and ±35% error bands, respectively

Transverse jets and their control

Energy Technology Data Exchange (ETDEWEB)

Karagozian, Ann R. [Department of Mechanical and Aerospace Engineering, University of California, 48-121 Engineering IV, Los Angeles, CA 90095 (United States)

2010-10-15

The jet in crossflow or transverse jet has been studied extensively because of its relevance to a wide variety of flows in technological systems, including fuel or dilution air injection in gas turbine engines, thrust vector control for high speed airbreathing and rocket vehicles, and exhaust plumes from power plants. These widespread applications have led over the past 50+ years to experimental, theoretical, and numerical examinations of this fundamental flowfield, with and without a combustion reaction, and with single or multi-phase flow. The complexities in this flowfield, whether the jet is introduced flush with respect to the injection wall or from an elevated pipe or nozzle, present challenges in accurately interrogating, analyzing, and simulating important jet features. This review article provides a background on these studies and applications as well as detailed features of the transverse jet, and mechanisms for its control via active means. Promising future directions for the understanding, interrogation, simulation, and control of transverse jet flows are also identified and discussed. (author)

Numerical Calculation of Interaction Between Plane Jet and Subsonic Flow

Directory of Open Access Journals (Sweden)

V. O. Moskalenko

2016-01-01

Full Text Available The paper makes numerical calculation of interaction between plane jet and subsonic flow. Its aim is to determine the jet trajectory, velocity profiles, distribution of pressure coefficient on the plate surface at different jet angles, namely ωj=45°; 90°; 105° and at low blowing strengths ( ≤1.5 as well as a to make comparison with the experimental data of other authors.To simulate a two-dimensional jet in the subsonic flow the software package “CAD SolidWorks Flow Simulation” has been used. Initially, the test task was solved with its calculation results compared with experimental ones [6.8] in order to improve the convergence; the size of the computational domain and a computational grid within the k-ε turbulence model were selected. As a result of the calculation, were identified and analysed the pressure values, jet trajectories, and velocity profiles. In the graphs the solid lines show calculation results, and dots represent experimental data.From the calculation results it is seen that, with increasing intensity of the reduced mass flow ¯q in the above range, the change of the jet pressure coefficient p¯ distribution behind a slotted nozzle is almost linear and significant. Before the nozzle, with increasing ¯q the pressure coefficient increases slightly.Analysis of results has shown that blowing of jets with ωj>90ω, provides a greater perturbation of the subsonic flow. Thus, the jet penetrates into the flow deeper, forms a dead region of the greater length, and more significantly redistributes the pressure coefficient on the surface of the plate.The calculation results are in good compliance with the experimental data both for the jet axis and for the pressure coefficient distribution on the plate surface. The research results can be used in the designing the jet control of aircrafts.

Experimental simulation of lightning, interacting explosions and astrophysical jets with pulsed lasers

International Nuclear Information System (INIS)

Villagran-Muniz, M; Sobral, H; Navarro-Gonzalez, R; Velazquez, P F; Raga, A C

2003-01-01

Tabletop laboratory experiments have been used to simulate natural lightning, interacting explosions and astrophysical jets. When a high-energy laser pulse is focused in air, a laser-induced plasma (LIP) is produced, that generates a shock wave and an adiabatic expansion of the gas. In our work we have used LIPs in order to simulate lightning, for the study of chemical reactions relevant to atmospheric science. Several diagnostics have been applied to our LIPs, such as deflectometry, shadowgraphy and interferometry, which yield full spatial information of the process (electron density and temperature, the position of the shock wave fronts and the expansion of the hot gas), with a time resolution that ranges from nanoseconds to milliseconds. A new diagnostic alternative was implemented for shadowgraphy, which uses either continuous lasers or conventional light sources. The experimental results have been reproduced by hydrodynamic codes that we have developed. With astrophysical applications in mind, we have simulated and diagnosed the interaction of two explosions, with the aforementioned techniques. For this purpose, two LIPs are synchronized and diagnosed spatially and temporarily. Also, by producing the LIP in a glass sphere with a nozzle that ejects a shock wave and hot gas, we are able to simulate astrophysical jets. With such experiments, astrophysical models developed by us have been validated, showing excellent agreement between experiments and numerical simulations

JET Joint Undertaking

International Nuclear Information System (INIS)

Keen, B.E.; Kupschus, P.

1984-09-01

The report is in sections, as follows. (1) Introduction and summary. (2) A brief description of the origins of the JET Project within the EURATOM fusion programme and the objectives and aims of the device. The basic JET design and the overall philosophy of operation are explained and the first six months of operation of the machine are summarised. The Project Team Structure adopted for the Operation Phase is set out. Finally, in order to set JET's progress in context, other large tokamaks throughout the world and their achievements are briefly described. (3) The activities and progress within the Operation and Development Department are set out; particularly relating to its responsibilities for the operation and maintenance of the tokamak and for developing the necessary engineering equipment to enhance the machine to full performance. (4) The activities and progress within the Scientific Department are described; particularly relating to the specification, procurement and operation of diagnostic equipment; definition and execution of the programme; and the interpretation of experimental results. (5) JET's programme plans for the immediate future and a broad outline of the JET Development Plan to 1990 are given. (author)

An experimental investigation on the velocity fluctuation characteristics in a triple air jet

International Nuclear Information System (INIS)

Nam, Ho Yun; Kim, Jong Man; Choi, Jong Hyeon; Choi, Seok Ki

2005-01-01

The thermal striping which occurs due to a turbulent thermal mixing in the upper plenum of a liquid metal reactor causes a temperature fluctuation on the adjacent solid materials and it is an important parameter in the design of a liquid metal reactor. An experimental apparatus which is a mock up of the fuel assembly in the liquid metal reactor is devised, and the average velocity and the velocity fluctuation in a two-dimensional jet from three nozzles are measured. In the present paper the characteristics of the velocity fluctuation which is used for a validation of a thermal hydraulic computer code is described

Computational and experimental characterization of a liquid jet plunging into a quiescent pool at shallow inclination

International Nuclear Information System (INIS)

Deshpande, Suraj S.; Trujillo, Mario F.; Wu Xiongjun; Chahine, Georges

2012-01-01

Highlights: ► Jet impingement at shallow angles results in periodic cavity formation. ► Velocity profile affected both by buoyancy and splashing in the near field. ► Momentum diffusion leads to a velocity maximum at the gas–liquid interface for the far field. - Abstract: A circular water jet (Re = 1.6 × 10 5 ; We = 8.8 × 10 3 ) plunging at shallow angles (θ ≈ 12.5°) into a quiescent pool is investigated computationally and experimentally. A surprising finding from the work is that cavities, of the order of jet diameter, are formed periodically in the impact location, even though the impinging flow is smooth and completely devoid of such a periodicity. Computational prediction of these frequencies was compared with experimental findings, yielding excellent agreement. The region in the vicinity of the impact is characterized by strong churning due to splashing and formation of air cavities. Measured velocity profiles indicate a concentration of momentum beneath the free surface slightly beyond the impact location (X/D j ≈ 14), with a subsequent shift towards the free surface further downstream of this point (X/D j ≈ 30). This shift is due primarily to the action of buoyancy on the cavity/bubble population. Comparisons of the mean velocity profile between simulations and experiments are performed, yielding good agreement, with the exception of the relatively small churning flow region. Further downstream (X/D j ≳ 40), the flow develops mostly due to diffusion and the location of peak velocity coincides with the free surface. In this region, the free surface acts as an adiabatic boundary and restricts momentum diffusion, causing the peak velocity to occur at the free surface.

Associated jet production at HERA

CERN Document Server

Bartels, Julius; de Roeck, A; Graudenz, Dirk; Wüsthoff, M

1996-01-01

We compare the BFKL prediction for the associated production of forward jets at HERA with fixed-order matrix element calculations taking into account the kinematical cuts imposed by experimental conditions. Comparison with H1 data of the 1993 run favours the BFKL prediction. As a further signal of BFKL dynamics, we propose to look for the azimuthal dependence of the forward jets.

Scour process caused by multiple subvertical non-crossing jets

Directory of Open Access Journals (Sweden)

Stefano Pagliara

2017-01-01

Full Text Available The scour process induced by plunging jets is an important topic for hydraulic engineers. In recent decades, several researchers have developed new strategies and methodologies to control the scour morphology, including different jet arrangements and structures located in the stilling basin. It has been found that multiple jets can cause less scouring than single plunging jets. Based on this evidence, this study aimed to investigate the equilibrium morphology caused by multiple non-crossing jets. A dedicated laboratory model was built and experimental tests were carried out under different combinations of jet inclination angles, by varying the tailwater level and the virtual crossing point location, which was set below the original channel bed level. It was experimentally shown that the equilibrium scour morphology depends on the jet discharge, the differences in non-crossing jet inclination angles, the downstream water level, and the distance of the virtual crossing point from the original channel bed level. In particular, the last parameter was found to be one of the most influential parameters, because of the resulting flow patterns inside the water body. Furthermore, the analysis of experimental evidence allowed for a complete and detailed classification of the scour hole typologies. Three different scour typologies were distinguished and classified. Finally, based on previous studies, two novel relationships have been proposed to predict both the maximum scour depth and length within a large range of hydraulic and geometric parameters.

Experimental and numerical investigations of the impingement of an oblique liquid jet onto a superhydrophobic surface: energy transformation

Energy Technology Data Exchange (ETDEWEB)

Kibar, Ali, E-mail: alikibar@kocaeli.edu.tr [Department of Mechanical and Material Technologies, Kocaeli University, 41285, Arslanbey Campus, Kocaeli (Turkey)

2016-02-15

This study presents the theory of impinging an oblique liquid jet onto a vertical superhydrophobic surface based on both experimental and numerical results. A Brassica oleracea leaf with a 160° apparent contact angle was used for the superhydrophobic surface. Distilled water was sent onto the vertical superhydrophobic surface in the range of 1750–3050 Reynolds number, with an inclination angle of 20°−40°, using a circular glass tube with a 1.75 mm inner diameter. The impinging liquid jet spread onto the surface governed by the inertia of the liquid and then reflected off the superhydrophobic surface due to the surface energy of the spreading liquid. Two different energy approaches, which have time-scale and per-unit length, were performed to determine transformation of the energy. The kinetic energy of the impinging liquid jet was transformed into the surface energy with an increasing interfacial surface area between the liquid and air during spreading. Afterwards, this surface energy of the spreading liquid was transformed into the reflection kinetic energy. (paper)

Droplet size in a rectangular Venturi scrubber

Directory of Open Access Journals (Sweden)

M. A. M. Costa

2004-06-01

Full Text Available The Venturi scrubber is a device which uses liquid in the form of droplets to efficiently remove fine particulate matter from gaseous streams. Droplet size is of fundamental importance for the scrubber performance. In the present experimental study, a laser diffraction technique was used in order to measure droplet size in situ in a Venturi scrubber with a rectangular cross section. Droplet size distribution was measured as a function of gas velocity (58.3 to 74.9 m/s, liquid-to-gas ratio (0.07 to 0.27 l/m³, and distance from liquid injection point (64 to 173 mm. It was found that all these variables significantly affect droplet size. The results were compared with the predictions from correlations found in the literature.

Numerical and experimental study of blowing jet on a high lift airfoil

Science.gov (United States)

Bobonea, A.; Pricop, M. V.

2013-10-01

Active manipulation of separated flows over airfoils at moderate and high angles of attack in order to improve efficiency or performance has been the focus of a number of numerical and experimental investigations for many years. One of the main methods used in active flow control is the usage of blowing devices with constant and pulsed blowing. Through CFD simulation over a 2D high-lift airfoil, this study is trying to highlight the impact of pulsed blowing over its aerodynamic characteristics. The available wind tunnel data from INCAS low speed facility are also beneficial for the validation of the numerical analysis. This study intends to analyze the impact of the blowing jet velocity and slot geometry on the efficiency of an active flow control.

Jet observables without jet algorithms

Energy Technology Data Exchange (ETDEWEB)

Bertolini, Daniele; Chan, Tucker; Thaler, Jesse [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States)

2014-04-02

We introduce a new class of event shapes to characterize the jet-like structure of an event. Like traditional event shapes, our observables are infrared/collinear safe and involve a sum over all hadrons in an event, but like a jet clustering algorithm, they incorporate a jet radius parameter and a transverse momentum cut. Three of the ubiquitous jet-based observables — jet multiplicity, summed scalar transverse momentum, and missing transverse momentum — have event shape counterparts that are closely correlated with their jet-based cousins. Due to their “local” computational structure, these jet-like event shapes could potentially be used for trigger-level event selection at the LHC. Intriguingly, the jet multiplicity event shape typically takes on non-integer values, highlighting the inherent ambiguity in defining jets. By inverting jet multiplicity, we show how to characterize the transverse momentum of the n-th hardest jet without actually finding the constituents of that jet. Since many physics applications do require knowledge about the jet constituents, we also build a hybrid event shape that incorporates (local) jet clustering information. As a straightforward application of our general technique, we derive an event-shape version of jet trimming, allowing event-wide jet grooming without explicit jet identification. Finally, we briefly mention possible applications of our method for jet substructure studies.

The jet membrane-experiment: downstream sampling

International Nuclear Information System (INIS)

Campargue, R.

1976-01-01

The invasion separation effect of the free jet structure was found in 1966 at Saclay. In the Downstream Sampling Configuration patended by Campargue (1967), the light fraction is withdrawn from the supersonic central core, by skimming the separating free jet. From experimental and theoretical results obtained for gas and isotopic mixtures, the following points linked to operation and equipment costs, are considered: system description; influence of mass ratio, expansion ratio, nature of separating gas, ratio of upflow to separating jet flow, rarefaction. Fron an uninteresting aspect of Jet Membrane (elimination of background penetration), a new principle has been discovered to produce nozzle beams which may be of great interest for other separation processes involving free jets and/or molecular beams [fr

Design of experimental setup for supercritical CO2 jet under high ambient pressure conditions

Science.gov (United States)

Shi, Huaizhong; Li, Gensheng; He, Zhenguo; Wang, Haizhu; Zhang, Shikun

2016-12-01

With the commercial extraction of hydrocarbons in shale and tight reservoirs, efficient methods are needed to accelerate developing process. Supercritical CO2 (SC-CO2) jet has been considered as a potential way due to its unique fluid properties. In this article, a new setup is designed for laboratory experiment to research the SC-CO2 jet's characteristics in different jet temperatures, pressures, standoff distances, ambient pressures, etc. The setup is composed of five modules, including SC-CO2 generation system, pure SC-CO2 jet system, abrasive SC-CO2 jet system, CO2 recovery system, and data acquisition system. Now, a series of rock perforating (or case cutting) experiments have been successfully conducted using the setup about pure and abrasive SC-CO2 jet, and the results have proven the great perforating efficiency of SC-CO2 jet and the applications of this setup.

Properties of Supersonic Impinging Jets

Science.gov (United States)

Alvi, F. S.; Iyer, K. G.; Ladd, J.

1999-11-01

A detailed study examining the behavior of axisymmetric supersonic jets impinging on a ground plane is described. Our objective is to better understand the aeroacoustics governing this complex flowfield which commonly occurs in the vicinity of STOVL aircraft. Flow issuing through a Mach 1.5 C-D and a converging sonic nozzle is examined over a wide parametric range. For some cases a large diameter circular 'lift' plate, with an annular hole through which the jet is issued, is attached at the nozzle exit to simulate a generic airframe. The impinging jet flowfield was examined using Particle Image Velocimetry (PIV), which provides the velocity field for the entire region and shadowgraph visualization techniques. Near-field acoustic, as well as, mean and unsteady pressure measurements on the ground and lift plate surfaces were also obtained. The velocity field data, together with the surface flow measurements have resulted in a much better understanding of this flow from a fundamental standpoint while also identifying critical regions of interest for practical applications. Some of these findings include the presence of a stagnation bubble with recirculating flow; a very high speed (transonic/supersonic) radial wall jet; presence of large, spatially coherent turbulent structures in the primary jet and wall jet and high unsteady loads on the ground plane and lift plates. The results of a companion CFD investigation and its comparison to the experimental data will also be presented. Very good agreement has been found between the computational and experimental results thus providing confidence in the development of computational tools for the study of such flows.

A computational study of highly viscous impinging jets

Energy Technology Data Exchange (ETDEWEB)

Silva, M.W. [Univ. of Texas, Austin, TX (United States). Dept. of Mechanical Engineering

1998-11-01

Two commercially-available computational fluid dynamics codes, FIDAP (Fluent, Inc., Lebanon, NH) and FLOW-3D (Flow Science, Inc., Los Alamos, NM), were used to simulate the landing region of jets of highly viscous fluids impinging on flat surfaces. The volume-of-fluid method was combined with finite difference and finite element approaches to predict the jet behavior. Several computational models with varying degrees of physical realism were developed, and the results were compared with experimental observations. In experiments, the jet exhibited several complex behaviors. As soon as it exited the nozzle, the jet began to neck down and become narrower. When it impacted the solid surface, the jet developed an instability near the impact point and buckled to the side. This buckling became a spiraling motion, and the jet spiraled about the impact point. As the jet spiraled around, a cone-shaped pile was build up which eventually became unstable and slumped to the side. While all of these behaviors were occurring, air bubbles, or voids, were being entrapped in the fluid pool. The results obtained from the FLOW-3D models more closely matched the behavior of real jets than the results obtained from /the FIDAP models. Most of the FLOW-3D models predicted all of the significant jet behaviors observed in experiments: necking, buckling, spiraling, slumping, and void entrapment. All of the FIDAP models predicted that the jet would buckle relatively far from the point of impact, whereas the experimentally observed jet behavior indicates that the jets buckle much nearer the impact point. Furthermore, it was shown that FIDAP is incapable of incorporating heat transfer effects into the model, making it unsuitable for this work.

A computational study of highly viscous impinging jets

International Nuclear Information System (INIS)

Silva, M.W.

1998-11-01

Two commercially-available computational fluid dynamics codes, FIDAP (Fluent, Inc., Lebanon, NH) and FLOW-3D (Flow Science, Inc., Los Alamos, NM), were used to simulate the landing region of jets of highly viscous fluids impinging on flat surfaces. The volume-of-fluid method was combined with finite difference and finite element approaches to predict the jet behavior. Several computational models with varying degrees of physical realism were developed, and the results were compared with experimental observations. In experiments, the jet exhibited several complex behaviors. As soon as it exited the nozzle, the jet began to neck down and become narrower. When it impacted the solid surface, the jet developed an instability near the impact point and buckled to the side. This buckling became a spiraling motion, and the jet spiraled about the impact point. As the jet spiraled around, a cone-shaped pile was build up which eventually became unstable and slumped to the side. While all of these behaviors were occurring, air bubbles, or voids, were being entrapped in the fluid pool. The results obtained from the FLOW-3D models more closely matched the behavior of real jets than the results obtained from /the FIDAP models. Most of the FLOW-3D models predicted all of the significant jet behaviors observed in experiments: necking, buckling, spiraling, slumping, and void entrapment. All of the FIDAP models predicted that the jet would buckle relatively far from the point of impact, whereas the experimentally observed jet behavior indicates that the jets buckle much nearer the impact point. Furthermore, it was shown that FIDAP is incapable of incorporating heat transfer effects into the model, making it unsuitable for this work

Analysis of High Tc Superconducting Rectangular Microstrip Patches over Ground Planes with Rectangular Apertures in Substrates Containing Anisotropic Materials

Directory of Open Access Journals (Sweden)

Abderraouf Messai

2013-01-01

Full Text Available A rigorous full-wave analysis of high Tc superconducting rectangular microstrip patch over ground plane with rectangular aperture in the case where the patch is printed on a uniaxially anisotropic substrate material is presented. The dyadic Green’s functions of the considered structure are efficiently determined in the vector Fourier transform domain. The effect of the superconductivity of the patch is taken into account using the concept of the complex resistive boundary condition. The accuracy of the analysis is tested by comparing the computed results with measurements and previously published data for several anisotropic substrate materials. Numerical results showing variation of the resonant frequency and the quality factor of the superconducting antenna with regard to operating temperature are given. Finally, the effects of uniaxial anisotropy in the substrate on the resonant frequencies of different TM modes of the superconducting microstrip antenna with rectangular aperture in the ground plane are presented.

