高速数字摄影应用于流化床内颗粒旋转特性的测试

MEASUREMENT OF PARTICLE ROTATION IN CFB RISER WITH HIGH-SPEED DIGITAL VIDEO CAMERA TECHNIQUE

该文成功地把由高速数字摄影设备和大功率激光构成的测试系统应用于流化床内固相颗粒旋转可视化.为提高颗粒转速测量范围,提出了双帧频拍摄法,并进行了数学推导和实验验证.结果表明,该方法能够对两帧频最小公倍数一半内的颗粒转速进行准确的测定,实验误差小于1%.同时在一截面为200×200 mm、高为4m的冷态循环流化床实验台上进行颗粒旋转速度的初步实验研究,当截面气体速度Vg=3.5m/s时,测得450～850μm透明玻璃珠在布风板以上0.98m的过渡区域内的平均旋转速度约为280r/s.

Particle rotation in a cold CFB riser with dimension of 200mm×200mm×4m （H） was visualized by using an advanced measurement system composed of a high-speec digital video camera and a high-power laser. Those parficles with special speckles or irregular shapes provide the possibility for determination of their rotational speeds. To enlarge measurement range of particle rotational speed, a dualfrequency imaging method was presented, with mathematical analysis and proving experiment. The results show that this method can perform measurements of those particles whose rotational speeds are not higher than half of the Least Common Multiple of two frame frequencies, with the experiment error lower than 1%, Furthermore, measurements of particle rotation in transition area at a height of 0.98m above the distributor plates in a cold CFB riser were carded out and the average particle rotational speed is found to be as much as 280r/s at superficial gas velocity Vg=3.5m/s and particle diameter dp=50-850μm.