大质量数差双组分气体混合物流场及丰度场的数值研究

Numerical Study on Flow Field and Abundance Field of a Binary Gas Mixture with Large Mass Number Difference

在研究旋转圆筒中混合气体的流场及丰度场时,对于旋转圆筒中质量数差别较大的混合气体,流动与组分输运问题的耦合是数值模拟中的难点。本研究以归一化后质量数为0.93和0.07的双组分气体混合物为研究对象,确定大质量数差双组分气体混合物物性参数的计算方法,采用有限差分法离散流体动力学方程,并用同伦延拓修正的牛顿法耦合求解强扰动下的流动方程与扩散方程,通过数值模拟给出全回流情况下,高速旋转圆筒中双组分气体混合物流场及丰度场的分布情况。数值模拟结果表明,混合气体中各组分的环流有较大差别,重组分环流集中于圆筒侧壁,而轻组分的环流分布在整个计算区域;旋转圆筒中大质量数差双组分气体混合物在较强的驱动环流作用下仍呈现径向分离的性质;侧壁温度驱动和机械驱动都会增强双组分气体混合物的轴向丰度梯度。

In study of the flow of an isotopic gas mixture in a rotating cylinder,the isotope approximation method is generally introduced to decouple the flow problem of the mixed gas and the component transport problem by considering the small molecular weight difference.However,the isotope approximation is no longer applicable to the flow of a mixed gas with large mass difference in a rotating cylinder,and the coupling of flow and component transport problem is a difficulty in numerical simulation.Taking the normalized mass numbers of 0.93 and 0.07 of a binary gas mixture as the gas under consideration,this paper discusses the calculation method of the physical property coefficients of the binary gas mixture with a large mass difference.The fluid dynamic equations are discretized by a finite difference method,and the coupled flow and component transport equations under strong disturbance are solved by a Newton method modified by a homotopic continuation.The distributions of the flow field and concentration field of the binary gas mixture in the rotating cylinder under total reflux condition are obtained by numerical simulation.The results show that the flow circulation of each component in the mixed gas is very different.The circulation of the heavy component is concentrated near the side wall of the cylinder while the circulation of the light component circulation is distributed throughout the whole computational domain.The binary gas mixture with large mass number difference in a rotating cylinder shows radial separation under strong driving circulation.The axial abundance gradient of the binary gas mixture is enhanced by the side wall temperature disturbance and mechanical drive.