VibroCav : Hydrodynamic Vibration and Cavitation Technology

NARCIS (Netherlands)

Bakker, T.W.

2012-01-01

Vibration and cavitation can be generated in many ways and serve many useful purposes. This study describes physical aspects of useful vibration and cavitation for a broad spectrum of applications at atmospheric or elevated pressures. After a review of available devices, hydrodynamic

Modeling of hydrodynamic cavitation reactors: a unified approach

NARCIS (Netherlands)

Moholkar, V.S.; Pandit, A.B.

2001-01-01

An attempt has been made to present a unified theoretical model for the cavitating flow in a hydrodynamic cavitation reactor using the nonlinear continuum mixture model for two-phase flow as the basis. This model has been used to describe the radial motion of bubble in the cavitating flow in two

An experimental investigation of hydrodynamic cavitation in micro-Venturis

Science.gov (United States)

Mishra, Chandan; Peles, Yoav

2006-10-01

The existence of hydrodynamic cavitation in the flow of de-ionized water through micro-Venturis has been witnessed in the form of traveling bubble cavitation and fully developed streamer bubble/supercavitation, and their mechanisms have been discussed. High-speed photography and flow visualization disclose inchoate cavitation bubbles emerging downstream from the micro-Venturi throat and the presence of a single streamer bubble/supercavity, which is equidistant from the micro device walls. The supercavity initiates inside the diffuser section and extends until the microchannel exit and proceeds to bifurcate the incoming flow. This article strives to provide numerical data and experimental details of hydrodynamic cavitation taking place within micro-Venturis.

The issue of cavitation number value in studies of water treatment by hydrodynamic cavitation.

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Šarc, Andrej; Stepišnik-Perdih, Tadej; Petkovšek, Martin; Dular, Matevž

2017-01-01

Within the last years there has been a substantial increase in reports of utilization of hydrodynamic cavitation in various applications. It has came to our attention that many times the results are poorly repeatable with the main reason being that the researchers put significant emphasis on the value of the cavitation number when describing the conditions at which their device operates. In the present paper we firstly point to the fact that the cavitation number cannot be used as a single parameter that gives the cavitation condition and that large inconsistencies in the reports exist. Then we show experiments where the influences of the geometry, the flow velocity, the medium temperature and quality on the size, dynamics and aggressiveness of cavitation were assessed. Finally we show that there are significant inconsistencies in the definition of the cavitation number itself. In conclusions we propose a number of parameters, which should accompany any report on the utilization of hydrodynamic cavitation, to make it repeatable and to enable faster progress of science and technology development. Copyright © 2016 Elsevier B.V. All rights reserved.

Biodiesel production through hydrodynamic cavitation and performance testing

Energy Technology Data Exchange (ETDEWEB)

Pal, Amit; Verma, Ashish; Kachhwaha, S.S.; Maji, S. [Department of Mechanical Engineering, Delhi College of Engineering, Bawana Road, Delhi 110042 (India)

2010-03-15

This paper presents the details of development of a biodiesel production test rig based on hydrodynamic cavitation followed by results of experimental investigation carried out on a four cylinder, direct injection water cooled diesel engine operating on diesel and biodiesel blend of Citrullus colocyntis (Thumba) oil. The experiment covers a wide range of engine rpm. Results show that biodiesel of Thumba oil produced through hydrodynamic cavitation technique can be used as an alternative fuel with better performance and lower emissions compared to diesel. The most significant conclusions are that (1) Biodiesel production through hydrodynamic cavitation technique seems to be a simple, efficient, time saving, eco-friendly and industrially viable process. (2) 30% biodiesel blend of Thumba oil shows relatively higher brake power, brake thermal efficiency, reduced bsfc and smoke opacity with favourable p-{theta} diagram as compared to diesel. (author)

Combined treatment technology based on synergism between hydrodynamic cavitation and advanced oxidation processes.

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Gogate, Parag R; Patil, Pankaj N

2015-07-01

The present work highlights the novel approach of combination of hydrodynamic cavitation and advanced oxidation processes for wastewater treatment. The initial part of the work concentrates on the critical analysis of the literature related to the combined approaches based on hydrodynamic cavitation followed by a case study of triazophos degradation using different approaches. The analysis of different combinations based on hydrodynamic cavitation with the Fenton chemistry, advanced Fenton chemistry, ozonation, photocatalytic oxidation, and use of hydrogen peroxide has been highlighted with recommendations for important design parameters. Subsequently degradation of triazophos pesticide in aqueous solution (20 ppm solution of commercially available triazophos pesticide) has been investigated using hydrodynamic cavitation and ozonation operated individually and in combination for the first time. Effect of different operating parameters like inlet pressure (1-8 bar) and initial pH (2.5-8) have been investigated initially. The effect of addition of Fenton's reagent at different loadings on the extent of degradation has also been investigated. The combined method of hydrodynamic cavitation and ozone has been studied using two approaches of injecting ozone in the solution tank and at the orifice (at the flow rate of 0.576 g/h and 1.95 g/h). About 50% degradation of triazophos was achieved by hydrodynamic cavitation alone under optimized operating parameters. About 80% degradation of triazophos was achieved by combination of hydrodynamic cavitation and Fenton's reagent whereas complete degradation was achieved using combination of hydrodynamic cavitation and ozonation. TOC removal of 96% was also obtained for the combination of ozone and hydrodynamic cavitation making it the best treatment strategy for removal of triazophos. Copyright © 2014 Elsevier B.V. All rights reserved.

Hydrodynamic Cavitation-Assisted Synthesis of Nanocalcite

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Shirish H. Sonawane

2010-01-01

Full Text Available A systematic study was made on the synthesis of nanocalcite using a hydrodynamic cavitation reactor. The effects of various parameters such as diameter and geometry of orifice, CO2 flow rate, and Ca(OH2 concentration were investigated. It was observed that the orifice diameter and its geometry had significant effect on the carbonation process. The reaction rate was significantly faster than that observed in a conventional carbonation process. The particle size was significantly affected by the reactor geometry. The results showed that an orifice with 5 holes of 1 mm size resulted in the particle size reduction to 37 nm. The experimental investigation reveals that hydrodynamic cavitation may be more energy efficient.

Degradation of organic wastewater by hydrodynamic cavitation combined with acoustic cavitation.

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Yi, Chunhai; Lu, Qianqian; Wang, Yun; Wang, Yixuan; Yang, Bolun

2018-05-01

In this paper, the decomposition of Rhodamine B (RhB) by hydrodynamic cavitation (HC), acoustic cavitation (AC) and the combination of these individual methods (HAC) have been investigated. The degradation of 20 L RhB aqueous solution was carried out in a self-designed HAC reactor, where hydrodynamic cavitation and acoustic cavitation could take place in the same space simultaneously. The effects of initial concentration, inlet pressure, solution temperature and ultrasonic power were studied and discussed. Obvious synergies were found in the HAC process. The combined method achieved the best conversion, and the synergistic effect in HAC was even up to 119% with the ultrasonic power of 220 W in a treatment time of 30 min. The time-independent synergistic factor based on rate constant was introduced and the maximum value reached 40% in the HAC system. Besides, the hybrid HAC method showed great superiority in energy efficiency at lower ultrasonic power (88-176 W). Therefore, HAC technology can be visualized as a promising method for wastewater treatment with good scale-up possibilities. Copyright © 2018 Elsevier B.V. All rights reserved.

Efficient inactivation of MS-2 virus in water by hydrodynamic cavitation.

Science.gov (United States)

Kosel, Janez; Gutiérrez-Aguirre, Ion; Rački, Nejc; Dreo, Tanja; Ravnikar, Maja; Dular, Matevž

2017-11-01

The aim of this study was to accurately quantify the impact of hydrodynamic cavitation on the infectivity of bacteriophage MS2, a norovirus surrogate, and to develop a small scale reactor for testing the effect of hydrodynamic cavitation on human enteric viruses, which cannot be easily prepared in large quantities. For this purpose, 3 mL scale and 1 L scale reactors were constructed and tested. Both devices were efficient in generating hydrodynamic cavitation and in reducing the infectivity of MS2 virus. Furthermore, they reached more than 4 logs reductions of viral infectivity, thus confirming the scalability of hydrodynamic cavitation for this particular application. As for the mechanism of page inactivation, we suspect that cavitation generated OH - radicals formed an advanced oxidation process, which could have damaged the host's recognition receptors located on the surface of the bacteriophage. Additional damage could arise from the high shear forces inside the cavity. Moreover, the effectiveness of the cavitation was higher for suspensions containing low initial viral titers that are in similar concentration to the ones found in real water samples. According to this, cavitation generators could prove to be a useful tool for treating virus-contaminated wastewaters in the future. Copyright © 2017 Elsevier Ltd. All rights reserved.

Control of hydrodynamic cavitation using ultrasonic

Science.gov (United States)

Chatterjee, Dhiman; Arakeri, Vijay H.

2003-11-01

Hydrodynamic cavitation is known to have many harmful effects like surface damage and generation of noise. We investigated the use of ultrasonics to control traveling bubble cavitation. Ultrasonic pressure field, produced by a piezoelectric crystal, was applied to modify the nuclei size distribution. Effects of continuous-wave (CW) and pulsed excitations were studied. At low dissolved gas content the CW-mode performed better than the pulsed one, whereas for high gas content the pulsed one was more effective. The dominant mechanisms were Bjerknes force and rectified diffusion in these two cases. Simultaneous excitation by two crystals in CW and pulsed modes was seen to control cavitation better.

Hydrodynamic cavitation as a novel approach for delignification of wheat straw for paper manufacturing.

Science.gov (United States)

Badve, Mandar P; Gogate, Parag R; Pandit, Aniruddha B; Csoka, Levente

2014-01-01

The present work deals with application of hydrodynamic cavitation for intensification of delignification of wheat straw as an essential step in the paper manufacturing process. Wheat straw was first treated with potassium hydroxide (KOH) for 48 h and subsequently alkali treated wheat straw was subjected to hydrodynamic cavitation. Hydrodynamic cavitation reactor used in the work is basically a stator and rotor assembly, where the rotor is provided with indentations and cavitational events are expected to occur on the surface of rotor as well as within the indentations. It has been observed that treatment of alkali treated wheat straw in hydrodynamic cavitation reactor for 10-15 min increases the tensile index of the synthesized paper sheets to about 50-55%, which is sufficient for paper board manufacture. The final mechanical properties of the paper can be effectively managed by controlling the processing parameters as well as the cavitational parameters. It has also been established that hydrodynamic cavitation proves to be an effective method over other standard digestion techniques of delignification in terms of electrical energy requirements as well as the required time for processing. Overall, the work is first of its kind application of hydrodynamic cavitation for enhancing the effectiveness of delignification and presents novel results of significant interest to the paper and pulp industry opening an entirely new area of application of cavitational reactors. Copyright © 2013 Elsevier B.V. All rights reserved.

Degradation of dichlorvos using hydrodynamic cavitation based treatment strategies.

Science.gov (United States)

Joshi, Ravi K; Gogate, Parag R

2012-05-01

The degradation of an aqueous solution of dichlorvos, a commonly used pesticide in India, has been systematically investigated using hydrodynamic cavitation reactor. All the experiments have been carried out using a 20 ppm solution of commercially available dichlorvos. The effect of important operating parameters such as inlet pressure (over a range 3-6 bar), temperature (31 °C, 36 °C and 39 °C) and pH (natural pH = 5.7 and acidic pH = 3) on the extent of degradation has been investigated initially. It has been observed that an optimum value of pressure gives maximum degradation whereas low temperature and pH of 3 are favorable. Intensification studies have been carried out using different additives such as hydrogen peroxide, carbon tetrachloride, and Fenton's reagent. Use of hydrogen peroxide and carbon tetrachloride resulted in the enhancement of the extent of degradation at optimized conditions but significant enhancement was obtained with the combined use of hydrodynamic cavitation and Fenton's chemistry. The maximum extent of degradation as obtained by using a combination of hydrodynamic cavitation and Fenton's chemistry was 91.5% in 1h of treatment time. The present work has conclusively established that hydrodynamic cavitation in combination with Fenton's chemistry can be effectively used for the degradation of dichlorvos. Copyright © 2011 Elsevier B.V. All rights reserved.

Statistical analysis of hydrodynamic cavitation events

Science.gov (United States)

Gimenez, G.; Sommer, R.

1980-10-01

The frequency (number of events per unit time) of pressure pulses produced by hydrodynamic cavitation bubble collapses is investigated using statistical methods. The results indicate that this frequency is distributed according to a normal law, its parameters not being time-evolving.

Limitations of the Weissler reaction as a model reaction for measuring the efficiency of hydrodynamic cavitation.

Science.gov (United States)

Morison, K R; Hutchinson, C A

2009-01-01

The Weissler reaction in which iodide is oxidised to a tri-iodide complex (I(3)(-)) has been widely used for measurement of the intensity of ultrasonic and hydrodynamic cavitation. It was used in this work to compare ultrasonic cavitation at 24 kHz with hydrodynamic cavitation using two different devices, one a venturi and the other a sudden expansion, operated up to 8.7 bar. Hydrodynamic cavitation had a maximum efficiency of about 5 x 10(-11) moles of I(3)(-) per joule of energy compared with the maximum of almost 8 x 10(-11) mol J(-1) for ultrasonic cavitation. Hydrodynamic cavitation was found to be most effective at 10 degrees C compared with 20 degrees C and 30 degrees C and at higher upstream pressures. However, it was found that in hydrodynamic conditions, even without cavitation, I(3)(-) was consumed at a rapid rate leading to an equilibrium concentration. It was concluded that the Weissler reaction was not a good model reaction for the assessment of the effectiveness of hydrodynamic cavitation.

Fluid dynamics of acoustic and hydrodynamic cavitation in hydraulic power systems

Science.gov (United States)

Ferrari, A.

2017-03-01

Cavitation is the transition from a liquid to a vapour phase, due to a drop in pressure to the level of the vapour tension of the fluid. Two kinds of cavitation have been reviewed here: acoustic cavitation and hydrodynamic cavitation. As acoustic cavitation in engineering systems is related to the propagation of waves through a region subjected to liquid vaporization, the available expressions of the sound speed are discussed. One of the main effects of hydrodynamic cavitation in the nozzles and orifices of hydraulic power systems is a reduction in flow permeability. Different discharge coefficient formulae are analysed in this paper: the Reynolds number and the cavitation number result to be the key fluid dynamical parameters for liquid and cavitating flows, respectively. The latest advances in the characterization of different cavitation regimes in a nozzle, as the cavitation number reduces, are presented. The physical cause of choked flows is explained, and an analogy between cavitation and supersonic aerodynamic flows is proposed. The main approaches to cavitation modelling in hydraulic power systems are also reviewed: these are divided into homogeneous-mixture and two-phase models. The homogeneous-mixture models are further subdivided into barotropic and baroclinic models. The advantages and disadvantages of an implementation of the complete Rayleigh-Plesset equation are examined.

Kidney stone erosion by micro scale hydrodynamic cavitation and consequent kidney stone treatment.

Science.gov (United States)

Perk, Osman Yavuz; Şeşen, Muhsincan; Gozuacik, Devrim; Koşar, Ali

2012-09-01

The objective of this study is to reveal the potential of micro scale hydrodynamic bubbly cavitation for the use of kidney stone treatment. Hydrodynamically generated cavitating bubbles were targeted to the surfaces of 18 kidney stone samples made of calcium oxalate, and their destructive effects were exploited in order to remove kidney stones in in vitro experiments. Phosphate buffered saline (PBS) solution was used as the working fluid under bubbly cavitating conditions in a 0.75 cm long micro probe of 147 μm inner diameter at 9790 kPa pressure. The surface of calcium oxalate type kidney stones were exposed to bubbly cavitation at room temperature for 5 to 30 min. The eroded kidney stones were visually analyzed with a high speed CCD camera and using SEM (scanning electron microscopy) techniques. The experiments showed that at a cavitation number of 0.017, hydrodynamic bubbly cavitation device could successfully erode stones with an erosion rate of 0.31 mg/min. It was also observed that the targeted application of the erosion with micro scale hydrodynamic cavitation may even cause the fracture of the kidney stones within a short time of 30 min. The proposed treatment method has proven to be an efficient instrument for destroying kidney stones.

Comparison of Nannochloropsis sp. cells disruption between hydrodynamic cavitation and conventional extraction

Directory of Open Access Journals (Sweden)

Setyawan Martomo

2018-01-01

Full Text Available Biodiesel production from microalgae is one of the solution of the future energy problem, but its production cost is still high. One of the costly stages of this process is the lipid extraction process. It can be reduced by microalgae cell disruption. One of the mechanical method to cell disruption with the lowest energy requirement is hydrodynamic cavitation. This aim of this study is to evaluate the distribution coefficient and the mass transfer coefficient value of lipid extraction of Nannochloropsis sp. assisted by hydrodynamic cavitation and compare with conventional extraction. The hydrodynamic cavitation extraction was done at 34 °C, 1 atm. The conventional extraction was done at 34 °C, 1 atm with stirring speed 260 and 1000 rpm. The experimental result shows that the distribution coefficient dependent on the temperature with the values for 50, 44, 38 and 34 °C were 0.502, 0.394, 0.349, and 0.314 respectively. And it was according to Van’ Hoff equation with the values of ΔH° was 20.718 kJ/mol and ΔS° was 58.05 J/mol/K. The hydrodynamic cavitation extraction was faster than conventional. The mass transfer coefficient values for hydrodynamic cavitation, conventional 260 rpm and 1000 rpm were 7.373, 0.534 and 0.121 1/s respectively.

Effects of Hydrodynamic Cavitation of a Restriction Orifice on Crud-like Deposits

International Nuclear Information System (INIS)

Kim, Seong Man; Lee, Seung Won; Park, Sung Dae; Kang, Sarah; Seo, Han; Bang, In Cheol

2011-01-01

Axial Offset Anomaly (AOA) referring to an unexpected neutron flux depression is also known as Crud Induced Power Shift (CIPS). Fuel assemblies removed from an AOA core has shown a thick porous deposition layer of crud on fuel clad surface. The deposition layer was induced by precipitation reactions of both boron species and crud during sub-cooled nucleate boiling. Therefore, to resolve the AOA issues, a fuel cleaning technology using ultrasonic cavitation has been developed by EPRI and applied to the domestic NPPs by KNF. However, the performance of crud removal during maintenance of NPPs is known to be not enough. Hydrodynamic cavitation is the process of vaporization, bubble generation and bubble implosion which occurs in a flowing liquid as a result of decrease and subsequent increase in pressure. Hydrodynamic cavitation generates shock pressure of a few tens MPa due to bubble collapse like the cavitation generated by Ultrasonics. It is well known that the cavitation can erode the metal surface. The idea of the current study is that such energetic cavitation bubble collapses could help to remove the crud from the fuel assembly. Therefore, the current study first investigates effects of hydrodynamic cavitation occurred from a single hole orifice fundamentally

Effects of Hydrodynamic Cavitation of a Restriction Orifice on Crud-like Deposits

Energy Technology Data Exchange (ETDEWEB)

Kim, Seong Man; Lee, Seung Won; Park, Sung Dae; Kang, Sarah; Seo, Han; Bang, In Cheol [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

2011-10-15

Axial Offset Anomaly (AOA) referring to an unexpected neutron flux depression is also known as Crud Induced Power Shift (CIPS). Fuel assemblies removed from an AOA core has shown a thick porous deposition layer of crud on fuel clad surface. The deposition layer was induced by precipitation reactions of both boron species and crud during sub-cooled nucleate boiling. Therefore, to resolve the AOA issues, a fuel cleaning technology using ultrasonic cavitation has been developed by EPRI and applied to the domestic NPPs by KNF. However, the performance of crud removal during maintenance of NPPs is known to be not enough. Hydrodynamic cavitation is the process of vaporization, bubble generation and bubble implosion which occurs in a flowing liquid as a result of decrease and subsequent increase in pressure. Hydrodynamic cavitation generates shock pressure of a few tens MPa due to bubble collapse like the cavitation generated by Ultrasonics. It is well known that the cavitation can erode the metal surface. The idea of the current study is that such energetic cavitation bubble collapses could help to remove the crud from the fuel assembly. Therefore, the current study first investigates effects of hydrodynamic cavitation occurred from a single hole orifice fundamentally

Hydrodynamic cavitation in Stokes flow of anisotropic fluids

Science.gov (United States)

Stieger, Tillmann; Agha, Hakam; Schoen, Martin; Mazza, Marco G.; Sengupta, Anupam

2017-05-01

Cavitation, the nucleation of vapour in liquids, is ubiquitous in fluid dynamics, and is often implicated in a myriad of industrial and biomedical applications. Although extensively studied in isotropic liquids, corresponding investigations in anisotropic liquids are largely lacking. Here, by combining liquid crystal microfluidic experiments, nonequilibrium molecular dynamics simulations and theoretical arguments, we report flow-induced cavitation in an anisotropic fluid. The cavitation domain nucleates due to sudden pressure drop upon flow past a cylindrical obstacle within a microchannel. For an anisotropic fluid, the inception and growth of the cavitation domain ensued in the Stokes regime, while no cavitation was observed in isotropic liquids flowing under similar hydrodynamic parameters. Using simulations we identify a critical value of the Reynolds number for cavitation inception that scales inversely with the order parameter of the fluid. Strikingly, the critical Reynolds number for anisotropic fluids can be 50% lower than that of isotropic fluids.

Oxidation of alkylarenes to the corresponding acids using aqueous potassium permanganate by hydrodynamic cavitation.

Science.gov (United States)

Ambulgekar, G V; Samant, S D; Pandit, A B

2004-05-01

Oxidation of toluene using aqueous potassium permanganate was studied under heterogeneous condition in the presence of hydrodynamic cavitation and compared with the results of the reaction under acoustic cavitation. Various parameters, such as quantity of potassium permanganate, toluene to aqueous phase ratio, reaction time and cavitation parameters such as orifice plate, and pump discharge pressure were optimized. The reaction was found to be considerably accelerated at ambient temperature in the presence of cavitation. On comparison, it was found that when 1 kJ of energy was passed to the reaction mixture in the case of acoustic cavitation, the product obtained was 4.63 x 10(-6) mol, whereas when 1 kJ of energy was passed to the reaction mixture in the case of hydrodynamic cavitation the product obtained was 2.70 x 10(-5) mol. Hence, about six times more product would be obtained in the case of hydrodynamic cavitation than in the case of acoustic cavitation at same energy dissipation. It has been observed that further optimization is possible.

Numerical and experimental study of a hydrodynamic cavitation tube

Science.gov (United States)

Hu, H.; Finch, J. A.; Zhou, Z.; Xu, Z.

1998-08-01

A numerical analysis of hydrodynamics in a cavitation tube used for activating fine particle flotation is described. Using numerical procedures developed for solving the turbulent k-ɛ model with boundary fitted coordinates, the stream function, vorticity, velocity, and pressure distributions in a cavitation tube were calculated. The calculated pressure distribution was found to be in excellent agreement with experimental results. The requirement of a pressure drop below approximately 10 m water for cavitation to occur was observed experimentally and confirmed by the model. The use of the numerical procedures for cavitation tube design is discussed briefly.

Hydrodynamic study of the rotating cylinder mixer of a laboratory centrifugal extractor

International Nuclear Information System (INIS)

Philipponeau, Yannick.

1979-08-01

As part of a research programme on solvent extraction kinetics the Fontenay-aux-Roses Nuclear Research Centre has undertaken to build a new centrifugal extractor prototype. The work was centred on a hydrodynamic study of the rotating cylinder mixer of the extractor, using a test apparatus specially designed for this purpose. This apparatus was used to determine the flow conditions of a liquid alone in the annular space of the mixer as a function of the working specifications. The existence of several types of flow was established. The stability region of which was determined as a function of different parameters for a number of liquid-liquid systems. The experiments showed in addition that two kinds of dispersion can be obtained, differing by the nature of the continuous phase. This was determined for various parameters of certain liquid-liquid systems. From this research the hydrodynamic behavior of the CEA centrifugal extractor prototype mixer is thus known [fr

Experimental investigation of hydrodynamic cavitation through orifices of different geometries

Science.gov (United States)

Rudolf, Pavel; Kubina, Dávid; Hudec, Martin; Kozák, Jiří; Maršálek, Blahoslav; Maršálková, Eliška; Pochylý, František

Hydrodynamic cavitation in single and multihole orifices was experimentally investigated to assess their hydraulic characteristics: loss coefficients, inception cavitation number, cavitation number for transition to supercavitation. Significant difference for singlehole and multihole orifices was observed in terms of the measured loss coefficient. It is significantly more effective to use multihole orifices, where energy dissipation is much lower.It was found that using scaling factor given by ratio of orifice thickness suggests linear behaviour of both loss coefficient and inception cavitation number. Orifices seem to be convenient choice as flow constriction devices inducing cavitation due to their simplicity.

Experimental investigation of hydrodynamic cavitation through orifices of different geometries

Directory of Open Access Journals (Sweden)

Rudolf Pavel

2017-01-01

Full Text Available Hydrodynamic cavitation in single and multihole orifices was experimentally investigated to assess their hydraulic characteristics: loss coefficients, inception cavitation number, cavitation number for transition to supercavitation. Significant difference for singlehole and multihole orifices was observed in terms of the measured loss coefficient. It is significantly more effective to use multihole orifices, where energy dissipation is much lower.It was found that using scaling factor given by ratio of orifice thickness suggests linear behaviour of both loss coefficient and inception cavitation number. Orifices seem to be convenient choice as flow constriction devices inducing cavitation due to their simplicity.

Enhanced decolorization of methyl orange using zero-valent copper nanoparticles under assistance of hydrodynamic cavitation.

Science.gov (United States)

Li, Pan; Song, Yuan; Wang, Shuai; Tao, Zheng; Yu, Shuili; Liu, Yanan

2015-01-01

The rate of reduction reactions of zero-valent metal nanoparticles is restricted by their agglomeration. Hydrodynamic cavitation was used to overcome the disadvantage in this study. Experiments for decolorization of methyl orange azo dye by zero-valent copper nanoparticles were carried out in aqueous solution with and without hydrodynamic cavitation. The results showed that hydrodynamic cavitation greatly accelerated the decolorization rate of methyl orange. The size of nanoparticles was decreased after hydrodynamic cavitation treatment. The effects of important operating parameters such as discharge pressure, initial solution pH, and copper nanoparticle concentration on the degradation rates were studied. It was observed that there was an optimum discharge pressure to get best decolorization performance. Lower solution pH were favorable for the decolorization. The pseudo-first-order kinetic constant for the degradation of methyl orange increased linearly with the copper dose. UV-vis spectroscopic and Fourier transform infrared (FT-IR) analyses confirmed that many degradation intermediates were formed. The results indicated hydroxyl radicals played a key role in the decolorization process. Therefore, the enhancement of decolorization by hydrodynamic cavitation could due to the deagglomeration of nanoparticles as well as the oxidation by the in situ generated hydroxyl radicals. These findings greatly increase the potential of the Cu(0)/hydrodynamic cavitation technique for use in the field of treatment of wastewater containing hazardous materials. Copyright © 2014 Elsevier B.V. All rights reserved.

Observation of chemiluminescence induced by hydrodynamic cavitation in microchannels.

Science.gov (United States)

Podbevsek, D; Colombet, D; Ledoux, G; Ayela, F

2018-05-01

We have performed hydrodynamic cavitation experiments with an aqueous luminol solution as the working fluid. Light emission, together with the high frequency noise which characterizes cavitation, was emitted by the two-phase flow, whereas no light emission from luminol was recorded in the single phase liquid flow. Light emission occurs downstream transparent microdiaphragms. The maximum level of the recorded signal was around 180 photons per second with flow rates of 380 µl/s, that corresponds to a real order of magnitude of the chemiluminescence of 75,000 photons per second. The yield of emitted photons increases linearly with the pressure drop, which is proportional to the square of the total flow rate. Chemiluminescence of luminol is a direct and a quantitative demonstration of the presence of OH hydroxyl radicals created by hydrodynamic cavitation. The presented method could be a key to optimize channel geometry for processes where radical production is essential. Copyright © 2018 Elsevier B.V. All rights reserved.

Degradation of diclofenac sodium using combined processes based on hydrodynamic cavitation and heterogeneous photocatalysis.

Science.gov (United States)

Bagal, Manisha V; Gogate, Parag R

2014-05-01

Diclofenac sodium, a widely detected pharmaceutical drug in wastewater samples, has been selected as a model pollutant for degradation using novel combined approach of hydrodynamic cavitation and heterogeneous photocatalysis. A slit venturi has been used as cavitating device in the hydrodynamic cavitation reactor. The effect of various operating parameters such as inlet fluid pressure (2-4 bar) and initial pH of the solution (4-7.5) on the extent of degradation have been studied. The maximum extent of degradation of diclofenac sodium was obtained at inlet fluid pressure of 3 bar and initial pH as 4 using hydrodynamic cavitation alone. The loadings of TiO2 and H2O2 have been optimised to maximise the extent of degradation of diclofenac sodium. Kinetic study revealed that the degradation of diclofenac sodium fitted first order kinetics over the selected range of operating protocols. It has been observed that combination of hydrodynamic cavitation with UV, UV/TiO2 and UV/TiO2/H2O2 results in enhanced extents of degradation as compared to the individual schemes. The maximum extent of degradation as 95% with 76% reduction in TOC has been observed using hydrodynamic cavitation in conjunction with UV/TiO2/H2O2 under the optimised operating conditions. The diclofenac sodium degradation byproducts have been identified using LC/MS analysis. Copyright © 2013 Elsevier B.V. All rights reserved.

Hydrodynamic Cavitation through “Labs on a Chip”: From Fundamentals to Applications

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Ayela Frederic

2017-07-01

Full Text Available Monitoring hydrodynamic cavitation of liquids through “labs on a chip” (i.e. microchannels with a shrinkage, such as microdiaphragms or microventuris is an improvement in experimental approaches devoted to study the mechanisms involved in these multiphase flows. The small sizes of the reactors do not require big substructures. Flow rates of around 1 L/h make possible the characterisation of rare, toxic or expensive pure fluids or mixtures. Moreover, because of that microfluidic approach, an unique inception of the cavitation from a laminar flow regime is also possible, that provides precious databases for simulation or modelisation. Lastly, “labs on a chip” are an extremely versatile solution to perform novel experiments, as they are embeddable in tools basically designed to proceed with small samples (confocal microscopy, spectroscopy. We present here a summary of the former experiments performed by our team, concerning the fundamental aspects of hydrodynamic cavitation in a microchannel. We have recorded, with thermosensitive nanoparticles dispersed in water, the thermal signature of the growth and collapse of bubbles. We were also able to monitor the cavitation flow regime from a laminar single liquid phase. We are currently involved in applicative studies of hydrodynamic cavitation in microchannels, and preliminary results concerning liquid phase exfoliation of graphene will be also presented.

Hydrodynamic cavitation: from theory towards a new experimental approach

Science.gov (United States)

Lucia, Umberto; Gervino, Gianpiero

2009-09-01

Hydrodynamic cavitation is analysed by a global thermodynamics principle following an approach based on the maximum irreversible entropy variation that has already given promising results for open systems and has been successfully applied in specific engineering problems. In this paper we present a new phenomenological method to evaluate the conditions inducing cavitation. We think this method could be useful in the design of turbo-machineries and related technologies: it represents both an original physical approach to cavitation and an economical saving in planning because the theoretical analysis could allow engineers to reduce the experimental tests and the costs of the design process.

Study on transient hydrodynamic performance and cavitation characteristic of high-speed mixed-flow pump

International Nuclear Information System (INIS)

Chen, T; Liu, Y L; Sun, Y B; Wang, L Q; Wu, D Z

2013-01-01

In order to analyse the hydrodynamic performance and cavitation characteristic of a high-speed mixed-flow pump during transient operations, experimental studies were carried out. The transient hydrodynamic performance and cavitation characteristics of the mixed-flow pump with guide vane during start-up operation processes were tested on the pump performance test-bed. Performance tests of the pump were carried out under various inlet pressures and speed-changing operations. The real-time instantaneous external characteristics such as rotational speed, hydraulic head, flow rate, suction pressure and discharge pressure of the pump were measured. Based on the experimental results, the effect of fluid acceleration on the hydrodynamic performances and cavitation characteristics of the mixed-flow pump were analysed and evaluated

Killing rate of colony count by hydrodynamic cavitation due to square multi-orifice plates

Science.gov (United States)

Dong, Zhiyong; Zhao, Wenqian

2018-02-01

Currently,in water supply engineering, the conventional technique of disinfection by chlorination is employed to kill pathogenic microorganisms in raw water. However, chlorine reacts with organic compounds in water and generates disinfection byproducts (DBPs), such as trihalomethanes (THMs), haloacetic acids (HAAs) etc. These byproducts are of carcinogenic, teratogenic and mutagenic effects, which seriously threaten human health. Hydrodynamic cavitation is a novel technique of drinking water disinfection without DBPs. Effects of orifice size, orifice number and orifice layout of multi-orifice plate, cavitation number, cavitation time and orifice velocity on killing pathogenic microorganisms by cavitation were investigated experimentally in a self-developed square multi-orifice plate-type hydrodynamic cavitation device. The experimental results showed that cavitation effects increased with decrease in orifice size and increase in orifice number, cavitation time and orifice velocity. Along with lowering in cavitation number, there was an increase in Reynolds shear stress,thus enhancing the killing rate of pathogenic microorganism in raw water. In addition, the killing rate by staggered orifice layout was greater than that by checkerboard-type orifice layout.

Hydrodynamic cavitation in microsystems. I. Experiments with deionized water and nanofluids

Science.gov (United States)

Medrano, M.; Zermatten, P. J.; Pellone, C.; Franc, J. P.; Ayela, F.

2011-12-01

An experimental study of hydrodynamic cavitation downstream microdiaphragms and microventuris is presented. Deionized water and nanofluids have been characterized within silicon-Pyrex micromachined devices with hydraulic diameters ranging from 51 μm to 104 μm. The input pressure could reach up to 10 bars, and the flow rate was below 1 liter per hour. The output pressure of the devices was fixed at values ranging from 0.3 bar to 2 bars, so that it was possible to study the evolution of the cavitation number as a function of the Reynolds number in the orifice of the diaphragms or in the throat of the venturis. A delay on the onset of cavitation has been recorded for all the devices when they are fed with deionized water, because of the metastability of the liquid and because of the lack of roughness of the walls. For the first time, hydrodynamic cavitation of nanofluids (nanoparticles dispersed into the liquid) has been considered. The presence of nano-aggregates in the liquid does not exhibit any noticeable effect on the cavitation threshold through the venturis. However, such a presence has a strong influence on the cavitation onset in microdiaphragms: above a critical volume solid concentration of ≈10-5, the metastability is broken and the nanofluids behave as tap water filled up with large nuclei. These microdevices, where a low amount of fluid is required to reach cavitating flows, appear to be useful tools in order to study cavitating phenomena in localized area with specific fluids.

Intensification of esterification of acids for synthesis of biodiesel using acoustic and hydrodynamic cavitation.

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Kelkar, Mandar A; Gogate, Parag R; Pandit, Aniruddha B

2008-03-01

Cavitation results in conditions of turbulence and liquid circulation in the reactor which can aid in eliminating mass transfer resistances. The present work illustrates the use of cavitation for intensification of biodiesel synthesis (esterification) reaction, which is mass transfer limited reaction considering the immiscible nature of the reactants, i.e., fatty acids and alcohol. Esterification of fatty acid (FA) odour cut (C(8)-C(10)) with methanol in the presence of concentrated H(2)SO(4) as a catalyst has been studied in hydrodynamic cavitation reactor as well as in the sonochemical reactor. The different reaction operating parameters such as molar ratio of acid to alcohol, catalyst quantity have been optimized under acoustic as well as hydrodynamic cavitating conditions in addition to the optimization of the geometry of the orifice plate in the case of hydrodynamic cavitation reactors. Few experiments have also been carried out with other acid (lower and higher)/methanol combination viz. caprylic acid and capric acids with methanol with an aim of investigating the efficacy of cavitation for giving the desired yields and also to quantify the degree of process intensification that can be achieved using the same. It has been observed that ambient operating conditions of temperature and pressure and reaction times of 90% conversion (mol%). This clearly establishes the efficacy of cavitation as an excellent way to achieve process intensification of the biodiesel synthesis process.

Study on hydrodynamics and mass transfer of the critically safe multistage mixer-settler

International Nuclear Information System (INIS)

Zhang Weibo; Jiao Rongzhou; Liu Bingren

1992-08-01

The study on structure of critically safe multistage mixer-settler for the extraction process of high enriched uranium and plutonium has been completed. The mixer-settler has simple structure, good critical safety, flexibility in operation (O/A from 0.5 to 5) and high extraction efficiency (E x > 90%). These performances have been proved in the hydrodynamics and mass transfer experiments at a three stages cascade mixer-settler. Based on the others experience, a trapezoidal impeller combined with half-open turbine is developed which has stronger pumping and well mixing function at low rotating speed. The optimal rotating speed is 250 to 280 r/min obtained by experiments

Application of salicylic acid dosimetry to evaluate hydrodynamic cavitation as an advanced oxidation process.

Science.gov (United States)

Arrojo, S; Nerín, C; Benito, Y

2007-03-01

The generation of OH* radicals inside hydrodynamic cavitation bubbles was monitored using a salicylic acid dosimeter. The reaction of this scavenger with OH* produces 2,5-dihydroxybenzoic acid (2,5-DHB) and, to a lesser degree, 2,3-DHB. The former, is a specific reaction product that can be determined with a very high sensitivity using HPLC-IF. This method has been applied to study the influence of the flow-rate and the solution pH for a given cavitation chamber geometry. The salicylic dosimetry has proven especially suitable for the characteristic time scales of hydrodynamic cavitation (higher than those of ultrasonic cavitation), which usually gives rise to recombination of radicals before they can reach the liquid-phase. Working at low pH the hydrophobic salicylic acid migrates to the gas-liquid interface and reacts with the OH* radicals, increasing the trapping efficiency of the dosimeter. Hydrodynamic cavitation works as a very low frequency sonochemical reactor, and therefore its potential as an Advanced Oxidation Process might be limited to reactions at the gas-liquid interface and inner bubble (i.e. with volatiles and/or hydrophobic substances).

Motion-sensitized SPRITE measurements of hydrodynamic cavitation in fast pipe flow.

Science.gov (United States)

Adair, Alexander; Mastikhin, Igor V; Newling, Benedict

2018-06-01

The pressure variations experienced by a liquid flowing through a pipe constriction can, in some cases, result in the formation of a bubble cloud (i.e., hydrodynamic cavitation). Due to the nature of the bubble cloud, it is ideally measured through the use of non-optical and non-invasive techniques; therefore, it is well-suited for study by magnetic resonance imaging. This paper demonstrates the use of Conical SPRITE (a 3D, centric-scan, pure phase-encoding pulse sequence) to acquire time-averaged void fraction and velocity information about hydrodynamic cavitation for water flowing through a pipe constriction. Copyright © 2018 Elsevier Inc. All rights reserved.

Study of physical and biological factors involved in the disruption of E. coli by hydrodynamic cavitation.

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Balasundaram, B; Harrison, S T L

2006-01-01

Hydrodynamic cavitation results in flow restriction in a flow system causing rapid pressure fluctuations and significant fluid forces. These can be harnessed to mediate microbial cell damage. Hydrodynamic cavitation was studied for the partial disruption of E. coli and selective release of specific proteins relative to the total soluble protein. The effects of the cavitation number, the number of passes, and the specific growth rate of E. coli on the release of periplasmic and cytoplasmic proteins were studied. At the optimum cavitation number of 0.17 for this experimental configuration, 48% of the total soluble protein, 88% of acid phosphatase, and 67% of beta-galactosidase were released by hydrodynamic cavitation in comparison with the maximum release attained using multiple passes through the French Press. The higher release of the acid phosphatase over the total soluble protein suggested preferred release of periplasmic compounds. This was supported by SDS-PAGE analysis. The absence of micronization of cell material resulting in the potential for ease of solid-liquid separation downstream of the cell disruption operation was confirmed by TEM microscopy. E. coli cells cultivated at a higher specific growth rate (0.36 h(-1)) were more easily disrupted than slower grown cells (0.11 h(-1)). The specific activity of the enzyme of interest released by hydrodynamic cavitation, defined as the units of enzyme in solution per milligram of total soluble protein, was greater than that obtained on release by the French Press, high-pressure homogenization, osmotic shock, and EDTA treatment. The selectivity offered indicates the potential of enzyme release by hydrodynamic cavitation to ease the purification in the subsequent downstream processing.

Degradation of BTEX in aqueous solution by hydrodynamic cavitation

Energy Technology Data Exchange (ETDEWEB)

Braeutigam, P.; Wu, Z.-L.; Stark, A.; Ondruschka, B. [Institute for Technical Chemistry and Environmental Chemistry, Friedrich Schiller University, Jena (Germany)

2009-05-15

A self-made low-pressure device (up to 100 psi) for hydrodynamic cavitation was tested with the reaction of BTEX (benzene, toluene, ethylbenzene, and xylenes) in water. Experimental parameters, such as inlet pressure, solution temperature, and concentration of the chosen substrates, as well as the effect of different restrictions were investigated. The energy efficiency of the process was measured in comparison to two acoustic cavitation systems (24 and 850 kHz). The products of the BTEX degradation were identified and a pyrolytic degradation pathway is concluded. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Hydrodynamic cavitation in micro channels with channel sizes of 100 and 750 micrometers

NARCIS (Netherlands)

Rooze, J.; Andre, M.; Gulik, van der G.J.S.; Fernandez-Rivas, D.; Gardeniers, J.G.E.; Rebrov, E.; Schouten, J.C.; Keurentjes, J.T.F.

2012-01-01

Decreasing the constriction size and residence time in hydrodynamic cavitation is predicted to give increased hot spot temperatures at bubble collapse and increased radical formation rate. Cavitation in a 100 × 100 µm2 rectangular micro channel and in a circular 750 µm diameter milli channel has

Disruption of Brewers' yeast by hydrodynamic cavitation: Process variables and their influence on selective release.

Science.gov (United States)

Balasundaram, B; Harrison, S T L

2006-06-05

Intracellular products, not secreted from the microbial cell, are released by breaking the cell envelope consisting of cytoplasmic membrane and an outer cell wall. Hydrodynamic cavitation has been reported to cause microbial cell disruption. By manipulating the operating variables involved, a wide range of intensity of cavitation can be achieved resulting in a varying extent of disruption. The effect of the process variables including cavitation number, initial cell concentration of the suspension and the number of passes across the cavitation zone on the release of enzymes from various locations of the Brewers' yeast was studied. The release profile of the enzymes studied include alpha-glucosidase (periplasmic), invertase (cell wall bound), alcohol dehydrogenase (ADH; cytoplasmic) and glucose-6-phosphate dehydrogenase (G6PDH; cytoplasmic). An optimum cavitation number Cv of 0.13 for maximum disruption was observed across the range Cv 0.09-0.99. The optimum cell concentration was found to be 0.5% (w/v, wet wt) when varying over the range 0.1%-5%. The sustained effect of cavitation on the yeast cell wall when re-circulating the suspension across the cavitation zone was found to release the cell wall bound enzyme invertase (86%) to a greater extent than the enzymes from other locations of the cell (e.g. periplasmic alpha-glucosidase at 17%). Localised damage to the cell wall could be observed using transmission electron microscopy (TEM) of cells subjected to less intense cavitation conditions. Absence of the release of cytoplasmic enzymes to a significant extent, absence of micronisation as observed by TEM and presence of a lower number of proteins bands in the culture supernatant on SDS-PAGE analysis following hydrodynamic cavitation compared to disruption by high-pressure homogenisation confirmed the selective release offered by hydrodynamic cavitation. Copyright 2006 Wiley Periodicals, Inc.

Hydrodynamic cavitation in micro channels with channel sizes of 100 and 750 micrometers

NARCIS (Netherlands)

Rooze, J.; André, M.; van der Gulik, G-J.S.; Fernandez Rivas, David; Gardeniers, Johannes G.E.; Rebrov, E.V.; Schouten, J.C.; Keurentjes, J.T.F.

2012-01-01

Decreasing the constriction size and residence time in hydrodynamic cavitation is predicted to give increased hot spot temperatures at bubble collapse and increased radical formation rate. Cavitation in a 100 × 100 μm2 rectangular micro channel and in a circular 750 μm diameter milli channel has

A review and assessment of hydrodynamic cavitation as a technology for the future.

Science.gov (United States)

Gogate, Parag R; Pandit, Aniruddha B

2005-01-01

In the present work, the current status of the hydrodynamic cavitation reactors has been reviewed discussing the bubble dynamics analysis, optimum design considerations, design correlations for cavitational intensity (in terms of collapse pressure)/cavitational yield and different successful chemical synthesis applications clearly illustrating the utility of these types of reactors. The theoretical discussion based on the modeling of the bubble dynamics equations aims at understanding the design information related to the dependency of the cavitational intensity on the operating parameters and recommendations have been made for the choice of the optimized conditions of operating parameters. The design information based on the theoretical analysis has also been supported with some experimental illustrations concentrating on the chemical synthesis applications. Assessment of the hydrodynamic cavitation reactors and comparison with the sonochemical reactors has been done by citing the different industrially important reactions (oxidation of toluene, o-xylene, m-xylene, p-xylene, mesitylene, o-nitrotoluene, p-nitrotoluene, m-nitrotoluene, o-chlorotoluene and p-chlorotoulene, and trans-esterification reaction i.e., synthesis of bio-diesel). Some recommendations have also been made for the future work to be carried out as well as the choice of the operating conditions for realizing the dream of industrial scale applications of the cavitational reactors.

Effective method of treatment of effluents from production of bitumens under basic pH conditions using hydrodynamic cavitation aided by external oxidants.

Science.gov (United States)

Boczkaj, Grzegorz; Gągol, Michał; Klein, Marek; Przyjazny, Andrzej

2018-01-01

Utilization of cavitation in advanced oxidation processes (AOPs) is a promising trend in research on treatment of industrial effluents. The paper presents the results of investigations on the use of hydrodynamic cavitation aided by additional oxidation processes (O 3 /H 2 O 2 /Peroxone) to reduce the total pollution load in the effluent from the production of bitumens. A detailed analysis of changes in content of volatile organic compounds (VOCs) for all processes studied was also performed. The studies revealed that the most effective treatment process involves hydrodynamic cavitation aided by ozonation (40% COD reduction and 50% BOD reduction). The other processes investigated (hydrodynamic cavitation+H 2 O 2 , hydrodynamic cavitation+Peroxone and hydrodynamic cavitation alone) ensure reduction of COD by 20, 25 and 13% and reduction of BOD by 49, 32 and 18%, respectively. The results of this research revealed that most of the VOCs studied are effectively degraded. The formation of byproducts is one of the aspects that must be considered in evaluation of the AOPs studied. This work confirmed that furfural is one of the byproducts whose concentration increased during treatment by hydrodynamic cavitation alone as well as hydrodynamic cavitation aided by H 2 O 2 as an external oxidant and it should be controlled during treatment processes. Copyright © 2017 Elsevier B.V. All rights reserved.

A simple process to achieve microchannels geometries able to produce hydrodynamic cavitation

Science.gov (United States)

Qiu, X.; Cherief, W.; Colombet, D.; Ayela, F.

2017-04-01

We present a simple process to perform microchannels in which cavitating two phase flows are easily producible. Up to now, hydrodynamic cavitation ‘on a chip’ was reached with small flow rates inside microchannels whose micromachining had involved a deep reactive ion etching (D-RIE). The process we present here does not require a D-RIE reactor, as it is only funded on a wet etching of silicon. It leads to a so-called microstep profile, and large cavitating flow rates become possible together with moderate pressure drops.

A simple process to achieve microchannels geometries able to produce hydrodynamic cavitation

International Nuclear Information System (INIS)

Qiu, X; Cherief, W; Colombet, D; Ayela, F

2017-01-01

We present a simple process to perform microchannels in which cavitating two phase flows are easily producible. Up to now, hydrodynamic cavitation ‘on a chip’ was reached with small flow rates inside microchannels whose micromachining had involved a deep reactive ion etching (D-RIE). The process we present here does not require a D-RIE reactor, as it is only funded on a wet etching of silicon. It leads to a so-called microstep profile, and large cavitating flow rates become possible together with moderate pressure drops. (technical note)

Effect of hydrodynamic cavitation in the tissue erosion by pulsed high-intensity focused ultrasound (pHIFU)

Science.gov (United States)

Zhou, Yufeng; Gao, Xiaobin Wilson

2016-09-01

High-intensity focused ultrasound (HIFU) is emerging as an effective therapeutic modality in clinics. Besides the thermal ablation, tissue disintegration is also possible because of the interaction between the distorted HIFU bursts and either bubble cloud or boiling bubble. Hydrodynamic cavitation is another type of cavitation and has been employed widely in industry, but its role in mechanical erosion to tissue is not clearly known. In this study, the bubble dynamics immediately after the termination of HIFU exposure in the transparent gel phantom was captured by high-speed photography, from which the bubble displacement towards the transducer and the changes of bubble size was quantitatively determined. The characteristics of hydrodynamic cavitation due to the release of the acoustic radiation force and relaxation of compressed surrounding medium were found to associate with the number of pulses delivered and HIFU parameters (i.e. pulse duration and pulse repetition frequency). Because of the initial big bubble (~1 mm), large bubble expansion (up to 1.76 folds), and quick bubble motion (up to ~1 m s-1) hydrodynamic cavitation is significant after HIFU exposure and may lead to mechanical erosion. The shielding effect of residual tiny bubbles would reduce the acoustic energy delivered to the pre-existing bubble at the focus and, subsequently, the hydrodynamic cavitation effect. Tadpole shape of mechanical erosion in ex vivo porcine kidney samples was similar to the contour of bubble dynamics in the gel. Liquefied tissue was observed to emit towards the transducer through the punctured tissue after HIFU exposure in the sonography. In summary, the release of HIFU exposure-induced hydrodynamic cavitation produces significant bubble expansion and motion, which may be another important mechanism of tissue erosion. Understanding its mechanism and optimizing the outcome would broaden and enhance HIFU applications.

Effect of hydrodynamic cavitation in the tissue erosion by pulsed high-intensity focused ultrasound (pHIFU).

Science.gov (United States)

Zhou, Yufeng; Gao, Xiaobin Wilson

2016-09-21

High-intensity focused ultrasound (HIFU) is emerging as an effective therapeutic modality in clinics. Besides the thermal ablation, tissue disintegration is also possible because of the interaction between the distorted HIFU bursts and either bubble cloud or boiling bubble. Hydrodynamic cavitation is another type of cavitation and has been employed widely in industry, but its role in mechanical erosion to tissue is not clearly known. In this study, the bubble dynamics immediately after the termination of HIFU exposure in the transparent gel phantom was captured by high-speed photography, from which the bubble displacement towards the transducer and the changes of bubble size was quantitatively determined. The characteristics of hydrodynamic cavitation due to the release of the acoustic radiation force and relaxation of compressed surrounding medium were found to associate with the number of pulses delivered and HIFU parameters (i.e. pulse duration and pulse repetition frequency). Because of the initial big bubble (~1 mm), large bubble expansion (up to 1.76 folds), and quick bubble motion (up to ~1 m s -1 ) hydrodynamic cavitation is significant after HIFU exposure and may lead to mechanical erosion. The shielding effect of residual tiny bubbles would reduce the acoustic energy delivered to the pre-existing bubble at the focus and, subsequently, the hydrodynamic cavitation effect. Tadpole shape of mechanical erosion in ex vivo porcine kidney samples was similar to the contour of bubble dynamics in the gel. Liquefied tissue was observed to emit towards the transducer through the punctured tissue after HIFU exposure in the sonography. In summary, the release of HIFU exposure-induced hydrodynamic cavitation produces significant bubble expansion and motion, which may be another important mechanism of tissue erosion. Understanding its mechanism and optimizing the outcome would broaden and enhance HIFU applications.

Degradation of imidacloprid using combined advanced oxidation processes based on hydrodynamic cavitation.

Science.gov (United States)

Patil, Pankaj N; Bote, Sayli D; Gogate, Parag R

2014-09-01

The harmful effects of wastewaters containing pesticides or insecticides on human and aquatic life impart the need of effectively treating the wastewater streams containing these contaminants. In the present work, hydrodynamic cavitation reactors have been applied for the degradation of imidacloprid with process intensification studies based on different additives and combination with other similar processes. Effect of different operating parameters viz. concentration (20-60 ppm), pressure (1-8 bar), temperature (34 °C, 39 °C and 42 °C) and initial pH (2.5-8.3) has been investigated initially using orifice plate as cavitating device. It has been observed that 23.85% degradation of imidacloprid is obtained at optimized set of operating parameters. The efficacy of different process intensifying approaches based on the use of hydrogen peroxide (20-80 ppm), Fenton's reagent (H2O2:FeSO4 ratio as 1:1, 1:2, 2:1, 2:2, 4:1 and 4:2), advanced Fenton process (H2O2:Iron Powder ratio as 1:1, 2:1 and 4:1) and combination of Na2S2O8 and FeSO4 (FeSO4:Na2S2O8 ratio as 1:1, 1:2, 1:3 and 1:4) on the extent of degradation has been investigated. It was observed that near complete degradation of imidacloprid was achieved in all the cases at optimized values of process intensifying parameters. The time required for complete degradation of imidacloprid for approach based on hydrogen peroxide was 120 min where as for the Fenton and advance Fenton process, the required time was only 60 min. To check the effectiveness of hydrodynamic cavitation with different cavitating devices, few experiments were also performed with the help of slit venturi as a cavitating device at already optimized values of parameters. The present work has conclusively established that combined processes based on hydrodynamic cavitation can be effectively used for complete degradation of imidacloprid. Copyright © 2014 Elsevier B.V. All rights reserved.

Preparation of biodiesel with the help of ultrasonic and hydrodynamic cavitation.

Science.gov (United States)

Ji, Jianbing; Wang, Jianli; Li, Yongchao; Yu, Yunliang; Xu, Zhichao

2006-12-22

An alkali-catalyzed biodiesel production method with power ultrasonic (19.7 kHz) has been developed that allows a short reaction time and high yield because of emulsification and cavitation of the liquid-liquid immiscible system. Orthogonality experiments were employed to evaluate the effects of synthesis parameters. Furthermore, hydrodynamic cavitation was used for biodiesel production in comparison to ultrasonic method. Both methods were proved to be efficient, and time and energy saving for the preparation of biodiesel by transesterification of soybean oil.

Removal of blue-green algae using the hybrid method of hydrodynamic cavitation and ozonation.

