Research on vibration characteristics of engine transitional state using short equal angles resampling method

When the engine is in an unsteady operation, it is difficult to get accurate vibration characteristics only using short-time Fourier transform (STFT). In the paper, a new approach is presented to obtain accurate vibration characteristics for instantaneous state of power engine By combining the STFT and equal angles sampling, we establish a short equal angles resampling method (SEARM) using order extraction feature. To compare the effective of new approach, the STFT and SEARM are both applied to simulate and analyze the engine air parking process with Matlab software. Meanwhile, we are able to establish the practical experiment of engine transition state, and instantaneous characteristics of engine speed is obtained using the two methods. All the results demonstrated that the SEARM is more effective and accurate to extract the vibration amplitude of engine in the start to stop process. Using the frequency-amplitude or order amplitude graphs obtained by SEARM, it can be clearly found the changes of engine vibration and speed in the whole instantaneous process, which was beneficial to solve the problem of failure in engine emergency stop.