Sen Li, Juan Liao, Chuangxin He, Chunjing Song, Yingzheng Liu, Yun Zhong
In this work, a large-scale mock-up of a compact complex system integrating a steam generator (SG) and a reactor coolant pump (RCP) is considered. The three-dimensional turbulent flow in the steam generator channel head (SGCH) is measured in detail. Dual-orthogonal-plane particle image velocimetry (PIV) is employed to extract high-resolution flow information in two orthogonal planes. Two separate measurements are first made to see the three-dimensional time-mean flow dynamics and the statistical quantities in the two planes. These measurements highlight two distinct flow phenomena: jet arrays and massive turbulent separation bubbles (TSBs). These patterns are attributed to mass flow redistribution in the U-shaped tubes. Proper orthogonal decomposition (POD) identifies the first POD mode as corresponding to the TSB breathing-like motion, which significantly intensifies the side view streamwise velocity fluctuations, leading to them reaching 370% of the local mean velocity. To examine the unsteady behavior of massively separated regions, the dual-orthogonal-plane PIV system is then synchronized to simultaneously measure variations in the flow fields, and the missing data due to illumination interference is reconstructed using gappy POD. The synchronized analysis reveals a direct relationship between the low-frequency fluctuations in the side and front views. These fluctuations are in phase across both views, indicating a synchronized behavior that spans the entire field. This large-scale low-frequency breathing motion has critical implications for numerical simulations and sheds light on the unsteady behavior of the RCP system within the SGCH.
在这项工作中，考虑了一个集成了蒸汽发生器（SG）和反应堆冷却剂泵（RCP）的紧凑型复杂系统的大型模型。详细测量了蒸汽发生器通道头（SGCH）中的三维湍流。采用双正交平面粒子图像测速仪（PIV）提取两个正交平面的高分辨率流动信息。首先进行两次单独测量，以观察两个平面上的三维时均流动动态和统计量。这些测量结果突出显示了两种截然不同的流动现象：喷流阵列和大量湍流分离气泡（TSBs）。这些模式归因于 U 形管中的质量流再分布。适当正交分解（POD）确定了第一种 POD 模式与 TSB 呼吸运动相对应，它显著增强了侧视流向速度波动，使其达到局部平均速度的 370%。为了研究大规模分离区域的非稳态行为，双正交平面 PIV 系统被同步化，以同时测量流场的变化，并使用 gappy POD 重构由于光照干扰而缺失的数据。同步分析显示，侧视图和正视图中的低频波动之间存在直接关系。这些波动在两个视图中的相位是一致的，这表明在整个视野中存在同步行为。这种大规模的低频呼吸运动对数值模拟具有重要意义，并揭示了 SGCH 内 RCP 系统的不稳定行为。
{"title":"Dual-Orthogonal-Plane Particle Image Velocimetry Measurement of the Turbulent Flow in the Channel Head of a Large-Scale Steam Generator Mock-Up","authors":"Sen Li, Juan Liao, Chuangxin He, Chunjing Song, Yingzheng Liu, Yun Zhong","doi":"10.1115/1.4064754","DOIUrl":"https://doi.org/10.1115/1.4064754","url":null,"abstract":"\u0000 In this work, a large-scale mock-up of a compact complex system integrating a steam generator (SG) and a reactor coolant pump (RCP) is considered. The three-dimensional turbulent flow in the steam generator channel head (SGCH) is measured in detail. Dual-orthogonal-plane particle image velocimetry (PIV) is employed to extract high-resolution flow information in two orthogonal planes. Two separate measurements are first made to see the three-dimensional time-mean flow dynamics and the statistical quantities in the two planes. These measurements highlight two distinct flow phenomena: jet arrays and massive turbulent separation bubbles (TSBs). These patterns are attributed to mass flow redistribution in the U-shaped tubes. Proper orthogonal decomposition (POD) identifies the first POD mode as corresponding to the TSB breathing-like motion, which significantly intensifies the side view streamwise velocity fluctuations, leading to them reaching 370% of the local mean velocity. To examine the unsteady behavior of massively separated regions, the dual-orthogonal-plane PIV system is then synchronized to simultaneously measure variations in the flow fields, and the missing data due to illumination interference is reconstructed using gappy POD. The synchronized analysis reveals a direct relationship between the low-frequency fluctuations in the side and front views. These fluctuations are in phase across both views, indicating a synchronized behavior that spans the entire field. This large-scale low-frequency breathing motion has critical implications for numerical simulations and sheds light on the unsteady behavior of the RCP system within the SGCH.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"55 25","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139844511","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}
E. Merzari, Victor Coppo Leite, Jun Fang, D. Shaver, Misun Min, S. Kerkemeier, Paul Fischer, A. Tomboulides
Development and application of the open-source GPU-based fluid-thermal simulation code, NekRS, is described. Time advancement is based on an efficient kth-order accurate time split formulation coupled with scalable iterative solvers. Spatial discretization is based on the high-order spectral element method (SEM), which allows fast, low-memory, matrix-free operator evaluation. Recent developments include support for nonconforming meshes using overset grids and GPU-based Lagrangian particle tracking. Results of large eddy simulations of atmospheric boundary layers for wind-energy applications and extensive nuclear energy applications are presented.