Science.gov (United States)

Wu, Zhilin; Shen, Haifeng; Ondruschka, Bernd; Zhang, Yongchun; Wang, Weimin; Bremner, David H

2012-10-15

A suspension of Microcystis aeruginosa (30 μg L(-1)chlorophyll a) was circulated in a hydrodynamic cavitation device and ozone was introduced at the suction side of the pump. The removal of algae over 10 min using hydrodynamic cavitation alone and ozone alone is less than 15% and 35%, respectively. The destruction of algae rises significantly from 24% in the absence of the orifice to 91% with the optimized orifice on 5 min of processing using hydrodynamic cavitation along with ozone (HC/O(3)) and the utilization of ozone increases from 32% to 61%. Interestingly, the suction process is more effective than the extrusion method (positive pressure) and the optimal bulk temperature for algal elimination was found to be 20 °C. Increasing the input concentration of ozone is favorable for the removal of algae but leads to a greater loss of ozone and a decrease in the utilization of ozone. Under the optimal conditions, the algal cells and chlorophyll a are completely destroyed in 10 min by use of the hybrid method. Copyright © 2012 Elsevier B.V. All rights reserved.

Shear-induced hydrodynamic cavitation as a tool for pharmaceutical micropollutants removal from urban wastewater.

Science.gov (United States)

Zupanc, Mojca; Kosjek, Tina; Petkovšek, Martin; Dular, Matevž; Kompare, Boris; Širok, Brane; Stražar, Marjeta; Heath, Ester

2014-05-01

In this study, the removal of clofibric acid, ibuprofen, naproxen, ketoprofen, carbamazepine and diclofenac residues from wastewater, using a novel shear-induced cavitation generator has been systematically studied. The effects of temperature, cavitation time and H2O2 dose on removal efficiency were investigated. Optimisation (50°C; 15 min; 340 mg L(-1) of added H2O2) resulted in removal efficiencies of 47-86% in spiked deionised water samples. Treatment of actual wastewater effluents revealed that although matrix composition reduces removal efficiency, this effect can be compensated for by increasing H2O2 dose (3.4 g L(-1)) and prolonging cavitation time (30 min). Hydrodynamic cavitation has also been investigated as either a pre- or a post-treatment step to biological treatment. The results revealed a higher overall removal efficiency of recalcitrant diclofenac and carbamazepine, when hydrodynamic cavitation was used prior to as compared to post biological treatment i.e., 54% and 67% as compared to 39% and 56%, respectively. This is an important finding since diclofenac is considered as a priority substance to be included in the EU Water Framework Directive. Copyright © 2013 Elsevier B.V. All rights reserved.

Analysis on transient hydrodynamic characteristics of cavitation process for reactor coolant pump

International Nuclear Information System (INIS)

Wang Xiuli; Wang Peng; Yuan Shouqi; Zhu Rongsheng; Fu Qiang

2014-01-01

The reactor coolant pump hydrodynamic characteristics at different cavitation conditions were studied by using flow field analysis software ANSYS CFX, and the corresponding data were processed and analyzed by using Morlet wavelet transform and fast Fourier transform. The results show that gas content presents the law of exponential function with the pressure reduction or time increase. In the cavitation primary condition, the pulsation frequency of head for the reactor coolant pump is mainly low frequency, and the main frequency of pressure pulsation is still rotation frequency while the effect of the pressure pulsation caused by cavitation on main frequency is not obvious. With the development of cavitation, the pressure fluctuation induced by cavitation becomes more serious especially for the main frequency, secondary frequency and pulsating amplitude while the head pulsation frequency is given priority to low frequency pulse. Under serious cavitation condition, the head pulsation frequency is given priority to irregular changes of pulse high frequency, and also contains almost regular changes of low frequency. (authors)

Influences of hydrodynamic conditions, nozzle geometry on appearance of high submerged cavitating jets

Directory of Open Access Journals (Sweden)

Hutli Ezddin

2013-01-01

Full Text Available Based on visualization results of highly-submerged cavitating water jet obtained with digital camera, the influences of related parameters such as: injection pressure, nozzle diameter and geometry, nozzle mounting (for convergent / divergent flow, cavitation number and exit jet velocity, were investigated. In addition, the influence of visualization system position was also studied. All the parameters have been found to be of strong influence on the jet appearance and performance. Both hydro-dynamical and geometrical parameters are playing the main role in behavior and intensity of cavitation phenomenon produced by cavitating jet generator. Based on our considerable previous experience in working with cavitating jet generator, the working conditions were chosen in order to obtain measurable phenomenon. [Projekat Ministarstva nauke Republike Srbije, br. TR35046

CFD analysis of the hydrodynamic and cavitation performances of modified NACA 4418 hydrofoil

International Nuclear Information System (INIS)

Markov, Zoran; Popovski, Predrag; Lipej, Andrej

2001-01-01

The paper presents the analysis of the possibilities of using Computational Fluid Dynamics technology for calculating of the flow parameters in a cavitation tunnel. Different turbulence models are used to perform the calculations. Comparison of the results from the experimental work and the CFD-TASC flow analysis are presented. Cavitation is addressed as a particular phenomenon, but also its influence on the hydrodynamic parameters. Constant enthalpy vaporization model is used for this purpose and the results will be compared with the photos taken during the cavitation investigation in the tunnel. (Original)

Optimization of biodiesel production in a hydrodynamic cavitation reactor using used frying oil.

Science.gov (United States)

Ghayal, Dyneshwar; Pandit, Aniruddha B; Rathod, Virendra K

2013-01-01

The present work demonstrates the application of a hydrodynamic cavitation reactor for the synthesis of biodiesel with used frying oil as a feedstock. The synthesis involved the transesterification of used frying oil (UFO) with methanol in the presence of potassium hydroxide as a catalyst. The effect of geometry and upstream pressure of a cavitating orifice plate on the rate of transesterification reaction has been studied. It is observed that the micro level turbulence created by hydrodynamic cavitation somewhat overcomes the mass transfer limitations for triphasic transesterification reaction. The significant effects of upstream pressure on the rate of formation of methyl esters have been seen. It has been observed that flow geometry of orifice plate plays a crucial role in process intensification. With an optimized plate geometry of 2mm hole diameter and 25 holes, more than 95% of triglycerides have been converted to methyl esters in 10 min of reaction time with cavitational yield of 1.28 × 10(-3) (Grams of methyl esters produced per Joule of energy supplied). The potential of UFO to produce good quality methyl esters has been demonstrated. Copyright © 2012 Elsevier B.V. All rights reserved.

Degradation of reactive orange 4 dye using hydrodynamic cavitation based hybrid techniques.

Science.gov (United States)

Gore, Mohan M; Saharan, Virendra Kumar; Pinjari, Dipak V; Chavan, Prakash V; Pandit, Aniruddha B

2014-05-01

In the present work, degradation of reactive orange 4 dye (RO4) has been investigated using hydrodynamic cavitation (HC) and in combination with other AOP's. In the hybrid techniques, combination of hydrodynamic cavitation and other oxidizing agents such as H2O2 and ozone have been used to get the enhanced degradation efficiency through HC device. The hydrodynamic cavitation was first optimized in terms of different operating parameters such as operating inlet pressure, cavitation number and pH of the operating medium to get the maximum degradation of RO4. Following the optimization of HC parameters, the degradation of RO4 was carried out using the combination of HC with H2O2 and ozone. It has been found that the efficiency of the HC can be improved significantly by combining it with H2O2 and ozone. The mineralization rate of RO4 increases considerably with 14.67% mineralization taking place using HC alone increases to 31.90% by combining it with H2O2 and further increases to 76.25% through the combination of HC and ozone. The synergetic coefficient of greater than one for the hybrid processes of HC+H2O2 and HC+Ozone has suggested that the combination of HC with other oxidizing agents is better than the individual processes for the degradation of dye effluent containing RO4. The combination of HC with ozone proves to be the most energy efficient method for the degradation of RO4 as compared to HC alone and the hybrid process of HC and H2O2. Copyright © 2013 Elsevier B.V. All rights reserved.

Treatment of industrial wastewater effluents using hydrodynamic cavitation and the advanced Fenton process.

Science.gov (United States)

Chakinala, Anand G; Gogate, Parag R; Burgess, Arthur E; Bremner, David H

2008-01-01

For the first time, hydrodynamic cavitation induced by a liquid whistle reactor (LWR) has been used in conjunction with the advanced Fenton process (AFP) for the treatment of real industrial wastewater. Semi-batch experiments in the LWR were designed to investigate the performance of the process for two different industrial wastewater samples. The effect of various operating parameters such as pressure, H2O2 concentration and the initial concentration of industrial wastewater samples on the extent of mineralization as measured by total organic carbon (TOC) content have been studied with the aim of maximizing the extent of degradation. It has been observed that higher pressures, sequential addition of hydrogen peroxide at higher loadings and lower concentration of the effluent are more favourable for a rapid TOC mineralization. In general, the novel combination of hydrodynamic cavitation with AFP results in about 60-80% removal of TOC under optimized conditions depending on the type of industrial effluent samples. The combination described herein is most useful for treatment of bio-refractory materials where the diminution in toxicity can be achieved up to a certain level and then conventional biological oxidation can be employed for final treatment. The present work is the first to report the use of a hydrodynamic cavitation technique for real industrial wastewater treatment.

Disinfection of Escherichia coli bacteria using hybrid method of ozonation and hydrodynamic cavitation with orifice plate

Science.gov (United States)

Karamah, Eva F.; Ghaudenson, Rioneli; Amalia, Fitri; Bismo, Setijo

2017-11-01

This research aims to evaluate the performance of hybrid method of ozonation and hydrodynamic cavitation with orifice plate on E.coli bacteria disinfection. In this research, ozone dose, circulation flowrate, and disinfection method were varied. Ozone was produced by commercial ozonator with ozone dose of 64.83 mg/hour, 108.18 mg/hour, and 135.04 mg/hour. Meanwhile, hydrodynamic cavitation was generated by an orifice plate. The disinfection method compared in this research were: hydrodynamic cavitation, ozonation, and the combination of both. The best result on each method was achieved on the 60th minutes and with a circulation flowrate of 7 L/min. The hybrid method attained final concentration of 0 CFU/mL from the initial concentration of 2.10 × 105 CFU/mL. The ozonation method attained final concentration of 0 CFU/mL from the initial concentration of 1.32 × 105 CFU/mL. Cavitation method gives the least disinfection with final concentration of 5.20 × 104 CFU/mL from the initial concentration of 2.17 × 105 CFU/mL. In conclusion, hybrid method gives a faster and better disinfection of E.coli than each method on its own.

Inactivation of Heterosigma akashiwo in ballast water by circular orifice plate-generated hydrodynamic cavitation.

Science.gov (United States)

Feng, Daolun; Zhao, Jie; Liu, Tian

2016-01-01

The discharge of alien ballast water is a well-known, major reason for marine species invasion. Here, circular orifice plate-generated hydrodynamic cavitation was used to inactivate Heterosigma akashiwo in ballast water. In comparison with single- and multihole orifice plates, the conical-hole orifice plate yielded the highest inactivation percentage, 51.12%, and consumed only 6.84% energy (based on a 50% inactivation percentage). Repeating treatment, either using double series-connection or circling inactivation, elevated the inactivation percentage, yet consumed much more energy. The results indicate that conical-hole-generated hydrodynamic cavitation shows great potential as a pre-inactivation method for ballast water treatment.

Intensification of biogas production using pretreatment based on hydrodynamic cavitation.

Science.gov (United States)

Patil, Pankaj N; Gogate, Parag R; Csoka, Levente; Dregelyi-Kiss, Agota; Horvath, Miklos

2016-05-01

The present work investigates the application of hydrodynamic cavitation (HC) for the pretreatment of wheat straw with an objective of enhancing the biogas production. The hydrodynamic cavitation reactor is based on a stator and rotor assembly. The effect of three different speeds of rotor (2300, 2500, 2700 rpm), wheat straw to water ratios (0.5%, 1% and 1.5% wt/wt) and also treatment times as 2, 4 and 6 min have been investigated in the work using the design of experiments (DOE) approach. It was observed that the methane yield of 31.8 ml was obtained with untreated wheat straw whereas 77.9 ml was obtained with HC pre-treated wheat straw confirming the favourable changes during the pre-treatment. The combined pre-treatment using KOH and HC gave maximum yield of biogas as 172.3 ml. Overall, it has been established that significant enhancement in the biogas production can be obtained due to the pretreatment using HC which can also be further intensified by combination with chemical treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

Removal of pharmaceuticals from wastewater by biological processes, hydrodynamic cavitation and UV treatment.

Science.gov (United States)

Zupanc, Mojca; Kosjek, Tina; Petkovšek, Martin; Dular, Matevž; Kompare, Boris; Širok, Brane; Blažeka, Željko; Heath, Ester

2013-07-01

To augment the removal of pharmaceuticals different conventional and alternative wastewater treatment processes and their combinations were investigated. We tested the efficiency of (1) two distinct laboratory scale biological processes: suspended activated sludge and attached-growth biomass, (2) a combined hydrodynamic cavitation-hydrogen peroxide process and (3) UV treatment. Five pharmaceuticals were chosen including ibuprofen, naproxen, ketoprofen, carbamazepine and diclofenac, and an active metabolite of the lipid regulating agent clofibric acid. Biological treatment efficiency was evaluated using lab-scale suspended activated sludge and moving bed biofilm flow-through reactors, which were operated under identical conditions in respect to hydraulic retention time, working volume, concentration of added pharmaceuticals and synthetic wastewater composition. The suspended activated sludge process showed poor and inconsistent removal of clofibric acid, carbamazepine and diclofenac, while ibuprofen, naproxen and ketoprofen yielded over 74% removal. Moving bed biofilm reactors were filled with two different types of carriers i.e. Kaldnes K1 and Mutag BioChip™ and resulted in higher removal efficiencies for ibuprofen and diclofenac. Augmentation and consistency in the removal of diclofenac were observed in reactors using Mutag BioChip™ carriers (85%±10%) compared to reactors using Kaldnes carriers and suspended activated sludge (74%±22% and 48%±19%, respectively). To enhance the removal of pharmaceuticals hydrodynamic cavitation with hydrogen peroxide process was evaluated and optimal conditions for removal were established regarding the duration of cavitation, amount of added hydrogen peroxide and initial pressure, all of which influence the efficiency of the process. Optimal parameters resulted in removal efficiencies between 3-70%. Coupling the attached-growth biomass biological treatment, hydrodynamic cavitation/hydrogen peroxide process and UV treatment

Effect of hydrodynamic cavitation on the rate of OH-radical formation in the presence of hydrogen peroxide

Science.gov (United States)

Aseev, D. G.; Batoeva, A. A.

2014-01-01

It is shown experimentally that hydrogen peroxide is the source of OH-radicals at low-pressure hydrodynamic cavitation. Major preconditions for the intensification of oxidative destruction processes in organic pollutants with an added cavitation stimulus are determined.

Energy Efficiency for Biodiesel Production by Combining Two Orifices in Hydrodynamic Cavitation Reactor

OpenAIRE

Mahlinda, Mahlinda; Djafar, Fitriana

2014-01-01

Research of energy efficiency for biodiesel production process by combining two orifices on  hydrodynamic cavitation reactor had been carried out. The aim of this reseach was to studied effect of the number of orifices toward increasing temperature without using external energy source to produce biodiesel that generated by cavitation effects on orifices. The results of preliminary research showed by combining two orifices arranged in series can produce the highest thermal energy reached 48oC....

Interaction mechanism of double bubbles in hydrodynamic cavitation

Science.gov (United States)

Li, Fengchao; Cai, Jun; Huai, Xiulan; Liu, Bin

2013-06-01

Bubble-bubble interaction is an important factor in cavitation bubble dynamics. In this paper, the dynamic behaviors of double cavitation bubbles driven by varying pressure field downstream of an orifice plate in hydrodynamic cavitation reactor are examined. The bubble-bubble interaction between two bubbles with different radii is considered. We have shown the different dynamic behaviors between double cavitation bubbles and a single bubble by solving two coupling nonlinear equations using the Runge-Kutta fourth order method with adaptive step size control. The simulation results indicate that, when considering the role of the neighbor smaller bubble, the oscillation of the bigger bubble gradually exhibits a lag in comparison with the single-bubble case, and the extent of the lag becomes much more obvious as time goes by. This phenomenon is more easily observed with the increase of the initial radius of the smaller bubble. In comparison with the single-bubble case, the oscillation of the bigger bubble is enhanced by the neighbor smaller bubble. Especially, the pressure pulse of the bigger bubble rises intensely when the sizes of two bubbles approach, and a series of peak values for different initial radii are acquired when the initial radius ratio of two bubbles is in the range of 0.9˜1.0. Although the increase of the center distance between two bubbles can weaken the mutual interaction, it has no significant influence on the enhancement trend. On the one hand, the interaction between two bubbles with different radii can suppress the growth of the smaller bubble; on the other hand, it also can enhance the growth of the bigger one at the same time. The significant enhancement effect due to the interaction of multi-bubbles should be paid more attention because it can be used to reinforce the cavitation intensity for various potential applications in future.

Application of hydrodynamic cavitation to improve the biodegradability of mature landfill leachate.

Science.gov (United States)

Bis, M; Montusiewicz, A; Ozonek, J; Pasieczna-Patkowska, S

2015-09-01

In this study, the application of hydrodynamic cavitation to improve the biodegradability of mature landfill leachate was investigated. Three configurations of cavitation device were examined and operational parameters of the process were selected. The study indicated that the orifice plate with a 3/10mm diameter conical concentric hole, characterized by the cavitation number of 0.033, is a reasonable choice to ensure the enhanced biodegradability of mature leachate. Using such a configuration and maintaining 30 recirculation passes through the cavitation zone at inlet pressure of 7 bar, the highest increase of biodegradability index (BI) of approximately 22% occurred, i.e., from the value of 0.046 to 0.056. The FT-IR/PAS analysis confirmed a degradation of refractory compounds that typically prevail in mature leachate. An evaluation of energy efficiency was made in terms of the actual consumed energy measured by using the Kyoritsu KEW6310 Power Quality Tester. A cavitational yield of 9.8 mg COD kJ(-1) was obtained for the optimum configuration and 30 recirculation passes. Regarding energy efficiency, the application of 10 cavitation cycles appeared to be the most profitable. This was due to an almost threefold higher cavitational yield of 27.5 mg COD kJ(-1). However, the preferable option should be selected by considering a satisfactory effect in the biodegradability enhancement. Copyright © 2015 Elsevier B.V. All rights reserved.

Occurrence of hydrodynamic cavitation.

Science.gov (United States)

Nosov, V R; Gómez-Mancilla, J C; Meda-Campaña, J A

2011-01-01

In this paper, the conditions under which cavitation (or liquid film rupture) can or cannot occur in thin layers of moving liquid are derived for three typical cases. At the same time, expressions depending on geometrical and movement parameters, where cavitation might start, are given. The results are obtained using simple engineering terms, which can be used in cases whether it is necessary to avoid cavitation or to induce it.

Inactivation of food spoilage microorganisms by hydrodynamic cavitation to achieve pasteurization and sterilization of fluid foods.

Science.gov (United States)

Milly, P J; Toledo, R T; Harrison, M A; Armstead, D

2007-11-01

Hydrodynamic cavitation is the formation of gas bubbles in a fluid due to pressure fluctuations induced by mechanical means. Various high-acid (pH hydrodynamic cavitation reactor to determine if commercial sterility can be achieved at reduced processing temperatures. Sporicidal properties of the process were also tested on a low-acid (pH > [corrected] 4.6) fluid food. Fluid foods were pumped under pressure into a hydrodynamic cavitation reactor and subjected to 2 rotor speeds and flow rates to achieve 2 designated exit temperatures. Thermal inactivation kinetics were used to determine heat-induced lethality for all organisms. Calcium-fortified apple juice processed at 3000 and 3600 rpm rotor speeds on the reactor went through a transient temperature change from 20 to 65.6 or 76.7 degrees C and the total process lethality exceeded 5-log reduction of Lactobacillus plantarum and Lactobacillus sakei cells, and Zygosaccharomyces bailii cells and ascospores. Tomato juice inoculated with Bacillus coagulans spores and processed at 3000 and 3600 rpm rotor speeds endured a transient temperature from 37.8 to 93.3 or 104.4 degrees C with viable CFU reductions of 0.88 and 3.10 log cycles, respectively. Skim milk inoculated with Clostridium sporogenes putrefactive anaerobe 3679 spores and processed at 3000 or 3600 rpm rotor speeds endured a transient temperature from 48.9 to 104.4 or 115.6 degrees C with CFU reductions of 0.69 and 2.84 log cycles, respectively. Utilizing hydrodynamic cavitation to obtain minimally processed pasteurized low-acid and commercially sterilized high-acid fluid foods is possible with appropriate process considerations for different products.

Synergetic effect of combination of AOP's (hydrodynamic cavitation and H2O2) on the degradation of neonicotinoid class of insecticide

International Nuclear Information System (INIS)

Raut-Jadhav, Sunita; Saharan, Virendra Kumar; Pinjari, Dipak; Sonawane, Shirish; Saini, Daulat; Pandit, Aniruddha

2013-01-01

Highlights: • Degradation of imidacloprid using hydrodynamic cavitation based techniques. • Combination of hydrodynamic cavitation and H 2 O 2 shows substantial synergetic effect. • Synergetic coefficient of combined process is 22.79. • Degradation mechanism of imidacloprid has been proposed. -- Abstract: In the present work, degradation of imidacloprid (neonicotinoid class of insecticide) in aqueous solution has been systematically investigated using hydrodynamic cavitation and combination of hydrodynamic cavitation (HC) and H 2 O 2 . Initially, effect of different operating parameters such as inlet pressure to the cavitating device (5–20 bar) and operating pH (2–7.5) has been investigated. Optimization of process parameters was followed by the study of effect of combination of HC and H 2 O 2 process on the rate of degradation of imidacloprid. Significant enhancement in the rate of degradation of imidacloprid has been observed using HC + H 2 O 2 process which lead to a complete degradation of imidacloprid in 45 min of operation using optimal molar ratio of imidacloprid:H 2 O 2 as 1:40. Substantial synergetic effect has been observed using HC + H 2 O 2 process which confer the synergetic coefficient of 22.79. An attempt has been made to investigate and compare the energy efficiency and extent of mineralization of individual and combined processes applied in the present work. Identification of the byproducts formed during degradation of imidacloprid has also been done using LC–MS analysis. The present work has established a fact that hydrodynamic cavitation in combination with H 2 O 2 can be effectively used for degradation of imidacloprid

Effect of process intensifying parameters on the hydrodynamic cavitation based degradation of commercial pesticide (methomyl) in the aqueous solution.

Science.gov (United States)

Raut-Jadhav, Sunita; Saini, Daulat; Sonawane, Shirish; Pandit, Aniruddha

2016-01-01

Methomyl, a carbamate pesticide, is classified as a pesticide of category-1 toxicity and hence shows harmful effects on both human and aquatic life. In the present work, the degradation of methomyl has been studied by using hydrodynamic cavitation reactor (HC) and its combination with intensifying agents such as H2O2, fenton reagent and ozone (hybrid processes). Initially, the optimization of operating parameters such pH and inlet pressure to the cavitating device (circular venturi) has been carried out for maximizing the efficacy of hydrodynamic cavitation. Further degradation study of methomyl by the application of hybrid processes was carried out at an optimal pH of 2.5 and the optimal inlet pressure of 5 bar. Significant synergetic effect has been observed in case of all the hybrid processes studied. Synergetic coefficient of 5.8, 13.41 and 47.6 has been obtained by combining hydrodynamic cavitation with H2O2, fenton process and ozone respectively. Efficacy of individual and hybrid processes has also been obtained in terms of energy efficiency and extent of mineralization. HC+Ozone process has proved to be the most effective process having highest synergetic coefficient, energy efficiency and the extent of mineralization. The study has also encompassed the identification of intermediate by-products generated during the degradation and has proposed the probable degradation pathway. It has been conclusively established that hydrodynamic cavitation in the presence of intensifying agents can effectively be used for complete degradation of methomyl. Copyright © 2015 Elsevier B.V. All rights reserved.

A novel rotation generator of hydrodynamic cavitation for waste-activated sludge disintegration.

Science.gov (United States)

Petkovšek, Martin; Mlakar, Matej; Levstek, Marjetka; Stražar, Marjeta; Širok, Brane; Dular, Matevž

2015-09-01

The disintegration of raw sludge is very important for enhancement of the biogas production in anaerobic digestion process as it provides easily degradable substrate for microorganisms to perform maximum sludge treatment efficiency and stable digestion of sludge at lower costs. In the present study the disintegration was studied by using a novel rotation generator of hydrodynamic cavitation (RGHC). At the first stage the analysis of hydrodynamics of the RGHC were made with tap water, where the cavitation extent and aggressiveness was evaluated. At the second stage RGHC was used as a tool for pretreatment of a waste-activated sludge (WAS), collected from wastewater treatment plant (WWTP). In case of WAS the disintegration rate was measured, where the soluble chemical oxygen demand (SCOD) and soluble Kjeldahl nitrogen were monitored and microbiological pictures were taken. The SCOD increased from initial 45 mg/L up to 602 mg/L and 12.7% more biogas has been produced by 20 passes through RGHC. The results were obtained on a pilot bioreactor plant, volume of 400 L. Copyright © 2015. Published by Elsevier B.V.

Cavitation Inception Scale Effects. 1. Nuclei Distributions in Natural Waters. 2. Cavitation Inception in a Turbulent Shear Flow.

Science.gov (United States)

1987-05-01

cavitation is pressure-controlled. The term hydrodynamic cavitation is some- times used to stress the dominant role of dynamic pressure in the cavitation...Diffraction Pattern of Opaque and Transparent Objects with Coherent Back- ground," Optica Acta, 11, 183-193. Peterson, F.B. (1972), " Hydrodynamic Cavitation and

Degradation of 4-chloro 2-aminophenol using a novel combined process based on hydrodynamic cavitation, UV photolysis and ozone.

Science.gov (United States)

Barik, Arati J; Gogate, Parag R

2016-05-01

The degradation of 4-chloro 2-aminophenol (4C2AP), an acute toxic organic compound, has been studied using different approaches based on the hydrodynamic cavitation (HC) with orifice plate as cavitating device, photolysis (UV) and ozonation (O3). The dependency of extent of degradation on operating parameters like operating pressure (2-5 bar), initial pH (3-8) and temperature (30-38 °C) have been established initially to maximize the efficacy of hydrodynamic cavitation. Subsequently the degradation has been studied using combined treatment strategies as HC+UV, HC+O3, UV+O3 and HC+UV+O3 at the established optimum parameters of operating temperature as 30 °C, initial pH of 6 and inlet pressure of 4 bar. The maximum extent of degradation as 96.85% and 73.6% reduction in TOC has been obtained using hydrodynamic cavitation in combination with UV photolysis and ozonation under the optimized operating conditions. The degradation products of 4C2AP have been identified using GC-MS. The present work has clearly established the efficacy of combined treatment approach (HC+UV+O3) for the removal of organic pollutant for the first time. Copyright © 2015 Elsevier B.V. All rights reserved.

Degradation of alachlor in aqueous solution by using hydrodynamic cavitation.

Science.gov (United States)

Wang, Xikui; Zhang, Yong

2009-01-15

The degradation of alachlor aqueous solution by using hydrodynamic cavitation was systematically investigated. It was found that alachlor in aqueous solution can be deomposed with swirling jet-induced cavitation. The degradation can be described by a pseudo-first-order kinetics and the degradation rate was found to be 4.90x10(-2)min(-1). The effects of operating parameters such as fluid pressure, solution temperature, initial concentration of alachlor and medium pH on the degradation rates of alachlor were also discussed. The results showed that the degradation rates of alachlor increased with increasing pressure and decreased with increasing initial concentration. An optimum temperature of 40 degrees C existed for the degradation rate of alachlor and the degradation rate was also found to be slightly depend on medium pH. Many degradation products formed during the process, and some of them were qualitatively identified by GC-MS.

Decontamination of unsymmetrical dimethylhydrazine waste water by hydrodynamic cavitation-induced advanced Fenton process.

Science.gov (United States)

Torabi Angaji, Mahmood; Ghiaee, Reza

2015-03-01

A pilot scale hydrodynamic cavitation (HC) reactor, using iron metal blades, as the heterogeneous catalyst, with no external source of H₂O₂ was developed for catalytic decontamination of unsymmetrical dimethylhydrazine (UDMH) waste water. In situ generation of Fenton reagents suggested an induced advanced Fenton process (IAFP) to explain the enhancing effect of the used catalyst in the HC process. The effects of the applied catalyst, pH of the initial solution (1.0-9.7), initial UDMH concentration (2-15 mg/l), inlet pressure (5.5-7.8bar), and downstream pressure (2-6 bar), have been investigated. The results showed that the highest cavitation yield can be obtained at pH 3 and initial UDMH concentration of 10mg/l. Also, an increase in the inlet pressure would lead to an increase in the extent of UDMH degradation. In addition, the optimum value of 3 bar was determined for the downstream pressure that resulted to 98.6% degradation of UDMH after 120 min of processing time. Neither n-nitrosodimethylamine (NDMA) nor any other toxic byproduct (/end-product) was observed in the investigated samples. Formic acid and acetic acid, as well as nitromethane, were identified as oxidation by-products. The present work has conclusively established that hydrodynamic cavitation in combination with Fenton's chemistry can be effectively used for the degradation of UDMH. Copyright © 2014 Elsevier B.V. All rights reserved.

Acoustic cavitation studies

Science.gov (United States)

Crum, L. A.

1981-09-01

The primary thrust of this study was toward a more complete understanding of general aspects of acoustic cavitation. The effect of long-chain polymer additives on the cavitation threshold was investigated to determine if they reduced the acoustic cavitation threshold in a similar manner to the observed reduction in the cavitation index in hydrodynamic cavitation. Measurements were made of the acoustic cavitation threshold as a function of polymer concentration for additives such as guar gum and polyethelene oxide. The measurements were also made as a function of dissolved gas concentration, surface tension and viscosity. It was determined that there was a significant increase in the acoustic cavitation threshold for increased concentrations of the polymer additives (measurable effects could be obtained for concentrations as low as a few parts per million). One would normally expect that an additive that reduces surface tension to decrease the pressure required to cause a cavity to grow and thus these additives, at first thought, should reduce the threshold. However, even in the hydrodynamic case, the threshold was increased. In both of the hydrodynamic cases considered, the explanation for the increased threshold was given in terms of changed fluid dynamics rather than changed physical properties of the fluid.

Hydrodynamic cavitation: characterization of a novel design with energy considerations for the inactivation of Saccharomyces cerevisiae in apple juice.

Science.gov (United States)

Milly, P J; Toledo, R T; Kerr, W L; Armstead, D

2008-08-01

A Shockwave Power Reactor consisting of an annulus with a rotating pock-marked inner cylinder was used to induce hydrodynamic cavitation in calcium-fortified apple juice flowing in the annular space. Lethality on Saccharomyces cerevisiae was assessed at processing temperatures of 65 and 76.7 degrees C. Details of the novel equipment design were presented and energy consumption was compared to conventional and pulsed electric fields processing technologies. The mean log cycle reduction of S. cerevisiae was 6.27 CFU/mL and all treatments resulted in nonrecoverable viable cells. Induced lethality from hydrodynamic cavitation on S. cerevisiae exceeded the predicted values based on experimentally determined thermal resistance. Rotation of 3000 and 3600 rpm at flow rates greater than 1.0 L/min raised product temperature from 20 to 65.6 or 76.7 degrees C, respectively, and energy input was less than 220 kJ/kg. Conversion efficiency from electrical to thermal was 55% to 84%. Hydrodynamic cavitation enhanced lethality of spoilage microorganisms in minimally processed juices and reduced energy usage.

Influence of the bubbles on the turbulence in the liquid in hydrodynamic cavitation through a venturi

Science.gov (United States)

Fuzier, Sylvie; Coutier Delgosha, Olivier; Coudert, S. Ébastien; Dazin, Antoine

2011-11-01

The physical description of hydrodynamic cavitation is complex as it includes strongly unsteady, turbulent and phase change phenomena. Because the bubbles in the cavitation area render this zone opaque, nonintrusive experimental observation inside this zone is difficult and little is known about the detailed bubble, flow structure and physics inside. A novel approach using LIF-PIV to investigate the dynamics inside the cavitation area generated through a venturi is presented. The velocity in the liquid and of the bubbles are measured simultaneously and correlated with areas of various bubble structure. The influence of the bubble structure on the turbulence in the liquid is also studied.

Influence of hydrodynamic cavitation on the rheological properties and microstructure of formulated Greek-style yogurts.

Science.gov (United States)

Meletharayil, G H; Metzger, L E; Patel, Hasmukh A

2016-11-01

With limited applications of acid whey generated during the manufacture of Greek yogurts, an alternate processing technology to sidestep the dewheying process was developed. Milk protein concentrate (MPC) and carbon dioxide-treated milk protein concentrate (TMPC) were used as sources of protein to fortify skim milk to 9% (wt/wt) protein for the manufacture of Greek-style yogurts (GSY). The GSY bases were inoculated and fermented with frozen direct vat set yogurt culture to a pH of 4.6. Owing to the difference in buffering of MPC and TMPC, GSY with TMPC and MPC exhibited different acidification kinetics, with GSY containing TMPC having a lower fermentation time. The GSY with TMPC had a titratable acidity of 1.45% lactic acid and was comparable to acidity of commercial Greek yogurt (CGY). Hydrodynamic cavitation at 4 different rotor speeds (0, 15, 30, and 60 Hz) as a postfermentation tool reduced the consistency coefficient (K) of GSY containing TMPC from 79.4 Pa·s n at 0 Hz to 17.59 Pa·s n at 60 Hz. Similarly for GSY containing MPC, K values decreased from 165.74 Pa·s n at 0 Hz to 53.04 Pa·s n at 60 Hz. The apparent viscosity (η 100 ) was 0.25 Pa·s for GSY containing TMPC and 0.66 Pa·s for GSY containing MPC at 60 Hz. The CGY had a η 100 value of 0.74 Pa·s. Small amplitude rheological analysis performed on GSY indicated a loss of elastic modulus dependency on frequency caused by the breakdown of protein interactions with increasing cavitator rotor speeds. A steady decrease in hardness and adhesiveness values of GSY was observed with increasing cavitational intensities. Numbers of grains with a perimeter of >1mm of cavitated GSY with TMPC and MPC were 35 and 13 grains/g of yogurt, respectively, and were lower than 293 grains/g observed in CGY. The water-holding capacity of GSY was higher than that observed for a commercial strained Greek yogurt. The ability to scale up the process of hydrodynamic cavitation industrially, and the ease of controlling events of

Synergetic effect of combination of AOP's (hydrodynamic cavitation and H₂O₂) on the degradation of neonicotinoid class of insecticide.

Science.gov (United States)

Raut-Jadhav, Sunita; Saharan, Virendra Kumar; Pinjari, Dipak; Sonawane, Shirish; Saini, Daulat; Pandit, Aniruddha

2013-10-15

In the present work, degradation of imidacloprid (neonicotinoid class of insecticide) in aqueous solution has been systematically investigated using hydrodynamic cavitation and combination of hydrodynamic cavitation (HC) and H2O2. Initially, effect of different operating parameters such as inlet pressure to the cavitating device (5-20 bar) and operating pH (2-7.5) has been investigated. Optimization of process parameters was followed by the study of effect of combination of HC and H2O2 process on the rate of degradation of imidacloprid. Significant enhancement in the rate of degradation of imidacloprid has been observed using HC+H2O2 process which lead to a complete degradation of imidacloprid in 45 min of operation using optimal molar ratio of imidacloprid:H2O2 as 1:40. Substantial synergetic effect has been observed using HC+H2O2 process which confer the synergetic coefficient of 22.79. An attempt has been made to investigate and compare the energy efficiency and extent of mineralization of individual and combined processes applied in the present work. Identification of the byproducts formed during degradation of imidacloprid has also been done using LC-MS analysis. The present work has established a fact that hydrodynamic cavitation in combination with H2O2 can be effectively used for degradation of imidacloprid. Copyright © 2013 Elsevier B.V. All rights reserved.

A novel microfluidic mixer based on dual-hydrodynamic focusing for interrogating the kinetics of DNA-protein interaction.

Science.gov (United States)

Li, Ying; Xu, Fei; Liu, Chao; Xu, Youzhi; Feng, Xiaojun; Liu, Bi-Feng

2013-08-21

Kinetic measurement of biomacromolecular interaction plays a significant role in revealing the underlying mechanisms of cellular activities. Due to the small diffusion coefficient of biomacromolecules, it is difficult to resolve the rapid kinetic process with traditional analytical methods such as stopped-flow or laminar mixers. Here, we demonstrated a unique continuous-flow laminar mixer based on microfluidic dual-hydrodynamic focusing to characterize the kinetics of DNA-protein interactions. The time window of this mixer for kinetics observation could cover from sub-milliseconds to seconds, which made it possible to capture the folding process with a wide dynamic range. Moreover, the sample consumption was remarkably reduced to <0.55 μL min⁻¹, over 1000-fold saving in comparison to those reported previously. We further interrogated the interaction kinetics of G-quadruplex and the single-stranded DNA binding protein, indicating that this novel micromixer would be a useful approach for analyzing the interaction kinetics of biomacromolecules.

Synergetic effect of combination of AOP's (hydrodynamic cavitation and H{sub 2}O{sub 2}) on the degradation of neonicotinoid class of insecticide

Energy Technology Data Exchange (ETDEWEB)

Raut-Jadhav, Sunita [Vishwakarma Institute of Technology, Pune 411037 (India); Saharan, Virendra Kumar [Chemical Engineering Department, M. N. I. T, Jaipur, Rajasthan, 302001 (India); Pinjari, Dipak [Chemical Engineering Department, Institute of Chemical Technology, (ICT), Matunga, Mumbai, 400019 (India); Sonawane, Shirish, E-mail: shirishsonawane09@gmail.com [Chemical Engineering Department, N. I. T Warangal, Andhra Pradesh 506004 (India); Saini, Daulat, E-mail: dsaini2010@gmail.com [National Chemical Laboratory, Pune, 411008 (India); Pandit, Aniruddha, E-mail: dr.pandit@gmail.com [Chemical Engineering Department, Institute of Chemical Technology, (ICT), Matunga, Mumbai, 400019 (India)

2013-10-15

Highlights: • Degradation of imidacloprid using hydrodynamic cavitation based techniques. • Combination of hydrodynamic cavitation and H{sub 2}O{sub 2} shows substantial synergetic effect. • Synergetic coefficient of combined process is 22.79. • Degradation mechanism of imidacloprid has been proposed. -- Abstract: In the present work, degradation of imidacloprid (neonicotinoid class of insecticide) in aqueous solution has been systematically investigated using hydrodynamic cavitation and combination of hydrodynamic cavitation (HC) and H{sub 2}O{sub 2}. Initially, effect of different operating parameters such as inlet pressure to the cavitating device (5–20 bar) and operating pH (2–7.5) has been investigated. Optimization of process parameters was followed by the study of effect of combination of HC and H{sub 2}O{sub 2} process on the rate of degradation of imidacloprid. Significant enhancement in the rate of degradation of imidacloprid has been observed using HC + H{sub 2}O{sub 2} process which lead to a complete degradation of imidacloprid in 45 min of operation using optimal molar ratio of imidacloprid:H{sub 2}O{sub 2} as 1:40. Substantial synergetic effect has been observed using HC + H{sub 2}O{sub 2} process which confer the synergetic coefficient of 22.79. An attempt has been made to investigate and compare the energy efficiency and extent of mineralization of individual and combined processes applied in the present work. Identification of the byproducts formed during degradation of imidacloprid has also been done using LC–MS analysis. The present work has established a fact that hydrodynamic cavitation in combination with H{sub 2}O{sub 2} can be effectively used for degradation of imidacloprid.

Applying the technology of hydrodynamic cavitation treatment of high-viscosity oils to increase the efficiency of transportation

Science.gov (United States)

Brand, A. E.; Vershinina, S. V.; Vengerov, A. A.; Mostovaya, N. A.

2015-10-01

The article investigates the possibility of applying hydrodynamic cavitation treatment to reduce oil viscosity in Russian pipeline transportation system and increase its performance. The result of laboratory tests and suggestions on technology application are given

Hydrodynamic cavitation applied to industrial wastewater; Tratamiento de efluentes industriales mediante cavitacion hidrodinamica

Energy Technology Data Exchange (ETDEWEB)

Benito, Y; Arrojo, S

2006-07-01

The use environmental technology of the phenomenon known as cavitation has opened in the last new years alternatives for the treatment especially for industrial effluents. CIEMAT has designed and constructed a plant of cavitation hydrodynamics to take to end experiments that it allows us to show the possibilities of this technology as process of advanced oxidation of low cost. The experimentation has been made with water contaminated by substances like toluene and some derivatives, chloride organic compounds, xylenes, ammonia, wastewater from the ended of leather sector, there being achieved important reductions of the DQO (of the order of 60%) in short times. This work shows the results obtained in the experimentation of waters contaminated with toluene and p-nitrophenol. (Author)

Multifocal laser surgery: cutting enhancement by hydrodynamic interactions between cavitation bubbles.

Science.gov (United States)

Toytman, I; Silbergleit, A; Simanovski, D; Palanker, D

2010-10-01

Transparent biological tissues can be precisely dissected with ultrafast lasers using optical breakdown in the tight focal zone. Typically, tissues are cut by sequential application of pulses, each of which produces a single cavitation bubble. We investigate the hydrodynamic interactions between simultaneous cavitation bubbles originating from multiple laser foci. Simultaneous expansion and collapse of cavitation bubbles can enhance the cutting efficiency, by increasing the resulting deformations in tissue, and the associated rupture zone. An analytical model of the flow induced by the bubbles is presented and experimentally verified. The threshold strain of the material rupture is measured in a model tissue. Using the computational model and the experimental value of the threshold strain one can compute the shape of the rupture zone in tissue resulting from application of multiple bubbles. With the threshold strain of 0.7 two simultaneous bubbles produce a continuous cut when applied at the distance 1.35 times greater than that required in sequential approach. Simultaneous focusing of the laser in multiple spots along the line of intended cut can extend this ratio to 1.7. Counterpropagating jets forming during collapse of two bubbles in materials with low viscosity can further extend the cutting zone-up to approximately a factor of 1.5.

Hydrodynamic Cavitation through “Labs on a Chip”: From Fundamentals to Applications

OpenAIRE

Ayela , Frederic; Cherief , Wahid; Colombet , Damien; Ledoux , Gilles; Martini , Mateo; Mossaz , Stephane; Podbevsek , Darjan; Qiu , Xiaoyu; Tillement , Olivier

2017-01-01

International audience; Monitoring hydrodynamic cavitation of liquids through “labs on a chip” (i.e. microchannels with a shrinkage, such as microdiaphragms or microventuris) is an improvement in experimental approaches devoted to study the mechanisms involved in these multiphase flows. The small sizes of the reactors do not require big substructures. Flow rates of around 1 L/h make possible the characterisation of rare, toxic or expensive pure fluids or mixtures. Moreover, because of that mi...

Application of Technology of Hydrodynamic Cavitation Processing High-Viscosity Oils for the Purpose of Improving the Rheological Characteristics of Oils

Science.gov (United States)

Zemenkov, Y. D.; Zemenkova, M. Y.; Vengerov, A. A.; Brand, A. E.

2016-10-01

There is investigated the technology of hydrodynamic cavitational processing viscous and high-viscosity oils and the possibility of its application in the pipeline transport system for the purpose of increasing of rheological properties of the transported oils, including dynamic viscosity shear stress in the article. It is considered the possibility of application of the combined hydrodynamic cavitational processing with addition of depressor additive for identification of effect of a synergism. It is developed the laboratory bench and they are presented results of modeling and laboratory researches. It is developed the hardware and technological scheme of application of the developed equipment at industrial objects of pipeline transport.

Degradation of 2,4-dinitrophenol using a combination of hydrodynamic cavitation, chemical and advanced oxidation processes.

Science.gov (United States)

Bagal, Manisha V; Gogate, Parag R

2013-09-01

In the present work, degradation of 2,4-dinitrophenol (DNP), a persistent organic contaminant with high toxicity and very low biodegradability has been investigated using combination of hydrodynamic cavitation (HC) and chemical/advanced oxidation. The cavitating conditions have been generated using orifice plate as a cavitating device. Initially, the optimization of basic operating parameters have been done by performing experiments over varying inlet pressure (over the range of 3-6 bar), temperature (30 °C, 35 °C and 40 °C) and solution pH (over the range of 3-11). Subsequently, combined treatment strategies have been investigated for process intensification of the degradation process. The effect of HC combined with chemical oxidation processes such as hydrogen peroxide (HC/H2O2), ferrous activated persulfate (HC/Na2S2O8/FeSO4) and HC coupled with advanced oxidation processes such as conventional Fenton (HC/FeSO4/H2O2), advanced Fenton (HC/Fe/H2O2) and Fenton-like process (HC/CuO/H2O2) on the extent of degradation of DNP have also been investigated at optimized conditions of pH 4, temperature of 35 °C and inlet pressure of 4 bar. Kinetic study revealed that degradation of DNP fitted first order kinetics for all the approaches under investigation. Complete degradation with maximum rate of DNP degradation has been observed for the combined HC/Fenton process. The energy consumption analysis for hydrodynamic cavitation based process has been done on the basis of cavitational yield. Degradation intermediates have also been identified and quantified in the current work. The synergistic index calculated for all the combined processes indicates HC/Fenton process is more feasible than the combination of HC with other Fenton like processes. Copyright © 2013 Elsevier B.V. All rights reserved.

Harness cavitation to improve processing

Energy Technology Data Exchange (ETDEWEB)

Pandit, A.G.; Moholkar, V.S. [Univ. of Bombay (India)

1996-07-01

Mention cavitation to most chemical engineers, and they undoubtedly think of it as an operational problem. Indeed, the rapid creation and then collapse of bubbles, which is after all what cavitation involves, can destroy pumps and erode other equipment. Cavitation, however, also can have a positive side--presuming it is designed for and not unplanned. In this article, the authors look at how cavitation can be harnessed to improve processes, and the mechanisms for inducing cavitation--ultrasonics and hydrodynamics--and their likely roles. Sonication, that is, the use of ultrasound, is the conventional approach for creating cavitation, and so they turn to it first. Over the past few years, a number of groups have attempted to solve the problem of scale-up and design of ultrasonic reactors. The authors review the systems that already exist and also explore a simpler and efficient alternative to the ultrasonic reactor, the hydrodynamic cavitation reactor.

The efficiency of a new hydrodynamic cavitation pilot system on Artemia salina cysts and natural population of copepods and bacteria under controlled mesocosm conditions.

Science.gov (United States)

Cvetković, Martina; Grego, Mateja; Turk, Valentina

2016-04-15

A study of the efficiency of hydrodynamic cavitation and separation was carried out to evaluate an innovative, environmentally safe and acceptable system for ballast water treatment for reducing the risk of introducing non-native species worldwide. Mesocosm experiments were performed to assess the morphological changes and viability of zooplankton (copepods), Artemia salina cysts, and the growth potential of marine bacteria after the hydrodynamic cavitation treatment with a different number of cycles. Our preliminary results confirmed the significant efficiency of the treatment since more than 98% of the copepods and A. salina cysts were damaged, in comparison with the initial population. The efficiency increased with the number of the hydrodynamic cavitation cycles, or in combination with a separation technique for cysts. There was also a significant decrease in bacterial abundance and growth rate, compared to the initial number and growth potential. Copyright © 2015 Elsevier Ltd. All rights reserved.

Removal of Microcystis aeruginosa using hydrodynamic cavitation: performance and mechanisms.

Science.gov (United States)

Li, Pan; Song, Yuan; Yu, Shuili

2014-10-01

Algal blooms are a seasonal problem in eutrophic water bodies, and novel approaches to algal removal are required. The effect of hydrodynamic cavitation (HC) on the removal of Microcystis aeruginosa was investigated using a laboratory scale device. Samples treated by HC were subsequently grown under illuminated culture conditions. The results demonstrated that a short treatment with HC could effectively settle naturally growing M. aeruginosa without breaking cells. Algal cell density and chlorophyll-a of a sample treated for 10 min were significantly decreased by 88% andv 94%, respectively, after 3 days culture. Various HC operating parameters were investigated, showing that inhibition of M. aeruginosa growth mainly depended on treatment time and pump pressure. Electron microscopy confirmed that sedimentation of algae was attributable to the disruption of intracellular gas vesicles. Damage to the photosynthetic apparatus also contributed to the inhibition of algal growth. Free radicals produced by the cavitation process could be as an indirect indicator of the intensity of HC treatment, although they inflicted minimal damage on the algae. In conclusion, we suggest that HC represents a potentially highly effective and sustainable approach to the removal of algae from water systems. Copyright © 2014 Elsevier Ltd. All rights reserved.

Surface mechanics design by cavitation peening

Directory of Open Access Journals (Sweden)

Hitoshi Soyama

2015-07-01

Full Text Available Although impacts at cavitation bubble collapses cause severe damage in hydraulic machineries, the cavitation impacts can be utilised for surface mechanics design such as introduction of compressive residual stress and/or improvement of fatigue strength. The peening method using the cavitation impacts was called as cavitation peening. In order to reveal the peening intensity of hydrodynamic cavitation and laser cavitation, the arc height of Almen strip and duralumin plate were measured. In the case of hydrodynamic cavitation, cavitation was generated by injecting a high speed water jet into water with a pressurised chamber and an open chamber, and the cavitating jet in air was also examined. The laser cavitation was produced by a pulse laser, and a high speed observation using a high speed video camera was carried out to clarify laser abrasion and laser cavitation with detecting noise by a hydrophone. It was concluded that the peening intensity by using the cavitating jet in water with the pressurized chamber was most aggressive, and the impact induced by the laser cavitation was larger than that of the laser abrasion at the present condition.

Travelling Bubble Cavitation and Resulting Noise.

Science.gov (United States)

1981-03-02

pp. 22-26, 1968. 16. Il’ichev, V. I. "Statistical Model of the Onset of Hydrodynamic Cavitation Noise," Sixth All-Union Acoustic Conference...Collected Papers, Moscow, 1968. 17. Lyamshev, L. M. "On the Theory of Hydrodynamic Cavitation Noise," Soviet Physics-Acoustics, Vol. 15, pp. 494-498, 1970. 18

Observations of the Dynamics and Acoustics of Travelling Bubble Cavitation

Science.gov (United States)

1990-06-25

Bubbles 6.1 Introduction The detailed relationship between the collapse mechanism of hydrodynamic cavitation bubbles and the resulting noise generation is...Contribution to 11th International Towing Tank Conference. Il’ichev, V. I. 1968. Statistical Model of the Onset of Hydrodynamic Cavitation Noise. Soviet...On the Theory of Hydrodynamic Cavitation Noise. Soviet Physics-Acoustics, Vol. 15, pp. 494-498. Marboe, M. L., Billet, M. L. and Thompson, D. E. 1986

Surface mechanics design by cavitation peening

OpenAIRE

Hitoshi Soyama

2015-01-01

Although impacts at cavitation bubble collapses cause severe damage in hydraulic machineries, the cavitation impacts can be utilised for surface mechanics design such as introduction of compressive residual stress and/or improvement of fatigue strength. The peening method using the cavitation impacts was called as cavitation peening. In order to reveal the peening intensity of hydrodynamic cavitation and laser cavitation, the arc height of Almen strip and duralumin plate were measured. In the...

Energy Efficiency for Biodiesel Production by Combining Two Orifices in Hydrodynamic Cavitation Reactor

Directory of Open Access Journals (Sweden)

Mahlinda Mahlinda

2014-12-01

Full Text Available Research of energy efficiency for biodiesel production process by combining two orifices on  hydrodynamic cavitation reactor had been carried out. The aim of this reseach was to studied effect of the number of orifices toward increasing temperature without using external energy source to produce biodiesel that generated by cavitation effects on orifices. The results of preliminary research showed by combining two orifices arranged in series can produce the highest thermal energy reached 48oC. Result of biodiesel production showed that yield of the highest biodiesel was 96.34% using molar ratio a methanol:oil with comparison 6:1, KOH as catalyst (1% for 50 minutes processing time. For biodiesel quality testing showed all selected parameter met the requirements of the Indonesian National Standard (SNI 04-7182:2006. Identification of biodiesel compound using GCMS showed the biodiesel compounds consisted of methyl oleate, methyl palmitate, acid linoleid, methyl stearate, palmitic acid and oleic acid with the total contents 98.39%.

Development of a novel electric field-assisted modified hydrodynamic cavitation system for disintegration of waste activated sludge.

Science.gov (United States)

Jung, Kyung-Won; Hwang, Min-Jin; Yun, Yeo-Myeong; Cha, Min-Jung; Ahn, Kyu-Hong

2014-09-01

In this current study, we present a modified hydrodynamic cavitation device that combines an electric field to substitute for the chemical addition. A modified HC system is basically an orifice plate and crisscross pipe assembly, in which the crisscross pipe imparts some turbulence, which creates collision events. This study shows that for maximizing disintegration, combining HC system, which called electric field-assisted modified orifice plate hydrodynamic cavitation (EFM-HC) in this study, with an electric field is important. Various HC systems were compared in terms of disintegration of WAS, and, among them, the EFM-HC system exhibited the best performance with the highest disintegration efficiency of 47.0±2.0% as well as the destruction of WAS morphological characteristics. The experimental results clearly show that a conventional HC system was successfully modified. In addition, electric field has a great potential for efficient disintegration of WAS for as a additional option in a combination treatment. This study suggests continued research in this field may lead to an appropriate design for commercial use. Copyright © 2014 Elsevier B.V. All rights reserved.

Luminescence from hydrodynamic cavitation. Method and preliminary analysis

International Nuclear Information System (INIS)

Leighton, T.; Farhat, M.; Field, J.

2001-01-01

This report describes a photon-counting study of the cavitation luminescence produced by flow over a hydrofoil. The object was to obtain quantitative data on the number of photons emitted for various flow conditions and to study the link between the light output and the potential for cavitation damage. The flow experiments were performed in a cavitation tunnel capable of achieving flow velocities of up to ca. 50 m s -1 in the test sections. The experimental hydrofoil was a NACA 009 blade. Parameters varied were the flow velocity, the incident angle of the hydrofoil and the cavitation index. The results show that significant photon counts are recorded when leading edge cavitation takes place and U-shaped vortices (cavities) shed from the main cavity. The photon count increases dramatically as the flow velocity increases or the cavitation index is reduced. Departure from a Poisson distribution in the arrival times of photons at the detector may be related to the way vortices shed from the main cavity. Finally, there is a clear correlation between light output and the conditions which could cause cavitation damage. (author)

Luminescence from hydrodynamic cavitation. Method and preliminary analysis

Energy Technology Data Exchange (ETDEWEB)

Leighton, T.; Farhat, M.; Field, J. [and others

2001-06-01

This report describes a photon-counting study of the cavitation luminescence produced by flow over a hydrofoil. The object was to obtain quantitative data on the number of photons emitted for various flow conditions and to study the link between the light output and the potential for cavitation damage. The flow experiments were performed in a cavitation tunnel capable of achieving flow velocities of up to ca. 50 m s{sup -1} in the test sections. The experimental hydrofoil was a NACA 009 blade. Parameters varied were the flow velocity, the incident angle of the hydrofoil and the cavitation index. The results show that significant photon counts are recorded when leading edge cavitation takes place and U-shaped vortices (cavities) shed from the main cavity. The photon count increases dramatically as the flow velocity increases or the cavitation index is reduced. Departure from a Poisson distribution in the arrival times of photons at the detector may be related to the way vortices shed from the main cavity. Finally, there is a clear correlation between light output and the conditions which could cause cavitation damage. (author)

Simulating the Resonant Acoustic Mixer

Science.gov (United States)

2013-08-02

temperature excursions and void formation. High shear mixing can easily cause fluid cavitation , the sudden formation and catastrophic collapse of tiny voids...high viscosities, this fact does not preclude organized rotational or unstable fluid motion. Purely hydrodynamic instabilities such as Rayleigh...laminar flow equations. Mixing processes for this model are driven by viscous hydrodynamics . Figure 3. Slices of (a) vertical velocity and (b

Enhancing the aggressive intensity of hydrodynamic cavitation through a Venturi tube by increasing the pressure in the region where the bubbles collapse

Science.gov (United States)

Soyama, H.; Hoshino, J.

