Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-4682
Takanori Yoshimoto, T. Kanagawa
This study theoretically investigates plane progressive quasi-monochromatic waves in an initially quiescent compressible liquid containing many spherical gas bubbles, on the basis of the derivation of a nonlinear wave equation that represents waves propagating at a high phase velocity induced by taking the effect of liquid compressibility in consideration. The governing equations for bubbly flows are composed of the conservation equations of mass and momentum, the equation of bubble dynamics as radial oscillations, and so on. By using the method of multiple scales with an appropriate choice of set of scaling relations of nondimensional parameters, the nonlinear Schrödinger (NLS) equation with an attenuation term and some correction terms can be derived from the governing equations. The decrease in the group velocity in a far field is then clarified. The dependence of waveform on wavenumber is implied.
{"title":"Weakly Nonlinear and High Speed Propagation of Quasi-Monochromatic High Frequency Waves in Compressible Bubbly Liquids","authors":"Takanori Yoshimoto, T. Kanagawa","doi":"10.1115/ajkfluids2019-4682","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4682","url":null,"abstract":"\u0000 This study theoretically investigates plane progressive quasi-monochromatic waves in an initially quiescent compressible liquid containing many spherical gas bubbles, on the basis of the derivation of a nonlinear wave equation that represents waves propagating at a high phase velocity induced by taking the effect of liquid compressibility in consideration. The governing equations for bubbly flows are composed of the conservation equations of mass and momentum, the equation of bubble dynamics as radial oscillations, and so on. By using the method of multiple scales with an appropriate choice of set of scaling relations of nondimensional parameters, the nonlinear Schrödinger (NLS) equation with an attenuation term and some correction terms can be derived from the governing equations. The decrease in the group velocity in a far field is then clarified. The dependence of waveform on wavenumber is implied.","PeriodicalId":322380,"journal":{"name":"Volume 5: Multiphase Flow","volume":"206 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132235969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-28DOI: 10.1115/ajkfluids2019-5091
Roy A. Pillers, T. Morgan, T. Heindel, D. Estanga
Natural gas hydrates form under high pressure and low-temperature environments common in deepwater off-shore petroleum production operations. Once hydrates form, they can agglomerate and deposit resulting in solid plugs within the piping system, which could require extensive downtime for remediation and recommission of the systems. Hydrate plug formation is difficult to characterize because of the challenging environments in which they form, the lack of instrumentation for such environments, and the fast reaction time compared to other blocking mechanisms. This study explores the use of X-ray flow visualization, including X-ray radiography and X-ray computed tomography, to help characterize hydrate formation in a laboratory setting. A structure II hydrate was formed in a concentric cylinder mixing tank where a mixture of distilled water and cyclopentane was stirred in the inner tank while the outer tank was cooled. As the tank cooled, the distilled water-cyclopentane mixture converted to hydrate, which was captured with X-ray radiographic videos. Once formed, X-ray computed tomography images were acquired to gather 3D reconstructed images of the hydrate with and without liquid present in the mixing tank. It was shown that X-ray imaging could provide a qualitative assessment of hydrate formation. Quantitative measures were challenging because of the limited contrast between the hydrate and liquid region.
{"title":"X-Ray Flow Visualization of Cyclopentane Hydrate Formation","authors":"Roy A. Pillers, T. Morgan, T. Heindel, D. Estanga","doi":"10.1115/ajkfluids2019-5091","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5091","url":null,"abstract":"\u0000 Natural gas hydrates form under high pressure and low-temperature environments common in deepwater off-shore petroleum production operations. Once hydrates form, they can agglomerate and deposit resulting in solid plugs within the piping system, which could require extensive downtime for remediation and recommission of the systems. Hydrate plug formation is difficult to characterize because of the challenging environments in which they form, the lack of instrumentation for such environments, and the fast reaction time compared to other blocking mechanisms. This study explores the use of X-ray flow visualization, including X-ray radiography and X-ray computed tomography, to help characterize hydrate formation in a laboratory setting. A structure II hydrate was formed in a concentric cylinder mixing tank where a mixture of distilled water and cyclopentane was stirred in the inner tank while the outer tank was cooled. As the tank cooled, the distilled water-cyclopentane mixture converted to hydrate, which was captured with X-ray radiographic videos. Once formed, X-ray computed tomography images were acquired to gather 3D reconstructed images of the hydrate with and without liquid present in the mixing tank. It was shown that X-ray imaging could provide a qualitative assessment of hydrate formation. Quantitative measures were challenging because of the limited contrast between the hydrate and liquid region.","PeriodicalId":322380,"journal":{"name":"Volume 5: Multiphase Flow","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122950173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-28DOI: 10.1115/ajkfluids2019-5587
S. Karimi, Jun Zhang, S. Shirazi, B. McLaury
