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| 1 | Control of Corner Separation by Optimized Slot Configuration in a Linear Compressor Cascade显示文摘为控制压气机叶片吸力面与端壁处所形成的三维角区分离,本文在叶根处引入了从压力面到吸力面的槽道来控制角区分离流动。基于利用优化算法对叶根处槽道几何的优化结果,本文通过数值模拟和实验来分析槽道在不同进口攻角下对角区分离的控制效果。本文通过对比原始和开槽叶栅中总压损失、静压升和三维角区分离特征表明叶根处引入的槽道对角区分离有明显的控制效果。 | Jinjing Sun Yangwei Liu Lipeng Lu Xavier OTTAVY | 2016 | 风机技术2016，58，6： | 4 |
| 2 | High-fidelity numerical simulation of unsteady cavitating flow around a hydrofoil显示文摘Cavitation is a widespread and detrimental phenomenon in hydraulic machinery, therefore, it requires to be accurately predicted. In this study, large eddy simulation (LES), scale-adaptive simulation (SAS) and grid-adaptive simulation (GAS) are employed to investigate the unsteady cavitating flow around a NACA0009 hydrofoil. The prediction accuracy of GAS, SAS, both using the shear-stress transport (SST) k — ω model as baseline turbulence model, is validated by comparing with experimental and LES results. The cavity behaviors and turbulence fields are analyzed systematically. Results show that the GAS gives a more reasonable turbulent viscosity and accurately predicts the periodic evolution of typical vortical structures of cavitating flow, such as tip leakage vortex cavitation, tip separation vortex cavitation, leading-edge cavitation, and trailing-edge vortex. The time-averaged cavity volume, volume fluctuation amplitude, and characteristic frequencies of cavities predicted by the GAS are very closed to the LES, while the SAS fails to accurately capture these cavity characteristics. Furthermore, the local trace criterion is applied to extract the vortical structures and to analyze the swirling patterns of the tip leakage vortex. Multi-scale vortical structures in LES are well identified by local trace criterion. The prediction accuracy of the SAS method for small-scale vortical structures, such as the vortex shedding on the suction side and the vortex rope around the tip leakage vortex, is obviously insufficient, while the GAS has a higher accuracy in predicting vortex shedding. The tip leakage vortex and induced vortex extracted from GAS are also closer to that of LES in both swirling patterns and scale. | Nan Xie Yu-meng Tang Yang-wei Liu | 2023 | Journal of Hydrodynamics2023，35，1： | 2 |
| 3 | Pitch control strategy before the rated power for variable speed wind turbines at high altitudes显示文摘The wind turbines in the world's highest wind farm with an altitude of over 4 000 m in Naqu county of China were put into operation in 2014.Compared with the wind turbines at lower altitudes,the rated wind speed of these wind turbines are much larger,and the corresponding tip-speed ratio at the rated power reduces significantly due to the lower air density.Hence,the power coefficient at the point of the rated power is decreased to a rather low level.To improve the performance of the wind turbines at very high altitudes,this paper proposes a new pitch control strategy for variable speed wind turbines at the constant-speed phase,especially at the rated-speed phase before the rated power is reached.It is shown that the new pitch control strategy works very well for the wind farms at very high altitude and with low air density,with the catch of the wind energy enhaneed and the aerodynamic loads significantly reduced. | Ming-wei Ge Wei-ming Ke Hong-xia Chen | 2019 | Journal of Hydrodynamics2019，31，2： | 1 |
| 4 | A modified VLES model for simulation of rotating separation flow in axial flow rotating machinery显示文摘The internal flow in an axial flow rotating machinery is affected by the rotating characteristics, often accompanied by a strong rotating separation under small flow conditions. At present, the very large eddy simulation (VLES) model commonly used for the separation flow simulation still has certain limitations in simulating such rotating separation flow: (1) The Reynolds stress level is overestimated in the near-wall region. (2) The influence of the rotating effect cannot be effectively considered. The above two limitations affect the simulation accuracy of the VLES model for the rotating separation flow under small flow conditions in the axial flow rotating machinery. The objective of this paper is to provide a new hybrid unsteady