2016-04-01

In this paper, we used a Venturi tube for generating hydrodynamic cavitation, and in order to obtain the optimum conditions for this to be used in chemical processes, the relationship between the aggressive intensity of the cavitation and the downstream pressure where the cavitation bubbles collapse was investigated. The acoustic power and the luminescence induced by the bubbles collapsing were investigated under various cavitating conditions, and the relationships between these and the cavitation number, which depends on the upstream pressure, the downstream pressure at the throat of the tube and the vapor pressure of the test water, was found. It was shown that the optimum downstream pressure, i.e., the pressure in the region where the bubbles collapse, increased the aggressive intensity by a factor of about 100 compared to atmospheric pressure without the need to increase the input power. Although the optimum downstream pressure varied with the upstream pressure, the cavitation number giving the optimum conditions was constant for all upstream pressures.

Enhancing the aggressive intensity of hydrodynamic cavitation through a Venturi tube by increasing the pressure in the region where the bubbles collapse

Directory of Open Access Journals (Sweden)

H. Soyama

2016-04-01

Full Text Available In this paper, we used a Venturi tube for generating hydrodynamic cavitation, and in order to obtain the optimum conditions for this to be used in chemical processes, the relationship between the aggressive intensity of the cavitation and the downstream pressure where the cavitation bubbles collapse was investigated. The acoustic power and the luminescence induced by the bubbles collapsing were investigated under various cavitating conditions, and the relationships between these and the cavitation number, which depends on the upstream pressure, the downstream pressure at the throat of the tube and the vapor pressure of the test water, was found. It was shown that the optimum downstream pressure, i.e., the pressure in the region where the bubbles collapse, increased the aggressive intensity by a factor of about 100 compared to atmospheric pressure without the need to increase the input power. Although the optimum downstream pressure varied with the upstream pressure, the cavitation number giving the optimum conditions was constant for all upstream pressures.

Treatment of cyanide containing wastewater using cavitation based approach.

Science.gov (United States)

Jawale, Rajashree H; Gogate, Parag R; Pandit, Aniruddha B

2014-07-01

Industrial wastewater streams containing high concentrations of biorefractory materials like cyanides should ideally be treated at source. In the present work, degradation of potassium ferrocyanide (K4Fe(CN)6) as a model pollutant has been investigated using cavitational reactors with possible intensification studies using different approaches. Effect of different operating parameters such as initial concentration, temperature and pH on the extent of degradation using acoustic cavitation has been investigated. For the case of hydrodynamic cavitation, flow characteristics of cavitating device (venturi) have been established initially followed by the effect of inlet pressure and pH on the extent of degradation. Under the optimized set of operating parameters, the addition of hydrogen peroxide (ratio of K4Fe(CN)6:H2O2 varied from 1:1 to 1:30 mol basis) as process intensifying approach has been investigated. The present work has conclusively established that under the set of optimized operating parameters, cavitation can be effectively used for degradation of potassium ferrocyanide. The comparative study of hydrodynamic cavitation and acoustic cavitation suggested that hydrodynamic cavitation is more energy efficient and gives higher degradation as compared to acoustic cavitation for equivalent power/energy dissipation. The present work is the first one to report comparison of cavitation based treatment schemes for degradation of cyanide containing wastewaters. Copyright © 2014 Elsevier B.V. All rights reserved.

Eutrophic water purification efficiency using a combination of hydrodynamic cavitation and ozonation on a pilot scale.

Science.gov (United States)

Li, Wei-Xin; Tang, Chuan-Dong; Wu, Zhi-Lin; Wang, Wei-Min; Zhang, Yu-Feng; Zhao, Yi; Cravotto, Giancarlo

2015-04-01

This paper presents the purification of eutrophic water using a combination of hydrodynamic cavitation (HC) and ozonation (O3) at a continuous flow of 0.8 m(3) h(-1) on a pilot scale. The maximum removal rate of chlorophyll a using O3 alone and the HC/O3 combination was 62.3 and 78.8%, respectively, under optimal conditions, where the ozone utilization efficiency was 64.5 and 94.8% and total energy consumption was 8.89 and 8.25 kWh m(-3), respectively. Thus, the removal rate of chlorophyll a and the ozone utilization efficiency were improved by 26.5% and 46.9%, respectively, by using the combined technique. Meanwhile, total energy consumption was reduced by 7.2%. Turbidity linearly decreased with chlorophyll a removal rate, but no linear relationship exists between the removal of COD or UV254 and chlorophyll a. As expected, the suction-cavitation-assisted O3 exhibited higher energy efficiency than the extrusion-cavitation-assisted O3 and O3 alone methods.

Mineralisation of 2,4-dichlorophenoxyacetic acid by acoustic or hydrodynamic cavitation in conjunction with the advanced Fenton process.

Science.gov (United States)

Bremner, David H; Carlo, Stefano Di; Chakinala, Anand G; Cravotto, Giancarlo

2008-04-01

The mineralisation of 2,4-dichlorophenoxyacetic acid (2,4-D) in the presence of zero-valent iron and hydrogen peroxide (the advanced Fenton process--AFP) whilst being subjected to acoustic or hydrodynamic cavitation is reported. If the reaction is merely stirred then there is 57% removal of TOC whilst on irradiation the figure is 64% although the latter reaction is more rapid. Use of ultrasound alone results in only 11% TOC removal in 60 min of treatment time. Addition of iron powder marginally enhances the extent of degradation but an appreciable increase is observed in the presence of hydrogen peroxide which acts as a source for hydroxyl radicals by Fenton chemistry as well as by dissociation in the presence of ultrasound. The use of hydrodynamic cavitation in conjunction with the advanced Fenton process has also been found to be a useful tool for continuous remediation of water contaminated with 2,4-D. After 20 min of treatment the residual TOC is reduced to 30% and this probably represents the remaining highly recalcitrant small organic molecules.

Hydrodynamic cavitation in Stokes flow of anisotropic fluids

OpenAIRE

Stieger, Tillmann; Agha, Hakam; Schoen, Martin; Mazza, Marco G.; Sengupta, Anupam

2017-01-01

Cavitation, the nucleation of vapour in liquids, is ubiquitous in fluid dynamics, and is often implicated in a myriad of industrial and biomedical applications. Although extensively studied in isotropic liquids, corresponding investigations in anisotropic liquids are largely lacking. Here, by combining liquid crystal microfluidic experiments, nonequilibrium molecular dynamics simulations and theoretical arguments, we report flow-induced cavitation in an anisotropic fluid. The cavitation domai...

Anaerobic Digestion of Cattle Manure Influenced by Swirling Jet Induced Hydrodynamic Cavitation.

Science.gov (United States)

Langone, Michela; Soldano, Mariangela; Fabbri, Claudio; Pirozzi, Francesco; Andreottola, Gianni

2018-04-01

In this work, a modified swirling jet-induced cavitation has been employed for increasing anaerobic digestion efficiency of cattle manure. The hydrodynamic cavitation (HC) treatment improved the organic matter solubilization and the anaerobic biodegradability of cattle manure. The degree of disintegration increased by 5.8, 8.9, and 15.8% after the HC treatment at 6.0, 7.0, and 8.0 bars, respectively. However, the HC treatment at 7.0 bars had better results in terms of methane production. This result may be attributed to the possible formation of toxic and refractory compounds at higher inlet pressures, which could inhibit the methanization process. Further, total Kjeldahl nitrogen content was found to decrease with increasing inlet pressures, as the pH and the turbulent mixing favored the ammonia stripping processes. HC treatment decreased the viscosity of the treated cattle manure, favoring the manure pumping and mixing. Considerations on the energy input due to the HC pre-treatment and the energy output due to the enhanced methane yield have been presented. A positive energy balance can be obtained looking at the improved operational practices in the anaerobic digesters after the implementation of the HC pre-treatment.

Hydrodynamic cavitation as a strategy to enhance the efficiency of lignocellulosic biomass pretreatment.

Science.gov (United States)

Terán Hilares, Ruly; Ramos, Lucas; da Silva, Silvio Silvério; Dragone, Giuliano; Mussatto, Solange I; Santos, Júlio César Dos

2018-06-01

Hydrodynamic cavitation (HC) is a process technology with potential for application in different areas including environmental, food processing, and biofuels production. Although HC is an undesirable phenomenon for hydraulic equipment, the net energy released during this process is enough to accelerate certain chemical reactions. The application of cavitation energy to enhance the efficiency of lignocellulosic biomass pretreatment is an interesting strategy proposed for integration in biorefineries for the production of bio-based products. Moreover, the use of an HC-assisted process was demonstrated as an attractive alternative when compared to other conventional pretreatment technologies. This is not only due to high pretreatment efficiency resulting in high enzymatic digestibility of carbohydrate fraction, but also, by its high energy efficiency, simple configuration, and construction of systems, besides the possibility of using on the large scale. This paper gives an overview regarding HC technology and its potential for application on the pretreatment of lignocellulosic biomass. The parameters affecting this process and the perspectives for future developments in this area are also presented and discussed.

Hydrodynamic cavitation as an efficient pretreatment method for lignocellulosic biomass: A parametric study.

Science.gov (United States)

Terán Hilares, Ruly; de Almeida, Gabriela Faria; Ahmed, Muhammad Ajaz; Antunes, Felipe A F; da Silva, Silvio Silvério; Han, Jong-In; Santos, Júlio César Dos

2017-07-01

Hydrodynamic cavitation (HC), which is a highly destructive force, was employed for pretreatment of sugarcane bagasse (SCB). The efficacy of HC was studied using response surface methodology (RSM) with determining parameters varied: inlet pressure of 1-3bar, temperature of 40-70°C, and alkaline concentration of 0.1-0.3M. At the best condition (3bar, 70°C and 0.3M NaOH), 93.05% and 94.45% of hydrolysis yield of cellulose and hemicellulose, respectively, were obtained within 30min of pretreatment time. Also, pretreatment time higher than 10min had little to do regarding to SCB composition changes using different orifice plates (16 and 27 holes, with corresponding cavitation number of 0.017 and 0.048, respectively), with higher hydrolysis yield observed at 20min of process. Therefore, HC-based approach could lead to a high yield of hydrolysis, as long as a treatment condition was right; it could be so at mild conditions and at short running time. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cavitation simulation on marine propellers

DEFF Research Database (Denmark)

Shin, Keun Woo

Cavitation on marine propellers causes thrust breakdown, noise, vibration and erosion. The increasing demand for high-efficiency propellers makes it difficult to avoid the occurrence of cavitation. Currently, practical analysis of propeller cavitation depends on cavitation tunnel test, empirical...... criteria and inviscid flow method, but a series of model test is costly and the other two methods have low accuracy. Nowadays, computational fluid dynamics by using a viscous flow solver is common for practical industrial applications in many disciplines. Cavitation models in viscous flow solvers have been...... hydrofoils and conventional/highly-skewed propellers are performed with one of three cavitation models proven in 2D analysis. 3D cases also show accuracy and robustness of numerical method in simulating steady and unsteady sheet cavitation on complicated geometries. Hydrodynamic characteristics of cavitation...

Dynamic behaviors of cavitation bubble for the steady cavitating flow

Science.gov (United States)

Cai, Jun; Huai, Xiulan; Li, Xunfeng

2009-12-01

In this paper, by introducing the flow velocity item into the classical Rayleigh-Plesset dynamic equation, a new equation, which does not involve the time term and can describe the motion of cavitation bubble in the steady cavitating flow, has been obtained. By solving the new motion equation using Runge-Kutta fourth order method with adaptive step size control, the dynamic behaviors of cavitation bubble driven by the varying pressure field downstream of a venturi cavitation reactor are numerically simulated. The effects of liquid temperature (corresponding to the saturated vapor pressure of liquid), cavitation number and inlet pressure of venturi on radial motion of bubble and pressure pulse due to the radial motion are analyzed and discussed in detail. Some dynamic behaviors of bubble different from those in previous papers are displayed. In addition, the internal relationship between bubble dynamics and process intensification is also discussed. The simulation results reported in this work reveal the variation laws of cavitation intensity with the flow conditions of liquid, and will lay a foundation for the practical application of hydrodynamic cavitation technology.

Cavitation instabilities and rotordynamic effects in turbopumps and hydroturbines turbopump and inducer cavitation, experiments and design

CERN Document Server

Salvetti, Maria

2017-01-01

The book provides a detailed approach to the physics, fluid dynamics, modeling, experimentation and numerical simulation of cavitation phenomena, with special emphasis on cavitation-induced instabilities and their implications on the design and operation of high performance turbopumps and hydraulic turbines. The first part covers the fundamentals (nucleation, dynamics, thermodynamic effects, erosion) and forms of cavitation (attached cavitation, cloud cavitation, supercavitation, vortex cavitation) relevant to hydraulic turbomachinery, illustrates modern experimental techniques for the characterization, visualization and analysis of cavitating flows, and introduces the main aspects of the hydrodynamic design and performance of axial inducers, centrifugal turbopumps and hydo-turbines. The second part focuses on the theoretical modeling, experimental analysis, and practical control of cavitation-induced fluid-dynamic and rotordynamic instabilities of hydraulic turbomachinery, with special emphasis on cavitating...

Hydrodynamic cavitation to prevent legionella and scaling; Hydrodynamische cavitatie voorkomt legionella en kalk

Energy Technology Data Exchange (ETDEWEB)

Van Baarle, D. (ed.)

2006-03-15

To prevent biofouling, legionella, scaling and corrosion in heat exchangers or cooling systems chemicals are added to the process and the cooling water. An alternative is the use of so-called hydrodynamic cavitation. [Dutch] Om biofouling, kalkaanslag en corrosie tegen te gaan, worden chemicalien aan proces en koelwater toegevoegd. Er is nu ook een chemicalienvrij mechanisch alternatief om legionellavorming, corrosie en kalkafzet tegen te gaan: hydrodynamische cavitatie. Door water in een vortex-stroom te leiden ontstaan er cavitatiekrachten die (legionella)bacterieen doden en CaCO{sub 3} omvormen tot filtreerbare colloiden. Doordat het in het water aanwezige kalk niet neerslaat, verbeter de prestatie van de warmtewisselaars.

On the role of cavitation in particle collection in flotation - A critical review. II

Energy Technology Data Exchange (ETDEWEB)

Zhou, Z.A.; Xu, Z.H.; Finch, J.A.; Masliyah, J.H.; Chow, R.S. [Alberta Research Council, Edmonton, AB (Canada)

2009-04-15

Research in applying hydrodynamic cavitation to recovery of natural resources during the last decade is reviewed. The existence and formation of tiny bubbles or gas nuclei (diameter from microns down to nano sizes) in natural water were verified from both direct and in-direct measurements, providing a foundation for applying hydrodynamic cavitation to flotation systems. The interactions between tiny bubbles and fine particles in aqueous slurry were analysed. Tiny bubbles generated by hydrodynamic cavitation increased contact angle of solids and hence attachment force, bridge fine particles to form aggregates, minimize slime coating, remove oxidation layers on particle surfaces, and in hence reduce reagents consumption. Experiments revealed that the energy dissipation levels for cavity formation in a flowing liquid could be much lower than predicted, depending on the content of dissolved gases, presence of free gas nuclei and design of cavitation tubes. Application of hydrodynamic cavitation to fine and coarse particle flotation, high intensity conditioning, oil agglomeration of fine coal, and oil sands processing has confirmed the role of tiny bubbles formed by cavitation in improving recovery efficiency. Increased flotation kinetics by hydrodynamic cavitation could be attributed to a dual role: some collapsing cavity bubbles serving to break interfacial layers on particle surfaces while other cavity bubbles attaching to those freshly exposed mineral surfaces. The role of water vapor and other gases within cavity bubbles in particle-bubble attachment remains to be explored. Incorporating hydrodynamic cavitation into flotation systems to take advantage of its unique features is expected to develop the next generation of flotation machines.

Study on cavitation effect of mechanical seals with laser-textured porous surface

Science.gov (United States)

Liu, T.; Chen, H. l.; Liu, Y. H.; Wang, Q.; Liu, Z. B.; Hou, D. H.

2012-11-01

Study on the mechanisms underlying generation of hydrodynamic pressure effect associated with laser-textured porous surface on mechanical seal, is the key to seal and lubricant properties. The theory model of mechanical seals with laser-textured porous surface (LES-MS) based on cavitation model was established. The LST-MS was calculated and analyzed by using Fluent software with full cavitation model and non-cavitation model and film thickness was predicted by the dynamic mesh technique. The results indicate that the effect of hydrodynamic pressure and cavitation are the important reasons to generate liquid film opening force on LST-MS; Cavitation effect can enhance hydrodynamic pressure effect of LST-MS; The thickness of liquid film could be well predicted with the method of dynamic mesh technique on Fluent and it becomes larger as the increasing of shaft speed and the decreasing of pressure.

Study on cavitation effect of mechanical seals with laser-textured porous surface

International Nuclear Information System (INIS)

Liu, T; Chen, H l; Liu, Y H; Wang, Q; Liu, Z B; Hou, D H

2012-01-01

Study on the mechanisms underlying generation of hydrodynamic pressure effect associated with laser-textured porous surface on mechanical seal, is the key to seal and lubricant properties. The theory model of mechanical seals with laser-textured porous surface (LES-MS) based on cavitation model was established. The LST-MS was calculated and analyzed by using Fluent software with full cavitation model and non-cavitation model and film thickness was predicted by the dynamic mesh technique. The results indicate that the effect of hydrodynamic pressure and cavitation are the important reasons to generate liquid film opening force on LST-MS; Cavitation effect can enhance hydrodynamic pressure effect of LST-MS; The thickness of liquid film could be well predicted with the method of dynamic mesh technique on Fluent and it becomes larger as the increasing of shaft speed and the decreasing of pressure.

Cavitational synthesis of nanostructured inorganic materials for enhanced heterogeneous catalysis

Science.gov (United States)

Krausz, Ivo Michael

The synthesis of nanostructured inorganic materials by hydrodynamic cavitation processing was investigated. The goal of this work was to develop a general synthesis technique for nanostructured materials with a control over crystallite size in the 1--20 nm range. Materials with crystallite sizes in this range have shown enhanced catalytic activity compared to materials with larger crystallite sizes. Several supported and unsupported inorganic materials were studied to understand the effects of cavitation on crystallite size. Cavitation processing of calcium fluoride resulted in more spherical particles, attached to one another by melted necks. This work produced the first evidence of shock wave heating of nanostructured materials by hydrodynamic cavitation processing. Hydrodynamic cavitation synthesis of various catalytic support materials indicated that their phase composition and purity could be controlled by adjustment of the processing parameters. Zirconia/alumina supports synthesized using hydro-dynamic cavitation and calcined to 1368 K retained a high purity cubic zirconia phase, whereas classically prepared samples showed a phase transformation to monoclinic zirconia. Similarly, the synthesis of alumina resulted in materials with varying Bohmite and Bayerite contents as a function of the process parameters. High temperature calcination resulted in stable alumina supports with varying amounts of delta-, and theta-alumina. Synthesis studies of palladium and silver showed modest variations in crystallite size as a function of cavitation process parameters. Calcination resulted in larger grain materials, indicating a disappearance of intergrain boundaries. Based on these results, a new synthesis method was studied involving controlled agglomeration of small silver crystallites by hydrodynamic cavitation processing, followed by deposition on alumina. The optimal pH, concentration, and processing time for controlling the silver crystallite size in the cavitation

Performance and emission characteristics of a stationary diesel engine fuelled by Schleichera Oleosa Oil Methyl Ester (SOME produced through hydrodynamic cavitation process

Directory of Open Access Journals (Sweden)

Ashok Kumar Yadav

2018-03-01

Full Text Available In this study, the performance and emission characteristics of biodiesel blends of 10, 20, 30 and 50% from Schleichera Oleosa oil based on hydrodynamic cavitation were compared to diesel fuel, and found to be acceptable according to the EN 14214 and ASTM D 6751 standards. The tests have been performed using a single cylinder four stroke diesel engine at different loading condition with the blended fuel at the rated speed of 1500 rpm. SOME (Schleichera Oleosa Oil Methyl Ester blended with diesel in proportions of 10%, 20%, 30% and 50% by volume and pure diesel was used as fuel. Engine performance (specific fuel consumption and brake thermal efficiency and exhaust emission (CO, CO2 and NOx were measured to evaluate the behaviour of the diesel engine running on biodiesel. The results show that the brake thermal efficiency of diesel is higher and brake specific fuel consumption is lower at all loads followed by blends of SOME and diesel. The performance parameter for B10, B20, B30 and B50 were also closer to diesel and the CO emission was found to be lesser than diesel while there was a slight increase in the CO2 and NOx. SOME produced by using hydrodynamic cavitation seems to be efficient, time saving and industrially viable. The experimental results revel that SOME-diesel blends up to 50% (v/v can be used in a diesel engine without modifications. Keywords: Performance, Emission, Diesel engine, Schleichera Oleosa Oil, Biodiesel hydrodynamic cavitation (HC

A parametrical study of disinfection with hydrodynamic cavitation.

Science.gov (United States)

Arrojo, S; Benito, Y; Tarifa, A Martínez

2008-07-01

The physical and chemical conditions generated by cavitation bubbles can be used to destroy microorganisms and disinfect wastewater. The effect of different cavitation chamber designs and diverse operational parameters on the inactivation rate of Escherichia coli have been studied and used to understand the mechanisms involved in cell disruption.

The synthesis of nanostructured, phase pure catalysts by hydrodynamic cavitation

Energy Technology Data Exchange (ETDEWEB)

Moser, W.R.; Sunstrom, J.E.; Marshik-Geurts, B.J. [Worcester Polytechnic Institute, Worcester, MA (United States)

1995-12-01

A new process for the synthesis of advanced catalytic materials based on performing the synthesis under hydrodynamic cavitation conditions has been discovered. This continuous process for catalyst synthesis resulted in the formation of both supported and unsupported catalysts. The advantage of the process over classical methods of synthesis is that it permits the formation of a wide variety of nanostructured catalysts in exceptionally high phase purities. The synthesis of platinum and palladium catalysts supported on alumina and other supports resulted in high dispersions of the noble metals. The synthesis of alpha, beta- and gamma-bismuth molybdates resulted in catalysts having superior phase purities as compared to several other classical methods of synthesis. The beta-bismuth molybdate was synthesized directly onto Cabosil. These studies showed that the particle size of the active component could be varied from a few manometers to much larger grains. The process enabled the synthesis of other complex metal oxides like perovskites as pure phases. The process uses a commercially available Microfluidizer.

Decolourization of Rhodamine B: A swirling jet-induced cavitation combined with NaOCl.

Science.gov (United States)

Mancuso, Giuseppe; Langone, Michela; Laezza, Marco; Andreottola, Gianni

2016-09-01

A hydrodynamic cavitation reactor (Ecowirl) based on swirling jet-induced cavitation has been used in order to allow the degradation of a waste dye aqueous solution (Rhodamine B, RhB). Cavitation generated by Ecowirl reactor was directly compared with cavitation generated by using multiple hole orifice plates. The effects of operating conditions and parameters such as pressure, pH of dye solution, initial concentration of RhB and geometry of the cavitating devices on the degradation rate of RhB were discussed. In similar operative conditions, higher extents of degradation (ED) were obtained using Ecowirl reactor rather than orifice plate. An increase in the ED from 8.6% to 14.7% was observed moving from hole orifice plates to Ecowirl reactor. Intensification in ED of RhB by using hydrodynamic cavitation in presence of NaOCl as additive has been studied. It was found that the decolourization was most efficient for the combination of hydrodynamic cavitation and chemical oxidation as compared to chemical oxidation and hydrodynamic cavitation alone. The value of ED of 83.4% was reached in 37min using Ecowirl combined with NaOCl (4.0mgL(-1)) as compared to the 100min needed by only mixing NaOCl at the same concentration. At last, the energetic consumptions of the cavitation devices have been evaluated. Increasing the ED and reducing the treatment time, Ecowirl reactor resulted to be more energy efficient as compared to hole orifice plates, Venturi and other swirling jet-induced cavitation devices, as reported in literature. Copyright © 2016 Elsevier B.V. All rights reserved.

Some Cavitation Properties of Liquids

Directory of Open Access Journals (Sweden)

K. D. Efremova

2016-01-01

Full Text Available Cavitation properties of liquid must be taken into consideration in the engineering design of hydraulic machines and hydro devices when there is a possibility that in their operation an absolute pressure in the liquid drops below atmospheric one, and for a certain time the liquid is in depression state. Cold boiling, which occurs at a comparatively low temperature under a reduced absolute pressure within or on the surface of the liquid is regarded as hydrostatic cavitation if the liquid is stationary or as hydrodynamic cavitation, if the liquid falls into conditions when in the flow cross-section there is a sharply increasing dynamic pressure and a dropping absolute pressure.In accordance with the theory of cavitation, the first phase of cavitation occurs when the absolute pressure of the degassed liquid drops to the saturated vapour pressure, and the air dissolved in the liquid, leaving the intermolecular space, is converted into micro-bubbles of combined air and becomes a generator of cavitation “nuclei”. A quantitative estimate of the minimum allowable absolute pressure in a real, fully or partially degassed liquid at which a hydrostatic cavitation occurs is of practical interest.Since the pressure of saturated vapour of a liquid is, to a certain extent, related to the forces of intermolecular interaction, it is necessary to have information on the cavitation properties of technical solutions, including air solution in a liquid, as a solute may weaken intermolecular bonds and affect the pressure value of the saturated solvent vapour. In the experiment to carry out vacuum degassing of liquids was used a hydraulic air driven vacuum pump.The paper presents hydrostatic and hydrodynamic degassing liquid processes used in the experiment.The experimental studies of the cavitation properties of technical liquids (sea and distilled water, saturated NaCl solution, and pure glycerol and as a 49/51% solution in water, mineral oil and jet fuel enabled

Large eddy simulation of hydrodynamic cavitation

Science.gov (United States)

Bhatt, Mrugank; Mahesh, Krishnan

2017-11-01

Large eddy simulation is used to study sheet to cloud cavitation over a wedge. The mixture of water and water vapor is represented using a homogeneous mixture model. Compressible Navier-Stokes equations for mixture quantities along with transport equation for vapor mass fraction employing finite rate mass transfer between the two phases, are solved using the numerical method of Gnanaskandan and Mahesh. The method is implemented on unstructured grid with parallel MPI capabilities. Flow over a wedge is simulated at Re = 200 , 000 and the performance of the homogeneous mixture model is analyzed in predicting different regimes of sheet to cloud cavitation; namely, incipient, transitory and periodic, as observed in the experimental investigation of Harish et al.. This work is supported by the Office of Naval Research.

Simulations of Steady Cavitating Flow in a Small Francis Turbine

Directory of Open Access Journals (Sweden)

Ahmed Laouari

2016-01-01

Full Text Available The turbulent flow through a small horizontal Francis turbine is solved by means of Ansys-CFX at different operating points, with the determination of the hydrodynamic performance and the best efficiency point. The flow structures at different regimes reveal a large flow eddy in the runner and a swirl in the draft tube. The use of the mixture model for the cavity/liquid two-phase flow allowed studying the influence of cavitation on the hydrodynamic performance and revealed cavitation pockets near the trailing edge of the runner and a cavitation vortex rope in the draft tube. By maintaining a constant dimensionless head and a distributor vane opening while gradually increasing the cavitation number, the output power and efficiency reached a critical point and then had begun to stabilize. The cavitation number corresponding to the safety margin of cavitation is also predicted for this hydraulic turbine.

Numerical investigation of cavitation flow in journal bearing geometry

OpenAIRE

Stücke P.; Schmidt M.; Riedel M.

2013-01-01

The appearance of cavitation is still a problem in technical and industrial applications. Especially in automotive internal combustion engines, hydrodynamic journal bearings are used due to their favourable wearing quality and operating characteristics. Cavitation flows inside the bearings reduces the load capacity and leads to a risk of material damages. Therefore an understanding of the complex flow phenomena inside the bearing is necessary for the design development of hydrodynamic journal...

Application of hydrodynamic cavitation in ballast water treatment.

Science.gov (United States)

Cvetković, Martina; Kompare, Boris; Klemenčič, Aleksandra Krivograd

2015-05-01

Ballast water is, together with hull fouling and aquaculture, considered the most important factor of the worldwide transfer of invasive non-indigenous organisms in aquatic ecosystems and the most important factor in European Union. With the aim of preventing and halting the spread of the transfer of invasive organisms in aquatic ecosystems and also in accordance with IMO's International Convention for the Control and Management of Ships Ballast Water and Sediments, the systems for ballast water treatment, whose work includes, e.g. chemical treatment, ozonation and filtration, are used. Although hydrodynamic cavitation (HC) is used in many different areas, such as science and engineering, implied acoustics, biomedicine, botany, chemistry and hydraulics, the application of HC in ballast water treatment area remains insufficiently researched. This paper presents the first literature review that studies lab- and large-scale setups for ballast water treatment together with the type-approved systems currently available on the market that use HC as a step in their operation. This paper deals with the possible advantages and disadvantages of such systems, as well as their influence on the crew and marine environment. It also analyses perspectives on the further development and application of HC in ballast water treatment.

Research on axial thrust of the waterjet pump based on CFD under cavitation conditions

International Nuclear Information System (INIS)

Shen, Z H; Pan, Z Y

2015-01-01

Based on RANS equations, performance of a contra-rotating axial-flow waterjet pump without hydrodynamic cavitation state had been obtained combined with shear stress transport turbulence model. Its cavitation hydrodynamic performance was calculated and analysed with mixture homogeneous flow cavitation model based on Rayleigh-Plesset equations. The results shows that the cavitation causes axial thrust of waterjet pump to drop. Furthermore, axial thrust and head cavitation characteristic curve is similar. However, the drop point of the axial thrust is postponed by 5.1% comparing with one of head, and the critical point of the axial thrust is postponed by 2.6%

Research on axial thrust of the waterjet pump based on CFD under cavitation conditions

Science.gov (United States)

Shen, Z. H.; Pan, Z. Y.

2015-01-01

Based on RANS equations, performance of a contra-rotating axial-flow waterjet pump without hydrodynamic cavitation state had been obtained combined with shear stress transport turbulence model. Its cavitation hydrodynamic performance was calculated and analysed with mixture homogeneous flow cavitation model based on Rayleigh-Plesset equations. The results shows that the cavitation causes axial thrust of waterjet pump to drop. Furthermore, axial thrust and head cavitation characteristic curve is similar. However, the drop point of the axial thrust is postponed by 5.1% comparing with one of head, and the critical point of the axial thrust is postponed by 2.6%.

Design of an Efficient Turbulent Micro-Mixer for Protein Folding Experiments

Science.gov (United States)

Inguva, Venkatesh; Perot, Blair

2015-11-01

Protein folding studies require the development of micro-mixers that require less sample, mix at faster rates, and still provide a high signal to noise ratio. Chaotic to marginally turbulent micro-mixers are promising candidates for this application. In this study, various turbulence and unsteadiness generation concepts are explored that avoid cavitation. The mixing enhancements include flow turning regions, flow splitters, and vortex shedding. The relative effectiveness of these different approaches for rapid micro-mixing is discussed. Simulations found that flow turning regions provided the best mixing profile. Experimental validation of the optimal design is verified through laser confocal microscopy experiments. This work is support by the National Science Foundation.

Biodiesel Production from Waste Cooking Oil Using Hydrodinamic Cavitation

OpenAIRE

Muhammad Supardan; Satriana Satriana; Mahlinda Mahlinda

2013-01-01

The aim of this research was to study biodiesel production from low cost feedstock of waste cooking oil (WCO) using hydrodynamic cavitation apparatus. A two-step processes esterification process and transesterification process using hydrodynamic cavitation for the production of biodiesel from WCO is presented. The first step is acid-catalyzed esteri-fication process for reducing free fatty acid (FFA) content of WCO and followed by base-catalyzed transesterification process for converting WCO ...

An Experimental Investigation of Acoustic Cavitation in Gaseous Liquids

Science.gov (United States)

1990-11-08

successfully to represent cavities formed by rotating propellers and, more 3 generally, by hydrodynamic cavitation . No further improvements to Rayleigh’s theory...motivated by the increasing concern over the rapid deterioration of ship propellers. This deterioration was caused by what is now known as hydrodynamic ... cavitation . Rayleigh’s equation can be obtained by equating the 0 power at infinity and the time rate of change of the kinetic energy in an incompressible

Experimental investigation of cavitation induced air release

Science.gov (United States)

Kowalski, Karoline; Pollak, Stefan; Hussong, Jeanette

Variations in cross-sectional areas may lead to pressure drops below a critical value, such that cavitation and air release are provoked in hydraulic systems. Due to a relatively slow dissolution of gas bubbles, the performance of hydraulic systems will be affected on long time scales by the gas phase. Therefore predictions of air production rates are desirable to describe the system characteristics. Existing investigations on generic geometries such as micro-orifice flows show an outgassing process due to hydrodynamic cavitation which takes place on time scales far shorter than diffusion processes. The aim of the present investigation is to find a correlation between global, hydrodynamic flow characteristics and cavitation induced undissolved gas fractions generated behind generic flow constrictions such as an orifice or venturi tube. Experimental investigations are realised in a cavitation channel that enables an independent adjustment of the pressure level upstream and downstream of the orifice. Released air fractions are determined by means of shadowgraphy imaging. First results indicate that an increased cavitation activity leads to a rapid increase in undissolved gas volume only in the choking regime. The frequency distribution of generated gas bubble size seems to depend only indirectly on the cavitation intensity driven by an increase of downstream coalescence events due to a more densely populated bubbly flow.

Cavitating behaviour analysis of Darrieus-type cross flow water turbines

International Nuclear Information System (INIS)

Aumelas, V; Pellone, C; MaItre, T

2010-01-01

The aim of this paper is to study the cavitating behaviour of bare Darrieus-type turbines. For that, the RANS code CAVKA, has been used. Under non-cavitating conditions, the power coefficient and the thrusts calculated with CAVKA are compared to experimental values obtained in the LEGI hydrodynamic tunnel. Under cavitating conditions, for several cavitation numbers, the numerical power coefficients and vapour structures are compared to experimental ones. Different blade profiles and camber lines are also studied for non-cavitating and cavitating conditions.

Hydrodynamic cavitation in microsystems. II. Simulations and optical observations

Science.gov (United States)

Medrano, M.; Pellone, C.; Zermatten, P. J.; Ayela, F.

2012-04-01

Numerical calculations in the single liquid phase and optical observations in the two-phase cavitating flow regime have been performed on microdiaphragms and microventuris fed with deionized water. Simulations have confirmed the influence of the shape of the shrinkage upon the contraction of the jet, and so on the localisation of possible cavitating area downstream. Observations of cavitating flow patterns through hybrid silicon-pyrex microdevices have been performed either via a laser excitation with a pulse duration of 6 ns, or with the help of a high-speed camera. Recorded snapshots and movies are presented. Concerning microdiaphragms, it is confirmed that very high shear rates downstream the diaphragms are the cause of bubbly flows. Concerning microventuris, a gaseous cavity forms on a boundary downstream the throat. As a consequence of a microsystem instability, the cavity displays a high frequency pulsation. Low values Strouhal numbers are associated to such a sheet cavitation. Moreover, when the intensity of the cavitating flow is reduced, there is a mismatch between the frequency of the pulsation of the cavity and the frequency of shedded clouds downstream the channel. That may be the consequence of viscous effects limiting the impingement of a re-entrant liquid jet on the attached cavity.

Monitoring of full-scale hydrodynamic cavitation pretreatment in agricultural biogas plant.

Science.gov (United States)

Garuti, Mirco; Langone, Michela; Fabbri, Claudio; Piccinini, Sergio

2018-01-01

The implementation of hydrodynamic cavitation (HC) pretreatment for enhancing the methane potential from agricultural biomasses was evaluated in a full scale agricultural biogas plant, with molasses and corn meal as a supplementary energy source. HC batch tests were run to investigate the influence on methane production, particle size and viscosity of specific energy input. 470kJ/kgTS was chosen for the full-scale implementation. Nearly 6-months of operational data showed that the HC pretreatment maximized the specific methane production of about 10%, allowing the biogas plant to get out of the fluctuating markets of supplementary energy sources and to reduce the methane emissions. HC influenced viscosity and particle size of digestate, contributing to reduce the energy demand for mixing, heating and pumping. In the light of the obtained results the HC process appears to be an attractive and energetically promising alternative to other pretreatments for the degradation of biomasses in biogas plant. Copyright © 2017 Elsevier Ltd. All rights reserved.

Numerical simulation of the cavitation's hydrodynamic excitement

International Nuclear Information System (INIS)

Hassis, H.; Dueymes, E.; Lauro, J.F.

1993-01-01

First, we study the motion, the velocity, the phases plane and the acoustic sources associated to a spherical bubble in a compressible or incompressible medium. The bubble can be excited by periodic or random excitements. We study the parameters which influence their behaviour: periodicity or not of motion, implosion and explosion or oscillation of bubble. We take into account this behaviour in a model of cavitation: it is a numerical simulation using population of bubbles which are with positions (in the cavitation volume) and sizes are random. These bubbles are excited by a random excitement: a model of turbulent flow or implosion and explosion of bubble. (author)

Experimental investigation of cavitation induced air release

Directory of Open Access Journals (Sweden)

Kowalski Karoline

2017-01-01

Full Text Available Variations in cross-sectional areas may lead to pressure drops below a critical value, such that cavitation and air release are provoked in hydraulic systems. Due to a relatively slow dissolution of gas bubbles, the performance of hydraulic systems will be affected on long time scales by the gas phase. Therefore predictions of air production rates are desirable to describe the system characteristics. Existing investigations on generic geometries such as micro-orifice flows show an outgassing process due to hydrodynamic cavitation which takes place on time scales far shorter than diffusion processes. The aim of the present investigation is to find a correlation between global, hydrodynamic flow characteristics and cavitation induced undissolved gas fractions generated behind generic flow constrictions such as an orifice or venturi tube. Experimental investigations are realised in a cavitation channel that enables an independent adjustment of the pressure level upstream and downstream of the orifice. Released air fractions are determined by means of shadowgraphy imaging. First results indicate that an increased cavitation activity leads to a rapid increase in undissolved gas volume only in the choking regime. The frequency distribution of generated gas bubble size seems to depend only indirectly on the cavitation intensity driven by an increase of downstream coalescence events due to a more densely populated bubbly flow.

Observations and Measurements on Unsteady Cloud Cavitation Flow Structures

International Nuclear Information System (INIS)

Gu, L X; Yan, G J; Huang, B

2015-01-01

The objectives of this paper are to investigate the unsteady structures and hydrodynamics of cavitating flows. Experimental results are presented for a Clark-Y hydrofoil, which is fixed at α=0°, 5° and 8°. The high-speed video camera and Particle Image Velocimetry (PIV) are applied to investigate the transient flow structures. The dynamic measurement system is used to record the dynamic characteristics. The cloud cavitation exhibits noticeable unsteady characteristics. For the case of α=0°, there exit strong interactions between the attached cavity and the re-entrant flow. While for the case of α=8°, the re-entrant flow is relatively thin and the interaction between the cavity and re-entrant flow is limited. The results also present that the periodic collapse and shedding of the large-scale cloud cavitation, which leads to substantial increase of turbulent velocity fluctuations in the cavity region. Experimental evidence indicates that the hydrodynamics are clearly affected by the cavitating flow structures, the amplitude of load fluctuation are much higher for the cloud cavitating cases. (paper)

Observations and Measurements on Unsteady Cloud Cavitation Flow Structures

Science.gov (United States)

Gu, L. X.; Yan, G. J.; Huang, B.

2015-12-01

The objectives of this paper are to investigate the unsteady structures and hydrodynamics of cavitating flows. Experimental results are presented for a Clark-Y hydrofoil, which is fixed at α=0°, 5° and 8°. The high-speed video camera and Particle Image Velocimetry (PIV) are applied to investigate the transient flow structures. The dynamic measurement system is used to record the dynamic characteristics. The cloud cavitation exhibits noticeable unsteady characteristics. For the case of α=0°, there exit strong interactions between the attached cavity and the re-entrant flow. While for the case of α=8°, the re-entrant flow is relatively thin and the interaction between the cavity and re-entrant flow is limited. The results also present that the periodic collapse and shedding of the large-scale cloud cavitation, which leads to substantial increase of turbulent velocity fluctuations in the cavity region. Experimental evidence indicates that the hydrodynamics are clearly affected by the cavitating flow structures, the amplitude of load fluctuation are much higher for the cloud cavitating cases.

Hydrodynamic cavitation as a novel pretreatment approach for bioethanol production from reed.

Science.gov (United States)

Kim, Ilgook; Lee, Ilgyu; Jeon, Seok Hwan; Hwang, Taewoon; Han, Jong-In

2015-09-01

In this study, hydrodynamic cavitation (HC) was employed as a physical means to improve alkaline pretreatment of reed. The HC-assisted alkaline pretreatment was undertaken to evaluate the influence of NaOH concentration (1-5%), solid-to-liquid ratio (5-15%), and reaction time (20-60 min) on glucose yield. The optimal condition was found to be 3.0% NaOH at solid-to-liquid (S/L) ratio of 11.8% for 41.1 min, which resulted in the maximum glucose yield of 326.5 g/kg biomass. Furthermore, simultaneous saccharification and fermentation (SSF) was conducted to assess the ethanol production. An ethanol concentration of 25.9 g/L and ethanol yield of 90% were achieved using batch SSF. These results clearly demonstrated HC system can be indeed a promising pretreatment tool for lignocellulosic bioethanol production. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of hydrodynamic cavitation on zooplankton: A tool for disinfection

Digital Repository Service at National Institute of Oceanography (India)

Sawant, S.S.; Anil, A.C.; Venkat, K.; Gaonkar, C.; Kolwalkar, J.; Khandeparker, L.; Desai, D.V.; Mahulkar, A.V.; Ranade, V.V.; Pandit, A.B.

by individual oscillating cavity, cell wall strength and geometrical and operating parameters of cavitation device. Theoretical model for quantifying the cavitationally generated turbulent shear and extent of microbial disinfection has been developed...

Технология интенсификации добычи нефти и повышения нефтеотдачи пласта с применением эмульсионных композиций

OpenAIRE

Карсеко, К. С.

2016-01-01

Objects of the research are hydrodynamic mixers to obtain emulsions, based on cavitation, which can be applied for enhanced oil recovery. The purpose of the work is development of design of the mixer to obtain water-in-oil and acid-in-oil emulsions. In the process of the research carried out design studies and model tests of various types of these devices. Design of the mixer with no moving elements in the anticorrosion performance is the result of the research.

Cavitations synthesis of carbon nanostructures

International Nuclear Information System (INIS)

Voropaev, S

2011-01-01

Originally an idea of diamonds production by hydrodynamical cavitation was presented by academician E.M. Galimov. He supposed the possibility of nature diamonds formation at fast magma flowing in kimberlitic pipes during bubbles collapse. This hypothesis assumes a number of processes, which were not under consideration until now. It concerns cavitation under high pressure, growth and stability of the gas- and vapors bubbles, their evolution, and corresponding physical- and chemical processes inside. Experimental setup to reproduce the high pressure and temperature reaction centers by means of the cavitation following the above idea was created. A few crystalline nanocarbon forms were successfully recovered after treatment of benzene (C 6 H 6 ).

Simultaneous treatment (cell disruption and lipid extraction) of wet microalgae using hydrodynamic cavitation for enhancing the lipid yield.

Science.gov (United States)

Lee, Ilgyu; Han, Jong-In

2015-06-01

Simultaneous treatment (combining with cell disruption and lipid extraction) using hydrodynamic cavitation (HC) was applied to Nannochloropsis salina to demonstrate a simple and integrated way to produce oil from wet microalgae. A high lipid yield from the HC (25.9-99.0%) was observed compared with autoclave (16.2-66.5%) and ultrasonication (5.4-26.9%) in terms of the specific energy input (500-10,000 kJ/kg). The optimal conditions for the simultaneous treatment were established using a statistical approach. The efficiency of the simultaneous method was also demonstrated by comparing each separate treatment. The maximum lipid yield (predicted: 45.9% and experimental: 45.5%) was obtained using 0.89% sulfuric acid with a cavitation number of 1.17 for a reaction time of 25.05 min via response surface methodology. Considering its comparable extractability, energy-efficiency, and potential for scale-up, HC may be a promising method to achieve industrial-scale microalgae operation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Transition of cavitating flow to supercavitation within Venturi nozzle – hysteresis investigation

OpenAIRE

Jiří Kozák; Pavel Rudolf; Rostislav Huzlík; Martin Hudec; Radomír Chovanec; Ondřej Urban; Blahoslav Maršálek; Eliška Maršálková; František Pochylý; David Štefan

2017-01-01

Cavitation is usually considered as undesirable phenomena. On the other hand, it can be utilized in many applications. One of the technical applications is using cavitation in water treatment, where hydrodynamic cavitation seems to be effective way how to reduce cyanobacteria within large bulks of water. The main scope of this paper is investigation of the cavitation within Venturi nozzle during the transition from fully developed cavitation to supercavitation regime and vice versa. Dynamics ...

Hydrodynamic cavitation-assisted alkaline pretreatment as a new approach for sugarcane bagasse biorefineries.

Science.gov (United States)

Terán Hilares, Ruly; Dos Santos, Júlio César; Ahmed, Muhammad Ajaz; Jeon, Seok Hwan; da Silva, Silvio Silvério; Han, Jong-In

2016-08-01

Hydrodynamic cavitation (HC) was employed in order to improve the efficiency of alkaline pretreatment of sugarcane bagasse (SCB). Response surface methodology (RSM) was used to optimize pretreatment parameters: NaOH concentration (0.1-0.5M), solid/liquid ratio (S/L, 3-10%) and HC time (15-45min), in terms of glucan content, lignin removal and enzymatic digestibility. Under an optimal HC condition (0.48M of NaOH, 4.27% of S/L ratio and 44.48min), 52.1% of glucan content, 60.4% of lignin removal and 97.2% of enzymatic digestibility were achieved. Moreover, enzymatic hydrolysis of the pretreated SCB resulted in a yield 82% and 30% higher than the untreated and alkaline-treated controls, respectively. HC was found to be a potent and promising approach to pretreat lignocellulosic biomass. Copyright © 2016 Elsevier Ltd. All rights reserved.

Can Cavitation Be Anticipated?

Energy Technology Data Exchange (ETDEWEB)

Allgood, G.O.; Dress, W.B.; Hylton, J.O.; Kercel, S.W.

1999-04-25

The major problem with cavitation in pumps and hydraulic systems is that there is no effective (conventional) method for detecting or predicting its inception. The traditional method of recognizing cavitation in a pump is to declare the event occurring when the total head drops by some arbitrary value (typically 3%) in response to a pressure reduction at the pump inlet. However, the device is already seriously cavitating when this happens. What is actually needed is a practical method to detect impending rather than incipient cavitation. Whereas the detection of incipient cavitation requires the detection of features just after cavitation starts, the anticipation of cavitation requires the detection and identification of precursor features just before it begins. Two recent advances that make this detection possible. The first is acoustic sensors with a bandwidth of 1 MHz and a dynamic range of 80 dB that preserve the fine details of the features when subjected to coarse vibrations. The second is the application of Bayesian parameter estimation which makes it possible to separate weak signals, such as those present in cavitation precursors, from strong signals, such as pump vibration. Bayesian parameter estimation derives a model based on cavitation hydrodynamics and produces a figure of merit of how well it fits the acquired data. Applying this model to an anticipatory engine should lead to a reliable method of anticipating cavitation before it occurs. This paper reports the findings of precursor features using high-performance sensors and Bayesian analysis of weak acoustic emissions in the 100-1000kHz band from an experimental flow loop.

Numerical investigation of the effects of geometric parameters on transverse motion with slanted-groove micro-mixers

Energy Technology Data Exchange (ETDEWEB)

Baik, Seung Joo; Cho, Jae Yong; Choi, Se Bin; Lee, Joon Sang [School of Mechanical Engineering, Yonsei University, Seoul (Korea, Republic of)

2016-08-15

We investigated hydrodynamic phenomena inside several passive microfluidic mixers using a Lattice Boltzmann method (LBM) based on particle mesoscopic kinetic equations. Mixing processes were simulated in a Slanted grooved micro-mixer (SGM), a Staggered herringbone grooved micro-mixer (SHM), and a Bi-layered staggered herringbone grooved micro-mixer (BSHM). Then, the effects of six geometric mixer parameters (i.e., groove height to channel height ratio, groove width to groove pitch length ratio, groove pitch to groove height ratio, groove intersection angle, herringbone groove asymmetric ratio and bi-layered groove asymmetric ratio) on mixing were investigated using computed cross-flow velocity and helicity density distributions in the flow cross-section. We demonstrated that helicity density provides sufficient information to analyze micro helical motion within a micro-mixer, allowing for micro-mixer design optimization.

Biodiesel production process intensification using a rotor-stator type generator of hydrodynamic cavitation.

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Crudo, Daniele; Bosco, Valentina; Cavaglià, Giuliano; Grillo, Giorgio; Mantegna, Stefano; Cravotto, Giancarlo

2016-11-01

Triglyceride transesterification for biodiesel production is a model reaction which is used to compare the conversion efficiency, yield, reaction time, energy consumption, scalability and cost estimation of different reactor technology and energy source. This work describes an efficient, fast and cost-effective procedure for biodiesel preparation using a rotating generator of hydrodynamic cavitation (HC). The base-catalyzed transesterification (methanol/sodium hydroxide) has been carried out using refined and bleached palm oil and waste vegetable cooking oil. The novel HC unit is a continuous rotor-stator type reactor in which reagents are directly fed into the controlled cavitation chamber. The high-speed rotation of the reactor creates micron-sized droplets of the immiscible reacting mixture leading to outstanding mass and heat transfer and enhancing the kinetics of the transesterification reaction which completes much more quickly than traditional methods. All the biodiesel samples obtained respect the ASTM standard and present fatty acid methyl ester contents of >99% m/m in both feedstocks. The electrical energy consumption of the HC reactor is 0.030kWh per L of produced crude biodiesel, making this innovative technology really quite competitive. The reactor can be easily scaled-up, from producing a few hundred to thousands of liters of biodiesel per hour while avoiding the risk of orifices clogging with oil impurities, which may occur in conventional HC reactors. Furthermore it requires minimal installation space due to its compact design, which enhances overall security. Copyright © 2016 Elsevier B.V. All rights reserved.

Highly effective degradation of selected groups of organic compounds by cavitation based AOPs under basic pH conditions.

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Gągol, Michał; Przyjazny, Andrzej; Boczkaj, Grzegorz

2018-07-01

Cavitation has become on the most often applied methods in a number of industrial technologies. In the case of oxidation of organic pollutants occurring in the aqueous medium, cavitation forms the basis of numerous advanced oxidation processes (AOPs). This paper presents the results of investigations on the efficiency of oxidation of the following groups of organic compounds: organosulfur, nitro derivatives of benzene, BTEX, and phenol and its derivatives in a basic model effluent using hydrodynamic and acoustic cavitation combined with external oxidants, i.e., hydrogen peroxide, ozone and peroxone. The studies revealed that the combination of cavitation with additional oxidants allows 100% oxidation of the investigated model compounds. However, individual treatments differed with respect to the rate of degradation. Hydrodynamic cavitation aided by peroxone was found to be the most effective treatment (100% oxidation of all the investigated compounds in 60 min). When using hydrodynamic and acoustic cavitation alone, the effectiveness of oxidation was diversified. Under these conditions, nitro derivatives of benzene and phenol and its derivatives were found to be resistant to oxidation. In addition, hydrodynamic cavitation was found to be more effective in degradation of model compounds than acoustic cavitation. The results of investigations presented in this paper compare favorably with the investigations on degradation of organic contaminants using AOPs under conditions of basic pH published thus far. Copyright © 2018 Elsevier B.V. All rights reserved.

Degradation of carbamazepine using hydrodynamic cavitation combined with advanced oxidation processes.

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Thanekar, Pooja; Panda, Mihir; Gogate, Parag R

2018-01-01

Degradation of carbamazepine (CBZ), a widely detected recalcitrant pharmaceutical in sewage treatment plant (STP) effluent, has been studied in the present work using combination of hydrodynamic cavitation (HC) and advanced oxidation processes (AOPs). Due to its recalcitrant nature, it cannot be removed effectively by the conventional wastewater treatment plants (WWTPs) which make CBZ a pharmaceutical of very high environmental relevance and impact as well as stressing the need for developing new treatment schemes. In the present study, the effect of inlet pressure (3-5bar) and operating pH (3-11) on the extent of degradation have been initially studied with an objective of maximizing the degradation using HC alone. The established optimum conditions as pressure of 4bar and pH of 4 resulted in maximum degradation of CBZ as 38.7%. The combined approaches of HC with ultraviolet irradiation (HC+UV), hydrogen peroxide (HC+H 2 O 2 ), ozone (HC+O 3 ) as well as combination of HC, H 2 O 2 and O 3 (HC+H 2 O 2 +O 3 ) have been investigated under optimized pressure and operating pH. It was observed that a significant increase in the extent of degradation is obtained for the combined operations of HC+H 2 O 2 +O 3 , HC+O 3 , HC+H 2 O 2 , and HC+UV with the actual extent of degradation being 100%, 91.4%, 58.3% and 52.9% respectively. Kinetic analysis revealed that degradation of CBZ fitted into first order kinetics model for all the approaches. The processes were also compared on the basis of cavitational yield and also in terms of total treatment cost. Overall, it has been demonstrated that combined process of HC, H 2 O 2 and O 3 can be effectively used for treatment of wastewater containing CBZ. Copyright © 2017 Elsevier B.V. All rights reserved.

Degradation of reactive blue 13 using hydrodynamic cavitation: Effect of geometrical parameters and different oxidizing additives.