The effects of particle size on erosion magnitude and erosion profiles are investigated experimentally in a submerged slurry jet impingement facility. The slurries were diluted to avoid concentration effects on the flow field and the resulting erosion. The experiments are performed with particle sizes of 25, 75, 150, 300, and 600 μm. Experimental results demonstrate different erosion severity and pattern for the various particle sizes. It is critical to have a reliable and accurate tool to predict erosion for different particle sizes. Previously, a comprehensive CFD-based procedure to predict erosion for various particle sizes was proposed by investigators at the Erosion/Corrosion Research Center (E/CRC). A feature of this procedure is that it can account for particle size in more detail than previous methods. In this study, the computational procedure is applied to conditions of the present experimental data. Particle impact parameters are extracted to explain the effect of particle size on the resulting erosion. The predicted results are compared with data which demonstrate possible shortcomings of the available CFD based techniques for predicting solid particle erosion. The results indicate that with proper use of grid spacing near the wall, the CFD-based erosion calculation method with existing erosion models can predict the trend of the experimental data, though improvements are still needed to the models to accurately account for particle size effects.
{"title":"Evaluation of the Effect of Particle Size on Erosion Calculations Utilizing CFD and Comparison With Submerged Slurry Jet Experiments","authors":"S. Karimi, Jun Zhang, S. Shirazi, B. McLaury","doi":"10.1115/ajkfluids2019-5587","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5587","url":null,"abstract":"\u0000 The effects of particle size on erosion magnitude and erosion profiles are investigated experimentally in a submerged slurry jet impingement facility. The slurries were diluted to avoid concentration effects on the flow field and the resulting erosion. The experiments are performed with particle sizes of 25, 75, 150, 300, and 600 μm. Experimental results demonstrate different erosion severity and pattern for the various particle sizes. It is critical to have a reliable and accurate tool to predict erosion for different particle sizes. Previously, a comprehensive CFD-based procedure to predict erosion for various particle sizes was proposed by investigators at the Erosion/Corrosion Research Center (E/CRC). A feature of this procedure is that it can account for particle size in more detail than previous methods. In this study, the computational procedure is applied to conditions of the present experimental data. Particle impact parameters are extracted to explain the effect of particle size on the resulting erosion. The predicted results are compared with data which demonstrate possible shortcomings of the available CFD based techniques for predicting solid particle erosion. The results indicate that with proper use of grid spacing near the wall, the CFD-based erosion calculation method with existing erosion models can predict the trend of the experimental data, though improvements are still needed to the models to accurately account for particle size effects.","PeriodicalId":322380,"journal":{"name":"Volume 5: Multiphase Flow","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126814972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-28DOI: 10.1115/ajkfluids2019-5395
V. Matoušek, R. Visintainer, J. Furlan, A. Sellgren
Pipe flows of bimodal settling slurries exhibit frictional head losses quite different from those determined simply as a sum of loss contributions by the individual fractions. Mechanisms governing flow friction and resulting from an interaction of grains of different fractions in transported slurry are not well understood. This makes a prediction of the frictional head loss in flows of bimodal slurries with Newtonian carrier uncertain. An extensive experimental campaign was conducted in GIW Hydraulic Laboratory in 2016 with slurries of four narrow graded fractions of the virtually same grain densities and very different grain sizes (carrier-liquid fraction, pseudo-homogeneous-, heterogeneous-, and stratified fractions). Besides testing of the individual fractions, different combinations of the fraction mixtures (bimodal, three- and four-component) were tested as well. In our previous work published in 2018, we employed experimental results for bimodal slurry composed of coarse granite rock (the stratified fraction) and fine sand (the pseudo-homogeneous fraction) to analyze the observed considerable reduction of the frictional head loss caused by an addition of the fine sand to the granite rock slurry. In this work, we extend our analysis to the other bimodal slurries composed of permutations of the four fractions (in total 3 additional bimodal slurries) with a major objective to identify possible mechanisms leading to a modification of the frictional head loss due to an addition of a finer fraction to a coarser mono-disperse slurry, and to quantify this effect for the purposes of a predictive four-component model (4CM). The investigation shows that the frictional loss of bimodal slurry is always smaller than the theoretical loss obtained as the sum of losses of the fractions, although the massive reduction observed in the slurry composed of the stratified rock and fine sand is not observed in any other bimodal slurry. The investigation also suggests that the friction effect obtained by the finer fraction addition is due to different mechanisms for different bimodal slurries although all mechanisms are associated with altering mechanical friction due to granular contacts. It is shown that the observed effects can be well reproduced by the friction loss model 4CM, calibrated by the experimental data set from the 203-mm pipe and validated by the data set from the 103-mm pipe.
