平面气固撞击流周期振荡的模拟分析

Simulation and analysis of periodical oscillation of gas-solids two-phase planar opposed jets

由于喷嘴截面的高宽比远小于1,平面狭缝喷嘴撞击流可看作二维撞击流。采用欧拉双流体模型对二维气固撞击流进行数值模拟。模拟结果表明,当固相负载率m≤8.2,颗粒粒径为60μm≤dp≤175μm时,大间距的平面气固撞击流也出现了周期振荡。通过分析射流轴线上不同位置的压力和速度的瞬时值和平均值,认为周期振荡是由于撞击面上压力释放和持续射流的共同作用导致。讨论了不同条件对振荡周期的影响:振荡周期随喷嘴间距或颗粒粒径的增加而增加;而随射流Reynolds数的增加或者固相负载率的增加而减小。

As the ratio of height-to-width of planar nozzle is less than 1, the planar opposed jets are regarded as two-dimensional impinging streams. A numerical study of gas-solids two-phase planar opposed jets was conducted by using two-fluid model （TFM）. It was concluded that periodical oscillation was the main flow regime for large nozzle separation with ratio of particle-to-gas mass flow m≤ 8. 2, particle diameter 60 um≤dp≤175 um and ratio of nozzle separation （L） to nozzle height （H） 12--20. This oscillation was resulted from pressure release on the impinging surface and the inertia of incessant axial jets, which was based on the instantaneous and mean distributions of static pressure and velocity at the jet axis. The effects of different simulation conditions on oscillation period were discussed. The period would be increased by enlarging nozzle separation or increasing particle diameters, while the period would be decreased by increasing jet Reynolds number or ratio of particle-to-gas mass flow.