Application of Wavelet Method in Analyzing Pressure Oscillation in Regenerative Liquid Propellant Gun

摘要

The spraying and combustion processes in regenerative liquid propellant gun (RLPG) always show large high-frequency pressure oscillations that appear at specific time and frequency range. To study this phenomenon, wavelet analysis is applied to analyze the pressure signal in RLPG experiment. The signal is decomposed to different frequency bands under different scales, so that all the complicated interior ballistics processes may be classified in frequency field, which is hard to achieve in time. The ignition excitation,environment interference, combustion noise and the main oscillation frequency can be judged through the analysis.In RLPG, acoustic mode is one of the main factors that cause the pressure oscillations. The displacement of piston can be gained at the time when the main oscillation frequency appears with the wavelet analysis, which is used to calculate the length of the combustion chamber.Then the acoustic modes can be predicted. Besides, all the other possible inducements that may result in high-frequency pressure oscillations in RLPG interior ballistic cycle are discussed. The wavelet analysis toolbox in Matlab software is used for obtaining the mean pressure curve which is required for updating the RLPG lumped parameter interior ballistic model. According to the characteristic that the frequency of pressure signal varies with time, the analysis precision may be improved by adjusting sample frequency and decomposed hierarchy.The way of wavelet analysis provides an effective method for analyzing the pressure signal in RLPG.