Rodolfo Marcilli Perissinotto, William Denner Pires Fonseca, Rafael Franklin Lazaro Cerqueira, William Monte Verde, Antonio C. Bannwart, Erick Franklin, Marcelo Souza Castro
Abstract For almost a century, humans have relied on pumps for the transport of low-viscous fluids in commercial, agricultural, industrial activities. Details of the fluid flow in impellers often influence the overall performance of the pump, and may explain unstable and inefficient operations taking place sometimes. However, most studies in the literature were devoted to understanding the flow in the mid-axial position of the impeller, only a few focusing their analysis on regions closer to solid walls. This paper aims at studying the water flow on the vicinity of the front and rear covers (shroud and hub) of a radial impeller to address the influence of these walls on the fluid dynamics. For that, experiments using particle image velocimetry (PIV) were conducted in a transparent pump at three different axial planes, and the PIV images were processed for obtaining the average velocity fields and profiles, and turbulence levels. Our results suggest that: significant angular deviations are observed when the velocity vectors on peripheral planes are compared with those on the central plane; the velocity profiles close to the border are similar to those in the middle, but the magnitudes are lower close to the hub than to the shroud; the turbulent kinetic energy on the periphery is eight times greater than that measured at the center. Our results bring new insights that can help proposing mathematical models and improving the design of new impellers. A database and technical drawings of the centrifugal pump are also available in this paper.
{"title":"Particle Image Velocimetry In A Centrifugal Pump: Influence Of Walls On The Flow At Different Axial Positions","authors":"Rodolfo Marcilli Perissinotto, William Denner Pires Fonseca, Rafael Franklin Lazaro Cerqueira, William Monte Verde, Antonio C. Bannwart, Erick Franklin, Marcelo Souza Castro","doi":"10.1115/1.4063616","DOIUrl":"https://doi.org/10.1115/1.4063616","url":null,"abstract":"Abstract For almost a century, humans have relied on pumps for the transport of low-viscous fluids in commercial, agricultural, industrial activities. Details of the fluid flow in impellers often influence the overall performance of the pump, and may explain unstable and inefficient operations taking place sometimes. However, most studies in the literature were devoted to understanding the flow in the mid-axial position of the impeller, only a few focusing their analysis on regions closer to solid walls. This paper aims at studying the water flow on the vicinity of the front and rear covers (shroud and hub) of a radial impeller to address the influence of these walls on the fluid dynamics. For that, experiments using particle image velocimetry (PIV) were conducted in a transparent pump at three different axial planes, and the PIV images were processed for obtaining the average velocity fields and profiles, and turbulence levels. Our results suggest that: significant angular deviations are observed when the velocity vectors on peripheral planes are compared with those on the central plane; the velocity profiles close to the border are similar to those in the middle, but the magnitudes are lower close to the hub than to the shroud; the turbulent kinetic energy on the periphery is eight times greater than that measured at the center. Our results bring new insights that can help proposing mathematical models and improving the design of new impellers. A database and technical drawings of the centrifugal pump are also available in this paper.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136117641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This study was aimed at numerically investigating the source, generation mechanism, and strategy for reducing aerodynamic noises inside a steam turbine control valve. A delayed detached eddy simulation was performed to extract the three-dimensional unsteady turbulent flow structures formed within the serpentine flow passage of the turbine valve. Acoustic analogies, spatial Fourier transform, and spectral proper orthogonal decomposition on the delayed detached eddy simulation-simulated flow data were complementarily combined to clarify the generation mechanism of tonal and broadband aerodynamic noises. The results showed that broadband noises were produced by wall-attached jet flow and turbulent mixing flow between the annular wall jets and central reverse flow. High-intensity tonal noises were generated by the excitation of multi-order natural acoustic modes of the bell-shaped valve spindle. The intensive acoustic pressure pulsations concentrated inside the bell jar and propagated along the diffuser to the downstream turbine chamber. A novel ring acoustic liner was designed using the acoustic impedance model to reduce the valve noises without sacrificing the flow performance. The noise reduction effectiveness was evaluated by solving the linearized Navier–Stokes equations in the frequency domain.
