短時間FETとウィグナー分布によるジェットスクリーチの時間-周波数解析

概要

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Non-stationary signals must be represented in a time-frequency analysis because such signals vary with time. The purpose of the present study is to analyse a degree of a non-stationary sound such as a jet screech, is a type of shock-associated noise which is induced by the flow. In particular, when the pressure ratio (jet pressure/ambient) is higher than about 3.0 in an underexpanded mode, the non-stationarity of the noise is very strong. In this research, a short time Fourier transform (STFT) and Wigner-Ville distribution (WD) have been used to analyse a jet screech represented in a time-frequency domain. An attractive feature of the STFT is its superior in frequency precision. On the other hand, WD has superior ability in resolution of a time-frequency. However it sufferes a bad influence of cross terms. which yield spurious peak spectra. Finally, it is shown that the optimum application to analyse of a jet screech is possible by using STFT and WD method collaterally.
一般社団法人日本機械学会の論文
1997-08-25