The end-wall shaping effects of the guide blade in the steam turbine stages are studied.The research of the end-wall shaping effects on turbine efficiency applies CFD numerical simulations and the measurement of strai...The end-wall shaping effects of the guide blade in the steam turbine stages are studied.The research of the end-wall shaping effects on turbine efficiency applies CFD numerical simulations and the measurement of straight blade cascades in the wind tunnel.The final stage of research activities includes the experimental verification of the findings in an experimental steam turbine.As the findings are interesting in terms of efficiency,a series of 3-D numerical simulations are executed.These demonstrate the certain improvement when the shaping is used,especially in the blade tip area.The steam turbine is used to measure the shaping effects on both sides（bilateral shaping）as well as only in the blade tip area.The process indicates the efficiency improvement on the blade tip shaping.However,this occurs only in partial admission.On the other hand,there is a drop in efficiency compared with blades with straight end-walls.展开更多
To overcome the limitations posed by three-dimensional corner separation,this paper proposes a novel flow control technology known as passive End-Wall(EW)self-adaptive jet.Two single EW slotted schemes(EWS1 and EWS2),...To overcome the limitations posed by three-dimensional corner separation,this paper proposes a novel flow control technology known as passive End-Wall(EW)self-adaptive jet.Two single EW slotted schemes(EWS1 and EWS2),alongside a combined(COM)scheme featuring double EW slots,were investigated.The results reveal that the EW slot,driven by pressure differentials between the pressure and suction sides,can generate an adaptive jet with escalating velocity as the operational load increases.This high-speed jet effectively re-excites the local low-energy fluid,thereby mitigating the corner separation.Notably,the EWS1 slot,positioned near the blade leading edge,exhibits relatively low jet velocities at negative incidence angles,causing jet separation and exacerbating the corner separation.Besides,the EWS2 slot is close to the blade trailing edge,resulting in massive low-energy fluid accumulating and separating before the slot outlet at positive incidence angles.In contrast,the COM scheme emerges as the most effective solution for comprehensive corner separation control.It can significantly reduce the total pressure loss and improve the static pressure coefficient for the ORI blade at 0°-4° incidence angles,while causing minimal negative impact on the aerodynamic performance at negative incidence angles.Therefore,the corner stall is delayed,and the available incidence angle range is broadened from -10°--2°to -10°-4°.This holds substantial promise for advancing the aerodynamic performance,operational stability,and load capacity of future highly loaded compressors.展开更多
This paper deals with the application of a non-axisyrmnetric hub end-wall on the stator of a single stage high subsonic axial-flow compressor. In order to obtain a state-of-the-art stator non-axisymmetric hub end-wall...This paper deals with the application of a non-axisyrmnetric hub end-wall on the stator of a single stage high subsonic axial-flow compressor. In order to obtain a state-of-the-art stator non-axisymmetric hub end-wall con- figuration fulfilling the requirements for higher efficiency and total pressure ratio, an automated multi-objective optimizer was used, in conjunction with 3D-RANS-flow simulations. For the purpose of quantifying the effect of the optimal stator non axis-symmetric hub contouring on the compressor performance and its effects on the sub- sonic axial-flow compressor stator end-wall flow field structure, the coupled flow of the compressor stage with the baseline, axisymmetric and the non-axisynunetric stator hub end-wall was simulated with a state-of-the- art multi-block flow 3D CFD solver. Based on the CFD