基于Morlet小波变换的自振射流瞬态特性影响因素分析

Instantaneous characteristics analysis of self-resonating water jet based on Morlet wavelet transformation

针对喷嘴腔内流体流动为典型的具有时变特性的非定常流动,提出采用时频分析方法对喷嘴腔内流体压力脉动信号进行分析。首先,通过Morlet小波变换联合小波脊线方法提取自振射流喷嘴腔内流体压力脉动信号的瞬时频率。然后,研究不同来流流速、不同来流扰动频率对喷嘴腔内流体压力脉动信号瞬时频率的影响。在此基础上,研究自振射流打击到打击靶上形成的反射压力波对喷嘴腔内流体瞬态特性的影响,以及不同靶距的影响。结果表明:本文方法可有效辨识来流扰动频率、来流流速对喷嘴腔内流体瞬态特性的影响,获取了试验用喷嘴的最优靶距范围,并辨识了反射压力波的影响,为研究自振射流瞬态特性的影响因素提供了有效手段。

Self-resonating water jet is a typical non-stationary,time-varying signal.With regard of this characteristics,a time frequency analysis method is applied to analyze the pressure pulsation signal in the cavity.First,the Morlet wavelet transforms coupled with wavelet ridge is employed to acquire the instantaneous frequency of self-resonating water jet,and analyze the influences of different inflow velocities and different disturbance frequencies on the instantaneous frequency.Then,the reflect pressure wave is studied,which is generated by the self-resonating water jet impacting to different target distances.The results show that the employed method can identify how different inflow velocities and disturbance frequencies influence the instantaneous characteristics of the self-resonating water jet,obtain the optimal range of the target distance,also identify the influence of the reflectpressure wave.This work provides an effective method to study the influence factors of the instantaneous characteristics of self-resonating water jet.