分离器入口段颗粒间相互作用的激光全息诊断

Particles interaction in separator inlet section diagnosed by laser holography

为了进一步研究循环流化床锅炉系统的气固两相流动特性，为分离器的优化设计提供参考依据，应用多脉冲激光全息技术，对循环流化床锅炉分离器入口段气流中不同筛分颗粒之间的相互作用情况进行了试验研究。通过对所拍全息照片的分析判读，发现１００μｍ尺度的细小煤粉绕过较大的球形颗粒时几乎没有小颗粒卷入小球的尾迹，而浓相小颗粒群绕流小球时，在小球的边缘形成一个高浓度区，随后部分小颗粒进入了小球的尾迹。小颗粒在尾迹中重力作用表现明显，但未观察到回流作用使其反向运动。不规则小颗粒在行进中有明显的取向，几个长条颗粒以６５０ｒ／ｓ的速度高速转动。试验表明脉冲激光全息系统具有很好的诊断动态颗粒场的能力，是一种适合于深入研究颗粒运动细节的有效手段。

For further study of gas solid two phase flow in circulating fluidized bed boilers, a set of multi pulse laser holography system has been first used to study the particles' interaction in horizontal gas solid two phase flow. In order to reveal the influence between particles at separator inlet section in a circulating fluidized bed, this system was developed to record the flow image of fine particles going around a small sphere. The result shows that the sparse fine particles going around the sphere are not tend to travel into the wake of sphere, while if the density of fine particles is high, some of them will travel into the wake and a high density region formed at the edge of the sphere. It shows that after the fine particles travel into the wake, the gravity effects become obvious and fine particles tend to deposit. Some particles with irregular shape have large rotating velocity of about 650 rotations per second during traveling in air. Meanwhile, the experiment result shows that the laser holography system is a powerful tool for diagnosing dynamic particle field, with high resolution and large depth of field.