{"title":"Frictional Head Loss of Various Bimodal Settling Slurry Flows in Pipe","authors":"V. Matoušek, R. Visintainer, J. Furlan, A. Sellgren","doi":"10.1115/ajkfluids2019-5395","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5395","url":null,"abstract":"\u0000 Pipe flows of bimodal settling slurries exhibit frictional head losses quite different from those determined simply as a sum of loss contributions by the individual fractions. Mechanisms governing flow friction and resulting from an interaction of grains of different fractions in transported slurry are not well understood. This makes a prediction of the frictional head loss in flows of bimodal slurries with Newtonian carrier uncertain. An extensive experimental campaign was conducted in GIW Hydraulic Laboratory in 2016 with slurries of four narrow graded fractions of the virtually same grain densities and very different grain sizes (carrier-liquid fraction, pseudo-homogeneous-, heterogeneous-, and stratified fractions). Besides testing of the individual fractions, different combinations of the fraction mixtures (bimodal, three- and four-component) were tested as well.\u0000 In our previous work published in 2018, we employed experimental results for bimodal slurry composed of coarse granite rock (the stratified fraction) and fine sand (the pseudo-homogeneous fraction) to analyze the observed considerable reduction of the frictional head loss caused by an addition of the fine sand to the granite rock slurry.\u0000 In this work, we extend our analysis to the other bimodal slurries composed of permutations of the four fractions (in total 3 additional bimodal slurries) with a major objective to identify possible mechanisms leading to a modification of the frictional head loss due to an addition of a finer fraction to a coarser mono-disperse slurry, and to quantify this effect for the purposes of a predictive four-component model (4CM). The investigation shows that the frictional loss of bimodal slurry is always smaller than the theoretical loss obtained as the sum of losses of the fractions, although the massive reduction observed in the slurry composed of the stratified rock and fine sand is not observed in any other bimodal slurry. The investigation also suggests that the friction effect obtained by the finer fraction addition is due to different mechanisms for different bimodal slurries although all mechanisms are associated with altering mechanical friction due to granular contacts.\u0000 It is shown that the observed effects can be well reproduced by the friction loss model 4CM, calibrated by the experimental data set from the 203-mm pipe and validated by the data set from the 103-mm pipe.","PeriodicalId":322380,"journal":{"name":"Volume 5: Multiphase Flow","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124135573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-28DOI: 10.1115/ajkfluids2019-4614
A. Kendoush
Void fraction measuring techniques are reviewed with emphasis on applications to multiphase flow. The presentation is divided into two main sections; intrusive where the probe penetrates into the flow field, and non-intrusive where the detection is done remotely. The latter is more preferrable than the former. We subdivided the non-intrusive techniques into into two main categories; nuclear and non-nuclear. In the nuclear section, we discussed the utilization of almost all types of radiations, namely; beta, neutrons, gamma, X-ray, near infrared, in addition to the nuclear magnetic resonance. In the non-nuclear techniques, we presented the following methods; fluorescence, optical sensors, laser, autotransformer winding, ultrasonic, and photgraphy. Some other non nuclear miscellaneous techniques were discussed.
{"title":"The Science and Technology of Void Fraction Measurements in Multiphase Flow","authors":"A. Kendoush","doi":"10.1115/ajkfluids2019-4614","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4614","url":null,"abstract":"\u0000 Void fraction measuring techniques are reviewed with emphasis on applications to multiphase flow. The presentation is divided into two main sections; intrusive where the probe penetrates into the flow field, and non-intrusive where the detection is done remotely. The latter is more preferrable than the former. We subdivided the non-intrusive techniques into into two main categories; nuclear and non-nuclear. In the nuclear section, we discussed the utilization of almost all types of radiations, namely; beta, neutrons, gamma, X-ray, near infrared, in addition to the nuclear magnetic resonance. In the non-nuclear techniques, we presented the following methods; fluorescence, optical sensors, laser, autotransformer winding, ultrasonic, and photgraphy. Some other non nuclear miscellaneous techniques were discussed.","PeriodicalId":322380,"journal":{"name":"Volume 5: Multiphase Flow","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133227206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-28DOI: 10.1115/ajkfluids2019-5537
Nafiseh Banazadeh-Neishabouri, S. Shirazi
Effects of particle velocity, impact angle and particle size and shape on erosive behavior of Fiberglass Reinforced Plastic (FRP) and Polyethylene were investigated. Experiments were carried out with two particle velocities (18 and 32 m/s) and different impact angles ranging from 15 to 90 degrees. Silica sands with sizes of 75, 150 and 300 μm was utilized as erodent to study effects of sand shape and size. Results revealed erosion data of FRP and Polyethylene are similar to ductile materials as they display maximum erosion ratio at 30 degrees impact angle. However, Polyethylene showed an interesting behavior at 75 and 90 degrees; sand particles were embedded into the specimen and mass gain of specimen has been observed. 3D scan of wear patterns of specimens was obtained by 3D profilometer in order to evaluate the erosion depth and wear pattern of the surface.
