撞击流混合器内速度脉动的间歇性分析

应用激光多普勒测速仪(LDA),对撞击流混合器的流场速度进行了实验测量.利用小波变换模极大值方法与分形理论结合,对撞击流混合器撞击区的速度脉动信号进行多重分形分析,计算其轴向和径向速度信号的间歇性指数,并与相关流动特性进行关联分析,探讨撞击流混合器撞击区非线性、非均匀性和混沌特性机理.通过分析同一转速不同位置和同一位置不同转速下的信号得出:撞击流混合器内部流体流动具有多重分形的特性,通过间歇性参数随位置变化出现的最低拐点可以判断混合器内部流体运动特征,得出流型的转变区域;转速对撞击区的影响大于对回流区的影响.为揭示撞击流混合器的流动机制提供了一种新的方法.

Intermittence analysis of velocity pulse signal in impinging stream mixer(ISM)

The velocity of flow field in impinging stream mixer(ISM) was measured with laser Doppler anemometry(LDA).The multi-fractal analysis for velocity pulse signal in the impinging region of ISM was performed by using the maximum method of wavelet transform modulus.The intermittence index of the axial and radial velocity signals was calculated with this method.Non-linearity,non-uniform character and chaotic behavior of fluid system in ISM were discussed by integrating the flow characteristic.The signals on different positions at the same rotation speed and different rotation speeds at the same position were analyzed.The results show that velocity pulse in ISM take on a multi-fractal character,the lowest turning point of intermittence index figure can be used to estimate the inner flow characteristic and transition of flow pattern in ISM,and the influence of rotating speed on impinging area is more remarkable than that on refluence area.This offers a new method for revealing the fluid mechanism in ISM.