Jet Joint Undertaking. Vol. 2

International Nuclear Information System (INIS)

1989-06-01

The scientific, technical, experimental and theoretical investigations related to JET tokamak are presented. The JET Joint Undertaking, Volume 2, includes papers presented at: the 15th European Conference on controlled fusion and plasma heating, the 15th Symposium on fusion technology, the 12th IAEA Conference on plasma physics and controlled nuclear fusion research, the 8th Topical Meeting on technology of fusion. Moreover, the following topics, concerning JET, are discussed: experience with wall materials, plasma performance, high power ion cyclotron resonance heating, plasma boundary, results and prospects for fusion, preparation for D-T operation, active gas handling system and remote handling equipment

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

Experimental results from magnetized-jet experiments executed at the Jupiter Laser Facility

Science.gov (United States)

Manuel, M. J.-E.; Kuranz, C. C.; Rasmus, A. M.; Klein, S. R.; MacDonald, M. J.; Trantham, M. R.; Fein, J. R.; Belancourt, P. X.; Young, R. P.; Keiter, P. A.; Drake, R. P.; Pollock, B. B.; Park, J.; Hazi, A. U.; Williams, G. J.; Chen, H.

2015-12-01

Recent experiments at the Jupiter Laser Facility investigated magnetization effects on collimated plasma jets. Laser-irradiated plastic-cone-targets produced collimated, millimeter-scale plasma flows as indicated by optical interferometry. Proton radiography of these jets showed no indication of strong, self-generated magnetic fields, suggesting a dominantly hydrodynamic collimating mechanism. Targets were placed in a custom-designed solenoid capable of generating field strengths up to 5 T. Proton radiographs of the well-characterized B-field, without a plasma jet, suggested an external source of trapped electrons that affects proton trajectories. The background magnetic field was aligned with the jet propagation direction, as is the case in many astrophysical systems. Optical interferometry showed that magnetization of the plasma results in disruption of the collimated flow and instead produces a hollow cavity. This result is a topic of ongoing investigation.

Theoretical Analysis and Experimental Study on the Coating Removal from Passenger-Vehicle Plastics for Recycling by Using Water Jet Technology

Science.gov (United States)

Zhang, Hongshen; Chen, Ming

2015-11-01

The recovery and utilization of automotive plastics are a global concern because of the increasing number of end-of-life vehicles. In-depth studies on technologies for the removal of coatings from automotive plastics can contribute to the high value-added levels of the recycling and utilization of automotive plastic. The liquid waste generated by removing chemical paint by using traditional methods is difficult to handle and readily produces secondary pollution. Therefore, new, clean, and highly efficient techniques of paint removal must be developed. In this article, a method of coating removal from passenger-vehicle plastics was generated based on high-pressure water jet technology to facilitate the recycling of these plastics. The established technology was theoretically analyzed, numerically simulated, and experimentally studied. The high-pressure water jet equipment for the removal of automotive-plastic coatings was constructed through research and testing, and the detailed experiments on coating removal rate were performed by using this equipment. The results showed that high-pressure water jet technology can effectively remove coatings on the surfaces of passenger-vehicle plastics. The research also revealed that the coating removal rate increased as jet pressure ( P) increased and then decreased when jet moving speed ( Vn) increased. The rate decreased as the distance from nozzle to work piece ( S nw ) and the nozzle angle ( Φ) increased. The mathematical model for the rate of removal of coatings from bumper surfaces by water jet was derived based on the experiment data and can effectively predict coating removal rate under different operating conditions.

Fully developed liquid-metal flow in multiple rectangular ducts in a strong uniform magnetic field

International Nuclear Information System (INIS)

Molokov, S.

1993-01-01

Fully developed liquid-metal flow in a straight rectangular duct with thin conducting walls is investigated. The duct is divided into a number of rectangular channels by electrically conducting dividing walls. A strong uniform magnetic field is applied parallel to the outer side walls and dividing walls and perpendicular to the top and the bottom walls. The analysis of the flow is performed by means of matched asymptotics at large values of the Hartmann number M. The asymptotic solution obtained is valid for arbitrary wall conductance ratio of the side walls and dividing walls, provided the top and bottom walls are much better conductors than the Hartmann layers. The influence of the Hartmann number, wall conductance ratio, number of channels and duct geometry on pressure losses and flow distribution is investigated. If the Hartmann number is high, the volume flux is carried by the core, occupying the bulk of the fluid and by thin layers with thickness of order M -1/2 . In some of the layers, however, the flow is reversed. As the number of channels increases the flow in the channels close to the centre approaches a Hartmann-type flow with no jets at the side walls. Estimation of pressure-drop increase in radial ducts of a self-cooled liquid-metal blanket with respect to flow in a single duct with walls of the same wall conductance ratio gives an upper limit of 30%. (author). 13 refs., 10 figs., 1 tab

Study on the output factors of asymmetrical rectangular electron beam field

International Nuclear Information System (INIS)

Chen Yinghai; Yang Yueqin; Ma Yuhong; Zheng Jin; Zou Lijuan

2009-01-01

Objective: To evaluate the variant regularity of the output factors of asymmetrical rectangular electron beam field. Methods: The output factors of three special fields with different applicators and energies were measured by ionization chamber method at different off-axis distances. Then deviations of the output factors between asymmetrical and symmetric rectangular fields were calculated. Results: The changes of output factor with different off-axis distances in asymmetrical rectangular fields were basically consistent with those in standard square fields with the same applicator. It revealed that the output factor of asymmetrical rectangular field was related with the off-axis ratio of standard square field. Applicator and field size did not show obvious influence on the output factor. Conclusions: The output factor changes of asymmetrical rectangular field are mainly correlated with the off-axis ratio of standard square field. The correction of the output factor is determined by the off-axis ratio changes in standard square field. (authors)

Numerical and experimental study on laminar round free jet of Ar discharging into stagnant air

International Nuclear Information System (INIS)

Fumizawa, Motoo; Hishida, Makoto; Kunugi, Tomoaki

1990-01-01

The objective of the present study is to investigate numerically and experimentally the behavior of the fluid flow and the mass transfer of argon gas (Ar) laminar round jet discharging into stagnant air along the gravity force. The SIMPLE method and two differential numerical schemes of PLDS and QUICK are used in the TEAM code modified by adding the binary diffusion equation. The solution domain is comprised of 80X40 grids of uniform size. As the result, the following were obtained: The half radius of Ar mass fraction obtained by QUICK was in good agreement with experimental result. The half radii of axial velocity and Ar mass fraction obtained by PLDS were larger than those by QUICK due to numerical viscosity. Numerical analyses by PLDS and QUICK schemes agreed well with experimental results on centerline Ar mass fraction. Computational times of PLDS and QUICK are about 40 min. and 120 min. respectively by FACOM VP100 computer in JAERI. (author)

Very forward jet, Mueller Navelet jets and jet gap jet measurements in CMS

CERN Document Server

Cerci, Salim

2018-01-01

The measurements of very forward jet, Mueller-Navelet jets and jet-gap-jet events are presented for different collision energies. The analyses are based on data collected with the CMS detector at the LHC. Jets are defined through the anti-$k_\\mathrm{t}$ clustering algorithm for different cone sizes. Jet production studies provide stringent tests of quantum chromodynamics (QCD) and contribute to tune Monte Carlo (MC) simulations and phenomenological models. The measurements are compared to predictions from various Monte Carlo event generators.

Computational study of jet interaction flow field with and without incidence

International Nuclear Information System (INIS)

Asif, M.; Zahir, S.; Khan, M.A.

2004-01-01

The objective was to study the interaction of a side jet with the incoming supersonic flow and hypersonic flow. Qualitatively same Cp trends have been obtained as found experimentally. Also in aerodynamic coefficients side jet interaction results in additional pitching moment which is because of the high pressure region in upstream of the jet and a low pressure region in the downstream of the jet. Also jet interaction results in the rise in the lift coefficient. Whereas in the incidence case, simulation has been performed for the hypersonic flows over a biconic body with supersonic lateral jet at Mach 9.7 and incidence of 0 o to incidence of -12 o and 12 o . The results obtained were compared with the experimental and CFD code CFL3D results. PAK-3D over predicts the surface pressure as compared to the CFL3D and experimental results, whereas the qualitative trends are the same. Finally the integrated aerodynamic force coefficients were compared with CFL3D predicted results. (author)

A Characterization of Rectangular Distributions

OpenAIRE

Terrell, George R.

1983-01-01

It is well known that the smaller and the larger of a random sample of size two are positively correlated. The coefficient of correlation is at most one-half, and the upper bound is attained only for rectangular distributions.

Study of fuel powder formation in reactive coaxial jets; Etude de la formation de poudre dans des jets coaxiaux reactifs

Energy Technology Data Exchange (ETDEWEB)

Ablitzer, C

1999-11-09

One step of the conversion of gaseous UF{sub 6} to solid UO{sub 2} by dry route is the formation of particles of UO{sub 2}F{sub 2} in a triple coaxial jet UF{sub 6}/N{sub 2}/H{sub 2}O. The characteristics of resulting powder have an influence on the properties of final particles of UO{sub 2}, and then on the quality of pellets of nuclear fuel. So a good control of this step of the process is of interest. This study deals with an experimental investigation and modelling of the influence of various parameters on particles obtained by reaction in a turbulent coaxial jet. For example, the influence of absolute and relative velocities of gases on particle size distributions has been investigated. Two kinds of experimental studies have been undertaken. First, the development of mixing layers in the near field of the jet has been evaluated with temperature measurements. Then, particle size distributions have been measured with e turbidimetric sensor, for particles obtained by hydrolysis of gaseous metallic chlorides (SnCl{sub 4}, TiCl{sub 4}) in double and triple coaxial jets. A model has been proposed for mixing of gases and growth of particles. It takes into account the development of mixing layers, meso-mixing, micro-mixing and growth of particles through agglomeration. The influence of operating parameters, especially velocities, on experimental results appear to be different for TiCl{sub 4}/H{sub 2}O jets and SnCl{sub 4}/H{sub 2}O jets. In fact, a comparison of theoretical and experimental results shows that particles obtained by hydrolysis of TiCl{sub 4} seem to grow mainly through agglomeration whereas another growth phenomenon may be involved for particles obtained by hydrolysis of SnCl{sub 4}. (authors)

Experimental investigation of a reacting transverse jet in a high pressure oscillating vitiated crossflow

Science.gov (United States)

Fugger, Christopher A.

Staged combustion is one design approach in a gas turbine engine to reduce pollutant emission levels. In axially staged combustion, portions of the air and fuel are injected downstream of a lean premixed low NOx primary combustion zone. The gas residence time at elevated temperatures is decreased resulting in lower thermal NOx, and the reduced oxygen and high temperature vitiated primary zone flow further help to reduce pollutant emissions and quickly complete combustion. One implementation of axially staged combustion is transverse fuel jet injection. An important consideration for staged combustion systems, though, is how the primary and secondary combustion zones can couple through the acoustic resonances of the chamber. These couplings can lead to additional source terms that pump energy into the resonant acoustic field and help sustain the high-amplitude combustor pressure oscillations. An understanding of these couplings is important so that it may be possible to design a secondary combustion system that provides inherent damping to the combustor system. To systematically characterize the coupling of a reacting jet in unsteady crossflow in detail, the effects of an an unsteady pressure flowfield and an unsteady velocity flowfield are separately investigated. An optically accessible resonant combustion chamber was designed and built as part of this work to generate a standing wave unsteady vitiated crossflow at a chamber pressure of 0.9 MPa. The location of transverse jet injection corresponds to one of two locations, where one location is the pressure node and the other location the pressure anti-node of the resonant chamber acoustic mode. The injection location is optically accessible, and the dynamic interactions between the transverse jet flow and the 1st and 2nd axial combustor modes are measured using 10 kHz OH-PLIF and 2D PIV. This document analyzes five test cases: two non-reacting jets and three reacting jets. All cases correspond to jet injection

Method and structure for cache aware transposition via rectangular subsections

Science.gov (United States)

Gustavson, Fred Gehrung; Gunnels, John A

2014-02-04

A method and structure for transposing a rectangular matrix A in a computer includes subdividing the rectangular matrix A into one or more square submatrices and executing an in-place transposition for each of the square submatrices A.sub.ij.

Free vibration characteristics analysis of rectangular plate with rectangular opening based on Fourier series method

Directory of Open Access Journals (Sweden)

WANG Minhao

2017-08-01

Full Text Available Plate structures with openings are common in many engineering structures. The study of the vibration characteristics of such structures is directly related to the vibration reduction, noise reduction and stability analysis of an overall structure. This paper conducts research into the free vibration characteristics of a thin elastic plate with a rectangular opening parallel to the plate in an arbitrary position. We use the improved Fourier series to represent the displacement tolerance function of the rectangular plate with an opening. We can divide the plate into an eight zone plate to simplify the calculation. We then use linear springs, which are uniformly distributed along the boundary, to simulate the classical boundary conditions and the boundary conditions of the boundaries between the regions. According to the energy functional and variational method, we can obtain the overall energy functional. We can also obtain the generalized eigenvalue matrix equation by studying the extremum of the unknown improved Fourier series expansion coefficients. We can then obtain the natural frequencies and corresponding vibration modes of the rectangular plate with an opening by solving the equation. We then compare the calculated results with the finite element method to verify the accuracy and effectiveness of the method proposed in this paper. Finally, we research the influence of the boundary condition, opening size and opening position on the vibration characteristics of a plate with an opening. This provides a theoretical reference for practical engineering application.

Plasma jet source parameter optimisation and experiments on injection into Globus-M spherical tokamak

International Nuclear Information System (INIS)

Gusev, V.K.; Petrov, Yu.V.; Sakharov, N.V.; Semenov, A.A.; Voronin, A.V.

2005-01-01

Results of theoretical and experimental research on the plasma sources and injection of plasma and gas jet produced by the modified source into tokamak Globus-M are presented. An experimental test stand was developed for investigation of intense plasma jet generation. Optimisation of pulsed coaxial accelerator parameters by means of analytical calculations is performed with the aim of achieving the highest flow velocity at limited coaxial electrode length and discharge current. The optimal parameters of power supply to generate a plasma jet with minimal impurity contamination and maximum flow velocity were determined. A comparison of experimental and calculation results is made. Plasma jet parameters are measured, such as: impurity species content, pressure distribution across the jet, flow velocity, plasma density, etc. Experiments on the interaction of a higher kinetic energy plasma jet with the magnetic field and plasma of the Globus-M tokamak were performed. Experimental results on plasma and gas jet injection into different Globus-M discharge phases are presented and discussed. Results are presented on the investigation of plasma jet injection as the source for discharge breakdown, plasma current startup and initial density rise. (author)

Performance of jet impingement in unglazed air collectors

Energy Technology Data Exchange (ETDEWEB)

Belusko, M.; Saman, W.; Bruno, F. [Institute for Sustainable Systems and Technologies, University of South Australia, Mawson Lakes Boulevard, Mawson Lakes, SA 5095 (Australia)

2008-05-15

Jet impingement is effective at improving the heat transfer between air and a heated surface. Studies have shown that jet impingement can marginally improve the thermal efficiency of a glazed collector. However, little attention has been placed on applying jet impingement to an unglazed solar air collector. This paper presents a theoretical and experimental investigation identifying the performance characteristics of jet impingement. Overall, jet impingement was able to improve the thermal efficiency of the collector by 21%. An increase in the pressure loss was also measured but found to be small. The flow distribution of jets along the collector was the most significant factor in determining the efficiency. Increasing the hole spacing was found to improve the efficiency. (author)

Effect of void fraction correlations on two-phase pressure drop during flow boiling in narrow rectangular channel

International Nuclear Information System (INIS)

Huang, Dong; Gao, Puzhen; Chen, Chong; Lan, Shu

2013-01-01

Highlights: • Most of the slip ratio models and the Lockhart–Martinelli parameter based models give similar results. • The drift flux void fraction models give relatively small values. • The effect of void fraction correlations on two-phase friction pressure drop is inconspicuous. • The effect of void fraction correlations on two-phase acceleration pressure drop is significant. - Abstract: The void fraction of water during flow boiling in vertical narrow rectangular channel is experimentally investigated. The void fraction is indirectly determined using the present experimental data with various void fraction correlations or models published in the open literature. The effects of mass flux, mass quality, system pressure and inlet subcooling on the void fraction and pressure drop are discussed in detail. In addition, comparison and discussion among the numerous void fraction correlations are carried out. The effect of void fraction correlations on two-phase pressure drop is presented as well. The results reveal that most of the slip ratio correlations and the Lockhart–Martinelli parameter based void fraction correlations have results close to each other at mass quality higher than 0.2. The drift flux void fraction correlations give small values which are incompatible with other models making it inapplicable for narrow rectangular channel. The alteration of void fraction correlations has an inconspicuous effect on two-phase frictional pressure drop, while an obvious effect on two-phase accelerational pressure drop during flow boiling in narrow rectangular channel

Jet-Surface Interaction: High Aspect Ratio Nozzle Test, Nozzle Design and Preliminary Data

Science.gov (United States)

Brown, Clifford; Dippold, Vance

2015-01-01

The Jet-Surface Interaction High Aspect Ratio (JSI-HAR) nozzle test is part of an ongoing effort to measure and predict the noise created when an aircraft engine exhausts close to an airframe surface. The JSI-HAR test is focused on parameters derived from the Turbo-electric Distributed Propulsion (TeDP) concept aircraft which include a high-aspect ratio mailslot exhaust nozzle, internal septa, and an aft deck. The size and mass flow rate limits of the test rig also limited the test nozzle to a 16:1 aspect ratio, half the approximately 32:1 on the TeDP concept. Also, unlike the aircraft, the test nozzle must transition from a single round duct on the High Flow Jet Exit Rig, located in the AeroAcoustic Propulsion Laboratory at the NASA Glenn Research Center, to the rectangular shape at the nozzle exit. A parametric nozzle design method was developed to design three low noise round-to-rectangular transitions, with 8:1, 12:1, and 16: aspect ratios, that minimizes flow separations and shocks while providing a flat flow profile at the nozzle exit. These designs validated using the WIND-US CFD code. A preliminary analysis of the test data shows that the actual flow profile is close to that predicted and that the noise results appear consistent with data from previous, smaller scale, tests. The JSI-HAR test is ongoing through October 2015. The results shown in the presentation are intended to provide an overview of the test and a first look at the preliminary results.

Analysis of counter current flow limitation during the cooling process at the rectangular narrow boundary

International Nuclear Information System (INIS)

Nur Rahmad Yusuf

2013-01-01

Experimental studies to study the mechanism of boiling heat transfer in narrow rectangular channel under severe accident scenarios of TMI-2 nuclear power plant necessary for the understanding of management-related accidents. The research aims to obtain heat flux values and the critical heat flux (CHF) during the process of boiling heat transfer in narrow rectangular channel. Research methods experimentally using the HEATING-02 test section with cooling fluid is water temperature 98 °C. Experiments performed by varying the hot plate initial temperature of 100 °C, 200 °C and 300 °C with channel size 1 mm. Boiling during the cooling process was recorded by a transient temperature on the hot plate. Temperature data used to calculate the heat flux and wall temperature, the results are represented through the boiling curve. The results show that the higher plate temperature, the narrower width of the curve will be narrower and its mean that the plate surface cooling time will be slower. Results visualization is seen that the CCF occurred at the hot plate initial temperature of 100 °C, 200 °C and 300 °C with channel size 1 mm. (author)

Detritiation studies for JET decommissioning

Energy Technology Data Exchange (ETDEWEB)

Perevezentsev, A.N.; Bell, A.C.; Williams, J.; Brennan, P.D. [EURATOM/UKAEA Fussion Association, Culham Science Centre, Abingdon (United Kingdom)

2007-07-01

JET is the world largest tokamak and has the capacity of operating with a tritium plasma. Three experimental campaigns, the Preliminary Tritium Experiment (0.1g T{sub 2}) in 1991, the Trace Tritium Experiment (5g T{sub 2}) in 2005, and the large experiment, the Deuterium-Tritium Experiment (DTE1) (100g T{sub 2}) in 1997, were carried out at JET with tritium plasmas. In DTE1 about 35 grams of tritium were fed directly into the vacuum vessel, with about 30% of this tritium being retained inside the vessel. In several years time JET will cease experimental operations and enter a decommissioning phase. In preparation for this the United Kingdom Atomic Energy Authority, the JET Operator, has been carrying out studies of various detritiation techniques. The materials which have been the subject of these studies include solid materials, such as various metals (Inconel 600 and 625, stainless steel 316L, beryllium, 'oxygen-free' copper, aluminium bronze), carbon fibre composite tiles, 'carbon' flakes and dust present in the vacuum vessel and also soft housekeeping materials. Liquid materials include organic liquids, such as vacuum oils and scintillation cocktails, and water. Detritiation of gas streams was also investigated. The purpose of the studies was to select and experimentally prove primary and auxiliary technologies for in-situ detritiation of in-vessel components and ex-situ detritiation of components removed from the vessel. The targets of ex-vessel detritiation were a reduction of the tritium inventory in and the rate of tritium out-gassing from the materials, and conversion, if possible, of intermediate level waste to low level waste and a reduction in volume of waste for disposal. The results of experimental trials and their potential application are presented. (orig.)

