Pub Date : 2023-12-01DOI: 10.47176/jafm.16.12.2028
M. S. Kim, H. S. Seong, J. H. Yang, S. W. Lee, S. W. Choi
The performance a valve has been frequently estimated with numerical methods owing to limitations such as cost and place. In this study, for the triple-offset butterfly valves, the different sizes in various disc-opening cases was numerically conducted using different turbulence models of the two-equation turbulence models of k–ε, k-ω, and Reynolds stress model. The numerical calculations were validated against experimentally obtained valve flow test results. The numerical effect with the different turbulence models were analyzed with respect to the disc-opening cases. From the numerical analysis, the Reynolds stress model exhibits the most pronounced turbulence effects among the various turbulence models showing higher value of Reynolds normal stress near the valve disc region. The sensitivity of the turbulence model constants was examined using the 300 mm valve to observe the sensitivity of the turbulence model parameters in the two-equation turbulence models.
{"title":"Fluid Flow and Effect of Turbulence Model on Large-Sized Triple-Offset Butterfly Valve","authors":"M. S. Kim, H. S. Seong, J. H. Yang, S. W. Lee, S. W. Choi","doi":"10.47176/jafm.16.12.2028","DOIUrl":"https://doi.org/10.47176/jafm.16.12.2028","url":null,"abstract":"The performance a valve has been frequently estimated with numerical methods owing to limitations such as cost and place. In this study, for the triple-offset butterfly valves, the different sizes in various disc-opening cases was numerically conducted using different turbulence models of the two-equation turbulence models of k–ε, k-ω, and Reynolds stress model. The numerical calculations were validated against experimentally obtained valve flow test results. The numerical effect with the different turbulence models were analyzed with respect to the disc-opening cases. From the numerical analysis, the Reynolds stress model exhibits the most pronounced turbulence effects among the various turbulence models showing higher value of Reynolds normal stress near the valve disc region. The sensitivity of the turbulence model constants was examined using the 300 mm valve to observe the sensitivity of the turbulence model parameters in the two-equation turbulence models.","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":" 7","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138618285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-01DOI: 10.47176/jafm.16.12.2029
†. J.L.Cheng, S. Huang, L. Zhou
The serpentine nozzle effectively suppresses infrared radiation and radar signals from advanced aero-engine exhaust system. However, the extreme operating environment of thermal–solid interaction complicates the heat transfer of the flow inside the serpentine nozzle and the structural response of the nozzle itself. In this study, the internal flow heat transfer and the structural response of the serpentine nozzle were investigated numerically. Further, the parameter influence law of wall thickness was explored. The results show that the mechanism of the thermal-solid interaction is formed through the data transfer of the heat flux and the temperature at the interface between the flow field and structure field. The heat flux distribution of the nozzle under the bending configuration is non-uniform. The upper wall surface at the first bend and the lower wall surface at the second bend exhibit the highest heat flux. In the structural response, the temperature extremes appear on the upper wall at the first bend and the lower wall at the second bend. Subsequently, they shift to the inlet. The stress in the nozzle with a thickness of 3 mm first increases and then decreases, with a maximum stress of 139.43 MPa at t = 51.20 s. For nozzles of different thicknesses, the positions of the maximum stresses all appear at the outlet and the moments concentrate in approximately 50 s. However, with the increase in thickness, the maximum stress of nozzle increases continuously, and the maximum increases by 93% compared with the minimum.
