运用FFT分析自振脉冲射流振荡特性

Analysis of Oscillation Characteristics of Self-Excited Oscillating Pulsed Waterjet by Fast Fourier Transform

针对目前煤岩破蚀与煤层割缝困难等问题,可利用自振脉冲射流振荡特性辅助其进行开采。通过快速傅里叶变换(FFT)方法对不同结构参数下喷嘴流场仿真结果进行幅频转换,探究腔体结构对振荡频率与振荡峰值的影响规律。通过频域分析发现,在特定参数(d_1=1.2mm,D=10.5mm,d_2=1.4mm,L=2.4mm,α=120°)下,自振脉冲射流的振荡峰值最大,有利于增强喷嘴振荡。与此同时,随腔径L、腔径D、前后喷组腔径比d_2/d_1增大,射流振荡频率与振荡峰值变化成正相关,与碰撞角α成负相关。相关结果及方法可为自振脉冲射流振荡特性的研究提供参考。

In order to solve the problems of coal and rock erosion and the difficulty of coal seam cutting,the self-excited oscillation pulsed waterjet can be used to assist the coal mining. Through the fast Fourier transform(FFT) method,the amplitude frequency conversion of the simulation results of the nozzle flow field under different structural parameters is carried out to explore the influence of the cavity structure on the oscillation frequency and the oscillation peak. In the frequency domain analysis,it is found that the oscillation peak of the self oscillating jet is maximum under specific parameters(d1=1.2 mm,D=10.5 mm,d2=1.4 mm,L=2.4 mm,and α=120°),which is beneficial to the enhancement of the nozzle oscillation. At the same time,with the increase of cavity diameter L,cavity diameter D,and the diameter of the front and back jet group increases,the frequency of the jet oscillation is positively correlated with the oscillation peak,which is negatively correlated with the collision angle alpha. The correlation results and methods can provide references for the study of self-excited oscillating pulsed waterjet.