电弧等离子体射流核脉动及射流卷吸的实验研究

湍流是电弧等离子体射流中典型的物理现象之一。以往的研究认为，射流存在一个处于层流状态的核心区域。采用电弧等离子体光谱诊断及数字高速摄影的方法对方法对常压电弧等离子体射流核进行了研究，采用傅里叶变换的方法分析了弧电压和射流光谱强度信号。结果发现，电源的交流分量和阳极弧点运动在整个射流核的脉动特性中都有体现，射流并不存在一个处于稳定状态的核心区域。相反，从谱线强度脉动图中可以看到，射流核的脉动是由电弧电压脉动造成的，这可能是射流核脉动的最主要原因。采用多元素谱线强度法研究了射流对空气的卷吸作用，并通过氮原子谱线强度确定了氮原子数密度在射流中的分布。

EXPERIMENTAL STUDY ON THE FLUCTUATION AND ENGULFMENT OF ARC PLASMA SPRAYING JET

Turbulence is one of the characteristic phenomena in an arc plasma spraying jet.Most of the previous investigations believed that there is a laminar flow region in the core of the jet.In this work,a spectrum diagnostic system has been installed to investigate these effects with the aid of high-speed digital camera.The method of Fourier transform has been applied to the analysis on the arc voltage and light signals.The influence of the arc behavior and the power supply on the jet is everywhere.It seems that there is no laminar flow region in the core of jet.Moreover,from the light dynamic variation graph,the jet fluctuation due to the arc voltage behavior may be the dominant characteristic of the jet behavior.The engulfment of the ambient air in the jet has also been experimentally studied by means of detecting intensities of multi-spectral-line.The number density distribution of nitrogen atom in the jet has been obtained with the intensity of spectral line of nitrogen atom.