Previous studies showed that an axisymmetric hub-initiated disturbance defined as partial surge may initiate the stall of a transonic compressor; to reveal the instability evolution under full-span incompressible flow...Previous studies showed that an axisymmetric hub-initiated disturbance defined as partial surge may initiate the stall of a transonic compressor; to reveal the instability evolution under full-span incompressible flow for different levels of hub loading and B parameter, an experimental investigation is conducted on a single-stage low-speed compressor. Experimental results show that under a uniform inflow condition without inlet flow distortion, a modal-type stall inception dominates in this low-speed compressor. When an inlet screen introducing hub distortion is used to increase the hub loading, a compressor stall is initiated by a modal wave, but large disturbances are present in the hub region before the compressor stall, which become stronger as the hub loading increases. Under high hub loading and large B parameter（implemented by adding hub distortion through an inlet screen and enlarging the outlet plenum volume, respectively）, a compressor stall is triggered by an axisymmetric hub-initiated disturbance, which is much different from the modal-like disturbances. The beginning of this axisymmetric disturbance may be captured over 800 rotor revolutions prior to the onset of stall, and the amplitude grows with time. The disturbance is hub-initiated because the disturbance signal at the hub is detected much earlier than that at the tip; meanwhile, the frequency of this axisymmetric disturbance changes with the length of the inlet duct. The characteristics of instability evolution in the low-speed compressor are also compared with those in a transonic compressor.展开更多
With the aim of deepening the understanding of high-speed compressor cascade flow,this paper reports an experimental study on NACA-65 K48 compressor cascade with high subsonic inlet flow.With the increase of passage p...With the aim of deepening the understanding of high-speed compressor cascade flow,this paper reports an experimental study on NACA-65 K48 compressor cascade with high subsonic inlet flow.With the increase of passage pressurizing ability, endwall boundary layer behavior is deteriorated, and the transition zone is extended from suction surface to the endwall as the adverse pressure gradient increases.Cross flow from endwall to midspan, mixing of corner boundary layer and the main stream, and reversal flow on the suction surface are caused by corner separation vortex structures.Passage vortex is the main corner separation vortex.During its movement downstream, the size grows bigger while the rotating direction changes, forming a limiting circle.With higher incidence, corner separation is further deteriorated, leading to higher flow loss.Meanwhile, corner separation structure, flow mixing characteristics and flow loss distribution vary a lot with the change of incidence.Compared with low aspect-ratio model, corner separation of high aspect-ratio model moves away from the endwall and is more sufficiently developed downstream the cascade.Results obtained present details of high-speed compressor cascade flow,which is rare in the relating research fields and is beneficial to mechanism analysis, aerodynamic optimization and flow control design.展开更多
电动汽车具有可实现节能减排的特点,开发全球变暖潜能值更低的制冷剂应用于电动汽车制冷系统是车用空调的重要研究方向。搭建了一台R290电动汽车压缩机制冷系统性能测试装置,研究变压缩机转速、蒸发温度和冷凝温度对R290制冷系统中电动...电动汽车具有可实现节能减排的特点,开发全球变暖潜能值更低的制冷剂应用于电动汽车制冷系统是车用空调的重要研究方向。搭建了一台R290电动汽车压缩机制冷系统性能测试装置,研究变压缩机转速、蒸发温度和冷凝温度对R290制冷系统中电动汽车压缩机的性能的影响。结果表明:压缩机的制冷系数(coefficient of performance,COP)和等熵效率随压缩机转速和蒸发温度上升而增大,而与冷凝温度负相关;压缩机转速超过3 000 r/min时,COP和等熵效率缓慢增加并趋于平缓,高压缩机转速及压比造成压缩机的等熵效率下降;压缩机的制冷量随着压缩机转速和蒸发温度的增加而增大,而与冷凝温度负相关;相同工况下,R290的压缩机耗功大,但其制冷量和COP均优于R134a,且R290的充注量和排气温度更小。因此,R290可作为R134a在电动汽车热管理系统的替代工质。展开更多
This paper mainly deals with dynamic analysis of rotor-bearing system in a centrifugal compressor. A finite element model of the rotor-bearing system has been developed. The considered factors of the model include the...This paper mainly deals with dynamic analysis of rotor-bearing system in a centrifugal compressor. A finite element model of the rotor-bearing system has been developed. The considered factors of the model include the rotary inertia of solid elements, stiffness and damping of hydrodynamic bearing. In the calculating, ANSYS software was used. Both calculated and measured results are in good agreement.展开更多