{"title":"A Combined Delayed Detached Eddy Simulation and Linearized Navier–Stokes Equation Study on the Generation and Reduction of Aerodynamic Noises Inside Steam Turbine Control Valve With Acoustic Liner","authors":"Yuchao Tang, Peng Wang, Yingzheng Liu","doi":"10.1115/1.4063020","DOIUrl":"https://doi.org/10.1115/1.4063020","url":null,"abstract":"Abstract This study was aimed at numerically investigating the source, generation mechanism, and strategy for reducing aerodynamic noises inside a steam turbine control valve. A delayed detached eddy simulation was performed to extract the three-dimensional unsteady turbulent flow structures formed within the serpentine flow passage of the turbine valve. Acoustic analogies, spatial Fourier transform, and spectral proper orthogonal decomposition on the delayed detached eddy simulation-simulated flow data were complementarily combined to clarify the generation mechanism of tonal and broadband aerodynamic noises. The results showed that broadband noises were produced by wall-attached jet flow and turbulent mixing flow between the annular wall jets and central reverse flow. High-intensity tonal noises were generated by the excitation of multi-order natural acoustic modes of the bell-shaped valve spindle. The intensive acoustic pressure pulsations concentrated inside the bell jar and propagated along the diffuser to the downstream turbine chamber. A novel ring acoustic liner was designed using the acoustic impedance model to reduce the valve noises without sacrificing the flow performance. The noise reduction effectiveness was evaluated by solving the linearized Navier–Stokes equations in the frequency domain.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135060305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yandong Gu, Sun Hao, Chuan Wang, Rong Lu, Benqing Liu, Ge Jie
Abstract Multi-stage centrifugal pumps are frequently used in high-lift applications and consume considerable energy, but suffer from poor performance and large axial force. The rear shroud of impeller is trimmed for reducing axial thrust, but this degrades performance. This study analyses performance degradation and optimizes performance and axial force. Experiments and simulations are conducted on different ratios of rear shroud to front shroud (Lambda). Total pressure losses are calculated, and flow losses are visualized using the entropy generation method. Both measured and simulated performances decrease as the rear shroud is trimmed. Designs with different Lambda meet the head coefficient requirement of 1.1. However, Lambda of 0.86 has the best efficiency of 42.7%, Lambda of 0.83 reaches 42.5%, Lambda of 0.8 shows the lowest efficiency of 39.9%. Efficiency in the middle channel improves as the rear shroud is trimmed, but this cannot offset increased losses in the impeller and rear side chamber. Entropy production is exacerbated in the axial passage between impeller and rear side chamber due to the collision between impeller-driven flow and pressure-driven backflow. When Lambda is reduced by 0.03, axial thrust drops by 7%. To compromise between performance and axial thrust, Lambda should be designed at 0.83.
{"title":"Effect of Trimmed Rear Shroud On Performance and Axial Thrust of Multi-Stage Centrifugal Pump with Emphasis On Visualizing Flow Losses","authors":"Yandong Gu, Sun Hao, Chuan Wang, Rong Lu, Benqing Liu, Ge Jie","doi":"10.1115/1.4063438","DOIUrl":"https://doi.org/10.1115/1.4063438","url":null,"abstract":"Abstract Multi-stage centrifugal pumps are frequently used in high-lift applications and consume considerable energy, but suffer from poor performance and large axial force. The rear shroud of impeller is trimmed for reducing axial thrust, but this degrades performance. This study analyses performance degradation and optimizes performance and axial force. Experiments and simulations are conducted on different ratios of rear shroud to front shroud (Lambda). Total pressure losses are calculated, and flow losses are visualized using the entropy generation method. Both measured and simulated performances decrease as the rear shroud is trimmed. Designs with different Lambda meet the head coefficient requirement of 1.1. However, Lambda of 0.86 has the best efficiency of 42.7%, Lambda of 0.83 reaches 42.5%, Lambda of 0.8 shows the lowest efficiency of 39.9%. Efficiency in the middle channel improves as the rear shroud is trimmed, but this cannot offset increased losses in the impeller and rear side chamber. Entropy production is exacerbated in the axial passage between impeller and rear side chamber due to the collision between impeller-driven flow and pressure-driven backflow. When Lambda is reduced by 0.03, axial thrust drops by 7%. To compromise between performance and axial thrust, Lambda should be designed at 0.83.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":"167 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135308011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Our response to the Discussion by Pantokratoras [1] is as follows:Claim-1: The author [1] claimed that the temperature profiles did not converge smoothly. It does not mean that the results are wrong. All the obtained outcomes satisfied the boundary conditions of the current study. This happened due to the common eta values considered for both flow and thermal profiles. We can change the eta value for smooth convergence of thermal profiles but there will not be any change in results. Many theoretical investigations published similar types of outcomes in this area of research. We already provided the comparative analysis to show that the obtained results are correct and agree well with the available results in the literature.Claim-2: It is clear that gravity acts in the vertical direction, and the effect is more on vertical flows. It does not mean that there is no effect of gravity on the horizontal flow. The impact of buoyancy also impacts the flow amplitude irrespective of its flow direction.The Refs. [2–10] support our claims.Finally, the claims made by the author Asterios Pantokratoras are not acceptable for the current theoretical work.
