激波驱动稠密固体相微米颗粒群加速性能的实验研究

Experimental investigation of acceleration performance of dense-solid-phase micron particles driven by shock waves

设计水平激波管-加速直管段-装载室-尾喷嘴组合装置,利用动态压力测量和高速摄影技术,实验研究了不同尾喷嘴类型、颗粒直径、马赫数和装载比下伴随激波和微米级稠密固体颗粒相的气固两相流现象和颗粒加速规律。得出:(1稠密颗粒相时,喷嘴类型对颗粒群加速效果排序可能为扩张型>收缩型>缩放型,与稀颗粒相情形不同,必须考虑激波衰减、颗粒团聚、壁面摩擦和颗粒拥堵的影响;2直径越大,颗粒加速效果越好,不能以单颗粒直径估计曳力大小,须考虑颗粒团聚的影响;3激波马赫数越大,颗粒群加速效果越好;4颗粒装载比较小时,颗粒群在收缩喷嘴内的加速效果较好,但装载比达到一定程度后,其进一步增大影响不大。

Aiming at the issues of the gas-solid two-phase flow phenomena, which are accompanied by shock waves and under the condition of dense solid phase composed of micron particles, and for the sake of making clear the acceleration performance of particles, a series of experiments were conducted to investigate the influences of the key parameters including type of tail nozzles, mean diameter of particles, shock Mach number and loading ratio of particles. In these experiments, a composite setup, consisting of end-to-end connections of a horizontal shock tube, a constant- section straight tube, a particle loading room and a tail nozzle, was employed and furnished with the instruments of dynamic pressure measurement and high-speed photography. The results are summarized that in event of dense particle phase, the priority of acceleration performance of particles in different types of tail nozzles could be ranked as ： the first is in a divergent nozzle, the second is in a convergent nozzle, and the last is in a convergent-divergent one, that is of difference from that under the condition of dilute particle phase. Therefore, it should be taken into account that the influences of possible attenuation of incident shock wave, agglomeration of particles, friction force on nozzle wall and blockage of particles on the acceleration performance of particles. Greater diameter of particles corresponds to a better acceleration effect, implying that the effect of agglomeration of particles should be considered for the evaluation of drag force other than the bare consideration of the diameter of a single particle. The acceleration performance of particles is better for a larger shock Mach number. The acceleration performance of particles in a convergent nozzle decreases as the increase of loading ratio, however, no response on acceleration performance of particles would happen to a further increase of loading ratio after loading ratio reaches a certain value.