粒子图像测速技术在两相流测量中的应用研究

Study on application of PIV technique in two-phase flow measurement

为实现对两相流中各相速度的同步测量,提出了一种两相流数字粒子图像测速(PIV)方法.该方法选用合适的示踪粒子显示液体的运动,并用高速摄像机采集气液两相流动数字图像.从图像处理着手,根据图像灰度的不连续性和相似性,对采集到的两相流数字粒子图像进行分离,实现液体示踪粒子和气泡的标定.最后采用基于改进了的互相关算法得到液体流场速度分布,同时利用跟踪法得到气泡的速度分布,并对液体速度场中产生误矢量的原因进行了分析,消除了误矢量.经实例研究表明,该测量方法对硬件的依赖性小,测量成本低,可进一步推广至气固两相流的测量.

For realizing simultaneous measurement of each phase in two-phase flows by particle image velocimetry (PIV), a new method of PIV for gas-liquid two-phase flow was proposed. Appropriate tracing particles were selected in the method to visualize the liquid flow, and the digital images of gas-liquid two-phase flows were acquired by a high-speed camera. The digital image of gas-liquid two-phase flow was separated by image processing techniques based on the discontinuity and similarity of gray images, and the particles for tracing liquid and bubbles were determined respectively. The velocity field of the liquid was calculated by an improved cross-correlation algorithm, and the velocity distribution of bubbles was obtained by tracing method. Spurious vectors in the velocity field of the liquid were analyzed and deleted. The experimental results show that the new method has advantages of lower cost and less dependence on hardware, and can be extended to the measurement of gas-solid two-phase flows.