Helium-air counter flow in rectangular channels

International Nuclear Information System (INIS)

Fumizawa, Motoo; Tanaka, Gaku; Zhao, Hong; Hishida, Makoto; Shiina, Yasuaki

2004-01-01

This paper deals with numerical analysis of helium-air counter flow in a rectangular channel with an aspect ratio of 10. The channel has a cross sectional area of 5-50 mm and a length of 200 mm. The inclination angle was varied from 0 to 90 degree. The velocity profiles and concentration profiles were analyzed with a computer program [FLUENT]. Following main features of the counter flow are discussed based on the calculated results. (1) Time required for establishing a quasi-steady state counter flow. (2) The relationship between the inclination angle and the flow patterns of the counter flow. (3) The developing process of velocity profiles and concentration profiles. (4) The relationship between the inclination angle of the channel and the velocity profiles of upward flow and the downward flow. (5) The relationship between the concentration profile and the inclination angle. (6) The relationship between the net in-flow rate and the inclination angle. We compared the computed velocity profile and the net in-flow rate with experimental data. A good agreement was obtained between the calculation results and the experimental results. (author)

Study of powder formation in reactive coaxial jets

International Nuclear Information System (INIS)

Ablitzer, C.

1999-01-01

One step of the conversion of gaseous UF 6 to solid UO 2 by dry route is the formation of particles of UO 2 F 2 in a triple coaxial jet UF 6 /N 2 /H 2 O. The characteristics of resulting powder have an influence on the properties of final particles of UO 2 , and then on the quality of pellets of nuclear fuel. So a good control of this step of the process is of interest. This study deals with an experimental investigation and a modelling of the influence of various parameters on particles obtained by reaction in a turbulent coaxial jet. For example, the influence of absolute and relative velocities of gases on particle size distributions has been investigated. Two kinds of experimental studies have been undertaken. First, the development of mixing layers in the near field of the jet has been evaluated with temperature measurements. Then, particle size distributions have been measured with a turbidimetric sensor, for particles obtained by hydrolysis of gaseous metallic chlorides (SnCl 4 , TiCl 4 ) in double and triple coaxial jets. A model has been proposed for mixing of gases and growth of particles. It takes into account the development of mixing layers, meso-mixing, micro-mixing and growth of particles through agglomeration. The influence of operating parameters, especially velocities, on experimental results appear to be different for TiCl 4 /H 2 O jets and SnCl 4 /H 2 O jets. In fact, a comparison of theoretical and experimental results shows that particles obtained by hydrolysis of TiCl 4 seem to grow mainly through agglomeration whereas another growth phenomenon may be involved for particles obtained by hydrolysis of SnCl 4 . (author)

Errors generated with the use of rectangular collimation

International Nuclear Information System (INIS)

Parks, E.T.

1991-01-01

This study was designed to determine whether various techniques for achieving rectangular collimation generate different numbers and types of errors and remakes and to determine whether operator skill level influences errors and remakes. Eighteen students exposed full-mouth series of radiographs on manikins with the use of six techniques. The students were grouped according to skill level. The radiographs were evaluated for errors and remakes resulting from errors in the following categories: cone cutting, vertical angulation, and film placement. Significant differences were found among the techniques in cone cutting errors and remakes, vertical angulation errors and remakes, and total errors and remakes. Operator skill did not appear to influence the number or types of errors or remakes generated. Rectangular collimation techniques produced more errors than did the round collimation techniques. However, only one rectangular collimation technique generated significantly more remakes than the other techniques

Polydisperse particle-driven gravity currents in non-rectangular cross section channels

Science.gov (United States)

Zemach, T.

2018-01-01

We consider a high-Reynolds-number gravity current generated by polydisperse suspension of n types of particles distributed in a fluid of density ρi. Each class of particles in suspension has a different settling velocity. The current propagates along a channel of non-rectangular cross section into an ambient fluid of constant density ρa. The bottom and top of the channel are at z = 0, H, and the cross section is given by the quite general form -f1(z) ≤ y ≤ f2(z) for 0 ≤ z ≤ H. The flow is modeled by the one-layer shallow-water equations obtained for the time-dependent motion. We solve the problem by a finite-difference numerical code to present typical height h, velocity u, and mass fractions of particle (concentrations) (ϕ( j), j = 1, …, n) profiles. The runout length of suspensions in channels of power-law cross sections is analytically predicted using a simplified depth-averaged "box" model. We demonstrate that any degree of polydispersivity adds to the runout length of the currents, relative to that of equivalent monodisperse currents with an average settling velocity. The theoretical predictions are supported by the available experimental data. The present approach is a significant generalization of the particle-driven gravity current problem: on the one hand, now the monodisperse current in non-rectangular channels is a particular case of n = 1. On the other hand, the classical formulation of polydisperse currents for a rectangular channel is now just a particular case, f(z) = const., in the wide domain of cross sections covered by this new model.

Thermal interaction in crusted melt jets with large-scale structures

Energy Technology Data Exchange (ETDEWEB)

Sugiyama, Ken-ichiro; Sotome, Fuminori; Ishikawa, Michio [Hokkaido Univ., Sapporo (Japan). Faculty of Engineering

1998-01-01

The objective of the present study is to experimentally observe thermal interaction which would be capable of triggering due to entrainment, or entrapment in crusted melt jets with `large-scale structure`. The present experiment was carried out by dropping molten zinc and molten tin of 100 grams, of which mass was sufficient to generate large-scale structures of melt jets. The experimental results show that the thermal interaction of entrapment type occurs in molten-zinc jets with rare probability, and the thermal interaction of entrainment type occurs in molten tin jets with high probability. The difference of thermal interaction between molten zinc and molten tin may attribute to differences of kinematic viscosity and melting point between them. (author)

Experimental investigation of the liquid volumetric mass transfer coefficient for upward gas-liquid two-phase flow in rectangular microchannels

Directory of Open Access Journals (Sweden)

X. Y. Ji

2010-12-01

Full Text Available The gas-liquid two-phase mass transfer process in microchannels is complicated due to the special dynamical characteristics. In this work, a novel method was explored to measure the liquid side volumetric mass transfer coefficient kLa. Pressure transducers were utilized to measure the pressure variation of upward gas-liquid two-phase flow in three vertical rectangular microchannels and the liquid side volumetric mass transfer coefficient kLa was calculated through the Pressure-Volume-Temperature correlation of the gas phase. Carbon dioxide-water, carbon dioxide-ethanol and carbon dioxide-n-propanol were used as working fluids, respectively. The dimensions of the microchannels were 40 µm×240 µm (depth×width, 100 µm×800 µm and 100 µm×2000 µm, respectively. Results showed that the channel diameter and the capillary number influence kLa remarkably and that the maximum value of kLa occurs in the annular flow regime. A new correlation of kLa was proposed based on the Sherwood number, Schmidt number and the capillary number. The predicted values of kLa agreed well with the experimental data.

Influence of Fluid–Thermal–Structural Interaction on Boundary Layer Flow in Rectangular Supersonic Nozzles

Directory of Open Access Journals (Sweden)

Kalyani Bhide

2018-03-01

Full Text Available The aim of this work is to highlight the significance of Fluid–Thermal–Structural Interaction (FTSI as a diagnosis of existing designs, and as a means of preliminary investigation to ensure the feasibility of new designs before conducting experimental and field tests. The novelty of this work lies in the multi-physics simulations, which are, for the first time, performed on rectangular nozzles. An existing experimental supersonic rectangular converging/diverging nozzle geometry is considered for multi-physics 3D simulations. A design that has been improved by eliminating the sharp throat is further investigated to evaluate its structural integrity at design Nozzle Pressure Ratio (NPR 3.67 and off-design (NPR 4.5 conditions. Static structural analysis is performed by unidirectional coupling of pressure loads from steady 3D Computational Fluid Dynamics (CFD and thermal loads from steady thermal conduction simulations, such that the simulations represent the experimental set up. Structural deformation in the existing design is far less than the boundary layer thickness, because the impact of Shock wave Boundary Layer Interaction (SBLI is not as severe. FTSI demonstrates that the discharge coefficient of the improved design is 0.99, and its structural integrity remains intact at off-design conditions. This proves the feasibility of the improved design. Although FTSI influence is shown for a nozzle, the approach can be applied to any product design cycle, or as a prelude to building prototypes.

Jet pumps hydrdynamics for application on BWRS

International Nuclear Information System (INIS)

Girardi, G.; Pitimada, D.

1979-01-01

An analysis of single-phase jet-pump hydrodynamics is carried out by this paper with special regard to the applications on cooling water recirculation in the boiling water reactors (BWR). Firstly, in order to asses on efficiency of jet pumps, several theories regarding the hydrodynamic of these machines are also investigated. The results of the above theories are critically analysed and compared regarding to water-jet-pump design, to operational performance curves and to section limits. Some general criteria in jet-pump design are introduced and values of geometric and kinematic parameters are suggested together with losses coefficients which are all concerned with the ''high ratio'' type jet pump of this typical application. Finally, the experimental test program following the sim of this research is briefly described

Buoyancy effects in vertical rectangular duct with coplanar magnetic field and single sided heat load

Science.gov (United States)

Kostichev, P. I.; Poddubnyi, I. I.; Razuvanov, N. G.

2017-11-01

In some DEMO blanket designs liquid metal flows in vertical ducts of rectangular cross-section between ceramic breeder units providing their cooling. Heat exchange in these conditions is governed by the influence of magnetic field (coplanar) and by buoyancy effects that depend on the flow orientation to the gravity vector (downward and upward flow). Magnetohydrodynamic and heat transfer of liquid metal in vertical rectangular ducts is not well researched. Experimental study of buoyancy effects in rectangular duct with coplanar magnetic field for one-sided heat load and downward and upward flowsis presented in this paper. The detail research with has been done on mercury MHD close loop with using of the probe technique allow to discover several advantageous and disadvantageous effects. The intensive impact of buoyancy force has been observed in a few regime of downward flow which has been laminarized by magnetic field. Due to the development in the flow of the secondary large-scale vortices heat transfer improved and the temperature fluctuations of the abnormally high intensity have been fixed. On the contrary, in the upward flow the buoyancy force stabilized the flow which lead to decreasing of the turbulence heat transfer ratio and, consequently, deterioration of heat transfer.

Microwave corrosion detection using open ended rectangular waveguide sensors

Energy Technology Data Exchange (ETDEWEB)

Qaddoumi, N.; Handjojo, L.; Bigelow, T.; Easter, J.; Bray, A.; Zoughi, R.

2000-02-01

The use of microwave and millimeter wave nondestructive testing methods utilizing open ended rectangular waveguide sensors has shown great potential for detecting minute thickness variations in laminate structures, in particular those backed by a conducting plate. Slight variations in the dielectric properties of materials may also be detected using a set of optimal parameters which include the standoff distance and the frequency of operation. In a recent investigation, on detecting rust under paint, the dielectric properties of rust were assumed to be similar to those of Fe{sub 2}O{sub 3} powder. These values were used in an electromagnetic model that simulates the interaction of fields radiated by a rectangular waveguide aperture with layered structures to obtain optimal parameters. The dielectric properties of Fe{sub 2}O{sub 3} were measured to be very similar to the properties of paint. Nevertheless, the presence of a simulated Fe{sub 2}O{sub 3} layer under a paint layer was detected. In this paper the dielectric properties of several different rust samples from different environments are measured. The measurements indicate that the nature of real rust is quite diverse and is different from Fe{sub 2}O{sub 3} and paint, indicating that the presence of rust under paint can be easily detected. The same electromagnetic model is also used (with the newly measured dielectric properties of real rust) to obtain an optimal standoff distance at a frequency of 24 GHz. The results indicate that variations in the magnitude as well as the phase of the reflection coefficient can be used to obtain information about the presence of rust. An experimental investigation on detecting the presence of very thin rust layers (2.5--5 x 10{sup {minus}2} mm [09--2.0 x 10{sup {minus}3} in.]) using an open ended rectangular waveguide probe is also conducted. Microwave images of rusted specimens, obtained at 24 GHz, are also presented.

Mixing by turbulent buoyant jets in slender containers

International Nuclear Information System (INIS)

Voropayev, S.I.; Nath, C.; Fernando, H.J.S.

2012-01-01

A turbulent buoyant jet injected vertically into a slender cylinder containing a stratified fluid is investigated experimentally. The working fluid is water, and salt is used to change its density to obtain either a positively or negatively buoyant jet. The interest is the vertical density distribution in container and its dependence on time and other parameters. For each case (lighter or heavier jet) the experimental data could be collapsed into a ‘universal’ time dependent behavior, when properly non-dimensionalized. A theoretical model is advanced to explain the results. Possible applications include refilling of crude oil into U.S. strategic petroleum reserves caverns. -- Highlights: ► We addresses a critical issue on refill of Strategic Petroleum Reserves. ► We conduct experiments on negatively/positively buoyant turbulent jets in long cavern. ► Basing on results of experiments we developed theoretical model for refill operations.

Rectangular optical filter based on high-order silicon microring resonators

Science.gov (United States)

Bao, Jia-qi; Yu, Kan; Wang, Li-jun; Yin, Juan-juan

2017-07-01

The rectangular optical filter is one of the most important optical switching components in the dense wavelength division multiplexing (DWDM) fiber-optic communication system and the intelligent optical network. The integrated highorder silicon microring resonator (MRR) is one of the best candidates to achieve rectangular filtering spectrum response. In general, the spectrum response rectangular degree of the single MRR is very low, so it cannot be used in the DWDM system. Using the high-order MRRs, the bandwidth of flat-top pass band, the out-of-band rejection degree and the roll-off coefficient of the edge will be improved obviously. In this paper, a rectangular optical filter based on highorder MRRs with uniform couplers is presented and demonstrated. Using 15 coupled race-track MRRs with 10 μm in radius, the 3 dB flat-top pass band of 2 nm, the out-of-band rejection ratio of 30 dB and the rising and falling edges of 48 dB/nm can be realized successfully.

Rectangular optical filter based on high-order silicon microring resonators

Institute of Scientific and Technical Information of China (English)

BAO Jia-qi; YU Kan; WANG Li-jun; YIN Juan-juan

2017-01-01

The rectangular optical filter is one of the most important optical switching components in the dense wavelength division multiplexing (DWDM) fiber-optic communication system and the intelligent optical network.The integrated highorder silicon microring resonator (MRR) is one of the best candidates to achieve rectangular filtering spectrum response.In general,the spectrum response rectangular degree of the single MRR is very low,so it cannot be used in the DWDM system.Using the high-order MRRs,the bandwidth of flat-top pass band,the out-of-band rejection degree and the roll-off coefficient of the edge will be improved obviously.In this paper,a rectangular optical filter based on highorder MRRs with uniform couplers is presented and demonstrated.Using 15 coupled race-track MRRs with 10 μm in radius,the 3 dB flat-top pass band of 2 nm,the out-of-band rejection ratio of 30 dB and the rising and falling edges of 48 dB/nm can be realized successfully.

Comparison of rectangular and dual-planar positron emission mammography scanners

International Nuclear Information System (INIS)

Qi, Jinyi; Kuo, Chaincy; Huesman, Ronald H.; Klein, Gregory J.; Moses, William W.; Reutter, Bryan W.

2002-01-01

Breast imaging using dedicated positron emission tomography (PEM) has gained much interest in the medical imaging field. In this paper, we compare the performance between a rectangular geometry and a parallel dual-planar geometry. Both geometries are studied with depth of interaction (DOI) detectors and non- DOI detectors. We compare the Fisher-information matrix, lesion detection, and quantitation of the four systems. The lesion detectability is measured by the signal-to-noise ratio (SNR) of a prewhitening numerical observer for detecting a known hot spot on a uniform background. Results show that the rectangular system with DOI has the highest SNR for the detection task and the lowest bias at any given noise level for the quantitation task. They also show that for small simulated lesions the parallel dual-planar system with DOI detectors outperforms the rectangular system with non-DOI detectors, while the rectangular system with non-DOI detectors can outperform the parallel dual-planar system with DOI detectors for large simulated lesions

A CPW-Fed Rectangular Ring Monopole Antenna for WLAN Applications

Directory of Open Access Journals (Sweden)

Sangjin Jo

2014-01-01

Full Text Available We present a simple coplanar waveguide- (CPW- fed rectangular ring monopole antenna designed for dual-band wireless local area network (WLAN applications. The antenna is based on a simple structure composed of a CPW feed line and a rectangular ring. Dual-band WLAN operation can be achieved by controlling the distance between the rectangular ring and the ground plane of the CPW feed line, as well as the horizontal vertical lengths of the rectangular ring. Simulated and measured data show that the antenna has a compact size of 21.4×59.4 mm2, an impedance bandwidths of 2.21–2.70 GHz and 5.04–6.03 GHz, and a reflection coefficient of less than −10 dB. The antenna also exhibits an almost omnidirectional radiation pattern. This simple compact antenna with favorable frequency characteristics therefore is attractive for applications in dual-band WLAN.

Thermal vibration of a rectangular single-layered graphene sheet with quantum effects

International Nuclear Information System (INIS)

Wang, Lifeng; Hu, Haiyan

2014-01-01

The thermal vibration of a rectangular single-layered graphene sheet is investigated by using a rectangular nonlocal elastic plate model with quantum effects taken into account when the law of energy equipartition is unreliable. The relation between the temperature and the Root of Mean Squared (RMS) amplitude of vibration at any point of the rectangular single-layered graphene sheet in simply supported case is derived first from the rectangular nonlocal elastic plate model with the strain gradient of the second order taken into consideration so as to characterize the effect of microstructure of the graphene sheet. Then, the RMS amplitude of thermal vibration of a rectangular single-layered graphene sheet simply supported on an elastic foundation is derived. The study shows that the RMS amplitude of the rectangular single-layered graphene sheet predicted from the quantum theory is lower than that predicted from the law of energy equipartition. The maximal relative difference of RMS amplitude of thermal vibration appears at the sheet corners. The microstructure of the graphene sheet has a little effect on the thermal vibrations of lower modes, but exhibits an obvious effect on the thermal vibrations of higher modes. The quantum effect is more important for the thermal vibration of higher modes in the case of smaller sides and lower temperature. The relative difference of maximal RMS amplitude of thermal vibration of a rectangular single-layered graphene sheet decreases monotonically with an increase of temperature. The absolute difference of maximal RMS amplitude of thermal vibration of a rectangular single-layered graphene sheet increases slowly with the rising of Winkler foundation modulus.

