等离子体点火密闭爆发器中压力信号的小波分析

Wavelet Analysis of Pressure Signals in a Closed Bomb Ignited by Plasma

采用小波阈值法对等离子体点火密闭爆发器实验的压力信号进行降噪,选择平滑度和均方根误差建立多指标融合的评价体系,比较不同小波基函数、阈值方法、分解级数等条件下密闭爆发器实验压力信号的去噪效果,根据评价指标选择去噪效果最佳的小波参数。计算结果表明,小波基函数为db8,分解级数为8,阈值采用Birge-Massart策略,使用软阈值方法处理后的信号去噪效果最佳。应用势平衡理论分析去噪后的密闭爆发器实验压力曲线,确定与发射实验压力曲线的势平衡点相对应的等效势平衡点,分析不同输入电能条件下密闭爆发器实验等效势平衡点处ψ_(e)值的变化,从而研究发射药燃烧特性。结果表明:在密闭爆发器实验中,等离子体作用下等效势平衡点处压力升高,达到等效势平衡点时间缩短,相应的ψ_(e)值减小。

The wavelet threshold method is used to denoise the pressure of closed bomb experiments with plasma ignition.Smoothness and root mean square error are selected to establish the multi-index evaluation system.The denoising effects of experimental pressure signals of closed bomb with different wavelet basis functions,threshold methods and decomposition levels are compared.According to evalua-tion indices,the wavelet parameters with the best denoising effect are selected.Computational results show that when the wavelet basis function is db8,the decomposition set to 8 and the threshold adopts the Birge-Massart strategy,the best denoising effect is obtained by using the soft threshold method.The theory of potential equilibrium is applied to analyze the experimental pressure curve of the closed bomb after denoising,and the equivalent potential equilibrium point corresponding to the potential equilibrium point of the the pressure curve of the launch experiment is determined.The variation of theψ_(e) value at the equivalent potential equilibrium point in closed bomb experiments with different electric energy inputs is analyzed,and the combustion characteristics of the propellants are studied.The results show thatthe pressure at the equivalent potential equilibrium point increases in a closed bomb experiment under the action of plasma,the time to reach the potential equilibrium point shor-tens,and theψ_(e) value decreases.