This research investigates the use of single dielectric barrier discharge(SDBD) actuators for energizing the tip leakage flow to suppress rotating stall inception and extend the stable operating range of a low speed a...This research investigates the use of single dielectric barrier discharge(SDBD) actuators for energizing the tip leakage flow to suppress rotating stall inception and extend the stable operating range of a low speed axial compressor with a single rotor.The jet induced by the plasma actuator adds momentum to the flow in the tip region and has a significant impact on the tip-gap flow.Experiments are carried out on a low speed axial compressor with a single rotor.The static pressure is measured at both the rotor inlet and outlet.The flow coefficient and pressure rise coefficient are calculated.Then the characteristic line is acquired to show the overall performance of the compressor.With unsteady plasma actuation of 18kV and 60W the compressor stability range improvement is realized at rotor speed of 1500 r/min – 2400 r/min.展开更多
A novel vortex identification method for the visualization of the flow field is used for the study of the stall process of a transonic compressor.The parameter η4,which is one of the five invariants formed by the sta...A novel vortex identification method for the visualization of the flow field is used for the study of the stall process of a transonic compressor.The parameter η4,which is one of the five invariants formed by the stain rate and vorticity tensors from the theory of modern rational mechanics,is found to have good ability to identify vortex stretching and vortex relaxation/breakdown processes,is introduced here to identify the tip leakage vortices.Compare with former generally used DPH(dynamic pressure head) contour,the new method reveals much more flow details which may advance our understanding of the compressor behaviors.The Vortices details are revealed in both peak efficiency and near stall condition.A possible stall process is also suggested based on the vortices analysis.The tip leakage flow from mid-chord,besides leading edge leakage flow,is also considered to play an important role in the stall process.展开更多
Unsteady flows and rotating stall of a low-speed centrifugal compressor are investigated by measuring vaneless diffuser wall static pressure fluctuation and internal flow fields at different small flow fluxes. During ...Unsteady flows and rotating stall of a low-speed centrifugal compressor are investigated by measuring vaneless diffuser wall static pressure fluctuation and internal flow fields at different small flow fluxes. During the experiment, firstly the real time static pressure fluctuations on the vaneless diffuser shroud at different circumferential and radial position were acquired by high-frequency dynamic pressure transducers. Discrete Fourier transformation analysis and cross-correlation analysis were applied to the experimental results to ascertain the rotating stall beginning operation conditions and stall cells numbers and rotating speed. Secondly, the vaneless diffuser inlet flow angle distribution along diffuser width direction was acquired by single hotwire, which was compared with SENOO＇s analysis results. At last, the internal flow fields of the centrifugal compressor were investigated with a particle image velocimetry （PIV） system at different small flow fluxes. The flow field development of vaneless diffuser and blade flow passage are given at rotating stall conditions. The experiments enrich the understanding of rotating stall flow phenomenon of the low-speed centrifugal compressor and provide full experiment data for designing high performance centrifugal compressor.展开更多
A numerical methodology for investigating compressor instabilities in a multistage environment is presented. The method is based on a stage-by-stage dynamic compression model and considers air compressibility explicit...A numerical methodology for investigating compressor instabilities in a multistage environment is presented. The method is based on a stage-by-stage dynamic compression model and considers air compressibility explicitly throughout the compressor. It involves discretizing the compression system into distinct elements and a use of the local elemental characteristic of mean performance. The models are presented in both nonlinear and linearized forms. The linearised form permits well surge condition prediction for multistage axial compressors, while the non-linear form is able to investigate the growth of local flow disturbances, and helps to develop practical control strategy. Validations were carried out using the data from several aircraft engine compressors. A good experiment-model consistency is achieved.展开更多
基金supported by the National Natural Science Foundation of China,project No.50906085International S&T Cooperation Program of China,project No.2013DFR61080
文摘This research investigates the use of single dielectric barrier discharge(SDBD) actuators for energizing the tip leakage flow to suppress rotating stall inception and extend the stable operating range of a low speed axial compressor with a single rotor.The jet induced by the plasma actuator adds momentum to the flow in the tip region and has a significant impact on the tip-gap flow.Experiments are carried out on a low speed axial compressor with a single rotor.The static pressure is measured at both the rotor inlet and outlet.The flow coefficient and pressure rise coefficient are calculated.Then the characteristic line is acquired to show the overall performance of the compressor.With unsteady plasma actuation of 18kV and 60W the compressor stability range improvement is realized at rotor speed of 1500 r/min – 2400 r/min.
基金This research work is supported by the GEAE USA ProgrammeNational Science Foundation of China(NSFC)project No.10477012.
文摘A novel vortex identification method for the visualization of the flow field is used for the study of the stall process of a transonic compressor.The parameter η4,which is one of the five invariants formed by the stain rate and vorticity tensors from the theory of modern rational mechanics,is found to have good ability to identify vortex stretching and vortex relaxation/breakdown processes,is introduced here to identify the tip leakage vortices.Compare with former generally used DPH(dynamic pressure head) contour,the new method reveals much more flow details which may advance our understanding of the compressor behaviors.The Vortices details are revealed in both peak efficiency and near stall condition.A possible stall process is also suggested based on the vortices analysis.The tip leakage flow from mid-chord,besides leading edge leakage flow,is also considered to play an important role in the stall process.
文摘Unsteady flows and rotating stall of a low-speed centrifugal compressor are investigated by measuring vaneless diffuser wall static pressure fluctuation and internal flow fields at different small flow fluxes. During the experiment, firstly the real time static pressure fluctuations on the vaneless diffuser shroud at different circumferential and radial position were acquired by high-frequency dynamic pressure transducers. Discrete Fourier transformation analysis and cross-correlation analysis were applied to the experimental results to ascertain the rotating stall beginning operation conditions and stall cells numbers and rotating speed. Secondly, the vaneless diffuser inlet flow angle distribution along diffuser width direction was acquired by single hotwire, which was compared with SENOO＇s analysis results. At last, the internal flow fields of the centrifugal compressor were investigated with a particle image velocimetry （PIV） system at different small flow fluxes. The flow field development of vaneless diffuser and blade flow passage are given at rotating stall conditions. The experiments enrich the understanding of rotating stall flow phenomenon of the low-speed centrifugal compressor and provide full experiment data for designing high performance centrifugal compressor.
基金This project is supported by National Natural Science Foundation of China (No.50146014) National Natural Science Foundation of Xi'an Jiaotong University, China (No.573023).
文摘A numerical methodology for investigating compressor instabilities in a multistage environment is presented. The method is based on a stage-by-stage dynamic compression model and considers air compressibility explicitly throughout the compressor. It involves discretizing the compression system into distinct elements and a use of the local elemental characteristic of mean performance. The models are presented in both nonlinear and linearized forms. The linearised form permits well surge condition prediction for multistage axial compressors, while the non-linear form is able to investigate the growth of local flow disturbances, and helps to develop practical control strategy. Validations were carried out using the data from several aircraft engine compressors. A good experiment-model consistency is achieved.