{"title":"Energy Exascale CFD Simulations with the Spectral Element Method","authors":"E. Merzari, Victor Coppo Leite, Jun Fang, D. Shaver, Misun Min, S. Kerkemeier, Paul Fischer, A. Tomboulides","doi":"10.1115/1.4064659","DOIUrl":"https://doi.org/10.1115/1.4064659","url":null,"abstract":"\u0000 Development and application of the open-source GPU-based fluid-thermal simulation code, NekRS, is described. Time advancement is based on an efficient kth-order accurate time split formulation coupled with scalable iterative solvers. Spatial discretization is based on the high-order spectral element method (SEM), which allows fast, low-memory, matrix-free operator evaluation. Recent developments include support for nonconforming meshes using overset grids and GPU-based Lagrangian particle tracking. Results of large eddy simulations of atmospheric boundary layers for wind-energy applications and extensive nuclear energy applications are presented.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"127 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139801840","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}
A formulation is developed using volume-averaging and the concept of added mass to derive a hyperbolic system of governing equations for modeling turbulent, dense granular flows. The Large Eddy Simulations (LES) framework is employed for the fluid phase, whereas the solid phase equations are based on enlarged Kinetic Theory concepts. To obtain the LES equations, the volume-averaged equations are filtered and the filtered terms not directly computable from the LES solution are generically modeled. Additionally, the pseudo-turbulent kinetic energy (PTKE) is included in the formulation, and it is shown how its contribution is distinct from turbulence and leads to different terms that must be modeled in the conservation equations. Volume-averaging of the continuity, momentum and energy equations result in many integrals that are used to rigorously define the meaning of terms that have only been included heuristically in existing formulations. Simulations with this model are conducted in a configuration representing the interaction of a turbulent supersonic jet with a bed of solid particles. The results are analyzed to demonstrate hyperbolicity. Comparisons of results from a model including PTKE and one excluding show that the inclusion of PTKE has no role in bestowing hyperbolicity to the model, and furthermore does not affect the macroscopic aspects of the crater. Comparisons between results obtained with a hyperbolic model and a model that is hyperbolic everywhere except in regions of particle/fluid interaction show that the macroscopic crater aspects are different, affecting the crater shape and topography.
利用体积平均法和附加质量概念开发了一种公式，从而推导出用于模拟湍流、致密颗粒流的双曲线控制方程系统。流体相采用大涡流模拟（LES）框架，固相方程则基于放大的动力学理论概念。为了获得 LES 方程，对体积平均方程进行了过滤，并对 LES 解决方案中无法直接计算的过滤项进行了通用建模。此外，假湍流动能（PTKE）也包含在公式中，并说明了其贡献如何有别于湍流，并导致必须在守恒方程中建模的不同项。连续性方程、动量方程和能量方程的体积平均化产生了许多积分，这些积分用于严格定义现有公式中启发式包含的术语的含义。该模型模拟了湍流超音速射流与固体颗粒床的相互作用。分析结果证明了双曲性。对包含 PTKE 的模型和不包含 PTKE 的模型的结果进行比较后发现，包含 PTKE 对模型的双曲性没有任何作用，而且不会影响火山口的宏观方面。比较双曲线模型和除粒子/流体相互作用区域外各处均为双曲线的模型得出的结果表明，陨石坑的宏观方面是不同的，会影响陨石坑的形状和地形。
{"title":"A Volume-Averaged Hyperbolic System of Governing Equations for Granular Turbulent Flow Modeling with Phase Change","authors":"Kaushik Balakrishnan, Josette R. Bellan","doi":"10.1115/1.4064660","DOIUrl":"https://doi.org/10.1115/1.4064660","url":null,"abstract":"\u0000 A formulation is developed using volume-averaging and the concept of added mass to derive a hyperbolic system of governing equations for modeling turbulent, dense granular flows. The Large Eddy Simulations (LES) framework is employed for the fluid phase, whereas the solid phase equations are based on enlarged Kinetic Theory concepts. To obtain the LES equations, the volume-averaged equations are filtered and the filtered terms not directly computable from the LES solution are generically modeled. Additionally, the pseudo-turbulent kinetic energy (PTKE) is included in the formulation, and it is shown how