Science.gov (United States)

Rajoriya, Sunil; Bargole, Swapnil; Saharan, Virendra Kumar

2017-07-01

Decolorization of reactive blue 13 (RB13), a sulphonated azo dye, was investigated using hydrodynamic cavitation (HC). The aim of research article is to check the influence of geometrical parameters (total flow area, the ratio of throat perimeter to its cross-sectional area, throat shape and size, etc.) and configuration of the cavitating devices on decolorization of RB13 in aqueous solution. For this purpose, eight cavitating devices i.e. Circular and slit venturi, and six orifice plates having different flow area and perimeter were used in the present work. Initially, the effects of various operating parameters such as solution pH, initial dye concentration, operating inlet pressure and cavitation number on the decolorization of RB13 have been investigated, and the optimum operating conditions were found. Kinetic analysis revealed that the decolorization and mineralization of RB13 using HC followed first order reaction kinetics. Almost 47% decolorization of RB13 was achieved using only HC with slit venturi as a cavitating device at an optimum inlet pressure of 0.4MPa and pH of the solution as 2.0. It has been found that in case of orifice plates, higher decolorization rate of 4×10 -3 min -1 was achieved using orifice plate 2 (OP2) which is having higher flow area and perimeter (α=2.28). The effect of process intensifying agents (hydrogen peroxide and ferrous sulphate) and different gaseous additives (oxygen and ozone) on the extent of decolorization of RB13 were also examined. Almost 66% decolorization of RB13 was achieved using HC combined with 2Lmin -1 of oxygen and in combination with ferrous sulphate (1:3). Nearly 91% decolorization was achieved using HC combined with H 2 O 2 at an optimum molar ratio (dye:H 2 O 2 ) of 1:20 while almost complete decolorization was observed in 15min using a combination of HC and ozone at 3gh -1 ozone feed rate. Maximum 72% TOC was removed using HC coupled with 3gh -1 ozone feed rate. Copyright © 2017 Elsevier B.V. All

Experimental evidence of temperature gradients in cavitating microflows seeded with thermosensitive nanoprobes

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Ayela, Frédéric; Medrano-Muñoz, Manuel; Amans, David; Dujardin, Christophe; Brichart, Thomas; Martini, Matteo; Tillement, Olivier; Ledoux, Gilles

2013-10-01

Thermosensitive fluorescent nanoparticles seeded in deionized water combined with confocal microscopy enables thermal mapping over three dimensions of the liquid phase flowing through a microchannel interrupted by a microdiaphragm. This experiment reveals the presence of a strong thermal gradient up to ˜105 K/m only when hydrodynamic cavitation is present. Here hydrodynamic cavitation is the consequence of high shear rates downstream in the diaphragm. This temperature gradient is located in vortical structures associated with eddies in the shear layers. We attribute such overheating to the dissipation involved by the cavitating flow regime. Accordingly, we demonstrate that the microsizes of the device enhance the intensity of the thermal gap.

Cavitation erosion - scale effect and model investigations

Science.gov (United States)

Geiger, F.; Rutschmann, P.

2015-12-01

The experimental works presented in here contribute to the clarification of erosive effects of hydrodynamic cavitation. Comprehensive cavitation erosion test series were conducted for transient cloud cavitation in the shear layer of prismatic bodies. The erosion pattern and erosion rates were determined with a mineral based volume loss technique and with a metal based pit count system competitively. The results clarified the underlying scale effects and revealed a strong non-linear material dependency, which indicated significantly different damage processes for both material types. Furthermore, the size and dynamics of the cavitation clouds have been assessed by optical detection. The fluctuations of the cloud sizes showed a maximum value for those cavitation numbers related to maximum erosive aggressiveness. The finding suggests the suitability of a model approach which relates the erosion process to cavitation cloud dynamics. An enhanced experimental setup is projected to further clarify these issues.

An unsteady microfluidic T-form mixer perturbed by hydrodynamic pressure

International Nuclear Information System (INIS)

Ma Yanbao; Sun, Chien-Pin; Fields, Michael; Ho, Chih-Ming; Li Yang; Haake, David A; Churchill, Bernard M

2008-01-01

An unsteady microfluidic T-form mixer driven by pressure disturbances was designed and investigated. The performance of the mixer was examined both through numerical simulation and experimentation. Linear Stokes equations were used for these low Reynolds number flows. Unsteady mixing in a micro-channel of two aqueous solutions differing in concentrations of chemical species was described using a convection-dominated diffusion equation. The task was greatly simplified by employing linear superimposition of a velocity field for solving a scalar species concentration equation. Low-order-based numerical codes were found not to be suitable for simulation of a convection-dominated mixing process due to erroneous computational dissipation. The convection-dominated diffusion problem was addressed by designing a numerical algorithm with high numerical accuracy and computational-cost effectiveness. This numerical scheme was validated by examining a test case prior to being applied to the mixing simulation. Parametric analysis was performed using this newly developed numerical algorithm to determine the best mixing conditions. Numerical simulation identified the best mixing condition to have a Strouhal number (St) of 0.42. For a T-junction mixer (with channel width = 196 µm), about 75% mixing can be finished within a mixing distance of less than 3 mm (i.e. 15 channel width) at St = 0.42 for flow with a Reynolds number less than 0.24. Numerical results were validated experimentally by mixing two aqueous solutions containing yellow and blue dyes. Visualization of the flow field under the microscope revealed a high level of agreement between numerical simulation and experimental results

Analysis of hydrodynamical pressure of cavitation flow on the boundary surface

International Nuclear Information System (INIS)

Volin, V.E.; Donchenko, E.G.; Chepajkin, G.A.; Lunatsi, E.D.; Chernishov, P.S.; Shvartser, A.L.

1976-01-01

This paper substantiates the necessity of receiving test data for creation of the methods of cavitation impact impulses on the hydraulic machines and hydraulic structures. The paper describes the methodics of experimental research of intensity of impact cavitation impulses on the elements of flowing canals at different regimes of operation; the method of determining the expected erosion in flowing canals; the method of measuring the parameters of cavitation impacts on the wall of flowing canals with the use of easily damaged varnished coverings, piezo-electric pressure transducers and amplitude and spectrum analysators. The form of a separate cavitation impact is established, the sequence of impact frequency is determined and the amplitude spectra of impacts are obtained. The analysis of test results is given

Hybrid treatment strategies for 2,4,6-trichlorophenol degradation based on combination of hydrodynamic cavitation and AOPs.

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Barik, Arati J; Gogate, Parag R

2018-01-01

Utilization of hybrid treatment schemes involving advanced oxidation processes and hydrodynamic cavitation in the wastewater treatment forms the prime focus of the present work. The initial phase of the work includes analysis of recent literature relating to the performance of combined approach based on hydrodynamic cavitation (HC) for degradation of different pollutants followed by a detailed investigation into degradation of 2,4,6-trichlorophenol (2,4,6-TCP). The degradation of the priority pollutant, 2,4,6-TCP, using combination of HC based on slit-venturi used as the cavitating device, ozone and H 2 O 2 has been investigated. The effect of operating pressure (2-5bar) and initial pH (3-11) have been investigated for the degradation using only HC. The degradation using only ozone (100-400mg/h) and only H 2 O 2 has also been studied. The efficacy of the combined operation of HC+O 3 at different ozone flow rates (100-400mg/h) and the combined operation of HC+H 2 O 2 at different loadings of H 2 O 2 (2,4,6-TCP:H 2 O 2 as 1:1-1:7) have been subsequently investigated. The degradation efficacy has also been established for the combined treatment strategies of O 3 +H 2 O 2 and HC+O 3 +H 2 O 2 at the optimum conditions of temperature as 30°C, inlet pressure of 4bar and initial pH of 7. Extent of 2,4,6-TCP degradation, TOC and COD removal obtained for HC+O 3 process were 97.1%, 94.4% and 78.5% respectively whereas for O 3 +H 2 O 2 process, the values were 95.5%, 94.8% and 76.2% and for HC+O 3 +H 2 O 2 process the extent of reduction were 100%, 95.6% and 80.9% in the same order. The combined treatment approach as HC+O 3 +H 2 O 2 was established as the most efficient approach for complete removal of 2,4,6-TCP with near complete TOC removal. Copyright © 2017 Elsevier B.V. All rights reserved.

Cavitation for improved sludge conversion into biogas

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Stoop, A. H.; Bakker, T. W.; Kramer, H. J. M.

2015-12-01

In several studies the beneficial influence of pre-treatment of waste activated sludge with cavitation on the biogas production was demonstrated. It is however, still not fully certain whether this effect should be mainly contributed to an increase in conversion rate of organics into biogas by anaerobic bacteria, and how much cavitation increases the total biogas yield. An increase in yield is only the case if cavitation can further disrupt otherwise inaccessible cell membrane structures and long chain organic molecules. In this study the influence of hydrodynamic cavitation on sludge that was already digested for 30 days was investigated. The total biogas yield could indeed be increased. The effect of the backpressure behind the venturi tube on the yield could not yet be established.

The effects of waste-activated sludge pretreatment using hydrodynamic cavitation for methane production.

Science.gov (United States)

Lee, Ilgyu; Han, Jong-In

2013-11-01

Disintegration of waste-activated sludge (WAS) is regarded as a prerequisite of the anaerobic digestion (AD) process to reduce sludge volume and increase methane yield. Hydrodynamic cavitation (HC), which shares a similar underlying principle with ultrasonication but is energy-efficient, was employed as a physical means to break up WAS. Compared with ultrasonic (180-3600 kJ/kg TS) and thermal methods (72,000 kJ/kg TS), HC (60-1200 kJ/kg TS) found to consume significantly low power. A synergetic effect was observed when HC was combined with alkaline treatment in which NaOH, KOH, and Ca(OH)2 were used as alkaline catalysts at pH ranging from 8 to 13. As expected, the production yield of CH4 gas increased proportionally as WAS disintegration proceeded. HC, when combined with alkaline pretreatment, was found to be a cost-effective substitute to conventional methods for WAS pretreatment. Copyright © 2013 Elsevier B.V. All rights reserved.

Cavitation and thermal dilepton production in QGP

International Nuclear Information System (INIS)

Bhatt, Jitesh R.; Mishra, Hiranmaya; Sreekanth, V.

2012-01-01

We study the effects of bulk and shear viscosities on both hydrodynamical evolution and thermal dilepton emission rate from the QGP phase at RHIC energies. We use lattice QCD inspired parametrization for the bulk viscosity and trace anomaly (equation of state) to describe behavior of the system near the critical temperature T c . Ratio of the shear viscosity to entropy density is taken to be η/s∼1/4π. We calculate the corrections on the dilepton production rates due to modification in the distribution function, arising due to the presence of the bulk and shear viscosities. It is shown that when the system temperature evolves close to T c the effect of the bulk viscosity on the dilepton emission rates cannot be ignored. It is demonstrated that the bulk viscosity can suppress the thermal dilepton spectra where as the effect of the shear viscosity is to enhance it. Further we show that the bulk viscosity driven fragmentation or cavitation can set in very early during the hydrodynamical evolution and this in turn would make the hydrodynamical treatment invalid beyond the cavitation time. We find that even though the finite bulk viscosity corrections and the onset of the cavitation reduce the production rates, the effect of the minimal η/s=1/4π can enhance the dilepton production rates significantly in the regime p T ⩾2 GeV.

A Non-catalytic Deep Desulphurization Process using Hydrodynamic Cavitation

Science.gov (United States)

Suryawanshi, Nalinee B.; Bhandari, Vinay M.; Sorokhaibam, Laxmi Gayatri; Ranade, Vivek V.

2016-09-01

A novel approach is developed for desulphurization of fuels or organics without use of catalyst. In this process, organic and aqueous phases are mixed in a predefined manner under ambient conditions and passed through a cavitating device. Vapor cavities formed in the cavitating device are then collapsed which generate (in-situ) oxidizing species which react with the sulphur moiety resulting in the removal of sulphur from the organic phase. In this work, vortex diode was used as a cavitating device. Three organic solvents (n-octane, toluene and n-octanol) containing known amount of a model sulphur compound (thiophene) up to initial concentrations of 500 ppm were used to verify the proposed method. A very high removal of sulphur content to the extent of 100% was demonstrated. The nature of organic phase and the ratio of aqueous to organic phase were found to be the most important process parameters. The results were also verified and substantiated using commercial diesel as a solvent. The developed process has great potential for deep of various organics, in general, and for transportation fuels, in particular.

A critical pressure based panel method for prediction of unsteady loading of marine propellers under cavitation

International Nuclear Information System (INIS)

Liu, P.; Bose, N.; Colbourne, B.

2002-01-01

A simple numerical procedure is established and implemented into a time domain panel method to predict hydrodynamic performance of marine propellers with sheet cavitation. This paper describes the numerical formulations and procedures to construct this integration. Predicted hydrodynamic loads were compared with both a previous numerical model and experimental measurements for a propeller in steady flow. The current method gives a substantial improvement in thrust and torque coefficient prediction over a previous numerical method at low cavitation numbers of less than 2.0, where severe cavitation occurs. Predicted pressure coefficient distributions are also presented. (author)

Hydrodynamic Forces on Composite Structures

Science.gov (United States)

2014-06-01

NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited HYDRODYNAMIC ...Thesis 4. TITLE AND SUBTITLE HYDRODYNAMIC FORCES ON COMPOSITE STRUCTURES 5. FUNDING NUMBERS 6. AUTHOR(S) Scott C. Millhouse 7. PERFORMING...angles yields different free surface effects including vortices and the onset of cavitation . 14. SUBJECT TERMS Fluid structure interaction, FSI, finite

Intensification of esterification of non edible oil as sustainable feedstock using cavitational reactors.

Science.gov (United States)

Mohod, Ashish V; Subudhi, Abhijeet S; Gogate, Parag R

2017-05-01

Using sustainable feed stock such as non-edible oil for the biodiesel production can be one of the cost effective approaches considering the ever growing interest towards renewable energy and problems in existing approaches for production. However, due to the high free fatty acid content, non-edible oils require considerable preprocessing before the actual transesterification reaction for biodiesel production. The present work focuses on intensification of the esterification reaction used as preprocessing step based on acoustic and hydrodynamic cavitation also presenting the comparison with the conventional approach. Karanja oil with initial acid value as 14.15mg of KOH/g of oil has been used as a sustainable feedstock. Effect of operating parameters such as molar ratio, catalyst loading, temperature and type of catalyst (sulfuric acid and Amberlyst-15) on the acid value reduction has been investigated. The maximum reduction in the acid value (final acid value as 2.7mg of KOH/g of oil) was obtained using acoustic cavitation at optimum molar ratio of oil to methanol as 1:5 and 2% sulfuric acid loading at ambient temperature. In the case of hydrodynamic cavitation, acid value reduced upto 4.2mg of KOH under optimized conditions of first stage processing. In the second stage esterification using hydrodynamic cavitation and conventional approach, the final acid value was 3.6 and 3.8mg of KOH/g of oil respectively. Energy requirement analysis for ultrasound and conventional approaches clearly established the superiority of the ultrasound based approach. The present study clearly demonstrated that significant intensification benefits can be obtained in terms of the reduction in the molar ratio and operating temperature for the case of acoustic cavitation as compared to the conventional approach with somewhat lower effects for the hydrodynamic cavitation. Copyright © 2016 Elsevier B.V. All rights reserved.

Numerical investigation of cavitation flow in journal bearing geometry

Science.gov (United States)

Riedel, M.; Schmidt, M.; Stücke, P.

2013-04-01

The appearance of cavitation is still a problem in technical and industrial applications. Especially in automotive internal combustion engines, hydrodynamic journal bearings are used due to their favourable wearing quality and operating characteristics. Cavitation flows inside the bearings reduces the load capacity and leads to a risk of material damages. Therefore an understanding of the complex flow phenomena inside the bearing is necessary for the design development of hydrodynamic journal bearings. Experimental investigations in the fluid domain of the journal bearing are difficult to realize founded by the small dimensions of the bearing. In the recent years more and more the advantages of the computational fluid dynamics (CFD) are used to investigate the detail of the cavitation flows. The analysis in the paper is carried out in a two-step approach. At first an experimental investigation of journal bearing including cavitation is selected from the literature. The complex numerical model validated with the experimental measured data. In a second step, typically design parameters, such as a groove and feed hole, which are necessary to distribute the oil supply across the gap were added into the model. The paper reflects on the influence of the used design parameters and the variation of the additional supply flow rate through the feed hole regarding to cavitation effects in the bearing. Detailed pictures of the three-dimensional flow structures and the cavitation regions inside the flow film of the bearing are presented.

Numerical investigation of cavitation flow in journal bearing geometry

Directory of Open Access Journals (Sweden)

Stücke P.

2013-04-01

Full Text Available The appearance of cavitation is still a problem in technical and industrial applications. Especially in automotive internal combustion engines, hydrodynamic journal bearings are used due to their favourable wearing quality and operating characteristics. Cavitation flows inside the bearings reduces the load capacity and leads to a risk of material damages. Therefore an understanding of the complex flow phenomena inside the bearing is necessary for the design development of hydrodynamic journal bearings. Experimental investigations in the fluid domain of the journal bearing are difficult to realize founded by the small dimensions of the bearing. In the recent years more and more the advantages of the computational fluid dynamics (CFD are used to investigate the detail of the cavitation flows. The analysis in the paper is carried out in a two-step approach. At first an experimental investigation of journal bearing including cavitation is selected from the literature. The complex numerical model validated with the experimental measured data. In a second step, typically design parameters, such as a groove and feed hole, which are necessary to distribute the oil supply across the gap were added into the model. The paper reflects on the influence of the used design parameters and the variation of the additional supply flow rate through the feed hole regarding to cavitation effects in the bearing. Detailed pictures of the three-dimensional flow structures and the cavitation regions inside the flow film of the bearing are presented.

Degradation of a cationic dye (Rhodamine 6G) using hydrodynamic cavitation coupled with other oxidative agents: Reaction mechanism and pathway.

Science.gov (United States)

Rajoriya, Sunil; Bargole, Swapnil; Saharan, Virendra Kumar

2017-01-01

In the present study, decolorization and mineralization of a cationic dye, Rhodamine 6G (Rh6G), has been carried out using hydrodynamic cavitation (HC). Two cavitating devices such as slit and circular venturi were used to generate cavitation in HC reactor. The process parameters such as initial dye concentration, solution pH, operating inlet pressure, and cavitation number were investigated in detail to evaluate their effects on the decolorization efficiency of Rh6G. Decolorization of Rh6G was marginally higher in the case of slit venturi as compared to circular venturi. The kinetic study showed that decolorization and mineralization of the dye fitted first-order kinetics. The loadings of H 2 O 2 and ozone have been optimized to intensify the decolorization and mineralization efficiency of Rh6G using HC. Nearly 54% decolorization of Rh6G was obtained using a combination of HC and H 2 O 2 at a dye to H 2 O 2 molar ratio of 1:30. The combination of HC with ozone resulted in 100% decolorization in almost 5-10min of processing time depending upon the initial dye concentration. To quantify the extent of mineralization, total organic carbon (TOC) analysis was also performed using various processes and almost 84% TOC removal was obtained using HC coupled with 3g/h of ozone. The degradation by-products formed during the complete degradation process were qualitatively identified by liquid chromatography-mass spectrometry (LC-MS) and a detailed degradation pathway has been proposed. Copyright © 2016 Elsevier B.V. All rights reserved.

Modeling the shear rate and pressure drop in a hydrodynamic cavitation reactor with experimental validation based on KI decomposition studies.

Science.gov (United States)

Badve, Mandar P; Alpar, Tibor; Pandit, Aniruddha B; Gogate, Parag R; Csoka, Levente

2015-01-01

A mathematical model describing the shear rate and pressure variation in a complex flow field created in a hydrodynamic cavitation reactor (stator and rotor assembly) has been depicted in the present study. The design of the reactor is such that the rotor is provided with surface indentations and cavitational events are expected to occur on the surface of the rotor as well as within the indentations. The flow characteristics of the fluid have been investigated on the basis of high accuracy compact difference schemes and Navier-Stokes method. The evolution of streamlining structures during rotation, pressure field and shear rate of a Newtonian fluid flow have been numerically established. The simulation results suggest that the characteristics of shear rate and pressure area are quite different based on the magnitude of the rotation velocity of the rotor. It was observed that area of the high shear zone at the indentation leading edge shrinks with an increase in the rotational speed of the rotor, although the magnitude of the shear rate increases linearly. It is therefore concluded that higher rotational speeds of the rotor, tends to stabilize the flow, which in turn results into less cavitational activity compared to that observed around 2200-2500RPM. Experiments were carried out with initial concentration of KI as 2000ppm. Maximum of 50ppm of iodine liberation was observed at 2200RPM. Experimental as well as simulation results indicate that the maximum cavitational activity can be seen when rotation speed is around 2200-2500RPM. Copyright © 2014 Elsevier B.V. All rights reserved.

Study of a new static mixer for two-phase and single-phase flows

International Nuclear Information System (INIS)

Foucrier, Michel

1996-01-01

The subject of this work is the study of OptimiX, a new static mixer, which is fully designed using an inverse method taking the final product features as input and based on the physical properties of the fluid to mix. The work began with the construction of an experimental loop which allowed us to qualify the mixer in two-phase and single-phase flow conditions. Next, a chemical method using a new test reaction and a micro-mixing model have been used to further characterise the mixer. This test reaction and the micro-mixing model have been developed by the 'Laboratoire des Sciences du Genie Chimique' of Nancy. The mixer OptimiX has proved to be an excellent device for both macro- and micro-mixing. The capability of this mixer to foster rapid reactions was also demonstrated. The well organised flow pattern of OptimiX, which results from its design, provides it with the unusual feature of being fully calculable. This work emphasizes the internal hydrodynamics of this mixer, justifies the universality of the design procedures, which validation is supported by the completed qualification work. (author) [fr

Sonochemical and hydrodynamic cavitation reactors for laccase/hydrogen peroxide cotton bleaching.

Science.gov (United States)

Gonçalves, Idalina; Martins, Madalena; Loureiro, Ana; Gomes, Andreia; Cavaco-Paulo, Artur; Silva, Carla

2014-03-01

The main goal of this work is to develop a novel and environmental-friendly technology for cotton bleaching with reduced processing costs. This work exploits a combined laccase-hydrogen peroxide process assisted by ultrasound. For this purpose, specific reactors were studied, namely ultrasonic power generator type K8 (850 kHz) and ultrasonic bath equipment Ultrasonic cleaner USC600TH (45 kHz). The optimal operating conditions for bleaching were chosen considering the highest levels of hydroxyl radical production and the lowest energy input. The capacity to produce hydroxyl radicals by hydrodynamic cavitation was also assessed in two homogenizers, EmulsiFlex®-C3 and APV-2000. Laccase nanoemulsions were produced by high pressure homogenization using BSA (bovine serum albumin) as emulsifier. The bleaching efficiency of these formulations was tested and the results showed higher whiteness values when compared to free laccase. The combination of laccase-hydrogen peroxide process with ultrasound energy produced higher whiteness levels than those obtained by conventional methods. The amount of hydrogen peroxide was reduced 50% as well as the energy consumption in terms of temperature (reduction of 40 °C) and operating time (reduction of 90 min). Copyright © 2013 Elsevier Inc. All rights reserved.

Performance and emission characteristics of a stationary diesel engine fuelled by Schleichera Oleosa Oil Methyl Ester (SOME) produced through hydrodynamic cavitation process

OpenAIRE

Ashok Kumar Yadav; M. Emran Khan; Amit Pal; Uttam Ghosh

2018-01-01

In this study, the performance and emission characteristics of biodiesel blends of 10, 20, 30 and 50% from Schleichera Oleosa oil based on hydrodynamic cavitation were compared to diesel fuel, and found to be acceptable according to the EN 14214 and ASTM D 6751 standards. The tests have been performed using a single cylinder four stroke diesel engine at different loading condition with the blended fuel at the rated speed of 1500 rpm. SOME (Schleichera Oleosa Oil Methyl Ester) blended with die...

Complete Procedure for Fabrication of a Fused Silica Ultrarapid Microfluidic Mixer Used in Biophysical Measurements

Directory of Open Access Journals (Sweden)

Dena Izadi

2017-01-01

Full Text Available In this paper we present a method to fabricate a fused silica microfluidic device by employing low viscosity KMPR photoresists. The resulting device is a continuous-flow microfluidic mixer based on hydrodynamic focusing. The advantages of this new fabrication method compared to the traditional approach using a poly-silicon mask are simplification, and time and cost reduction, while still preserving the quality and the performance of the mixers. This process results in devices in which the focusing channel has an aspect ratio of 10:1. The newly-fabricated mixer is successfully used to observe the folding of the Pin1 WW domain at the microsecond time scale.

Numerical Modelling and Prediction of Erosion Induced by Hydrodynamic Cavitation

Science.gov (United States)

Peters, A.; Lantermann, U.; el Moctar, O.

2015-12-01

The present work aims to predict cavitation erosion using a numerical flow solver together with a new developed erosion model. The erosion model is based on the hypothesis that collapses of single cavitation bubbles near solid boundaries form high velocity microjets, which cause sonic impacts with high pressure amplitudes damaging the surface. The erosion model uses information from a numerical Euler-Euler flow simulation to predict erosion sensitive areas and assess the erosion aggressiveness of the flow. The obtained numerical results were compared to experimental results from tests of an axisymmetric nozzle.

Extending cavitation models to subcooled and superheated nozzle flow

International Nuclear Information System (INIS)

Schmidt, D.P.; Corradini, M.L.

1997-01-01

Existing models for cavitating flow are extended to apply to discharge of hot liquid through nozzles. Two types of models are considered: an analytical model and a two-dimensional numerical model. The analytical model of cavitating nozzle flow is reviewed and shown to apply to critical nozzle flow where the liquid is subcooled with respect to the downstream conditions. In this model the liquid and vapor are assumed to be in thermodynamic equilibrium. The success of this analytical model suggests that hydrodynamic effects dominate the subcooled nozzle flow. For more detailed predictions an existing multi-dimensional cavitation model based on hydrodynamic non-equilibrium is modified to apply to discharge of hot liquid. Non-equilibrium rate data from experimental measurements are used to close the equations. The governing equations are solved numerically in time and in two spatial dimensions on a boundary fitted grid. Results are shown for flow through sharp nozzles, and the coefficient of discharge is found to agree with experimental measurements for both subcooled and flashing fluid. (author)

Ultrafast cavitation induced by an X-ray laser in water drops

Science.gov (United States)

Stan, Claudiu; Willmott, Philip; Stone, Howard; Koglin, Jason; Liang, Mengning; Aquila, Andrew; Robinson, Joseph; Gumerlock, Karl; Blaj, Gabriel; Sierra, Raymond; Boutet, Sebastien; Guillet, Serge; Curtis, Robin; Vetter, Sharon; Loos, Henrik; Turner, James; Decker, Franz-Josef

2016-11-01

Cavitation in pure water is determined by an intrinsic heterogeneous cavitation mechanism, which prevents in general the experimental generation of large tensions (negative pressures) in bulk liquid water. We developed an ultrafast decompression technique, based on the reflection of shock waves generated by an X-ray laser inside liquid drops, to stretch liquids to large negative pressures in a few nanoseconds. Using this method, we observed cavitation in liquid water at pressures below -100 MPa. These large tensions exceed significantly those achieved previously, mainly due to the ultrafast decompression. The decompression induced by shock waves generated by an X-ray laser is rapid enough to continue to stretch the liquid phase after the heterogeneous cavitation occurs in water, despite the rapid growth of cavitation nanobubbles. We developed a nucleation-and-growth hydrodynamic cavitation model that explains our results and estimates the concentration of heterogeneous cavitation nuclei in water.

Transition of cavitating flow to supercavitation within Venturi nozzle - hysteresis investigation

Science.gov (United States)

Jiří, Kozák; Pavel, Rudolf; Rostislav, Huzlík; Martin, Hudec; Radomír, Chovanec; Ondřej, Urban; Blahoslav, Maršálek; Eliška, Maršálková; František, Pochylý; David, Štefan

Cavitation is usually considered as undesirable phenomena. On the other hand, it can be utilized in many applications. One of the technical applications is using cavitation in water treatment, where hydrodynamic cavitation seems to be effective way how to reduce cyanobacteria within large bulks of water. The main scope of this paper is investigation of the cavitation within Venturi nozzle during the transition from fully developed cavitation to supercavitation regime and vice versa. Dynamics of cavitation was investigated using experimental data of pressure pulsations and analysis of high speed videos, where FFT of the pixel intensity and Proper Orthogonal Decomposition (POD) of the records were done to identify dominant frequencies connected with the presence of cavitation. The methodology of the high speed (HS) records semiautomated analysis using the FFT was described. Obtained results were correlated and above that the possible presence of hysteresis was discussed.

International Symposium of Cavitation and Multiphase Flow (ISCM 2014)

International Nuclear Information System (INIS)

Wu, Yulin

2015-01-01

The International Symposium on Cavitation and Multiphase Flow (ISCM 2014) was held in Beijing, China during 18th-21st October, 2014, which was jointly organized by Tsinghua University, Beijing, China and Jiangsu University, Zhenjiang, China. The co-organizer was the State Key Laboratory of Hydroscience and Engineering, Beijing, China. Cavitation and multiphase flow is one of paramount topics of fluid mechanics with many engineering applications covering a broad range of topics, e.g. hydraulic machinery, biomedical engineering, chemical and process industry. In order to improve the performances of engineering facilities (e.g. hydraulic turbines) and to accelerate the development of techniques for medical treatment of serious diseases (e.g. tumors), it is essential to improve our understanding of cavitation and Multiphase Flow. For example, the present development towards the advanced hydrodynamic systems (e.g. space engine, propeller, hydraulic machinery system) often requires that the systems run under cavitating conditions and the risk of cavitation erosion needs to be controlled. The purpose of the ISCM 2014 was to discuss the state-of-the-art cavitation and multiphase flow research and their up-to-date applications, and to foster discussion and exchange of knowledge, and to provide an opportunity for the researchers, engineers and graduate students to report their latest outputs in these fields. Furthermore, the participants were also encouraged to present their work in progress with short lead time and discuss the encountered problems. ISCM 2014 covers all aspects of cavitation and Multiphase Flow, e.g. both fundamental and applied research with a focus on physical insights, numerical modelling and applications in engineering. Some specific topics are: Cavitating and Multiphase Flow in hydroturbines, pumps, propellers etc. Numerical simulation techniques Cavitation and multiphase flow erosion and anti-erosion techniques Measurement techniques for cavitation and

Numerical study of fluid motion in bioreactor with two mixers

Energy Technology Data Exchange (ETDEWEB)

Zheleva, I., E-mail: izheleva@uni-ruse.bg [Department of Heat Technology, Hydraulics and Ecology, Angel Kanchev University of Rousse, 8 Studentska str., 7017 Rousse (Bulgaria); Lecheva, A., E-mail: alecheva@uni-ruse.bg [Department of Mathematics, Angel Kanchev University of Rousse, 8 Studentska str., 7017 Rousse (Bulgaria)

2015-10-28

Numerical study of hydrodynamic laminar behavior of a viscous fluid in bioreactor with multiple mixers is provided in the present paper. The reactor is equipped with two disk impellers. The fluid motion is studied in stream function-vorticity formulation. The calculations are made by a computer program, written in MATLAB. The fluid structure is described and numerical results are graphically presented and commented.

Large eddy simulation of cavitating flows

Science.gov (United States)

Gnanaskandan, Aswin; Mahesh, Krishnan

2014-11-01

Large eddy simulation on unstructured grids is used to study hydrodynamic cavitation. The multiphase medium is represented using a homogeneous equilibrium model that assumes thermal equilibrium between the liquid and the vapor phase. Surface tension effects are ignored and the governing equations are the compressible Navier Stokes equations for the liquid/vapor mixture along with a transport equation for the vapor mass fraction. A characteristic-based filtering scheme is developed to handle shocks and material discontinuities in non-ideal gases and mixtures. A TVD filter is applied as a corrector step in a predictor-corrector approach with the predictor scheme being non-dissipative and symmetric. The method is validated for canonical one dimensional flows and leading edge cavitation over a hydrofoil, and applied to study sheet to cloud cavitation over a wedge. This work is supported by the Office of Naval Research.

Detection of cavitation in hydraulic turbines

Science.gov (United States)

Escaler, Xavier; Egusquiza, Eduard; Farhat, Mohamed; Avellan, François; Coussirat, Miguel

2006-05-01

An experimental investigation has been carried out in order to evaluate the detection of cavitation in actual hydraulic turbines. The methodology is based on the analysis of structural vibrations, acoustic emissions and hydrodynamic pressures measured in the machine. The proposed techniques have been checked in real prototypes suffering from different types of cavitation. In particular, one Kaplan, two Francis and one Pump-Turbine have been investigated in the field. Additionally, one Francis located in a laboratory has also been tested. First, a brief description of the general features of cavitation phenomenon is given as well as of the main types of cavitation occurring in hydraulic turbines. The work presented here is focused on the most important ones which are the leading edge cavitation due to its erosive power, the bubble cavitation because it affects the machine performance and the draft tube swirl that limits the operation stability. Cavitation detection is based on the previous understanding of the cavity dynamics and its location inside the machine. This knowledge has been gained from flow visualisations and measurements in laboratory devices such as a high-speed cavitation tunnel and a reduced scale turbine test rig. The main techniques are the study of the high frequency spectral content of the signals and of their amplitude demodulation for a given frequency band. Moreover, low frequency spectral content can also be used in certain cases. The results obtained for the various types of cavitation found in the selected machines are presented and discussed in detail in the paper. Conclusions are drawn about the best sensor, measuring location, signal processing and analysis for each type of cavitation, which serve to validate and to improve the detection techniques.

Theoretical model for cavitation erosion prediction in centrifugal pump impeller

International Nuclear Information System (INIS)

Rayan, M.A.; Mahgob, M.M.; Mostafa, N.H.

1990-01-01

Cavitation is known to have great effects on pump hydraulic and mechanical characteristics. These effects are mainly described by deviation in pump performance, increasing vibration and noise level as well as erosion of blade and casing materials. In the present work, only the hydrodynamic aspect of cavitation was considered. The efforts were directed toward the study of cavitation inception, cavity mechanics and material erosion in order to clarify the macrohydrodynamic aspects of cavitation erosive wear in real machines. As a result of this study, it was found that cavitation damage can be predicted from model data. The obtained theoretical results show good agreement with the experimental results obtained in this investigation and with results of some other investigations. The application of the findings of this work will help the design engineer in predicting the erosion rate, according to the different operating conditions. (author)

Cavitation Erosion in Hydraulic Turbine Components and Mitigation by Coatings: Current Status and Future Needs

Science.gov (United States)

Singh, Raghuvir; Tiwari, S. K.; Mishra, Suman K.

2012-07-01

Cavitation erosion is a frequently observed phenomenon in underwater engineering materials and is the primary reason for component failure. The damage due to cavitation erosion is not yet fully understood, as it is influenced by several parameters, such as hydrodynamics, component design, environment, and material chemistry. This article gives an overview of the current state of understanding of cavitation erosion of materials used in hydroturbines, coatings and coating methodologies for combating cavitation erosion, and methods to characterize cavitation erosion. No single material property fully characterizes the resistance to cavitation erosion. The combination of ultimate resilience, hardness, and toughness rather may be useful to estimate the cavitation erosion resistance of material. Improved hydrodynamic design and appropriate surface engineering practices reduce damage due to cavitation erosion. The coatings suggested for combating the cavitation erosion encompasses carbides (WC Cr2C3, Cr3C2, 20CrC-80WC), cermets of different compositions (e.g., 56W2C/Ni/Cr, 41WC/Ni/Cr/Co), intermetallic composites, intermetallic matrix composites with TiC reinforcement, composite nitrides such as TiAlN and elastomers. A few of them have also been used commercially. Thermal spraying, arc plasma spraying, and high velocity oxy-fuel (HVOF) processes have been used commercially to apply the coatings. Boronizing, laser surface hardening and cladding, chemical vapor deposition, physical vapor deposition, and plasma nitriding have been tried for surface treatments at laboratory levels and have shown promise to be used on actual components.

Transition of cavitating flow to supercavitation within Venturi nozzle – hysteresis investigation

Directory of Open Access Journals (Sweden)

Jiří Kozák

2017-01-01

Full Text Available Cavitation is usually considered as undesirable phenomena. On the other hand, it can be utilized in many applications. One of the technical applications is using cavitation in water treatment, where hydrodynamic cavitation seems to be effective way how to reduce cyanobacteria within large bulks of water. The main scope of this paper is investigation of the cavitation within Venturi nozzle during the transition from fully developed cavitation to supercavitation regime and vice versa. Dynamics of cavitation was investigated using experimental data of pressure pulsations and analysis of high speed videos, where FFT of the pixel intensity and Proper Orthogonal Decomposition (POD of the records were done to identify dominant frequencies connected with the presence of cavitation. The methodology of the high speed (HS records semiautomated analysis using the FFT was described. Obtained results were correlated and above that the possible presence of hysteresis was discussed.

Disinfection of bore well water with chlorine dioxide/sodium hypochlorite and hydrodynamic cavitation.

Science.gov (United States)

Wang, Yifei; Jia, Aiyin; Wu, Yue; Wu, Chunde; Chen, Lijun

2015-01-01

The effect of hydrodynamic cavitation (HC) on potable water disinfection of chemicals was investigated. The bore well water was introduced into HC set-up to examine the effect of HC alone and combination of HC and chemicals such as chlorine dioxide and sodium hypochlorite. The effect of inlet pressure and geometrical parameters on disinfection was studied using HC alone and the results showed that increasing inlet pressure and using more and bigger holes of orifice plates can result in a higher disinfection rates. When HC was combined with chemicals, HC can reduce the doses of the chemicals and shorten the time of disinfection. It was also found that the decrease in bacteria concentration followed a first-order kinetic model. As for the experiment of combination of HC and sodium hypochlorite for disinfection, HC not only improves the disinfection rate but also degrades natural organic matter and chloroform. Compared with only sodium hypochlorite disinfection, combined processes get higher disinfection rate and lower production of chloroform, particularly the pretreatment with HC enhances the disinfection rate by 32% and there is a simultaneous reduction in production of chloroform by 39%.

Hydrodynamics of Ship Propellers

DEFF Research Database (Denmark)

Breslin, John P.; Andersen, Poul

This book deals with flows over propellers operating behind ships, and the hydrodynamic forces and moments which the propeller generates on the shaft and on the ship hull.The first part of the text is devoted to fundamentals of the flow about hydrofoil sections (with and without cavitation...... of an intermittently cavitating propeller in a wake and the pressures and forces it exerts on the shaft and on the ship hull is examined. A final chapter discusses the optimization of efficiency of compound propulsors. The authors have taken care to clearly describe physical concepts and mathematical steps. Appendices...

Pilot scale intensification of rubber seed (Hevea brasiliensis) oil via chemical interesterification using hydrodynamic cavitation technology.

Science.gov (United States)

Bokhari, Awais; Yusup, Suzana; Chuah, Lai Fatt; Klemeš, Jiří Jaromír; Asif, Saira; Ali, Basit; Akbar, Majid Majeed; Kamil, Ruzaimah Nik M

2017-10-01

Chemical interesterification of rubber seed oil has been investigated for four different designed orifice devices in a pilot scale hydrodynamic cavitation (HC) system. Upstream pressure within 1-3.5bar induced cavities to intensify the process. An optimal orifice plate geometry was considered as plate with 1mm dia hole having 21 holes at 3bar inlet pressure. The optimisation results of interesterification were revealed by response surface methodology; methyl acetate to oil molar ratio of 14:1, catalyst amount of 0.75wt.% and reaction time of 20min at 50°C. HC is compared to mechanical stirring (MS) at optimised values. The reaction rate constant and the frequency factor of HC were 3.4-fold shorter and 3.2-fold higher than MS. The interesterified product was characterised by following EN 14214 and ASTM D 6751 international standards. Copyright © 2017 Elsevier Ltd. All rights reserved.

Numerical simulation of wall roughness effects in cavitating flow

International Nuclear Information System (INIS)

Echouchene, F.; Belmabrouk, H.; Le Penven, L.; Buffat, M.

2011-01-01

Hydrodynamic cavitation has an important effect on the performance of Diesel injectors. It influences the nature of the fuel spray and the efficiency of the combustion process. In the present study, we investigate numerically the effect of wall roughness in the cavitating and turbulent flow developing inside a Diesel injector. The mixture model based on a single fluid is adopted and the commercial Fluent software is used to solve the transport equations. The discharge coefficient C d is computed for different cavitation numbers and wall roughness heights. Profiles of density mixture, vapor volume fraction, mean velocity and turbulent kinetic energy are reported. The effects of wall roughness and injection pressure are analyzed.

Numerical simulation of wall roughness effects in cavitating flow

Energy Technology Data Exchange (ETDEWEB)

Echouchene, F. [Laboratoire d' electronique et de microelectronique, Departement de Physique, Faculte des Sciences de Monastir, 5000 (Tunisia); Belmabrouk, H., E-mail: frchouchene@yahoo.fr [Laboratoire d' electronique et de microelectronique, Departement de Physique, Faculte des Sciences de Monastir, 5000 (Tunisia); Le Penven, L.; Buffat, M. [LMFA UMR CNRS 5509, Universite de Claude Bernard Lyon 1, Ecole Centrale de Lyon, INSA de Lyon (France)

2011-10-15

Hydrodynamic cavitation has an important effect on the performance of Diesel injectors. It influences the nature of the fuel spray and the efficiency of the combustion process. In the present study, we investigate numerically the effect of wall roughness in the cavitating and turbulent flow developing inside a Diesel injector. The mixture model based on a single fluid is adopted and the commercial Fluent software is used to solve the transport equations. The discharge coefficient C{sub d} is computed for different cavitation numbers and wall roughness heights. Profiles of density mixture, vapor volume fraction, mean velocity and turbulent kinetic energy are reported. The effects of wall roughness and injection pressure are analyzed.

FOREWORD: International Symposium of Cavitation and Multiphase Flow (ISCM 2014)

Science.gov (United States)

Wu, Yulin

2015-01-01

The International Symposium on Cavitation and Multiphase Flow (ISCM 2014) was held in Beijing, China during 18th-21st October, 2014, which was jointly organized by Tsinghua University, Beijing, China and Jiangsu University, Zhenjiang, China. The co-organizer was the State Key Laboratory of Hydroscience and Engineering, Beijing, China. Cavitation and multiphase flow is one of paramount topics of fluid mechanics with many engineering applications covering a broad range of topics, e.g. hydraulic machinery, biomedical engineering, chemical and process industry. In order to improve the performances of engineering facilities (e.g. hydraulic turbines) and to accelerate the development of techniques for medical treatment of serious diseases (e.g. tumors), it is essential to improve our understanding of cavitation and Multiphase Flow. For example, the present development towards the advanced hydrodynamic systems (e.g. space engine, propeller, hydraulic machinery system) often requires that the systems run under cavitating conditions and the risk of cavitation erosion needs to be controlled. The purpose of the ISCM 2014 was to discuss the state-of-the-art cavitation and multiphase flow research and their up-to-date applications, and to foster discussion and exchange of knowledge, and to provide an opportunity for the researchers, engineers and graduate students to report their latest outputs in these fields. Furthermore, the participants were also encouraged to present their work in progress with short lead time and discuss the encountered problems. ISCM 2014 covers all aspects of cavitation and Multiphase Flow, e.g. both fundamental and applied research with a focus on physical insights, numerical modelling and applications in engineering. Some specific topics are: Cavitating and Multiphase Flow in hydroturbines, pumps, propellers etc. Numerical simulation techniques Cavitation and multiphase flow erosion and anti-erosion techniques Measurement techniques for cavitation and

Investigation of cavitating flows by X-ray and optical imaging

Science.gov (United States)

Coutier-Delgosha, Olivier; Fuzier, Sylvie; Khlifa, Ilyass; Fezzaa, Kamel

2015-11-01

Hydrodynamic cavitation is the partial vaporization of high speed liquid flows. The turbulent, compressible and unsteady character of these flows makes their study unusually complex and challenging. Instabilities generated by the occurrence of cavitation have been investigated in the last years in the LML laboratory by various non-intrusive measurements including X-ray imaging (to obtain the fields of void fraction and velocity in both phases), and PIV with fluorescent particles (to obtain the velocity fields in both phases). It has been shown that cavitation is characterized by significant slip velocities between liquid and vapor, especially in the re-entrant jet area and the cavity wake. This results suggests some possible improvements in the numerical models currently used for CFD of cavitating flows. Professor at Arts et Metiers ParisTech, Director of the LML laboratory.

Correlating Inertial Acoustic Cavitation Emissions with Material Erosion Resistance

Science.gov (United States)

Ibanez, I.; Hodnett, M.; Zeqiri, B.; Frota, M. N.

The standard ASTM G32-10 concerns the hydrodynamic cavitation erosion resistance of materials by subjecting them to acoustic cavitation generated by a sonotrode. The work reported extends this technique by detecting and monitoring the ultrasonic cavitation, considered responsible for the erosion process, specifically for coupons of aluminium-bronze alloy. The study uses a 65 mm diameter variant of NPL's cavitation sensor, which detects broadband acoustic emissions, and logs acoustic signals generated in the MHz frequency range, using NPL's Cavimeter. Cavitation readings were made throughout the exposure duration, which was carried out at discrete intervals (900 to 3600 s), allowing periodic mass measurements to be made to assess erosion loss under a strict protocol. Cavitation measurements and erosion were compared for different separations of the sonotrode tip from the material under test. The maximum variation associated with measurement of cavitation level was between 2.2% and 3.3% when the separation (λ) between the transducer horn and the specimen increased from 0.5 to 1.0 mm, for a transducer (sonotrode) displacement amplitude of 43.5 μm. Experiments conducted at the same transducer displacement amplitude show that the mass loss of the specimen -a measure of erosion- was 67.0 mg (λ = 0.5 mm) and 66.0 mg (λ = 1.0 mm).

Terahertz radiation mixer

Science.gov (United States)

Wanke, Michael C [Albuquerque, NM; Allen, S James [Santa Barbara, CA; Lee, Mark [Albuquerque, NM

2008-05-20

A terahertz radiation mixer comprises a heterodyned field-effect transistor (FET) having a high electron mobility heterostructure that provides a gatable two-dimensional electron gas in the channel region of the FET. The mixer can operate in either a broadband pinch-off mode or a narrowband resonant plasmon mode by changing a grating gate bias of the FET. The mixer can beat an RF signal frequency against a local oscillator frequency to generate an intermediate frequency difference signal in the microwave region. The mixer can have a low local oscillator power requirement and a large intermediate frequency bandwidth. The terahertz radiation mixer is particularly useful for terahertz applications requiring high resolution.

Intensified depolymerization of aqueous polyacrylamide solution using combined processes based on hydrodynamic cavitation, ozone, ultraviolet light and hydrogen peroxide.

Science.gov (United States)

Prajapat, Amrutlal L; Gogate, Parag R

2016-07-01

The present work deals with intensification of depolymerization of polyacrylamide (PAM) solution using hydrodynamic cavitation (HC) reactors based on a combination with hydrogen peroxide (H2O2), ozone (O3) and ultraviolet (UV) irradiation. Effect of inlet pressure in hydrodynamic cavitation reactor and power dissipation in the case of UV irradiation on the extent of viscosity reduction has been investigated. The combined approaches such as HC+UV, HC+O3, HC+H2O2, UV+H2O2 and UV+O3 have been subsequently investigated and found to be more efficient as compared to individual approaches. For the approach based on HC+UV+H2O2, the extent of viscosity reduction under the optimized conditions of HC (3 bar inlet pressure)+UV (8 W power)+H2O2 (0.2% loading) was 97.27% in 180 min whereas individual operations of HC (3 bar inlet pressure) and UV (8 W power) resulted in about 35.38% and 40.83% intrinsic viscosity reduction in 180 min respectively. In the case of HC (3 bar inlet pressure)+UV (8 W power)+ozone (400 mg/h flow rate) approach, the extent of viscosity reduction was 89.06% whereas individual processes of only ozone (400 mg/h flow rate), ozone (400 mg/h flow rate)+HC (3 bar inlet pressure) and ozone (400 mg/h flow rate)+UV (8 W power) resulted in lower extent of viscosity reduction as 50.34%, 60.65% and 75.31% respectively. The chemical structure of the treated PAM by all approaches was also characterized using FTIR (Fourier transform infrared) spectra and it was established that no significant chemical structure changes were obtained during the treatment. Overall, it can be said that the combination of HC+UV+H2O2 is an efficient approach for the depolymerization of PAM solution. Copyright © 2016 Elsevier B.V. All rights reserved.

Cavitation in flow through a micro-orifice inside a silicon microchannel

Science.gov (United States)

Mishra, Chandan; Peles, Yoav

2005-01-01

Hydrodynamic cavitation in flows through a micro-orifice entrenched in a microchannel has been detected and experimentally investigated. Microfabrication techniques have been employed to design and develop a microfluidic device containing an 11.5μm wide micro-orifice inside a 100.2μm wide and 101.3μm deep microchannel. The flow of de-ionized water through the micro-orifice reveals the presence of multifarious cavitating flow regimes. This investigation divulges both similarities and differences between cavitation in micro-orifices and cavitation in their macroscale counterparts. The low incipient cavitation number obtained from the current experiments suggests a dominant size scale effect. Choking cavitation is observed to be independent of any pressure or velocity scale effects. However, choking is significantly influenced by the small stream nuclei residence time at such scales. Flow rate choking leads to the establishment of a stationary cavity. Large flow and cavitation hysteresis have been detected at the microscale leading to very high desinent cavitation numbers. The rapid transition from incipient bubbles to choking cavitation and subsequent supercavitation suggests the presence of radically different flow patterns at the microscale. Supercavitation results in a thick cavity, which extends throughout the microchannel, and is encompassed by the liquid. Cavitation at the microscale is expected to considerably influence the design of innovative high-speed microfluidic systems.

Study on Effects of The Shape of Cavitator on Supercavitation Flow Field Characteristics

Science.gov (United States)

Wang, Rui; Dang, Jianjun; Yao, Zhong

2018-03-01

The cavitator is the key part of the nose of the vehicle to induce the formation of supercavity, which has an important influence in the cavity formation rate, cavity shape and cavity stability. To study the influence of the shape on the supercavitation flew field characteristics, the cavity characteristics and the resistance characteristics of different shapes of cavitator under different working conditions are obtained by combining technical methods of numerical simulation and experimental research in water tunnel. The simulation results are contrast and analyzed with the test results. The analysis results show that : in terms of the cavity size, the inverted-conic cavitator can form the biggest cavity size, followed by the disk cavitator, and the truncated-conic cavitator is the least; in terms of the cavity formation speed, the inverted-conic cavitator has the fastest cavity formation speed, then is the truncated-conic cavitator, and the disk cavitator is the least; in terms of the drag characteristic, the truncated-conic cavitator has the maximum coefficient, disk cavitator is the next, the inverted-conic cavitator is the minimal. The research conclusion can provide reference and basis for the head shape design of supercavitating underwater ordnance and the design of hydrodynamic layout.

Hydrodynamical tests with an original PWR heat removal pump

International Nuclear Information System (INIS)

Wietstock, P.

1984-01-01

GKSS-Forschungszentrum performes hydrodynamical tests with an original PWR heat removal pump to analyse the influences of fluid parameters on the capacity and cavitation behavior of the pump in order to get further improvements of the quantification of the reached safety-level. It can be concluded, that in case of the tested heat removal pump the additional loads during transition from cavitation free operation into fully cavitation for the investigated operation point with 980 m 3 /h will be smaller than the alteration of loads during passing through the total characteristic. The results from cavitation tests for other operation points indicate, that this very important consequence especially for accident operation will be valid for the total specified pump flow area. (orig.)

Numerical analysis of the effects of radiation heat transfer and ionization energy loss on the cavitation Bubble's dynamics

International Nuclear Information System (INIS)

Mahdi, M.; Ebrahimi, R.; Shams, M.

2011-01-01

A numerical scheme for simulating the acoustic and hydrodynamic cavitation was developed. Bubble instantaneous radius was obtained using Gilmore equation which considered the compressibility of the liquid. A uniform temperature was assumed for the inside gas during the collapse. Radiation heat transfer inside the bubble and the heat conduction to the bubble was considered. The numerical code was validated with the experimental data and a good correspondence was observed. The dynamics of hydrofoil cavitation bubble were also investigated. It was concluded that the thermal radiation heat transfer rate strongly depended on the cavitation number, initial bubble radius and hydrofoil angle of attack. -- Highlights: → Heat transfer and ionization energy losses were analyzed in the cavitation bubble. → Radiation of hydrodynamic bubble was approximately equal to the black body. → Radiation heat transfer did not affect the bubble dynamic. → Conduction decreased the bubble pressure and increased the bubble temperature. → Ionization decreased the temperature and increased the pressure in the bubble.

Optimisation on pretreatment of rubber seed (Hevea brasiliensis) oil via esterification reaction in a hydrodynamic cavitation reactor.

Science.gov (United States)

Bokhari, Awais; Chuah, Lai Fatt; Yusup, Suzana; Klemeš, Jiří Jaromír; Kamil, Ruzaimah Nik M

2016-01-01

Pretreatment of the high free fatty acid rubber seed oil (RSO) via esterification reaction has been investigated by using a pilot scale hydrodynamic cavitation (HC) reactor. Four newly designed orifice plate geometries are studied. Cavities are induced by assisted double diaphragm pump in the range of 1-3.5 bar inlet pressure. An optimised plate with 21 holes of 1mm diameter and inlet pressure of 3 bar resulted in RSO acid value reduction from 72.36 to 2.64 mg KOH/g within 30 min of reaction time. Reaction parameters have been optimised by using response surface methodology and found as methanol to oil ratio of 6:1, catalyst concentration of 8 wt%, reaction time of 30 min and reaction temperature of 55°C. The reaction time and esterified efficiency of HC was three fold shorter and four fold higher than mechanical stirring. This makes the HC process more environmental friendly. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of cavitation on the passive behaviour of duplex stainless steels in aqueous LiBr solutions

International Nuclear Information System (INIS)

Garcia-Garcia, D.M.; Garcia-Anton, J.; Igual-Munoz, A.

2008-01-01

The objective of this work is to study the influence of cavitation on the passive behaviour of EN 1.4462, its filler metal (EN 1.4462F), and the welded metal (EN 1.4462W) obtained by Gas Tungsten Arc Welding using electrochemical techniques. The hydrodynamic conditions of the medium were modified using an ultrasonic-induced cavitation facility. Potentiostatic experiments were used to study the effects of cavitation on the passive behaviour of the alloys. The experiments were carried out in 850 g/L LiBr solutions with and without an inhibitor (Lithium Chromate). The solution with Li 2 CrO 4 (commercial solution) contains LiOH as the pH regulator. The potentiodynamic cyclic curves of the stainless steels under the static condition were used to set the values of the imposed potentials. In this work, the electrochemical behaviour of the alloys described by the potentiodynamic curves has been related to their passive behaviour under potentiostatic conditions when the pulses of cavitation were applied. The results demonstrate that cavitation affects the passive behaviour of the alloys; the influence depends on the potential applied and on the presence or absence of chromates in the medium. Only under certain circumstances the hydrodynamic conditions can suppose a breakdown of passive film formed under static conditions

Lubrication and thermal characteristics of mechanical seal with porous surface based on cavitation

Science.gov (United States)

Huilong, Chen; Muzi, Zuo; Tong, Liu; Yu, Wang; Cheng, Xu; Qiangbo, Wu

2014-04-01

The theory model of mechanical seals with laser-textured porous surface (LST-MS) was established. The liquid film of LST-MS was simulated by the Fluent software, using full cavitation model and non-cavitation model separately. Dynamic mesh technique and relationship between viscosity and temperature were applied to simulate the internal flow field and heat characteristics of LST-MS, based on the more accurate cavitation model. Influence of porous depth ratio porous diameter ɛ and porous density SP on lubrication performance and the variation of lubrication and thermal properties with shaft speed and sealing pressure were analyzed. The results indicate that the strongest hydrodynamic pressure effect and the biggest thickness of liquid film are obtained when ɛ and SP are respectively about 0.025 and 0.5 which were thought to be the optimum value. The frictional heat leads to the increase of liquid film temperature and the decrease of medium viscosity with the shaft speed increasing. The hydrodynamic pressure effect increases as shaft speed increasing, however it decreases as the impact of frictional heat.