{"title":"Thermal–Solid Interaction Study of Serpentine Nozzle and Analysis on Structural Response Law","authors":"†. J.L.Cheng, S. Huang, L. Zhou","doi":"10.47176/jafm.16.12.2029","DOIUrl":"https://doi.org/10.47176/jafm.16.12.2029","url":null,"abstract":"The serpentine nozzle effectively suppresses infrared radiation and radar signals from advanced aero-engine exhaust system. However, the extreme operating environment of thermal–solid interaction complicates the heat transfer of the flow inside the serpentine nozzle and the structural response of the nozzle itself. In this study, the internal flow heat transfer and the structural response of the serpentine nozzle were investigated numerically. Further, the parameter influence law of wall thickness was explored. The results show that the mechanism of the thermal-solid interaction is formed through the data transfer of the heat flux and the temperature at the interface between the flow field and structure field. The heat flux distribution of the nozzle under the bending configuration is non-uniform. The upper wall surface at the first bend and the lower wall surface at the second bend exhibit the highest heat flux. In the structural response, the temperature extremes appear on the upper wall at the first bend and the lower wall at the second bend. Subsequently, they shift to the inlet. The stress in the nozzle with a thickness of 3 mm first increases and then decreases, with a maximum stress of 139.43 MPa at t = 51.20 s. For nozzles of different thicknesses, the positions of the maximum stresses all appear at the outlet and the moments concentrate in approximately 50 s. However, with the increase in thickness, the maximum stress of nozzle increases continuously, and the maximum increases by 93% compared with the minimum.","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":"316 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138625753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-01DOI: 10.47176/jafm.16.12.1982
†. A.Sharhan, A. Al-Muslimawi
In this study we examine the flow of inelastic fluids with various shear properties in axisymmetric contractions with various contraction ratios are selected as 4:1, 6:1 and 8:1 with both rounded-corner and sharp. Particular attention is paid to the effect of shear thickening and shear thinning upon the solution behavior. Power-law inelastic model is employed coupling with the conservation of momentum equation and continuity equation. The numerical simulation of such fluid is performed by using the Taylor Galerkin pressure correction (T-G/P-C) finite element algorithm. The effects of geometry structure and many factors such as Reynolds number (Re) and the parameters of power law model are presented in this study. Particularly, in this study we are focused on the influence of these factors on the solution components and the level of convergence. This research was a comparative study between sharp and rounded-corner contraction geometries with a ratio of 4:1, and to another comparative study among sharp contraction geometries with ratios of 4:1, 6:1, and 8:1. The practical implications of this study focused on vortex length and the impact of varying the parameters of the power law model and the Reynolds number (Re) on it for 4:1 contraction flow. The study dealt with the effect of different geometries on the rates of convergence of velocity and pressure as well as the characteristics of axial velocity and pressure on the axis of symmetry.
{"title":"Inelastic Solution for Power Law Fluid with Taylor Galerkin-Pressure Correction Finite Element Method: Axisymmetric Contraction Flows","authors":"†. A.Sharhan, A. Al-Muslimawi","doi":"10.47176/jafm.16.12.1982","DOIUrl":"https://doi.org/10.47176/jafm.16.12.1982","url":null,"abstract":"In this study we examine the flow of inelastic fluids with various shear properties in axisymmetric contractions with various contraction ratios are selected as 4:1, 6:1 and 8:1 with both rounded-corner and sharp. Particular attention is paid to the effect of shear thickening and shear thinning upon the solution behavior. Power-law inelastic model is employed coupling with the conservation of momentum equation and continuity equation. The numerical simulation of such fluid is performed by using the Taylor Galerkin pressure correction (T-G/P-C) finite element algorithm. The effects of geometry structure and many factors such as Reynolds number (Re) and the parameters of power law model are presented in this study. Particularly, in this study we are focused on the influence of these factors on the solution components and the level of convergence. This research was a comparative study between sharp and rounded-corner contraction geometries with a ratio of 4:1, and to another comparative study among sharp contraction geometries with ratios of 4:1, 6:1, and 8:1. The practical implications of this study focused on vortex length and the impact of varying the parameters of the power law model and the Reynolds number (Re) on it for 4:1 contraction flow. The study dealt with the effect of different geometries on the rates of convergence of velocity and pressure as well as the characteristics of axial velocity and pressure on the axis of symmetry.","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":"130 3","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138622492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.47176/jafm.16.11.1940
M. E. B. Agha, A. A. Ras†, K. Hamdaoui
Global approval of the use of fluid viscous dampers to control the buildings response against dynamic loadings is growing. The idea behind incorporating additional dampers is that they will reduce most of the energy that is transmitted to the building during shaking event. The objective of this work is to identify and enhance the design parameters that control the nonlinear behaviour of fluid viscous damper subjected to sinusoidal excitation. For this, a numerical model of the flow inside the dissipater has been carried out based on finite volume method. A novel approach has been adopted to simulate elastic behaviour of the fluid, taking into account its compressibility by using the Murnaghan equation of state. A comparison between the calculations of the proposed model and the experimental tests was carried out. The model proved to be sufficiently accurate. A fluid flow analysis was then conducted to fully understand the internal mechanism of the damper. A parametric study was then performed by varying aspects such as dimensions, geometric relationships between components and fluid properties in order to better understand their effect on the non-linear behaviour of the device. The results highlight the relationship between the parameters governing the shear thinning behaviour of the fluid and the non-linearity exponent of the damper. This makes it possible to better control the non-linear behaviour of the device by selecting the appropriate silicone oil and the appropriate geometric dimensions of its components.