simulations, the optimal compressor hub end-wall con- figuration is expected to increase the peak efficiency by approximately 2.04 points and a slight increase of the to- tal pressure ratio. Detailed analyses of the numerical flow visualization at the hub have uncovered the different hub flow topologies between the cases with axisymmetric and non-axisymmetric hub end-walls. It was found that that the primary performance enhancement afforded by the non-axisymmelric hub end-wall is a result of the end-wall flow structure modification. Compared to the smooth wall case, the non-axisymmetric hub end-wall can reduce the formation and development of in-passage secondary flow by aerodynamic loading redistribution.展开更多
Based on the eigenfunction expansion technique, the wave generation by a piston wave maker in a wave flume with a partially reflecting end-wall is studied. The corresponding velocity potential and wave elevation in th...Based on the eigenfunction expansion technique, the wave generation by a piston wave maker in a wave flume with a partially reflecting end-wall is studied. The corresponding velocity potential and wave elevation in the flume are obtained. The present analytical solution is verified by the numerical results obtained from a time-domain higher-order boundary element method in a closed flume. Numerical experiments are further carried out to study the difference between the partial/full reflection boundary and the transmission boundary and the effects of the reflection coefficient and the motion period of the wave maker on the wave height. Meanwhile, the natural frequency of the wave flume can be obtained from the analytical expression. The resonance occurs when the motion frequency is equal to the natural frequency. Even the partial reflection of the end-wall in the wave flume experiments has a great influence on the wave height, therefore, inaccurate measurements would be resulted in long-time simulations, especially when the wave frequency approaches the wave flume natural frequency. The present study can serve as a guidance for the physical experiment in wave flumes.展开更多
对高速动车组端墙异常振动噪声进行了测试和数据分析,掌握了故障信号特征。通过对风挡区域气动噪声的仿真和线路试验数据的分析,研究异常振动噪声的来源和传播途径,分析故障产生机理,并分别从降低声源的风挡结构优化和传递路径控制的粒...对高速动车组端墙异常振动噪声进行了测试和数据分析,掌握了故障信号特征。通过对风挡区域气动噪声的仿真和线路试验数据的分析,研究异常振动噪声的来源和传播途径,分析故障产生机理,并分别从降低声源的风挡结构优化和传递路径控制的粒子阻尼减振两方面提出了解决方案。线路试验结果表明,两种方案均对端墙异常振动噪声有较好的抑制作用,高速动车组在350 km/h运行时,风挡安装扰流板后,40 Hz频带噪声级降低5 d B(A),总噪声级降低3.5 d B(A);端墙安装粒子阻尼器后,40 Hz频带噪声级降低4.3 d B(A),总噪声级降低2.4 d B(A),铝合金端墙减振率达43.1%。展开更多
基金the Ministry of Industry and Trade of the Czech Republic for the financial support of Grant No.FT-TA2/037
文摘The end-wall shaping effects of the guide blade in the steam turbine stages are studied.The research of the end-wall shaping effects on turbine efficiency applies CFD numerical simulations and the measurement of straight blade cascades in the wind tunnel.The final stage of research activities includes the experimental verification of the findings in an experimental steam turbine.As the findings are interesting in terms of efficiency,a series of 3-D numerical simulations are executed.These demonstrate the certain improvement when the shaping is used,especially in the blade tip area.The steam turbine is used to measure the shaping effects on both sides（bilateral shaping）as well as only in the blade tip area.The process indicates the efficiency improvement on the blade tip shaping.However,this occurs only in partial admission.On the other hand,there is a drop in efficiency compared with blades with straight end-walls.
基金sponsored by the National Natural Science Foundation of China(No.52106057)the National Major Science and Technology Projects of China(No.2017-Ⅱ-0001-0013)+2 种基金Fundamental Research Funds for the Central Universities of China(No.D5000210483)the Foundation of State Level Key Laboratory of Airfoil and Cascade Aerodynamics of China(Nos.D5150210006 and D5050210015)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University of China(No.CX2023012).
