改变结构参数对旋流喷嘴内外两相流场的影响

针对一种超细粉体旋流分散喷嘴,在不同进气角度和出口锥角的条件下,采用雷诺应力湍流模型(RSM)并考虑气体的可压缩性,对喷嘴内部及出口附近的强旋、跨声速流场进行了模拟,同时结合离散相模型研究了1~10μm粒子的运动轨迹和质量浓度分布规律.结果显示:改变旋流喷嘴的进气角度对旋流强度和湍流强度影响不大,而出口锥角改变时,喷嘴内的旋流强度有明显变化;随着颗粒密度或出口锥角增大,或进气角度减小,旋流喷嘴内粒子的临界逃逸粒径相应减小;在喷嘴后方,颗粒相达到较好的扩散均匀性所需的掺混距离约为20倍喷嘴出口直径. 

Effect of structural changes of swirl nozzle on two phase flow

Contraposing a swirl nozzle for aerodynamically dispersing superfine powder,the Reynolds stress model was used to simulate the strongly swirling,compressible and transonic gas flow inside and outside the nozzles with different inlet angles and exit-cone angles.Meanwhile,combined with discrete phase model,a further study was conducted on the tracks and concentration distribution of particles between 1μm and 10μm.The results show that it has little effect on the swirl strength and turbulence intensity when changing the inlet angle.However,the swirl strength changes significantly in the nozzles,when the exit-cone angle is changed.The critical diameter of particles which can escape from swirl nozzle decreases as the particle density or exit-cone angle goes up,or as the inlet angle decreases.In the rear of the swirl nozzle,in order to obtain a good uniformity of concentration distribution,particles need to diffuse through a distance of about 20 times of the diameter of the nozzle outlet.