{"title":"Investigation of Rheological and Geometric Properties Effect on Nonlinear Behaviour of Fluid Viscous Dampers","authors":"M. E. B. Agha, A. A. Ras†, K. Hamdaoui","doi":"10.47176/jafm.16.11.1940","DOIUrl":"https://doi.org/10.47176/jafm.16.11.1940","url":null,"abstract":"Global approval of the use of fluid viscous dampers to control the buildings response against dynamic loadings is growing. The idea behind incorporating additional dampers is that they will reduce most of the energy that is transmitted to the building during shaking event. The objective of this work is to identify and enhance the design parameters that control the nonlinear behaviour of fluid viscous damper subjected to sinusoidal excitation. For this, a numerical model of the flow inside the dissipater has been carried out based on finite volume method. A novel approach has been adopted to simulate elastic behaviour of the fluid, taking into account its compressibility by using the Murnaghan equation of state. A comparison between the calculations of the proposed model and the experimental tests was carried out. The model proved to be sufficiently accurate. A fluid flow analysis was then conducted to fully understand the internal mechanism of the damper. A parametric study was then performed by varying aspects such as dimensions, geometric relationships between components and fluid properties in order to better understand their effect on the non-linear behaviour of the device. The results highlight the relationship between the parameters governing the shear thinning behaviour of the fluid and the non-linearity exponent of the damper. This makes it possible to better control the non-linear behaviour of the device by selecting the appropriate silicone oil and the appropriate geometric dimensions of its components.","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48892391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.47176/jafm.16.11.1857
M. Heidarian, †. A.Madadi, M. Boroomand
Nowadays, optimization methods have been considered as a practical tool to improve the performance of turbo-machines. For this purpose, the numerical study of the aerodynamic flow of the NASA Rotor-67 axial compressor has been investigated, and the results of this three-dimensional simulation show good agreement with experimental data. Then, the blade stacking line is changed using lean and sweep for Rotor-67 to improve the compressor performance. The third-order polynomial is selected to generate the lean and sweep changes from the hub to the shroud. The compressor flow field is solved by a Reynolds averaged Navier-Stokes solver. The genetic algorithm, coupled with the artificial neural networks, is implemented to find the optimum values for blade lean and sweep. Considering the three objective functions of pressure ratio, mass flow rate, and isentropic efficiency, the optimized rotor is obtained using the optimization algorithm. Two geometries are obtained using the optimization algorithm. The results of the optimized compressor include improving the isentropic efficiency, pressure ratio, and mass flow equal to 0.57%, 0.93%, and 1.8%, respectively. After compressor optimization, the effect of the changes in the compressor performance parameters is studied on a single spool turbojet engine. The engine is modeled by analyzing the Brayton thermodynamic cycle of the assumed turbojet engine under design point operating conditions. Results show that for the best test case, the engine with the optimized rotor, the thrust, and SFC are improved by 1.86% and 0.21%, respectively.
