前混合磨料射流磨料速度测试的新方法

A novel method to measure the velocity of premixed abrasive jet

前混合磨料射流超强的打击力主要是由高速磨料群提供的,因此,磨料速度测试是磨料打击力分布规律等研究的基础。针对传统研究方法的不足之处,笔者提出采用PIV技术结合自主编程设计的磨料中心识别程序,实现非接触式测试手段下磨料速度测试实验研究,并利用该方法简要分析了喷嘴结构对磨料速度的影响。结果表明,在一定范围内增加直线段长度有利于提高喷嘴出口处磨料的速度,表明在喷嘴直线段末端磨料依然处于明显的加速状态;增加收敛段长度对提高喷嘴出口处磨料速度有一定的作用,但磨料速度增幅不大;收敛角较大时,液相在收敛段前半段加速缓慢而在后半段过于剧烈,因磨料颗粒加速滞后于液相的原因导致喷嘴出口处磨料速度降低。

The ultra-intense hitting power of abrasive water jet is mainly provided by high-speed abrasives. So measuring the abrasive velocity is the base to research the hitting power and the erosion mechanism. To overcome the shortcomings of traditional research methods, a new testing method was proposed. The method uses the PIV（particle image velocimetry）combined with center recognition program to gain the abrasive velocity,, and can test the high velocity of abrasive jet without contacting. Furthermore, the influence law of nozzle structure on the abrasive velocity was proceeded with this method. The results show that increasing the length of straight segment in a certain range is conducive to improve the abrasive velocity, because the abrasives were in the state of obvious accelerated motion in the end of the straight segment. Increasing the length of convergence section in a certain range is conducive to improve the abrasive velocity, but the increase amplitude is not very large. When the convergence angle is too large, liquid phase accelerates slowly in the first half of convergence section but accelerates sharply in the second half of convergence section. Then the acceleration of abrasives lags behind that of liquid phase, and thus the abrasive velocity is decreased.