激光熔覆沸腾式送粉器气固两相流数值模拟研究

Numerical simulation of gas-solid two-phase flow in fluidized bed based powder feeder for laser cladding

为了改进激光熔覆沸腾式送粉器的性能,对送粉器的送粉过程运用FLUENT软件进行了3维非定常的气固两相流仿真。通过对比Syamlal-O’Brien,Gidaspow,Mckeen和修正的Syamlal-O’Brien曳力模型中Ni基合金粉末输送的模拟结果,发现Mckeen模型得到的粉末流量与实验值相符。利用Mckeen模型,分别对不同沸腾气流量进行计算,其平均的粉末流量也与实验值接近,从而确定了Mckeen曳力模型适用于该类送粉器的数值模拟;并分析了2.6L/min的沸腾气流量下的气体与粉末的流化特性。结果表明,沸腾进气口2对送粉的影响不大,关闭该气流入口也可得到很好的送粉结果。这为激光熔覆送粉器结构改进和优化提供了理论依据。

In order to improve the properties of fluidized bed based powder feeder for laser cladding, 3-D unsteady gas-solid two-phase flow during the powder feeding process was simulated with FLUENT software. The simulation results of Ni-based alloy powder feeding process in Syamlal-O＇ Brien, Gidaspow, Mckeen and modified Syamlal-O＇ Brien drag law model were compared, which show that the mass flow rate obtained from Mckeen drag model is consistent well with the experimental results. And the simulation results of different fluidizing gas flow rate also agree well with the experimental results, which indicate that Mckeen model is suitable to simulate this kind of powder feeder. Fluidizing characteristics of gas-solid flow rate in 2. 6L/min were analyzed, which shows that fluidizing gas flow inlet 2 has little effect on powder feeding. Thus fine powder delivering characteristics can also be achieved without fluidizing gas flow inlet 2. Therefore, the numerical simulation in Mckeen model can provide a theoretical basis for optimization of powder feeder for laser cladding.