Research on the comparison of extension mechanism of cellular automaton based on hexagon grid and rectangular grid

Science.gov (United States)

Zhai, Xiaofang; Zhu, Xinyan; Xiao, Zhifeng; Weng, Jie

2009-10-01

Historically, cellular automata (CA) is a discrete dynamical mathematical structure defined on spatial grid. Research on cellular automata system (CAS) has focused on rule sets and initial condition and has not discussed its adjacency. Thus, the main focus of our study is the effect of adjacency on CA behavior. This paper is to compare rectangular grids with hexagonal grids on their characteristics, strengths and weaknesses. They have great influence on modeling effects and other applications including the role of nearest neighborhood in experimental design. Our researches present that rectangular and hexagonal grids have different characteristics. They are adapted to distinct aspects, and the regular rectangular or square grid is used more often than the hexagonal grid. But their relative merits have not been widely discussed. The rectangular grid is generally preferred because of its symmetry, especially in orthogonal co-ordinate system and the frequent use of raster from Geographic Information System (GIS). However, in terms of complex terrain, uncertain and multidirectional region, we have preferred hexagonal grids and methods to facilitate and simplify the problem. Hexagonal grids can overcome directional warp and have some unique characteristics. For example, hexagonal grids have a simpler and more symmetric nearest neighborhood, which avoids the ambiguities of the rectangular grids. Movement paths or connectivity, the most compact arrangement of pixels, make hexagonal appear great dominance in the process of modeling and analysis. The selection of an appropriate grid should be based on the requirements and objectives of the application. We use rectangular and hexagonal grids respectively for developing city model. At the same time we make use of remote sensing images and acquire 2002 and 2005 land state of Wuhan. On the base of city land state in 2002, we make use of CA to simulate reasonable form of city in 2005. Hereby, these results provide a proof of

Exploratory investigation of the HIPPO gas-jet target fluid dynamic properties

Energy Technology Data Exchange (ETDEWEB)

Meisel, Zach, E-mail: zmeisel@nd.edu [Department of Physics, Joint Institute for Nuclear Astrophysics, University of Notre Dame, Notre Dame, IN 46556 (United States); Shi, Ke; Jemcov, Aleksandar [Hessert Laboratory for Aerospace Research, Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556 (United States); Couder, Manoel [Department of Physics, Joint Institute for Nuclear Astrophysics, University of Notre Dame, Notre Dame, IN 46556 (United States)

2016-08-21

In order to optimize the performance of gas-jet targets for future nuclear reaction measurements, a detailed understanding of the dependence of the gas-jet properties on experiment design parameters is required. Common methods of gas-jet characterization rely on measuring the effective thickness using nuclear elastic scattering and energy loss techniques; however, these tests are time intensive and limit the range of design modifications which can be explored to improve the properties of the jet as a nuclear reaction target. Thus, a more rapid jet-characterization method is desired. We performed the first steps towards characterizing the gas-jet density distribution of the HIPPO gas-jet target at the University of Notre Dame's Nuclear Science Laboratory by reproducing results from {sup 20}Ne(α,α){sup 20}Ne elastic scattering measurements with computational fluid dynamics (CFD) simulations performed with the state-of-the-art CFD software ANSYS Fluent. We find a strong sensitivity to experimental design parameters of the gas-jet target, such as the jet nozzle geometry and ambient pressure of the target chamber. We argue that improved predictive power will require moving to three-dimensional simulations and additional benchmarking with experimental data.

Spectral Optical Readout of Rectangular-Miniature Hollow Glass Tubing for Refractive Index Sensing.

Science.gov (United States)

Rigamonti, Giulia; Bello, Valentina; Merlo, Sabina

2018-02-16

For answering the growing demand of innovative micro-fluidic devices able to measure the refractive index of samples in extremely low volumes, this paper presents an overview of the performances of a micro-opto-fluidic sensing platform that employs rectangular, miniature hollow glass tubings. The operating principle is described by showing the analytical model of the tubing, obtained as superposition of different optical cavities, and the optical readout method based on spectral reflectivity detection. We have analyzed, in particular, the theoretical and experimental optical features of rectangular tubings with asymmetrical geometry, thus with channel depth larger than the thickness of the glass walls, though all of them in the range of a few tens of micrometers. The origins of the complex line-shape of the spectral response in reflection, due to the different cavities formed by the tubing flat walls and channel, have been investigated using a Fourier transform analysis. The implemented instrumental configuration, based on standard telecom fiberoptic components and a semiconductor broadband optical source emitting in the near infrared wavelength region centered at 1.55 µm, has allowed acquisition of reflectivity spectra for experimental verification of the expected theoretical behavior. We have achieved detection of refractive index variations related to the change of concentration of glucose-water solutions flowing through the tubing by monitoring the spectral shift of the optical resonances.

Experimental and Numerical Investigation of Forced Convection Heat Transfer in Heat Sink with Rectangular Plates at Varying Inclinations on Vertical Base

Science.gov (United States)

Patil, Harshal Bhauso; Dingare, Sunil Vishnu

2018-03-01

Heat exchange upgrade is a vital territory of research area. Utilization of reasonable systems can bring about noteworthy specialized points of interest coming about reserve funds of cost. Rectangular plates are viewed as best balance arrangement utilized for heat exchange improvement. This gives an enlargement strategy to heat exchange with beginning of limit layer and vortex development. To assess and look at the rate of heat exchange enhancement by rectangular plate fins with differing inclinations (0°-30°-60°), shifting Re and heat supply under forced convection are the principle destinations of this study. The study is done by fluctuating introductions of fins with various inclinations, input heat supply and Re under forced convection. The coefficient of heat transfer increments observed with the expansion in air speed for all the examined designs. The coefficient of the heat transfer is discovered higher at the edge of introduction of fins at 30° for inline arrangement and 0° for staggered arrangement. Looking at both the arrangements, it is discovered that the heat transfer coefficient in 0° fin staggered arrangement is about 17% higher than 30° inline arrangement and 76% higher than the vertical plate fin. For plate fin heat sink, boundary layer formation and growth results in decrease of the coefficient of heat transfer in forced convection. This issue is overcome by accommodating some rectangular fins on the plate fin. It brings about increment of heat transfer coefficient of the RPFHS under the states of trial factors. As indicated by past research, it is discovered that examination of the plate fin heat sink with various sorts of fins for horizontal orientation is done yet but this investigation expects to discover the upgrade of transfer coefficient of plate fin heat sink for its vertical position with rectangular plates at different inclinations under the shifting scopes of heat input supply, fin arrangements and Reynolds number (Re).

Enhanced Circular Dichroism of Gold Bilayered Slit Arrays Embedded with Rectangular Holes.

Science.gov (United States)

Zhang, Hao; Wang, Yongkai; Luo, Lina; Wang, Haiqing; Zhang, Zhongyue

2017-01-01

Gold bilayered slit arrays with rectangular holes embedded into the metal surface are designed to enhance the circular dichroism (CD) effect of gold bilayered slit arrays. The rectangular holes in these arrays block electric currents and generate localized surface plasmons around these holes, thereby strengthening the CD effect. The CD enhancement factor depends strongly on the rotational angle and the structural parameters of the rectangular holes; this factor can be enhanced further by drilling two additional rectangular holes into the metal surfaces of the arrays. These results help facilitate the design of chiral structures to produce a strong CD effect and large electric fields.

Seismic Performance of RC Beam-Column Connections with Continuous Rectangular Spiral Transverse Reinforcements for Low Ductility Classes

Directory of Open Access Journals (Sweden)

Mohammadamin Azimi

2014-01-01

Full Text Available The seismic performance of RC columns could be significantly improved by continuous spiral reinforcement as a result of its adequate ductility and energy dissipation capacity. Due to post-earthquake brittle failure observations in beam-column connections, the seismic behaviour of such connections could greatly be improved by simultaneous application of this method in both beams and columns. In this study, a new proposed detail for beam to column connection introduced as “twisted opposing rectangular spiral” was experimentally and numerically investigated and its seismic performance was compared against normal rectangular spiral and conventional shear reinforcement systems. In this study, three full scale beam to column connections were first designed in conformance with Eurocode (EC2-04 for low ductility class connections and then tested by quasistatic cyclic loading recommended by ACI Building Code (ACI 318-02. Next, the experimental results were validated by numerical methods. Finally, the results revealed that the new proposed connection could improve the ultimate lateral resistance, ductility, and energy dissipation capacity.

Experimental investigation of turbulence modulation in particle-laden coaxial jets by Phase Doppler Anemometry

Energy Technology Data Exchange (ETDEWEB)

Mergheni, M.A. [CORIA UMR 6614 CNRS, Universite et INSA de ROUEN, Avenue de l' Universite, BP 12, 76801 Saint Etienne du Rouvray, Cedex (France)]|[LESTE Ecole Nationale d' Ingenieurs de Monastir, 5019 Monastir (Tunisia); Sautet, J.C.; Godard, G. [CORIA UMR 6614 CNRS, Universite et INSA de ROUEN, Avenue de l' Universite, BP 12, 76801 Saint Etienne du Rouvray, Cedex (France); Ben Ticha, H.; Ben Nasrallah, S. [LESTE Ecole Nationale d' Ingenieurs de Monastir, 5019 Monastir (Tunisia)

2009-03-15

The effect of solid particles on the flow characteristics of axisymmetric turbulent coaxial jets for two flow conditions was studied. Simultaneous measurements of size and velocity distributions of continuous and dispersed phases in a two-phase flow are presented using a Phase Doppler Anemometry (PDA) technique. Spherical glass particles with a particle diameter range from 102 to 212 {mu}m were used in this two-phase flow, the experimental results indicate a significant influence of the solid particles and the Re on the flow characteristics. The data show that the gas phase has lower mean velocity in the near-injector region and a higher mean velocity at the developed region. Near the injector at low Reynolds number (Re = 2839) the presence of the particles dampens the gas-phase turbulence, while at higher Reynolds number (Re = 11 893) the gas-phase turbulence and the velocity fluctuation of particle-laden jets are increased. The particle velocity at higher Reynolds number (Re = 11 893) and is lower at lower Reynolds number (Re = 2839). The slip velocity between particles and gas phase existed over the flow domain was examined. More importantly, the present experiment results suggest that, consideration of the gas characteristic length scales is insufficient to predict gas-phase turbulence modulation in gas-particle flows. (author)

Experimental investigation of a pilot-scale jet bubbling reactor for wet flue gas desulphurisation

DEFF Research Database (Denmark)

Zheng, Yuanjing; Kiil, Søren; Johnsson, Jan Erik

2003-01-01

In the present work, an experimental parameter study was conducted in a pilot-scale jet bubbling reactor for wet flue gas desulphurisation (FGD). The pilot plant is downscaled from a limestone-based, gypsum producing full-scale wet FGD plant. Important process parameters, such as slurry pH, inlet...... flue gas concentration of SO2, reactor temperature, and slurry concentration of Cl- have been varied. The degree of desulphurisation, residual limestone content of the gypsum, liquid phase concentrations, and solids content of the slurry were measured during the experimental series. The SO2 removal...... efficiency increased from 66.1% to 71.5% when the reactor slurry pH was changed from 3.5 to 5.5. Addition of Cl(in the form of CaCl2 . 2H(2)O) to the slurry (25 g Cl-/l) increased the degree of desulphurisation to above 99%, due to the onset of extensive foaming, which substantially increased the gas...

Implications of Upwells as Hydrodynamic Jets in a Pulse Jet Mixed System

Energy Technology Data Exchange (ETDEWEB)

Pease, Leonard F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bamberger, Judith A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Minette, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2015-08-01

satisfies these criteria when vigorous breakthrough is achieved, not all available data follow the free jet profile for the central upwell, particularly at lower nozzle velocities. Alternative flow regimes are considered and new models for cloud height, “cavern height,” and the rate of jet penetration (jet celerity) are benchmarked against data to anchor scaling analyses. This analytical modeling effort to provide a technical basis for scaling PJM mixed vessels has significant implications for vessel mixing, because jet physics underlies “cavern” height, cloud height, and the volume of mixing considerations. A new four-parameter cloud height model compares favorably to experimental results. This model is predictive of breakthrough in 8 ft vessel tests with the two-part simulant. Analysis of the upwell in the presence of yield stresses finds evidence of expanding turbulent jets, confined turbulent jets, and confined laminar flows. For each, the critical elevation at which jet momentum depletes is predicted, which compare favorably to experimental cavern height data. Partially coupled momentum and energy balances suggest that these are limiting cases of a gradual transition from a turbulent expanding flow to a confined laminar flow. This analysis of the central upwell alone lays essential groundwork for complete analysis of mode three mixing (i.e., breakthrough with slow peripheral mixing). Consideration of jet celerity shows that the rate of jet penetration is a governing consideration in breakthrough to the surface. Estimates of the volume of mixing are presented. This analysis shows that flow along the vessel wall is sluggish such that the central upwell governs the volume of mixing. This analysis of the central upwell alone lays essential groundwork for complete analysis of mode three mixing and estimates of hydrogen release rates from first principles.

Experimental studies of rectangular tube absorber photovoltaic thermal collector with various types of nanofluids under the tropical climate conditions

International Nuclear Information System (INIS)

Al-Shamani, Ali Najah; Sopian, K.; Mat, Sohif; Hasan, Husam Abdulrasool; Abed, Azher M.; Ruslan, M.H.

2016-01-01

Highlights: • A new rectangular tube as absorber for the PVT solar collector was developed. • Different types of nanofluids (SiO_2, TiO_2 and SiC) evaluated. • η_e_l PVT SiC nanofluid was 13.52% at 1000 W/m"2 and flow rate of 0.17 kg/s. • η_c_o_m_b_i_n_e_d PVT SiC nanofluid was 81.73% at 1000 W/m"2 and flow rate of 0.17 kg/s. - Abstract: The flat plate photovoltaic thermal (PVT) collectors can be classified into the type of working fluids used namely the water based PVT collectors, air based PVT collectors and combination of water/air PVT collectors. However, low thermal conductivity of the working fluids has always been the primary limitation in the development of energy-efficient heat transfer fluids, and higher collector performance. To overcome this limitation, there is a strong motivation to improve the heat transfer of fluids with higher thermal conductivity. This new generation of heat transfer fluids called nanofluids consists of suspended nanoparticles and has higher suspension stability compared to the millimeter or micrometer size nanoparticles. Thus, the heat transfer characteristics will be enhanced by using nanofluids. The PVT collector has been designed, fabricated and tested outdoor under the Malaysia tropical climate conditions. The PVT collector consists of specially designed rectangular tube absorber (stainless steel material, height of 15 mm, width of 25 mm and thickness of 1 mm) attached under the photovoltaic module. The PVT collector was experimentally tested with different types of nanofluids (SiO_2, TiO_2 and SiC). The results indicated that the PVT collector with SiC nanofluid has the highest combined photovoltaic thermal (PVT) efficiency of 81.73% and PVT electrical efficiency of 13.52% with the best overall energy coefficient (COE) of 0.93 has been achieved at a flow rate of 0.170 kg/s and solar irradiance levels of 1000 W/m"2, followed by PVT-TiO_2 nanofluids, PVT-SiO_2 nanofluids, and PVT-water respectively.

Experimental study of a separated jets burner: application to the natural gas-pure oxygen combustion; Etude experimentale du comportement de bruleurs a jets separes: application a la combustion gaz naturel-oxygene pur

Energy Technology Data Exchange (ETDEWEB)

Salentey, L.

2002-04-15

The evolution of pollution standards and the optimisation of furnaces performances require a development of new burner generation and also the improvement of combustion techniques. Actually, the use of oxy-combustion in separated jets burners offers interesting prospects for NO{sub x} emission reduction and on the modularity of flames properties (lift off, flame front topology, flame length). The complex geometry of those burners leads to several problems like the three-dimensional character of the flow, which may sometimes disturb the flame stability as flames are lifted above the burner. This experimental study deals with a simplified version of that kind of burner constituted with a central natural gas jet surrounded by two oxygen jets. Primary, the study of non-reactive jet was planned in order to understand dynamic and mixture phenomena involved between jets and to provide a database useful for the computer code validation. The reactive flow developed in a furnace, which simulates the real conditions, had been characterised. The studies of the dynamic field using Laser Doppler Velocimetry (LDV) and of the turbulent mixture by conditional Laser tomography were supplemented in combustion by the visualisation of the spontaneous emission of radical OH, in the initial and final zone of the oxy-flames, like by the measurement of pollutants like NO{sub x} and soot. The measurements carried out while varying speeds of injection as well as the gap between the jets made possible the highlight of the influence of these parameters upon the stabilisation of the oxy-flames as well as the modification of the topology and the characteristics of the flows. The comparison of the measurements made in non-reactive and reactive flow shows the influence of oxy-combustion on the dynamic and scalar development of the flow for this type of burners. (author)

Experimental evaluation of ammonia adiabatic absorption into ammonia–lithium nitrate solution using a fog jet nozzle

International Nuclear Information System (INIS)

Zacarías, Alejandro; Venegas, María; Lecuona, Antonio; Ventas, Rubén

2013-01-01

This paper presents the experimental assessment of the adiabatic absorption of ammonia vapour into an ammonia–lithium nitrate solution using a fog jet nozzle. The ammonia mass fraction was kept constant at 46.08% and the absorber pressure was varied in the range 355–411 kPa. The nozzle was located at the top of the absorption chamber, at a height of 205 mm measured from the bottom surface. The diluted solution flow rate was modified between 0.04 and 0.08 kg s −1 and the solution inlet temperature in the range 25.9–30.2 °C. The influence of these variables on the approach to adiabatic equilibrium factor, outlet subcooling, absorption ratio and mass transfer coefficient is analysed. The approach to adiabatic equilibrium factor for the conditions essayed is always between 0.82 and 0.93. Pressure drop of the solution entering the absorption chamber is also evaluated. Correlations for the approach to adiabatic equilibrium factor and the Sherwood number are given. - Highlights: ► Adiabatic absorption of NH 3 vapour into NH 3 –LiNO 3 using fog jet nozzle created spray. ► Pressure drop of the solution entering to the absorption chamber is evaluated. ► Approach to adiabatic equilibrium factor (F) is between 0.82 and 0.93 at 205 mm height. ► Experimental values of mass transfer coefficient and outlet subcooling are presented. ► Correlations for F and Sherwood number are given.

Jets as a probe of dense matter at RHIC

International Nuclear Information System (INIS)

Filimonov, Kirill

2004-01-01

Jet quenching in the matter created in high energy nucleus-nucleus collisions provides a tomographic tool to probe the medium properties. Recent experimental results on jet production at the Relativistic Heavy-Ion Collider (RHIC) are reviewed. Jet properties in p+p and d+Au collisions have been measured, establishing the baseline for studying jet modification in heavy-ion collisions. Current progress on detailed studies of high transverse momentum production in Au+Au collisions is discussed, with an emphasis on dihadron correlation measurements

QCD analysis of jets in e/sup +/e/sup -/ annihilation

Energy Technology Data Exchange (ETDEWEB)

Ali, A

1980-10-01

Jets in e/sup +/e/sup -/ annihilation are discussed in the context of perturbative Quantum Chromodynamics. Topics discussed include higher twist contribution, effects of quark masses and fragmentation on the 3 and 4 jet rates and some distributions bearing on the experimental verification of 4 jet events at the PETRA/PEP energies.

On Mathematical Optimization for the Visualization of Frequencies and Adjacencies as Rectangular Maps

DEFF Research Database (Denmark)

Carrizosa, Emilio; Guerrero, Vanesa; Morales, Dolores Romero

2018-01-01

individuals as adjacent rectangular portions as possible and adding as few false adjacencies, i.e., adjacencies between rectangular portions corresponding to non-adjacent individuals, as possible. We formulate this visualization problem as a Mixed Integer Linear Programming (MILP) model. We propose......In this paper we address the problem of visualizing a frequency distribution and an adjacency relation attached to a set of individuals. We represent this information using a rectangular map, i.e., a subdivision of a rectangle into rectangular portions so that each portion is associated with one...

Analysis of junior high school students' difficulty in resolving rectangular conceptual problems

Science.gov (United States)

Utami, Aliksia Kristiana Dwi; Mardiyana, Pramudya, Ikrar

2017-08-01

Geometry is one part of the mathematics that must be learned in school and it has important effects on the development of creative thinking skills of learners, but in fact, there are some difficulties experienced by the students. This research focuses on analysis difficulty in resolving rectangular conceptual problems among junior high school students in every creative thinking skills level. This research used a descriptive method aimed to identify the difficulties and cause of the difficulties experienced by five students. The difficulties are associated with rectangular shapes and related problems. Data collection was done based on students' work through test, interview, and observations. The result revealed that student' difficulties in understanding the rectangular concept can be found at every creative thinking skills level. The difficulties are identifying the objects rectangular in the daily life except for a rectangle and square, analyzing the properties of rectangular shapes, and seeing the interrelationships between figures.

A note on high Schmidt number laminar buoyant jets discharged horizontally

International Nuclear Information System (INIS)

Dewan, A.; Arakeri, J.H.; Srinivasan, J.

