动壁作用下流化气量对粉末供给特性的影响研究

Effects of Gas Flow Rate on Powder Supplying Characteristics under the Action of Moving Wall

粉末燃料流化输送特性是粉末发动机燃料供给系统设计的一个关键,为深入研究粉末燃料的流化特性,本文基于气固双流体模型,通过UDF实现活塞运动,初步建立了考虑运动壁面作用下的稠密气固两相数值计算模型,并开展了不同流化气量条件下粉末燃料的流化过程以及流化特性研究。结果表明:在启动阶段,不同工况下气体对颗粒的卷吸输出量均大于理论流量,同时粉末储箱内压强和运动壁面受力均大于稳定输送阶段,且颗粒输出量和粉末储箱压强均随流化气量的增大而增大;在稳定输送阶段,运动壁面向前推送的粉末量与流化气卷吸的粉末量达到动态平衡,不同工况下都能形成较为稳定的气固型面,且粉末平均流量均小于理论流量,粉末平均流量随着流化气量的增大而增大,颗粒床层的高度随着流化气量的增大而降低。

The fluidization and transportation characteristics of powder fuel is a key to the design of fuel supply system of powder engine.In order to deeply study the fluidization characteristics of powder fuel,a numerical simulation method based on the two fluid model for dense gas-solid is built,which considers the action of moving wall through user defined function(UDF),and the influence of gas flow rate on the fluidization and characteristics of powder fuel are analyzed numerically.The results show that in the start-up stage,the powder mass flow rate entrained by fluidized gas under different cases is greater than theoretical flow rate,the pressure in powder storage tank and the force on moving wall are greater than that in steady stage,and the particle output and powder storage tank pressure increase with the increase of fluidized gas flow rate.In steady stage,the mass flow rate of powder pushed forward by the moving wall and the powder mass flow rate entrained by fluidized gas reach a dynamic balance.A relatively stable gas-solid interface can be formed under different cases,and the average powder flow rate is less than the theoretical flow rate.The average powder flow rate increases with the increase of fluidized gas flow rate,and the height of powder bed decreases with the increase of fluidized gas flow rate.