its contribution is distinct from turbulence and leads to different terms that must be modeled in the conservation equations. Volume-averaging of the continuity, momentum and energy equations result in many integrals that are used to rigorously define the meaning of terms that have only been included heuristically in existing formulations. Simulations with this model are conducted in a configuration representing the interaction of a turbulent supersonic jet with a bed of solid particles. The results are analyzed to demonstrate hyperbolicity. Comparisons of results from a model including PTKE and one excluding show that the inclusion of PTKE has no role in bestowing hyperbolicity to the model, and furthermore does not affect the macroscopic aspects of the crater. Comparisons between results obtained with a hyperbolic model and a model that is hyperbolic everywhere except in regions of particle/fluid interaction show that the macroscopic crater aspects are different, affecting the crater shape and topography.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"15 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139800437","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}
A formulation is developed using volume-averaging and the concept of added mass to derive a hyperbolic system of governing equations for modeling turbulent, dense granular flows. The Large Eddy Simulations (LES) framework is employed for the fluid phase, whereas the solid phase equations are based on enlarged Kinetic Theory concepts. To obtain the LES equations, the volume-averaged equations are filtered and the filtered terms not directly computable from the LES solution are generically modeled. Additionally, the pseudo-turbulent kinetic energy (PTKE) is included in the formulation, and it is shown how its contribution is distinct from turbulence and leads to different terms that must be modeled in the conservation equations. Volume-averaging of the continuity, momentum and energy equations result in many integrals that are used to rigorously define the meaning of terms that have only been included heuristically in existing formulations. Simulations with this model are conducted in a configuration representing the interaction of a turbulent supersonic jet with a bed of solid particles. The results are analyzed to demonstrate hyperbolicity. Comparisons of results from a model including PTKE and one excluding show that the inclusion of PTKE has no role in bestowing hyperbolicity to the model, and furthermore does not affect the macroscopic aspects of the crater. Comparisons between results obtained with a hyperbolic model and a model that is hyperbolic everywhere except in regions of particle/fluid interaction show that the macroscopic crater aspects are different, affecting the crater shape and topography.
利用体积平均法和附加质量概念开发了一种公式，从而推导出用于模拟湍流、致密颗粒流的双曲线控制方程系统。流体相采用大涡流模拟（LES）框架，固相方程则基于放大的动力学理论概念。为了获得 LES 方程，对体积平均方程进行了过滤，并对 LES 解决方案中无法直接计算的过滤项进行了通用建模。此外，假湍流动能（PTKE）也包含在公式中，并说明了其贡献如何有别于湍流，并导致必须在守恒方程中建模的不同项。连续性方程、动量方程和能量方程的体积平均化产生了许多积分，这些积分用于严格定义现有公式中启发式包含的术语的含义。该模型模拟了湍流超音速射流与固体颗粒床的相互作用。分析结果证明了双曲性。对包含 PTKE 的模型和不包含 PTKE 的模型的结果进行比较后发现，包含 PTKE 对模型的双曲性没有任何作用，而且不会影响火山口的宏观方面。比较双曲线模型和除粒子/流体相互作用区域外各处均为双曲线的模型得出的结果表明，陨石坑的宏观方面是不同的，会影响陨石坑的形状和地形。
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E. Merzari, Victor Coppo Leite, Jun Fang, D. Shaver, Misun Min, S. Kerkemeier, Paul Fischer, A. Tomboulides
Development and application of the open-source GPU-based fluid-thermal simulation code, NekRS, is described. Time advancement is based on an efficient kth-order accurate time split formulation coupled with scalable iterative solvers. Spatial discretization is based on the high-order spectral element method (SEM), which allows fast, low-memory, matrix-free operator evaluation. Recent developments include support for nonconforming meshes using overset grids and GPU-based Lagrangian particle tracking. Results of large eddy simulations of atmospheric boundary layers for wind-energy applications and extensive nuclear energy applications are presented.