Cavitation

International Nuclear Information System (INIS)

Anon.

1983-01-01

Cavitation in fluid machines or flow passages can cause loss of performance or material damage due to erosion. This conference reports the results of world-wide research into all aspects of the study of cavitation. Contents include: Cavitation effects in machinery such as pumps, water turbines, propellers and positive displacement machinery; Cavitation in structures, flow passages, valves, flow meters and bearings; Cavitation erosion, noise and instability effects; Cavitation inception; Developed flows; Supercavitating flows and machines; Fundamentals; Bubble dynamics and thermodynamics of cavitation in various fluids; Test facilities and methods of cavitation research and testing; Special instrumentation for cavitation studies, and standards and recommendations for cavitation or erosion

Degradation of ibuprofen by hydrodynamic cavitation: Reaction pathways and effect of operational parameters.

Science.gov (United States)

Musmarra, Dino; Prisciandaro, Marina; Capocelli, Mauro; Karatza, Despina; Iovino, Pasquale; Canzano, Silvana; Lancia, Amedeo

2016-03-01

Ibuprofen (IBP) is an anti-inflammatory drug whose residues can be found worldwide in natural water bodies resulting in harmful effects to aquatic species even at low concentrations. This paper deals with the degradation of IBP in water by hydrodynamic cavitation in a convergent-divergent nozzle. Over 60% of ibuprofen was degraded in 60 min with an electrical energy per order (EEO) of 10.77 kWh m(-3) at an initial concentration of 200 μg L(-1) and a relative inlet pressure pin=0.35 MPa. Five intermediates generated from different hydroxylation reactions were identified; the potential mechanisms of degradation were sketched and discussed. The reaction pathways recognized are in line with the relevant literature, both experimental and theoretical. By varying the pressure upstream the constriction, different degradation rates were observed. This effect was discussed according to a numerical simulation of the hydroxyl radical production identifying a clear correspondence between the maximum kinetic constant kOH and the maximum calculated OH production. Furthermore, in the investigated experimental conditions, the pH parameter was found not to affect the extent of degradation; this peculiar feature agrees with a recently published kinetic insight and has been explained in the light of the intermediates of the different reaction pathways. Copyright © 2015 Elsevier B.V. All rights reserved.

Submillisecond mixing in a continuous-flow, microfluidic mixer utilizing mid-infrared hyperspectral imaging detection.

Science.gov (United States)

Kise, Drew P; Magana, Donny; Reddish, Michael J; Dyer, R Brian

2014-02-07

We report a continuous-flow, microfluidic mixer utilizing mid-infrared hyperspectral imaging detection, with an experimentally determined, submillisecond mixing time. The simple and robust mixer design has the microfluidic channels cut through a polymer spacer that is sandwiched between two IR transparent windows. The mixer hydrodynamically focuses the sample stream with two side flow channels, squeezing it into a thin jet and initiating mixing through diffusion and advection. The detection system generates a mid-infrared hyperspectral absorbance image of the microfluidic sample stream. Calibration of the hyperspectral image yields the mid-IR absorbance spectrum of the sample versus time. A mixing time of 269 μs was measured for a pD jump from 3.2 to above 4.5 in a D2O sample solution of adenosine monophosphate (AMP), which acts as an infrared pD indicator. The mixer was further characterized by comparing experimental results with a simulation of the mixing of an H2O sample stream with a D2O sheath flow, showing good agreement between the two. The IR microfluidic mixer eliminates the need for fluorescence labeling of proteins with bulky, interfering dyes, because it uses the intrinsic IR absorbance of the molecules of interest, and the structural specificity of IR spectroscopy to follow specific chemical changes such as the protonation state of AMP.

Decolorization of azo dyes Orange G using hydrodynamic cavitation coupled with heterogeneous Fenton process.

Science.gov (United States)

Cai, Meiqiang; Su, Jie; Zhu, Yizu; Wei, Xiaoqing; Jin, Micong; Zhang, Haojie; Dong, Chunying; Wei, Zongsu

2016-01-01

The present work demonstrates the application of the combination of hydrodynamic cavitation (HC) and the heterogeneous Fenton process (HF, Fe(0)/H2O2) for the decolorization of azo dye Orange G (OG). The effects of main affecting operation conditions such as the inlet fluid pressure, initial concentration of OG, H2O2 and zero valent iron (ZVI), the fixed position of ZVI, and medium pH on decolorization efficiency were discussed with guidelines for selection of optimum parameters. The results revealed that the acidic conditions are preferred for OG decolorizaiton. The decolorization rate increased with increasing H2O2 and ZVI concentration and decreased with increasing OG initial concentration. Besides, the decolorization rate was strongly dependent on the fixed position of ZVI. The analysis results of degradation products using liquid chromatography-ESI-TOF mass spectrometry revealed that the degradation mechanism of OG proceeds mainly via reductive cleavage of the azo linkage due to the attack of hydroxyl radical. The present work has conclusively established that the combination of HC and HF can be more energy efficient and gives higher decolorization rate of OG as compared with HC and HF alone. Copyright © 2015 Elsevier B.V. All rights reserved.

Inducer Hydrodynamic Load Measurement Devices

Science.gov (United States)

Skelley, Stephen E.; Zoladz, Thomas F.

2002-01-01

Marshall Space Flight Center (MSFC) has demonstrated two measurement devices for sensing and resolving the hydrodynamic loads on fluid machinery. The first - a derivative of the six component wind tunnel balance - senses the forces and moments on the rotating device through a weakened shaft section instrumented with a series of strain gauges. This "rotating balance" was designed to directly measure the steady and unsteady hydrodynamic loads on an inducer, thereby defining both the amplitude and frequency content associated with operating in various cavitation modes. The second device - a high frequency response pressure transducer surface mounted on a rotating component - was merely an extension of existing technology for application in water. MSFC has recently completed experimental evaluations of both the rotating balance and surface-mount transducers in a water test loop. The measurement bandwidth of the rotating balance was severely limited by the relative flexibility of the device itself, resulting in an unexpectedly low structural bending mode and invalidating the higher frequency response data. Despite these limitations, measurements confirmed that the integrated loads on the four-bladed inducer respond to both cavitation intensity and cavitation phenomena. Likewise, the surface-mount pressure transducers were subjected to a range of temperatures and flow conditions in a non-rotating environment to record bias shifts and transfer functions between the transducers and a reference device. The pressure transducer static performance was within manufacturer's specifications and dynamic response accurately followed that of the reference.

An Optical Characterization of the Effect of High-Pressure Hydrodynamic Cavitation on Diesel

OpenAIRE

Lockett, R. D.; Fatmi, Z.; Kuti, O.; Price, R.

2016-01-01

Most modern high-pressure common rail diesel fuel injection systems employ an internal pressure equalization system in order to provide the force necessary to support needle lift, enabling precise control of the injected fuel mass. This results in the return of a substantial proportion of the high-pressure diesel back to the fuel tank. The diesel fuel flow occurring in the injector spill passages is expected to be a cavitating flow, which is known to promote fuel ageing. The cavitation of die...

Numerical analysis of the effects of radiation heat transfer and ionization energy loss on the cavitation Bubble's dynamics

Energy Technology Data Exchange (ETDEWEB)

Mahdi, M. [Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Ebrahimi, R. [Faculty of Aerospace Engineering, K.N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Shams, M., E-mail: shams@kntu.ac.ir [Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Pardis St., Molla-Sadra Ave, Vanak. Sq., P.O. Box: 19395-1999, Tehran (Iran, Islamic Republic of)

2011-06-13

A numerical scheme for simulating the acoustic and hydrodynamic cavitation was developed. Bubble instantaneous radius was obtained using Gilmore equation which considered the compressibility of the liquid. A uniform temperature was assumed for the inside gas during the collapse. Radiation heat transfer inside the bubble and the heat conduction to the bubble was considered. The numerical code was validated with the experimental data and a good correspondence was observed. The dynamics of hydrofoil cavitation bubble were also investigated. It was concluded that the thermal radiation heat transfer rate strongly depended on the cavitation number, initial bubble radius and hydrofoil angle of attack. -- Highlights: → Heat transfer and ionization energy losses were analyzed in the cavitation bubble. → Radiation of hydrodynamic bubble was approximately equal to the black body. → Radiation heat transfer did not affect the bubble dynamic. → Conduction decreased the bubble pressure and increased the bubble temperature. → Ionization decreased the temperature and increased the pressure in the bubble.

Dynamics and noise emission of laser induced cavitation bubbles in a vortical flow field

Science.gov (United States)

Oweis, Ghanem F.; Choi, Jaehyug; Ceccio, Steven L.

2004-03-01

The sound produced by the collapse of discrete cavitation bubbles was examined. Laser-generated cavitation bubbles were produced in both a quiescent and a vortical flow. The sound produced by the collapse of the cavitation bubbles was recorded, and its spectral content was determined. It was found that the risetime of the sound pulse produced by the collapse of single, spherical cavitation bubbles in quiescent fluid exceeded that of the slew rate of the hydrophone, which is consistent with previously published results. It was found that, as collapsing bubbles were deformed by the vortical flow, the acoustic impulse of the bubbles was reduced. Collapsing nonspherical bubbles often created a sound pulse with a risetime that exceeded that of the hydrophone slew rate, although the acoustic impulse created by the bubbles was influenced largely by the degree to which the bubbles became nonspherical before collapse. The noise produced by the slow growth of cavitation bubbles in the vortex core was not detectable. These results have implications for the interpretation of hydrodynamic cavitation noise produced by vortex cavitation.

Optimization of a heterogeneous catalytic hydrodynamic cavitation reactor performance in decolorization of Rhodamine B: application of scrap iron sheets.

Science.gov (United States)

Basiri Parsa, Jalal; Ebrahimzadeh Zonouzian, Seyyed Alireza

2013-11-01

A low pressure pilot scale hydrodynamic cavitation (HC) reactor with 30 L volume, using fixed scrap iron sheets, as the heterogeneous catalyst, with no external source of H2O2 was devised to investigate the effects of operating parameters of the HC reactor performance. In situ generation of Fenton reagents suggested an induced advanced Fenton process (IAFP) to explain the enhancing effect of the used catalyst in the HC process. The reactor optimization was done based upon the extent of decolorization (ED) of aqueous solution of Rhodamine B (RhB). To have a perfect study on the pertinent parameters of the heterogeneous catalyzed HC reactor, the following cases as, the effects of scrap iron sheets, inlet pressure (2.4-5.8 bar), the distance between orifice plates and catalyst sheets (submerged and inline located orifice plates), back-pressure (2-6 bar), orifice plates type (4 various orifice plates), pH (2-10) and initial RhB concentration (2-14 mg L(-1)) have been investigated. The results showed that the highest cavitational yield can be obtained at pH 3 and initial dye concentration of 10 mg L(-1). Also, an increase in the inlet pressure would lead to an increase in the ED. In addition, it was found that using the deeper holes (thicker orifice plates) would lead to lower ED, and holes with larger diameter would lead to the higher ED in the same cross-sectional area, but in the same holes' diameters, higher cross-sectional area leads to the lower ED. The submerged operation mode showed a greater cavitational effects rather than the inline mode. Also, for the inline mode, the optimum value of 3 bar was obtained for the back-pressure condition in the system. Moreover, according to the analysis of changes in the UV-Vis spectra of RhB, both degradation of RhB chromophore structure and N-deethylation were occurred during the catalyzed HC process. Copyright © 2013 Elsevier B.V. All rights reserved.

Research on Cavitation Regions of Upstream Pumping Mechanical Seal Based on Dynamic Mesh Technique

Directory of Open Access Journals (Sweden)

Huilong Chen

2014-08-01

Full Text Available In order to study the cavitation area of the Upstream Pumping Mechanical Seal, three-dimensional microgap inner flow field of the Upstream Pumping Mechanical Seal was simulated with multiphase flow cavitation model and dynamic mesh technique based on hydrodynamic lubrication theory. Furthermore, the simulated result was compared with the experimental data. The results show that the simulated result with the Zwart-Gerber-Belamri cavitation model was much closer to the experimental data. The area of cavitation inception mainly occurred at the concave side of the spiral groove and surrounding region without spiral grooves, which was nearly covered by the inner diameter to roots of grooves; in addition, the region near the surface of the stationary ring was primary cavitation location. The area of cavitation has little relationship with the medium pressure; however, it became larger following increasing rotating speed in the range of researched operating conditions. Moreover the boundary of cavitated area was transformed from smooth to rough, which occurred in similar film thickness. When cavitation number was decreasing, which was conducive to improving the lubrication performance of sealed auxiliary, it made the sealing stability decline.

Flashback resistant pre-mixer assembly

Science.gov (United States)

Laster, Walter R [Oviedo, FL; Gambacorta, Domenico [Oviedo, FL

2012-02-14

A pre-mixer assembly associated with a fuel supply system for mixing of air and fuel upstream from a main combustion zone in a gas turbine engine. The pre-mixer assembly includes a swirler assembly disposed about a fuel injector of the fuel supply system and a pre-mixer transition member. The swirler assembly includes a forward end defining an air inlet and an opposed aft end. The pre-mixer transition member has a forward end affixed to the aft end of the swirler assembly and an opposed aft end defining an outlet of the pre-mixer assembly. The aft end of the pre-mixer transition member is spaced from a base plate such that a gap is formed between the aft end of the pre-mixer transition member and the base plate for permitting a flow of purge air therethrough to increase a velocity of the air/fuel mixture exiting the pre-mixer assembly.

Numerical solution for gate induced vibration due to under flow cavitation

International Nuclear Information System (INIS)

Sadrnezhad, S. A.

2001-01-01

Among the many forces to which hydraulic structures are exposed to, the forces induced by cavitation incident are of typical hydrodynamic unknown forces. The aim of this study is to define these forces as coupled fluid-structure interaction under two dynamic effects. The first dynamic effect which incorporates facilities for dealing with cavitation fluid is based on the appearance and bursting of vapor bubbles. The second hydrodynamic effect is dynamic excitation mechanism of the structure. In fluid-structure interaction, both the structure behavior and fluid are considered linear. Fluids can take some tension the extent of which depends on concentration and size of micro bubbles present; nevertheless, if the absolute pressure drops to a value close to the vapor pressure of the fluid, bubbles are formed and cavitation phenomena occurs. In this paper a fixed-wheel gate under the head pressure of a reservoir is considered to be affected by under flow cavitation. Normally, partially opened gates induce energy dissipation resulting in high turbulence, causing negative pressure and cavitation at the back and this exits the gate vibration. Moreover, there are several mechanisms which may cause heavy, self-excited vibration. According to the proposed method, a time function presenting the oscillation and pressure fluctuation in the vicinity of gate lip is estimated. This estimation is based on the parameters obtained from a two dimensional solution of flow under the gate lip. Accordingly, periodic time variable nodal forces are calculated and applied to gate lip element nodes. A transient dynamic solution of the gate, while its lip is sustaining nodal forces is estimated as time function. The results for the most server modal deformation of the structure time history of some critical elements and variation of equivalent force versus time are presented

Background nuclei measurements and implications for cavitation inception in hydrodynamic test facilities

Science.gov (United States)

Venning, J. A.; Khoo, M. T.; Pearce, B. W.; Brandner, P. A.

2018-04-01

Water susceptibility and background nuclei content in a water tunnel are investigated using a cavitation susceptibility meter. The measured cumulative histogram of nuclei concentration against critical pressure shows a power law dependence over a large range of concentrations and pressures. These results show that the water strength is not characterised by a single tension but is susceptible to `all' tensions depending on the relevant timescale. This background nuclei population is invariant to tunnel conditions showing that it is stabilised against dissolution. Consideration of a practical cavitating flow about a sphere shows that although background nuclei may be activated, their numbers are so few compared with other sources that they are insignificant for this case.

Steady State Thermo-Hydrodynamic Analysis of Two-Axial groove and Multilobe Hydrodynamic Bearings

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C. Bhagat

2014-12-01

Full Text Available Steady state thermo-hydrodynamic analysis of two axial groove and multi lobe oil journal bearings is performed in this paper. To study the steady state thermo-hydrodynamic characteristics Reynolds equation is solved simultaneously along with the energy equation and heat conduction equation in bush and shaft. The effect of groove geometry, cavitation in the fluid film, the recirculation of lubricant, shaft speed has also been taken into account. Film temperature in case of three-lobe bearing is found to be high as compared to other studied bearing configurations. The data obtained from this analysis can be used conveniently in the design of such bearings, which are presented in dimensionless form.

Hydrodynamic optical soliton tunneling

Science.gov (United States)

Sprenger, P.; Hoefer, M. A.; El, G. A.

2018-03-01

A notion of hydrodynamic optical soliton tunneling is introduced in which a dark soliton is incident upon an evolving, broad potential barrier that arises from an appropriate variation of the input signal. The barriers considered include smooth rarefaction waves and highly oscillatory dispersive shock waves. Both the soliton and the barrier satisfy the same one-dimensional defocusing nonlinear Schrödinger (NLS) equation, which admits a convenient dispersive hydrodynamic interpretation. Under the scale separation assumption of nonlinear wave (Whitham) modulation theory, the highly nontrivial nonlinear interaction between the soliton and the evolving hydrodynamic barrier is described in terms of self-similar, simple wave solutions to an asymptotic reduction of the Whitham-NLS partial differential equations. One of the Riemann invariants of the reduced modulation system determines the characteristics of a soliton interacting with a mean flow that results in soliton tunneling or trapping. Another Riemann invariant yields the tunneled soliton's phase shift due to hydrodynamic interaction. Soliton interaction with hydrodynamic barriers gives rise to effects that include reversal of the soliton propagation direction and spontaneous soliton cavitation, which further suggest possible methods of dark soliton control in optical fibers.

Hydrodynamics automatic optimization of runner blades for reaction hydraulic turbines

Science.gov (United States)

Balint, D.; Câmpian, V.; Nedelcu, D.; Megheles, O.

2012-11-01

The aim of this paper is to optimize the hydrodynamics of the runner blades of hydraulic turbines. The runner presented is an axial Kaplan one, but the methodology is common also to Francis runners. The whole methodology is implemented in the in-house software QTurbo3D. The effect of the runner blades geometry modification upon its hydrodynamics is shown both from energetic and cavitation points of view.

Hydrodynamics automatic optimization of runner blades for reaction hydraulic turbines

International Nuclear Information System (INIS)

Balint, D; Câmpian, V; Nedelcu, D; Megheles, O

2012-01-01

The aim of this paper is to optimize the hydrodynamics of the runner blades of hydraulic turbines. The runner presented is an axial Kaplan one, but the methodology is common also to Francis runners. The whole methodology is implemented in the in-house software QTurbo3D. The effect of the runner blades geometry modification upon its hydrodynamics is shown both from energetic and cavitation points of view.

Treatment of persistent organic pollutants in wastewater using hydrodynamic cavitation in synergy with advanced oxidation process.

Science.gov (United States)

Badmus, Kassim Olasunkanmi; Tijani, Jimoh Oladejo; Massima, Emile; Petrik, Leslie

2018-03-01

Persistent organic pollutants (POPs) are very tenacious wastewater contaminants. The consequences of their existence have been acknowledged for negatively affecting the ecosystem with specific impact upon endocrine disruption and hormonal diseases in humans. Their recalcitrance and circumvention of nearly all the known wastewater treatment procedures are also well documented. The reported successes of POPs treatment using various advanced technologies are not without setbacks such as low degradation efficiency, generation of toxic intermediates, massive sludge production, and high energy expenditure and operational cost. However, advanced oxidation processes (AOPs) have recently recorded successes in the treatment of POPs in wastewater. AOPs are technologies which involve the generation of OH radicals for the purpose of oxidising recalcitrant organic contaminants to their inert end products. This review provides information on the existence of POPs and their effects on humans. Besides, the merits and demerits of various advanced treatment technologies as well as the synergistic efficiency of combined AOPs in the treatment of wastewater containing POPs was reported. A concise review of recently published studies on successful treatment of POPs in wastewater using hydrodynamic cavitation technology in combination with other advanced oxidation processes is presented with the highlight of direction for future research focus.

Wastewater treatment using hybrid treatment schemes based on cavitation and Fenton chemistry: a review.

Science.gov (United States)

Bagal, Manisha V; Gogate, Parag R

2014-01-01

Advanced oxidation processes such as cavitation and Fenton chemistry have shown considerable promise for wastewater treatment applications due to the ease of operation and simple reactor design. In this review, hybrid methods based on cavitation coupled with Fenton process for the treatment of wastewater have been discussed. The basics of individual processes (Acoustic cavitation, Hydrodynamic cavitation, Fenton chemistry) have been discussed initially highlighting the need for combined processes. The different types of reactors used for the combined processes have been discussed with some recommendations for large scale operation. The effects of important operating parameters such as solution temperature, initial pH, initial pollutant concentration and Fenton's reagent dosage have been discussed with guidelines for selection of optimum parameters. The optimization of power density is necessary for ultrasonic processes (US) and combined processes (US/Fenton) whereas the inlet pressure needs to be optimized in the case of Hydrodynamic cavitation (HC) based processes. An overview of different pollutants degraded under optimized conditions using HC/Fenton and US/Fenton process with comparison with individual processes have been presented. It has been observed that the main mechanism for the synergy of the combined process depends on the generation of additional hydroxyl radicals and its proper utilization for the degradation of the pollutant, which is strongly dependent on the loading of hydrogen peroxide. Overall, efficient wastewater treatment with high degree of energy efficiency can be achieved using combined process operating under optimized conditions, as compared to the individual process. Copyright © 2013 Elsevier B.V. All rights reserved.

Optimization of hydrodynamic cavitations reactor efficiency for biodiesel production by response surface methods (Case study: Sunflower oil

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H Javadikia

2017-05-01

Full Text Available Introduction Biofuels are considered as one of the largest sources of renewable fuels or replacement of fossil fuels. Combustion of plant-based fuels is the indirect use of solar energy. Biofuels significantly have less pollution than other fossil fuels and can easily generate from residual plant material. Waste and residues of foods and wastewater can also be a good source for biofuel production. Transesterification method (one of biodiesel production methods is the most common forms to produce mono-alkyl esters from vegetable oil and animal fats. The procedure aims are reduction the oil viscosity during the reaction between triglycerides and alcohol in the presence of a catalyst or without it. In this study, the method of transesterification with alkaline catalysts is used that it is the most common and most commercial biodiesel production method. In this study, configurations of made hydrodynamic cavitation reactor were studied to measure biodiesel fuel quality and enhanced device performance with optimum condition. The Design Expert software and response surface methodology were used to get this purpose. Materials and Methods Transesterification method was used in this study. The procedure aims were reduction of the oil viscosity during the reaction between triglycerides and alcohol in the presence of a catalyst or without it. Materials needed in the production of biodiesel transesterification method include: vegetable oil, alcohol and catalysts. The used oil in the production of biodiesel was sunflower oil, which was used 0.6 liters per each test in the production process base on titration method. Methanol with purity of 99.8 percent and the molar ratio of 6:1 to oil was used based on titration equation and according to the results of other researchers. The used catalyst in continuous production process was high-purity sodium hydroxide (99% that it is one of alkaline catalysts. Weight of hydroxide was 1% of the used oil weight in the

Modeling cavitation in a rapidly changing pressure field - application to a small ultrasonic horn.

Science.gov (United States)

Žnidarčič, Anton; Mettin, Robert; Dular, Matevž

2015-01-01

Ultrasonic horn transducers are frequently used in applications of acoustic cavitation in liquids. It has been observed that if the horn tip is sufficiently small and driven at high amplitude, cavitation is very strong, and the tip can be covered entirely by the gas/vapor phase for longer time intervals. A peculiar dynamics of the attached cavity can emerge with expansion and collapse at a self-generated frequency in the subharmonic range, i.e. below the acoustic driving frequency. The term "acoustic supercavitation" was proposed for this type of cavitation Žnidarčič et al. (2014) [1]. We tested several established hydrodynamic cavitation models on this problem, but none of them was able to correctly predict the flow features. As a specific characteristic of such acoustic cavitation problems lies in the rapidly changing driving pressures, we present an improved approach to cavitation modeling, which does not neglect the second derivatives in the Rayleigh-Plesset equation. Comparison with measurements of acoustic supercavitation at an ultrasonic horn of 20kHz frequency revealed a good agreement in terms of cavity dynamics, cavity volume and emitted pressure pulsations. The newly developed cavitation model is particularly suited for simulation of cavitating flow in highly fluctuating driving pressure fields. Copyright © 2014 Elsevier B.V. All rights reserved.

PIV in the two phases of hydrodynamic cavitation in a venturi type section

Science.gov (United States)

Fuzier, Sylvie; Coudert, Sébastien; Coutier Delgosha, Olivier

2012-11-01

The presence of cavitation can affect the performance of turbomachinery. Attached sheet cavities on the blades induce modifications of flow dynamics and turbulence properties. This phenomenon is studied here in a configuration of 2D flow in a venturi type section. Images of the bubbles as well as of the light emitted by fluorescent particles placed in the liquid are recorded simultaneously. Velocities of the bubbles and of the liquid phase are obtained by PIV. The slip velocity is analyzed function of the number of cavitation and other physical parameters. Different levels of turbulence are correlated with different bubble structures in the dipahasic cavity.

Hydrodynamic cavitation characteristics of an orifice system and its effects on CRUD-like SiC deposition

International Nuclear Information System (INIS)

Kim, Seong Man; Bang, In Cheol

2016-01-01

Highlights: • CRUD-like SiC deposition was prepared for examining the erosion test in the cavitation field. • We investigated the comparison between swirl flow and common flow on cavitation. • Magnitude of shock pressure was investigated at low cavitation number. - Abstract: In a nuclear power plant, chalk river unidentified deposit (CRUD) is known as a deposit that is composed of corrosion and oxidation materials. It has a porous structure, which combines with boron that is injected into the coolant for controlling power levels. The buildup of corrosion products on the fuel cladding surface has proven to be particularly significant for both BWRs and PWRs. The high temperature of the cladding surface attracts impurities and chemical additives in the reactor coolant that deposit on the fuel rod surface in a process. The deposits on a fuel rod, known as CRUD, can be tenacious, insulative compounds capable of increasing the local clad temperature and accelerating clad corrosion—sometimes to the point of fuel failure. The deposition of CRUD on fuel cladding surfaces causes uneven heating of the reactor core. The situation is exacerbated by boron, which is added to the coolant to control power levels. However, boron becomes concentrated and is deposited within thick CRUD deposits. Ultrasonic mechanisms were developed but they have limitations for decontamination. In this experiment, a decontamination test was conducted using a sample sheet that was composed of SiC/water nanofluids. In addition, it was exposed to swirl flow and common flow for checking enhanced cavitation. It is measured by a pressure film, as shock pressure is associated with cavitation number. As a pressure film is wetted easily in water, it was injected into a holder. In the experiment, the maximum shock pressure was obtained during swirl flow at a low cavitation number. This indicates that pressure was concentrated on the pressure film. Consequently, cavitation can get rid of CRUD layers

A novel device for hazardous substances degradation based on double-cavitating-jets impingement: Parameters optimization and efficiency assessment.

Science.gov (United States)

Tao, Yuequn; Cai, Jun; Huai, Xiulan; Liu, Bin

2017-08-05

Hydrodynamic cavitation is an effective advanced oxidation process. But sometimes it cannot obtain satisfactory treatment efficiency by using hydrodynamic cavitation individually, so it is necessary to introduce intensive methods. Based on double-cavitating-jets impingement, this paper presents a novel device that has advantages of strong heat and mass transfer and efficient chemical reactions. Based on the device, a series of experimental investigations on degradation of a basic dye, i.e. Rhodamine B were carried out. Significant Rhodamine B removal from aqueous solution was observed during 2h treatment and the degradation reaction conformed to pseudo-first-order kinetics. The synergetic effects between double-cavitating-jets impingement and Fenton chemistry on simultaneous degradation of Rhodamine B were confirmed. Both single-variable experiments and orthogonal experiments were carried out to study the effects of initial hydrogen peroxide, ferrous sulfate and Rhodamine B concentrations and the optimum conditions were found out. Effects of jet inlet pressure in the range of 6-12MPa and solution pH value in the range of 2-8 were also investigated. The cavitation yield was evaluated to assess the energy efficiency. The present treatment scheme showed advantages in terms of reducing the demand of hydrogen peroxide concentration and enhancing the treatment efficiency in large scale operation. Copyright © 2017 Elsevier B.V. All rights reserved.

Experimental investigation of a cavitating backward-facing step flow

International Nuclear Information System (INIS)

Maurice, G; Djeridi, H; Barre, S

2014-01-01

The present study is the first part of global experimental work which is intended to produce a refined database of liquid and vapor phases and to improve CFD modeling of turbulent cavitating flows which can occur in rocket engine turbo-pump inducers. The purpose of the present experimental study is to get a better understanding of the dynamics of the liquid phase in a cavitating backward facing step flow and provide a refined database for the physical analysis of interaction between turbulence and cavitation. The backward facing step flow provides us a well-known test case to compare vortex dynamics and a realistic industrial configuration such as backflow in turbo machinery. Experiments were conducted in the hydrodynamic tunnel of CREMHyG at Grenoble,which was especially designed to study cavitating shear flows at high Reynolds numbers. To highlight the liquid phase topology and dynamics such as large vortex structures, free shear layer instability, reattachment wall interaction and reverse flow, the flow is characterized by Laser Induced Fluoresence Particles Image Velocimetry (PIV-LIF) measurements techniques and by Laser Doppler Velocimetry (LDV) techniques using spectral analysis to characterize the vortex shedding dynamics. The liquid phase was analyzed at different cavitation levels corresponding to 1% to 45% of void ratio range inside the shear layer, recirculation area and reattachment zone. The mean and fluctuating liquid velocities are clearly modified by the vapor phase and the scale of the vortical structures tends to be smaller inducing a destructuration of turbulence by cavitation

CAV-OX (trade name) Cavitation Oxidation Process Magnum Water Technology, Inc. applications analysis report. Report for November 1992-November 1993

Energy Technology Data Exchange (ETDEWEB)

Stacy, G.L.

1994-05-01

The CAV-OX process was developed by magnum Water Technology to destroy organic contaminants in water. The process uses hydrodynamic cavitation, ultraviolet (UV) radiation, and hydrogen peroxide to oxidize organic compounds present in water at or below milligrams per liter levels. This treatment technology produces no air emissions and generated no sludge or spent media that requires further processing, handling, or disposal. Ideally, the end products are water, carbon dioxide, halides, and in some cases, organic acids. The process uses mercury vapor lamps to generate UV radiation. The principal oxidants in the process, hydroxyl radicals, are produced by hydrodynamic cavitation and direct photolysis of hydrogen peroxide at UV wavelengths.

The use of hydrodynamic disintegration as a means to improve anaerobic digestion of activated sludge

OpenAIRE

Machnicka, A; Grűbel, K; Suschka, J

2009-01-01

Disintegration by hydrodynamic cavitation has a positive effect on the degree and rate of sludge anaerobic digestion. By applying hydrodynamic disintegration the lysis of cells occurs in minutes instead of days. The intracellular and extracellular components are set free and are immediately available for biological degradation which leads to an improvement of the subsequent anaerobic process. Hydrodynamic disintegration of the activated sludge results in organic matter and a polymer transfer ...

The Enhancement of H2O2/UV AOPs for the Removal of Selected Organic Pollutants from Drinking Water with Hydrodynamic Cavitation.

Science.gov (United States)

Čehovin, Matej; Medic, Alojz; Kompare, Boris; Žgajnar Gotvajn, Andreja

2016-12-01

Drinking water contains organic matter that occasionally needs to be treated to assure its sufficient quality and safety for the consumers. H2O2 and UV advanced oxidation processes (H2O2/UV AOPs) were combined with hydrodynamic cavitation (HC) to assess the effects on the removal of selected organic pollutants. Water samples containing humic acid, methylene blue dye and micropollutants (metaldehyde, diatrizoic acid, iohexol) were treated first by H2O2 (dosages from 1 to 12 mg L-1) and UV (dosages from 300 to 2800 mJ cm-2) AOPs alone and later in combination with HC, generated by nozzles and orifice plates (4, 8, 18 orifices). Using HC, the removal of humic acid was enhanced by 5-15%, methylene blue by 5-20% and metaldehyde by approx. 10%. Under favouring conditions, i.e. high UV absorbance of the matrix (more than 0.050 cm-1 at a wavelength of 254 nm) and a high pollutant to oxidants ratio, HC was found to improve the hydrodynamic conditions in the photolytic reactor, to improve the subjection of the H2O2 to the UV fluence rate distribution and to enhance the removal of the tested organic pollutants, thus showing promising potential of further research in this field.

Computational Fluid Dynamics and Experimental Studies of a New Mixing Element in a Static Mixer as a Heat Exchanger

Directory of Open Access Journals (Sweden)

Konopacki Maciej

2015-03-01

Full Text Available The main aim of this work is to study the thermal efficiency of a new type of a static mixer and to analyse the flow and temperature patterns and heat transfer efficiency. The measurements were carried out for the static mixer equipped with a new mixing insert. The heat transfer enhancement was determined by measuring the temperature profiles on each side of the heating pipe as well as the temperature field inside the static mixer. All experiments were carried out with varying operating parameters for four liquids: water, glycerol, transformer oil and an aqueous solution of molasses. Numerical CFD simulations were carried out using the two-equation turbulence k-ω model, provided by ANSYS Workbench 14.5 software. The proposed CFD model was validated by comparing the predicted numerical results against experimental thermal database obtained from the investigations. Local and global convective heat transfer coefficients and Nusselt numbers were detrmined. The relationship between heat transfer process and hydrodynamics in the static mixer was also presented. Moreover, a comparison of the thermal performance between the tested static mixer and a conventional empty tube was carried out. The relative enhancement of heat transfer was characterised by the rate of relative heat transfer intensification.

A new approach for bioethanol production from sugarcane bagasse using hydrodynamic cavitation assisted-pretreatment and column reactors.

Science.gov (United States)

Terán Hilares, Ruly; Kamoei, Douglas Viana; Ahmed, Muhammad Ajaz; da Silva, Silvio Silvério; Han, Jong-In; Santos, Júlio César Dos

2018-05-01

Hydrodynamic cavitation (HC) was adopted to assist alkaline-hydrogen peroxide pretreatment of sugarcane bagasse (SCB). In the following condition: 0.29 M of NaOH, 0.78% (v/v) of H 2 O 2 , 9.95 min of process time and 3 bar of inlet pressure, 95.4% of digestibility of cellulosic fraction was achieved. To take the best use of the pretreated biomass, the overall process was intensified by way of employing a packed bed flow-through column reactor and thus enabling to handle a high solid loading of 20%, thereby leading to cellulose and hemicellulose conversions to 74.7% and 75%, respectively. In the fermentation step, a bubble column reactor was introduced to maximize ethanol production from the pretreated SCB by Scheffersomyces stipitis NRRL-Y7124, resulting in 31.50 g/L of ethanol, 0.49 g/g of ethanol yield and 0.68 g/L.h of productivity. All this showed that our HC-assisted NaOH-H 2 O 2 pretreatment strategy along with the process intensification approach might offer an option for SCB-based biorefineries. Copyright © 2018 Elsevier B.V. All rights reserved.

Microwave mixer technology and applications

CERN Document Server

Henderson, Bert

2013-01-01

Although microwave mixers play a critical role in wireless communication and other microwave applications employing frequency conversion circuits, engineers find that most books on this subject emphasize theoretical aspects, rather than practical applications. That's about to change with the forthcoming release of Microwave Mixer Technology and Applications. Based on a review of over one thousand patents on mixers and frequency conversion, authors Bert Henderson and Edmar Camargo have written a comprehensive book for mixer designers who want solid ideas for solving their own design challenges.

Numerical analysis of the effects of radiation heat transfer and ionization energy loss on the cavitation Bubble's dynamics

Science.gov (United States)

Mahdi, M.; Ebrahimi, R.; Shams, M.

2011-06-01

A numerical scheme for simulating the acoustic and hydrodynamic cavitation was developed. Bubble instantaneous radius was obtained using Gilmore equation which considered the compressibility of the liquid. A uniform temperature was assumed for the inside gas during the collapse. Radiation heat transfer inside the bubble and the heat conduction to the bubble was considered. The numerical code was validated with the experimental data and a good correspondence was observed. The dynamics of hydrofoil cavitation bubble were also investigated. It was concluded that the thermal radiation heat transfer rate strongly depended on the cavitation number, initial bubble radius and hydrofoil angle of attack.

Experimental Study of Cavitation in Laminar Flow

OpenAIRE

Croci , Kilian; Ravelet , Florent; ROBINET , Jean-Christophe; Danlos , Amélie

2017-01-01

An experimental setup has been especially developed in order to observe cavitation in laminar flows. Experiments have been carried out with a silicon oil of viscosity υ = 100cSt passing through a Venturi-type geometry with 18°/8° convergent/divergent angles respectively. The range of Reynolds numbers at the inlet section is between 350 and 1000. Two dynamic regimes are identified. They are characterized by two critical Reynolds numbers, induced by major hydrodynamic changes in the flow, in ad...

Development of an enzyme fluidized bed reactor equipped with static mixers: application to lactose hydrolysis in whey

Energy Technology Data Exchange (ETDEWEB)

Fauquex, P F; Flaschel, E; Renken, A

1984-01-01

Reactor operation with immobilized enzymes in fixed bed arrangement is often impaired due to the presence of finely divided solid matter, adsorbing substances or gas. The fluidized bed reactor would be applied in such cases owing to a limited pressure drop, a controlled voidage, and the avoidance of perforated plates for catalyst retention. Since enzymic reactions are often slow processes, catalysts of high external surface area should be provided together with sufficient time. However, classical fluidized beds suffer from hydrodynamic instability under these conditions. Therefore, a new reactor design was developed which used motionless mixers as internals. Fluidized bed reactors equipped with internals exhibit an outstanding hydrodynamic stability accompanied by an increase of the operating range in terms of flow rate by a factor of 4 compared to the classical fluidized bed. Results are presented, with emphasis on the backmixing and expansion characteristics. Various motionless mixers were investigated in columns of 39 and 150 mm in diameter. The fluidized bed equipped with internals was used for lactose hydrolysis in partially deproteinized whey. The lactase from Aspergillus niger immobilized on silica gel particles of 125-160 molm had a half-life of approximately 1 mo.

Formation of a cavitation cluster in the vicinity of a quasi-empty rupture

Science.gov (United States)

Bol'shakova, E. S.; Kedrinskiy, V. K.

2017-09-01

The presentation deals with one of the experimental and numerical models of a quasi-empty rupture in the magma melt. This rupture is formed in the liquid layer of a distilled cavitating fluid under shock loading within the framework of the problem formulation with a small electromagnetic hydrodynamic shock tube. It is demonstrated that the rupture is shaped as a spherical segment, which retains its topology during the entire process of its evolution and collapsing. The dynamic behavior of the quasi-empty rupture is analyzed, and the growth of cavitating nuclei in the form of the boundary layer near the entire rupture interface is found. It is shown that rupture implosion is accompanied by the transformation of the bubble boundary layer to a cavitating cluster, which takes the form of a ring-shaped vortex floating upward to the free surface of the liquid layer. A p-κ mathematical model is formulated, and calculations are performed to investigate the implosion of a quasi-empty spherical cavity in the cavitating liquid, generation of a shock wave by this cavity, and dynamics of the bubble density growth in the cavitating cluster by five orders of magnitude.

Removal of bacteria Legionella pneumophila, Escherichia coli, and Bacillus subtilis by (super)cavitation.

Science.gov (United States)

Šarc, Andrej; Kosel, Janez; Stopar, David; Oder, Martina; Dular, Matevž

2018-04-01

In sufficient concentrations, the pathogenic bacteria L. pneumophila can cause a respiratory illness that is known as the "Legionnaires" disease. Moreover, toxic Shiga strains of bacteria E. coli can cause life-threatening hemolytic-uremic syndrome. Because of the recent restrictions imposed on the usage of chlorine, outbreaks of these two bacterial species have become more common. In this study we have developed a novel rotation generator and its effectiveness against bacteria Legionella pneumophila and Escherichia coli was tested for various types of hydrodynamic cavitation (attached steady cavitation, developed unsteady cavitation and supercavitation). The results show that the supercavitation was the only effective form of cavitation. It enabled more than 3 logs reductions for both bacterial species and was also effective against a more persistent Gram positive bacteria, B. subtilis. The deactivation mechanism is at present unknown. It is proposed that when bacterial cells enter a supercavitation cavity, an immediate pressure drop occurs and this results in bursting of the cellular membrane. The new rotation generator that induced supercavitation proved to be economically and microbiologically far more effective than the classical Venturi section (super)cavitation. Copyright © 2017 Elsevier B.V. All rights reserved.

Cavitation studies in microgravity

Science.gov (United States)

Kobel, Philippe; Obreschkow, Danail; Farhat, Mohamed; Dorsaz, Nicolas; de Bosset, Aurele

The hydrodynamic cavitation phenomenon is a major source of erosion for many industrial systems such as cryogenic pumps for rocket propulsion, fast ship propellers, hydraulic pipelines and turbines. Erosive processes are associated with liquid jets and shockwaves emission fol-lowing the cavity collapse. Yet, fundamental understanding of these processes requires further cavitation studies inside various geometries of liquid volumes, as the bubble dynamics strongly depends the surrounding pressure field. To this end, microgravity represents a unique platform to produce spherical fluid geometries and remove the hydrostatic pressure gradient induced by gravity. The goal of our first experiment (flown on ESA's parabolic flight campaigns 2005 and 2006) was to study single bubble dynamics inside large spherical water drops (having a radius between 8 and 13 mm) produced in microgravity. The water drops were created by a micro-pump that smoothly expelled the liquid through a custom-designed injector tube. Then, the cavitation bubble was generated through a fast electrical discharge between two electrodes immersed in the liquid from above. High-speed imaging allowed to analyze the implications of isolated finite volumes and spherical free surfaces on bubble evolution, liquid jets formation and shock wave dynamics. Of particular interest are the following results: (A) Bubble lifetimes are shorter than in extended liquid volumes, which could be explain by deriving novel corrective terms to the Rayleigh-Plesset equation. (B) Transient crowds of micro-bubbles (smaller than 1mm) appeared at the instants of shockwaves emission. A comparison between high-speed visualizations and 3D N-particle simulations of a shock front inside a liquid sphere reveals that focus zones within the drop lead to a significantly increased density of induced cavitation. Considering shock wave crossing and focusing may hence prove crucially useful to understand the important process of cavitation erosion

Biodiesel Production from Waste Cooking Oil Using Hydrodinamic Cavitation

Directory of Open Access Journals (Sweden)

Muhammad Supardan

2013-04-01

Full Text Available The aim of this research was to study biodiesel production from low cost feedstock of waste cooking oil (WCO using hydrodynamic cavitation apparatus. A two-step processes esterification process and transesterification process using hydrodynamic cavitation for the production of biodiesel from WCO is presented. The first step is acid-catalyzed esteri-fication process for reducing free fatty acid (FFA content of WCO and followed by base-catalyzed transesterification process for converting WCO to biodiesel as the second step. The result of esterification process with methanol to oil molar ratio of 5 and temperature of 60 oC showed that the initial acid value of WCO of 3.9 mg KOH/g can be decreased to 1.81 mg KOH/g in 120 minutes. The highest yield of biodiesel in transesterification process of 89.4% obtained at reaction time of 150 minutes with methanol to oil molar ratio of 6. The biodiesel produced in the experiment was analyzed by gas chromatography-mass spectrometry (GC-MS, which showed that it mainly contained five fatty acid methyl esters. In addition, the properties of biodiesel showed that all of the fuel properties met the Indonesian National Standard (INS No. 04-7182-2006 for biodiesel. 

A Ffowcs Williams and Hawkings formulation for hydroacoustic analysis of propeller sheet cavitation

Science.gov (United States)

Testa, C.; Ianniello, S.; Salvatore, F.

2018-01-01

A novel hydroacoustic formulation for the prediction of tonal noise emitted by marine propellers in presence of unsteady sheet cavitation, is presented. The approach is based on the standard Ffowcs Williams and Hawkings equation and the use of transpiration (velocity and acceleration) terms, accounting for the time evolution of the vapour cavity attached on the blade surface. Drawbacks and potentialities of the method are tested on a marine propeller operating in a nonhomogeneous onset flow, by exploiting the hydrodynamic data from a potential-based panel method equipped with a sheet cavitation model and comparing the noise predictions with those carried out by an alternative numerical approach, documented in literature. It is shown that the proposed formulation yields a one-to-one correlation between emitted noise and sheet cavitation dynamics, carrying out accurate predictions in terms of noise magnitude and directivity.

Attached cavitation at a small diameter ultrasonic horn tip

Science.gov (United States)

Žnidarčič, Anton; Mettin, Robert; Cairós, Carlos; Dular, Matevž

2014-02-01

Ultrasonic horn transducers are frequently used in applications of acoustic cavitation in liquids, for instance, for cell disruption or sonochemical reactions. They are operated typically in the frequency range up to about 50 kHz and have tip diameters from some mm to several cm. It has been observed that if the horn tip is sufficiently small and driven at high amplitude, cavitation is very strong, and the tip can be covered entirely by the gas/vapor phase for longer time intervals. A peculiar dynamics of the attached cavity can emerge with expansion and collapse at a self-generated frequency in the subharmonic range, i.e., below the acoustic driving frequency. Here, we present a systematic study of the cavitation dynamics in water at a 20 kHz horn tip of 3 mm diameter. The system was investigated by high-speed imaging with simultaneous recording of the acoustic emissions. Measurements were performed under variation of acoustic power, air saturation, viscosity, surface tension, and temperature of the liquid. Our findings show that the liquid properties play no significant role in the dynamics of the attached cavitation at the small ultrasonic horn. Also the variation of the experimental geometry, within a certain range, did not change the dynamics. We believe that the main two reasons for the peculiar dynamics of cavitation on a small ultrasonic horn are the higher energy density on a small tip and the inability of the big tip to "wash" away the gaseous bubbles. Calculation of the somewhat adapted Strouhal number revealed that, similar to the hydrodynamic cavitation, values which are relatively low characterize slow cavitation structure dynamics. In cases where the cavitation follows the driving frequency this value lies much higher - probably at Str > 20. In the spirit to distinguish the observed phenomenon with other cavitation dynamics at ultrasonic transducer surfaces, we suggest to term the observed phenomenon of attached cavities partly covering the full horn

Superhigh Temperatures and Acoustic Cavitation

CERN Document Server

Belyaev, V B; Miller, M B; Sermyagin, A V; Topolnikov, A S

2003-01-01

The experimental results on thermonuclear synthesis under acoustic cavitation have been analyzed with the account of the latest data and their discussion. The analysis testifies that this avenue of research is a very promising one. The numerical calculations of the D(d, n)^{3}He reaction rate in the deuterated acetone (C_{3}D_{6}O) under the influence of ultrasound depending on T environment temperature within the range T=249-295 K have been carried out within the framework of hydrodynamic model. The results show that it is possible to improve substantially the effect/background relationship in experiments by decreasing the fluid temperature twenty-thirty degrees below zero.

Ethanol production in a simultaneous saccharification and fermentation process with interconnected reactors employing hydrodynamic cavitation-pretreated sugarcane bagasse as raw material.

Science.gov (United States)

Terán Hilares, Ruly; Ienny, João Vitor; Marcelino, Paulo Franco; Ahmed, Muhammad Ajaz; Antunes, Felipe A F; da Silva, Silvio Silvério; Santos, Júlio César Dos

2017-11-01

In this study, sugarcane bagasse (SCB) pretreated with alkali assisted hydrodynamic cavitation (HC) was investigated for simultaneous saccharification and fermentation (SSF) process for bioethanol production in interconnected column reactors using immobilized Scheffersomyces stipitis NRRL-Y7124. Initially, HC was employed for the evaluation of the reagent used in alkaline pretreatment. Alkalis (NaOH, KOH, Na 2 CO 3 , Ca(OH) 2 ) and NaOH recycled black liquor (successive batches) were used and their pretreatment effectiveness was assessed considering the solid composition and its enzymatic digestibility. In SSF process using NaOH-HC pretreatment SCB, 62.33% of total carbohydrate fractions were hydrolyzed and 17.26g/L of ethanol production (0.48g of ethanol/g of glucose and xylose consumed) was achieved. This proposed scheme of HC-assisted NaOH pretreatment together with our interconnected column reactors showed to be an interesting new approach for biorefineries. Copyright © 2017 Elsevier Ltd. All rights reserved.

Investigation of Two-Phase Flow in AxialCentrifugal Impeller by Hydrodynamic Modeling Methods

Directory of Open Access Journals (Sweden)

V. O. Lomakin

2014-01-01

Full Text Available The article provides a methodology to study the flow in the wet part of the pump with fundamentally new axial-centrifugal impeller by methods of hydrodynamic modeling in the software package STAR CCM +. The objective of the study was to determine the normal and cavitation characteristics of the pump with a new type of wet part, as well as optimization of the geometrical parameters of the pump. Authors solved this problem using an example of the hot coolant pump, which should meet high requirements for cavitation quality and efficiency (hydraulic efficiency up to 87%, critical value of NPSH to 2.2 m.Also, the article focuses on the methods of numerical solution of two-phase flow simulation in a pump that are needed for a more accurate simulation of cavitation in the pump and research work in liquids with high gas content.Hydrodynamic modeling was performed on a computing cluster at the department E-10 of BMSTU for pump flow simulation in unsteady statement of problem using the computational grid size to 1.5 million cells. Simultaneously, the experimental model of the pump was made by 3D printing and tested at the stand in the BMSTU. Test results, which were compared with the calculated data are also given in the article. Inaccuracy of the calculation of pump head does not exceed 5%.The simulation results may be of interest to specialists in the field of hydrodynamic modeling, and for designers of such pumps. The authors also report production of a full-length prototype of the pump in order to conduct further testing for the verification of the data in the article, primarily in terms of cavitation characteristics.

MM wave quasioptical SIS mixers

International Nuclear Information System (INIS)

Hu, Qing; Mears, C.A.; Richards, P.L.; Lloyd, F.L.

1988-08-01

We have tested the performance of planar SIS mixers with log-periodic antennas at near millimeter and submillimeter wave frequencies from 90 to 360 GHz. The large ωR/sub N/C product (/approximately/10 at 90 GHz) of our Nb/NbO/sub x//Pb-In-Au junctions requires an integrated inductive tuning element to resonate the junction capacitance at the operating frequencies. We have used two types of integrated tuning element, which were designed with the aid of measurements using a Fourier transform spectrometer. Preliminary results indicate that the tuning elements can give very good mixer performance up to at least 200 GHz. An inductive wire in parallel with a 5-junction array gives a minimum mixer noise temperature of 115K (DSB) at 90 GHz with a FWHM bandwidth of 8 GHz. An open-ended microstrip stub in parallel with a single junction, gives minimum mixer noise temperatures of 150 and 200K (DSB) near 90 and 180 GHz with FWHM bandwidths of 4 and 3 GHz, respectively. The relatively high mixer noise temperatures compared to those of waveguide SIS mixers in a similar frequency range are attributed mainly to the losses in our optical system, which is being improved. 13 refs., 6 figs., 1 tab

Synergetic pretreatment of waste activated sludge by hydrodynamic cavitation combined with Fenton reaction for enhanced dewatering.

Science.gov (United States)

Cai, Meiqiang; Hu, Jianqiang; Lian, Guanghu; Xiao, Ruiyang; Song, Zhijun; Jin, Micong; Dong, Chunying; Wang, Quanyuan; Luo, Dewen; Wei, Zongsu

2018-04-01

The dewatering of waste activated sludge by integrated hydrodynamic cavitation (HC) and Fenton reaction was explored in this study. We first investigated the effects of initial pH, sludge concentration, flow rate, and H 2 O 2 concentration on the sludge dewaterability represented by water content, capillary suction time and specific resistance to filtration. The results of dewatering tests showed that acidic pH and low sludge concentration were favorable to improve dewatering performance in the HC/Fenton system, whereas optimal flow rate and H 2 O 2 concentration applied depended on the system operation. To reveal the synergism of HC/Fenton treatment, a suite of analysis were implemented: three-dimensional excitation emission matrix (3-DEEM) spectra of extracellular polymeric substances (EPS) such as proteins and polysaccharides, zeta potential and particle size of sludge flocs, and SEM/TEM imaging of sludge morphology. The characterization results indicate a three-step mechanism, namely HC fracture of different EPS in sludge flocs, Fenton oxidation of the released EPS, and Fe(III) re-flocculation, that is responsible for the synergistically enhanced sludge dewatering. Results of current study provide a basis to improve our understanding on the sludge dewatering performance by HC/Fenton treatment and possible scale-up of the technology for use in wastewater treatment plants. Copyright © 2017 Elsevier B.V. All rights reserved.

Use of hydrodynamic disintegration to accelerate anaerobic digestion of surplus activated sludge.

Science.gov (United States)

Grübel, Klaudiusz; Machnicka, Alicja

2009-12-01

Hydrodynamic disintegration of activated sludge resulted in organic matter and polymers transfer from the solid phase into the liquid phase. Disintegration by hydrodynamic cavitation had a positive effect on the degree and rate of excess sludge anaerobic digestion. Also, addition of a part of anaerobic digested sludge containing adapted microorganisms resulted in acceleration of the process. The disruption of cells of foam microorganisms and addition to the digestion process led to an increase of biogas production.

Current knowledge and potential applications of cavitation technologies for the petroleum industry.

Science.gov (United States)

Avvaru, Balasubrahmanyam; Venkateswaran, Natarajan; Uppara, Parasuveera; Iyengar, Suresh B; Katti, Sanjeev S

2018-04-01

Technologies based on cavitation, produced by either ultrasound or hydrodynamic means, are part of growing literature for individual refinery unit processes. In this review, we have explained the mechanism through which these cavitation technologies intensify individual unit processes such as enhanced oil recovery, demulsification of water in oil emulsions during desalting stage, crude oil viscosity reduction, oxidative desulphurisation/demetallization, and crude oil upgrading. Apart from these refinery processes, applications of this technology are also mentioned for other potential crude oil sources such as oil shale and oil sand extraction. The relative advantages and current situation of each application/process at commercial scale is explained. Copyright © 2017 Elsevier B.V. All rights reserved.