1992-01-01

This paper reports on a new model, developed for the integral analysis of high Schmidt number (or equivalently high Prandtl number) laminar buoyant jets discharged horizontally. This model assumes top-hat density profile across the inner core of jet and Gaussian velocity profile. Entrainment coefficient corresponding to pure laminar jet has been taken in the analysis. The prediction of the jet trajectory agree well with experimental data in the regions where the jet remains laminar

Neutron streaming studies along JET shielding penetrations

Science.gov (United States)

Stamatelatos, Ion E.; Vasilopoulou, Theodora; Batistoni, Paola; Obryk, Barbara; Popovichev, Sergey; Naish, Jonathan

2017-09-01

Neutronic benchmark experiments are carried out at JET aiming to assess the neutronic codes and data used in ITER analysis. Among other activities, experiments are performed in order to validate neutron streaming simulations along long penetrations in the JET shielding configuration. In this work, neutron streaming calculations along the JET personnel entrance maze are presented. Simulations were performed using the MCNP code for Deuterium-Deuterium and Deuterium- Tritium plasma sources. The results of the simulations were compared against experimental data obtained using thermoluminescence detectors and activation foils.

Inertial manipulation of bubbles in rectangular microfluidic channels.

Science.gov (United States)

Hadikhani, Pooria; Hashemi, S Mohammad H; Balestra, Gioele; Zhu, Lailai; Modestino, Miguel A; Gallaire, François; Psaltis, Demetri

2018-03-27

Inertial microfluidics is an active field of research that deals with crossflow positioning of the suspended entities in microflows. Until now, the majority of the studies have focused on the behavior of rigid particles in order to provide guidelines for microfluidic applications such as sorting and filtering. Deformable entities such as bubbles and droplets are considered in fewer studies despite their importance in multiphase microflows. In this paper, we show that the trajectory of bubbles flowing in rectangular and square microchannels can be controlled by tuning the balance of forces acting on them. A T-junction geometry is employed to introduce bubbles into a microchannel and analyze their lateral equilibrium position in a range of Reynolds (1 < Re < 40) and capillary numbers (0.1 < Ca < 1). We find that the Reynolds number (Re), the capillary number (Ca), the diameter of the bubble (D[combining macron]), and the aspect ratio of the channel are the influential parameters in this phenomenon. For instance, at high Re, the flow pushes the bubble towards the wall while large Ca or D[combining macron] moves the bubble towards the center. Moreover, in the shallow channels, having aspect ratios higher than one, the bubble moves towards the narrower sidewalls. One important outcome of this study is that the equilibrium position of bubbles in rectangular channels is different from that of solid particles. The experimental observations are in good agreement with the performed numerical simulations and provide insights into the dynamics of bubbles in laminar flows which can be utilized in the design of flow based multiphase flow reactors.

Bouncing and Merging of Liquid Jets

Science.gov (United States)

Saha, Abhishek; Li, Minglei; Law, Chung K.

2014-11-01

Collision of two fluid jets is a technique that is utilized in many industrial applications, such as in rocket engines, to achieve controlled mixing, atomization and sometimes liquid phase reactions. Thus, the dynamics of colliding jets have direct impact on the performance, efficiency and reliability of such applications. In analogy with the dynamics of droplet-droplet collision, in this work we have experimentally demonstrated, for n-alkane hydrocarbons as well as water, that with increasing impact inertia obliquely colliding jets also exhibit the same nonmonotonic responses of merging, bouncing, merging again, and merging followed by disintegration; and that the continuous entrainment of the boundary layer air over the jet surface into the colliding interfacial region leads to two distinguishing features of jet collision, namely: there exists a maximum impact angle beyond which merging is always possible, and that merging is inhibited and then promoted with increasing pressure. These distinct response regimes were mapped and explained on the bases of impact inertia, deformation of the jet surface, viscous loss within the jet interior, and the thickness and pressure build-up within the interfacial region in order to activate the attractive surface van der Waals force to effect merging.

Experimental study of critical heat flux in inclined rectangular gap

International Nuclear Information System (INIS)

Kim, S.J.; Kim, Y.H.; Noh, S.W.; Suh, K.Y.; Rempe, J.L.; Cheung, F.B.; Kim, S.B.

2003-01-01

In the TMI-2 accident, the lower part of the reactor pressure vessel was overheated and then rather rapidly cooled down, as was later found out in a vessel investigation project. This accounted for the possibility of gap cooling feasibility. For this reason, a great deal of investigations was performed to determine the critical heat flux (CHF) from the standpoint of in-vessel retention (IVR). As part of a joint Korean-U.S. International Nuclear Energy Research Initiative (INERI) project, Tests were conducted to examine the critical heat flux (CHF) on the one-dimensional downward heating rectangular channel having a narrow gap by changing the orientation of the copper test heater assembly in a pool of saturated water under the atmospheric pressure. The test parameters include both the gap sizes of 1, 2, 5 and 10 mm, and the surface orientation angles from the downward-facing position (180deg) to the vertical position (90deg), respectively. It was observed that the CHF generally decreases as the surface inclination angle increases and as the gap size decreases. However, in downward-facing position (180deg), somewhat differing results were detected relative to previous reports. For a certain gap size having a similar dimension with vapor layer thickness, more efficient heat transfer was detected and this may be interpreted by characteristic property such as the vapor layer thickness of water. In consistency with several studies reported in the literature, it was found that there exists a transition angle above that the CHF changes with a rapid slope. (author)

direct method of analysis of an isotropic rectangular plate direct

African Journals Online (AJOL)

eobe

This work evaluates the static analysis of an isotropic rectangular plate with various the static analysis ... method according to Ritz is used to obtain the total potential energy of the plate by employing the used to ..... for rectangular plates analysis, as the behavior of the ... results obtained by previous research work that used.

JET contributions to ITER R and D programme

International Nuclear Information System (INIS)

Gambier, D.J.; Tubbing, B.J.D.

1992-08-01

This report contains the Joint European Torus Project (JET) contributions to the International Thermonuclear Experimental Reactor (ITER) related research and development programme 1991-1992. The contributions, from many JET authors, were gathered in May/June 1992, so that the results of the 1991/92 experimental campaign could be fully incorporated. The contributions are ordered according to the description of tasks of the ITER-related Physics Research and Development programme, described in document ITER-TN-PH-0-7, issued April 30, 1991. (Author)

Tau method approximation of the Hubbell rectangular source integral

International Nuclear Information System (INIS)

Kalla, S.L.; Khajah, H.G.

2000-01-01

The Tau method is applied to obtain expansions, in terms of Chebyshev polynomials, which approximate the Hubbell rectangular source integral:I(a,b)=∫ b 0 (1/(√(1+x 2 )) arctan(a/(√(1+x 2 )))) This integral corresponds to the response of an omni-directional radiation detector situated over a corner of a plane isotropic rectangular source. A discussion of the error in the Tau method approximation follows

Experimental visualization coalesced interaction of sliding bubble near wall in vertical narrow rectangular channel

International Nuclear Information System (INIS)

Xu Jianjun; Chen Bingde; Wang Xiaojun

2011-01-01

The characteristic of the coalesced sliding bubble was visually observed by wide side and narrow side of the narrow rectangular channel using high speed digital camera. The results show that the coalesced time among the sliding bubbles is quick, and the new formation of coalesced bubble is not lift-off, and it continues to slide along the heated surface in low heat flux for the isolated bubble region. The influence region is about 2 times projected area of the sliding bubble when the sliding bubbles begin to interact. The sliding bubble velocities increase duo to the interaction among the bubbles, which contributes to enhance heat transfer of this region. Finally, the effect of coalesced interaction of growing bubble in the nucleation sites on bubble lift-off was discussed and analysed. (authors)

Jets in high energy nucleon-nucleon collisions

International Nuclear Information System (INIS)

Strugalski, Z.

1982-01-01

From the experimental studies of high-energy hardon-nucleon and nucleon-nucleon collisions, by means of nuclear targets applied as detectors, it follows that particles are produced via intermediate objects created first in a 2 → 2 type endoergic reaction. These objects, called generons, decay in flight into finally observed particles and resonances after their lifetime tausub(g) > or approximately 10 - 22 s. The jet structure of the outcome in nucleon-nucleon collisions is a simple and indispensable consequence of this particle production mechanism. The picture of the jet structure in the collision outcome observed in the CMS of the colliding nucleons depends on the energy of these nUcleons. New particle production scheme is proposed, which can be tested experimentally; corresponding simple relations between characteristics of colliding nucleons and of produced jets are proposed for a testing

Turbulent flow field structure of initially asymmetric jets

International Nuclear Information System (INIS)

Kim, Kyung Hoon; Kim, Bong Whan; Kim, Suk Woo

2000-01-01

The near field structure of round turbulent jets with initially asymmetric velocity distributions is investigated experimentally. Experiments are carried out using a constant temperature hot-wire anemomentry system to measure streamwise velocity in the jets. The measurements are undertaken across the jet at various streamwise stations in a range starting from the jet exit plane and up to a downstream location of twelve diameters. The experimental results include the distributions of mean and instantaneous velocities, vorticity field, turbulence intensity, and the Reynolds shear stresses. The asymmetry of the jet exit plane was obtained by using circular cross-section pipes with a bend upstream of the exit. Three pipes used here include a straight pipe, and 90 and 160 degree-bend pipes. Therefore, at the upstream of the pipe exit, secondary flow through the bend and mean streamwise velocity distribution could be controlled by changing the curvature of pipes. The jets into the atmosphere have two levels of initial velocity skewness in addition to an axisymmetric jet from a straight pipe. In case of the curved pipe, a six diameterlong straight pipe section follows the bend upstream of the exit. The Reynolds number based on the exit bulk velocity is 13,400. The results indicate that the near field structure is considerably modified by the skewness of an initial mean velocity distribution. As the skewness increases, the decay rate of mean velocity at the centerline also increases

Application of Uintah-MPM to shaped charge jet penetration of aluminum

International Nuclear Information System (INIS)

Burghardt, J; Leavy, B; Brannon, R; Guilkey, J; Xue, Z

2010-01-01

The capability of the generalized interpolation material point (GIMP) method in simulation of penetration events is investigated. A series of experiments was performed wherein a shaped charge jet penetrates into a stack of aluminum plates. Electronic switches were used to measure the penetration time history. Flash x-ray techniques were used to measure the density, length, radius and velocity of the shaped charge jet. Simulations of the penetration event were performed using the Uintah MPM/GIMP code with several different models of the shaped charge jet being used. The predicted penetration time history for each jet model is compared with the experimentally observed penetration history. It was found that the characteristics of the predicted penetration were dependent on the way that the jet data are translated to a discrete description. The discrete jet descriptions were modified such that the predicted penetration histories fell very close to the range of the experimental data. In comparing the various discrete jet descriptions it was found that the cumulative kinetic energy flux curve represents an important way of characterizing the penetration characteristics of the jet. The GIMP method was found to be well suited for simulation of high rate penetration events.

Jet fragmentation and predictions of the resummed perturbative QCD

Energy Technology Data Exchange (ETDEWEB)

Safonov, Alexei Nikolayevich [Univ. of Florida, Gainesville, FL (United States)

2001-01-01

This dissertation is dedicated to the experimental analysis of jet fragmentation, the process of formation of jets of particles produced in high-energy collisions, and to the comparison of the results to the predictions of resummed perturbative calculations within Quantum Chromodynamics.

Bifurcation in a buoyant horizontal laminar jet

Science.gov (United States)

Arakeri, Jaywant H.; Das, Debopam; Srinivasan, J.

2000-06-01

The trajectory of a laminar buoyant jet discharged horizontally has been studied. The experimental observations were based on the injection of pure water into a brine solution. Under certain conditions the jet has been found to undergo bifurcation. The bifurcation of the jet occurs in a limited domain of Grashof number and Reynolds number. The regions in which the bifurcation occurs has been mapped in the Reynolds number Grashof number plane. There are three regions where bifurcation does not occur. The various mechanisms that prevent bifurcation have been proposed.

Flow instability in laminar jet flames driven by alternating current electric fields

KAUST Repository

Kim, Gyeong Taek; Park, Daegeun; Cha, Min; Park, Jeong; Chung, Suk-Ho

2016-01-01

The effect of electric fields on the instability of laminar nonpremixed jet flames was investigated experimentally by applying the alternating current (AC) to a jet nozzle. We aimed to elucidate the origin of the occurrence of twin-lifted jet flames

Study of fuel powder formation in reactive coaxial jets

International Nuclear Information System (INIS)

Ablitzer, C.

1999-01-01

One step of the conversion of gaseous UF 6 to solid UO 2 by dry route is the formation of particles of UO 2 F 2 in a triple coaxial jet UF 6 /N 2 /H 2 O. The characteristics of resulting powder have an influence on the properties of final particles of UO 2 , and then on the quality of pellets of nuclear fuel. So a good control of this step of the process is of interest. This study deals with an experimental investigation and modelling of the influence of various parameters on particles obtained by reaction in a turbulent coaxial jet. For example, the influence of absolute and relative velocities of gases on particle size distributions has been investigated. Two kinds of experimental studies have been undertaken. First, the development of mixing layers in the near field of the jet has been evaluated with temperature measurements. Then, particle size distributions have been measured with e turbidimetric sensor, for particles obtained by hydrolysis of gaseous metallic chlorides (SnCl 4 , TiCl 4 ) in double and triple coaxial jets. A model has been proposed for mixing of gases and growth of particles. It takes into account the development of mixing layers, meso-mixing, micro-mixing and growth of particles through agglomeration. The influence of operating parameters, especially velocities, on experimental results appear to be different for TiCl 4 /H 2 O jets and SnCl 4 /H 2 O jets. In fact, a comparison of theoretical and experimental results shows that particles obtained by hydrolysis of TiCl 4 seem to grow mainly through agglomeration whereas another growth phenomenon may be involved for particles obtained by hydrolysis of SnCl 4 . (authors)

Development of New Correlation and Assessment of Correlations for Two-Phase Pressure Drop in Rectangular Microchannels

International Nuclear Information System (INIS)

Choi, Chi Woong; Yu, Dong In; Kim, Moo Hwan

2010-01-01

There are two kinds of models in two-phase pressured drop; homogeneous flow model and separated flow model. Many previous researchers have developed correlations for two-phase pressure drop in a microchannel. Most correlations were modified Lockhart and Martinelli's correlation, which was based on the separated flow model. In this study, experiments for adiabatic liquid water and nitrogen gas flow in rectangular microchannels were conducted to investigate two-phase pressure drop in the rectangular microchannels. Two-phase frictional pressure drop in the rectangular microchannels is highly related with flow regime. Homogeneous model with six two-phase viscosity models: Owen(21)'s, MacAdams(22)'s, Cicchitti et al.(23)'s, Dukler et al.(24)'s, Beattie and Whalley(25)'s, Lin et al.(26)'s models and six separated flow models: Lockhart and Martinelli(27)'s, Chisholm(31)'s, Zhang et al.(15)'s, Lee and Lee(5)'s, Moriyama and Inue(4)'s, Qu and Mudawar(8)'s models were assessed with our experimental data. The best two-phase viscosity model is Beattie and Whalley's model. The best separated flow model is Qu and Mudawar's correlation. Flow regime dependency in both homogeneous and separated flow models was observed. Therefore, new flow pattern based correlations for both homogeneous and separated flow models were individually proposed

On Hubbell's rectangular source integral

International Nuclear Information System (INIS)

Stalker, John

2001-01-01

The integral H(a,b)=∫ 0 b ∫ 0 a dx dy/(1+x 2 +y 2 ) arises naturally in the study of radiation from a rectangular source and has been studied by many authors. This paper introduces a new series expansion which is rapidly convergent for large a and b

Numerical analysis of jet breakup behavior using particle method

International Nuclear Information System (INIS)

Shibata, Kazuya; Koshizuka, Seiichi; Oka, Yoshiaki

2002-01-01

A continuous jet changes to droplets where jet breakup occurs. In this study, two-dimensional numerical analysis of jet breakup is performed using the MPS method (Moving Particle Semi-implicit Method) which is a particle method for incompressible flows. The continuous fluid surrounding the jet is neglected. Dependencies of the jet breakup length on the Weber number and the Froude number agree with the experiment. The size distribution of droplets is in agreement with the Nukiyama-Tanasawa distribution which has been widely used as an experimental correlation. Effects of the Weber number and the Froude number on the size distribution are also obtained. (author)

Usage of machine learning for the separation of electroweak and strong $Z_{\\gamma}$ production at the LHC experiments

OpenAIRE

Petukhov, A M; Yu Soldatov, E

2017-01-01

Separation of electroweak component from strong component of associated Zγ production on hadron colliders is a very challenging task due to identical final states of such processes. The only difference is the origin of two leading jets in these two processes. Rectangular cuts on jet kinematic variables from ATLAS/CMS 8 TeV Zγ experimental analyses were improved using machine learning techniques. New selection variables were also tested. The expected significance of separation for LHC experime...

Multiple-jet thermal mixing in a piping tee

International Nuclear Information System (INIS)

Lykoudis, P.S.; Hagar, R.C.

1979-01-01

Piping tees that are used to mix fluid streams at different temperatures are subjected to possibly severe thermal and mechanical stresses. There is reason to suspect that mixing in a piping tee could be improved by injecting the fluid streams into the tee through multiple jets. This paper reports the results of an experimental investigation of the effects of multiple-jet injection on mixing in a piping tee. The experimental work involves the measurement of the temperature fluctuation intensity with a hot-film sensor downstream of a simple 22.22-mm(7/8-in.)-diam tee with mixed multiple-jet injected hot and cold streams of water. The jets were provided by holes drilled in plates that partially blocked the inlet streams; 26 pairs of plates were investigated. The number of holes per plate varied from 1 to 51; the jet diameters ranged from 5 to 68% of the tee diameter. The inlet stream Reynolds number upstream of the jet plates was roughly 15 500 for each stream. The data indicated that the root mean square (rms) temperature fluctuation intensity measured at the tee outlet decreased dramatically as the jet plate cross-sectional area void fraction was decreased. When the jets emanating from the tee plates were misaligned, the reduction of the rms temperature fluctuation was not as high as when the jets were aligned. The rate of decay of the intensity downstream of the tee for most ofthe plates investigated was found to agree well with the -3/4 power decay law predicted by Corrsin's theory of scalar decay. However, unusual features in the intensity decay data were also observed, such as an increase of the intensity several diameters downstream before continuing to decay

Specific aspects of turbulent flow in rectangular ducts

Directory of Open Access Journals (Sweden)

Stanković Branislav D.

2017-01-01

Full Text Available The essential ideas of investigations of turbulent flow in a straight rectangular duct are chronologically presented. Fundamentally significant experimental and theoretical studies for mathematical modeling and numerical computations of this flow configuration are analyzed. An important physical aspect of this type of flow is presence of secondary motion in the plane perpendicular to the streamwise direction, which is of interest from both the engineering and the scientific viewpoints. The key facts for a task of turbulence modeling and optimal choice of the turbulence model are obtained through careful examination of physical mechanisms that generate secondary flows. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no.TR-33018: Increase in Energy and Ecology Efficiency of Processes in Pulverized Coal-Fired Furnace and Optimization of Utility Steam Boiler Air Pre-heater by Using In-House Developed Software Tools

Impedance of curved rectangular spiral coils around a conductive cylinder

Science.gov (United States)

Burke, S. K.; Ditchburn, R. J.; Theodoulidis, T. P.

2008-07-01

Eddy-current induction due to a thin conformable coil wrapped around a long conductive cylinder is examined using a second-order vector potential formalism. Compact closed-form expressions are derived for the self- and mutual impedances of curved rectangular spiral coils (i) in free space and (ii) when wrapped around the surface of the cylindrical rod. The validity of these expressions was tested against the results of a systematic series of experiments using a cylindrical Al-alloy rod and conformable coils manufactured using flexible printed-circuit-board technology. The theoretical expressions were in very good agreement with the experimental measurements. The significance of the results for eddy-current nondestructive inspection using flexible coils and flexible coil arrays is discussed.