{"title":"Closure to Discussion of “Higher Order Chemical Reaction and Radiation Effects on Magnetohydrodynamic Flow of a Maxwell Nanofluid With Cattaneo-Christov Heat Flux Model Over a Stretching Sheet in a Porous Medium” (Vinodkumar Reddy, M. and Lakshminarayana, P., 2022, ASME J. Fluids Eng., 144(4), p. 041204)","authors":"Vinodkumar Reddy Mulinti, P Lakshminarayana","doi":"10.1115/1.4063077","DOIUrl":"https://doi.org/10.1115/1.4063077","url":null,"abstract":"Our response to the Discussion by Pantokratoras [1] is as follows:Claim-1: The author [1] claimed that the temperature profiles did not converge smoothly. It does not mean that the results are wrong. All the obtained outcomes satisfied the boundary conditions of the current study. This happened due to the common eta values considered for both flow and thermal profiles. We can change the eta value for smooth convergence of thermal profiles but there will not be any change in results. Many theoretical investigations published similar types of outcomes in this area of research. We already provided the comparative analysis to show that the obtained results are correct and agree well with the available results in the literature.Claim-2: It is clear that gravity acts in the vertical direction, and the effect is more on vertical flows. It does not mean that there is no effect of gravity on the horizontal flow. The impact of buoyancy also impacts the flow amplitude irrespective of its flow direction.The Refs. [2–10] support our claims.Finally, the claims made by the author Asterios Pantokratoras are not acceptable for the current theoretical work.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136215058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The most important development in Fluid Mechanics during the 20th century was the concept of boundary layer flow introduced by Prandtl in Ref. [1]. A boundary layer is that layer of fluid which forms in the vicinity of a surface bounding the fluid. Every time a fluid moves along a surface a boundary layer near the surface appears. Therefore, boundary layers exist in the interior of water pipes, in sewer pipes, in irrigation channels, near the earth's surface, and around buildings due to winds, near airplane wings, around a moving car, at the river bottom, inside the blood vessels and so on. Therefore, it is a popular field in Fluid Mechanics for engineers, physicists, and mathematicians. Hundreds of papers are published each year in this field. However, errors appear in many papers. Four usual errors made in investigation of boundary layer flows have been analyzed by Pantokratoras in Ref. [2]. The most usual error is that concerning the truncation of velocity and temperature profiles, and this kind of errors exist in Ref. [3]. The analysis of errors in Ref. [3] follows.In Ref. [3] the boundary conditions (11) are as follows: (1)f′=0,θ=0,ϕ=0 asη→∞where f′ is the nondimensional fluid velocity, θ is the nondimensional temperature, and ϕ is the nondimensional concentration. In Eq. (1), η→∞ means a very long η.In Fig. 1 of the present work, the dimensionless temperature profile taken from Fig. 11 of Ref. [3] is shown. It is seen that the temperature profile from Ref. [3] does not approach the ambient condition asymptotically but intersects the horizontal axis with a steep angle (the profile by Ref. [3] is a straight line). At the same figure, it is shown a correct profile (sketch), proposed by the present author, which extends to high values of transverse component η and approaches smoothly the ambient condition. In Fig. 11 of Ref. [3], the calculations have been restricted to a maximum η equal to 5. It is obvious that this calculation domain is insufficient to capture the real shape of profile and a higher value of η is needed.According to above analysis, most of the curves in Figs. 3, 5, 6, 8–16, 18–21 in Ref. [3] are incorrect.The temperature gradient θ′(0)=∂θ(0)∂η at point A, which lies at the sheet, is quite different