{"title":"Three-Dimensional Optimization of Blade Lean and Sweep for an Axial Compressor to Improve the Engine Performance","authors":"M. Heidarian, †. A.Madadi, M. Boroomand","doi":"10.47176/jafm.16.11.1857","DOIUrl":"https://doi.org/10.47176/jafm.16.11.1857","url":null,"abstract":"Nowadays, optimization methods have been considered as a practical tool to improve the performance of turbo-machines. For this purpose, the numerical study of the aerodynamic flow of the NASA Rotor-67 axial compressor has been investigated, and the results of this three-dimensional simulation show good agreement with experimental data. Then, the blade stacking line is changed using lean and sweep for Rotor-67 to improve the compressor performance. The third-order polynomial is selected to generate the lean and sweep changes from the hub to the shroud. The compressor flow field is solved by a Reynolds averaged Navier-Stokes solver. The genetic algorithm, coupled with the artificial neural networks, is implemented to find the optimum values for blade lean and sweep. Considering the three objective functions of pressure ratio, mass flow rate, and isentropic efficiency, the optimized rotor is obtained using the optimization algorithm. Two geometries are obtained using the optimization algorithm. The results of the optimized compressor include improving the isentropic efficiency, pressure ratio, and mass flow equal to 0.57%, 0.93%, and 1.8%, respectively. After compressor optimization, the effect of the changes in the compressor performance parameters is studied on a single spool turbojet engine. The engine is modeled by analyzing the Brayton thermodynamic cycle of the assumed turbojet engine under design point operating conditions. Results show that for the best test case, the engine with the optimized rotor, the thrust, and SFC are improved by 1.86% and 0.21%, respectively.","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41553417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.47176/jafm.16.11.1773
B. B. Ndebele, I. M. A. Gledhill
The dynamics of two-dimensional vortex shedding from a rotating cluster of three cylinders was investigated using Computational Fluid Dynamics (CFD) and Dynamic Mode Decomposition (DMD). The cluster was formed from three circles with equal diameters in mutual contact and allowed to rotate about an axis passing through the cluster centroid. While immersed in an incompressible fluid with Reynolds number of 100, the cluster was allowed to rotate at non-dimensionalised rotation rates (Ω) between 0 and 1. The rotation rates were non-dimensionalised using the free-stream velocity and the cluster characteristic diameter, the latter being equal to the diameter of the circle circumscribing the cluster. CFD simulations were performed using StarCCM+. Dynamic Mode Decomposition based on the two-dimensional vorticity field was used to decompose the field into its fundamental mode-shapes. It was then possible to relate the mode-shapes to lift and drag. Transverse and longitudinal mode-shapes corresponded to lift and drag, respectively. Lift–drag polars showed a more complex pattern dependent on Ω in which the flow fields could be classified into three regimes: Ω less than 0.3, greater than 0.5, and between 0.3 and 0.5. In general, the polars formed open curves in contrast to those of static cylinders, which were closed. However, some cases, such as Ω = 0.01, 0.22, and 0.28, formed closed curves. Whether a lift-drag polar was closed or open was deduced to be determined by the ratio of Strouhal numbers calculated using lift and drag time series, with closed curves forming when the ratio is an integer.