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Saadia Afridi, Tariq Amin Khan, Imran Shah, Yasir Ali, M. N. M. Qadri, Wei Li
Due to its ability to maximize thrust-vectoring performance, the bypass dual throat nozzle (BDTN) has an advantage over other fluidic vectoring controls. In this study, numerical simulation is performed to analyze the flow characteristics and performance parameters of an aircraft engine with three different nozzle configurations. The nozzle of a representative engine i.e., an F100 engine was selected as a model geometry to test the efficiency obtained by BDTN. The present investigation has shown that implementing a bypass channel on a real geometry nozzle has no significant effects on thrust vectoring performance in vectoring mode. Although the real geometry scheme has a higher thrust and a discharge coefficient, the smaller cavity length resulted in lower vectoring angles. Modifying the real geometry nozzle according to the BDTN configuration significantly improved the thrust vectoring performance. However, the V-shaped bypass passage flow in the modified geometry scheme imposed unnecessary total pressure losses in the nozzle. A geometry scheme that utilized an arc-shaped rather than a V-shaped bypass passage is considered in this research and found to present minimize pressure losses. A total increase of 2% and 3.5% is hereby reported, for thrust and discharge coefficients respectively. A decrease of 6% is reported in the thrust vectoring angle under an improved geometrical scheme. Out of three geometries, the real geometry scheme reported negligible thrust vectoring performance, while modified and improved geometry schemes indicated improved thrust vectoring performance without substantially changing the engine states.
旁路双喉喷嘴（BDTN）能够最大限度地提高推力矢量性能，因此与其他流体矢量控制相比具有优势。在本研究中，我们进行了数值模拟，以分析具有三种不同喷嘴配置的飞机发动机的流动特性和性能参数。我们选择了具有代表性的 F100 发动机的喷嘴作为几何模型，以测试 BDTN 所获得的效率。本次研究表明，在真实几何喷嘴上实施旁通通道对矢量模式下的推力矢量性能没有显著影响。虽然真实几何方案具有较高的推力和排出系数，但较小的空腔长度导致了较低的矢量角。根据 BDTN 配置修改实际几何喷嘴可显著提高推力矢量性能。然而，修改后的几何方案中的 V 形旁路通道流在喷嘴中造成了不必要的总压力损失。本研究考虑了一种利用弧形而非 V 形旁路通道的几何方案，发现这种方案能将压力损失降至最低。推力系数和排出系数分别增加了 2% 和 3.5%。在改进的几何方案下，推力矢量角减少了 6%。在三种几何方案中，实际几何方案的推力矢量性能可忽略不计，而修改后和改进后的几何方案在不大幅改变发动机状态的情况下提高了推力矢量性能。
{"title":"Effect of Bypass Duct On the Thrust Vectoring Performance of Dual Throat Nozzle in a Supersonic Aircraft","authors":"Saadia Afridi, Tariq Amin Khan, Imran Shah, Yasir Ali, M. N. M. Qadri, Wei Li","doi":"10.1115/1.4064608","DOIUrl":"https://doi.org/10.1115/1.4064608","url":null,"abstract":"\u0000 Due to its ability to maximize thrust-vectoring performance, the bypass dual throat nozzle (BDTN) has an advantage over other fluidic vectoring controls. In this study, numerical simulation is performed to analyze the flow characteristics and performance parameters of an aircraft engine with three different nozzle configurations. The nozzle of a representative engine i.e., an F100 engine was selected as a model geometry to test the efficiency obtained by BDTN. The present investigation has shown that implementing a bypass channel on a real geometry nozzle has no significant effects on thrust vectoring performance in vectoring mode. Although the real geometry scheme has a higher thrust and a discharge coefficient, the smaller cavity length resulted in lower vectoring angles. Modifying the real geometry nozzle according to the BDTN configuration significantly improved the thrust vectoring performance. However, the V-shaped bypass passage flow in the modified geometry scheme imposed unnecessary total pressure losses in the nozzle. A geometry scheme that utilized an arc-shaped rather than a V-shaped bypass passage is considered in this research and found to present minimize pressure losses. A total increase of 2% and 3.5% is hereby reported, for thrust and discharge coefficients respectively. A decrease of 6% is reported in the thrust vectoring angle under an improved geometrical scheme. Out of three geometries, the real geometry scheme reported negligible thrust vectoring performance, while modified and improved geometry schemes indicated improved thrust vectoring performance without substantially changing the engine states.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"6 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139826806","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}
Christopher Wingel, Nicolas Binder, Yannick Bousquet, J. Boussuge, N. Buffaz, Sébastien Le Guyader