in the work presented in Ref. [3] and the corrected profile. This means that ALL −θ′(0) values in Tables 1–4 in Ref. [3] are wrong. More information on the truncation error is given by Pantokratoras in Ref. [4]. Recently a similar paper with truncated profiles has been retracted [5].From Fig. 1 of Ref. [3], it is clear that the x axis is horizontal, and the y axis is vertical. The horizontal momentum equation (2) in Ref. [3] is as follows: (2)u∂u∂x+v∂u∂y=υ∂2u∂y2−λ1(u2∂2u∂x2+2uv∂2u∂x∂y+v2∂2u∂y2)−υku−σB02uρ+g(βT(T−T∞)+βC(C−C∞)It is well known that gravity acts in the vertical direction. Therefore, the gravity term g(βT(T−T∞)+βC(C−C∞) in Eq. (2) must be zero. For the same reason, the gravity terms Grθ and Gcϕ in the transformed equatio
{"title":"Discussion on “Higher Order Chemical Reaction and Radiation Effects on Magnetohydrodynamic Flow of a Maxwell Nanofluid With Cattaneo–Christov Heat Flux Model Over a Stretching Sheet in a Porous Medium” (Reddy Vinodkumar, M. and Lakshminarayana, P., 2022, ASME J. Fluids Eng., 144(4), p. 041204)","authors":"Asterios Pantokratoras","doi":"10.1115/1.4063076","DOIUrl":"https://doi.org/10.1115/1.4063076","url":null,"abstract":"The most important development in Fluid Mechanics during the 20th century was the concept of boundary layer flow introduced by Prandtl in Ref. [1]. A boundary layer is that layer of fluid which forms in the vicinity of a surface bounding the fluid. Every time a fluid moves along a surface a boundary layer near the surface appears. Therefore, boundary layers exist in the interior of water pipes, in sewer pipes, in irrigation channels, near the earth's surface, and around buildings due to winds, near airplane wings, around a moving car, at the river bottom, inside the blood vessels and so on. Therefore, it is a popular field in Fluid Mechanics for engineers, physicists, and mathematicians. Hundreds of papers are published each year in this field. However, errors appear in many papers. Four usual errors made in investigation of boundary layer flows have been analyzed by Pantokratoras in Ref. [2]. The most usual error is that concerning the truncation of velocity and temperature profiles, and this kind of errors exist in Ref. [3]. The analysis of errors in Ref. [3] follows.In Ref. [3] the boundary conditions (11) are as follows: (1)f′=0,θ=0,ϕ=0 asη→∞where f′ is the nondimensional fluid velocity, θ is the nondimensional temperature, and ϕ is the nondimensional concentration. In Eq. (1), η→∞ means a very long η.In Fig. 1 of the present work, the dimensionless temperature profile taken from Fig. 11 of Ref. [3] is shown. It is seen that the temperature profile from Ref. [3] does not approach the ambient condition asymptotically but intersects the horizontal axis with a steep angle (the profile by Ref. [3] is a straight line). At the same figure, it is shown a correct profile (sketch), proposed by the present author, which extends to high values of transverse component η and approaches smoothly the ambient condition. In Fig. 11 of Ref. [3], the calculations have been restricted to a maximum η equal to 5. It is obvious that this calculation domain is insufficient to capture the real shape of profile and a higher value of η is needed.According to above analysis, most of the curves in Figs. 3, 5, 6, 8–16, 18–21 in Ref. [3] are incorrect.The temperature gradient θ′(0)=∂θ(0)∂η at point A, which lies at the sheet, is quite different in the work presented in Ref. [3] and the corrected profile. This means that ALL −θ′(0) values in Tables 1–4 in Ref. [3] are wrong. More information on the truncation error is given by Pantokratoras in Ref. [4]. Recently a similar paper with truncated profiles has been retracted [5].From Fig. 1 of Ref. [3], it is clear that the x axis is horizontal, and the y axis is vertical. The horizontal momentum equation (2) in Ref. [3] is as follows: (2)u∂u∂x+v∂u∂y=υ∂2u∂y2−λ1(u2∂2u∂x2+2uv∂2u∂x∂y+v2∂2u∂y2)−υku−σB02uρ+g(βT(T−T∞)+βC(C−C∞)It is well known that gravity acts in the vertical direction. Therefore, the gravity term g(βT(T−T∞)+βC(C−C∞) in Eq. (2) must be zero. For the same reason, the gravity terms Grθ and Gcϕ in the transformed equatio","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136215059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thomas Shepard, Deify Law, Jacob Dahl, Rhett Reichstadt, Arun Sriniwas Selvamani