Analysis of the rectangular resonator with butterfly MMI coupler using SOI

Science.gov (United States)

Kim, Sun-Ho; Park, Jun-Hee; Kim, Eudum; Jeon, Su-Jin; Kim, Ji-Hoon; Choi, Young-Wan

2018-02-01

We propose a rectangular resonator sensor structure with butterfly MMI coupler using SOI. It consists of the rectangular resonator, total internal reflection (TIR) mirror, and the butterfly MMI coupler. The rectangular resonator is expected to be used as bio and chemical sensors because of the advantages of using MMI coupler and the absence of bending loss unlike ring resonators. The butterfly MMI coupler can miniaturize the device compared to conventional MMI by using a linear butterfly shape instead of a square in the MMI part. The width, height, and slab height of the rib type waveguide are designed to be 1.5 μm, 1.5 μm, and 0.9 μm, respectively. This structure is designed as a single mode. When designing a TIR mirror, we considered the Goos-Hänchen shift and critical angle. We designed 3:1 MMI coupler because rectangular resonator has no bending loss. The width of MMI is designed to be 4.5 μm and we optimize the length of the butterfly MMI coupler using finite-difference time-domain (FDTD) method for higher Q-factor. It has the equal performance with conventional MMI even though the length is reduced by 1/3. As a result of the simulation, Qfactor of rectangular resonator can be obtained as 7381.

Jets in heavy ion collisions

International Nuclear Information System (INIS)

Nattrass, Christine

2017-01-01

High energy collisions of heavy nuclei permit the study of nuclear matter at temperatures and energy densities so high that the fundamental theory for strong interactions, QCD, predicts a phase transition to a plasma of quarks and gluons. This matter, called a Quark Gluon Plasma (QGP), has been studied experimentally for the last decade and has been observed to be a strongly interacting liquid with a low viscosity. High energy partons created early in the collision interact with the QGP and provide unique probes of its properties. Hard partons fragment into collimated sprays of particles called jets and have been studied through measurements of single particles, correlations between particles, and measurements of fully reconstructed jets. These measurements demonstrate partonic energy loss in the QGP and constrain the QGP’s properties. Measurements of the jet structure give insight into the mechanism of this energy loss. The information we have learned from studies of jets and challenges for the field will be reviewed. (paper)

Rectangular superpolynomials for the figure-eight knot 41

Science.gov (United States)

Kononov, Ya. A.; Morozov, A. Yu.

2017-11-01

We rewrite the recently proposed differential expansion formula for HOMFLY polynomials of the knot 41 in an arbitrary rectangular representation R = [rs] as a sum over all Young subdiagrams λ of R with surprisingly simple coefficients of the Z factors. Intriguingly, these coefficients are constructed from the quantum dimensions of symmetric representations of the groups SL(r) and SL(s) and restrict the summation to diagrams with no more than s rows and r columns. Moreover, the β-deformation to Macdonald dimensions yields polynomials with positive integer coefficients, which are plausible candidates for the role of superpolynomials for rectangular representations. Both the polynomiality and the positivity of the coefficients are nonobvious, nevertheless true. This generalizes the previously known formulas for symmetric representations to arbitrary rectangular representations. The differential expansion allows introducing additional gradings. For the trefoil knot 31, to which our results for the knot 41 are immediately extended, we obtain the so-called fourth grading of hyperpolynomials. The property of factorization in roots of unity is preserved even in the five-graded case.

Azimuthal critical heat flux in narrow rectangular channels

Energy Technology Data Exchange (ETDEWEB)

Kim, Yong Hoon; Noh, Sang Woo; Kim, Sung Joong; Suh, Kune Y. [Seoul National University, Seoul (Korea, Republic of)

2003-07-01

Tests were conducted to examine the critical heat flux (CHF) on the one-dimensional downward heating rectangular channel having a narrow gap by changing the orientation of the copper test heater assembly in a pool of saturated water under the atmospheric pressure. The test parameters include both the gap sizes of 1, 2, 5 and 10mm, and the surface orientation angles from the downward-facing position (180{sup o}) to the vertical position (90{sup o}), respectively. Also, the CHF experiments were performed for pool boiling with varying heater surface orientations in the unconfined space at the atmospheric pressure using the rectangular test section. It was observed that the CHF generally decreases as the surface inclination angle increases and as the gap size decreases. In consistency with several studies reported in the literature, it was found that there exists a transition angle above which the CHF changes with a rapid slope. An engineering correlation is developed for the CHF during natural convective boiling in the inclined, confined rectangular channels with the aid of dimensional analysis.

The effects of arbitrary injection angle and flow conditions on venturi-jet mixer

Directory of Open Access Journals (Sweden)

Sundararaj S.

2012-01-01

Full Text Available This paper describes the effect of jet injection angle, cross flow Reynolds number and velocity ratio on entrainment and mixing of jet with incompressible cross flow in venturi-jet mixer. Five different jet injection angles 45o, 60o, 90o, 125o, 135o are tested to evaluate the entrainment of jet and mixing performances of the mixer. Tracer concentration along the downstream of the jet injection, cross flow velocity, jet velocity and pressure drop across the mixer are determined experimentally to characterize the mixing performance of the mixer. The experiments show that the performance of a venturi-jet-mixer substantially improves at high injection angle and can be augmented still by increasing velocity ratio. The jet deflects much and penetrates less in the cross flow as the cross flow Reynolds number is increased. The effect could contribute substantially to the better mixing index with moderate pressure drop. Normalized jet profile, concentration decay, jet velocity profile are computed from equations of conservation of mass, momentum and concentration written in natural co-ordinate systems. The comparison between the experimental and numerical results confirms the accuracy of the simulations. Correlations for jet trajectory and entrainment ratio of the mixer are obtained by multivariate-linear regression analysis using power law.

Visualized study on specific points on demand curves and flow patterns in a single-side heated narrow rectangular channel

International Nuclear Information System (INIS)

Wang Junfeng; Huang Yanping; Wang Yanlin

2011-01-01

Highlights: → Specific points on the demand curve and flow patterns are visually studied. → Bubbly, churn, and annular flows were observed. → Onset of flow instability and bubbly-churn transition occurs at the same time. → The evolution of specific points and flow pattern transitions were examined. - Abstract: A simultaneous visualization and measurement study on some specific points on demand curves, such as onset of nucleate boiling (ONB), onset of significant void (OSV), onset of flow instability (OFI), and two-phase flow patterns in a single-side heated narrow rectangular channel, having a width of 40 mm and a gap of 3 mm, was carried out. New experimental approaches were adopted to identify OSV and OFI in a narrow rectangular channel. Under experimental conditions, the ONB could be predicted well by the Sato and Matsumura model. The OSV model of Bowring can reasonably predict the OSV if the single-side heated condition is considered. The OFI was close to the saturated boiling point and could be described accurately by Kennedy's correlation. The two-phase flow patterns observed in this experiment could be classified into bubbly, churn, and annular flow. Slug flow was never observed. The OFI always occurred when the bubbles at the channel exit began to coalesce, which corresponded to the beginning of the bubbly-churn transition in flow patterns. Finally, the evolution of specific points and flow pattern transitions were examined in a single-side heated narrow rectangular channel.

Separation control on the wing by jet actuators

Science.gov (United States)

Karyakin, O. M.; Nalivaiko, A. G.; Ustinov, M. V.; Flaxman, Ja. Sh.

2018-05-01

Use of jet actuators to eliminate flow separation is experimentally investigated on a straight wing with a NACA 0012 airfoil. It is shown that under the influence of synthetic jets the size of separation zone greatly reduces and the flow separation point displaces downstream. In addition, lift coefficient increases by more than 10%.

Swirl effect on flow structure and mixing in a turbulent jet

Science.gov (United States)

Kravtsov, Z. D.; Sharaborin, D. K.; Dulin, V. M.

2018-03-01

The paper reports on experimental study of turbulent transport in the initial region of swirling turbulent jets. The particle image velocimetry and planar laser-induced fluorescence techniques are used to investigate the flow structure and passive scalar concentration, respectively, in free air jet with acetone vapor. Three flow cases are considered, viz., non-swirling jets and swirling jets with and without vortex breakdown and central recirculation zone. Without vortex breakdown, the swirl is shown to promote jet mixing with surrounding air and to decrease the jet core length. The vortex core breakdown further enhances mixing as the jet core disintegrates at the nozzle exit.

Critical heat flux for free convection boiling in thin rectangular channels

International Nuclear Information System (INIS)

Cheng, Lap Y.; Tichler, P.R.

1991-01-01

A review of the experimental data on free convection boiling critical heat flux (CHF) in vertical rectangular channels reveals three mechanisms of burnout. They are the pool boiling limit, the circulation limit, and the flooding limit associated with a transition in flow regime from churn to annular flow. The dominance of a particular mechanism depends on the dimensions of the channel. Analytical models were developed for each free convection boiling limit. Limited agreement with data is observed. A CHF correlation, which is valid for a wide range of gap sizes, was constructed from the CHFs calculated according to the three mechanisms of burnout. 17 refs., 7 figs

Wakefield accelerator with hybrid plasma-dielectric structure of rectangular cross-section

International Nuclear Information System (INIS)

Kiselev, V.A.; Linnik, A.F.; Mirnyj, V.I.; Onishchenko, I.N.; Uskov, V.V.

2010-01-01

Increase of wakefield intensity at its excitation by a long train of relativistic electron bunches in the rectangular dielectric structure when it is filled with plasma of resonant density was experimentally observed. The first portion of the bunches, produced by electron linac 'Almaz-2', ionizes gas at atmospheric pressure so that plasma frequency becomes equal to bunch repetition frequency and to the frequency of principal Eigen mode of the dielectric structure. Excitation enhancement at such resonant conditions is being studied taking into account the improvement of bunch train propagation in the transit channel caused by charge compensation with plasma and the electrodynamics change of the dielectric structure at filling with plasma.

Natural Vibration Analysis of Clamped Rectangular Orthotropic Plates

Science.gov (United States)

dalaei, m.; kerr, a. d.

The natural vibrations of clamped rectangular orthotropic plates are analyzed using the extended Kantorovich method. The developed iterative scheme converges very rapidly to the final result. The obtained natural frequencies are evaluated for a square plate made of Kevlar 49 Epoxy and the obtained results are compared with those published by Kanazawa and Kawai, and by Leissa. The agreement was found to be very close. As there are no exact analytical solutions for clamped rectangular plates, the generated closed form expression for the natural modes, and the corresponding natural frequencies, are very suitable for use in engineering analyses.

Experimental investigation on the performance of an impinging jet solar air heater

Directory of Open Access Journals (Sweden)

T. Rajaseenivasan

2017-03-01

Full Text Available Investigation on an impinging jet solar air heater is performed and reported in this work. The air is supplied through an impinging jet pipe which contains the nozzles to distribute the air in the solar air heater. The air is released from the jet strikes the absorber plate which increases the heat transfer rate by creating turbulent flow in the collector. This study is focused on the parameters that affect the heat transfer characteristics and compared with conventional solar air heater. The system is examined by varying the angle of attack (0°, 10°, 20°, 30°, 60° and 90° and the nozzle diameter (3 mm, 5 mm and 7 mm in the air mass flow rate range of 0.012–0.016 kg/s. The study revealed that the highest performance is achieved with the 30° angle of attack, and the lowest performance is recorded with the 0°. The reduction in jet diameter increases the pressure loss in the collector. The better system performance is observed with the 5 mm diameter hole. The maximum thermal enhancement factor of 2.19 and efficiency of 55.8% are reached with the flow rate of 0.016 kg/s.

Experimental evidence for collisional shock formation via two obliquely merging supersonic plasma jets

Energy Technology Data Exchange (ETDEWEB)

Merritt, Elizabeth C., E-mail: emerritt@lanl.gov; Adams, Colin S. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); University of New Mexico, Albuquerque, New Mexico 87131 (United States); Moser, Auna L.; Hsu, Scott C., E-mail: scotthsu@lanl.gov; Dunn, John P.; Miguel Holgado, A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Gilmore, Mark A. [University of New Mexico, Albuquerque, New Mexico 87131 (United States)

2014-05-15

We report spatially resolved measurements of the oblique merging of two supersonic laboratory plasma jets. The jets are formed and launched by pulsed-power-driven railguns using injected argon, and have electron density ∼10{sup 14} cm{sup −3}, electron temperature ≈1.4 eV, ionization fraction near unity, and velocity ≈40 km/s just prior to merging. The jet merging produces a few-cm-thick stagnation layer, as observed in both fast-framing camera images and multi-chord interferometer data, consistent with collisional shock formation [E. C. Merritt et al., Phys. Rev. Lett. 111, 085003 (2013)].

A Green's function solution for a rectangular heat source on an infinite plate

International Nuclear Information System (INIS)

Bainbridge, B.L.

1989-01-01

The applications associated with a rectangular heat source on an infinite plate range from integrated circuits to thin film heat flux sensors on thin substrates. The particular problem from which the solution is developed concerns the use of a resistive strip for monitoring currents generated in circuits exposed to electromagnetic fields. The Green's function formulation is solved by using early and late time approximations for which analytical solutions can be derived. In this paper expressions are developed for three sets of boundary conditions and compared to the experimental performance of a physical device

Methods of Experimental Investigation of Cavitation in a Convergent - Divergent Nozzle of Rectangular Cross Section

Directory of Open Access Journals (Sweden)

Jablonská Jana

2016-08-01

Full Text Available Cavitation is a phenomenon with both positive and negative effects and with dynamic manifestations in hydraulic, food, chemical and other machinery. This article deals with the detection and dynamic behavior of cavitation clouds in water flows through a rectangular cross-section convergent-divergent nozzle. Cavitation was measured by methods applicable in engineering practice. Pressure, flow rate, noise, vibration, and amount of air dissolved in the liquid were measured and cavitation region was recorded with a high-speed camera. Evaluation of acquired images in connection with measured pressure pulsations and mechanical vibrations was performed with the use of the FFT method. In certain cases, dimensionless parameters were used to generalize the measurements. The results will be used to specify multiphase mathematical cavitation model parameters.

CFD analysis of premixed hydrogen/air combustion in an upright, rectangular shaped combustion chamber

International Nuclear Information System (INIS)

Gera, B.; Singh, R.K.; Vaze, K.K.

2014-01-01

Premixed hydrogen/air combustion in an upright, rectangular shaped combustion chamber has been performed numerically using commercial CFD code CFD-ACE+. The combustion chamber had dimensions 1 m X 0.024 m X 1 m. Simulations were carried out for 10% (v/v) hydrogen concentration for which experimental results were available. Effect of different boundary condition and ignition position on flame propagation was studied. Time dependent flame propagation in the chamber was predicted by CFD code. The computed transient flame propagation in the chamber was in good agreement with experimental results. The present work demonstrated that the available commercial CFD codes are capable of modeling hydrogen deflagration in a realistic manner. (author)

Experimental Investigation of Jet-Induced Mixing of a Large Liquid Hydrogen Storage Tank

Science.gov (United States)

Lin, C. S.; Hasan, M. M.; Vandresar, N. T.

1994-01-01

Experiments have been conducted to investigate the effect of fluid mixing on the depressurization of a large liquid hydrogen storage tank. The test tank is approximately ellipsoidal, having a volume of 4.89 m(exp 3) and an average wall heat flux of 4.2 W/m(exp 2) due to external heat input. A mixer unit was installed near the bottom of the tank to generate an upward directed axial jet flow normal to the liquid-vapor interface. Mixing tests were initiated after achieving thermally stratified conditions in the tank either by the introduction of hydrogen gas into the tank or by self-pressurization due to ambient heat leak through the tank wall. The subcooled liquid jet directed towards the liquid-vapor interface by the mixer induced vapor condensation and caused a reduction in tank pressure. Tests were conducted at two jet submergence depths for jet Reynolds numbers from 80,000 to 495,000 and Richardson numbers from 0.014 to 0.52. Results show that the rate of tank pressure change is controlled by the competing effects of subcooled jet flow and the free convection boundary layer flow due to external tank wall heating. It is shown that existing correlations for mixing time and vapor condensation rate based on small scale tanks may not be applicable to large scale liquid hydrogen systems.

Top Jets at the LHC

Energy Technology Data Exchange (ETDEWEB)

Almeida, L.G.; Lee, S.J.; Perez, G.; Sung, I.; Virzi, J.

2008-10-06

We investigatethe reconstruction of high pT hadronically-decaying top quarksat the Large Hadron Collider. One of the main challenges in identifying energetictop quarks is that the decay products become increasingly collimated. This reducesthe efficacy of conventional reconstruction methods that exploit the topology of thetop quark decay chain. We focus on the cases where the decay products of the topquark are reconstructed as a single jet, a"top-jet." The most basic"top-tag" methodbased on jet mass measurement is considered in detail. To analyze the feasibility ofthe top-tagging method, both theoretical and experimental aspects of the large QCDjet background contribution are examined. Based on a factorization approach, wederive a simple analytic approximation for the shape of the QCD jet mass spectrum.We observe very good agreement with the Monte Carlo simulation. We consider high pT tt bar production in the Standard Model as an example, and show that our theoretical QCD jet mass distributions can efficiently characterize the background via sideband analyses. We show that with 25 fb-1 of data, our approach allows us to resolve top-jets with pT _> 1 TeV, from the QCD background, and about 1.5 TeV top-jets with 100 fb-1, without relying on b-tagging. To further improve the significancewe consider jet shapes (recently analyzed in 0807.0234 [hep-ph]), which resolve thesubstructure of energy flow inside cone jets. A method of measuring the top quarkpolarization by using the transverse momentum of the bottom quark is also presented.The main advantages of our approach are: (i) the mass distributions are driven byfirst principle calculations, instead of relying solely on Monte Carlo simulation; (ii) for high pT jets (pT _> 1 TeV), IR-safe jet shape variables are robust against detectorresolution effects. Our analysis can be applied to other boosted massive particlessuch as the electroweak gauge bosons and the Higgs.

The effect of thermal conductance of vertical walls on natural convection in a rectangular enclosure

International Nuclear Information System (INIS)

Kikuchi, Y.; Yoshino, A.; Taii, K.

2004-01-01

This paper deals with the experimental results of natural convective heat transfer in a rectangular water layer bounded by vertical walls of different thermal conductance. The vertical walls were made of copper or stainless steel. A minimum was observed in the horizontal distribution of temperature near the heating wall since a secondary reverse flow occurred outside the boundary layer. For copper case the experimental results of Nusselt number agreed well with calculations under an isothermal wall condition. For stainless steel case, however, the measured values were lower than the calculations since a three-dimensional effect appeared in convection due to non-uniformity in wall temperature. (author)

Friction coefficient of an intact free liquid jet moving in air

Science.gov (United States)

Comiskey, P. M.; Yarin, A. L.

2018-04-01

Here, we propose a novel method of determining the friction coefficient of intact free liquid jets moving in quiescent air. The middle-size jets of this kind are relevant for such applications as decorative fountains, fiber-forming, fire suppression, agriculture, and forensics. The present method is based on measurements of trajectories created using a straightforward experimental apparatus emulating such jets at a variety of initial inclination angles. Then, the trajectories are described theoretically, accounting for the longitudinal traction imposed on such jets by the surrounding air. The comparison of the experimental data with the theoretical predictions shows that the results can be perfectly superimposed with the friction coefficient {C_{{fd}}}=5R{e_d}^{{ - 1/2 ± 0.05}}, in the 621 ≤ R{e_d} ≤ 1289 range, with Red being the Reynolds number based on the local cross-sectional diameter of the jet. The results also show that the farthest distance such jets can reach corresponds to the initial inclination angle α =35° which is in agreement with already published data.

Simulation Of Gas Focused Liquid Jets

OpenAIRE

Zahoor, Rizwan

2018-01-01

The main aim of dissertation is to develop an experimentally verified computational fluid dynamic (CFD) model of micron-sized liquid jet, produced by an injection molded Gas Dynamic Virtual Nozzle (GDVN). In these nozzles, liquid jets are efficiently orientedly transporting mass and momentum. They are produced by intelligently projecting hydrodynamic focusing effect from a high-speed stream of a co-flowing lower density and lower viscosity gas on a stream of liquid from a feeding capillary. L...

Searching possibilities of a composite structure of quarks from the jet studies in the ATLAS experiment: physical and experimental aspects

International Nuclear Information System (INIS)

Brette, Ph.

