气粒两相流传热问题的光滑离散颗粒流体动力学方法数值模拟

在气粒两相流动问题中,颗粒间以及气体与颗粒间的传热问题不可忽略.光滑离散颗粒流体动力学(SDPH)模型作为一种新的求解气粒两相流动问题的方法,已经成功应用于模拟风沙运动等问题.在此基础上,提出了SDPH方法的热传导模型,模拟了气粒两相流动问题中的热传导过程以及颗粒蒸发过程.首先引入各相的能量方程,利用有限差分与光滑粒子流体动力学一阶导数相结合的方法,处理各相内部热传导项中的二阶导数问题,基于气粒两相间温度差及对流换热系数计算颗粒与气体间的热传导量,推导得到了含热传导模型的气粒两相流SDPH计算方程组,模拟计算了圆盘形颗粒团算例及鼓泡流化床内部热传导算例,并与双流体模型计算结果进行对比,结果基本符合;其次利用离散液滴模型中的颗粒蒸发传质传热定律计算颗粒的蒸发过程,数值模拟了颗粒射流蒸发过程,并与离散颗粒模型结果进行对比,两者符合得较好,验证了该方法的准确性及实用性.

Numerical simulation of heat transfer in gas-particle two-phase flow with smoothed discrete particle hydrodynamics

Heat transfer between particles and that between gas phase and particle phase in gas-particle two-phase flow cannot be ignored. Smoothed discrete particle hydrodynamics, as a new method for solving the gas-particle two-phase flow, has been used in simulating the aerolian sand transport successfully. Based on the smoothed discrete particle hydrodynamics method, a heat conduction model is presented in this paper and is used to simulate the heat transfer processes and the particle evaporation in gas-particle two-phase flow. Firstly, the equations to be solved are presented in which the energy equations are introduced for each phase and the second derivative item in conduction is treated by combining a standard smoothed particle hydrodynamics first derivative with a finite difference approximation of a first derivative. The heat conduction between particle and gas is computed from temperature difference and heat transfer coefficient. The disc-type particle cluster problem and bubble fluidized bed are simulated and the results are in close agreement with the two fluid model simulation results. The vaporization law for discrete phase droplet is used to deal with the particle evaporation and then a jet evaporation is simulated. Numerical results all show a good agreement with the discrete particle model results. It is indicated that the new method is of good accuracy and practical applicability.
Keywords：smoothed discrete particle hydrodynamicsgas-particle two-phase flowheat transferevaporation