Abstract When examining the literature for flow effects on circular cylinders one can find many studies on infinite cylinders and cantilevered cylinders but minimal data related to cylinders with two free ends (Shepard, T., Law, D., Dahl, J., Reichstadt, R., and Selvamani, A. S., 2022, “Impact of Aspect Ratio on Drag and Flow Structure for Cylinders With Two Free Ends,” ASME Paper No. V001T03A031.). The limited data available shows that the cylinder aspect ratio affects the drag and frequency content of flow within the wake however these studies were done at discreet Reynolds numbers. In order to better understand the combined impact of aspect ratio and Reynolds number a series of wind tunnel tests and numerical simulations has been conducted for cylinders with two free ends having aspect ratios of 2–15. Tests were carried out in the subcritical regime with Reynolds numbers ranging 13000–105,000. Tip vortex effects, which vary with aspect ratio, are shown to impact the cylinder surface pressure, drag coefficient, and wake Strouhal numbers though Reynolds number effects are minor for the conditions studied. The results are compared against existing historical data and show the trend of drag coefficient increasing with cylinder aspect ratio (Shepard, T., Law, D., Dahl, J., Reichstadt, R., and Selvamani, A. S., 2022, “Impact of Aspect Ratio on Drag and Flow Structure for Cylinders With Two Free Ends,” ASME Paper No. V001T03A031).
当检查关于圆柱流动影响的文献时，人们可以发现许多关于无限圆柱体和悬臂圆柱体的研究，但与两个自由端圆柱体相关的数据很少(Shepard, T.， Law, D.， Dahl, J.， Reichstadt, R.和Selvamani, A. S.， 2022，“长径比对两个自由端圆柱体阻力和流动结构的影响”，ASME论文号:V001T03A031)。有限的可用数据表明，圆柱展弦比影响尾迹内流动的阻力和频率含量，但这些研究是在离散雷诺数下进行的。为了更好地了解展弦比和雷诺数的综合影响，对两个自由端展弦比为2-15的圆柱体进行了一系列风洞试验和数值模拟。试验在亚临界状态下进行，雷诺数范围为13000 - 105000。叶尖涡效应随展弦比的变化而变化，虽然在研究条件下雷诺数效应较小，但叶尖涡效应对气缸表面压力、阻力系数和尾流斯特罗哈尔数有影响。结果与现有的历史数据进行了比较，显示了阻力系数随气缸长径比增加的趋势(Shepard, T.， Law, D.， Dahl, J.， Reichstadt, R.， and Selvamani, A. S.， 2022，“长径比对两个自由端气缸阻力和流动结构的影响”，ASME论文编号:V001T03A031)。
{"title":"Impact of Aspect Ratio on Drag and Flow Structure for Cylinders With Two Free Ends","authors":"Thomas Shepard, Deify Law, Jacob Dahl, Rhett Reichstadt, Arun Sriniwas Selvamani","doi":"10.1115/1.4062575","DOIUrl":"https://doi.org/10.1115/1.4062575","url":null,"abstract":"Abstract When examining the literature for flow effects on circular cylinders one can find many studies on infinite cylinders and cantilevered cylinders but minimal data related to cylinders with two free ends (Shepard, T., Law, D., Dahl, J., Reichstadt, R., and Selvamani, A. S., 2022, “Impact of Aspect Ratio on Drag and Flow Structure for Cylinders With Two Free Ends,” ASME Paper No. V001T03A031.). The limited data available shows that the cylinder aspect ratio affects the drag and frequency content of flow within the wake however these studies were done at discreet Reynolds numbers. In order to better understand the combined impact of aspect ratio and Reynolds number a series of wind tunnel tests and numerical simulations has been conducted for cylinders with two free ends having aspect ratios of 2–15. Tests were carried out in the subcritical regime with Reynolds numbers ranging 13000–105,000. Tip vortex effects, which vary with aspect ratio, are shown to impact the cylinder surface pressure, drag coefficient, and wake Strouhal numbers though Reynolds number effects are minor for the conditions studied. The results are compared against existing historical data and show the trend of drag coefficient increasing with cylinder aspect ratio (Shepard, T., Law, D., Dahl, J., Reichstadt, R., and Selvamani, A. S., 2022, “Impact of Aspect Ratio on Drag and Flow Structure for Cylinders With Two Free Ends,” ASME Paper No. V001T03A031).","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135493643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kamil Urbanowicz, Haixiao Jing, Anton Bergant, Michal Stosiak, Marek Lubecki