Reynolds average Navier-Stokes/large eddy simulation (URANS/LES) model suitable for the simulation of the rotating separation flow in an axial flow rotating machinery. Compared with the original VLES method, the modifications are as follows: (1) A Reynolds stress damping function in the near-wall region is introduced to reduce the overestimation of the Reynolds stress caused by the near-wall Reynolds average Navier-Stokes (RANS) behavior of the VLES model. (2) A control function driven by the vortex is introduced to reflect the influence of the rotating effect. Three typical cases are used to verify the calculation accuracy of the modified model. It is shown that the modified model can capture more turbulent vortices based on the URANS grids, and the prediction accuracy of the rotating separation flow is effectively improved. Compared with the original VLES model, the modified model can accurately predict the head change in the hump region of the axial flow pump. | Hao-ru Zhao Fu-jun Wang Chao-yue Wang Chang-liang Ye Zhi-feng Yao Qiang Zhong | 2022 | Journal of Hydrodynamics2022，34，4： | 1 |
| 5 | 不同间隙大小轴流压气机转子叶尖泄漏非定常流动的DDES研究(英文)显示文摘叶尖泄漏流动对航空发动机的压气机性能有很大的影响,对其进行准确的数值模拟十分重要。延迟脱落涡模拟(DDES)方法在保证计算准确性的同时节省了计算资源。本文针对不同间隙大小和不同工况对大尺寸低速轴流压气机转子进行了DDES 模拟。将时均结果与瞬时结果进行了比较,分析了不同叶尖尺寸下流动的非定常性。然后利用LUMLEY 三角形分析了叶尖泄漏流动的雷诺应力各向异性。各向异性沿叶尖泄漏涡向下游发展方向变化。小间隙情况下各向异性较弱,这是由于小间隙情况下流动更加稳定。最后,利用快速傅里叶变换(FFT)分析了泄漏涡核心的速度脉动频谱,讨论了泄漏流动的非定常性。 | 钟路阳 柳阳威 陆利蓬 | 2019 | 风机技术2019，61，2： | 0 |
| 6 | A novel Omega-driven dynamic PANS model显示文摘A novel Omega(Ω)-driven dynamic partially-averaged Navier-Stokes(PANS)model is proposed in this paper.The ratio of the modeled-to-total turbulent kinetic energies fk is dynamically adjusted by the rigid vorticity ratio(the ratio of the rigid vorticity to the total vorticity),the key parameter of the Ω vortex identification method.Three classical flow cases with rotation and curvature are used to test the model.The results show that the turbulent viscosity is effectively adjusted by the new dynamic fk and the LES-like mode is activated,which can help the revelation of more turbulence information and improve the prediction accuracy.The new PANS model does not contain any explicit dependency on the grid size and enjoys good adaptability to the flow fields,and can be used for efficient engineering computations of the turbulent flows in the hydraulic machinery. | Chao-yue Wang Fu-jun Wang Ben-hong Wang Yuan Tang Hao-ru Zhao | 2020 | Journal of Hydrodynamics2020，32，4： | 0 |
| 7 | Computation method and control strategy of rotating separation flows in hydraulic machinery显示文摘Rotating separation flow(RSF)in hydraulic machinery is characterized by the large flow separations and complex vortical structures induced by the effects of strong rotation,large curvature and multiple wall surfaces,and conducting efficient engineering computation and putting forward effective control strategy for the RSF are important topics in the inner flow theory.To meet these engineering requirements,the studies on computational method and control strategy of the RSF are conducted in this paper.In terms of the computational method,the time-scale-driven(TSD)hybrid unsteady Reynolds-averaged Navier-Stokes/large eddy simulation(URANS/LES)modelling strategy is clarified,and an adaptive TSD hybrid model is established based on the RSF characteristics in hydraulic machinery,thereby avoiding the problem of non-monotonic grid convergence and improving the robustness.Besides,a novel vortex-feature-driven idea suitable for the RSF is further developed inspired by it.In terms of the control strategy,the secondary flow generation mechanism in a rotor domain is revealed,and the relationship between natural secondary flows and blade loading distributions is grasped.On the basis of it,an active control strategy with general significance is proposed,and a general alternate loading technique(GALT)is established.Both aspects can provide generalized paradigms with expandable potential,which are of benefit to the efficient computation and effective control of the RSF in hydraulic machinery. | Chao-yue Wang Fu-jun Wang Hao Wang Hao-ru Zhao Zhi-feng Yao Ruo-fu Xiao | 2022 | Journal of Hydrodynamics2022，34，6： | 0 |
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