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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2018, Vol. 39 ›› Issue (1): 21090-021090.doi: 10.7527/S1000-6893.2017.021090

• Review • Previous Articles     Next Articles

Review and recent advances in uncoupled algorithms for chemical non-equilibrium flows

LIU Jun1, DONG Haibo1, LIU Yu2   

  1. 1. School of Aeronautics and Astronautics, Dalian University of Technology, Dalian 116024, China;
    2. Department of Space Equipment, Aerospace Engineering University, Beijing 101416, China
  • Received:2016-12-30 Revised:2017-03-23 Online:2018-01-15 Published:2018-01-15
  • Supported by:
    National Natural Science Foundation of China (91541117, 11532016)

Abstract: Numerical simulation of supersonic chemical non-equilibrium flow is a challenge in computational fluid dynamics because of two main reasons. First, the physical process is very complex because many interactions occur between shock waves and other intricate phenomena. Second, the supersonic chemical non-equilibrium flow is a typical space-time multi-scale physical problem, and its governing equations can result in serious rigidity to significantly affect numerical simulation. This paper concentrates on an introduction of Liu's uncoupled methods for simulating chemical non-equilibrium flow, following a brief review of the development home and abroad. In Liu's method, the flow equations use frozen flow model, and the reaction source equations simulate chemical reaction process in the local adiabatic and constant volume thermodynamic system. The temperature-independent enthalpy is separated from the energy term by introducing the equivalent internal energy and equivalent specific heat ratio. The flow and source equations are solved using different operators. Different from classical uncoupled methods, the solution for source term equation includes simultaneous change of state parameters and components. Considering Liu's uncoupled method and the space mean characteristic of the finite volume method, this paper also introduces recent advances in improving computational efficiency, including the flow equation optimization method and the optimization of the coupling process. Numerical simulation of shock-induced combustion is conducted using the optimization method, and the accuracy of the method is verified by comparing the results with those in literature. The chemical non-equilibrium reaction is found to occur only locally. According to the mass production rate criterion, the feasibility of the method is verified using the corresponding simulation results, and the computational efficiency of the chemical reaction operator can be improved.

Key words: non-equilibrium flow, uncoupled algorithm, finite volume method, structured mesh, numerical

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