Numerical simulation of 3-D incompressible, multi-phase flows over cavitating projectiles

Energy Technology Data Exchange (ETDEWEB)

Owis, F.M.; Nayfeh, A.H. [Blacksburg State University, Dept. of Engineering Science and Mechanics, MC 0219, Virginia Polytechnic Institute, VA (United States)

2004-04-01

The hydrodynamic cavitation over axisymmetric projectiles is computed using the unsteady incompressible Navier-Stokes equations for multi-fluid elements. The governing equations are discretized on a structured grid using an upwind difference scheme with flux limits. A preconditioning dual-time stepping method is used for the unsteady computations. The Eigen-system is derived for the Jacobian matrices. This Eigen-system is suitable for high-density ratio multi-fluid flows and it provides high numerical stability and fast convergence. This method can be used to compute single- as well as multi-phase flows. Cavitating flows over projectiles with different geometries are computed and the results are in good agreement with available experimental data and other published computations. (authors)

Scale-up of the mixer of a mixer-settler model used in a uranium solvent extraction process

International Nuclear Information System (INIS)

Santana, A.O. de; Dantas, C.C.

1995-01-01

Scale-up relations were obtained for the mixer of a box type mixer-settler used in an uranium extraction process from chloridric leaches. Three box type mixers of different sizes and with the same geometry were used for batch and continuous-flow experiments. The correlations between the extraction rate and he specific power input, D/T ratio(=turbine diameter/mixer width) and residence time were experimentally determined. The results showed that the extraction rate increases with the power input at a constant D/T ratio equal to 1/3, remaining however, independent from the mixer size for a specific value of the power input. This behaviour was observed for power input values ranging from 100 to 750 W/m 3 . (author) 8 refs.; 8 figs.; 4 tabs

On the hydrodynamics of rocket propellant engine inducers and turbopumps

International Nuclear Information System (INIS)

D'Agostino, L

2013-01-01

The lecture presents an overview of some recent results of the work carried out at Alta on the hydrodynamic design and rotordynamic fluid forces of cavitating turbopumps for liquid propellant feed systems of modern rocket engines. The reduced order models recently developed for preliminary geometric definition and noncavitating performance prediction of tapered-hub axial inducers and centrifugal turbopumps are illustrated. The experimental characterization of the rotordynamic forces acting on a whirling four-bladed, tapered-hub, variable-pitch high-head inducer, under different load and cavitation conditions is presented. Future perspectives of the work to be carried out at Alta in this area of research are briefly illustrated

Cavitation

CERN Document Server

Young, F Ronald

1999-01-01

First published by McGraw-Hill in 1989, this book provides a unified treatment of cavitation, a phenomenon which extends across the boundaries of many fields. The approach is wide-ranging and the aim is to give due consideration to the many aspects of cavitation in proportion to their importance. Particular attention is paid to the diverse situations in which cavitation occurs and to its practical applications.

Report of sodium cavitation

International Nuclear Information System (INIS)

Murai, Hitoshi; Shima, Akira; Oba, Toshisaburo; Kobayashi, Ryoji; Hashimoto, Hiroyuki

1975-01-01

The damage of components for LMFBRs due to sodium cavitation is serious problem. This report summarizes the following items, (1) mechanism of the incipience of sodium cavitation, (2) damage due to sodium cavitation, (3) detection method for sodium cavitation, and (4) estimation method for sodium cavitation by the comparison with water cavitation. Materials were collected from the reports on liquid metal cavitation, sodium cavitation and water cavitation published from 1965 to now. The mechanism of the incipience of sodium cavitation cavitation parameters (mean location, distributed amount or occurrence aspect and stability), experiment of causing cavitation with Venturi tube, and growth of bubbles within superheated sodium. The sodium cavitation damage was caused by magnetostriction vibration method and with Venturi tube. The state of damage was investigated with the cavitation performance of a sodium pump, and the damage was examined in view of the safety of LMFBR plants. Sodium cavitation was detected with acoustic method, radiation method, and electric method. The effect of physical property of liquid on incipient cavitation was studied. These are thermodynamic effect based on quasistatic thermal equilibrium condition and the effect of the physical property of liquid based on bubble dynamics. (Iwase, T.)

Microbubble Cavitation Imaging

Science.gov (United States)

Vignon, Francois; Shi, William T.; Powers, Jeffry E.; Everbach, E. Carr; Liu, Jinjin; Gao, Shunji; Xie, Feng; Porter, Thomas R.

2014-01-01

Ultrasound cavitation of microbubble contrast agents has a potential for therapeutic applications such as sonothrombolysis (STL) in acute ischemic stroke. For safety, efficacy, and reproducibility of treatment, it is critical to evaluate the cavitation state (moderate oscillations, stable cavitation, and inertial cavitation) and activity level in and around a treatment area. Acoustic passive cavitation detectors (PCDs) have been used to this end but do not provide spatial information. This paper presents a prototype of a 2-D cavitation imager capable of producing images of the dominant cavitation state and activity level in a region of interest. Similar to PCDs, the cavitation imaging described here is based on the spectral analysis of the acoustic signal radiated by the cavitating microbubbles: ultraharmonics of the excitation frequency indicate stable cavitation, whereas elevated noise bands indicate inertial cavitation; the absence of both indicates moderate oscillations. The prototype system is a modified commercially available ultrasound scanner with a sector imaging probe. The lateral resolution of the system is 1.5 mm at a focal depth of 3 cm, and the axial resolution is 3 cm for a therapy pulse length of 20 µs. The maximum frame rate of the prototype is 2 Hz. The system has been used for assessing and mapping the relative importance of the different cavitation states of a microbubble contrast agent. In vitro (tissue-mimicking flow phantom) and in vivo (heart, liver, and brain of two swine) results for cavitation states and their changes as a function of acoustic amplitude are presented. PMID:23549527

Determining the hydrodynamic indices of contractions

International Nuclear Information System (INIS)

Blagov, Eh.E.

2002-01-01

The new dependences, making it possible only by measuring the flow rate and pressure drop on the contraction device (CD) with the known geometry, including the regulatory organ, in the non-crisis mode of the turbulent flow to calculate all the hydrodynamic indices of this device, including the pressure reduction in the jet contraction, are obtained. This simplifies and accelerates the CD hydraulic tests of all types. The new methodology for determining the cavitation factual start on the CD is proposed [ru

Apparatus for controlled mixing in a high intensity mixer

International Nuclear Information System (INIS)

Crocker, Z.; Gupta, V.P.

1982-01-01

An apparatus and a process is disclosed for controlled mixing of a mixable material in a high intensity mixer. The system enables instantaneous, precise and continual monitoring of a batch in a high intensity mixer which heretofore could not be achieved. The process comprises the steps of feeding a batch of material into a high intensity mixer, agitating the batch in the mixer, monitoring batch temperature separately from mixer temperature and discharging the batch from the mixer when the batch temperature reaches a final predetermined level. The apparatus includes means for monitoring batch temperature in a high intensity mixer separately from mixer temperature, and means responsive to the batch temperature to discharge the batch when the batch temperature reaches a final predetermined level

Vibration mixer

Energy Technology Data Exchange (ETDEWEB)

Alekhin, S.A.; Chernov, V.S.; Denisenko, V.V.; Gorodnyanskiy, I.F.; Prokopov, L.I.; Tikhonov, Yu.P.

1983-01-01

The vibration mixer is proposed which contains a housing, vibration drive with rod installed in the upper part of the mixing mechanism made in the form of a hollow shaft with blades. In order to improve intensity of mixing and dispersion of the mud, the shaft with the blades is arranged on the rod of the vibrator and is equipped with a cam coupling whose drive disc is attached to the vibration rod. The rod is made helical, while the drive disc of the cam coupling is attached to the helical surface of the rod. In addition, the vibration mixer is equipped with perforated discs installed on the ends of the rods.

Topology optimization of microfluidic mixers

DEFF Research Database (Denmark)

Andreasen, Casper Schousboe; Gersborg, Allan Roulund; Sigmund, Ole

2009-01-01

This paper demonstrates the application of the topology optimization method as a general and systematic approach for microfluidic mixer design. The mixing process is modeled as convection dominated transport in low Reynolds number incompressible flow. The mixer performance is maximized by altering...

Microbubble Cavitation Imaging

OpenAIRE

Vignon, Francois; Shi, William T.; Powers, Jeffry E.; Everbach, E. Carr; Liu, Jinjin; Gao, Shunji; Xie, Feng; Porter, Thomas R.

2013-01-01

Ultrasound cavitation of microbubble contrast agents has a potential for therapeutic applications such as sonothrombolysis (STL) in acute ischemic stroke. For safety, efficacy, and reproducibility of treatment, it is critical to evaluate the cavitation state (moderate oscillations, stable cavitation, and inertial cavitation) and activity level in and around a treatment area. Acoustic passive cavitation detectors (PCDs) have been used to this end but do not provide spatial information.

Pre-design mixer-settler based on phase inversion

International Nuclear Information System (INIS)

Widiatmo, Djarot S.W

1998-01-01

The mixer settler was designed to extract uranium from organic phase by n-Dodecane and to separate heavy metal from liquid waste. The mixer settler was designed to save solvent without reducing the extraction efficiency. Extraction efficiency depend on : two phase dispersion on mixing, the type of droplet formation and completeness phase separation. The mixer settler has three main part i.e. mixer chamber, droplet formation device and phase inversion column. Mixer chamber was operated in laminar mixing, the total flow rate 200 ml.second -1 . The mixer chamber dimensions was 5 cm diameter and 7 cm height. It was completed with paddle mixer 3 cm diameter, 1 cm height and the speed rotation was 300 rpm. The droplet formation device was perforated plate 5 cm diameter with 1 mm holes. Phase Inversion column dimensions was 5 cm diameter and 50 cm height. (author)

Susceptibility of CANDU steam generator preheater to cavitation erosion

International Nuclear Information System (INIS)

Laroche, S.L.; Sun, L.; Pietralik, J.M.

2012-01-01

In 2009, Darlington Steam Generator (SG) tube inspections revealed some tubes had degraded in the preheater. The tube degradation occurred at the clearance gap between the tube and the preheater baffle and reached up to 50% through-wall depth at the baffles in the middle portion of the preheater. The general pattern of the damage and the elemental composition analysis suggested that the degradation was the result of a hydrodynamic process, such as cavitation erosion. Cavitation erosion occurs when vapour bubbles exist or form in the flowing liquid and then these bubbles collapse violently in the vicinity of the wall. These bubbles collapse when steam bubbles contact water that is sufficiently subcooled, below the saturation temperature. In the gap between the tube and the preheater baffle, low flow will exist due to the pressure difference across the baffle plate. In addition, heat transfer occurs from the primary-side fluid to the secondary-side fluid within this clearance gap that is driven by the primary-to-secondary temperature difference. Factors, such as the tube position in the baffle hole and fouling, influence the local conditions and can cause subcooled boiling that result in cavitation. This paper presents a study of flow and heat transfer phenomena to determine the factors contributing to cavitation erosion in SG preheaters. The analysis used the THIRST1 code for a 3-dimensional thermalhydraulic simulation of the steam generators and the ANSYS FLUENT®2 code for detailed calculations of flow and heat transfer in the clearance gaps. This study identifies that tubes in the preheater region are susceptible to cavitation erosion and indicates that this area should be part of the station inspection program because, regardless of preheater design, some tubes may experience the thermalhydraulic conditions and undergo degradations similar to those observed for the tubes in Darlington SGs. (author)

Forces and moments on a slender, cavitating body

Energy Technology Data Exchange (ETDEWEB)

Hailey, C.E.; Clark, E.L.; Buffington, R.J.

1988-01-01

Recently a numerical code has been developed at Sandia National Laboratories to predict the pitching moment, normal force, and axial force of a slender, supercavitating shape. The potential flow about the body and cavity is calculated using an axial distribution of source/sink elements. The cavity surface is assumed to be a constant pressure streamline, extending beyond the base of the model. Slender body approximation is used to model the crossflow for small angles of attack. A significant extension of previous work in cavitation flow is the inclusion of laminar and turbulent boundary layer solutions on the body. Predictions with this code, for axial force at zero angle of attack, show good agreement with experiments. There are virtually no published data availble with which to benchmark the pitching moment and normal force predictions. An experiment was designed to measure forces and moments on a supercavitation shape. The primary reason for the test was to obtain much needed data to benchmark the hydrodynamic force and moment predictions. Since the numerical prediction is for super cavitating shapes at very small cavitation numbers, the experiment was designed to be a ventilated cavity test. This paper describes the experimental procedure used to measure the pitching moment, axial and normal forces, and base pressure on a slender body with a ventilated cavity. Limited results are presented for pitching moment and normal force. 5 refs., 7 figs.

Review of parameters influencing the structural response of a submerged body under cavitation conditions

International Nuclear Information System (INIS)

Escaler, X; De La Torre, O; Farhat, M

2015-01-01

Submerged structures that operate under extreme flows are prone to suffer large scale cavitation attached to their surfaces. Under such conditions the added mass effects differ from the expected ones in pure liquids. Moreover, the existence of small gaps between the structure and surrounding bodies filled with fluid also influence the dynamic response. A series of experiments and numerical simulations have been carried out with a truncated NACA0009 hydrofoil mounted as a cantilever beam at the LMH-EPFL cavitation tunnel. The three first modes of vibration have been determined and analysed under various hydrodynamic conditions ranging from air and still water to partial cavitation and supercavitation. A remote nonintrusive excitation system with piezoelectric patches has been used for the experiments. The effects of the cavity properties and the lateral gap size on the natural frequencies and mode shapes have been determined. As a result, the significance of several parameters in the design of such structures is discussed. (paper)

Review of parameters influencing the structural response of a submerged body under cavitation conditions

Science.gov (United States)

Escaler, X.; De La Torre, O.; Farhat, M.

2015-12-01

Submerged structures that operate under extreme flows are prone to suffer large scale cavitation attached to their surfaces. Under such conditions the added mass effects differ from the expected ones in pure liquids. Moreover, the existence of small gaps between the structure and surrounding bodies filled with fluid also influence the dynamic response. A series of experiments and numerical simulations have been carried out with a truncated NACA0009 hydrofoil mounted as a cantilever beam at the LMH-EPFL cavitation tunnel. The three first modes of vibration have been determined and analysed under various hydrodynamic conditions ranging from air and still water to partial cavitation and supercavitation. A remote nonintrusive excitation system with piezoelectric patches has been used for the experiments. The effects of the cavity properties and the lateral gap size on the natural frequencies and mode shapes have been determined. As a result, the significance of several parameters in the design of such structures is discussed.

Mixer Assembly for a Gas Turbine Engine

Science.gov (United States)

Dai, Zhongtao (Inventor); Cohen, Jeffrey M. (Inventor); Fotache, Catalin G. (Inventor); Smith, Lance L. (Inventor); Hautman, Donald J. (Inventor)

2018-01-01

A mixer assembly for a gas turbine engine is provided, including a main mixer with fuel injection holes located between at least one radial swirler and at least one axial swirler, wherein the fuel injected into the main mixer is atomized and dispersed by the air flowing through the radial swirler and the axial swirler.

Low Voltage Current Mode Switched-Current-Mirror Mixer

Directory of Open Access Journals (Sweden)

Chunhua Wang

2009-09-01

Full Text Available A new CMOS active mixer topology can operate at 1 V supply voltage by use of SCM (switched currentmirror. Such current-mode mixer requires less voltage headroom with good linearization. Mixing is achieved with four improved current mirrors, which are alternatively activated. For ideal switching, the operation is equivalent to a conventional active mixer. This paper analyzes the performance of the SCM mixer, in comparison with the conventional mixer, demonstrating competitive performance at a lower supply voltage. Moreover, the new mixer’s die, without any passive components, is very small, and the conversion gain is easy to adjust. An experimental prototype was designed and simulated in standard chartered 0.18μm RF CMOS Process with Spectre in Cadence Design Systems. Experimental results show satisfactory mixer performance at 2.4 GHz.

Realization of THz Band Mixer Using Graphene

Directory of Open Access Journals (Sweden)

E. Ghasemi Mizuji

2014-05-01

Full Text Available In this article a new method for creating mixer component in infrared and THz is suggested. Since the nonlinear property of admittance creates frequency components that do not exist in the input signal and the electrical conductivity is associated with admittance, in our work we have proven and simulated that the nonlinear property of graphene admittance can produce mixer component. The simulation results show that the mixer component is larger than other components, therefore the mixer works properly. Because of nano scale of graphene structure, this method paves the road to achieve super compact circuits.

Experimental and numerical studies on super-cavitating flow of axisymmetric cavitators

Directory of Open Access Journals (Sweden)

Byoung-Kwon Ahn

2010-03-01

Full Text Available Recently underwater systems moving at high speed such as a super-cavitating torpedo have been studied for their practical advantage of the dramatic drag reduction. In this study we are focusing our attention on super-cavitating flows around axisymmetric cavitators. A numerical method based on inviscid flow is developed and the results for several shapes of the cavitator are presented. First using a potential based boundary element method, we find the shape of the cavitator yielding a sufficiently large enough cavity to surround the body. Second, numerical predictions of supercavity are validated by comparing with experimental observations carried out in a high speed cavitation tunnel at Chungnam National University (CNU CT.

Spare mitigation/retrieval mixer pumps

International Nuclear Information System (INIS)

Taylor, S.

1995-01-01

This document presents the functional design criteria for design, analysis, fabrication, testing, and installation of a waste tank mixer pump. The mixer pump will be operated to eliminate the periodic releases of large quantities of flammable gas (e.g., hydrogen) from Hanford Site waste tanks and also to accommodate retrieval of tank waste

A simple three-dimensional-focusing, continuous-flow mixer for the study of fast protein dynamics.

Science.gov (United States)

Burke, Kelly S; Parul, Dzmitry; Reddish, Michael J; Dyer, R Brian

2013-08-07

We present a simple, yet flexible microfluidic mixer with a demonstrated mixing time as short as 80 μs that is widely accessible because it is made of commercially available parts. To simplify the study of fast protein dynamics, we have developed an inexpensive continuous-flow microfluidic mixer, requiring no specialized equipment or techniques. The mixer uses three-dimensional, hydrodynamic focusing of a protein sample stream by a surrounding sheath solution to achieve rapid diffusional mixing between the sample and sheath. Mixing initiates the reaction of interest. Reactions can be spatially observed by fluorescence or absorbance spectroscopy. We characterized the pixel-to-time calibration and diffusional mixing experimentally. We achieved a mixing time as short as 80 μs. We studied the kinetics of horse apomyoglobin (apoMb) unfolding from the intermediate (I) state to its completely unfolded (U) state, induced by a pH jump from the initial pH of 4.5 in the sample stream to a final pH of 2.0 in the sheath solution. The reaction time was probed using the fluorescence of 1-anilinonaphthalene-8-sulfonate (1,8-ANS) bound to the folded protein. We observed unfolding of apoMb within 760 μs, without populating additional intermediate states under these conditions. We also studied the reaction kinetics of the conversion of pyruvate to lactate catalyzed by lactate dehydrogenase using the intrinsic tryptophan emission of the enzyme. We observe sub-millisecond kinetics that we attribute to Michaelis complex formation and loop domain closure. These results demonstrate the utility of the three-dimensional focusing mixer for biophysical studies of protein dynamics.

Hydrodynamic cavitation as a novel approach for pretreatment of oily wastewater for anaerobic co-digestion with waste activated sludge.

Science.gov (United States)

Habashi, Nima; Mehrdadi, Nasser; Mennerich, Artur; Alighardashi, Abolghasem; Torabian, Ali

2016-07-01

Application of hydrodynamic cavitation (HC) was investigated with the objective of biogas production enhancement from co-digestion of oily wastewater (OWW) and waste activated sludge (WAS). Initially, the effect of HC on the OWW was evaluated in terms of energy consumption and turbidity increase. Then, several mixtures of OWW (with and without HC pretreatment) and WAS with the same concentration of total volatile solid were prepared as a substrate for co-digestion. Following, several batch co-digestion trials were conducted. To compare the biogas production, a number of digestion trials were also conducted with a mono substrate (OWW or WAS alone). The best operating condition of HC was achieved in the shortest retention time (7.5 min) with the application of 3mm diameter orifice and maximum pump rotational speed. Biogas production from all co-digestion reactors was higher than the WAS mono substrate reactors. Moreover, biogas production had a direct relationship with OWW ratio and no major inhibition was observed in any of the reactors. The biogas production was also enhanced by HC pretreatment and almost all of the reactors with HC pretreatment had higher reaction rates than the reactors without pretreatment. Copyright © 2016 Elsevier B.V. All rights reserved.

Two-phase LMMHD mixer-development experiments

International Nuclear Information System (INIS)

Fabris, G.; Dunn, P.F.; Chow, J.C.F.

1978-01-01

The results of a series of experiments conducted to evaluate the fluid mechanical performance of various two-phase LMMHD mixer designs are presented. The results from both flow visualization studies of the local two-phase flows downstream from various mixer-element configurations and local measurements performed to characterize these flows are presented. A conceptual LMMHD mixer design is described that insures the generation of small bubbles, prevents the formation of gas slugs and separated regions, and favors the stabilization of a homogeneous foam flow

Experimental and numerical research on cavitating flows around axisymmetric bodies

International Nuclear Information System (INIS)

Haipeng, Wei; Song, Fu; Qin, Wu; Biao, Huang; Guoyu, Wang

2014-01-01

We investigated the cavitating flows around different axisymmetric bodies based on experiments and numerical simulation. In the numerical simulation, the multiphase Reynolds averaged Navier Stokes equations (RANS) were solved via the commercial computational fluid dynamics code CFX. The modified k-wSST turbulence model was used along with the transport equation-based cavitation model. In the experiments, a high-speed video technique was used to observe the unsteady cavitating flow patterns, and the dynamic force measurement system was used to measure the hydrodynamics of the axisymmetric bodies under different cavitation conditions. Results are shown for the hemisphere bodies, conical bodies and blunt bodies. Reasonable agreements were obtained between the computational and experimental results. The results show that for the hemispherical body, the cavity consists of quasi-steady transparent region and unsteady foggy water-vapor mixture region, which contains small-scale vortices and is dominated by bubble clusters, causing irregular disturbances at the cavity interfaces. The curvature at the front of the conical body is larger, resulting in that the flow separates at the shoulder of the axisymmetric body. The cavity stretches downstream and reaches to a fixed cavity length and shape. For blunt bodies, the incipient cavitation number is larger than that for the hemispherical body. A large cloud cavity is formed at the shoulder of the blunt body in the cores of vortices in high shear separation regions and the re-entrant jet does not significantly interact with the cavity interface when it moves upstream. As to the dynamic characteristics of unsteady cavitating flows around the axisymmetric bodies, the pulsation frequency for the hemispherical body is larger than that for the blunt body. For the hemispherical body, the pulsation is mainly caused by the high-frequency, small-scale shedding at the rear end of the cavity, while for the blunt body, the main factor for

Mechanism of cavitation damage and structure of a cavitating eddy

International Nuclear Information System (INIS)

Efimov, A.V.; Vorob'ev, G.A.; Filenko, Yu.I.; Petrov, K.N.

1976-01-01

As a result of experimental studies of the structure of a cavitating eddy and the action of single cavitation bubbles on a solid surface the assumption of double nature of cavitation damage forces depending on its regimes was made. The first type of the damage forces is shock waves, appearing around collapsing spherical bubble, the second type is hydraulic impacts of microjets making a hole in a collapsing aspherical bubble. The outward appearance of single microdents differs from each other. The damage of the first type is accompanied by corrosion. The cavitation erosion intensity of the damage of the first type exceeds that of the damage of the second type by one order of magnitude. The values of the porosity of a cavitation eddy, the bubble concentration and the distance between them, the bubble distribution according to the size and the form for the initial cavitation stage are given from holographic investigations

Hydrodynamic cavitation in combination with the ozone, hydrogen peroxide and the UV-based advanced oxidation processes for the removal of natural organic matter from drinking water.

Science.gov (United States)

Čehovin, Matej; Medic, Alojz; Scheideler, Jens; Mielcke, Jörg; Ried, Achim; Kompare, Boris; Žgajnar Gotvajn, Andreja

2017-07-01

Natural organic matter in drinking water is causing concern especially due to the formation of disinfection by-products (DBPs) by chlorine, as these are proven to have adverse health effects on consumers. In this research, humic acid was used as a source of dissolved organic carbon (DOC) in drinking water (up to 3mgL -1 ). The efficiency of DOC removal was studied by applying O 3 , H 2 O 2 /O 3 , H 2 O 2 /UV and O 3 /UV advanced oxidation processes (AOPs) alone and combined with hybrid hydrodynamic cavitation (HC), generated by an orifice plate, as this technology recently shows promising potential for the treatment of water, containing recalcitrant organic substances. It was observed that the combined treatment by HC could significantly affect the performance of the applied AOPs, with as little as 3-9 passes through the cavitation generators. For O 3 and H 2 O 2 dosages up to 2 and 4mgL -1 , respectively, and UV dosage up to 300mJcm -2 , HC enhanced DOC removal by 5-15% in all combinations, except for O 3 /UV AOPs. Overall, the potential benefits of HC for DOC removal were emphasized for low ratio between applied oxidants to DOC and high UV absorbance of the sample. Investigated DBPs formation potentials require special attention for H 2 O 2 /UV AOPs and combinations with HC. Copyright © 2017 Elsevier B.V. All rights reserved.

Fabrication and characterization of 8.87 THz schottky barrier mixer diodes for mixer

Science.gov (United States)

Wang, Wenjie; Li, Qian; An, Ning; Tong, Xiaodong; Zeng, Jianping

2018-04-01

In this paper we report on the fabrication and characterization of GaAs-based THz schottky barrier mixer diodes. Considering the analyzed results as well as fabrication cost and complexity, a group of trade-off parameters was determined. Electron-beam lithography and air-bridge technique have been used to obtain schottky diodes with a cut off frequency of 8.87 THz. Equivalent values of series resistance, ideal factor and junction capacitance of 10.2 (1) Ω, 1.14 (0.03) and 1.76(0.03) respectively have been measured for 0.7um diameter anode devices by DC and RF measurements. The schottky barrier diodes fabrication process is fully planar and very suitable for integration in THz frequency multiplier and mixer circuits. THz Schottky barrier diodes based on such technology with 2 μm diameter anodes have been tested at 1.6 THz in a sub-harmonic mixer.

Cavitation guide for control valves

Energy Technology Data Exchange (ETDEWEB)

Tullis, J.P. [Tullis Engineering Consultants, Logan, UT (United States)

1993-04-01

This guide teaches the basic fundamentals of cavitation to provide the reader with an understanding of what causes cavitation, when it occurs, and the potential problems cavitation can cause to a valve and piping system. The document provides guidelines for understanding how to reduce the cavitation and/or select control valves for a cavitating system. The guide provides a method for predicting the cavitation intensity of control valves, and how the effect of cavitation on a system will vary with valve type, valve function, valve size, operating pressure, duration of operation and details of the piping installation. The guide defines six cavitation limits identifying cavitation intensities ranging from inception to the maximum intensity possible. The intensity of the cavitation at each limit Is described, including a brief discussion of how each level of cavitation influences the valve and system. Examples are included to demonstrate how to apply the method, including making both size and pressure scale effects corrections. Methods of controlling cavitation are discussed providing information on various techniques which can be used to design a new system or modify an existing one so it can operate at a desired level of cavitation.

Cavitation guide for control valves

International Nuclear Information System (INIS)

Tullis, J.P.

1993-04-01

This guide teaches the basic fundamentals of cavitation to provide the reader with an understanding of what causes cavitation, when it occurs, and the potential problems cavitation can cause to a valve and piping system. The document provides guidelines for understanding how to reduce the cavitation and/or select control valves for a cavitating system. The guide provides a method for predicting the cavitation intensity of control valves, and how the effect of cavitation on a system will vary with valve type, valve function, valve size, operating pressure, duration of operation and details of the piping installation. The guide defines six cavitation limits identifying cavitation intensities ranging from inception to the maximum intensity possible. The intensity of the cavitation at each limit Is described, including a brief discussion of how each level of cavitation influences the valve and system. Examples are included to demonstrate how to apply the method, including making both size and pressure scale effects corrections. Methods of controlling cavitation are discussed providing information on various techniques which can be used to design a new system or modify an existing one so it can operate at a desired level of cavitation

Super-Cavitating Flow Around Two-Dimensional Conical, Spherical, Disc and Stepped Disc Cavitators

Science.gov (United States)

Sooraj, S.; Chandrasekharan, Vaishakh; Robson, Rony S.; Bhanu Prakash, S.

2017-08-01

A super-cavitating object is a high speed submerged object that is designed to initiate a cavitation bubble at the nose which extends past the aft end of the object, substantially reducing the skin friction drag that would be present if the sides of the object were in contact with the liquid in which the object is submerged. By reducing the drag force the thermal energy consumption to move faster can also be minimised. The super-cavitation behavioural changes with respect to Cavitators of various geometries have been studied by varying the inlet velocity. Two-dimensional computational fluid dynamics analysis has been carried out by applying k-ε turbulence model. The variation of drag coefficient, cavity length with respect to cavitation number and inlet velocity are analyzed. Results showed conical Cavitator with wedge angle of 30° has lesser drag coefficient and cavity length when compared to conical Cavitators with wedge angles 45° and 60°, spherical, disc and stepped disc Cavitators. Conical cavitator 60° and disc cavitator have the maximum cavity length but with higher drag coefficient. Also there is significant variation of supercavitation effect observed between inlet velocities of 32 m/s to 40 m/s.

Decolorization of Acid Orange 7 by an electric field-assisted modified orifice plate hydrodynamic cavitation system: Optimization of operational parameters.

Science.gov (United States)

Jung, Kyung-Won; Park, Dae-Seon; Hwang, Min-Jin; Ahn, Kyu-Hong

2015-09-01

In this study, the decolorization of Acid Orange 7 (AO-7) with intensified performance was obtained using hydrodynamic cavitation (HC) combined with an electric field (graphite electrodes). As a preliminary step, various HC systems were compared in terms of decolorization, and, among them, the electric field-assisted modified orifice plate HC (EFM-HC) system exhibited perfect decolorization performance within 40 min of reaction time. Interestingly, when H2O2 was injected into the EFM-HC system as an additional oxidant, the reactor performance gradually decreased as the dosing ratio increased; thus, the remaining experiments were performed without H2O2. Subsequently, an optimization process was conducted using response surface methodology with a Box-Behnken design. The inlet pressure, initial pH, applied voltage, and reaction time were chosen as operational key factors, while decolorization was selected as the response variable. The overall performance revealed that the selected parameters were either slightly interdependent, or had significant interactive effects on the decolorization. In the verification test, complete decolorization was observed under statistically optimized conditions. This study suggests that EFM-HC is a useful method for pretreatment of dye wastewater with positive economic and commercial benefits. Copyright © 2015 Elsevier B.V. All rights reserved.

Cavitation in Hydraulic Machinery

Energy Technology Data Exchange (ETDEWEB)

Kjeldsen, M.

1996-11-01

The main purpose of this doctoral thesis on cavitation in hydraulic machinery is to change focus towards the coupling of non-stationary flow phenomena and cavitation. It is argued that, in addition to turbulence, superimposed sound pressure fluctuations can have a major impact on cavitation and lead to particularly severe erosion. For the design of hydraulic devices this finding may indicate how to further limit the cavitation problems. Chapter 1 reviews cavitation in general in the context of hydraulic machinery, emphasizing the initial cavitation event and the role of the water quality. Chapter 2 discusses the existence of pressure fluctuations for situations common in such machinery. Chapter 3 on cavitation dynamics presents an algorithm for calculating the nucleation of a cavity cluster. Chapter 4 describes the equipment used in this work. 53 refs., 55 figs.,10 tabs.

A general numerical analysis of the superconducting quasiparticle mixer

Science.gov (United States)

Hicks, R. G.; Feldman, M. J.; Kerr, A. R.

1985-01-01

For very low noise millimeter-wave receivers, the superconductor-insulator-superconductor (SIS) quasiparticle mixer is now competitive with conventional Schottky mixers. Tucker (1979, 1980) has developed a quantum theory of mixing which has provided a basis for the rapid improvement in SIS mixer performance. The present paper is concerned with a general method of numerical analysis for SIS mixers which allows arbitrary terminating impedances for all the harmonic frequencies. This analysis provides an approach for an examination of the range of validity of the three-frequency results of the quantum mixer theory. The new method has been implemented with the aid of a Fortran computer program.

Diffusion-Cooled Tantalum Hot-Electron Bolometer Mixers

Science.gov (United States)

Skalare, Anders; McGrath, William; Bumble, Bruce; LeDuc, Henry

2004-01-01

A batch of experimental diffusion-cooled hot-electron bolometers (HEBs), suitable for use as mixers having input frequencies in the terahertz range and output frequencies up to about a gigahertz, exploit the superconducting/normal-conducting transition in a thin strip of tantalum. The design and operation of these HEB mixers are based on mostly the same principles as those of a prior HEB mixer that exploited the superconducting/normal- conducting transition in a thin strip of niobium and that was described elsewhere.

Improving biogas production from continuous co-digestion of oily wastewater and waste-activated sludge by hydrodynamic cavitation pre-treatment.

Science.gov (United States)

Habashi, Nima; Alighardashi, Abolghasem; Mennerich, Artur; Mehrdadi, Nasser; Torabian, Ali

2018-04-01

Hydrodynamic cavitation (HC) was evaluated as a pretreatment for synthetic oily wastewater (OWW) to be co-digested with waste-activated sludge (WAS). The main objective of the present research was the enhancement of biogas production by the application of HC pretreatment. HC was applied to the OWW, and the OWW and WAS were added to a 50 L continuous digestion reactor. As a control system, an identical digestion reactor was set up for co-digestion of the WAS and the OWW without pretreatment. The reactors were initially filled with inoculum and the hydraulic retention time (HRT) was set to 22 d. The HRT was gradually reduced to 19, 16, and finally 13 d, but the substrate quality was kept constant. The loading rate, accordingly, increased from 0.86 to 1.46 g TVS/(L d). The biogas volume was recorded online and its quality was analyzed regularly. The HC improved biogas production up to 43% at 22 d of HRT. Reducing the HRT decreased biogas production from the main reactor while that of the control reactor was more or less constant. HC also increased the biogas methane content; the methane concentration of the main reactor was about 3% higher than the methane concentration of the control reactor. The main reactor experienced no clogging or accumulation of fatty materials.

The Robust Control Mixer Module Method for Control Reconfiguration

DEFF Research Database (Denmark)

Yang, Z.; Blanke, M.

1999-01-01

into a LTI dynamical system, and furthermore multiple dynamical control mixer modules can be employed in our consideration. The H_{\\infty} control theory is used for the analysis and design of the robust control mixer modules. Finally, one practical robot arm system as benchmark is used to test the proposed......The control mixer concept is efficient in improving an ordinary control system into a fault tolerant one, especially for these control systems of which the real-time and on-line redesign of the control laws is very difficult. In order to consider the stability, performance and robustness...... of the reconfigurated system simultaneously, and to deal with a more general controller reconfiguration than the static feedback mechanism by using the control mixer approach, the robust control mixer module method is proposed in this paper. The form of the control mixer module extends from a static gain matrix...

Effects of ultrasonic and hydrodynamic cavitation on the treatment of cork wastewater by flocculation and Fenton processes.

Science.gov (United States)

Wu, Zhilin; Yuste-Córdoba, Francisco J; Cintas, Pedro; Wu, Zhansheng; Boffa, Luisa; Mantegna, Stefano; Cravotto, Giancarlo

2018-01-01

This paper reports that ultrasonic (US) and hydrodynamic cavitation (HC) are efficient strategies for the environmental remediation of cork wastewater (CW). It is necessary to remove toxic, inhibitory or refractory organic matter from CW using physical and chemical techniques (pre-treatment) prior to performing conventional biological treatment. After this biological treatment, it is also critical to further decontaminate (post-treatment) in order to meet the discharge limitation. The pre-treatment of diluted CW using Fenton oxidation (FE) alone led to COD and polyphenol (PP) removal values of 30% and 61%, respectively, while HC and US resulted in 83-90% increases in COD reduction and 26-33% increases in PP reduction. Whereas 55% and 91% COD and PP removal were achieved using flocculation (Floc) alone, COD elimination was increased by a further 7-18% under HC and US. No noticeable improvement in PP elimination was observed. US did not enhance the Floc decontamination of the original concentrated CW, however, considerable quantities of white biofilm were surprisingly generated on the CW surface after the pre-treatment, thus indicating the improvement of biodegradability of the resulting liquid. In fact, the post-treatment stage, using FE alone after having filtered the biofilms, led to reductions of 53% in COD and 90% in PP. The HC and US protocols resulted in 26-34% increases in COD elimination. HC further enhanced PP elimination caused by FE, while US resulted in lower levels of PP elimination. Copyright © 2017 Elsevier B.V. All rights reserved.

Schneiderian membrane detachment using transcrestal hydrodynamic ultrasonic cavitational sinus lift: a human cadaver head study and histologic analysis.

Science.gov (United States)

Troedhan, Angelo; Kurrek, Andreas; Wainwright, Marcel; Jank, Siegfried

2014-08-01

Recent studies have suggested the osteogenic layer of the periosteum at the base of the sinus membrane to play a key role in bone regeneration after sinus lift procedures. Thus, atraumatic detachment of the sinus membrane with an intact periosteum seems mandatory. The present histologic study of fresh human cadaver heads investigated the detachment behavior and histologic integrity of the detached periosteum after application of the transcrestal hydrodynamic ultrasonic cavitational sinus lift (tHUCSL-INTRALIFT). A total of 15 sinuses in 8 fresh human cadaver heads were treated using tHUCSL-INTRALIFT. After surgery, they were checked macroscopically for damage to the sinus membrane and then processed for histologic inspection under light microscopy. A total of 150 histologic specimens, randomly selected from the core surgical sites, were investigated using hematoxylin-eosin (HE), Azan, and trichrome staining. None of the 150 inspected specimens showed any perforation or dissection of the periosteum from the subepithelial connective tissue and respiratory epithelium and were fully detached from the bony antrum floor. The connecting Sharpey fibers revealed to be cleanly separated from the sinus floor in all specimens. The results of the present study suggest tHUCSL-INTRALIFT should be used to perform predictable and safe detachment of the periosteum from the bony sinus floor as a prerequisite for undisturbed and successful physiologic subantral bone regeneration. Copyright © 2014 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Work plan, AP-102 mixer pump removal and pump replacement

International Nuclear Information System (INIS)

Jimenez, R.F.

1994-01-01

The objective of this work plan is to plan the steps and estimate the costs required to remove the failed AP-102 mixer pump, and to plan and estimate the cost of the necessary design and specification work required to order a new, but modified, mixer pump including the pump and pump pit energy absorbing design. The main hardware required for the removal of the mixer is as follows: a flexible receiver and blast shield; a metal container for the pulled mixer pump; and a trailer and strongback to haul and manipulate the container. Additionally: a gamma scanning device will be needed to detect the radioactivity emanating from the mixer as it is pulled from the tank; a water spray system will be required to remove tank waste from the surface of the mixer as it is pulled from the AP-102 tank; and a lifting yoke to lift the mixer from the pump pit (the SY-101 Mixer Lifting Yoke will be used). A ''green house'' will have to be erected over the AP-102 pump pit and an experienced Hoisting and Rigging crew must be assembled and trained in mixer pump removal methods before the actual removal is undertaken

Scale effect on bubble growth and cavitation inception in cavitation susceptibility meters

International Nuclear Information System (INIS)

Shen, Y.T.; Gowing, S.

1985-01-01

The Reynolds number alone is not adequate to predict cavitation inception scaling. Recent experiments on headforms once again show that the cavitation inception data are very sensitive to the nuclei tensile strength which, in turn depends on the velocity scale. This paper theoretically investigates the influence of Reynolds number and velocity scale on cavitation inception in a cavitation susceptibility meter. The numerical examples given are based on a single bubble spherical model

Rayleigh-Plesset equation of the bubble stable cavitation in water: A nonequilibrium all-atom molecular dynamics simulation study

Science.gov (United States)

Man, Viet Hoang; Li, Mai Suan; Derreumaux, Philippe; Nguyen, Phuong H.

2018-03-01

The Rayleigh-Plesset (RP) equation was derived from the first principles to describe the bubble cavitation in liquids in terms of macroscopic hydrodynamics. A number of nonequilibrium molecular dynamics studies have been carried out to validate this equation in describing the bubble inertial cavitation, but their results are contradictory and the applicability of the RP equation still remains to be examined, especially for the stable cavitation. In this work, we carry out nonequilibrium all-atom simulation to validate the applicability of the RP equation in the description of the stable cavitation of nano-sized bubbles in water. We show that although microscopic effects are not explicitly included, this equation still describes the dynamics of subnano-bubbles quite well as long as the contributions of various terms including inertial, surface tension, and viscosity are correctly taken into account. These terms are directly and inversely proportional to the amplitude and period of the cavitation, respectively. Thus, their contributions to the RP equation depend on these two parameters. This may explain the discrepancy between the current results obtained using different parameters. Finally, the accuracy of the RP equation in the current mathematical modeling studies of the ultrasound-induced blood-brain-barrier experiments is discussed in some detail.

Magnetic Cavitation and the Reemergence of Nonlocal Transport in Laser Plasmas

International Nuclear Information System (INIS)

Ridgers, C. P.; Kingham, R. J.; Thomas, A. G. R.

2008-01-01

We present the first fully kinetic Vlasov-Fokker-Planck simulations of nanosecond laser-plasma interactions including self-consistent magnetic fields and hydrodynamic plasma expansion. For the largest magnetic fields externally applied to long-pulse laser-gas-jet experiments (12 T) a significant degree of cavitation of the B field (>40%) will be shown to occur from the laser-heated region in under half a nanosecond. This is due to the Nernst effect and leads to the reemergence of nonlocality even if the initial value of the magnetic field strength is sufficient to localize the transport

Cavitation noise from butterfly valves

International Nuclear Information System (INIS)

Rahmeyer, W.J.

1982-01-01

Cavitation in valves can produce levels of intense noise. It is possible to mathematically express a limit for a design level of cavitation noise in terms of the cavitation parameter sigma. Using the cavitation parameter or limit, it is then possible to calculate the flow conditions at which a design level of cavitation noise will occur. However, the intensity of cavitation increases with the upstream pressure and valve size at a constant sigma. Therefore, it is necessary to derive equations to correct or scale the cavitation limit for the effects of different upstream pressures and valve sizes. The following paper discusses and presents experimental data for the caviation noise limit as well as the cavitation limits of incipient, critical, incipient damage, and choking cavitation for butterfly valves. The main emphasis is on the design limit of caviation noise, and a noise level of 85 decibels was selected as the noise limit. Tables of data and scaling exponents are included for applying the design limits for the effects of upstream pressure and valve size. (orig.)

Supercritical fluid assisted production of chitosan oligomers micrometric powders.

Science.gov (United States)

Du, Zhe; Shen, Yu-Bin; Tang, Chuan; Guan, Yi-Xin; Yao, Shan-Jing; Zhu, Zi-Qiang

2014-02-15

Chitosan oligomers (O-chitosan) micrometric particles were produced from aqueous solution using a novel process, i.e. supercritical fluid assisted atomization introduced by hydrodynamic cavitation mixer (SAA-HCM). Hydrodynamic cavitation was introduced to enhance mass transfer and facilitate the mixing between SC-CO2 and liquid solution for fine particles formation. Well defined, separated and spherical microparticles were obtained, and the particles size could be well controlled with narrow distribution ranging from 0.5 μm to 3 μm. XRD patterns showed amorphous structure of O-chitosan microparticles. FTIR, TGA and DSC analyses confirmed that no change in molecular structure and thermal stability after SAA-HCM processing, while the water content was between 5.8% and 8.4%. Finally, tap densities were determined to be below 0.45 g/cm(3) indicating hollow or porous structures of microparticles. By tuning process parameters, theoretical mass median aerodynamic sizes lied inside respirable range of 1-2 μm, which presented the potential of the O-chitosan microparticles in application as inhaled dry powders. SAA-HCM was demonstrated to be very useful in particle size engineering. Copyright © 2013 Elsevier Ltd. All rights reserved.

Sustained release formulations of citronella oil nanoemulsion using cavitational techniques.

Science.gov (United States)

Agrawal, Naveen; Maddikeri, Ganesh L; Pandit, Aniruddha B

2017-05-01

Nanoemulsion synthesis has proven to be an effective way for transportation of immobile, insoluble bioactive compounds. Citronella Oil (lemongrass oil), a natural plant extract, can be used as a mosquito repellent and has less harmful effects compared to its available market counterpart DEET (N, N-Diethyl-meta-toluamide). Nanoemulsion of citronella oil in water was prepared using cavitation-assisted techniques while investigating the effect of system parameters like HLB (Hydrophilic Lipophilic Balance), surfactant concentration, input energy density and mode of power input on emulsion quality. The present work also examines the effect of emulsification on release rate to understand the relationship between droplet size and the release rate. Minimum droplet size (60nm) of the emulsion was obtained at HLB of 14, S/O 1 ratio of 1.0, ultrasound amplitude of 50% and irradiation time of 5min. This study revealed that hydrodynamic cavitation-assisted emulsification is more energy efficient compared to ultrasonic emulsification. It was also found that the release rate of nanoemulsion enhanced as the droplet size of emulsion reduced. Copyright © 2016 Elsevier B.V. All rights reserved.

21 CFR 888.4210 - Cement mixer for clinical use.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cement mixer for clinical use. 888.4210 Section... (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Surgical Devices § 888.4210 Cement mixer for clinical use. (a) Identification. A cement mixer for clinical use is a device consisting of a container intended for use in mixing...

On the mechanism of explosive eruption of mount erebus volcano: the dynamics of the rupture structure in a cavitating layer

International Nuclear Information System (INIS)

Bol'shakova, E S; Kedrinskiy, V K

2016-01-01

This paper presents the results of an experimental simulation of rupture development in heavily cavitating magma melt flow in volcanic conduits and its effect on the structure of explosive volcanic eruptions. The dynamics of the state of a layer of distilled water (similar in the density of cavitation nuclei to magma melt) under shock-wave loading was studied. The experiments were performed using electromagnetic hydrodynamic shock tubes (EM HST) with maximum capacitor bank energy of up to 100 J and 5 kJ. It was found that the topology of the rupture formed on the membrane surface did not change during its development. Empirical estimates were obtained for the proportion of the capacitor bank energy expended in the development of the rupture and the characteristic time of its existence. The study revealed a number of fundamentally new physical effects in the cavity dynamics in a cavitating medium: a cavitation “boundary layer” is formed on the surface of the quasi-empty rupture, which is transformed into a cluster of high energy density upon closure of the flow. (paper)

Micro-mixer/combustor

KAUST Repository

Badra, Jihad Ahmad; Masri, Assaad Rachid

2014-01-01

A micro-mixer/combustor to mix fuel and oxidant streams into combustible mixtures where flames resulting from combustion of the mixture can be sustained inside its combustion chamber is provided. The present design is particularly suitable

Scale-up of mixer-settler for uranium extraction

International Nuclear Information System (INIS)

Santana, A.O. de.

1990-05-01

The aim of this work was to obtain scale-up relations for a box type mixer-settler used in uranium extraction process for chloridric leaches. Three box type units with different sizes and with the same geometry were used for scale-up of the mixer. The correlation between extraction rate and specific power input, D/T ratio (stirrer diameter/mixer length) and residence time were experimentally obtained. The results showed that the extraction increases with power input for a constant value of D/T equal to 1/3, remaining however independent from mixer sizes for a specific value of power input. This behavior was observed for power input values ranging from 100 to 750 w/m 9 . (author). 23 refs, 22 figs, 23 tabs

INFLUENCE OF WATER-TO-CEMENT RATIO ON AIR ENTRAILMENT IN PRODUCTION OF NON-AUTOCLAVED FOAM CONCRETE USING TURBULENCE CAVITATION TECHNOLOGY

Directory of Open Access Journals (Sweden)

Gorshkov Pavel Vladimirovich

2012-10-01

Full Text Available Non-autoclaved foam concrete is an advanced thermal insulation material. Until recently, foam concrete production has been based on separate preparation of foam and solution, followed by their blending in a mixer. The situation changed when high-quality synthetic foaming agents and turbulence cavitation technology appeared on the market. Every model provides a dependence between the foam concrete strength and the water-to-cement ratio. According to the water-cement ratio we can distinguish strong concrete mixtures (with the water-to-cement ratio equal to 0.3…0.4 and ductile ones (with the water-to-cement ratio equal to 0.5…0.7. Strong concrete mixtures are more durable. The lower the water-to-cement ratio, the higher the foam concrete strength. However super-plastic substances cannot be mixed by ordinary turbulent mixers. Foam concrete produced using the turbulence cavitation technology needs air-entraining, its intensity being dependent on several factors. One of the main factors is the amount of free water, if it is insufficient, the mixture will not be porous enough. A researcher needs to identify the optimal water-to-cement ratio based on the water consumption rate. Practical production of prefabricated concrete products and structures has proven that the reduction of the water-to-cement ratio improves the strength of the product. The task is to find the water-to-cement ratio for the foam concrete mixture to be plastic enough for air entraining. An increase in the ratio causes loss in the strength. The ratio shall vary within one hundredth points. Super-plasticizers are an alternative solution.

Techniques of Ultrasound Cavitation Control

Directory of Open Access Journals (Sweden)

S. P. Skvortsov

2015-01-01

Full Text Available The control methods of ultrasonic cavitation applied now within the range from 20 kHz to 80 kHz use either control of ultrasound source parameters (amplitude, acoustic power, etc. or control of one of the cavitation effects (erosion of materials, sonoluminescence, power of acoustic noise, etc.. These methods provide effective management of technological processes, however, make it impossible to relate the estimated effect with parameters of pulsations of cavitation bubbles. This is, mainly, due to influence of a number of uncontrollable parameters, in particular, such as temperature, composition of liquid, gas content, etc. as well as because of the difficulty to establish interrelation between the estimated effect and parameters of pulsations. As a result, in most cases it is difficult to compare controlled parameters of ultrasonic cavitation among themselves, and quantitative characteristics of processes become depending on the type of ultrasonic installation and conditions of their measurement.In this regard, methods to determine parameters of bubble pulsations through sounding a cavitation area by low-intensity laser radiation or to record cavitation noise sub-harmonics reflecting dynamics of changing radius of cavitation bubbles are of interest. The method of optical sounding, via the analysis of spectral components of a scattered signal recorded by a photo-detector, allows us to define a phase of the bubbles collapse with respect to the sound wave and a moving speed of the bubbles wall, as well as to estimate a cavitation index within the light beam section.The method to record sub-harmonicas of cavitation noise allows us to define parameters of pulsations, average for cavitation areas.The above methods allow us both to study mechanisms of cavitation action and to form quantitative criteria of its efficiency based on the physical processes, rather than their consequences and are convenient for arranging a feedback in the units using

Combined experimental and computational investigation of the cavitating flow in an orifice plate with special emphasis on surrogate-based optimization method

International Nuclear Information System (INIS)

Li, XianLin; Huang, Biao; Chen, Tairan; Liu, Ying; Qiu, Si Cong; Zhao, Jing

2017-01-01

We investigated the influence of geometrical parameters of the orifice plate on the cavitation structures, and optimized these parameters by using a surrogate-based model with special emphasis on the concentration of hydroxyl radical released. The results show that for the orifice plate of the hydrodynamic cavitation system, the possible location of the inception of the cavity spreads to throat and divergent section of the venturi geometry. Based on the surrogate model and global sensitivity assessment, the diameter of throat Dt and diameter of inlet Din significantly influenced the size of the cavity, while the length of throat Lt had little effect on both cavitation intensity and flow rate. It should be noted that when Lt is decreased, the size of cavity would be slightly decreased but the flow rate increased clearly. The increase of the diverging section is in favor of the size of cavity. By comparing the experimental measurements on the concentration of Methylene blue, the optimum geometry of the orifice plate for best cavitational activity is proposed

Combined experimental and computational investigation of the cavitating flow in an orifice plate with special emphasis on surrogate-based optimization method

Energy Technology Data Exchange (ETDEWEB)

Li, XianLin; Huang, Biao; Chen, Tairan; Liu, Ying; Qiu, Si Cong [School of Mechanical and Vehicular Engineering, Beijing Institute of Technology, Beijing (China); Zhao, Jing [China Academy of Launch Vehicle Technology, Beijing (China)

2017-01-15

We investigated the influence of geometrical parameters of the orifice plate on the cavitation structures, and optimized these parameters by using a surrogate-based model with special emphasis on the concentration of hydroxyl radical released. The results show that for the orifice plate of the hydrodynamic cavitation system, the possible location of the inception of the cavity spreads to throat and divergent section of the venturi geometry. Based on the surrogate model and global sensitivity assessment, the diameter of throat Dt and diameter of inlet Din significantly influenced the size of the cavity, while the length of throat Lt had little effect on both cavitation intensity and flow rate. It should be noted that when Lt is decreased, the size of cavity would be slightly decreased but the flow rate increased clearly. The increase of the diverging section is in favor of the size of cavity. By comparing the experimental measurements on the concentration of Methylene blue, the optimum geometry of the orifice plate for best cavitational activity is proposed.

Modeling liquid hydrogen cavitating flow with the full cavitation model

Energy Technology Data Exchange (ETDEWEB)

Zhang, X.B.; Qiu, L.M.; Qi, H.; Zhang, X.J.; Gan, Z.H. [Institute of Refrigeration and Cryogenic Engineering, Zhejiang University, Hangzhou 310027 (China)

2008-12-15

Cavitation is the formation of vapor bubbles within a liquid where flow dynamics cause the local static pressure to drop below the vapor pressure. This paper strives towards developing an effective computational strategy to simulate liquid hydrogen cavitation relevant to liquid rocket propulsion applications. The aims are realized by performing a steady state computational fluid dynamic (CFD) study of liquid hydrogen flow over a 2D hydrofoil and an axisymmetric ogive in Hord's reports with a so-called full cavitation model. The thermodynamic effect was demonstrated with the assumption of thermal equilibrium between the gas phase and liquid phase. Temperature-dependent fluid thermodynamic properties were specified along the saturation line from the ''Gaspak 3.2'' databank. Justifiable agreement between the computed surface pressure, temperature and experimental data of Hord was obtained. Specifically, a global sensitivity analysis is performed to examine the sensitivity of the turbulent computations to the wall grid resolution, wall treatments and changes in model parameters. A proper near-wall model and grid resolution were suggested. The full cavitation model with default model parameters provided solutions with comparable accuracy to sheet cavitation in liquid hydrogen for the two geometries. (author)

An Anticipatory Model of Cavitation

Energy Technology Data Exchange (ETDEWEB)

Allgood, G.O.; Dress, W.B., Jr.; Hylton, J.O.; Kercel, S.W.

1999-04-05

The Anticipatory System (AS) formalism developed by Robert Rosen provides some insight into the problem of embedding intelligent behavior in machines. AS emulates the anticipatory behavior of biological systems. AS bases its behavior on its expectations about the near future and those expectations are modified as the system gains experience. The expectation is based on an internal model that is drawn from an appeal to physical reality. To be adaptive, the model must be able to update itself. To be practical, the model must run faster than real-time. The need for a physical model and the requirement that the model execute at extreme speeds, has held back the application of AS to practical problems. Two recent advances make it possible to consider the use of AS for practical intelligent sensors. First, advances in transducer technology make it possible to obtain previously unavailable data from which a model can be derived. For example, acoustic emissions (AE) can be fed into a Bayesian system identifier that enables the separation of a weak characterizing signal, such as the signature of pump cavitation precursors, from a strong masking signal, such as a pump vibration feature. The second advance is the development of extremely fast, but inexpensive, digital signal processing hardware on which it is possible to run an adaptive Bayesian-derived model faster than real-time. This paper reports the investigation of an AS using a model of cavitation based on hydrodynamic principles and Bayesian analysis of data from high-performance AE sensors.

