Flow instability in the centrifugal compressor should be detected and avoided for stable and safe operation.Due to the popularity of electric centrifugal compressors,instability detection could be achieved by measurin...Flow instability in the centrifugal compressor should be detected and avoided for stable and safe operation.Due to the popularity of electric centrifugal compressors,instability detection could be achieved by measuring motor signals instead of traditional aerodynamic signals.In this paper,the feasibility of instability detection by motor signals(i.e.rotating speed and phase current)was studied experimentally.The physical structure and control method of the electric centrifugal compressor were discussed to reveal the potential of instability detection by motor signals.Dynamic pressure signals and motor signals measured during unsteady experiments were analyzed in the time domain and frequency domain.Characteristics of these signals were then compared under different operating conditions to indicate the feasibility of instability detection by motor signals.Finally,the ability of Short-Time Fourier Transform(STFT)of rotating speed signals in real-time instability detection was discussed.Results showed that the rotating speed signal is a good alternate for instability detection in spite of signal distortion,while the phase current signal can only detect surge due to the low resolution of the controller.Based on the variations of the amplitude and frequency of rotating speed signals,the real-time instability can be captured accurately by STFT with a window size of 0.5 s.Besides,the interference caused by the controller can be removed by STFT.展开更多
A wave rotor is suitable for compact and efficient pressure-exchange between gas flows.This work measured the circumferential pressure distribution of the rotor/stator interfaces and utilized a CFD method to simulate ...A wave rotor is suitable for compact and efficient pressure-exchange between gas flows.This work measured the circumferential pressure distribution of the rotor/stator interfaces and utilized a CFD method to simulate the unsteady pressure waves.The experimental and CFD results showed some slopes in the circumferential pressure distributions,and the slopes indicated the traces of specific unsteady pressure waves.Such traces varied regularly if the rotational speed varied within a range from-11%to+11%off the baseline value,but they were seriously disturbed if the rotational speed varied by-45%from the baseline value.It verified that a pressure wave in a wave rotor tended to keep its pressure ratio and propagation velocity unchanged if the rotational speed varied by a small extent,and that the pressure wave could not keep its propagation patterns if the rotational speed varied by a large extent.Because of the pressure wave behaviors,the wave rotor demonstrated specific regulations of the rotational speed effects on its operational states.展开更多
基金supported by the National Key Research and Development Program of China(No.2018YFB1501004)。
文摘Flow instability in the centrifugal compressor should be detected and avoided for stable and safe operation.Due to the popularity of electric centrifugal compressors,instability detection could be achieved by measuring motor signals instead of traditional aerodynamic signals.In this paper,the feasibility of instability detection by motor signals(i.e.rotating speed and phase current)was studied experimentally.The physical structure and control method of the electric centrifugal compressor were discussed to reveal the potential of instability detection by motor signals.Dynamic pressure signals and motor signals measured during unsteady experiments were analyzed in the time domain and frequency domain.Characteristics of these signals were then compared under different operating conditions to indicate the feasibility of instability detection by motor signals.Finally,the ability of Short-Time Fourier Transform(STFT)of rotating speed signals in real-time instability detection was discussed.Results showed that the rotating speed signal is a good alternate for instability detection in spite of signal distortion,while the phase current signal can only detect surge due to the low resolution of the controller.Based on the variations of the amplitude and frequency of rotating speed signals,the real-time instability can be captured accurately by STFT with a window size of 0.5 s.Besides,the interference caused by the controller can be removed by STFT.
基金co-supported by the National Natural Science Foundation of China(No.51906007)the National Key Laboratory Foundation of China(No.6142702190204)。
文摘A wave rotor is suitable for compact and efficient pressure-exchange between gas flows.This work measured the circumferential pressure distribution of the rotor/stator interfaces and utilized a CFD method to simulate the unsteady pressure waves.The experimental and CFD results showed some slopes in the circumferential pressure distributions,and the slopes indicated the traces of specific unsteady pressure waves.Such traces varied regularly if the rotational speed varied within a range from-11%to+11%off the baseline value,but they were seriously disturbed if the rotational speed varied by-45%from the baseline value.It verified that a pressure wave in a wave rotor tended to keep its pressure ratio and propagation velocity unchanged if the rotational speed varied by a small extent,and that the pressure wave could not keep its propagation patterns if the rotational speed varied by a large extent.Because of the pressure wave behaviors,the wave rotor demonstrated specific regulations of the rotational speed effects on its operational states.