Abstract Analytical formulas for laminar water hammer in horizontal pipes were extended and simplified into a compact mathematical form based on dimensionless parameters: dimensionless time, water hammer number, etc. Detailed treatment of turbulent water hammer analytical solutions is beyond the scope of this paper. In the Muto and Takahashi solution, novel Laplace and time domain formulas for flow velocity and wall shear stress were developed. A series of comparative studies of unified analytical solutions with numerical solutions and the results of measurements were carried out. The study shows that models that account for the frequency-dependent nature of hydraulic resistance agree very well with experimental results over a wide range of water hammer numbers Wh, particularly when Wh ≤ 0.1.
{"title":"Progress in Analytical Modeling of Water Hammer","authors":"Kamil Urbanowicz, Haixiao Jing, Anton Bergant, Michal Stosiak, Marek Lubecki","doi":"10.1115/1.4062290","DOIUrl":"https://doi.org/10.1115/1.4062290","url":null,"abstract":"Abstract Analytical formulas for laminar water hammer in horizontal pipes were extended and simplified into a compact mathematical form based on dimensionless parameters: dimensionless time, water hammer number, etc. Detailed treatment of turbulent water hammer analytical solutions is beyond the scope of this paper. In the Muto and Takahashi solution, novel Laplace and time domain formulas for flow velocity and wall shear stress were developed. A series of comparative studies of unified analytical solutions with numerical solutions and the results of measurements were carried out. The study shows that models that account for the frequency-dependent nature of hydraulic resistance agree very well with experimental results over a wide range of water hammer numbers Wh, particularly when Wh ≤ 0.1.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136267128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract An investigation of flow acceleration from initial statistically steady turbulent flow to final statistically steady turbulent flow is conducted experimentally using particle image velocimetry (PIV) and constant temperature anemometry (CTA). The turbulence response is investigated as the acceleration periods and acceleration rates are varied in a controlled fashion. This work expands the research by Mathur et al. (2018, “Temporal Acceleration of a Turbulent Channel Flow,” J. Fluid Mech., 835, pp. 471–490.) studying slower and longer transient flows. It also complements the numerical studies of a step increase in the flowrate of (He and Seddighi, 2013, “Turbulence in Transient Channel Flow,” J. Fluid Mech., 715, pp. 60–102. and He and Seddighi, 2015, “Transition of Transient Channel Flow After a Change in Reynolds Number,” J. Fluid Mech., 764, pp. 395–427.). The results obtained from the current investigations are qualitatively similar to those obtained previously. Consistent with previous studies, the response of turbulence in the current slow transient flow is again characterized by a laminar-turbulent transition. The initial increase of the flow development among the cases investigated can be categorized as faster, medium, and slower responses. Modifications are made to the equivalent Reynolds number and the initial turbulence intensity proposed earlier in order to account for the slow accelerating flow rates and the continuous change of the bulk velocities of the cases investigated. It has been shown that the critical equivalent Reynolds number based on these modifications and the initial turbulence intensity are well correlated for all cases investigated and a power-law relation is established.