Influence of cavitation bubble growth by rectified diffusion on cavitation-enhanced HIFU

Science.gov (United States)

Okita, Kohei; Sugiyama, Kazuyasu; Takagi, Shu; Matsumoto, Yoichiro

2017-11-01

Cavitation is becoming increasingly important in therapeutic ultrasound applications such as diagnostic, tumor ablation and lithotripsy. Mass transfer through gas-liquid interface due to rectified diffusion is important role in an initial stage of cavitation bubble growth. In the present study, influences of the rectified diffusion on cavitation-enhanced high-intensity focused ultrasound (HIFU) was investigated numerically. Firstly, the mass transfer rate of gas from the surrounding medium to the bubble was examined as function of the initial bubble radius and the driving pressure amplitude. As the result, the pressure required to bubble growth was decreases with increasing the initial bubble radius. Next, the cavitation-enhanced HIFU, which generates cavitation bubbles by high-intensity burst and induces the localized heating owing to cavitation bubble oscillation by low-intensity continuous waves, was reproduced by the present simulation. The heating region obtained by the simulation is agree to the treatment region of an in vitro experiment. Additionally, the simulation result shows that the localized heating is enhanced by the increase of the equilibrium bubble size due to the rectified diffusion. This work was supported by JSPS KAKENHI Grant Numbers JP26420125,JP17K06170.

Research of UHPC properties prepared with industrial mixer

Science.gov (United States)

Šerelis, E.; Vaitkevičius, V.; Kerševičius, V.

2017-09-01

Ultra-high performance concrete (UHPC) mixture with advanced mechanical and durability properties was created using decent Zyklos ZZ50HE mixer. Zyklos ZZ50HE rotating pan mixer is similar to mixer which has common concrete plants. In experiment UHPC was prepared with Zyklos ZZ50HE mixer and thereafter best composition was selected and prepared with industrial HPGM 1125 mixer. Experiment results revealed that UHPC with W/C=0.29 and advanced mechanical and durability properties can be prepared. In experiment tremendous amount of micro steel fibres (up to 147 kg/m3) were incorporated in UHPC. Concrete with excellent salt scaling resistance and great mechanical properties was obtained. Compressive strength was increased about 30 % from 116 MPa to 150 MPa and flexural strength was increased about 5 times from 6.7 to 36.2 MPa. Salt-scaling resistance at 40 cycles in 3 % NaCl solution varied from 0.006 kg/m2 to 0.197 kg/m2. There were a few attempts to create UHPC and UHPFRC with decent technology, however, unsuccessfully till now. In the world practice this new material is currently used in the construction of bridges and viaducts.

Overview of Rotating Cavitation and Cavitation Surge in the Fastrac Engine LOX Turbopump

Science.gov (United States)

Zoladz, Thomas; Turner, Jim (Technical Monitor)

2001-01-01

Observations regarding rotating cavitation and cavitation surge experienced during the development of the Fastrac 60 Klbf engine turbopump are discussed. Detailed observations from the analysis of both water flow and liquid oxygen test data are offered. Scaling and general comparison of rotating cavitation between water flow and liquid oxygen testing are discussed. Complex data features linking the localized rotating cavitation mechanism of the inducer to system surge components are described in detail. Finally a description of a simple lumped-parameter hydraulic system model developed to better understand observed data is given.

Cavitation instabilities in hydraulic machines

International Nuclear Information System (INIS)

Tsujimoto, Y

2013-01-01

Cavitation instabilities in hydraulic machines, hydro turbines and turbopump inducers, are reviewed focusing on the cause of instabilities. One-dimensional model of hydro turbine system shows that the overload surge is caused by the diffuser effect of the draft tube. Experiments show that this effect also causes the surge mode oscillations at part load. One dimensional model of a cavitating turbopump inducer shows that the mass flow gain factor, representing the cavity volume increase caused by the incidence angle increase is the cause of cavitation surge and rotating cavitation. Two dimensional model of a cavitating turbopump inducer shows that various modes of cavitation instabilities start to occur when the cavity length becomes about 65% of the blade spacing. This is caused by the interaction of the local flow near the cavity trailing edge with the leading edge of the next blade. It was shown by a 3D CFD that this is true also for real cases with tip cavitation. In all cases, it was shown that cavitation instabilities are caused by the fundamental characteristics of cavities that the cavity volume increases with the decrease of ambient pressure or the increase of the incidence angle

7 CFR 58.228 - Dump hoppers, screens, mixers and conveyors.

Science.gov (United States)

2010-01-01

... Service 1 Equipment and Utensils § 58.228 Dump hoppers, screens, mixers and conveyors. The product contact surfaces of dump hoppers, screens, mixers and conveyors which are used in the process of transferring dry... 7 Agriculture 3 2010-01-01 2010-01-01 false Dump hoppers, screens, mixers and conveyors. 58.228...

Problems of bentonite rebonding of synthetic system sands in turbine mixers

Directory of Open Access Journals (Sweden)

A. Fedoryszyn

2008-12-01

Full Text Available Turbine (rotor mixers are widely used in foundries for bentonite rebonding of synthetic system sands. They form basic equipment in modern sand processing plants. Their major advantage is the short time of the rebond mixing cycle.Until now, no complete theoretical description of the process of mixing in turbine mixers has been offered. Neither does it seem reasonable to try to adapt the theoretical backgrounds of the mixing process carried out in mixers of other types, for example, rooler mixers [1], to the description of operation of the turbine mixers. Truly one can risk the statement that the individual fundamental operations of mixing in rooler mixers, like kneading, grinding, mixing and thinning, are also performed in turbine mixers. Yet, even if so, in turbine mixers these processes are proceeding at a rate and intensity different than in the roller mixers. The fact should also be recalled that the theoretical backgrounds usually relate to the preparation of sand mixtures from new components, and this considerably restricts the field of application of these descriptions when referred to rebond mixing of the system sand. The fundamentals of the process of the synthetic sand rebonding with bentonite require determination and description of operations, like disaggregation, even distribution of binder and water within the entire volume of the rebonded sand batch, sand grains coating, binder activation and aeration.This study presents the scope of research on the sand rebonding process carried out in turbine mixers. The aim has been to determine the range and specific values of the designing and operating parameters to get optimum properties of the rebonded sand as well as energy input in the process.

Hybrid reactor based on combined cavitation and ozonation: from concept to practical reality.

Science.gov (United States)

Gogate, P R; Mededovic-Thagard, S; McGuire, D; Chapas, G; Blackmon, J; Cathey, R

2014-03-01

The present work gives an in depth discussion related to the development of a hybrid advanced oxidation reactor, which can be effectively used for the treatment of various types of water. The reactor is based on the principle of intensifying degradation/disinfection using a combination of hydrodynamic cavitation, acoustic cavitation, ozone injection and electrochemical oxidation/precipitation. Theoretical studies have been presented to highlight the uniform distribution of the cavitational activity and enhanced generation of hydroxyl radicals in the cavitation zone, as well as higher turbulence in the main reactor zone. The combination of these different oxidation technologies have been shown to result in enhanced water treatment ability, which can be attributed to the enhanced generation of hydroxyl radicals, enhanced contact of ozone and contaminants, and the elimination of mass transfer resistances during electrochemical oxidation/precipitation. Compared to the use of individual approaches, the hybrid reactor is expected to intensify the treatment process by 5-20 times, depending on the application in question, which can be confirmed based on the literature illustrations. Also, the use of Ozonix® has been successfully proven while processing recycled fluids at commercial sites on over 750 oil and natural gas wells during hydraulic operations around the United States. The superiority of the hybrid process over conventional chemical treatments in terms of bacteria and scale reduction as well as increased water flowability and better chemical compatibility, which is a key requirement for oil and gas applications, has been established. Copyright © 2013 Elsevier B.V. All rights reserved.

Granular flow in static mixers by coupled DEM/CFD approach

Directory of Open Access Journals (Sweden)

Pezo Lato

2016-01-01

Full Text Available The mixing process greatly influence the mixing efficiency, as well as the quality and the price of the intermediate and/or the final product. Static mixer is used for premixing action before the main mixing process, for significant reduction of mixing time and energy consumption. This type of premixing action is not investigated in detail in the open literature. In this article, the novel numerical approach called Discrete Element Method is used for modelling of granular flow in multiple static mixer applications (1 - 3 Komax or Ross mixing elements were utilized, while the Computational Fluid Dynamic method was chosen for fluid flow modelling, using the Eulerian multiphase model. The main aim of this article is to predict the behaviour of granules being gravitationally transported in different mixer configuration and to choose the best configuration of the mixer taking into account the total particle path, the number of mixing elements and the quality of the obtained mixture. The results of the numerical simulations in the static mixers were compared to experimental results, the mixing quality is examined by RSD (relative standard deviation criterion, and the effects on the mixer type and the number of mixing elements on mixing process were studied. The effects of the mixer type and the number of mixing elements on mixing process were studied using analysis of variance (ANOVA. Mathematical modelling is used for optimization of number of Ross and Komax segments in mixer in order to gain desirable mixing results. [Projekat Ministarstva nauke Republike Srbije, br. TR31055

Cavitation noise studies on marine propellers

Science.gov (United States)

Sharma, S. D.; Mani, K.; Arakeri, V. H.

1990-04-01

Experimental observations are described of cavitation inception and noise from five model propellers, three basic and two modified, tested in the open jet section of the Indian Institute of Science high-speed water tunnel facility. Extensive experiments on the three basic propellers of different design, which included visualization of cavitation and measurements of noise, showed that the dominant type of cavitation was in the form of tip vortex cavitation, accompanied by leading edge suction side sheet cavitation in its close vicinity, and the resultant noise depended on parameters such as the advance coefficient, the cavitation number, and the propeller geometry. Of these, advance coefficient was found to have the maximum influence not only on cavitation noise but also on the inception of cavitation. Noise levels and frequencies of spectra obtained from all the three basic propellers at conditions near inception and different advance coefficient values, when plotted in the normalized form as suggested by Blake, resulted in a universal spectrum which would be useful for predicting cavitation noise at prototype scales when a limited extent of cavitation is expected in the same form as observed on the present models. In an attempt to delay the onset of tip vortex cavitation, the blades of two of the three basic propellers were modified by drilling small holes in the tip and leading edge areas. Studies on the modified propellers showed that the effectiveness of the blade modification was apparently stronger at low advance coefficient values and depended on the blade sectional profile. Measurements of cavitation noise indicated that the modification also improved the acoustic performance of the propellers as it resulted in a complete attenuation of the low-frequency spectral peaks, which were prominent with the basic propellers. In addition to the above studies, which were conducted under uniform flow conditions, one of the basic propellers was tested in the simulated

Research on Mixer Parametric Modeling System Based on Redevelopment of ANSYS

Directory of Open Access Journals (Sweden)

Bin Zheng

2015-01-01

Full Text Available In this paper, the mixer parametric modeling system software was developed by using VB which was taken as the foreground development program, and the paper combined with ANSYS software to create the finite element model of mixer blade and cylinder for the following numerical simulation of the flow field and parameter optimization of mixer. The software user interface was developed by VB and the pre-process model was created by invoking APDL of ANSYS in background. Therefore, the operation of modeling, meshing, component-building of mixer blade and cylinder were completed by using APDL and the graphic and text were outputted and displayed on the mixer parametric modeling system user interface which was developed by VB. Practice proved that it is convenient to modify the mixer solid model created by the parametric design language of ANSYS due to the similar structure.

Mixer pump test plan for double shell tank AZ-101

International Nuclear Information System (INIS)

STAEHR, T.W.

1999-01-01

Mixer pump systems have been chosen as the method for retrieval of tank wastes contained in double shell tanks at Hanford. This document describes the plan for testing and demonstrating the ability of two 300 hp mixer pumps to mobilize waste in tank AZ-101. The mixer pumps, equipment and instrumentation to monitor the test were installed by Project W-151

Cavitation and non-cavitation regime for large-scale ultrasonic standing wave particle separation systems--In situ gentle cavitation threshold determination and free radical related oxidation.

Science.gov (United States)

Johansson, Linda; Singh, Tanoj; Leong, Thomas; Mawson, Raymond; McArthur, Sally; Manasseh, Richard; Juliano, Pablo

2016-01-01

We here suggest a novel and straightforward approach for liter-scale ultrasound particle manipulation standing wave systems to guide system design in terms of frequency and acoustic power for operating in either cavitation or non-cavitation regimes for ultrasound standing wave systems, using the sonochemiluminescent chemical luminol. We show that this method offers a simple way of in situ determination of the cavitation threshold for selected separation vessel geometry. Since the pressure field is system specific the cavitation threshold is system specific (for the threshold parameter range). In this study we discuss cavitation effects and also measure one implication of cavitation for the application of milk fat separation, the degree of milk fat lipid oxidation by headspace volatile measurements. For the evaluated vessel, 2 MHz as opposed to 1 MHz operation enabled operation in non-cavitation or low cavitation conditions as measured by the luminol intensity threshold method. In all cases the lipid oxidation derived volatiles were below the human sensory detection level. Ultrasound treatment did not significantly influence the oxidative changes in milk for either 1 MHz (dose of 46 kJ/L and 464 kJ/L) or 2 MHz (dose of 37 kJ/L and 373 kJ/L) operation. Copyright © 2015 Elsevier B.V. All rights reserved.

Mixer-settler performance evaluation in actinide extraction

International Nuclear Information System (INIS)

Camilo, R.L.; Goncalves, M.A.; Carvalho, E.I.; Nakazone, A.K.; Araujo, B.F. de; Araujo, J.A.

1988-07-01

This paper deals with four conceptions of mixer-settlers used for actinide purification and recovery. By means of the uranium concentration profiles in the organic and aqueous phases, the evaluation of each mixer-settler was made. The main purpose of this work is the data acquisition, for adapting the different contactor types to actinide recovery by liquid-liquid extraction, in the nuclear fuel cycle. (autor) [pt

Fundamentals of Cavitation

CERN Document Server

Franc, Jean-Pierre

2005-01-01

The present book is aimed at providing a comprehensive presentation of cavitation phenomena in liquid flows. It is further backed up by the experience, both experimental and theoretical, of the authors whose expertise has been internationally recognized. A special effort is made to place the various methods of investigation in strong relation with the fundamental physics of cavitation, enabling the reader to treat specific problems independently. Furthermore, it is hoped that a better knowledge of the cavitation phenomenon will allow engineers to create systems using it positively. Examples in the literature show the feasibility of this approach.

A novel ultrasonic cavitation enhancer

NARCIS (Netherlands)

Rivas, Fernandez D.; Verhaagen, B.; Galdamez Perez, Andres; Castro-Hernandez, Elena; Zwieten, Van Ralph; Schroen, Karin

2015-01-01

We introduce a Cavitation Intensifying Bag as a versatile tool for acoustic cavitation control. The cavitation activity is spatially controlled by the modification of the inner surface of the bag with patterned pits of microscopic dimensions. We report on different measurements such as the

A novel ultrasonic cavitation enhancer

NARCIS (Netherlands)

Fernandez Rivas, David; Verhaagen, B.; Galdamez Perez, Andres; Castro-Hernandez, Elena; van Zwieten, Ralph; Schroen, Karin

2015-01-01

We introduce a Cavitation Intensifying Bag as a versatile tool for acoustic cavitation control. The cavitation activity is spatially controlled by the modification of the inner surface of the bag with patterned pits of microscopic dimensions. We report on different measurements such as the

Hot-electron bolometer terahertz mixers for the Herschel Space Observatory.

Science.gov (United States)

Cherednichenko, Sergey; Drakinskiy, Vladimir; Berg, Therese; Khosropanah, Pourya; Kollberg, Erik

2008-03-01

We report on low noise terahertz mixers (1.4-1.9 THz) developed for the heterodyne spectrometer onboard the Herschel Space Observatory. The mixers employ double slot antenna integrated superconducting hot-electron bolometers (HEBs) made of thin NbN films. The mixer performance was characterized in terms of detection sensitivity across the entire rf band by using a Fourier transform spectrometer (from 0.5 to 2.5 THz, with 30 GHz resolution) and also by measuring the mixer noise temperature at a limited number of discrete frequencies. The lowest mixer noise temperature recorded was 750 K [double sideband (DSB)] at 1.6 THz and 950 K DSB at 1.9 THz local oscillator (LO) frequencies. Averaged across the intermediate frequency band of 2.4-4.8 GHz, the mixer noise temperature was 1100 K DSB at 1.6 THz and 1450 K DSB at 1.9 THz LO frequencies. The HEB heterodyne receiver stability has been analyzed and compared to the HEB stability in the direct detection mode. The optimal local oscillator power was determined and found to be in a 200-500 nW range.

The development of terahertz superconducting hot-electron bolometric mixers

International Nuclear Information System (INIS)

Semenov, Alexei; Richter, Heiko; Smirnov, Konstantin; Voronov, Boris; Gol'tsman, Gregory; Huebers, Heinz-Wilhelm

2004-01-01

We present recent advances in the development of NbN hot-electron bolometric (HEB) mixers for flying terahertz heterodyne receivers. Three important issues have been addressed: the quality of the source NbN films, the effect of the bolometer size on the spectral properties of different planar feed antennas, and the local oscillator (LO) power required for optimal operation of the mixer. Studies of the NbN films with an atomic force microscope indicated a surface structure that may affect the performance of the smallest mixers. Measured spectral gain and noise temperature suggest that at frequencies above 2.5 THz the spiral feed provides better overall performance than the double-slot feed. Direct measurements of the optimal LO power support earlier estimates made in the framework of the uniform mixer model

Simulation of time variation of Uranium, Plutonium and fission product hold up in mixer settler contactors

International Nuclear Information System (INIS)

Dionisi, M.; D'Agostino, F.; Remetti, R.

1990-01-01

A simulation model of PUREX process extraction phase for a contactors (mixer-settlers) battery has been developed. This model has been implemented in a FORTRAN code tailored both for mainframe and PC. The main goal of the code is to determine Uranium and Plutonium hold-ups vs.time within contactors in order to implement a NRTA project for a reprocessing plant. These results are extremely important for a complete analysis of NRTA system perfomance particularly to overcome the difficulty of executing physical inventory within liquid-liquid contactors of extraction lines. The chemical process simulation has been carried out conventional theoretical models with the exeption of hydrodynamic simulation which has been developed utilizing a model based on experimental results

Methodology for calculating power consumption of planetary mixers

Science.gov (United States)

Antsiferov, S. I.; Voronov, V. P.; Evtushenko, E. I.; Yakovlev, E. A.

2018-03-01

The paper presents the methodology and equations for calculating the power consumption necessary to overcome the resistance of a dry mixture caused by the movement of cylindrical rods in the body of a planetary mixer, as well as the calculation of the power consumed by idling mixers of this type. The equations take into account the size and physico-mechanical properties of mixing material, the size and shape of the mixer's working elements and the kinematics of its movement. The dependence of the power consumption on the angle of rotation in the plane perpendicular to the axis of rotation of the working member is presented.

Cavitation erosion in sodium flow, sodium cavitation tunnel testing

International Nuclear Information System (INIS)

Courbiere, Pierre.

1981-04-01

The high-volume sodium flows present in fast neutron reactors are liable to induce cavitation phenomena in various portion of the sodium lines and pumps. The absence of sufficient data in this area led the C.E.A. to undertake an erosion research program in cavitating sodium flow. This paper discusses the considerations leading to the definition and execution of sodium cavitation erosion tests, and reviews the tests run with 400 0 C sodium on various steel grades: 316, 316 L, 316 Ti (Z8CNDT17-12), Poral (Z3CND18-12), 304 L and LN2 - clad 316 L (Ni coating-clad 316 L). Acoustic detection and signal processing methods were used with an instrument package designed and implemented at the Cadarache Nuclear Research Center

Alternate paddle configuration for improved wear resistance in the saltstone mixer

Energy Technology Data Exchange (ETDEWEB)

Reigel, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Fowley, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2013-09-23

The Saltstone Production Facility has a 10-inch Readco-Kurimoto continuous mixer that mixes the premix dry feeds and low-level waste salt solution to make fresh (uncured) saltstone. Inspection of the mixer in January 2013 showed significant wear on the third, fourth and fifth paddle pairs after the conveying augers. A 2-inch Readco-Kurimoto continuous mixer was used to test alternate paddle configurations for use in the 10-inch mixer to decrease the wear rate on the paddles. Two wear tests were conducted to investigate a method of reducing wear on the mixer paddles. The first test (wear test 2a) had a paddle configuration similar to the currently installed 10-inch mixer in the SPF. This test established baseline wear. The second test (wear test 2b) had a reconfigured paddle arrangement that replaced the flat paddles with helical paddles for paddle pairs 2 - 6 and aligned paddle pair 1 with the augers. The intent of the reconfiguration was to more effectively convey the partially wetted dry feeds through the transition region and into the liquid feed where paddle wear is reduced due to dry feeds and salt solution being mixed at the intended water to premix ratio. The design of the helical paddles provides conveyance through the transition region to the liquid feed inlet. The alignment with the auger is aimed to provide a smoother transition (minimizing the discontinuity between the auger and paddle pair 1) into the downstream paddles. A soft metal with low wear resistance (6000 series aluminum) was used for the wear testing paddles to determine wear patterns while minimizing run time and maximizing wear rate. For the two paddle configurations tested using the scaled 2-inch Readco-Kurimoto continuous mixer, with the first six paddles after the augers replaced by the wear paddles and the remaining paddles were stainless steel. Since the 10-inch SPF mixer is designed with the liquid inlet centered over paddle pairs 5 and 6, the scaled 2-inch mixer was configured the

Numerical simulation and PEPT measurements of a 3D conical helical-blade mixer: a high potential solids mixer for solid-state fermentation

NARCIS (Netherlands)

Schutyser, M.A.I.; Briels, W.J.; Rinzema, A.; Boom, R.M.

2003-01-01

Helical-blade solids mixers have a large potential as bioreactors for solid-state fermentation (SSF). Fundamental knowledge of the flow and mixing behavior is required for robust operation of these mixers. In this study predictions of a discrete particle model were compared to experiments with

Planar Submillimeter-Wave Mixer Technology with Integrated Antenna

Science.gov (United States)

Chattopadhyay, Gautam; Mehdi, Imran; Gill, John J.; Lee, Choonsup; lombart, Muria L.; Thomas, Betrand

2010-01-01

High-performance mixers at terahertz frequencies require good matching between the coupling circuits such as antennas and local oscillators and the diode embedding impedance. With the availability of amplifiers at submillimeter wavelengths and the need to have multi-pixel imagers and cameras, planar mixer architecture is required to have an integrated system. An integrated mixer with planar antenna provides a compact and optimized design at terahertz frequencies. Moreover, it leads to a planar architecture that enables efficient interconnect with submillimeter-wave amplifiers. In this architecture, a planar slot antenna is designed on a thin gallium arsenide (GaAs) membrane in such a way that the beam on either side of the membrane is symmetric and has good beam profile with high coupling efficiency. A coplanar waveguide (CPW) coupled Schottky diode mixer is designed and integrated with the antenna. In this architecture, the local oscillator (LO) is coupled through one side of the antenna and the RF from the other side, without requiring any beam sp litters or diplexers. The intermediate frequency (IF) comes out on a 50-ohm CPW line at the edge of the mixer chip, which can be wire-bonded to external circuits. This unique terahertz mixer has an integrated single planar antenna for coupling both the radio frequency (RF) input and LO injection without any diplexer or beamsplitters. The design utilizes novel planar slot antenna architecture on a 3- mthick GaAs membrane. This work is required to enable future multi-pixel terahertz receivers for astrophysics missions, and lightweight and compact receivers for planetary missions to the outer planets in our solar system. Also, this technology can be used in tera hertz radar imaging applications as well as for testing of quantum cascade lasers (QCLs).

Quantum limited quasiparticle mixers at 100 GHz

International Nuclear Information System (INIS)

Mears, C.A; Hu, Qing; Richards, P.L.; Worsham, A.H.; Prober, D.E.; Raeisaenen, A.V.

1990-09-01

We have made accurate measurements of the noise and gain of superconducting-insulating-superconducting (SIS) mixers employing small area (1μm 2 ) Ta/Ta 2 O 5 /Pb 0.9 Bi 0.1 tunnel junctions. We have measured an added mixer noise of 0.61 +/- 0.31 quanta at 95.0 GHz, which is within 25 percent of the quantum limit of 0.5 quanta. We have carried out a detailed comparison between theoretical predictions of the quantum theory of mixing and experimentally measured noise and gain. We used the shapes of I-V curves pumped at the upper and lower sideband frequencies to deduce values of the embedding admittances at these frequencies. Using these admittances, the mixer noise and gain predicted by quantum theory are in excellent agreement with experiment. 21 refs., 9 figs

Cavitation problems in sodium valves

International Nuclear Information System (INIS)

Elie, X.

1976-01-01

Cavitation poses few problems for sodium valves, in spite of the fact that the loops are not pressurized. This is no doubt due to the low flow velocities in the pipes. For auxiliary loop valves we are attempting to standardize performances with respect to cavitation. For economic reasons cavitation thresholds are approached with large diameter valves. (author)

Numerical and experimental investigations on cavitation erosion

Science.gov (United States)

Fortes Patella, R.; Archer, A.; Flageul, C.

2012-11-01

A method is proposed to predict cavitation damage from cavitating flow simulations. For this purpose, a numerical process coupling cavitating flow simulations and erosion models was developed and applied to a two-dimensional (2D) hydrofoil tested at TUD (Darmstadt University of Technology, Germany) [1] and to a NACA 65012 tested at LMH-EPFL (Lausanne Polytechnic School) [2]. Cavitation erosion tests (pitting tests) were carried out and a 3D laser profilometry was used to analyze surfaces damaged by cavitation [3]. The method allows evaluating the pit characteristics, and mainly the volume damage rates. The paper describes the developed erosion model, the technique of cavitation damage measurement and presents some comparisons between experimental results and numerical damage predictions. The extent of cavitation erosion was correctly estimated in both hydrofoil geometries. The simulated qualitative influence of flow velocity, sigma value and gas content on cavitation damage agreed well with experimental observations.

Far-ir heterodyne radiometric measurements with quasioptical Schottky diode mixers

International Nuclear Information System (INIS)

Fetterman, H.R.; Tannenwald, P.E.; Clifton, B.J.; Parker, C.D.; Fitzgerald, W.D.; Erickson, N.R.

1978-01-01

We have made heterodyne radiometric measurements with GaAs Schottky diode mixers, mounted in a corner-reflector configuration, over the spectral range 170 μm to 1 mm. At 400 μm, system noise temperatures of 9700 K DSB (NEP=1.4 x 10 - 19 W/Hz) and mixer noise temperatures of 5900 K have been achieved. This same quasioptical mixer has also been used to generate 10 - 7 W of tunable radiation suitable for spectroscopic applications

Turbulent measurements in the lobe mixer of a turbofan engine. Turbofan engine lobe mixer nagare no ranryu keisoku

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Makoto; Ogawa, Yuji; Arakawa, Chuichi; Tagori, Tetsuo [Ishikawajima-Harima Heavy Industries, Co., Ltd., Tokyo, (Japan) Nippon Steel Corp., Tokyo, (Japan) The Univ. of Tokyo, Tokyo, (Japan). Faculty of Engineering The Univ. of Tsukuba, Tsukuba, (Japan)

1990-01-25

In order to examine the flow generated by the lobe mixer of a turbofan engine precisely, after measuring a three dimensional turbulent flow by a hot-wire anemometer, the mixing process of a bypass flow and a core flow with cross-sectional vortexes, and factors generating the vortex were clarified experimentally using the scale model of an exhaust duct with the lobe mixer. As a result, the mixing process was strongly affected by a lobe tip figure and a lobe figure near a center-body, and affected by the minimum gap between the lobe and center-body. The subsequent mixing process was scarcely affected by the ratio of a core flow velocity to a bypass flow one, although strongly affected by flow conditions on a lobe surface. Since the lobe mixer promoted the mixing around a center axis shifting a fast core flow outwards, it was unfavorable to mixing, however, it was expected to be useful for reducing engine jet noise. 3 refs., 7 figs.

Appearance of high submerged cavitating jet: The cavitation phenomenon and sono luminescence

Directory of Open Access Journals (Sweden)

Hutli Ezddin

2013-01-01

Full Text Available In order to study jet structure and behaviour of cloud cavitation within time and space, visualization of highly submerged cavitating water jet has been done using Stanford Optics 4 Quick 05 equipment, through endoscopes and other lenses with Drello3244 and Strobex Flash Chadwick as flashlight stroboscope. This included obligatory synchronization with several types of techniques and lenses. Images of the flow regime have been taken, allowing calculation of the non-dimensional cavitation cloud length under working conditions. Consequently a certain correlation has been proposed. The influencing parameters, such as; injection pressure, downstream pressure and cavitation number were experimentally proved to be very significant. The recordings of sono-luminescence phenomenon proved the collapsing of bubbles everywhere along the jet trajectory. In addition, the effect of temperature on sono-luminescence recordings was also a point of investigation. [Projekat Ministarstva nauke Republike Srbije, br. TR35046

Cavitation nucleation in gelatin: Experiment and mechanism.

Science.gov (United States)

Kang, Wonmo; Adnan, Ashfaq; O'Shaughnessy, Thomas; Bagchi, Amit

2018-02-01

Dynamic cavitation in soft materials is becoming increasingly relevant due to emerging medical implications such as the potential of cavitation-induced brain injury or cavitation created by therapeutic medical devices. However, the current understanding of dynamic cavitation in soft materials is still very limited, mainly due to lack of robust experimental techniques. To experimentally characterize cavitation nucleation under dynamic loading, we utilize a recently developed experimental instrument, the integrated drop tower system. This technique allows quantitative measurements of the critical acceleration (a cr ) that corresponds to cavitation nucleation while concurrently visualizing time evolution of cavitation. Our experimental results reveal that a cr increases with increasing concentration of gelatin in pure water. Interestingly, we have observed the distinctive transition from a sharp increase (pure water to 1% gelatin) to a much slower rate of increase (∼10× slower) between 1% and 7.5% gelatin. Theoretical cavitation criterion predicts the general trend of increasing a cr , but fails to explain the transition rates. As a likely mechanism, we consider concentration-dependent material properties and non-spherical cavitation nucleation sites, represented by pre-existing bubbles in gels, due to possible interplay between gelatin molecules and nucleation sites. This analysis shows that cavitation nucleation is very sensitive to the initial configuration of a bubble, i.e., a non-spherical bubble can significantly increase a cr . This conclusion matches well with the experimentally observed liquid-to-gel transition in the critical acceleration for cavitation nucleation. From a medical standpoint, understanding dynamic cavitation within soft materials, i.e., tissues, is important as there are both potential injury implications (blast-induced cavitation within the brain) as well as treatments utilizing the phenomena (lithotripsy). In this regard, the main

Numerical simulation of cryogenic cavitating flow by an extended transport-based cavitation model with thermal effects

Science.gov (United States)

Zhang, Shaofeng; Li, Xiaojun; Zhu, Zuchao

2018-06-01

Thermodynamic effects on cryogenic cavitating flow is important to the accuracy of numerical simulations mainly because cryogenic fluids are thermo-sensitive, and the vapour saturation pressure is strongly dependent on the local temperature. The present study analyses the thermal cavitating flows in liquid nitrogen around a 2D hydrofoil. Thermal effects were considered using the RNG k-ε turbulence model with a modified turbulent eddy viscosity and the mass transfer homogenous cavitation model coupled with energy equation. In the cavitation model process, the saturated vapour pressure is modified based on the Clausius-Clapron equation. The convection heat transfer approach is also considered to extend the Zwart-Gerber-Belamri model. The predicted pressure and temperature inside the cavity under cryogenic conditions show that the modified Zwart-Gerber-Belamri model is in agreement with the experimental data of Hord et al. in NASA, especially in the thermal field. The thermal effect significantly affects the cavitation dynamics during phase-change process, which could delay or suppress the occurrence and development of cavitation behaviour. Based on the modified Zwart-Gerber-Belamri model proposed in this paper, better prediction of the cryogenic cavitation is attainable.

Numerical simulation and PEPT measurements of a 3D conical helical-bla de mixer: A high potential solids mixer for solid-state fermentation

NARCIS (Netherlands)

Schutyser, M.A.I.; Schutyser, M.A.I.; Briels, Willem J.; Rinzema, A.; Boom, R.M.; Boom, R.M.

2003-01-01

Helical-blade solids mixers have a large potential as bioreactors for solid-state fermentation (SSF). Fundamental knowledge of the flow and mixing behavior is required for robust operation of these mixers. In this study predictions of a discrete particle model were compared to experiments with

Experimental research of a microjet cavitation

Directory of Open Access Journals (Sweden)

Olšiak Róbert

2012-04-01

Full Text Available The paper presents some results of a cavitation research behind a micro-orifice. Investigated were the conditions of the origin of cavitation represented by parameters such as upstream pressure, downstream pressure, liquid temperature and cavitation number. Presented are also images of a cavitating microjet made by the high speed high definition camera RedLake Y3. Dimensions of a microjet are: diameter 0,3 mm; length 0,5 mm.

An Investigation into the Effect of Hydrodynamic Cavitation on Diesel using Optical Extinction

Science.gov (United States)

Lockett, R. D.; Fatmi, Z.; Kuti, O.; Price, R.

2015-12-01

A conventional diesel and paraffinic-rich model diesel fuel were subjected to sustained cavitation in a custom-built high-pressure recirculation flow rig. Changes to the spectral extinction coefficient at 405 nm were measured using a simple optical arrangement. The spectral extinction coefficient at 405 nm for the conventional diesel sample was observed to increase to a maximum value and then asymptotically decrease to a steady-state value, while that for the paraffinic-rich model diesel was observed to progressively decrease. It is suggested that this is caused by the sonochemical pyrolysis of mono-aromatics to form primary soot-like carbonaceous particles, which then coagulate to form larger particles, which are then trapped by the filter, leading to a steady-state spectral absorbance.

Flow regimes in a T-mixer operating with a binary mixture

Science.gov (United States)

Camarri, Simone; Siconolfi, Lorenzo; Galletti, Chiara; Salvetti, Maria Vittoria

2015-11-01

Efficient mixing in small volumes is a key target in many processes. Among the most common micro-devices, passive T-shaped micro-mixers are widely used. For this reason, T-mixers have been studied in the literature and its working flow regimes have been identified. However, in most of the available theoretical studies it is assumed that only one working fluid is used, i.e. that the same fluid at the same thermodynamic conditions is entering the two inlet conduits of the mixer. Conversely, the practical use of micro-devices often involves the mixing of two different fluids or of the same fluid at different thermodynamic conditions. In this case flow regimes significantly different than those observed for a single working fluid may occur. The present work aims at investigating the flow regimes in a T-mixers when water at two different temperatures, i.e. having different viscosity and density, is entering the mixer. The effect of the temperature difference on the flow regimes in a 3D T-mixer is investigated by DNS and stability analysis and the results are compared to the case in which a single working fluid is employed.

Quasi-optical antenna-mixer-array design for terahertz frequencies

Science.gov (United States)

Guo, Yong; Potter, Kent A.; Rutledge, David B.

1992-01-01

A new quasi-optical antenna-mixer-array design for terahertz frequencies is presented. In the design, antenna and mixer are combined into an entity, based on the technology in which millimeter-wave horn antenna arrays have been fabricated in silicon wafers. It consists of a set of forward- and backward-looking horns made with a set of silicon wafers. The front side is used to receive incoming signal, and the back side is used to feed local oscillator signal. Intermediate frequency is led out from the side of the array. Signal received by the horn array is picked up by antenna probes suspended on thin silicon-oxynitride membranes inside the horns. Mixer diodes will be located on the membranes inside the horns. Modeling of such an antenna-mixer-array design is done on a scaled model at microwave frequencies. The impedance matching, RF and LO isolation, and patterns of the array have been tested and analyzed.

Transitory powder flow dynamics during emptying of a continuous mixer

OpenAIRE

Ammarcha , Chawki; Gatumel , Cendrine; Dirion , Jean-Louis; Cabassud , Michel; Mizonov , Vadim; Berthiaux , Henri

2013-01-01

International audience; This article investigates the emptying process of a continuous powder mixer, from both experimental and modelling points of view. The apparatus used in this work is a pilot scale commercial mixer Gericke GCM500, for which a specific experimental protocol has been developed to determine the hold up in the mixer and the real outflow. We demonstrate that the dynamics of the process is governed by the rotational speed of the stirrer, as it fixes characteristic values of th...

Influence of superoleophobic layer on the lubrication performance of partially textured bearing including cavitation

Science.gov (United States)

Tauviqirrahman, M.; Bayuseno, A. P.; Muchammad, Jamari, J.

2016-04-01

Surfaces with high superoleophobicity have attracted important attention because of their potential applications in scientific and industrial field. Especially classical metal bearing are faced with lubrication problem, because metal surface shows typically oleophilicity. The development of superolephobic metal surfaces which repel oil liquid droplet have significant applications in preventing the stiction. In addition, for classical bearing with texturing, the cavitation occurence is often considered as the main cause of the deterioration of the lubrication performance and thus shorten the lifetime of the bearing. In the present study, the exploration of the influence of adding the superoleophobic layer on the improvement of the performance of partially textured bearing in preventing the cavitation was performed. Navier slip model was used to model the behavior of the superoleophobic layer. A formulation of the modified Reynolds equation with mass-conserving boundary conditions was derived and the pressure distribution was of particular interest. The equations of lubrication were discretized using a finite volume method and solved using a tri-diagonal-matrix-algortihm. In this calculation, it was shown that after introducing the superoleophobic layer at the leading edge of the contact, the cavitation occurence can be prevented and thus the increased hydrodynamic pressure is found. However, the results showed that for deeper texture, the deterioration of the load support is noted. This findings may have useful implications to extend the life time of textured bearing.

Development of air pulsed ejector mixer settlers of different capacities

Energy Technology Data Exchange (ETDEWEB)

Rajagopalan, C V; Periasamy, K; Koganti, S B [Reprocessing Programme, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

1994-06-01

Nuclear industry has made significant contributions in the development of liquid-liquid contactors, for the separation of one or more solutes from feed solutions wherein they provide a more economical alternative compared to other unit operations. The various equipment that are used can be broadly classified into three categories: (1) mixer settlers (2) liquid pulsed sieve plate columns (3) centrifugal contactors. Each one has its own merits and demerits. Mixer settlers score over the other contactors in their simple design and reliable operation over a wide range of process conditions. Air pulsed mixer settlers of different designs are in use in the fuel reprocessing industry. The present paper describes the development of a new type of mixer settler based on ejector as the mixing device. (author). 7 refs., 3 figs., 1 tab.

A Matlab-Based Graphical User Interface for Simulation and Control Design of a Hydrogen Mixer

Science.gov (United States)

Richter, Hanz; Figueroa, Fernando

2003-01-01

A Graphical User Interface (GUI) that facilitates prediction and control design tasks for a propellant mixer is described. The Hydrogen mixer is used in rocket test stand operations at the NASA John C. Stennis Space Center. The mixer injects gaseous hydrogen (GH2) into a stream of liquid hydrogen (LH2) to obtain a combined flow with desired thermodynamic properties. The flows of GH2 and LH2 into the mixer are regulated by two control valves, and a third control valve is installed at the exit of the mixer to regulate the combined flow. The three valves may be simultaneously operated in order to achieve any desired combination of total flow, exit temperature and mixer pressure within the range of operation. The mixer, thus, constitutes a three-input, three-output system. A mathematical model of the mixer has been obtained and validated with experimental data. The GUI presented here uses the model to predict mixer response under diverse conditions.

Improvement of residual stress in stainless steel by cavitating jet; Cavitation funryu ni yoru stainless ko no zanryu oryoku kaizen

Energy Technology Data Exchange (ETDEWEB)

Soyama, H.; Saka, M. [Tohoku Univ., Sendai (Japan)] Park, J. [Kyung Nam Junior College, Pusan (Korea, Republic of). Dept. Vehicle Eng.] Abe, H. [Tohoku Univ., Sendai (Japan)

1998-08-15

In order to strengthen materials, the improvement of residual stress in stainless steel by using a cavitating jet was investigated. In case of cavitating jet, the cavitation intensity can be controlled by hydraulic parameters such as upstream pressure and downstream pressure. In general, cavitation produces damage on hydraulic machinery. However, at the initial stage of cavitation erosion process, plastic deformation takes place on the material surface, then it is possible to do peening without damage considering the cavitation intensity and the exposure time. In order to evidence the suitable condition on the improvement of residual stress by the cavitating jet, the residual stress in SUS304 and SUS316 was examined. The three normal stresses in different directions were measured by X-ray diffraction method, then the principal stresses were calculated. Both principal stresses were changed from tension to compression within 10 seconds by the cavitating jet. The compressive stress resulted by the cavitating jet was saturated after a certain time. It was concluded that the cavitating jet improved the residual stress in stainless steel SUS316 as well as SUS304. 24 refs., 9 figs.

Disintegration of materials by cavitating microjets

Directory of Open Access Journals (Sweden)

Mlkvik M.

2013-04-01

Full Text Available In the paper is presented an investigation of material disintegration by cavitating microjets. Cavitating microjet develops behind the micro-orifice at high flow speeds, when local pressure drop initiates a cavitation phenomenon. Described is a method and presented are selected results of experiments. Experiments were carried out with 2 micro-orifices at different flow conditions (cavitation number, distance between sample and micro-orifice. Experiments are based on flow visualisation as well as on a character of material displacement.

Fracture of elastomers by cavitation

KAUST Repository

Hamdi, Adel

2014-01-01

Cavitation phenomenon is studied in rubber-like materials by combining experimental, theoretical and numerical approaches. Specific tests are carried out on a Styrene Butadiene Rubber to point out main characteristics of cavitation phenomenon. Hydrostatic depression is numerically modelled using finite element method. Numerical results are compared to Ball\\'s and Hou & Abeyaratne\\'s models with regard to cavity nucleation in the material. Both models well fit experimental observations suggesting that the cavitation nucleation in elastomers depends on the confinement degree of the specimen. Finally, critical hydrostatic pressure and critical global deformation are proved to govern cavitation nucleation in the studied material. Critical loadings are identified by comparing experimental and numerical load-displacement curves. © 2013 Elsevier Ltd.

Experimental and numerical investigations on spray structure under the effect of cavitation phenomenon in a microchannel

International Nuclear Information System (INIS)

Ghorbani, Morteza; Sadaghiani, Abdolali Khalili; Yidiz, Mehmet; Kosar, Ali

2017-01-01

In this study, the effect of upstream pressure on cavitation flows inside a microchannel with an inner diameter of 152 μm and resulting spray structure were experimentally and numerically investigated. The effects of bubble number density on two-phase flow hydrodynamics were studied using the numerical approach, where transient model was utilized to obtain the changes in vapor quality inside the microchannel and velocity field near the inlet and outlet of the nozzle. Spray visualization was carried out at a distance of 4.5 mm from the tip of the microchannel using the high speed visualization system. The experimental results showed that the spray cone angle increased with upstream pressure, and beyond the upstream pressure of 50 bar, the liquid jet flow changed to the cloudy spray flow. The bubble collapse was recorded at upstream pressures of 100 and 120 bar, where the cavitation bubbles extended to the outlet of the microchannel, and their collapse took place around the spray

Numerical 3D flow simulation of attached cavitation structures at ultrasonic horn tips and statistical evaluation of flow aggressiveness via load collectives

Science.gov (United States)

Mottyll, S.; Skoda, R.

2015-12-01

A compressible inviscid flow solver with barotropic cavitation model is applied to two different ultrasonic horn set-ups and compared to hydrophone, shadowgraphy as well as erosion test data. The statistical analysis of single collapse events in wall-adjacent flow regions allows the determination of the flow aggressiveness via load collectives (cumulative event rate vs collapse pressure), which show an exponential decrease in agreement to studies on hydrodynamic cavitation [1]. A post-processing projection of event rate and collapse pressure on a reference grid reduces the grid dependency significantly. In order to evaluate the erosion-sensitive areas a statistical analysis of transient wall loads is utilised. Predicted erosion sensitive areas as well as temporal pressure and vapour volume evolution are in good agreement to the experimental data.

Acoustic methods for cavitation mapping in biomedical applications

Science.gov (United States)

Wan, M.; Xu, S.; Ding, T.; Hu, H.; Liu, R.; Bai, C.; Lu, S.

2015-12-01

In recent years, cavitation is increasingly utilized in a wide range of applications in biomedical field. Monitoring the spatial-temporal evolution of cavitation bubbles is of great significance for efficiency and safety in biomedical applications. In this paper, several acoustic methods for cavitation mapping proposed or modified on the basis of existing work will be presented. The proposed novel ultrasound line-by-line/plane-by-plane method can depict cavitation bubbles distribution with high spatial and temporal resolution and may be developed as a potential standard 2D/3D cavitation field mapping method. The modified ultrafast active cavitation mapping based upon plane wave transmission and reception as well as bubble wavelet and pulse inversion technique can apparently enhance the cavitation to tissue ratio in tissue and further assist in monitoring the cavitation mediated therapy with good spatial and temporal resolution. The methods presented in this paper will be a foundation to promote the research and development of cavitation imaging in non-transparent medium.

Hydrodynamic cavitation as a strategy to enhance the efficiency of lignocellulosic biomass pretreatment

DEFF Research Database (Denmark)

Terán Hilares, Ruly; Ramos, Lucas; da Silva, Silvio Silvério

2018-01-01

to accelerate certain chemical reactions. The application of cavitation energy to enhance the efficiency of lignocellulosic biomass pretreatment is an interesting strategy proposed for integration in biorefineries for the production of bio-based products. Moreover, the use of an HC-assisted process...... was demonstrated as an attractive alternative when compared to other conventional pretreatment technologies. This is not only due to high pretreatment efficiency resulting in high enzymatic digestibility of carbohydrate fraction, but also, by its high energy efficiency, simple configuration, and construction...... of systems, besides the possibility of using on the large scale. This paper gives an overview regarding HC technology and its potential for application on the pretreatment of lignocellulosic biomass. The parameters affecting this process and the perspectives for future developments in this area are also...

Stochastic-field cavitation model

International Nuclear Information System (INIS)

Dumond, J.; Magagnato, F.; Class, A.

2013-01-01

Nonlinear phenomena can often be well described using probability density functions (pdf) and pdf transport models. Traditionally, the simulation of pdf transport requires Monte-Carlo codes based on Lagrangian “particles” or prescribed pdf assumptions including binning techniques. Recently, in the field of combustion, a novel formulation called the stochastic-field method solving pdf transport based on Eulerian fields has been proposed which eliminates the necessity to mix Eulerian and Lagrangian techniques or prescribed pdf assumptions. In the present work, for the first time the stochastic-field method is applied to multi-phase flow and, in particular, to cavitating flow. To validate the proposed stochastic-field cavitation model, two applications are considered. First, sheet cavitation is simulated in a Venturi-type nozzle. The second application is an innovative fluidic diode which exhibits coolant flashing. Agreement with experimental results is obtained for both applications with a fixed set of model constants. The stochastic-field cavitation model captures the wide range of pdf shapes present at different locations

Stochastic-field cavitation model

Science.gov (United States)

Dumond, J.; Magagnato, F.; Class, A.

2013-07-01

Nonlinear phenomena can often be well described using probability density functions (pdf) and pdf transport models. Traditionally, the simulation of pdf transport requires Monte-Carlo codes based on Lagrangian "particles" or prescribed pdf assumptions including binning techniques. Recently, in the field of combustion, a novel formulation called the stochastic-field method solving pdf transport based on Eulerian fields has been proposed which eliminates the necessity to mix Eulerian and Lagrangian techniques or prescribed pdf assumptions. In the present work, for the first time the stochastic-field method is applied to multi-phase flow and, in particular, to cavitating flow. To validate the proposed stochastic-field cavitation model, two applications are considered. First, sheet cavitation is simulated in a Venturi-type nozzle. The second application is an innovative fluidic diode which exhibits coolant flashing. Agreement with experimental results is obtained for both applications with a fixed set of model constants. The stochastic-field cavitation model captures the wide range of pdf shapes present at different locations.

A Multidisciplinary Approach to Mixer-Ejector Analysis and Design

Science.gov (United States)

Hendricks, Eric, S.; Seidel, Jonathan, A.

2012-01-01

The design of an engine for a civil supersonic aircraft presents a difficult multidisciplinary problem to propulsion system engineers. There are numerous competing requirements for the engine, such as to be efficient during cruise while yet quiet enough at takeoff to meet airport noise regulations. The use of mixer-ejector nozzles presents one possible solution to this challenge. However, designing a mixer-ejector which will successfully address both of these concerns is a difficult proposition. Presented in this paper is an integrated multidisciplinary approach to the analysis and design of these systems. A process that uses several low-fidelity tools to evaluate both the performance and acoustics of mixer-ejectors nozzles is described. This process is further expanded to include system-level modeling of engines and aircraft to determine the effects on mission performance and noise near airports. The overall process is developed in the OpenMDAO framework currently being developed by NASA. From the developed process, sample results are given for a notional mixer-ejector design, thereby demonstrating the capabilities of the method.

Periodic cavitation shedding in a cylindrical orifice

Energy Technology Data Exchange (ETDEWEB)

Stanley, C.; Barber, T.; Milton, B.; Rosengarten, G. [University of New South Wales, School of Mechanical and Manufacturing Engineering, Sydney (Australia)

2011-11-15

Cavitation structures in a large-scale (D = 8.25 mm), plain orifice style nozzle within a unique experimental rig are investigated using high-speed visualisation and digital image processing techniques. Refractive index matching with an acrylic nozzle is achieved using aqueous sodium iodide for the test fluid. Cavitation collapse length, unsteady shedding frequency and spray angles are measured for cavitation conditions from incipient to supercavitation for a range of Reynolds numbers, for a fixed L/D ratio of 4.85. Periodic cavitation shedding was shown to occur with frequencies between 500 and 2,000 Hz for conditions in which cavitation occupied less than 30% of the nozzle length. A discontinuity in collapse length was shown to occur once the cavitation exceeded this length, coinciding with a loss of periodic shedding. A mechanism for this behaviour is discussed. Peak spray angles of approximately {theta} {approx} 14 were recorded for supercavitation conditions indicating the positive influence of cavitation bubble collapse on the jet atomisation process. (orig.)

Laser-nucleated acoustic cavitation in focused ultrasound.

Science.gov (United States)

Gerold, Bjoern; Kotopoulis, Spiros; McDougall, Craig; McGloin, David; Postema, Michiel; Prentice, Paul

2011-04-01

Acoustic cavitation can occur in therapeutic applications of high-amplitude focused ultrasound. Studying acoustic cavitation has been challenging, because the onset of nucleation is unpredictable. We hypothesized that acoustic cavitation can be forced to occur at a specific location using a laser to nucleate a microcavity in a pre-established ultrasound field. In this paper we describe a scientific instrument that is dedicated to this outcome, combining a focused ultrasound transducer with a pulsed laser. We present high-speed photographic observations of laser-induced cavitation and laser-nucleated acoustic cavitation, at frame rates of 0.5×10(6) frames per second, from laser pulses of energy above and below the optical breakdown threshold, respectively. Acoustic recordings demonstrated inertial cavitation can be controllably introduced to the ultrasound focus. This technique will contribute to the understanding of cavitation evolution in focused ultrasound including for potential therapeutic applications. © 2011 American Institute of Physics

Cavitation nuclei measurements - A review

International Nuclear Information System (INIS)

Billet, M.L.

1985-01-01

The measurement of cavitation nuclei has been the goal of many cavitation research laboratories and has resulted in the development of many methods. Two significantly different approaches have been developed. One is to measure the particulate-microbubble distribution by utilizing acoustical, electrical or optical methods. The other approach measures a liquid tension and a rate of cavitation events for a liquid in order to establish a cavitation susceptibility. Comparisons between various methods indicate that most methods are capable of giving an indication of the nuclei distribution. Measurements obtained in the ocean environment indicate an average of three bubbles per cubic centimeter are present; whereas, water tunnel bubble distributions vary from much less than one to over a hundred per cubic centimeter

In silico investigation of blast-induced intracranial fluid cavitation as it potentially leads to traumatic brain injury

Science.gov (United States)

Haniff, S.; Taylor, P. A.

2017-11-01

We conducted computational macroscale simulations predicting blast-induced intracranial fluid cavitation possibly leading to brain injury. To further understanding of this problem, we developed microscale models investigating the effects of blast-induced cavitation bubble collapse within white matter axonal fiber bundles of the brain. We model fiber tracks of myelinated axons whose diameters are statistically representative of white matter. Nodes of Ranvier are modeled as unmyelinated sections of axon. Extracellular matrix envelops the axon fiber bundle, and gray matter is placed adjacent to the bundle. Cavitation bubbles are initially placed assuming an intracranial wave has already produced them. Pressure pulses, of varied strengths, are applied to the upper boundary of the gray matter and propagate through the model, inducing bubble collapse. Simulations, conducted using the shock wave physics code CTH, predict an increase in pressure and von Mises stress in axons downstream of the bubbles after collapse. This appears to be the result of hydrodynamic jetting produced during bubble collapse. Interestingly, results predict axon cores suffer significantly lower shear stresses from proximal bubble collapse than does their myelin sheathing. Simulations also predict damage to myelin sheathing, which, if true, degrades axonal electrical transmissibility and general health of the white matter structures in the brain.

Study on velocity distribution in a pool by submersible mixers

International Nuclear Information System (INIS)

Tian, F; Shi, W D; Lu, X N; Chen, B; Jiang, H

2012-01-01

To study the distribution of submersible mixers and agitating effect in the sewage treatment pool, Pro/E software was utilized to build the three-dimensional model. Then, the large-scale computational fluid dynamics software FLUENT6.3 was used. ICEM software was used to build unstructured grid of sewage treatment pool. After that, the sewage treatment pool was numerically simulated by dynamic coordinate system technology and RNG k-ε turbulent model and PIOS algorithm. The macro fluid field and each section velocity flow field distribution were analyzed to observe the efficiency of each submersible mixer. The average velocity and mixing area in the sewage pool were studied simultaneously. Results show that: the preferred project B, two submersible mixers speed is 980 r/min, and setting angles are all 30°. Fluid mixing area in the pool has reached more than 95%. Under the action of two mixers, the fluid in the sewage pool form a continuous circulating water flow. The fluid is mixed adequately and average velocity of fluid in the pool is at around 0.241m/s, which agreed with the work requirements. Consequently it can provide a reference basis for practical engineering application of submersible mixers by using this method.

Investigation of TiO2 photocatalyst performance for decolorization in the presence of hydrodynamic cavitation as hybrid AOP.