This study is carried out in the context of hot streak flows in high-pressure turbines, for which a correct prediction of the temperature evolution is required. The present work particularly focuses on the turbulence anisotropy analysis of a swirled hot streak flow in a bent channel representative of a NGV passage of a high-pressure turbine. LES are conducted with the in-house solver IC3 in order to measure and characterise the anisotropy of turbulence. Moreover, to evaluate turbulence modelling, steady simulations of the bent channel are performed with the ELSA software, which solves the RANS equations. LES is firstly used to complete a TKE budget that enables to understand the energetic transfers associated with turbulence. This budget reveals two distinct zones where turbulence activity is impacted when the curvature is reached. The analysis of the anisotropy of turbulence based on two metrics highlights a misalignment of the Reynolds stress tensor and the mean strain-rate tensor (Schmitt's criterion), and a strong anisotropy developing inside the bent duct (Lumley's analysis) that may cause the failure of the classical RANS turbulence models based on Boussinesq's hypothesis. To check this hypothesis, RANS is positioned against LES with different turbulence models that accounts or not for the anisotropy of turbulence. Both turbulence activity (TKE budgets, Lumley's analysis) and aerothermal fields (radial distributions) are compared. Results show that EARSM models enable to better account for the anisotropy of turbulence, which in turn promote a better prediction of temperature, both in terms of intensity and trajectory.
{"title":"Analysis and Modelling of Turbulence Anisotropy of a Swirled Hot Streak Flow","authors":"Christopher Wingel, Nicolas Binder, Yannick Bousquet, J. Boussuge, N. Buffaz, Sébastien Le Guyader","doi":"10.1115/1.4064609","DOIUrl":"https://doi.org/10.1115/1.4064609","url":null,"abstract":"\u0000 This study is carried out in the context of hot streak flows in high-pressure turbines, for which a correct prediction of the temperature evolution is required. The present work particularly focuses on the turbulence anisotropy analysis of a swirled hot streak flow in a bent channel representative of a NGV passage of a high-pressure turbine. LES are conducted with the in-house solver IC3 in order to measure and characterise the anisotropy of turbulence. Moreover, to evaluate turbulence modelling, steady simulations of the bent channel are performed with the ELSA software, which solves the RANS equations. LES is firstly used to complete a TKE budget that enables to understand the energetic transfers associated with turbulence. This budget reveals two distinct zones where turbulence activity is impacted when the curvature is reached. The analysis of the anisotropy of turbulence based on two metrics highlights a misalignment of the Reynolds stress tensor and the mean strain-rate tensor (Schmitt's criterion), and a strong anisotropy developing inside the bent duct (Lumley's analysis) that may cause the failure of the classical RANS turbulence models based on Boussinesq's hypothesis. To check this hypothesis, RANS is positioned against LES with different turbulence models that accounts or not for the anisotropy of turbulence. Both turbulence activity (TKE budgets, Lumley's analysis) and aerothermal fields (radial distributions) are compared. Results show that EARSM models enable to better account for the anisotropy of turbulence, which in turn promote a better prediction of temperature, both in terms of intensity and trajectory.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"63 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139827103","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}
Centrifugal pumps with guide vanes are widely used in pump as turbine, energy storage pump station and water diversion project. In this work, a theoretical prediction model based on fluid governing equation and Oseen vortex model is proposed to predict the velocity moment downstream the impeller of centrifugal pump. Then, an optimization design method is established to optimize the impeller of centrifugal pump with guide vanes. A centrifugal pump with specific speed of 127 is used to validate the theoretical prediction model, results of velocity moment show that the deviation between predicted and simulated results is below 0.5% in average. Finally, the optimization design method is applied, results show that the average efficiency of optimal pump under the working conditions is 1.04% higher than that of baseline pump, which validates the reliability of proposed optimization method by theoretical prediction based on Oseen vortex. Analysis on velocity distribution and turbulence eddy dissipation shows that the optimization design method based on Oseen vortex can effectively improve the flow pattern and pump performance.