摘要采用粒子图像测速(PIV)和恒温测速(CTA)对初始统计稳定湍流到最终统计稳定湍流的加速度进行了实验研究。研究了当加速度周期和加速度速率以受控方式变化时的湍流响应。这项工作扩展了Mathur等人(2018)的研究，“湍流通道流动的时间加速度”，J.流体力学。， 835页，471-490页)，研究较慢和较长的瞬态流动。这也补充了(He和Seddighi, 2013，“湍流在瞬态通道流动”，J.流体力学。， 715页，60-102页。and He and Seddighi, 2015，“雷诺数变化后瞬态通道流动的过渡”，流体力学。第764页，395-427页)。从目前的调查中获得的结果在质量上与以前获得的结果相似。与以往的研究一致，当前缓慢瞬态流动中的湍流响应再次以层流-湍流过渡为特征。在所调查的病例中，流动发展的初始增加可分为快速、中等和较慢的响应。为了考虑所研究的情况下的缓慢加速流速和体速度的连续变化，对先前提出的等效雷诺数和初始湍流强度进行了修改。结果表明，在所研究的所有情况下，基于这些修正的临界等效雷诺数与初始湍流强度具有良好的相关性，并建立了幂律关系。
{"title":"Experimental Study of Turbulence Response in a Slowly Accelerating Turbulent Channel Flow","authors":"Benjamin Oluwadare, Shuisheng He","doi":"10.1115/1.4062166","DOIUrl":"https://doi.org/10.1115/1.4062166","url":null,"abstract":"Abstract An investigation of flow acceleration from initial statistically steady turbulent flow to final statistically steady turbulent flow is conducted experimentally using particle image velocimetry (PIV) and constant temperature anemometry (CTA). The turbulence response is investigated as the acceleration periods and acceleration rates are varied in a controlled fashion. This work expands the research by Mathur et al. (2018, “Temporal Acceleration of a Turbulent Channel Flow,” J. Fluid Mech., 835, pp. 471–490.) studying slower and longer transient flows. It also complements the numerical studies of a step increase in the flowrate of (He and Seddighi, 2013, “Turbulence in Transient Channel Flow,” J. Fluid Mech., 715, pp. 60–102. and He and Seddighi, 2015, “Transition of Transient Channel Flow After a Change in Reynolds Number,” J. Fluid Mech., 764, pp. 395–427.). The results obtained from the current investigations are qualitatively similar to those obtained previously. Consistent with previous studies, the response of turbulence in the current slow transient flow is again characterized by a laminar-turbulent transition. The initial increase of the flow development among the cases investigated can be categorized as faster, medium, and slower responses. Modifications are made to the equivalent Reynolds number and the initial turbulence intensity proposed earlier in order to account for the slow accelerating flow rates and the continuous change of the bulk velocities of the cases investigated. It has been shown that the critical equivalent Reynolds number based on these modifications and the initial turbulence intensity are well correlated for all cases investigated and a power-law relation is established.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136328784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This effort presents a novel approach to interrogate efficiency for unsteady, undulating propulsion using variable momentum and energy conservation (VMEC) assessments. These integral approaches utilize large amounts of data from computational fluid dynamics (CFD) to address present difficulties associated with separating thrust from drag associated with propelling bodies as well as potentially resolve issues associated with defining a nonzero efficiency for a body in self-propulsion. Such a fundamental issue is addressed through strategic control volume assessments of the momentum and energy conservation equations. In this work, the Method of Manufactured Solutions (MMS) is used to verify the integral-based evaluation approach and better quantify output. The MMS results indicate the method is valid and that one can separate work associated with lift and drag from the energy budget. This separation procedure provides a means to separate propulsive and drag forces. The effort then studies previously validated CFD simulations of heaving and pitching foils to provide insight associated with separating axial forces into their thrust and drag components for highly complex systems. The effort then presents a new efficiency metric that can obtain nonzero efficiencies in self-propulsion. Overall, the results indicate that energy-based assessments provide insight that is a step forward toward isolating loss from propulsive mechanisms and developing proper metrics of efficiency.