Science.gov (United States)

Bethi, Bhaskar; Sonawane, S H; Rohit, G S; Holkar, C R; Pinjari, D V; Bhanvase, B A; Pandit, A B

2016-01-01

In this article, an acoustic cavitation engineered novel approach for the synthesis of TiO2, cerium and Fe doped TiO2 nanophotocatalysts is reported. The prepared TiO2, cerium and Fe doped TiO2 nanophotocatalysts were characterized by XRD and TEM analysis to evaluate its structure and morphology. Photo catalytic performance of undoped TiO2 catalyst was investigated for the decolorization of crystal violet dye in aqueous solution at pH of 6.5 in the presence of hydro dynamic cavitation. Effect of catalyst doping with Fe and Ce was also studied for the decolorization of crystal violet dye. The results shows that, 0.8% of Fe-doped TiO2 exhibits maximum photocatalytic activity in the decolorization study of crystal violet dye due to the presence of Fe in the TiO2 and it may acts as a fenton reagent. Kinetic studies have also been reported for the hybrid AOP (HAOP) that followed the pseudo first-order reaction kinetics. Copyright © 2015 Elsevier B.V. All rights reserved.

The development of mixer machine for organic animal feed production: Proposed study

Science.gov (United States)

Leman, A. M.; Wahab, R. Abdul; Zakaria, Supaat; Feriyanto, Dafit; Nor, M. I. F. Che Mohd; Muzarpar, Syafiq

2017-09-01

Mixer machine plays a major role in producing homogenous composition of animal feed. Long time production, inhomogeneous and minor agglomeration has been observed by existing mixer. Therefore, this paper proposed continuous mixer to enhance mixing efficiency with shorter time of mixing process in order to abbreviate the whole process in animal feed production. Through calculation of torque, torsion, bending, power and energy consumption will perform in mixer machine process. Proposed mixer machine is designed by two layer buckets with purpose for continuity of mixing process. Mixing process was performed by 4 blades which consists of various arm length such as 50, 100,150 and 225 mm in 60 rpm velocity clockwise rotation. Therefore by using this machine will produce the homogenous composition of animal feed through nutrition analysis and short operation time of mixing process approximately of 5 minutes. Therefore, the production of animal feed will suitable for various animals including poultry and aquatic fish. This mixer will available for various organic material in animal feed production. Therefore, this paper will highlights some areas such as continues animal feed supply chain and bio-based animal feed.

A flicker noise/IM3 cancellation technique for active mixer using negative impedance

NARCIS (Netherlands)

Cheng, W.; Annema, Anne J.; Wienk, Gerhardus J.M.; Nauta, Bram

2013-01-01

Abstract—This paper presents an approach to simultaneously cancel flicker noise and IM3 in Gilbert-type mixers, utilizing negative impedances. For proof of concept, two prototype double-balanced mixers in 0.16- m CMOS are fabricated. The first demonstration mixer chip was optimized for full IM3

Conversion Matrix Analysis of SiGe HBT Gilbert Cell Mixers

DEFF Research Database (Denmark)

Johansen, Tom Keinicke; Vidkjær, Jens; Krozer, Viktor

2004-01-01

The frequency response of SiGe HBT active mixers based on the Gilbert cell topology is analyzed theoretically. The time-varying operation of the Gilbert cell mixer is taken into account by applying conversion matrix analysis. The main bandwidth limiting mechanisms experienced in SiGe HBT Gilbert ...

MOSFET-Only Mixer/IIR Filter with Gain using Parametric Amplification

DEFF Research Database (Denmark)

Custódio, José R.; Oliveira, J.; Oliveira, L. B.

2010-01-01

This paper describes the design of a discrete-time passive Mixer/IIR filter. The use of an improved MOS Parametric Amplification leads to a moderate gain in the signal path and improved noise performance, instead of the conversion loss inherent to passive mixers. Simulation results demonstrate th...

Diagnostic Value of Conventional and Digital Radiography for Detection of Cavitated and Non-Cavitated Proximal Caries

Directory of Open Access Journals (Sweden)

Mahdieh Dehghani

2017-02-01

Full Text Available Objectives: This study aimed to assess the diagnostic value of conventional and digital radiography for detection of cavitated and non-cavitated proximal caries.Materials and Methods: Fifty extracted human premolars and molars were mounted in a silicone block. Charge-coupled device (CCD and photostimulable phosphor plate (PSP receptors and intra-oral films were exposed with 60 and 70 kVp with parallel technique. Two observers interpreted the radiographs twice with a two-week interval using a 5-point scale. Teeth were then serially sectioned in mesiodistal direction and evaluated under a stereomicroscope (gold standard. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy were calculated.Results: Sensitivity of all three receptors for detection of enamel lesions was low (5.5-44.4% but it was higher for dentin lesions (42.8-62.8%; PSP with 70 kVp and 0.03s exposure time had the highest sensitivity for enamel lesions, but the difference among receptors was not statistically significant (P>0.05. Sensitivity of all three receptors for detection of non-cavitated lesions was lower than that for cavitated lesions; PSP with 60 kVp and 0.07s exposure time had higher sensitivity and lower patient radiation dose for detection of cavitated and non-cavitated lesions, but the difference was not significant (P>0.05.Conclusions: Digital radiography using PSP receptor with 70 kVp is recommended to detect initial enamel caries. For detection of non-cavitated and cavitated dentin caries, PSP with 60 kVp is more appropriate. Change in kVp did not affect the diagnostic accuracy for detection of caries, and type of receptor was a more important factor.Keywords: Dental Caries; Diagnostic Imaging; Radiography, Dental, Digital

Cavitation and multiphase flow forum - 1985

International Nuclear Information System (INIS)

Hoyt, J.W.; Furuya, O.

1985-01-01

This book presents the papers given at a conference on fluid flow. Topics considered at the conference included cavitation inception, bubble growth, cavitation noise, holography, axial flow pumps, vortices, cavitation erosion, two-phase flow in nozzles, coal slurry valves, hopper flows of granular materials, helium bubble transport in a closed vertical duct, and a numerical model for flow in a venturi scrubber

Twin Screw Mixer/Fine Grind Facility

Data.gov (United States)

Federal Laboratory Consortium — The 40-mm Twin-Screw Mixer/Extruder (TSE) pilot plant is a continuous, remotely operated, flexible facility that can significantly enhance safety and environmental...

CONTINUOUS PRODUCTION OF HYDROXYPROPYL STARCH IN A STATIC MIXER REACTOR

NARCIS (Netherlands)

LAMMERS, G; STAMHUIS, EJ; BEENACKERS, AACM

A novel type of reactor for the chemical derivatization of starch pastes is presented. The design is based on the application of static mixers. The reactor shows excellent plug flow behaviour with a Peclet number of about 100. The viscosity behaviour of concentrated starch pastes in the static mixer

Application of flat plate cavitation data to the analysis of limited cavitation from an isolated triangular surface protrusion

International Nuclear Information System (INIS)

Holl, J.W.

1985-01-01

Isolated surface roughness can cause significant localized pressure reductions which can lead to premature cavitation and degradation of the cavitation performance of a marine vehicle. The characteristic velocity theory was developed to analyze the limited cavitation characteristics of isolated surface protrusions. This theory is dependent upon knowing the boundary layer velocity profile in the vicinity of the roughness and the limited cavitation number for the roughness in a uniform stream. In the investigation described in this paper, the equation for triangular surface protrusions was determined experimentally by testing sharpedged flat plates in a water tunnel. These data were then employed in the characteristic velocity theory to calculate the cavitation characteristics of a triangular protrusion in a turbulent boundary layer for comparison with experimental data

Reflections on cavitation nuclei in water

DEFF Research Database (Denmark)

Mørch, Knud Aage

2007-01-01

to explaining why the tensile strength of water varies so dramatically between the experiments reported. A model for calculation of the critical pressure of skin-covered free gas bubbles as well as that of interfacial gaseous nuclei covered by a skin is presented. This model is able to bridge the apparently......The origin of cavitation bubbles, cavitation nuclei, has been a subject of debate since the early years of cavitation research. This paper presents an analysis of a representative selection of experimental investigations of cavitation inception and the tensile strength of water. At atmospheric...... pressure, the possibility of stabilization of free gas bubbles by a skin has been documented, but only within a range of bubble sizes that makes them responsible for tensile strengths up to about 1.5 bar, and values reaching almost 300 bar have been measured. However, cavitation nuclei can also be harbored...

Numerical Investigation on Aerodynamic and Combustion Performance of Chevron Mixer Inside an Afterburner.

Science.gov (United States)

Yong, Shan; JingZhou, Zhang; Yameng, Wang

2014-11-01

To improve the performance of the afterburner for the turbofan engine, an innovative type of mixer, namely, the chevron mixer, was considered to enhance the mixture between the core flow and the bypass flow. Computational fluid dynamics (CFD) simulations investigated the aerodynamic performances and combustion characteristics of the chevron mixer inside a typical afterburner. Three types of mixer, namely, CC (chevrons tilted into core flow), CB (chevrons tilted into bypass flow), and CA (chevrons tilted into core flow and bypass flow alternately), respectively, were studied on the aerodynamic performances of mixing process. The chevrons arrangement has significant effect on the mixing characteristics and the CA mode seems to be advantageous for the generation of the stronger streamwise vortices with lower aerodynamic loss. Further investigations on combustion characteristics for CA mode were performed. Calculation results reveal that the local temperature distribution at the leading edge section of flame holder is improved under the action of streamwise vortices shedding from chevron mixers. Consequently, the combustion efficiency increased by 3.5% compared with confluent mixer under the same fuel supply scheme.

Design and Fabrication of a Foundry Sand Mixer Using Locally ...

African Journals Online (AJOL)

Most small foundry shops mix their sand manually which is not efficient since homogenous mix cannot be guaranteed and even when foundry mixer are available most of them are imported costing the nation huge foriegn exchange. A foundry sand mixer capable of mixing foundry sand has been designed and fabricated ...

Nucleation and cavitation in parahydrogen

International Nuclear Information System (INIS)

Pi, Martí; Barranco, Manuel; Navarro, Jesús; Ancilotto, Francesco

2012-01-01

Highlights: ► We have constructed a density functional (DF) for parahydrogen between 14 and 32 K. ► The experimental equation of state and the surface tension are well reproduced. ► We have investigated nucleation and cavitations processes in the metastable phase. ► We have obtained the electron bubble explosion within the capillary model. - Abstract: We have used a density functional approach to investigate thermal homogeneous nucleation and cavitation in parahydrogen. The effect of electrons as seeds of heterogeneous cavitation in liquid parahydrogen is also discussed within the capillary model.

Superconducting terahertz mixer using a transition-edge microbolometer

Science.gov (United States)

Prober, D. E.

1993-01-01

We present a new device concept for a mixer element for THz frequencies. This uses a superconducting transition-edge microbridge biased at the center of its superconducting transition near 4.2 K. It is fed from an antenna or waveguide structure. Power from a local oscillator and an RF signal produce a temperature and resulting resistance variation at the difference frequency. The new aspect is the use of a very short bridge in which rapid (less than 0.1 ns) outdiffusion of hot electrons occurs. This gives large intermediate frequency (IF) response. The mixer offers about 4 GHz IF bandwidth, about 80 ohm RF resistive impedance, good match to the IF amplifier, and requires only 1-20 nW of local oscillator power. The upper RF frequency is determined by antenna or waveguide properties. Predicted mixer conversion efficiency is 1/8, and predicted double-sideband receiver noise temperatures are 260 and 90 K for transition widths of 0.1 and 0.5 Tc, respectively.

Side-band-separating heterodyne mixer for band 9 of ALMA.

NARCIS (Netherlands)

Mena, F. P.; Baryshev, A. M.; Kooi, J.; Lodewijk, C. F. J.; Gerlofsma, G.; Hesper, R.; Wild, W.; Shen, XC; Lu, W; Zhang, J; Dou, WB

2006-01-01

Here we present the realization of a side-band-separating (2SB) heterodyne mixer for the frequency range from 602 to 720 GHz (corresponding to ALMA band 9). The mixer, in brief, consists of a quadrature hybrid, two LO injectors, two SIS junctions, and three dumping loads. All the parts were modeled

Cavitation occurrence around ultrasonic dental scalers.

Science.gov (United States)

Felver, Bernhard; King, David C; Lea, Simon C; Price, Gareth J; Damien Walmsley, A

2009-06-01

Ultrasonic scalers are used in dentistry to remove calculus and other contaminants from teeth. One mechanism which may assist in the cleaning is cavitation generated in cooling water around the scaler. The vibratory motion of three designs of scaler tip in a water bath has been characterised by laser vibrometry, and compared with the spatial distribution of cavitation around the scaler tips observed using sonochemiluminescence from a luminol solution. The type of cavitation was confirmed by acoustic emission analysed by a 'Cavimeter' supplied by NPL. A node/antinode vibration pattern was observed, with the maximum displacement of each type of tip occurring at the free end. High levels of cavitation activity occurred in areas surrounding the vibration antinodes, although minimal levels were observed at the free end of the tip. There was also good correlation between vibration amplitude and sonochemiluminescence at other points along the scaler tip. 'Cavimeter' analysis correlated well with luminol observations, suggesting the presence of primarily transient cavitation.

Sandwich-format 3D printed microfluidic mixers: a flexible platform for multi-probe analysis

International Nuclear Information System (INIS)

Kise, Drew P; Reddish, Michael J; Brian Dyer, R

2015-01-01

We report on a microfluidic mixer fabrication platform that increases the versatility and flexibility of mixers for biomolecular applications. A sandwich-format design allows the application of multiple spectroscopic probes to the same mixer. A polymer spacer is ‘sandwiched’ between two transparent windows, creating a closed microfluidic system. The channels of the mixer are defined by regions in the polymer spacer that lack material and therefore the polymer need not be transparent in the spectral region of interest. Suitable window materials such as CaF 2 make the device accessible to a wide range of optical probe wavelengths, from the deep UV to the mid-IR. In this study, we use a commercially available 3D printer to print the polymer spacers to apply three different channel designs into the passive, continuous-flow mixer, and integrated them with three different spectroscopic probes. All three spectroscopic probes are applicable to each mixer without further changes. The sandwich-format mixer coupled with cost-effective 3D printed fabrication techniques could increase the applicability and accessibility of microfluidic mixing to intricate kinetic schemes and monitoring chemical synthesis in cases where only one probe technique proves insufficient. (paper)

The acoustic detection of cavitation in pumps

International Nuclear Information System (INIS)

Macleod, I.D.; Gray, B.S.; Taylor, C.G.

1978-01-01

A programme was initiated to develop a reliable technique for detecting the onset of acoustic noise from cavitation in a pump and to relate this to cavitation inception data, since significant noise from collapse of vapour bubbles arising from such cavitation would reduce the sensitivity of a noise detection system for boiling of sodium in fast breeder reactors. Factors affecting the detection of cavitation are discussed. The instrumentation and techniques of frequency analysis and pulse detection are described. Two examples are then given of the application of acoustic detection techniques under controlled conditions. It is concluded that acoustic detection can be a reliable method for detecting inception of cavitation in a pump and the required conditions are stated. (U.K.)

Airfoil-shaped micro-mixers for reducing fouling on membrane surfaces

Science.gov (United States)

Ho, Clifford K; Altman, Susan J; Clem, Paul G; Hibbs, Michael; Cook, Adam W

2012-10-23

An array of airfoil-shaped micro-mixers that enhances fluid mixing within permeable membrane channels, such as used in reverse-osmosis filtration units, while minimizing additional pressure drop. The enhanced mixing reduces fouling of the membrane surfaces. The airfoil-shaped micro-mixer can also be coated with or comprised of biofouling-resistant (biocidal/germicidal) ingredients.

Development of a micro-mixer-settler for nuclear solvent extraction

International Nuclear Information System (INIS)

Shekhar Kumar; Bijendra Kumar; Sampath, M.; Sivakumar, D.; Kamachi Mudali, U.; Natarajan, R.

2012-01-01

Nuclear solvent extraction was traditionally performed with packed columns, pulse columns, mixer-settlers and centrifugal extractors. However for rapid separations at micro-flow level, micro mixer-settlers were desired and in the past, few of them were actually designed and operated in nuclear solvent extraction research. In the current era of micro-reactor and microchannel devices, there is a renewed interest for micro-mixer-settlers for costly solvents and specialty solutes where small flow-rate is not an issue. In this article, development of a simple but effective micro-mixer-settler for nuclear solvent extraction is reported. The developed unit was tested with 30% TBP/n-dodecane/nitric acid system and in both the regimes of mass transfer c → d (mass transfer from continuous phase to dispersed phase, also written as c → d) and d → c (mass transfer from dispersed phase to continuous phase, also written as d → c) nearly 100% efficiency was observed in extraction as well as stripping modes of operation. (author)

Kaplan turbine tip vortex cavitation - analysis and prevention

Science.gov (United States)

Motycak, L.; Skotak, A.; Kupcik, R.

2012-11-01

The work is focused on one type of Kaplan turbine runner cavitation - a tip vortex cavitation. For detailed description of the tip vortex, the CFD analysis is used. On the basis of this analysis it is possible to estimate the intensity of cavitating vortex core, danger of possible blade surface and runner chamber cavitation pitting. In the paper, the ways how to avoid the pitting effect of the tip vortex are described. In order to prevent the blade surface against pitting, the following possibilities as the change of geometry of the runner blade, dimension of tip clearance and finally the installation of the anti-cavitation lips are discussed. The knowledge of the shape and intensity of the tip vortex helps to design the anti-cavitation lips more sophistically. After all, the results of the model tests of the Kaplan runner with or without anti-cavitation lips and the results of the CFD analysis are compared.

Calculation of lobe mixer flow with reynolds stress model. Oryoku hoteishiki model ni yoru lobe mixer ryu no suchi keisan

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Makoto; Arakawa, Chuichi; Tagori, Tetsuo [Ishikawajima-Harima Heavy Industries, Co., Ltd., Tokyo (Japan) Univ. of Tokyo, Tokyo (Japan). Faculty of Engineering Univ. of Tsukuba, Tsukuba (Japan)

1990-02-25

It is considered that exhaust gas energy of turbofan engine is partly collected to realize the improvement of propulsion efficiency together with the reduction of noise appeared by the change in velocity distribution of exhaust gas flow. Then Lobe mixer was studied and its effectiveness was widely recognized, however the development of more realistic prediction method of exhaust nozzle system including Lobe mixer, is not completed yet. The stress equation model with low Reynolds Number which is easily used by the expansion of Launder Reece Rodi model in three dimension coordinate system was newly constructed. Applicability of the stress equation in more complicated flow field was greatly improved. While the above model was applied to Lobe mixer system, then the qualitative reproduction of mixing process accompanied with flow around Lobe and longitudinal eddy of core or bi-pass flow, was realized. There is room for improvement of pressure strain correlation term and behavior of Reynolds stress very close by wall surface in this model. 16 refs., 9 figs., 1 tab.

Cavitation inception from bubble nuclei

DEFF Research Database (Denmark)

Mørch, Knud Aage

2015-01-01

, and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid....... The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure-time history of the water. A recent model...

Matlab GUI for a Fluid Mixer

Science.gov (United States)

Barbieri, Enrique

2005-01-01

The Test and Engineering Directorate at NASA John C. Stennis Space Center developed an interest to study the modeling, evaluation, and control of a liquid hydrogen (LH2) and gas hydrogen (GH2) mixer subsystem of a ground test facility. This facility carries out comprehensive ground-based testing and certification of liquid rocket engines including the Space Shuttle Main engine. A software simulation environment developed in MATLAB/SIMULINK (M/S) will allow NASA engineers to test rocket engine systems at relatively no cost. In the progress report submitted in February 2004, we described the development of two foundation programs, a reverse look-up application using various interpolation algorithms, a variety of search and return methods, and self-checking methods to reduce the error in returned search results to increase the functionality of the program. The results showed that these efforts were successful. To transfer this technology to engineers who are not familiar with the M/S environment, a four-module GUI was implemented allowing the user to evaluate the mixer model under open-loop and closed-loop conditions. The progress report was based on an udergraduate Honors Thesis by Ms. Jamie Granger Austin in the Department of Electrical Engineering and Computer Science at Tulane University, during January-May 2003, and her continued efforts during August-December 2003. In collaboration with Dr. Hanz Richter and Dr. Fernando Figueroa we published these results in a NASA Tech Brief due to appear this year. Although the original proposal in 2003 did not address other components of the test facility, we decided in the last few months to extend our research and consider a related pressurization tank component as well. This report summarizes the results obtained towards a Graphical User Interface (GUI) for the evaluation and control of the hydrogen mixer subsystem model and for the pressurization tank each taken individually. Further research would combine the two

Released air during vapor and air cavitation

Energy Technology Data Exchange (ETDEWEB)

Jablonská, Jana, E-mail: jana.jablonska@vsb.cz; Kozubková, Milada, E-mail: milada.kozubkova@vsb.cz [VŠB-Technical University of Ostrava, Faculty of Mechanical Engineering, Department of Hydromechanics and Hydraulic Equipment, 17. listopadu 15, 708 33 Ostrava-Poruba (Czech Republic)

2016-06-30

Cavitation today is a very important problem that is solved by means of experimental and mathematical methods. The article deals with the generation of cavitation in convergent divergent nozzle of rectangular cross section. Measurement of pressure, flow rate, temperature, amount of dissolved air in the liquid and visualization of cavitation area using high-speed camera was performed for different flow rates. The measurement results were generalized by dimensionless analysis, which allows easy detection of cavitation in the nozzle. For numerical simulation the multiphase mathematical model of cavitation consisting of water and vapor was created. During verification the disagreement with the measurements for higher flow rates was proved, therefore the model was extended to multiphase mathematical model (water, vapor and air), due to release of dissolved air. For the mathematical modeling the multiphase turbulence RNG k-ε model for low Reynolds number flow with vapor and air cavitation was used. Subsequently the sizes of the cavitation area were verified. In article the inlet pressure and loss coefficient depending on the amount of air added to the mathematical model are evaluated. On the basis of the approach it may be create a methodology to estimate the amount of released air added at the inlet to the modeled area.

Numerical analysis of the texture effect on the hydrodynamic performance of a mechanical seal

Science.gov (United States)

Adjemout, M.; Brunetiere, N.; Bouyer, J.

2016-03-01

The purpose of this paper is to analyze the effect of the main geometrical characteristics of texture on the hydrodynamic lubrication of a mechanical seal. A parametric study was carried out in order to improve the performance of a mechanical seal. The numerical model used in this study solves the Reynolds equation coupled with a mass conservative model which takes into account the cavitation phenomenon. It is shown that among the six dimple shapes tested herein, namely cylinder, square, triangle, truncated cone, truncated pyramid, and spherical cap, the triangular dimples placed symmetrically with respect to their bases are more effective for enhancing the hydrodynamic performance of the mechanical seal. The effect of the area and depth ratios is studied and optimized as well. The optimized solution is able to minimize friction and leakage under a range of operating conditions.

Antenna-coupled 30 THz hot electron bolometer mixers

OpenAIRE

Shcherbatenko, M.; Lobanov, Y.; Benderov, O.; Shurakov, A.; Ignatov, A.; Titova, N.; Finkel, M.; Maslennikov, S.; Kaurova, N.; Voronov, B.M.; Rodin, A.; Klapwijk, T.M.; Gol'tsman, G.N.

2015-01-01

We report on design and characterization of a superconducting Hot Electron Bolometer Mixer integrated with a logarithmic spiral antenna for mid-IR range observations. The antenna parameters have been adjusted to achieve the ultimate performance at 10 ?m (30 THz) range where O3, NH3, CO2, CH4, N2O, …. lines in the Earth’s atmosphere, in planetary atmospheres and in the interstellar space can be observed. The HEB mixer is made of a thin NbN film deposited onto a GaAs substrate. To couple the ra...

Acceptance test report: Field test of mixer pump for 241-AN-107 caustic addition project

International Nuclear Information System (INIS)

Leshikar, G.A.

1997-01-01

The field acceptance test of a 75 HP mixer pump (Hazleton serial number N-20801) installed in Tank 241-AN-107 was conducted from October 1995 thru February 1996. The objectives defined in the acceptance test were successfully met, with two exceptions recorded. The acceptance test encompassed field verification of mixer pump turntable rotation set-up and operation, verification that the pump instrumentation functions within established limits, facilitation of baseline data collection from the mixer pump mounted ultrasonic instrumentation, verification of mixer pump water flush system operation and validation of a procedure for its operation, and several brief test runs (bump) of the mixer pump

Tank 241-AZ-101 Mixer Pump Test Vapor Sampling and Analysis Plan

International Nuclear Information System (INIS)

TEMPLETON, A.M.

2000-01-01

This sampling and analysis plan (SAP) identifies characterization objectives pertaining to sample collection, laboratory analytical evaluation, and reporting requirements for vapor samples obtained during the operation of mixer pumps in tank 241-AZ-101. The primary purpose of the mixer pump test (MPT) is to demonstrate that the two 300 horsepower mixer pumps installed in tank 241-AZ-101 can mobilize the settled sludge so that it can be retrieved for treatment and vitrification. Sampling will be performed in accordance with Tank 241-AZ-101 Mixer Pump Test Data Quality Objective (Banning 1999) and Data Quality Objectives for Regulatory Requirements for Hazardous and Radioactive Air Emissions Sampling and Analysis (Mulkey 1999). The sampling will verify if current air emission estimates used in the permit application are correct and provide information for future air permit applications

Cavitation occurrence around ultrasonic dental scalers

OpenAIRE

Felver, Bernhard; King, David C; Lea, Simon C; Price, Gareth J; Damien Walmsley, A

2009-01-01

Ultrasonic scalers are used in dentistry to remove calculus and other contaminants from teeth. One mechanism which may assist in the cleaning is cavitation generated in cooling water around the scaler. The vibratory motion of three designs of scaler tip in a water bath has been characterised by laser vibrometry, and compared with the spatial distribution of cavitation around the scaler tips observed using sonochemiluminescence from a luminol solution. The type of cavitation was confirmed by a...

Conversion Matrix Analysis of GaAs HEMT Active Gilbert Cell Mixers

DEFF Research Database (Denmark)

Jiang, Chenhui; Johansen, Tom Keinicke; Krozer, Viktor

2006-01-01

In this paper, the nonlinear model of the GaAs HEMT active Gilbert cell mixer is investigated. Based on the model, the conversion gain expression of active Gilbert cell mixers is derived theoretically by using conversion matrix analysis method. The expression is verified by harmonic balance simul...

Low noise Nb-SIS mixers at far above the gap frequency

NARCIS (Netherlands)

Gao, [No Value; vandeStadt, H; Jegers, JBM; Kovtonyuk, S; Hulshoff, W; Whyborn, ND; Klapwijk, TM; deGraauw, T; Liao, FJ; Liu, JY

1996-01-01

There are great interests in developing Nb SIS mixers because of the extremely low noise temperatures and because of the need of low local oscillator (LO) power. Several groups have demonstrated experimentally that Nb SIS mixers with integrated tuning elements can perform near the quantum noise

The inertial properties of pulsing interflow area of counterflow hydrodynamic radiator

Directory of Open Access Journals (Sweden)

Тetyana V. Makarova

2015-12-01

Full Text Available The jet hydrodynamic radiators (HDR are the devices where part of kinetic energy of flooded jet is transformed to pulsations of internal interflow area and flow shell fluctuations. The sound generation process in HDR is involved with its constructional features. Aim: The aim of this work is to study the inertial properties of the HDR pulsating interflow area taking into account its geometric singularities. Materials and Methods: It was proposed to study the pulsating area using the simplified sphere model of pulsating cavitating area of the counterflow type jet hydrodynamic radiator. This radiator can be implemented in two modifications: taking into account the volume that occupies by jet from the nozzle with and without accounting of it. Results: The characteristic dimensions and spatial restrictions are determined for the mentioned modifications based on the research results. The own mass, apparent mass and total mass of pulsating area (pulsator were determined. The dependencies of the corresponding mass relations versus pulsator radius were obtained. Conclusions: It was shown that specifically apparent mass has dominance in total one and it is almost 6 times greater than pulsator own mass. The consideration of the central axial passage occupied by jet out of muzzle increases the contribution of apparent mass to total mass. The influence of apparent mass intensifies under increase of the gas content of dual-phase environment, i.e. under cavitation propagation. The total masses of pulsating area are nearest one to another in various models modifications due to cancellation effect of two factors - increase of pulsator apparent mass and decrease of its own mass under comparatively low sphere volume.

Advanced experimental and numerical techniques for cavitation erosion prediction

CERN Document Server

Chahine, Georges; Franc, Jean-Pierre; Karimi, Ayat

2014-01-01

This book provides a comprehensive treatment of the cavitation erosion phenomenon and state-of-the-art research in the field. It is divided into two parts. Part 1 consists of seven chapters, offering a wide range of computational and experimental approaches to cavitation erosion. It includes a general introduction to cavitation and cavitation erosion, a detailed description of facilities and measurement techniques commonly used in cavitation erosion studies, an extensive presentation of various stages of cavitation damage (including incubation and mass loss), and insights into the contribution of computational methods to the analysis of both fluid and material behavior. The proposed approach is based on a detailed description of impact loads generated by collapsing cavitation bubbles and a physical analysis of the material response to these loads. Part 2 is devoted to a selection of nine papers presented at the International Workshop on Advanced Experimental and Numerical Techniques for Cavitation Erosion (Gr...

A simple image-reject mixer based on two parallel phase modulators

Science.gov (United States)

Hu, Dapeng; Zhao, Shanghong; Zhu, Zihang; Li, Xuan; Qu, Kun; Lin, Tao; Zhang, Kun

2018-02-01

A simple photonic microwave image-reject mixer (IRM) using two parallel phase modulators is proposed. First, a photonic microwave mixer with phase shift ability is achieved using two parallel phase modulators (PMs), an optical bandpass filter, three polarization controllers, three polarization beam splitters and two balanced photodetectors. At the output of the mixer, two frequency downconverted signals with tunable frequency difference can be obtained. By adjusting the phase difference as 90° and utilizing an electrical 90° hybrid, the useless components can be eliminated, and the image reject operation is realized. The key advantage of the proposed scheme is the usage of PM, which avoid the DC bias shifting problem and make the system simple and stable. A simulation is performed to verify the proposed scheme, a relative - 90° or 90° phase shift can be obtained between the two output ports of the photonic microwave mixer, at the output of the IRM, 60 dB image-reject ratio is obtained.

The role of cavitation in liposome formation.

Science.gov (United States)

Richardson, Eric S; Pitt, William G; Woodbury, Dixon J

2007-12-15

Liposome size is a vital parameter of many quantitative biophysical studies. Sonication, or exposure to ultrasound, is used widely to manufacture artificial liposomes, yet little is known about the mechanism by which liposomes are affected by ultrasound. Cavitation, or the oscillation of small gas bubbles in a pressure-varying field, has been shown to be responsible for many biophysical effects of ultrasound on cells. In this study, we correlate the presence and type of cavitation with a decrease in liposome size. Aqueous lipid suspensions surrounding a hydrophone were exposed to various intensities of ultrasound and hydrostatic pressures before measuring their size distribution with dynamic light scattering. As expected, increasing ultrasound intensity at atmospheric pressure decreased the average liposome diameter. The presence of collapse cavitation was manifested in the acoustic spectrum at high ultrasonic intensities. Increasing hydrostatic pressure was shown to inhibit the presence of collapse cavitation. Collapse cavitation, however, did not correlate with decreases in liposome size, as changes in size still occurred when collapse cavitation was inhibited either by lowering ultrasound intensity or by increasing static pressure. We propose a mechanism whereby stable cavitation, another type of cavitation present in sound fields, causes fluid shearing of liposomes and reduction of liposome size. A mathematical model was developed based on the Rayleigh-Plesset equation of bubble dynamics and principles of acoustic microstreaming to estimate the shear field magnitude around an oscillating bubble. This model predicts the ultrasound intensities and pressures needed to create shear fields sufficient to cause liposome size change, and correlates well with our experimental data.

PEMISAHAN Zr – Hf SECARA SINAMBUNG MENGGUNAKAN MIXER SETTLER

Directory of Open Access Journals (Sweden)

Dwi Biyantoro

2017-01-01

Full Text Available ABSTRAK PEMISAHAN Zr – Hf SECARA SINAMBUNG MENGGUNAKANMIXER SETTLER. Telah dilakukan pemisahanZr – Hf secara sinambung menggunakan pengaduk pengenap (mixer settler 16 stage. Larutan umpan adalah zirkon nitrat dengan kadar Zr = 30786 ppm dan Hf = 499 ppm. Ekstraktan dipakai adalah solven 60 % TBP dalam kerosen dan larutan scrubbingyang dipakai adalah asam nitrat 1 M. Umpan masuk pada stageke 5 dikontakkan secara berlawanan arah dengan solven masuk pada stage ke 16 dan larutan scrubbing masuk pada stage ke 1. Tujuan penelitian ini adalah memisahkan unsur Zr dan Hf dari hasil olah pasir zirkon menggunakan solven TBP dengan alat mixer settler16 stage. Analisis umpan dan hasil proses pemisahan untuk zirkonium (Zr dilakukan dengan menggunakan alat pendar sinar-X, sedangkananalisis unsur hafnium (Hf menggunakan Analisis Pengaktifan Neutron (APN. Parameter penelitian dilakukan dengan variasi keasaman asam nitrat dalam umpan dan variasi waktu pada berbagai laju pengadukan. Hasil penelitian pemisahan unsur Zr dengan Hf diperolehkondisi optimum pada keasaman umpan 4 N HNO3, keseimbangan dicapai setelah 3jam dan laju pengadukan 3300 rpm. Hasil ekstrak  unsur zirkon (Zr diperoleh kadar sebesar 28577 ppm dengan efisiensi 92,76 % serta kadar pengotor hafnium (Hf sebesar 95 ppm. Kata Kunci: pemisahan Zr, Hf, ekstraksi, mixer settler, alat pendar sinar-X, APN. ABSTRACT SEPARATION of Zr - Hf CONTINUOUSLY USE THE MIXER SETTLER. Separation of Zr - Hf continuously using mixer settler 16 stage has been done. The feed solution is zircon nitrate concentration of Zr = 30786 ppm  and Hf = 499 ppm. As the solvent used extractant 60 % TBP in 40 % kerosene. Nitric acid solution used srubbing 1 M. The feed entered into stage to 5 is contacted with solvents direction on the stage to 16 and the scrubbing solution enter the stage to 1. The purpose of this study is to separate Zr and Hf of the results from the process of zircon sand using solvent TBP using 16 stage

Safety basis for the 241-AN-107 mixer pump installation and caustic addition

International Nuclear Information System (INIS)

Van Vleet, R.J.

1994-01-01

This safety Basis was prepared to determine whether or not the proposed activities of installing a 76 HP jet mixer pump and the addition of approximately 50,000 gallons of 19 M (50:50 wt %) aqueous caustic are within the safety envelope as described by Tank Farms (chapter six of WHC-SD-WM-ISB-001, Rev. 0). The safety basis covers the components, structures and systems for the caustic addition and mixer pump installation. These include: installation of the mixer pump and monitoring equipment; operation of the mixer pump, process monitoring equipment and caustic addition; the pump stand, caustic addition skid, the electrical skid, the video camera system and the two densitometers. Also covered is the removal and decontamination of the mixer pump and process monitoring system. Authority for this safety basis is WHC-IP-0842 (Waste Tank Administration). Section 15.9, Rev. 2 (Unreviewed Safety Questions) of WHC-IP-0842 requires that an evaluation be performed for all physical modifications

Compact terahertz passive spectrometer with wideband superconductor-insulator-superconductor mixer.

Science.gov (United States)

Kikuchi, K; Kohjiro, S; Yamada, T; Shimizu, N; Wakatsuki, A

2012-02-01

We developed a compact terahertz (THz) spectrometer with a superconductor-insulator-superconductor (SIS) mixer, aiming to realize a portable and highly sensitive spectrometer to detect dangerous gases at disaster sites. The receiver cryostat which incorporates the SIS mixer and a small cryocooler except for a helium compressor has a weight of 27 kg and dimensions of 200 mm × 270 mm × 690 mm. In spite of the small cooling capacity of the cryocooler, the SIS mixer is successfully cooled lower than 4 K, and the temperature variation is suppressed for the sensitive measurement. By adopting a frequency sweeping system using photonic local oscillator, we demonstrated a spectroscopic measurement of CH(3)CN gas in 0.2-0.5 THz range.

Development of novel micro swirl mixer for producing fine metal oxide nanoparticles by continuous supercritical hydrothermal method.

Science.gov (United States)

Kawasaki, Shin-ichiro; Sue, Kiwamu; Ookawara, Ryuto; Wakashima, Yuichiro; Suzuki, Akira

2010-01-01

Novel micro swirl mixers were developed to synthesize nanoparticles, and the effect of their mixing performance on the characteristics of the synthesized nanoparticles was determined. The results were compared with those obtained using simple T-shaped mixers under the same reaction conditions. The synthesis of NiO, whose characteristics depend on the mixing performance of the mixer, was chosen as a model reaction. Initial investigations highlighted that the average particle size decreased from 32 to 23 to 20 nm as the inner diameter of the swirl mixers was decreased from 3.2 mm (Swirl mixer, SM-3.2) to 0.8 mm (Micro swirl mixer, MSM-0.8) to 0.5 mm (Micro swirl mixer, MSM-0.5), respectively. On the other hand, a similar decrease in the average particle size from 34 to 20 nm was observed with a decrease in the inner diameter of the T-shaped mixers from 1.3 mm (Tee union, T-1.3) to 0.3 mm (Micro tee union, T-0.3), respectively. Further, narrow particle size distributions were observed with a decrease in the inner diameter of each mixer. Furthermore, a computational fluid dynamics (CFD) simulation indicated an excellent mixing mechanism, which contributed to the improvement in the heating rate and the formation of nanoparticles of smaller size with a narrow particle size distribution. The result presented here indicates that the micro swirl mixers produce high-quality metal oxide nanoparticles. The size of the obtained particles with improved size distributions was comparable to that of the particles obtained using the T-shaped mixers, although the inner diameter of the swirl mixers was larger. Therefore, preliminary evidence suggests that the swirl flow mixers have the ability to produce rapid and homogeneous fluid mixing, thus controlling the particle size.

Actual status of sodium cavitation studies in Japan

International Nuclear Information System (INIS)

Yamamoto, K.; Kamiyama, S.; Hashimoto, H.; Mochizuki, K.; Nakai, Y.; Ishibashi, E.; Tamaoki, T.

1976-01-01

A cavitation test has been conducted on some components of the fast experimental reactor JOYO. Design is in progress for the fast proto-type reactor MONJU. Deliberate consideration has been taken against cavitation as this reactor will be operated under severer service conditions than that of JOYO. A cavitation test of entrance nozzles of MONJU fuel subassemblies was performed in water. In order to obtain design data a program of cavitation tests is planned

A Calculation of hydrodynamic noise of control valve on instrumentation and control system using smart plant

International Nuclear Information System (INIS)

Demon Handoyo; Djoko H Nugroho

2012-01-01

It has been calculated characteristics of the control valve Instrumentation and Control Systems using Smart Plant software. This calculation is done in order to control the valve that will be installed as part of the instrumentation and control systems to provide the performance according to the design. The characteristics that have been calculated are Reynolds number factors which are related to the flow regime in the valve. Critical pressure factor, Valve Hydrodynamic cavitation and noise index. In this paper the discussion will be limited to matters relating to Hydrodynamic noise generation process using model of the instrumentation and control system in the plant design in yellow cake PIPKPP activities in 2012. The results of the calculation of the noise on the valves design are in the range between 9.58~70.1 dBA. (author)

A niobiumnitride mixer with niobium tuning circuit

International Nuclear Information System (INIS)

Plathner, B.; Schicke, M.; Lehnert, T.; Gundlach, K.H.; Rothermel, H.; Aoyagi, M.; Takada, S.

1996-01-01

This letter reports a low noise submillimeter-wave mixer using NbN tunnel junctions integrated in Nb matching circuits. The double side band receiver noise temperature was 245 K at 345 GHz. Plasma conditions for NbN film deposition on quartz substrates at room temperature are created by using a second Nb target as a selective nitrogen pump. Electrodes for tunnel junctions with critical temperatures above 15 K and normal state resistivities in the range from 130 to 160 μΩcm were obtained. This permits integrating NbN junctions into normal metal or non-NbN superconducting matching circuits, which is of great interest for THz mixers. copyright 1996 American Institute of Physics

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.

Some observations of tip-vortex cavitation

Science.gov (United States)

Arndt, R. E. A.; Arakeri, V. H.; Higuchi, H.

1991-08-01

Cavitation has been observed in the trailing vortex system of an elliptic platform hydrofoil. A complex dependence on Reynolds number and gas content is noted at inception. Some of the observations can be related to tension effects associated with the lack of sufficiently large-sized nuclei. Inception measurements are compared with estimates of pressure in the vortex obtained from LDV measurements of velocity within the vortex. It is concluded that a complete correlation is not possible without knowledge of the fluctuating levels of pressure in tip-vortex flows. When cavitation is fully developed, the observed tip-vortex trajectory flows. When cavitation is fully developed, the observed tip-vortex trajectory shows a surprising lack of dependence on any of the physical parameters varied, such as angle of attack, Reynolds number, cavitation number, and dissolved gas content.

JPRS Report, Science & Technology, USSR: Chemistry.

Science.gov (United States)

1988-07-06

During Hydrodynamic Cavitation [A. V. Yefimov, G.A. Vorobyev; ZHURNAL FIZICHESKOY KHIMII No 1, Jan 88] 7 COMBUSTION AND EXPLOSIVES Suppression of...RSR", 1988 12770 Microhits and Luminescent Flashes During Hydrodynamic Cavitation 18410249b Moscow ZHURNAL FIZICHESKOY KHIMII in Russian Vol 62, No...monitor the occurrence of hydrodynamic cavitation and make an online estimate of its erosion activity by using devices based on photomultiplier tubes

On-line separation of iodine species in reactor water using mixer-settlers

International Nuclear Information System (INIS)

Malmbeck, R.; Skarnemark, G.

1995-01-01

A method for separation of iodine species from water has been developed. It is based on liquid-liquid extraction and separation is achieved in four extraction steps. A system based on this method for continuous separation of iodine species using mixer-settlers has been developed. It consists of four mixer-settler batteries with 4,4,6 and 6 mixer-settler stages each. As organic phase an aliphatic kerosene is used and the separation is improved if the organic solvent has been pretreated with iodine carrier, stripped and washed. With an aqueous feed flowrate of 10 ml/min and mixer-settler battery phase flowratios of approximately 0.1 except for the elementary iodine strip battery with a phase flowratio of 1, the system separation performance is 92% for methyl iodide, 97% for iodate and elementary iodine and 99% for iodide. (orig.)

Continuous mixer, process and use in a pumping plant for a high viscosity fluid

Energy Technology Data Exchange (ETDEWEB)

Cholet, H.

1993-03-12

The invention concerns a novel continuous mixer comprising a rotary shaft carrying two or more vanes for mixing two or more fluids of different viscosities supplied at the inlet of the mixer body and for providing, at the mixer body outlet, a mixture of viscosity lower than that of the more or most viscous fluid. Preferentially, the vane profile is such that, without fluid circulation, rotation of the vanes produces a reaction force parallel to the rotational axis and in the same direction as the resulting flow or does not produce a reaction force of significant magnitude parallel to the rotational axis. The mixer shaft is connected to a pump shaft which is rotated by hydraulic motor driven by pressurized fluid injection. The mixer is used especially for facilitating viscous crude oil pumping from directional wells including horizontal or inclined portions.

Regulating Ultrasound Cavitation in order to Induce Reproducible Sonoporation

Science.gov (United States)

Mestas, J.-L.; Alberti, L.; El Maalouf, J.; Béra, J.-C.; Gilles, B.

2010-03-01

Sonoporation would be linked to cavitation, which generally appears to be a non reproducible and unstationary phenomenon. In order to obtain an acceptable trade-off between cell mortality and transfection, a regulated cavitation generator based on an acoustical cavitation measurement was developed and tested. The medium to be sonicated is placed in a sample tray. This tray is immersed in in degassed water and positioned above the face of a flat ultrasonic transducer (frequency: 445 kHz; intensity range: 0.08-1.09 W/cm2). This technical configuration was admitted to be conducive to standing-wave generation through reflection at the air/medium interface in the well thus enhancing the cavitation phenomenon. Laterally to the transducer, a homemade hydrophone was oriented to receive the acoustical signal from the bubbles. From this spectral signal recorded at intervals of 5 ms, a cavitation index was calculated as the mean of the cavitation spectrum integration in a logarithmic scale, and the excitation power is automatically corrected. The device generates stable and reproducible cavitation level for a wide range of cavitation setpoint from stable cavitation condition up to full-developed inertial cavitation. For the ultrasound intensity range used, the time delay of the response is lower than 200 ms. The cavitation regulation device was evaluated in terms of chemical bubble collapse effect. Hydroxyl radical production was measured on terephthalic acid solutions. In open loop, the results present a great variability whatever the excitation power. On the contrary the closed loop allows a great reproducibility. This device was implemented for study of sonodynamic effect. The regulation provides more reproducible results independent of cell medium and experimental conditions (temperature, pressure). Other applications of this regulated cavitation device concern internalization of different particles (Quantum Dot) molecules (SiRNA) or plasmids (GFP, DsRed) into different

Observations on Rotating Cavitation and Cavitation Surge From The Development of the Fastrac Engine Turbopump

Science.gov (United States)

Zoladz, Thomas F.; Turner, James E. (Technical Monitor)

2000-01-01

The effects of rotating cavitation and cavitation surges on the Fastrac Engine Turbopump are described in a viewgraph presentation format. The bent inducer blade dilemma and observations of unsteady data and oscillation components are discussed. The pump-feed system stability modeling assessment is outlined. Recommendations are made urging further investigation.

Seasonality of cavitation and frost fatigue in Acer mono Maxim.

Science.gov (United States)

Zhang, Wen; Feng, Feng; Tyree, Melvin T

2017-12-08

Although cavitation is common in plants, it is unknown whether the cavitation resistance of xylem is seasonally constant or variable. We tested the changes in cavitation resistance of Acer mono before and after a controlled cavitation-refilling and freeze-thaw cycles for a whole year. Cavitation resistance was determined from 'vulnerability curves' showing the percent loss of conductivity versus xylem tension. Cavitation fatigue was defined as a reduction of cavitation resistance following a cavitation-refilling cycle, whereas frost fatigue was caused by a freeze-thaw cycle. A. mono developed seasonal changes in native embolisms; values were relatively high during winter but relatively low and constant throughout the growing season. Cavitation fatigue occurred and changed seasonally during the 12-month cycle; the greatest fatigue response occurred during summer and the weakest during winter, and the transitions occurred during spring and autumn. A. mono was highly resistant to frost damage during the relatively mild winter months; however, a quite different situation occurred during the growing season, as the seasonal trend of frost fatigue was strikingly similar to that of cavitation fatigue. Seasonality changes in cavitation resistance may be caused by seasonal changes in the mechanical properties of the pit membranes. © 2017 John Wiley & Sons Ltd.

Cavitation damage of ceramics

International Nuclear Information System (INIS)

Kovalenko, V.I.; Marinin, V.G.

1988-01-01

Consideration is given to results of investigation of ceramic material damage under the effect of cavitation field on their surface, formed in water under the face of exponential concentrator, connected with ultrasonic generator UZY-3-0.4. Amplitude of vibrations of concentrator face (30+-2)x10 -6 m, frequency-21 kHz. It was established that ceramics resistance to cavitation effect correlated with the product of critical of stress intensity factor and material hardness

Measuring Cavitation with Synchrotron X-Rays

Science.gov (United States)

Duke, Daniel; Kastengren, Alan; Powell, Chris; X-Ray Fuel Spray Group, Energy Systems Division Team

2012-11-01

Cavitation plays an important role in the formation of sprays from small nozzles such as those found in fuel injection systems. A sharp-edged inlet from the sac into the nozzle of a diesel fuel injector is shown to inititate a strong sheet-like cavitation along the boundary layer of the nozzle throat, which is difficult to measure and can lead to acoustic damage. To investigate this phenomenon, a diagnostic technique capable of mapping the density field of the nozzle through regions of intense cavitation is required. Available visible-light techniques are limited to qualitative observations of the outer extent of cavitation zones. However, brilliant X-rays from a synchrotron source have negligible refraction and are capable of penetrating the full extent of cavitation zones. We present the early results of a novel application of line-of-sight, time-resolved X-ray radiography on a cavitating model nozzle. Experiments were conducted at Sector 7-BM of the Advanced Photon Source. Density and vapor distribution are measured from the quantitative absorption of monochromatic X-rays. The density field can then be tomographically reconstructed from the projections. The density is then validated against a range of compressible and incompressible numerical simulations. This research was performed at the 7-BM beamline of the Advanced Photon Source. We acknowledge the support of the U.S. Department of Energy under Contract No. DE-AC02-06CH11357 and the DOE Vehicle Technologies Program (DOE-EERE).

Drag Reducing and Cavitation Resistant Coatings

Energy Technology Data Exchange (ETDEWEB)

Pease, Leonard F.

2016-12-28

Client, Green Building Systems (GBS), presented PNNL a coating reported to reduce drag and prevent cavitation damage on marine vessels, turbines and pumps. The composition of the coating remains proprietary but has as constituents including silicon oxides, aliphatic carbon chains, and fluorine rich particles. The coating is spray applied to surfaces. Prior GBS testing and experiments suggest reduction of both drag and cavitation on industrial scale propellers, but the underlying mechanism for these effects remains unclear. Yet, the application is compelling because even modest reductions in drag to marine vessels and cavitation to propellers and turbines present a significant economic and environmental opportunity. To discern among possible mechanisms, PNNL considered possible mechanisms with the client, executed multiple experiments, and completed one theoretical analysis (see appendix). The remainder of this report first considers image analysis to gain insight into drag reduction mechanisms and then exposes the coating to cavitation to explore its response to an intensely cavitating environment. Although further efforts may be warranted to confirm mechanisms, this report presents a first investigation into these coatings within the scope and resources of the technology assistance program (TAP).

The modeling of continuous mixers. Part I: The corotating twin-screw extruder

NARCIS (Netherlands)

Meijer, H.E.H.; Elemans, P.H.M.

1988-01-01

In many operations in polymer processing, such as polymer blending, devolatilization, or incorporation of fillers in a polymeric matrix, continuous mixers are used; e.g., corotating twin-screw extruders (ZSK), Buss Cokneaders and Farrel Continuous Mixers. Theoretical analysis of these machines tends

The Strength Analysis of Differential Planetary Gears of Gearbox for Concrete Mixer Truck

Science.gov (United States)

Bae, M. H.; Bae, T. Y.; Kim, D. J.

2018-03-01

The power train of mixer gearbox for concrete mixer truck includes differential planetary gears to get large reduction ratio for operating mixer a drum and simple structure. The planetary gears are very important part of a mixer gearbox where strength problems namely gear bending stress, gear compressive stress and scoring failure are the main concern. In the present study, calculating specifications of the differential planetary gears and analyzing the gear bending and compressive stresses as well as scoring factor of the differential planetary gears gearbox for an optimal design of the mixer gearbox in respect to cost and reliability are investigated. The analyses of actual gear bending and compressive stresses of the differential planetary gears using Lewes & Hertz equation and verifications of the calculated specifications of the differential planetary gears evaluate the results with the data of allowable bending and compressive stress from the Stress-No. of cycles curves of gears. In addition, we also analyze actual gear scoring factor as well as evaluate the possibility of scoring failure of the differential planetary gear.

Laser-induced cavitation based micropump

NARCIS (Netherlands)

Dijkink, R.J.; Ohl, C.D.

2008-01-01

Lab-on-a-chip devices are in strong demand as versatile and robust pumping techniques. Here, we present a cavitation based technique, which is able to pump a volume of 4000 m3 within 75 s against an estimated pressure head of 3 bar. The single cavitation event is created by focusing a laser pulse in

Characterization of Axial Inducer Cavitation Instabilities via High Speed Video Recordings

Science.gov (United States)

Arellano, Patrick; Peneda, Marinelle; Ferguson, Thomas; Zoladz, Thomas

2011-01-01

Sub-scale water tests were undertaken to assess the viability of utilizing high resolution, high frame-rate digital video recordings of a liquid rocket engine turbopump axial inducer to characterize cavitation instabilities. These high speed video (HSV) images of various cavitation phenomena, including higher order cavitation, rotating cavitation, alternating blade cavitation, and asymmetric cavitation, as well as non-cavitating flows for comparison, were recorded from various orientations through an acrylic tunnel using one and two cameras at digital recording rates ranging from 6,000 to 15,700 frames per second. The physical characteristics of these cavitation forms, including the mechanisms that define the cavitation frequency, were identified. Additionally, these images showed how the cavitation forms changed and transitioned from one type (tip vortex) to another (sheet cavitation) as the inducer boundary conditions (inlet pressures) were changed. Image processing techniques were developed which tracked the formation and collapse of cavitating fluid in a specified target area, both in the temporal and frequency domains, in order to characterize the cavitation instability frequency. The accuracy of the analysis techniques was found to be very dependent on target size for higher order cavitation, but much less so for the other phenomena. Tunnel-mounted piezoelectric, dynamic pressure transducers were present throughout these tests and were used as references in correlating the results obtained by image processing. Results showed good agreement between image processing and dynamic pressure spectral data. The test set-up, test program, and test results including H-Q and suction performance, dynamic environment and cavitation characterization, and image processing techniques and results will be discussed.

Comparison of Different Mathematical Models of Cavitation

Directory of Open Access Journals (Sweden)

Dorota HOMA

2014-12-01

Full Text Available Cavitation occurs during the flow when local pressure drops to the saturation pressure according to the temperature of the flow. It includes both evaporation and condensation of the vapor bubbles, which occur alternately with high frequency. Cavitation can be very dangerous, especially for pumps, because it leads to break of flow continuity, noise, vibration, erosion of blades and change in pump’s characteristics. Therefore it is very important for pump designers and users to avoid working in cavitation conditions. Simulation of flow can be very useful in that and can indicate if there is risk of cavitating flow occurrence. As this is a multiphase flow and quite complicated phenomena, there are a few mathematical models describing it. The aim of this paper is to make a short review of them and describe their approach to model cavitation. It is desirable to know differences between them to model this phenomenon properly.

Kaplan turbine tip vortex cavitation – analysis and prevention

International Nuclear Information System (INIS)

Motycak, L; Skotak, A; Kupcik, R

2012-01-01

The work is focused on one type of Kaplan turbine runner cavitation – a tip vortex cavitation. For detailed description of the tip vortex, the CFD analysis is used. On the basis of this analysis it is possible to estimate the intensity of cavitating vortex core, danger of possible blade surface and runner chamber cavitation pitting. In the paper, the ways how to avoid the pitting effect of the tip vortex are described. In order to prevent the blade surface against pitting, the following possibilities as the change of geometry of the runner blade, dimension of tip clearance and finally the installation of the anti-cavitation lips are discussed. The knowledge of the shape and intensity of the tip vortex helps to design the anti-cavitation lips more sophistically. After all, the results of the model tests of the Kaplan runner with or without anti-cavitation lips and the results of the CFD analysis are compared.