{"title":"Design Method for Impeller of Centrifugal Pump with Guide Vanes Based On Oseen Vortex","authors":"Yangping Lu, Ming Liu, Lei Tan, Demin Liu","doi":"10.1115/1.4064607","DOIUrl":"https://doi.org/10.1115/1.4064607","url":null,"abstract":"\u0000 Centrifugal pumps with guide vanes are widely used in pump as turbine, energy storage pump station and water diversion project. In this work, a theoretical prediction model based on fluid governing equation and Oseen vortex model is proposed to predict the velocity moment downstream the impeller of centrifugal pump. Then, an optimization design method is established to optimize the impeller of centrifugal pump with guide vanes. A centrifugal pump with specific speed of 127 is used to validate the theoretical prediction model, results of velocity moment show that the deviation between predicted and simulated results is below 0.5% in average. Finally, the optimization design method is applied, results show that the average efficiency of optimal pump under the working conditions is 1.04% higher than that of baseline pump, which validates the reliability of proposed optimization method by theoretical prediction based on Oseen vortex. Analysis on velocity distribution and turbulence eddy dissipation shows that the optimization design method based on Oseen vortex can effectively improve the flow pattern and pump performance.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"65 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139873415","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}
Christopher Wingel, Nicolas Binder, Yannick Bousquet, J. Boussuge, N. Buffaz, Sébastien Le Guyader
This study is carried out in the context of hot streak flows in high-pressure turbines, for which a correct prediction of the temperature evolution is required. The present work particularly focuses on the turbulence anisotropy analysis of a swirled hot streak flow in a bent channel representative of a NGV passage of a high-pressure turbine. LES are conducted with the in-house solver IC3 in order to measure and characterise the anisotropy of turbulence. Moreover, to evaluate turbulence modelling, steady simulations of the bent channel are performed with the ELSA software, which solves the RANS equations. LES is firstly used to complete a TKE budget that enables to understand the energetic transfers associated with turbulence. This budget reveals two distinct zones where turbulence activity is impacted when the curvature is reached. The analysis of the anisotropy of turbulence based on two metrics highlights a misalignment of the Reynolds stress tensor and the mean strain-rate tensor (Schmitt's criterion), and a strong anisotropy developing inside the bent duct (Lumley's analysis) that may cause the failure of the classical RANS turbulence models based on Boussinesq's hypothesis. To check this hypothesis, RANS is positioned against LES with different turbulence models that accounts or not for the anisotropy of turbulence. Both turbulence activity (TKE budgets, Lumley's analysis) and aerothermal fields (radial distributions) are compared. Results show that EARSM models enable to better account for the anisotropy of turbulence, which in turn promote a better prediction of temperature, both in terms of intensity and trajectory.
{"title":"Analysis and Modelling of Turbulence Anisotropy of a Swirled Hot Streak Flow","authors":"Christopher Wingel, Nicolas Binder, Yannick Bousquet, J. Boussuge, N. Buffaz, Sébastien Le Guyader","doi":"10.1115/1.4064609","DOIUrl":"https://doi.org/10.1115/1.4064609","url":null,"abstract":"\u0000 This study is carried out in the context of hot streak flows in high-pressure turbines, for which a correct prediction of the temperature evolution is required. The present work particularly focuses on the turbulence anisotropy analysis of a swirled hot streak flow in a bent channel representative of a NGV passage of a high-pressure turbine. LES are conducted with the in-house solver IC3 in order to measure and characterise the anisotropy of turbulence. Moreover, to evaluate turbulence modelling, steady simulations of the bent channel are performed with the ELSA software, which solves the RANS equations. LES is firstly used to complete a TKE budget that enables to understand the energetic transfers associated with turbulence. This budget reveals two distinct zones where turbulence activity is impacted when the curvature is reached. The analysis of the anisotropy of turbulence based on two metrics highlights a misalignment of the Reynolds stress tensor and the mean strain-rate tensor (Schmitt's criterion), and a strong anisotropy developing inside the bent duct (Lumley's analysis) that may cause the failure of the classical RANS turbulence models based on Boussinesq's hypothesis. To check this hypothesis, RANS is positioned against LES with different turbulence models that accounts or not for the anisotropy of turbulence. Both turbulence activity (TKE budgets, Lumley's analysis) and aerothermal fields (radial distributions) are compared. Results show that EARSM models enable to better account for the anisotropy of turbulence, which in turn promote a better prediction of temperature, both in terms of intensity and trajectory.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139887105","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}