{"title":"Two Dimensional Vortex Shedding from a Rotating Cluster of Cylinders","authors":"B. B. Ndebele, I. M. A. Gledhill","doi":"10.47176/jafm.16.11.1773","DOIUrl":"https://doi.org/10.47176/jafm.16.11.1773","url":null,"abstract":"The dynamics of two-dimensional vortex shedding from a rotating cluster of three cylinders was investigated using Computational Fluid Dynamics (CFD) and Dynamic Mode Decomposition (DMD). The cluster was formed from three circles with equal diameters in mutual contact and allowed to rotate about an axis passing through the cluster centroid. While immersed in an incompressible fluid with Reynolds number of 100, the cluster was allowed to rotate at non-dimensionalised rotation rates (Ω) between 0 and 1. The rotation rates were non-dimensionalised using the free-stream velocity and the cluster characteristic diameter, the latter being equal to the diameter of the circle circumscribing the cluster. CFD simulations were performed using StarCCM+. Dynamic Mode Decomposition based on the two-dimensional vorticity field was used to decompose the field into its fundamental mode-shapes. It was then possible to relate the mode-shapes to lift and drag. Transverse and longitudinal mode-shapes corresponded to lift and drag, respectively. Lift–drag polars showed a more complex pattern dependent on Ω in which the flow fields could be classified into three regimes: Ω less than 0.3, greater than 0.5, and between 0.3 and 0.5. In general, the polars formed open curves in contrast to those of static cylinders, which were closed. However, some cases, such as Ω = 0.01, 0.22, and 0.28, formed closed curves. Whether a lift-drag polar was closed or open was deduced to be determined by the ratio of Strouhal numbers calculated using lift and drag time series, with closed curves forming when the ratio is an integer.","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43138917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.47176/jafm.16.11.1931
E. Azadi, M. Taeibi
There are various situations of drop impact on solid surfaces widely occurred in natural phenomenon or used in different industrial applications. However, comparing and classifying these drop impact situations is not easy due to different states of the parameters affecting drop impact dynamics. In this article, a unified transformation framework is proposed to study various situations of vertical/oblique drop impact on horizontal/inclined stationary/moving flat surfaces with/without a crossflow. This simple framework consists of a coordinate with normal and tangential axes on a horizontal stationary surface. For each drop impact situation, the drop velocity, gravitational acceleration, possible induced flow due to the moving surface, and possible crossflow are transformed into the framework. Comparing the transformed versions of considered drop impact situations facilitates identification of their physical similarities/differences and determines which situations (and under what conditions) lead to identical results and can be used interchangeably. Although common situations of drop impact on moving surfaces (having tangential component of surface velocity) lead to asymmetric drop spreading, the possibility of symmetric drop spreading on moving surfaces is demonstrated and analyzed using the proposed transformation framework. This interesting possibility means that for related production lines or experimental setups, where symmetrical drop spreading is required, the surface does not need to be stationary. In such applications/setups, the use of moving surfaces (rather than stationary surfaces) can considerably accelerate the symmetric drop impact process. Our simulation results of several of the considered drop impact situations well confirm the facilities/predictions of the proposed transformation framework.
{"title":"A Unified Transformation Framework for Studying Various Situations of Vertical/Oblique Drop Impact on Horizontal/Inclined Stationary/Moving Flat Surfaces","authors":"E. Azadi, M. Taeibi","doi":"10.47176/jafm.16.11.1931","DOIUrl":"https://doi.org/10.47176/jafm.16.11.1931","url":null,"abstract":"There are various situations of drop impact on solid surfaces widely occurred in natural phenomenon or used in different industrial applications. However, comparing and classifying these drop impact situations is not easy due to different states of the parameters affecting drop impact dynamics. In this article, a unified transformation framework is proposed to study various situations of vertical/oblique drop impact on horizontal/inclined stationary/moving flat surfaces with/without a crossflow. This simple framework consists of a coordinate with normal and tangential axes on a horizontal stationary surface. For each drop impact situation, the drop velocity, gravitational acceleration, possible induced flow due to the moving surface, and possible crossflow are transformed into the framework. Comparing the transformed versions of considered drop impact situations facilitates identification of their physical similarities/differences and determines which situations (and under what conditions) lead to identical results and can be used interchangeably. Although common situations of drop impact on moving surfaces (having tangential component of surface velocity) lead to asymmetric drop spreading, the possibility of symmetric drop spreading on moving surfaces is demonstrated and analyzed using the proposed transformation framework. This interesting possibility means that for related production lines or experimental setups, where symmetrical drop spreading is required, the surface does not need to be stationary. In such applications/setups, the use of moving surfaces (rather than stationary surfaces) can considerably accelerate the symmetric drop impact process. Our simulation results of several of the considered drop impact situations well confirm the facilities/predictions of the proposed transformation framework.","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46652690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.47176/jafm.16.11.1973