{"title":"Onto Quantifying Unsteady Propulsion Characteristics Using Momentum and Energy Control Volume Assessments","authors":"George Loubimov, Michael Kinzel","doi":"10.1115/1.4057036","DOIUrl":"https://doi.org/10.1115/1.4057036","url":null,"abstract":"Abstract This effort presents a novel approach to interrogate efficiency for unsteady, undulating propulsion using variable momentum and energy conservation (VMEC) assessments. These integral approaches utilize large amounts of data from computational fluid dynamics (CFD) to address present difficulties associated with separating thrust from drag associated with propelling bodies as well as potentially resolve issues associated with defining a nonzero efficiency for a body in self-propulsion. Such a fundamental issue is addressed through strategic control volume assessments of the momentum and energy conservation equations. In this work, the Method of Manufactured Solutions (MMS) is used to verify the integral-based evaluation approach and better quantify output. The MMS results indicate the method is valid and that one can separate work associated with lift and drag from the energy budget. This separation procedure provides a means to separate propulsive and drag forces. The effort then studies previously validated CFD simulations of heaving and pitching foils to provide insight associated with separating axial forces into their thrust and drag components for highly complex systems. The effort then presents a new efficiency metric that can obtain nonzero efficiencies in self-propulsion. Overall, the results indicate that energy-based assessments provide insight that is a step forward toward isolating loss from propulsive mechanisms and developing proper metrics of efficiency.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":"1072 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135035241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This work involves studying the effects of plate motion on the turbulent flow behavior of a wall jet stream flowing over a flat plate moving at a constant velocity in a quiescent atmosphere. A modified low-Reynolds-number turbulence model developed by Yang and Shih (YS model) is used to perform the numerical investigation. The YS model involves applying integration to a wall technique to capture the flow and heat transfer phenomenon in the near-wall region. The Reynolds number is taken as 15,000 and Prandtl number of the fluid as 7. The plate motion effect on the flow behavior is observed for the various velocity ratios Up =0−2. The velocity vector diagrams and the local velocity profiles at various axial locations are plotted to analyze the flow pattern variation with the plate velocity. Based on the investigation of velocity profiles, nearly self-similar velocity profiles are noticed for Up=0, 0.5, and 2 whereas for Up=1.0 and 1.5, the velocity profiles display similarity near the wall but diverge away from the wall. The turbulent kinetic energy (TKE) (k) and its dissipation rate (ε) within the viscous shear regime are predicted for moving plate conditions. The dissipation rate appears to be higher for higher velocity ratios. Overall, the plate motion significantly influences the flow field.
{"title":"Investigation of Flow Behavior of Turbulent Wall-Jet in the Viscous Shear Regime with Moving Wall Condition","authors":"Vishwa Mohan Behera, Sushil Kumar Rathore","doi":"10.1115/1.4056998","DOIUrl":"https://doi.org/10.1115/1.4056998","url":null,"abstract":"Abstract This work involves studying the effects of plate motion on the turbulent flow behavior of a wall jet stream flowing over a flat plate moving at a constant velocity in a quiescent atmosphere. A modified low-Reynolds-number turbulence model developed by Yang and Shih (YS model) is used to perform the numerical investigation. The YS model involves applying integration to a wall technique to capture the flow and heat transfer phenomenon in the near-wall region. The Reynolds number is taken as 15,000 and Prandtl number of the fluid as 7. The plate motion effect on the flow behavior is observed for the various velocity ratios Up =0−2. The velocity vector diagrams and the local velocity profiles at various axial locations are plotted to analyze the flow pattern variation with the plate velocity. Based on the investigation of velocity profiles, nearly self-similar velocity profiles are noticed for Up=0, 0.5, and 2 whereas for Up=1.0 and 1.5, the velocity profiles display similarity near the wall but diverge away from the wall. The turbulent kinetic energy (TKE) (k) and its dissipation rate (ε) within the viscous shear regime are predicted for moving plate conditions. The dissipation rate appears to be higher for higher velocity ratios. Overall, the plate motion significantly influences the flow field.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135905067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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