Saadia Afridi, Tariq Amin Khan, Imran Shah, Yasir Ali, M. N. M. Qadri, Wei Li
Due to its ability to maximize thrust-vectoring performance, the bypass dual throat nozzle (BDTN) has an advantage over other fluidic vectoring controls. In this study, numerical simulation is performed to analyze the flow characteristics and performance parameters of an aircraft engine with three different nozzle configurations. The nozzle of a representative engine i.e., an F100 engine was selected as a model geometry to test the efficiency obtained by BDTN. The present investigation has shown that implementing a bypass channel on a real geometry nozzle has no significant effects on thrust vectoring performance in vectoring mode. Although the real geometry scheme has a higher thrust and a discharge coefficient, the smaller cavity length resulted in lower vectoring angles. Modifying the real geometry nozzle according to the BDTN configuration significantly improved the thrust vectoring performance. However, the V-shaped bypass passage flow in the modified geometry scheme imposed unnecessary total pressure losses in the nozzle. A geometry scheme that utilized an arc-shaped rather than a V-shaped bypass passage is considered in this research and found to present minimize pressure losses. A total increase of 2% and 3.5% is hereby reported, for thrust and discharge coefficients respectively. A decrease of 6% is reported in the thrust vectoring angle under an improved geometrical scheme. Out of three geometries, the real geometry scheme reported negligible thrust vectoring performance, while modified and improved geometry schemes indicated improved thrust vectoring performance without substantially changing the engine states.
旁路双喉喷嘴（BDTN）能够最大限度地提高推力矢量性能，因此与其他流体矢量控制相比具有优势。在本研究中，我们进行了数值模拟，以分析具有三种不同喷嘴配置的飞机发动机的流动特性和性能参数。我们选择了具有代表性的 F100 发动机的喷嘴作为几何模型，以测试 BDTN 所获得的效率。本次研究表明，在真实几何喷嘴上实施旁通通道对矢量模式下的推力矢量性能没有显著影响。虽然真实几何方案具有较高的推力和排出系数，但较小的空腔长度导致了较低的矢量角。根据 BDTN 配置修改实际几何喷嘴可显著提高推力矢量性能。然而，修改后的几何方案中的 V 形旁路通道流在喷嘴中造成了不必要的总压力损失。本研究考虑了一种利用弧形而非 V 形旁路通道的几何方案，发现这种方案能将压力损失降至最低。推力系数和排出系数分别增加了 2% 和 3.5%。在改进的几何方案下，推力矢量角减少了 6%。在三种几何方案中，实际几何方案的推力矢量性能可忽略不计，而修改后和改进后的几何方案在不大幅改变发动机状态的情况下提高了推力矢量性能。
{"title":"Effect of Bypass Duct On the Thrust Vectoring Performance of Dual Throat Nozzle in a Supersonic Aircraft","authors":"Saadia Afridi, Tariq Amin Khan, Imran Shah, Yasir Ali, M. N. M. Qadri, Wei Li","doi":"10.1115/1.4064608","DOIUrl":"https://doi.org/10.1115/1.4064608","url":null,"abstract":"\u0000 Due to its ability to maximize thrust-vectoring performance, the bypass dual throat nozzle (BDTN) has an advantage over other fluidic vectoring controls. In this study, numerical simulation is performed to analyze the flow characteristics and performance parameters of an aircraft engine with three different nozzle configurations. The nozzle of a representative engine i.e., an F100 engine was selected as a model geometry to test the efficiency obtained by BDTN. The present investigation has shown that implementing a bypass channel on a real geometry nozzle has no significant effects on thrust vectoring performance in vectoring mode. Although the real geometry scheme has a higher thrust and a discharge coefficient, the smaller cavity length resulted in lower vectoring angles. Modifying the real geometry nozzle according to the BDTN configuration significantly improved the thrust vectoring performance. However, the V-shaped bypass passage flow in the modified geometry scheme imposed unnecessary total pressure losses in the nozzle. A geometry scheme that utilized an arc-shaped rather than a V-shaped bypass passage is considered in this research and found to present minimize pressure losses. A total increase of 2% and 3.5% is hereby reported, for thrust and discharge coefficients respectively. A decrease of 6% is reported in the thrust vectoring angle under an improved geometrical scheme. Out of three geometries, the real geometry scheme reported negligible thrust vectoring performance, while modified and improved geometry schemes indicated improved thrust vectoring performance without substantially changing the engine states.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139886715","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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