Z. Lin, F. Yang, X. Xu, X. Jin, M. Chen, G. Xu
Tubular pump devices offer advantages such as low hydraulic losses, a simple structure, and easy maintenance. They find extensive application in areas such as irrigation, flood control, and water diversion. The performance and security of the pump are directly impacted by the contact between the impeller and guide vane. The matching relationship between the number of impeller blades and guide vanes significantly influences this interaction in tubular pump devices. To explore this impact, a Very-Large-Eddy Simulation turbulence model was employed to simulate the 3D flow fields of six different number matching relationships in a shaft tubular pump device. The analysis focused on the energy performance of the different schemes, the flow distribution of the guide vanes, and the velocity circulation at the guide vanes’ outlet. Entropy theory and energy gradient theory were employed to understand how the number matching relationship influences energy performance. Additionally, pressure pulsations were analyzed at the impeller and guide vanes for different matching configurations. The results indicate that although increasing the number of impeller blades can lead to higher water circulation, increased energy, and potentially unstable water flow, an increase in impeller blades number results in improved flow distribution in each guide vane groove, leading to an overall enhancement in the efficiency of the pump device. Similarly, increasing the number of guide vanes may increase the non-uniformity of the guide vane flow rate, but it also enhances the ability of the guide vanes to regulate water circulation and recover energy, thereby benefiting the overall efficiency.
{"title":"Influence Analysis of Impeller-Guide Vane Matching on Energy and Pressure Pulsation in a Tubular Pump Device","authors":"Z. Lin, F. Yang, X. Xu, X. Jin, M. Chen, G. Xu","doi":"10.47176/jafm.16.11.1973","DOIUrl":"https://doi.org/10.47176/jafm.16.11.1973","url":null,"abstract":"Tubular pump devices offer advantages such as low hydraulic losses, a simple structure, and easy maintenance. They find extensive application in areas such as irrigation, flood control, and water diversion. The performance and security of the pump are directly impacted by the contact between the impeller and guide vane. The matching relationship between the number of impeller blades and guide vanes significantly influences this interaction in tubular pump devices. To explore this impact, a Very-Large-Eddy Simulation turbulence model was employed to simulate the 3D flow fields of six different number matching relationships in a shaft tubular pump device. The analysis focused on the energy performance of the different schemes, the flow distribution of the guide vanes, and the velocity circulation at the guide vanes’ outlet. Entropy theory and energy gradient theory were employed to understand how the number matching relationship influences energy performance. Additionally, pressure pulsations were analyzed at the impeller and guide vanes for different matching configurations. The results indicate that although increasing the number of impeller blades can lead to higher water circulation, increased energy, and potentially unstable water flow, an increase in impeller blades number results in improved flow distribution in each guide vane groove, leading to an overall enhancement in the efficiency of the pump device. Similarly, increasing the number of guide vanes may increase the non-uniformity of the guide vane flow rate, but it also enhances the ability of the guide vanes to regulate water circulation and recover energy, thereby benefiting the overall efficiency.","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49471556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.47176/jafm.16.11.1767
A. Meziane, M. Hachemi, M. Kessal, M. Imoula
This paper investigates numerically the bubble-type vortex breakdown apparition in the case of closed rotating flows of a viscous, axisymmetric, and incompressible fluid. First, a truncated conical/cylindrical cavity of spherical end disks is used to simulate and analyze the vortex structure under rigid surface conditions. The geometric effects of the enclosure are also studied. Vortex breakdown is demonstrated beyond the lower disk rotation rate threshold by introducing the no-slip condition imposed on the upper wall. The objective is to explore ways of controlling the evolution of this physical event by modifying the confinement conditions upstream of the vortex rupture. Particular attention is also paid to the effective kinematic viscosity, thermal diffusivity and geometric control of recirculation zones on the axis of rotation (axial bubble type). The second geometry consists of a spherical annulus formed by two concentric hemispheres in differential rotation under plat-free surface conditions. The results show that rotation of the inner hemisphere induces a vortex bubble on the polar axis. In contrast, the outer hemisphere rotation induces a toroidal vortex on the equator.
