LBE simulation of impinging stream inside a T-junction mixer

作     者：XU WenKai ZHANG QingChen GUI Nan ZHANG ZiWei 

作者机构：College of Mechanical and Transportation EngineeringChina University of PetroleumBeijing 102249China Beijing National Railway Research&Design Institute of Signal&Communication Co.Ltd Institute of Nuclear and New Energy TechnologyCollaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China 

出 版 物：《Science China(Technological Sciences)》 (中国科学（技术科学英文版）)

年 卷 期：2018年第61卷第7期

页      面：1038-1055页

核心收录：

学科分类：080704[工学-流体机械及工程] 080103[工学-流体力学] 08[工学] 0807[工学-动力工程及工程热物理] 0801[工学-力学（可授工学、理学学位）] 

基　　金：supported by the National Natural Science Foundation of China(Grant No.51576211) the Foundation for the Author of National Excellent Doctoral Dissertation of China(Grant No.201438) 

主　　题：impinging flow lattice Boltzmann method T-junction heat transfer flow characteristics 

摘      要：Lattice Boltzmann Equation(LBE) method is utilized to simulate impinging stream(IS) in a T-junction mixer using a TD2G9 model. It aims to investigate the influence of Reynolds number(Re), aspect ratio of outlet diameter to inlet diameter, ratio of opposite inlet velocities, and the thermal boundary conditions on flow, mixing and heat transfer characteristics. In particular, the vortex evolution, velocity distribution, mixing index and Nusselt number(Nu) distribution in the T-junction mixer are explored in details. Four types of vortices and flow regimes are observed. The instantaneous and time-averaged flow and thermal fields,including vortex structure, transition of flow regimes, streamline and the Nusselt number distribution are discussed. Distinct quantitative transitions, even for dramatic change, are observed near the critical Re. At a low or moderate aspect ratio, the symmetric coherent structure is observed in an unstable flow regime. At a larger aspect ratio, the flow in the T-mixer becomes turbulent and asymmetric. The unequal injections velocities of the nozzles impose significant influence on the flow structure,mixing and heat transfer in vertical tube. Using larger difference between the two inlet velocities can result in more obvious change in flow characteristics. Moreover, mixing index is found to be valid in evaluating the mixing degree under a sinusoidal inlet velocity.