文摘To overcome the limitations posed by three-dimensional corner separation,this paper proposes a novel flow control technology known as passive End-Wall(EW)self-adaptive jet.Two single EW slotted schemes(EWS1 and EWS2),alongside a combined(COM)scheme featuring double EW slots,were investigated.The results reveal that the EW slot,driven by pressure differentials between the pressure and suction sides,can generate an adaptive jet with escalating velocity as the operational load increases.This high-speed jet effectively re-excites the local low-energy fluid,thereby mitigating the corner separation.Notably,the EWS1 slot,positioned near the blade leading edge,exhibits relatively low jet velocities at negative incidence angles,causing jet separation and exacerbating the corner separation.Besides,the EWS2 slot is close to the blade trailing edge,resulting in massive low-energy fluid accumulating and separating before the slot outlet at positive incidence angles.In contrast,the COM scheme emerges as the most effective solution for comprehensive corner separation control.It can significantly reduce the total pressure loss and improve the static pressure coefficient for the ORI blade at 0°-4° incidence angles,while causing minimal negative impact on the aerodynamic performance at negative incidence angles.Therefore,the corner stall is delayed,and the available incidence angle range is broadened from -10°--2°to -10°-4°.This holds substantial promise for advancing the aerodynamic performance,operational stability,and load capacity of future highly loaded compressors.
基金Financial support for the work presented is provided by National Natural Science Foundation of China(Project No:51176187)
文摘This paper deals with the application of a non-axisyrmnetric hub end-wall on the stator of a single stage high subsonic axial-flow compressor. In order to obtain a state-of-the-art stator non-axisymmetric hub end-wall con- figuration fulfilling the requirements for higher efficiency and total pressure ratio, an automated multi-objective optimizer was used, in conjunction with 3D-RANS-flow simulations. For the purpose of quantifying the effect of the optimal stator non axis-symmetric hub contouring on the compressor performance and its effects on the sub- sonic axial-flow compressor stator end-wall flow field structure, the coupled flow of the compressor stage with the baseline, axisymmetric and the non-axisynunetric stator hub end-wall was simulated with a state-of-the- art multi-block flow 3D CFD solver. Based on the CFD simulations, the optimal compressor hub end-wall con- figuration is expected to increase the peak efficiency by approximately 2.04 points and a slight increase of the to- tal pressure ratio. Detailed analyses of the numerical flow visualization at the hub have uncovered the different hub flow topologies between the cases with axisymmetric and non-axisymmetric hub end-walls. It was found that that the primary performance enhancement afforded by the non-axisymmelric hub end-wall is a result of the end-wall flow structure modification. Compared to the smooth wall case, the non-axisymmetric hub end-wall can reduce the formation and development of in-passage secondary flow by aerodynamic loading redistribution.
基金supported by the Open Fund of Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering (Grant No.2009491611)the National Natural Science Foundation of China(Grant Nos.50709005,10772040 and 50921001)the Major National Science and Technology Projects of China(Grant No.2008ZX05026-02)
文摘Based on the eigenfunction expansion technique, the wave generation by a piston wave maker in a wave flume with a partially reflecting end-wall is studied. The corresponding velocity potential and wave elevation in the flume are obtained. The present analytical solution is verified by the numerical results obtained from a time-domain higher-order boundary element method in a closed flume. Numerical experiments are further carried out to study the difference between the partial/full reflection boundary and the transmission boundary and the effects of the reflection coefficient and the motion period of the wave maker on the wave height. Meanwhile, the natural frequency of the wave flume can be obtained from the analytical expression. The resonance occurs when the motion frequency is equal to the natural frequency. Even the partial reflection of the end-wall in the wave flume experiments has a great influence on the wave height, therefore, inaccurate measurements would be resulted in long-time simulations, especially when the wave frequency approaches the wave flume natural frequency. The present study can serve as a guidance for the physical experiment in wave flumes.
文摘对高速动车组端墙异常振动噪声进行了测试和数据分析,掌握了故障信号特征。通过对风挡区域气动噪声的仿真和线路试验数据的分析,研究异常振动噪声的来源和传播途径,分析故障产生机理,并分别从降低声源的风挡结构优化和传递路径控制的粒子阻尼减振两方面提出了解决方案。线路试验结果表明,两种方案均对端墙异常振动噪声有较好的抑制作用,高速动车组在350 km/h运行时,风挡安装扰流板后,40 Hz频带噪声级降低5 d B(A),总噪声级降低3.5 d B(A);端墙安装粒子阻尼器后,40 Hz频带噪声级降低4.3 d B(A),总噪声级降低2.4 d B(A),铝合金端墙减振率达43.1%。