{"title":"Erosive Wear Behavior of Fiberglass Reinforced Plastic Composite and Polyethylene","authors":"Nafiseh Banazadeh-Neishabouri, S. Shirazi","doi":"10.1115/ajkfluids2019-5537","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5537","url":null,"abstract":"\u0000 Effects of particle velocity, impact angle and particle size and shape on erosive behavior of Fiberglass Reinforced Plastic (FRP) and Polyethylene were investigated. Experiments were carried out with two particle velocities (18 and 32 m/s) and different impact angles ranging from 15 to 90 degrees. Silica sands with sizes of 75, 150 and 300 μm was utilized as erodent to study effects of sand shape and size. Results revealed erosion data of FRP and Polyethylene are similar to ductile materials as they display maximum erosion ratio at 30 degrees impact angle. However, Polyethylene showed an interesting behavior at 75 and 90 degrees; sand particles were embedded into the specimen and mass gain of specimen has been observed. 3D scan of wear patterns of specimens was obtained by 3D profilometer in order to evaluate the erosion depth and wear pattern of the surface.","PeriodicalId":322380,"journal":{"name":"Volume 5: Multiphase Flow","volume":"127 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121533266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-28DOI: 10.1115/ajkfluids2019-4966
Morteza Kiasadegh, Z. Dehghani, A. Naseri, O. Abouali, G. Ahmadi
Steady airflow pattern during a full breathing cycle in human upper and central respiratory tract was simulated by solving the Navier-Stokes and continuity equations. For ellipsoidal fiber trajectory analysis under cyclic breathing condition, several user defined functions (UDFs) were developed and coupled to the ANSYS-Fluent discrete phase model (DPM). The developed model accounted for solving the coupled translational and rotational equations of motion of ellipsoidal fibers. The airway passage model was extended from the vestibule to the fifth generation of the bronchial bifurcations obtained mostly from computed tomography (CT) scan. A constant flow rate of 15 L/min was used to simulate the normal breathing condition. The velocity and pressure fields for different regions of the respiratory track were evaluated and used for Lagrangian particle trajectory analysis. Total and regional depositions of each region for a range of ellipsoidal particle diameter and aspect ratios were evaluated and the results compared with the experimental data.
{"title":"Numerical Simulation of Airflow and Ellipsoidal Particle Deposition in Human Upper and Central Respiratory Tract","authors":"Morteza Kiasadegh, Z. Dehghani, A. Naseri, O. Abouali, G. Ahmadi","doi":"10.1115/ajkfluids2019-4966","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4966","url":null,"abstract":"\u0000 Steady airflow pattern during a full breathing cycle in human upper and central respiratory tract was simulated by solving the Navier-Stokes and continuity equations. For ellipsoidal fiber trajectory analysis under cyclic breathing condition, several user defined functions (UDFs) were developed and coupled to the ANSYS-Fluent discrete phase model (DPM). The developed model accounted for solving the coupled translational and rotational equations of motion of ellipsoidal fibers. The airway passage model was extended from the vestibule to the fifth generation of the bronchial bifurcations obtained mostly from computed tomography (CT) scan. A constant flow rate of 15 L/min was used to simulate the normal breathing condition. The velocity and pressure fields for different regions of the respiratory track were evaluated and used for Lagrangian particle trajectory analysis. Total and regional depositions of each region for a range of ellipsoidal particle diameter and aspect ratios were evaluated and the results compared with the experimental data.","PeriodicalId":322380,"journal":{"name":"Volume 5: Multiphase Flow","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128117992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-28DOI: 10.1115/ajkfluids2019-4622
Xianfang Wu, Tian Xiao, M. Tan, Hou-lin Liu
As a typical fluid mechanics problem, pump blockage has always been a hot research topic. The obtaining of the distribution of coarse particles in the solid-liquid two-phase flow pump is the basis of improving its non-blocking performance. High-speed photography technique is applied to do visualizing test and research on the distribution of coarse particles in a double blade pump. The effects of particle concentration, particle density and particle diameter on the distribution of coarse particles in the solid-liquid two-phase flow pump at different phases are studied. Besides, the variation of hydraulic performance of the double blade pump under different parameters is also analyzed. The results show that the particles in the impeller mainly located in the vicinity of the blade pressure surface, and the distribution of the particles in each section of the volute is quite different. The great difference in particle density can result in obviously uneven distribution of particles. With the increase of particle diameter, particle density and particle concentration, the pump head and efficiency both decrease while the shaft power increase on the contrary. This research results can also provide a basis for the optimization design of solid-liquid two-phase flow pumps.