1996-01-01

This thesis presents the searching possibilities of a composite structure of quark from the jet studies in the ATLAS experiment. ATLAS is one of the major detectors on the LHC, the next proton-proton collider at CERN. The general physic framework of the quark compositeness is first introduced, the its expected search from the contact terms in the channel 2 → 2 is explained. After a description of the ATLAS apparatus and of the prototype of the hadronic scintillating tiles calorimeter, various experimental properties of the hadron calorimeter with respect to the jet measurement are studied. The effect of the non-linearity of the calorimeter response is particularly discussed, including the light red out with the photomultipliers. The laser monitoring system enables a full control of the gain stability of the photomultipliers and of their non-linearity for large signals. Its design and the measured performance are shown. Finally, by considering both the expected performances of the ATLAS detector and the theoretical uncertainties, it appears that the compositeness scale controlled at the LHC, for quarks, should reach 15 to 20 TeV depending upon the luminosity, from jet measurement up to 3 TeV. (author)

Joining of Aluminium Alloy Sheets by Rectangular Mechanical Clinching

International Nuclear Information System (INIS)

Abe, Y.; Mori, K.; Kato, T.

2011-01-01

A mechanical clinching has the advantage of low running costs. However, the joint strength is not high. To improve the maximum load of the joined sheets by a mechanical clinching, square and rectangular mechanical clinching were introduced. In the mechanical clinching, the two sheets are mechanically joined by forming an interlock between the lower and upper sheets by the punch and die. The joined length with the interlock was increased by the rectangular punch and die. The deforming behaviours of the sheets in the mechanical clinching were investigated, and then the interlock in the sheets had distribution in the circumference of the projection. Although the interlocks were formed in both projection side and diagonal, the interlock in the diagonal was smaller because of the long contact length between the lower sheet and the die cavity surface. The maximum load of the joined sheets by the rectangular mechanical clinching was two times larger than the load by the round mechanical clinching.

Experimental study of stratified jet by simultaneous measurements of velocity and density fields

Science.gov (United States)

Xu, Duo; Chen, Jun

2012-07-01

Stratified flows with small density difference commonly exist in geophysical and engineering applications, which often involve interaction of turbulence and buoyancy effect. A combined particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) system is developed to measure the velocity and density fields in a dense jet discharged horizontally into a tank filled with light fluid. The illumination of PIV particles and excitation of PLIF dye are achieved by a dual-head pulsed Nd:YAG laser and two CCD cameras with a set of optical filters. The procedure for matching refractive indexes of two fluids and calibration of the combined system are presented, as well as a quantitative analysis of the measurement uncertainties. The flow structures and mixing dynamics within the central vertical plane are studied by examining the averaged parameters, turbulent kinetic energy budget, and modeling of momentum flux and buoyancy flux. At downstream, profiles of velocity and density display strong asymmetry with respect to its center. This is attributed to the fact that stable stratification reduces mixing and unstable stratification enhances mixing. In stable stratification region, most of turbulence production is consumed by mean-flow convection, whereas in unstable stratification region, turbulence production is nearly balanced by viscous dissipation. Experimental data also indicate that at downstream locations, mixing length model performs better in mixing zone of stable stratification regions, whereas in other regions, eddy viscosity/diffusivity models with static model coefficients represent effectively momentum and buoyancy flux terms. The measured turbulent Prandtl number displays strong spatial variation in the stratified jet.

Effect of aspect ratio on relationship between flow resistance and flow regime of two-phase flow in rectangular channel

International Nuclear Information System (INIS)

Yan Chaoxing; Yan Changqi; Sun Licheng; Xing Dianchuan; Wang Yang

2013-01-01

On the basis of visual observation, the effects of aspect ratio on relationship between flow resistance and flow regime were investigated experimentally for two-phase flow in three rectangular channels with the same cross-section width of 43 mm and different heights of 1.41, 3 and 10 mm, respectively. According to the criteria in terms of restriction factor C o , the former two channels belong to narrow channel, whereas the last one is conventional channel. The experimental results show that the two-phase pressure drops in rectangular channel with different aspect ratios have different variation trends with the increase of the gas velocity. For the 10 mm channel, the gravitational pressure drop makes the major percentage of total pressure drop at low gas velocity while the frictional pressure drop is dominant for the 1.41 mm and 3 mm channels. With the increase of the gas flow rate, the frictional pressure drop contributes more to total pressure drop. The range of churn flow can be distinguished from its pressure drop characteristic in 10 mm channel. (authors)

Proceedings of the Jet Noise Workshop

Science.gov (United States)

Huff, Dennis (Compiler)

2001-01-01

Jet noise has been a major problem for aircraft for nearly 50 years. There has been considerable research performed around the world aimed at identifying ways to reduce jet noise. This work was first intended for turbojet aircraft and later extended to low bypass ratio turbofans. Many of the people who performed this pioneering research have retired or are no longer active in aeroacoustics. After so many years of work in jet noise, it is a challenge to piece together the history of its development through existing publications due to the large volume of documents. It is possible to forget important developments from the past as new researchers tackle similar problems. Therefore, a jet noise workshop was organized by the AeroAcoustics Research Consortium (AARC) with the intent of reviewing research that has been done by experts throughout the world. The forum provided a unique opportunity for current researchers to hear the diverse views from world experts on issues related to jet noise modeling and interpretation of experimental data.

77 FR 3497 - Light-Walled Rectangular Pipe and Tube From Taiwan

Science.gov (United States)

2012-01-24

... Rectangular Pipe and Tube From Taiwan Determination On the basis of the record \\1\\ developed in the subject... order on light-walled rectangular pipe and tube from Taiwan would be likely to lead to continuation or recurrence of material injury to an industry in the United States within a reasonably foreseeable time. \\1...

Characteristics of strongly-forced turbulent jets and non-premixed jet flames

Energy Technology Data Exchange (ETDEWEB)

Lakshminarasimhan, K.; Ezekoye, O.A. [University of Texas at Austin, Department of Mechanical Engineering, Austin, TX (United States); Clemens, N.T. [University of Texas at Austin, Department of Aerospace Engineering and Engineering Mechanics, Austin, TX (United States)

2006-10-15

Previous researchers have demonstrated that strong pulsations of the fuel flow rate can significantly reduce the flame length and luminosity of laminar/transitional non-premixed jet flames. The physical mechanisms responsible for these changes are investigated experimentally in acoustically-forced jet flows where the peak velocity fluctuations are up to eight times the mean flow velocity. Both reacting and non-reacting flows were studied and Reynolds numbers, based on the mean flow properties, ranged from 800 to 10,000 (corresponding to peak Reynolds numbers of 1,450-23,000), and forcing frequencies ranged from 290 to 1,140 Hz. Both the first and second organ-pipe resonance modes of the fuel delivery tube were excited to obtain these frequencies. An analysis of the acoustic forcing characteristics within the resonance tube is provided in order to understand the source of the high amplitude forcing. Flow visualization of jets with first resonant forcing confirms the presence of large-scale coherent vortices and strong reverse flow near the exit of the fuel tube. With second-resonant forcing, however, vortices are not emitted from the tube as they are drawn back into the fuel tube before they can fully form. Increased fine-scale turbulence is associated with both resonant cases, but particularly at second resonance. The power spectra of the velocity fluctuations for a resonantly pulsed jet show the presence of an inertial subrange indicating that the flow becomes fully turbulent even for mean-Reynolds-number jets that are nominally laminar. It is shown that these pulsed jet flows exhibit strong similarities to synthetic jets and that the Strouhal number, based on the maximum velocity at the fuel tube exit, is the dominant parameter for scaling these flows. The Strouhal number determines the downstream location where the coherent vortices breakdown, and is found to provide better collapse of flame length data (both current and previous) than other parameters that have

Validation Plan of Turbulence Models for Internal Gas Flow Analysis in a Heated Rectangular Riser Duct

Energy Technology Data Exchange (ETDEWEB)

Kim, Sin-Yeob; Shin, Dong-Ho; Park, Goon-Cherl; Cho, Hyoung Kyu [Seoul National Univ., Seoul (Korea, Republic of); Kim, Chan-Soo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

VHTR being developed at Korea Atomic Energy Research Institute adopts an air-cooled Reactor Cavity Cooling System (RCCS) incorporating rectangular riser channels to remove the afterheat emitted from the reactor vessel. Because the performance of RCCS is determined by heat removal rate through the RCCS riser, it is important to understand the heat transfer phenomena in the RCCS riser to ensure the safety of the reactor. In the mixed convection, due to the buoyance force induced by temperature and density differences, local flow structure and heat transfer mode near the heated wall have significantly dissimilar characteristics from both forced convection and free convection. In this study, benchmark calculation was conducted to reproduce the previous statements that V2F turbulence model can capture the mixed convection phenomena with the Shehata's experimental data. Then, the necessity of the model validation for the mixed convection phenomena was confirmed with the CFD analyses for the geometry of the prototype RCCS riser. For the purpose of validating the turbulence models for mixed convection phenomena in the heated rectangular riser duct, validation plan with three experimental tests was introduced. Among them, the flow visualization test facility with preserved cross-section geometry was introduced and a preliminary test result was shown.

Immunotoxicity evaluation of jet a jet fuel in female rats after 28-day dermal exposure.

Science.gov (United States)

Mann, Cynthia M; Peachee, Vanessa L; Trimmer, Gary W; Lee, Ji-Eun; Twerdok, Lorraine E; White, Kimber L

2008-01-01

The potential for jet fuel to modulate immune functions has been reported in mice following dermal, inhalation, and oral routes of exposure; however, a functional evaluation of the immune system in rats following jet fuel exposure has not been conducted. In this study potential effects of commercial jet fuel (Jet A) on the rat immune system were assessed using a battery of functional assays developed to screen potential immunotoxic compounds. Jet A was applied to the unoccluded skin of 6- to 7-wk-old female Crl:CD (SD)IGS BR rats at doses of 165, 330, or 495 mg/kg/d for 28 d. Mineral oil was used as a vehicle to mitigate irritation resulting from repeated exposure to jet fuel. Cyclophosphamide and anti-asialo GM1 were used as positive controls for immunotoxic effects. In contrast to reported immunotoxic effects of jet fuel in mice, dermal exposure of rats to Jet A did not result in alterations in spleen or thymus weights, splenic lymphocyte subpopulations, immunoglobulin (Ig) M antibody-forming cell response to the T-dependent antigen, sheep red blood cells (sRBC), spleen cell proliferative response to anti-CD3 antibody, or natural killer (NK) cell activity. In each of the immunotoxicological assays conducted, the positive control produced the expected results, demonstrating the assay was capable of detecting an effect if one had occurred. Based on the immunological parameters evaluated under the experimental conditions of the study, Jet A did not adversely affect immune responses of female rats. It remains to be determined whether the observed difference between this study and some other studies reflects a difference in the immunological response of rats and mice or is the result of other factors.

On the shock cell structure and noise of supersonic jets

Science.gov (United States)

Tam, C. K. W.; Jackson, J. A.

1983-01-01

A linear solution modeling the shock cell structure of an axisymmetric supersonic jet operated at off-design conditions is developed by the method of multiple-scales. The model solution takes into account the gradual spatial change of the mean flow in the downstream direction. Turbulence in the mixing layer of the jet has the tendency of smoothing out the sharp velocity and density gradients induced by the shocks. To simulate this effect, eddy viscosity terms are incorporated in the model. It is known that the interaction between the quasi-periodic shock cells and the downstream propagating large turbulence structures in the mixing layer of the jet is responsible for the generation of broadband shock associated noise. Experimentally, the dominant part of this noise has been found to originate from the part of the jet near the end of the potential core. Calculated shock cell spacing at the end of the jet core according to the present model is used to estimate the peak frequencies of the shock associated noise for a range of observation angles. Very favorable agreement with experimental measurements is found.

Perron-Frobenius Theorem for Rectangular Tensors and Directed Hypergraphs

OpenAIRE

Lu, Linyuan; Yang, Arthur L. B.; Zhao, James J. Y.

2018-01-01

For any positive integers $r$, $s$, $m$, $n$, an $(r,s)$-order $(n,m)$-dimensional rectangular tensor ${\\cal A}=(a_{i_1\\cdots i_r}^{j_1\\cdots j_s}) \\in ({\\mathbb R}^n)^r\\times ({\\mathbb R}^m)^s$ is called partially symmetric if it is invariant under any permutation on the lower $r$ indexes and any permutation on the upper $s$ indexes. Such partially symmetric rectangular tensor arises naturally in studying directed hypergraphs. Ling and Qi [Front. Math. China, 2013] first studied the $(p,q)$-...

Technical and Scientific Aspects of the JET Trace-Tritium Experimental Campaign

International Nuclear Information System (INIS)

Jones, T.T.C.; Brennan, D; Pearce, R.J.H.; Stork, D.; Zastrow, K.-D.; Balshaw, N.; Bell, A.C.; Bertalot, L.; Boyer, H.; Butcher, P.R.; Challis, C.D.; Ciric, D.; Clarke, R.; Conroy, S.; Darke, A.C.; Davies, N.; Edlington, T.; Ericsson, G.; Gibbons, C.; Hackett, L.J.; Haupt, T.; Hitchin, M.; Kaye, A.S.; King, R.; Kiptily, V.G.; Knipe, S.; Lawrence, G.; Lobel, R.; Mason, A.; Morgan, P.D.; Patel, B.; Popovichev, S.; Stamp, M.; Surrey, E.; Terrington, A.; Worth, L.; Young, D.

2005-01-01

The JET Trace Tritium (TTE) programme marked the first use of tritium in experiments under the managerial control of UKAEA, which operates the JET Facility on behalf of EFDA. The introduction of tritium into the plasma by gas fuelling and neutral beam injection, even in trace quantities, required the mobilisation of gram-quantities of tritium gas from the Active Gas Handling System (AGHS) product storage units into the supply lines connected to the torus gas valve and the neutral beam injectors. All systems for DT gas handling, recovery and reprocessing were therefore recommissioned and operating procedures re-established, involving extensive operations staff training. The validation of Key Safety Related Equipment (KSRE) is described with reference to specific examples. The differences between requirements for TTE and full DT operations are shown to be relatively small. The scientific motivation for TTE, such as the possibility to obtain high-quality measurements in key areas such as fuel-ion transport and fast ion dynamics, is described, and the re-establishment and development of JET's 14MeV neutron diagnostic capability for TTE and future DT campaigns are outlined. Some scientific highlights from the TTE campaign are presented

Augmented Beta rectangular regression models: A Bayesian perspective.

Science.gov (United States)

Wang, Jue; Luo, Sheng

2016-01-01

Mixed effects Beta regression models based on Beta distributions have been widely used to analyze longitudinal percentage or proportional data ranging between zero and one. However, Beta distributions are not flexible to extreme outliers or excessive events around tail areas, and they do not account for the presence of the boundary values zeros and ones because these values are not in the support of the Beta distributions. To address these issues, we propose a mixed effects model using Beta rectangular distribution and augment it with the probabilities of zero and one. We conduct extensive simulation studies to assess the performance of mixed effects models based on both the Beta and Beta rectangular distributions under various scenarios. The simulation studies suggest that the regression models based on Beta rectangular distributions improve the accuracy of parameter estimates in the presence of outliers and heavy tails. The proposed models are applied to the motivating Neuroprotection Exploratory Trials in Parkinson's Disease (PD) Long-term Study-1 (LS-1 study, n = 1741), developed by The National Institute of Neurological Disorders and Stroke Exploratory Trials in Parkinson's Disease (NINDS NET-PD) network. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Active control of the jet in coaxial arrangement

Directory of Open Access Journals (Sweden)

Šafařík P.

2013-04-01

Full Text Available An axisymmetric jet flow, issuing as a fully developed flow from a long straight pipe at Re = 1600 and 5500, was actively controlled by an annular synthetic jet. The Pitot tube, hot-wire anemometry (CTA and flow visualization were used for an experimental investigation of the flow control. The working fluid was air. The effect of varying Strouhal number (St = (0.18÷1.94 on a width and entrainment of the main jet flow was studied. It was found that the main jet is the most sensitive to the actuation at St = 0.28÷0.60 and St = 0.18, for Re = 1600 and Re = 5500, respectively.

The JET Project Scientific and technical developments 1976

International Nuclear Information System (INIS)

1977-01-01

The JET (Joint European Torus) Project is fully described in EUR 5516e (EUR-JET-R5) 'The JET Project - Design Proposal'. This report describes developments in the project from the stage described in EUR 5516e until late in 1976. An introductory chapter describes the present state of the project and subsequent chapters deal in detail with the following topics: experimental programme aspects; vacuum vessel, pumping system, activation studies; toroidal field coils and mechanical structure; poloidal field system; assembly and maintenance; power supplies; control and data acquisition system; site and buildings

Experimental study of the orientation of three-jet events in e+e- annihilation at PETRA

International Nuclear Information System (INIS)

Braunschweig, W.; Gerhards, R.; Kirschfink, F.J.; Martyn, H.U.; Kolanoski, H.; Bowler, M.G.; Burrows, P.N.; Cashmore, R.; Veitch, M.E.; Brandt, S.; Holder, M.; Labarga, L.; Caldwell, A.; Muller, D.; Ritz, S.; Strom, D.; Takashima, M.; Wu Saulan; Zobernig, G.

1990-01-01

The full TASSO data have been used to study the orientation of three-jet events in e + e - annihilation. The polar angle distributions of the normal to the three-jet plane as well as the polar angle distribution of the most energetic jet have been measured as a function of the thrust cut-off used to select the three-jet sample. The data corrected for radiation and detector effects are compared to QCD predictions and fair agreement is found. As a consistency check we also present measurements of the azimuthal correlations between the lepton and hadron planes. A significant azimuthal dependence is found, consistent again with the QCD predictions. (orig.)

Modeling the interference of vortex-induced vibration and galloping for a slender rectangular prism

Science.gov (United States)

Mannini, Claudio; Massai, Tommaso; Marra, Antonino Maria

2018-04-01

Several bluff bodies in an airflow, such as rectangular cylinders with moderate side ratio, in particular conditions of mass and damping can experience the interference of vortex-induced vibration (VIV) and galloping. This promotes a combined instability, which one may call "unsteady galloping", with peculiar features and possibly large vibration amplitudes in flow speed ranges where no excitation is predicted by classical theories. The mathematical model proposed between the 70's and the 80's by Prof. Y. Tamura to simulate this phenomenon was considered here for the case study of a two-dimensional rectangular cylinder with a side ratio of 1.5, having the shorter section side perpendicular to the smooth airflow. This wake-oscillator model relies on the linear superposition of the unsteady wake force producing VIV excitation and the quasi-steady force that is responsible for galloping. The model formulation was slightly modified, and the way to determine a crucial parameter was changed, revealing a previously unexplored behavior of the equations. In the present form, the model is able to predict the dynamic response of the rectangular cylinder with a satisfactory qualitative and, to a certain extent, quantitative agreement with the experimental data, although the limitations of the present approach are clearly highlighted in the paper. The mathematical modeling of unsteady galloping and the analysis of the results offer a deep insight into this complicated phenomenon and its nonlinear features. The model also represents a useful engineering tool to estimate the vibration of a structure or structural element for which the interference of VIV and galloping is envisaged.

Monte Carlo study on the properties of gluon and quark jets

CERN Document Server

Kun Shi Zhang; Mei Ling Yu; Lian Shou Liu

2002-01-01

The 3-jet events produced in e/sup +/e/sup -/ collisions at 91.2 GeV have been studied using Monte Carlo method. After applying two angular cuts the three angles between the jets are used to identify the individual jet in 3-jet events. The energy distributions of the three jets, the mean particle multiplicities, mean transverse momenta of the three jets in equal energy bins and their distributions have been analyzed. Comparing with the corresponding results from the quark jets in 2-jet events, a simple method to select gluon and quark jets from 3-jet events is obtained. The properties of the gluon and quark jets being selected using the introduced method are in qualitative agreement with the expectations of perturbative QCD. The ratio of the mean multiplicity between quark and gluon jets, /sub gluon///sub quark/, has been calculated. The results, again, agree with the experimental results from SLD, OPAL, ALEPH, and DELPHI Collaborations, indicating that the method proposed to select gluon and quark jets from ...

Tickling a high speed round jet

Science.gov (United States)

Arakeri, Vijay; Krothapalli, Anjaneyulu; Siddavaram, Vikram; Alkislar, Mehmet

2001-11-01

We have experimentally studied the effect of tickling a Mach 0.9 round jet with a set of microjets.Two dimensional velocity field measurements with PIV show a significant reduction in the turbulent intensities in the developing region of the jet with the activation of the microjets.Quantitatively,the axial and normal turbulence intensities are reduced by about 15respectively;even a larger effect is found on the magnitude of the correlation of axial and normal fluctuation intensities with a reduction of almost 40possible with a mass flow rate of the microjets being only about one percent of the main jet mass flow rate and hence justifying the use of the term `tickling`.The above findings are difficult to explain on the basis of stability considerations since there is very little change in the mean profile.Physically,the observed effect could be due to the alteration of the large eddy structures,which are so natural to a round jet,by the presence of the microjets.Exact nature of this interaction may be clarified with three dimensional PIV studies.It is expected that the tickling of the jet done as presently could have a favourable reflection in the aeroacoustics characteristics of the main jet.

