旋风分离器内气固两相流动特性的LES-DEM研究

LES-DEM Investigation of the Gas-Solid Flow Characteristics in a Cyclone Separator

针对旋风分离器内复杂的气固两相流动特性,本文采用LES-DEM耦合方法进行了研究。其将固相视作离散体系,在拉格朗日框架下采用牛顿运动定律对颗粒进行跟踪;气相视作连续介质,在欧拉框架下采用LES方法对流场进行求解。结果表明:旋风分离器内气流速度在各个方向上呈现不同的分布特征。进出口压降在平均值附近波动,颗粒质量流率的增大会降低压降。颗粒沿壁面螺旋下降并被捕集,少量由于短路流而从排气管逸出,其在旋风分离器内的停留时间符合正态分布规律。

The complicated gas-solid flow characteristics in a cyclone separator are investigated with the LES-DEM coupling method.In this method,the solid phase is treated as a discrete system where particles are tracked by Newton＇s law of motion under the Lagrange framework,on the contrary,the gas phase is regarded as a continuous medium where the flow field is solved by LES method under the Eulerian framework.Results show that the velocity distribute characteristics of the gas phase vary in the directions.Pressure drop between inlet and outlet fluctuates around an average value,and it will be decreased with the increase of the particulate mass flow rate.Particles close to the wall spiral down and are trapped finally,meanwhile,a small amount of particles escape from the vortex finder due to the short circuit flow,and the residence time of particles in the cyclone is in line with normal distribution.