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LBE simulation of impinging stream inside a T-junction mixer

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Abstract

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.

Keywords

impinging flow lattice Boltzmann method T-junction heat transfer flow characteristics 

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Copyright information

© Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • WenKai Xu
    • 1
  • QingChen Zhang
    • 2
  • Nan Gui
    • 3
  • ZiWei Zhang
    • 1
  1. 1.College of Mechanical and Transportation EngineeringChina University of PetroleumBeijingChina
  2. 2.Beijing National Railway Research & Design Institute of Signal & Communication Co., LtdTsinghua UniversityBeijingChina
  3. 3.Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijingChina

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