基于小波变换的SK型静态混合器速度脉动特性研究

Study on characteristic of velocity pulse in SK static mixer based on wavelet transform

以SK型静态混合器为研究对象,运用激光多普勒测速仪对管内流体的速度脉动信号进行检测,运用小波变换分析检测信号来研究其速度脉动特性。分析结果表明,SK型静态混合器内轴向速度脉动以低频脉动为主,其脉动信号经db7小波5级分解后,低频信号的峰值明显高于高频信号的峰值,且低频级信号的能量占信号总能量的绝大部分,低频峰值对应频率基本在(3～13)Hz范围内,最高不超过20Hz;在其半圆形流道中心区域,轴向速度脉动的峰值相对较高而峰值对应频率相对低,在靠近边界区域轴向速度脉动的峰值相对较低而峰值对应频率相对较高。

Wavelet transform was used to analysis the characteristic of velocity pulsated signals in SK-static mixer,which were measured by using of LDV. The results showed that the signals of axial velocity pulse in mixer were mainly of low frequency. After the velocity pulsated signals were decomposed to five classes by db7 wavelet,the peak of low-frequency signals was significantly higher than that of high-frequency signals and the energy of low-frequency signals was the majority of the total energy. The fre- quency of low-frequency peak focused on the band of （3 to 13）Hz basically,none beyond 20Hz. In the central area of the semi-circular conduit,the peak of velocity pulse was comparatively higher but the corresponding frequency was lower,which reversed in the verge.