{"title":"A Wall Effects and Means of Controlling the Evolution of Swirling Flows with Vortex Breakdown","authors":"A. Meziane, M. Hachemi, M. Kessal, M. Imoula","doi":"10.47176/jafm.16.11.1767","DOIUrl":"https://doi.org/10.47176/jafm.16.11.1767","url":null,"abstract":"This paper investigates numerically the bubble-type vortex breakdown apparition in the case of closed rotating flows of a viscous, axisymmetric, and incompressible fluid. First, a truncated conical/cylindrical cavity of spherical end disks is used to simulate and analyze the vortex structure under rigid surface conditions. The geometric effects of the enclosure are also studied. Vortex breakdown is demonstrated beyond the lower disk rotation rate threshold by introducing the no-slip condition imposed on the upper wall. The objective is to explore ways of controlling the evolution of this physical event by modifying the confinement conditions upstream of the vortex rupture. Particular attention is also paid to the effective kinematic viscosity, thermal diffusivity and geometric control of recirculation zones on the axis of rotation (axial bubble type). The second geometry consists of a spherical annulus formed by two concentric hemispheres in differential rotation under plat-free surface conditions. The results show that rotation of the inner hemisphere induces a vortex bubble on the polar axis. In contrast, the outer hemisphere rotation induces a toroidal vortex on the equator.","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41727919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.47176/jafm.16.11.1845
W. H. Goo, P. B. Ganesan, K. W. Yong, M. Y. Ahmad, Y. H. Yau, F. Hamad
This paper investigates the air bubble size and its transition in a horizontal tube of 700 mm. The tube was assembled with a venturi-nozzle bubble generator. Air and water flow-rates vary in the present study. The data collection mainly used high-speed camera to capture the bubbles at different distances along the horizontal tube at water flow-rates (Qw) of 120-170 litre per min (LPM) and air flow-rates (Qa) of 2-10 LPM. MATLAB was used in image processing for evaluating the bubble size. The data interpretation used YW dimensionless parameter in representing the height of the bubbles’ vertical rise in the horizontal tube. The bubble size along the horizontal tube was characterized by the Weber number as well. The type of two-phase (water-air bubbles) flow along the horizontal tube from the venturi-nozzle bubble generator was determined using flow pattern map and Lockhart-Martinelli parameter. The bubble generator produced bubbles in the range of 0.8-3.1 mm at the inlet of horizontal tube. The bubble diameters increased as the bubbles moved horizontally from inlet to outlet of the horizontal tube and this finding was statistically significant. The vertical rise height of bubbles along the horizontal tube at different water and air flow-rates had been quantified and compared. The vertical rise height of bubbles increased axially from 41 % to 89 % from inlet to outlet of the horizontal tube. The bubbles’ vertical rise height increased when either the air flow-rate or water flow-rate is reduced. The mean Weber number increased along the horizontal tube due to an increase in bubble size. The decrease in water flow-rate caused a decrease in the mean Weber number. The Lockhart-Martinelli parameter of the water-air bubbles flow in the horizontal tube was within 0.58-2.94, indicating that it was a multiphase flow. The findings from this study give fundamental insight into bubble dynamics behaviour in its horizontal transition. This study focuses on the size and transition of air bubbles produced by venturi-nozzle bubble generator along a horizontal tube at different water and air flow-rates, unlike previous studies which only investigate the air bubbles inside or near bubble generator. These findings are very useful for practical industrial applications because the exact air bubble size before being used is known.
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