Effects of anisotropic properties on bursting behavior of rectangular cup with a V-notch

Energy Technology Data Exchange (ETDEWEB)

Kim, Jeong Tai [R and D Center, TERA Co. Ltd., Seoul (Korea, Republic of); Kim, Sang Mok [R and D Center, Hyosung Power and Industrial Systems PG, Changwon (Korea, Republic of); Kang, Beom Soo [Dept. of Aerospace Engineering, Pusan National University, Busan (Korea, Republic of); Ku, Tae Wan [Engineering Research Center of Innovative Technology on Advanced Forming, Pusan National University, Busan (Korea, Republic of)

2016-09-15

Effects of mechanical anisotropic properties on bursting failure and its pressure of rectangular deep-drawn cup fabricated by using AA3005-H14 thin sheet are investigated to utilize for electrolyte container of lithium-ion secondary batteries. The V-notch shape with a depth of 0.1 mm and an angle of 20.0 degrees is defined on the rectangular cup, which has a thickness of 0.20 mm on the major surface and that of 0.30 mm on the minor surface. With the measured mechanical properties by uni-axial tensile tests and the defined V-notch geometry, a series of numerical prediction models considering isotropic, planar and normal anisotropic characteristics, are built-up and the bursting simulations are performed. Thereafter, the bursting fracture behavior is investigated by adopting ductile fracture criterion proposed by Cockcroft and Latham. The results predicted for the planar and the normal anisotropic models show that the bursting fracture pressure is well matched to 0.400 MPa, and the isotropic and the planar anisotropic models present a bursting fracture height of about 4.95 mm and 4.92 mm, respectively. A series of experimental investigations are undertaken to verify the bursting deformation that had been predicted. The bursting pressure and its height during experimental verifications are shown to be in good agreement with each variation of about 5.88% and roughly 0.20% with respect to the numerical results obtained using the planar anisotropic model.

Machine learning in jet physics

CERN Multimedia

CERN. Geneva

2018-01-01

High energy collider experiments produce several petabytes of data every year. Given the magnitude and complexity of the raw data, machine learning algorithms provide the best available platform to transform and analyse these data to obtain valuable insights to understand Standard Model and Beyond Standard Model theories. These collider experiments produce both quark and gluon initiated hadronic jets as the core components. Deep learning techniques enable us to classify quark/gluon jets through image recognition and help us to differentiate signals and backgrounds in Beyond Standard Model searches at LHC. We are currently working on quark/gluon jet classification and progressing in our studies to find the bias between event generators using domain adversarial neural networks (DANN). We also plan to investigate top tagging, weak supervision on mixed samples in high energy physics, utilizing transfer learning from simulated data to real experimental data.

Jet mass spectra in Higgs+one jet at NNLL

International Nuclear Information System (INIS)

Jouttenus, Teppo T.; Stewart, Iain W.; Waalewijn, Wouter J.

2013-02-01

The invariant mass of a jet is a benchmark variable describing the structure of jets at the LHC. We calculate the jet mass spectrum for Higgs plus one jet at the LHC at next-to-next-to-leading logarithmic (NNLL) order using a factorization formula. At this order, the cross section becomes sensitive to perturbation theory at the soft m 2 jet /p jet T scale. Our calculation is exclusive and uses the 1-jettiness global event shape to implement a veto on additional jets. The dominant dependence on the jet veto is removed by normalizing the spectrum, leaving residual dependence from non-global logarithms depending on the ratio of the jet mass and jet veto variables. For our exclusive jet cross section these non-global logarithms are parametrically smaller than in the inclusive case, allowing us to obtain a complete NNLL result. Results for the dependence of the jet mass spectrum on the kinematics, jet algorithm, and jet size R are given. Using individual partonic channels we illustrate the difference between the jet mass spectra for quark and gluon jets. We also study the effect of hadronization and underlying event on the jet mass in Pythia. To highlight the similarity of inclusive and exclusive jet mass spectra, a comparison to LHC data is presented.

Jetting from impact of a spherical drop with a deep layer

Science.gov (United States)

Zhang, Li; Toole, Jameson; Fazzaa, Kamel; Deegan, Robert; Deegan Group Team; X-Ray Science Division, Advanced Photon Source Collaboration

2011-11-01

We performed an experimental study of jets during the impact of a spherical drop with a deep layer of same liquid. Using high speed optical and X-ray imaging, we observe two types of jets: the so-called ejecta sheet which emerges almost immediately after impact and the lamella which emerges later. For high Reynolds number the two jets are distinct, while for low Reynolds number the two jets combine into a single continuous jet. We also measured the emergence time, speed, and position of the ejecta sheet and found simple scaling relations for these quantities.

Pressure drop of magnetohydrodynamic two-phase annular flow in rectangular channel

International Nuclear Information System (INIS)

Kumamaru, Hiroshige; Fujiwara, Yoshiki; Ogita, Kenji

1999-01-01

Numerical calculations have been performed on magnetohydrodynamic (MHD) two-phase annular flow in a rectangular channel with a small aspect ratio, i.e.a small ratio of the channel side perpendicular to the applied magnetic field and the side parallel to the field. Results of the present calculation agree nearly with Inoue et al.'s experimental results in the region of large liquid Reynolds numbers and large Hartmann numbers. Calculation results also show that the pressure drop ratio, i.e. the ratio of pressure drop of two-phase flow to that of single-phase flow under the same liquid flow rate and applied magnetic field, becomes lower than ∼0.02 for conditions of a fusion reactor plant. (author)

Extended Horizontal Jet Drilling for EGS applications in Petrothermal Environments

Science.gov (United States)

Hahn, Simon; Duda, Mandy; Stoeckhert, Ferdinand; Wittig, Volker; Bracke, Rolf

2017-04-01

Extended Horizontal Jet Drilling for EGS applications in Petrothermal Environments S. Hahn, M. Duda, F. Stoeckhert, V. Wittig, R. Bracke International Geothermal Centre Bochum High pressure water jet drilling technologies are widely used in the drilling industry. Especially in geothermal and hard rock applications, horizontal (radial) jet drilling is, however, confronted with several limitations like lateral length, hole size and steerability. In order to serve as a serious alternative to conventional stimulation techniques these high pressure jetting techniques are experimentally investigated to gain fundamental knowledge about the fluid-structure interaction, to enhance the rock failing process and to identify the governing drilling parameters. The experimental program is divided into three levels. In a first step jetting experiments are performed under free surface conditions while logging fluid pressures, flow speeds and extracted rock volume. All process parameters are quantified with a self-developed jet-ability index and compared to the rock properties (density, porosity, permeability, etc.). In a second step experiments will be performed under pressure-controlled conditions. A test bench is currently under construction offering the possibility to assign an in-situ stress field to the specimen while penetrating the rock sample with a high pressure water jet or a radial jet drilling device. The experimental results from levels 1 and 2 allow to identify the governing rock failure mechanisms and to correlate them with physical rock properties and limited reservoir conditions. Results of the initial tests do show a clear dependency of achievable penetration depth on the interaction of jetting and rock parameters and an individual threshold of the nozzle outlet velocity can be noticed in order to successfully penetrate different formation types. At level 3 jetting experiments will be performed at simulated reservoir conditions corresponding to 5.000 m depth (e

Noise from Aft Deck Exhaust Nozzles: Differences in Experimental Embodiments

Science.gov (United States)

Bridges, James E.

2014-01-01

Two embodiments of a rectangular nozzle on an aft deck are compared. In one embodiment the lower lip of the nozzle was extended with the sidewalls becoming triangles. In a second embodiment a rectangular nozzle was fitted with a surface that fit flush to the lower lip and extended outward from the sides of the nozzle, approximating a semi-infinite plane. For the purpose of scale-model testing, making the aft deck an integral part of the nozzle is possible for relatively short deck lengths, but a separate plate model is more flexible, accounts for the expanse of deck to the sides of the nozzle, and allows the nozzle to stand off from the deck. Both embodiments were tested and acoustic far-field results were compared. In both embodiments the extended deck introduces a new noise source, but the amplitude of the new source was dependent upon the span (cross-stream dimension) of the aft deck. The noise increased with deck length (streamwise dimension), and in the case of the beveled nozzle it increased with increasing aspect ratio. In previous studies of slot jets in wings it was noted that the increased noise from the extended aft deck appears as a dipole at the aft deck trailing edge, an acoustic source type with different dependence on velocity than jet mixing noise. The extraneous noise produced by the aft deck in the present studies also shows this behavior both in directivity and in velocity scaling.

Jet stability in the lithium fall reactor

International Nuclear Information System (INIS)

Kang, S.W.

1978-01-01

A preliminary analysis has been made of the various hydrodynamic aspects involved in the stability of a liquid-lithium jet in a laser-fusion reactor, which comprises a part of LLL's laser fusion power-generation concept. Various physical factors that may affect the jet breakup are delineated, and some approximate calculations are performed to determine their relative influences. Areas of uncertainty are pointed out, along with plans for experimental verification or further theoretical analysis

Jet angularity measurements for single inclusive jet production

Science.gov (United States)

Kang, Zhong-Bo; Lee, Kyle; Ringer, Felix

2018-04-01

We study jet angularity measurements for single-inclusive jet production at the LHC. Jet angularities depend on a continuous parameter a allowing for a smooth interpolation between different traditional jet shape observables. We establish a factorization theorem within Soft Collinear Effective Theory (SCET) where we consistently take into account in- and out-of-jet radiation by making use of semi-inclusive jet functions. For comparison, we elaborate on the differences to jet angularities measured on an exclusive jet sample. All the necessary ingredients for the resummation at next-to-leading logarithmic (NLL) accuracy are presented within the effective field theory framework. We expect semiinclusive jet angularity measurements to be feasible at the LHC and we present theoretical predictions for the relevant kinematic range. In addition, we investigate the potential impact of jet angularities for quark-gluon discrimination.

Jet mass spectra in Higgs+one jet at NNLL

Energy Technology Data Exchange (ETDEWEB)

Jouttenus, Teppo T.; Stewart, Iain W. [Massachusetts Institute of Technology, Cambridge, MA (United States). Center for Theoretical Physics; Tackmann, Frank J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Waalewijn, Wouter J. [California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics

2013-02-15

The invariant mass of a jet is a benchmark variable describing the structure of jets at the LHC. We calculate the jet mass spectrum for Higgs plus one jet at the LHC at next-to-next-to-leading logarithmic (NNLL) order using a factorization formula. At this order, the cross section becomes sensitive to perturbation theory at the soft m{sup 2}{sub jet}/p{sup jet}{sub T} scale. Our calculation is exclusive and uses the 1-jettiness global event shape to implement a veto on additional jets. The dominant dependence on the jet veto is removed by normalizing the spectrum, leaving residual dependence from non-global logarithms depending on the ratio of the jet mass and jet veto variables. For our exclusive jet cross section these non-global logarithms are parametrically smaller than in the inclusive case, allowing us to obtain a complete NNLL result. Results for the dependence of the jet mass spectrum on the kinematics, jet algorithm, and jet size R are given. Using individual partonic channels we illustrate the difference between the jet mass spectra for quark and gluon jets. We also study the effect of hadronization and underlying event on the jet mass in Pythia. To highlight the similarity of inclusive and exclusive jet mass spectra, a comparison to LHC data is presented.

Monte Carlo study on the properties of gluon and quark jets

CERN Document Server

Zhang Kun Shi; Yu Mei Ling; LianShouLiu

2002-01-01

The 3-jet events produced in e sup + e sup - collisions at 91.2 GeV have been studied using Monte Carlo method. After applying two angular cuts the three angles between the jets are used to identify the individual jet in 3-jet events. The energy distributions of the three jets, the mean particle multiplicities, mean transverse momenta of the three jets in equal energy bins and their distributions have been analyzed. Comparing with the corresponding results from the quark jets in 2-jet events, a simple method to select gluon and quark jets from 3-jet events is obtained. The properties of the gluon and quark jets being selected using the introduced method are in qualitative agreement with the expectations of perturbative QCD. The ratio of the mean multiplicity between quark and gluon jets, sub g sub l sub u sub o sub n / sub q sub u sub q sub r sub k , has been calculated. The results, again, agree with the experimental results from SLD, OPAL, ALEPH and DELPHI Collaborations, indicating that the method propose...

JET joint undertaking. Annual report 1978

International Nuclear Information System (INIS)

1979-02-01

This document is intended for information only and should not be used as a technical reference. After an introductive part on the controlled nuclear fusion research and an historical survey of the JET project, are presented: the JET joint undertaking (members of council and committee...) with its administration (finance, personnel, external relations), and the scientific and technical department with its divisions for systems (experimental, magnet, plasma, assembly, power supplies, control and data acquisition, and site and building). In appendix is described the Euratom fusion research programme

Particle image velocimetry measurements of the flow in the converging region of two parallel jets

Energy Technology Data Exchange (ETDEWEB)

Wang, Huhu, E-mail: huhuwang@tamu.edu; Lee, Saya, E-mail: sayalee@tamu.edu; Hassan, Yassin A., E-mail: y-hassan@tamu.edu

2016-09-15

Highlights: • The flow behaviors in the converging region were non-intrusively investigated using PIV. • The PIV results using two measuring scales and LDV data matched very well. • Significant momentum transfer was observed in the merging region right after the merging point. • Instantaneous vector field revealed characteristic interacting patterns of the jets. - Abstract: The interaction between parallel jets plays a critical role in determining the characteristics of the momentum and heat transfer in the flow. Specifically for next generation VHTR, the output temperature will be about 900 °C, and any thermal oscillations will create safety issues. The mixing variations of the coolants in the reactor core may influence these power oscillations. Numerous numerical tools such as computational fluid dynamics (CFD) simulations have been used to support the reactor design. The validation of CFD method is important to ensure the fidelity of the calculations. This requires high-fidelity, qualified benchmark data. Particle image velocimetry (PIV), a non-intrusive measuring technique, was used to provide benchmark data for resolving a simultaneous flow field in the converging region of two submerged parallel jets issued from rectangular channels. The jets studied in this work had an equal discharge velocity at room temperature. The turbulent characteristics including the distributions of mean velocities, turbulence intensities, Reynolds stresses and z-component vorticity were studied. The streamwise mean velocity measured by PIV and LDV were compared, and they agreed very well.

Jet photoproduction at HERA

International Nuclear Information System (INIS)

Frixione, S.

1997-01-01

We compute various kinematical distributions for one-jet and two-jet inclusive photoproduction at HERA. Our results are accurate to next-to-leading order in QCD. We use the subtraction method for the cancellation of infrared singularities. We perform a thorough study of the reliability of QCD predictions; in particular, we consider the scale dependence of our results and discuss the cases when the perturbative expansion might break down. We also deal with the problem of the experimental definition of the pointlike and hadronic components of the incident photon, and briefly discuss the sensitivity of QCD predictions upon the input parameters of the calculation, like α S and the parton densities. (orig.)

Finite element analysis of crack growth from rectangular notch in mixed mode loading

International Nuclear Information System (INIS)

Mohd Rawi Mohd Zin

2002-01-01

The direction of crack growth from rectangular notch for ductile material is determined in this paper. The ductile material is assumed to exhibit the elastic-plastic behaviour. In the model, the crack is assumed to start when the J-integral fracture criterion exceeded the critical value during the application of load and the crack tip propagated to a priori. The direction of the crack is characterised by maximum principles stress criterion and the mechanism of crack propagation is simulated by deleted element technique. The model is validated with experimental results and it shows good agreement. (Author)

Flow transition criteria of a liquid jet into a liquid pool

Energy Technology Data Exchange (ETDEWEB)

Saito, Shimpei, E-mail: s1630195@u.tsukuba.ac.jp [Graduate School of Systems and Information Engineering, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Abe, Yutaka [Faculty of Engineering, Information and Systems, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Koyama, Kazuya [Reactor Core and Safety Design Department, Mitsubishi FBR Systems, Inc., 2-34-17 Jingumae, Shibuya, Tokyo 150-0001 (Japan)

2017-04-15

Highlights: • Jet breakup and droplet formation in immiscible liquid-liquid systems was studied experimentally. • The observed jet breakup behavior was classified into characteristic regimes. • The droplet size distribution was analyzed using image processing. • The variation of droplet size was compared with available melt-jet experiments. • Extrapolation to the expected SFR conditions implied that most of the hydrodynamic conditions would be the atomization regime. - Abstract: To better understand the fundamental interactions between melt jet and coolant during a core-disruptive accident at a sodium-cooled fast reactor, the jet breakup and droplet formation in immiscible liquid-liquid systems were studied experimentally. Experiments using two different pairs of test fluids were carried out at isothermal conditions. The observed jet breakup behavior was classified into characteristic regimes based on the classical Ohnesorge classification in liquid-gas systems. The variation in breakup length obtained in the present liquid-liquid system was similar to that in a liquid-gas system. The droplet size distribution in each breakup regime was analyzed using image processing and droplet formation via pinch-off, satellite formation, and entrainment was observed. The measured droplet size was compared with those available from melt jet experiments. Based on the observation and analysis results, the breakup regimes were organized on a dimensionless operating diagram, with the derived correlations representing the criteria for regime boundaries of a liquid-liquid system. Finally, the experimental data were extrapolated to the expected conditions of a sodium-cooled fast reactor. From this, it was implied that most of the hydrodynamic conditions during an accident would be close to the atomization regime, in which entrainment is the dominant process for droplet formation.

three dimensional photoelastic investigations on thick rectangular

African Journals Online (AJOL)

user

1983-09-01

Sep 1, 1983 ... Thick rectangular plates are investigated by means of three-dimensional photoelasticity ... a thin plate theory and a higher order thick plate theory. 1. ..... number of fringes lest the accuracy of the results will be considerably.

Performance evaluation of a natural-convection solar air-heater with a rectangular-finned absorber plate

International Nuclear Information System (INIS)

Fakoor Pakdaman, M.; Lashkari, A.; Basirat Tabrizi, H.; Hosseini, R.

2011-01-01

This paper deals with an experimental investigation to evaluate different thermal characteristics of a natural-convection flat-plate solar air-heater with longitudinal rectangular fins array. Having determined the thermal performance of the system a Nusselt number correlation is presented for such finned duct devices. In the presented empirical model which may have industrial applications, solar radiation and ambient temperature have been considered as independent parameters. Other characteristics of the system such as different dimensionless variables, plates and outflow temperatures, efficiency, and mass flow rate have been empirically modeled based on these variables. The particular difference in this study in comparison with the other similar studies is the presentation of an empirical model for rectangular-finned solar air-heaters. This model proposes design concepts and rules of thumb, and demonstrates the calculations of the design parameters. Based on the order of magnitude analysis, solar radiation has been found to be the main parameter which characterizes the thermal behavior of the system. Besides, exergy analysis has been carried out, and optimum conditions in which the system has the highest performance have been determined.

Solar-thermal jet pumping for irrigation

Science.gov (United States)

Clements, L. D.; Dellenback, P. A.; Bell, C. A.

1980-01-01

This paper describes a novel concept in solar powered irrigation pumping, gives measured performance data for the pump unit, and projected system performance. The solar-thermal jet pumping concept is centered around a conventional jet eductor pump which is commercially available at low cost. The jet eductor pump is powered by moderate temperature, moderate pressure Refrigerant-113 vapor supplied by a concentrating solar collector field. The R-113 vapor is direct condensed by the produced water and the two fluids are separated at the surface. The water goes on to use and the R-113 is repressurized and returned to the solar field. The key issue in the solar-thermal jet eductor concept is the efficiency of pump operation. Performance data from a small scale experimental unit which utilizes an electrically heated boiler in place of the solar field is presented. The solar-thermal jet eductor concept is compared with other solar irrigation concepts and optimal application situations are identified. Though having lower efficiencies than existing Rankine cycle solar-thermal irrigation systems, the mechanical and operational simplicity of this concept make it competitive with other solar powered irrigation schemes.

Quark jets, gluon jets and the three-gluon vertex