{"title":"Visualizing Test on the Distribution Rule of Coarse Particles in a Double Blade Pump","authors":"Xianfang Wu, Tian Xiao, M. Tan, Hou-lin Liu","doi":"10.1115/ajkfluids2019-4622","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4622","url":null,"abstract":"\u0000 As a typical fluid mechanics problem, pump blockage has always been a hot research topic. The obtaining of the distribution of coarse particles in the solid-liquid two-phase flow pump is the basis of improving its non-blocking performance. High-speed photography technique is applied to do visualizing test and research on the distribution of coarse particles in a double blade pump. The effects of particle concentration, particle density and particle diameter on the distribution of coarse particles in the solid-liquid two-phase flow pump at different phases are studied. Besides, the variation of hydraulic performance of the double blade pump under different parameters is also analyzed. The results show that the particles in the impeller mainly located in the vicinity of the blade pressure surface, and the distribution of the particles in each section of the volute is quite different. The great difference in particle density can result in obviously uneven distribution of particles. With the increase of particle diameter, particle density and particle concentration, the pump head and efficiency both decrease while the shaft power increase on the contrary. This research results can also provide a basis for the optimization design of solid-liquid two-phase flow pumps.","PeriodicalId":322380,"journal":{"name":"Volume 5: Multiphase Flow","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115370148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-28DOI: 10.1115/ajkfluids2019-4781
Guangjian Zhang, I. Khlifa, O. Coutier-Delgosha
The cavitating flows created in a small Venturi tube with throat cross section 4 × 15.34 mm2 are investigated based on ultra-fast x-ray imaging. The instantaneous velocities of the liquid and vapor are measured simultaneously by tracking seeding particles and vapor structures respectively while the vapor volume fraction is derived from the different x-ray attenuation. Wavelet decomposition with appropriate thresholds is used to separate seeding particles from vapor structures, so that image cross-correlations could be applied on the two phases separately. This study presents data on mean velocity and void ratio field, statistical turbulent quantities in three different cavitation levels with the same reference velocity. A type of cavitation associated with a weak but persistent re-entrant jet is described. The comparison between the cavitation and the noncavitating flow shows that the averaged flow field is significantly altered by the presence of cavitation and the vapor formation near the throat area is observed to suppress velocity fluctuations.
{"title":"Experimental Investigation of Turbulent Cavitating Flows in a Small Venturi Nozzle","authors":"Guangjian Zhang, I. Khlifa, O. Coutier-Delgosha","doi":"10.1115/ajkfluids2019-4781","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4781","url":null,"abstract":"\u0000 The cavitating flows created in a small Venturi tube with throat cross section 4 × 15.34 mm2 are investigated based on ultra-fast x-ray imaging. The instantaneous velocities of the liquid and vapor are measured simultaneously by tracking seeding particles and vapor structures respectively while the vapor volume fraction is derived from the different x-ray attenuation. Wavelet decomposition with appropriate thresholds is used to separate seeding particles from vapor structures, so that image cross-correlations could be applied on the two phases separately. This study presents data on mean velocity and void ratio field, statistical turbulent quantities in three different cavitation levels with the same reference velocity. A type of cavitation associated with a weak but persistent re-entrant jet is described. The comparison between the cavitation and the noncavitating flow shows that the averaged flow field is significantly altered by the presence of cavitation and the vapor formation near the throat area is observed to suppress velocity fluctuations.","PeriodicalId":322380,"journal":{"name":"Volume 5: Multiphase Flow","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114270488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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