基金the supports of the National Natural Science Foundation of China (Nos.51636001 and 51706008)Aeronautics Power Foundation of China (No.6141B090315)China Postdoctoral Science Foundation (No.2017M610742)
文摘Previous studies showed that an axisymmetric hub-initiated disturbance defined as partial surge may initiate the stall of a transonic compressor; to reveal the instability evolution under full-span incompressible flow for different levels of hub loading and B parameter, an experimental investigation is conducted on a single-stage low-speed compressor. Experimental results show that under a uniform inflow condition without inlet flow distortion, a modal-type stall inception dominates in this low-speed compressor. When an inlet screen introducing hub distortion is used to increase the hub loading, a compressor stall is initiated by a modal wave, but large disturbances are present in the hub region before the compressor stall, which become stronger as the hub loading increases. Under high hub loading and large B parameter（implemented by adding hub distortion through an inlet screen and enlarging the outlet plenum volume, respectively）, a compressor stall is triggered by an axisymmetric hub-initiated disturbance, which is much different from the modal-like disturbances. The beginning of this axisymmetric disturbance may be captured over 800 rotor revolutions prior to the onset of stall, and the amplitude grows with time. The disturbance is hub-initiated because the disturbance signal at the hub is detected much earlier than that at the tip; meanwhile, the frequency of this axisymmetric disturbance changes with the length of the inlet duct. The characteristics of instability evolution in the low-speed compressor are also compared with those in a transonic compressor.
基金supported by the National Natural Science Foundation of China (Nos.51336011, 50906100)the Science Foundation for the Author of National Excellent Doctoral Dissertation of China (No.201172)China Scholarship Council
文摘With the aim of deepening the understanding of high-speed compressor cascade flow,this paper reports an experimental study on NACA-65 K48 compressor cascade with high subsonic inlet flow.With the increase of passage pressurizing ability, endwall boundary layer behavior is deteriorated, and the transition zone is extended from suction surface to the endwall as the adverse pressure gradient increases.Cross flow from endwall to midspan, mixing of corner boundary layer and the main stream, and reversal flow on the suction surface are caused by corner separation vortex structures.Passage vortex is the main corner separation vortex.During its movement downstream, the size grows bigger while the rotating direction changes, forming a limiting circle.With higher incidence, corner separation is further deteriorated, leading to higher flow loss.Meanwhile, corner separation structure, flow mixing characteristics and flow loss distribution vary a lot with the change of incidence.Compared with low aspect-ratio model, corner separation of high aspect-ratio model moves away from the endwall and is more sufficiently developed downstream the cascade.Results obtained present details of high-speed compressor cascade flow,which is rare in the relating research fields and is beneficial to mechanism analysis, aerodynamic optimization and flow control design.
文摘电动汽车具有可实现节能减排的特点,开发全球变暖潜能值更低的制冷剂应用于电动汽车制冷系统是车用空调的重要研究方向。搭建了一台R290电动汽车压缩机制冷系统性能测试装置,研究变压缩机转速、蒸发温度和冷凝温度对R290制冷系统中电动汽车压缩机的性能的影响。结果表明:压缩机的制冷系数(coefficient of performance,COP)和等熵效率随压缩机转速和蒸发温度上升而增大,而与冷凝温度负相关;压缩机转速超过3 000 r/min时,COP和等熵效率缓慢增加并趋于平缓,高压缩机转速及压比造成压缩机的等熵效率下降;压缩机的制冷量随着压缩机转速和蒸发温度的增加而增大,而与冷凝温度负相关;相同工况下,R290的压缩机耗功大,但其制冷量和COP均优于R134a,且R290的充注量和排气温度更小。因此,R290可作为R134a在电动汽车热管理系统的替代工质。
基金the Youth Foundation of Shanghai Municipal Commission of Education(200QN72 )
文摘This paper mainly deals with dynamic analysis of rotor-bearing system in a centrifugal compressor. A finite element model of the rotor-bearing system has been developed. The considered factors of the model include the rotary inertia of solid elements, stiffness and damping of hydrodynamic bearing. In the calculating, ANSYS software was used. Both calculated and measured results are in good agreement.
