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12 April 2004 An analysis of near-field rocket noise involving shock waves
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The near-field rocket noise involving initial shock wave is harmful to human and launching equipment. The rocket noise and shock wave are inherent flow phenomena in exhausted flow field of rocket engine in its launching stage. Experiments were conducted to research the characteristics of this special flow. Pressure was measured by piezoresistive pressure transducers with high nature frequency. The shockwave data combined with rocket noise was obtained in the experiment. This paper describes several different analytical methods in study of the pressure-time history data obtained in these experiments. In time domain, several parameters such as peak overpressure, positive duration and waveform coefficient are determined from traditional methods. The frequency band of initial shock wave can be obtained by using of these parameters. But this result is quite different from result obtained frequency domain analysis method. This is attributed to the abnormal waveform of the initial shock wave. A further analysis is performed by wavelet transform. Wavelet analysis confirms the frequency domain characteristic of initial shock wave and near-field rocket noise. Several aspects of near-field and far-field rocket noise are compared on the basis of above analysis.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Qiang Xu "An analysis of near-field rocket noise involving shock waves", Proc. SPIE 5439, Independent Component Analyses, Wavelets, Unsupervised Smart Sensors, and Neural Networks II, (12 April 2004);

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