基于DEM模拟气固鼓泡床中颗粒碰撞参数对流场间歇性的影响

采用计算流体力学和离散元(CFD-DEM)方法研究鼓泡床内的气固流动状态,考察了颗粒弹性系数和恢复系数对流场间歇性的影响,并利用小波变化分析方法分析了颗粒弹性系数和恢复系数对流场相干结构的影响。研究结果表明:颗粒弹性系数和恢复系数对颗粒速度脉动能、床层平均高度、平坦因子以及流场间歇性有一定影响。随着颗粒弹性系数取值的变大,高频区能量和平坦因子先降低后增加,床层高度先增加后降低,流场间歇性先减弱后增强;颗粒恢复系数取值越大,高频区能量和平坦因子越低,床层高度越大,流场间歇性越弱。

Effect of granular collision parameters on DEM simulation of flow field intermittency in gas-solids bubbling fluidized bed

The gas-solids flow in a bubbling bed was simulated by the combined approach of computational fluid dynamics (CFD) and Discrete Element Method (DEM). The influence of granular collision parameters of particle elasticity coefficient and restitution coefficient on flow field intermittency was investigated. The continuous wavelet transform analysis was used to obtain the coherent structure behavior influenced by particle elasticity coefficient and restitution coefficient. Particle elasticity coefficient and restitution coefficient had some effect on fluctuating energy of particle velocity, mean bed height, flatness factor, and flow field intermittency. With increasing particle elasticity coefficient, the energy in high frequency domain, flatness factor and flow field intermittency decreased first and then increased, while mean bed height increased first and then decreased. The larger the restitution coefficient, the lower the energy in high frequency domain and flatness factor, and the higher the mean bed height, the weaker the flow field intermittency.