Research On CFD Parallel Computing Technology And Massively Parallel Computing Platform For Chemical Non-Equilibrium Flow Problems

Airbreathing hypersonic technology studies the technology of flight vehicle for long-distance hypersonic flight in atmosphere layer or trans-atmosphere layer at flight Mach number above 5. The core of airbreathing technology is scramjet and airframe/propulsion integrated hypersonic flight vehicle. Airbreathing hypersonic flight involves a lot of complicated physical and chemical phenomena, which impose high requirements on ground testing. These requirements significantly increase the expense, period and difficulty of ground testing. With the development of computing technology, Computational Fluid Dynamics (CFD) can complete the analysis of flow parameters in a relatively shorter time, provide the detailed characteristics of flow field, and remedy the deficiency of wind tunnel and measurements, and has been widely used in the design and performance research of scramjet. Meanwhile, the scramjet flowfield simulation needs huge calculation arising from the computation of various special equations, chemical non-equilibrium flow, turbulence flow equations and transport coefficients so that it must be performed on high performance parallel computer systems by massively parallel computation.The real-world CFD parallel computation must take several important problems into accounts, such as the problem of whether the parallel result is consistent with sequential result, the parallel efficiency problem of massive parallel computing and the parallel scalability problem, etc. Furthermore, it should not only support various physical & chemical models, differential format and implicit solution method but also has the ability of dealing with different grid types. This dissertation puts forward some innovational researches on these aspects and develops a high efficient 3D parallel computing software platform AHL3D which is mainly used in non-equilibrium flow fields simulation of scramjet.On the aspect of massive parallel computation, the dissertation deploys the 1D-first regular partition algorithm and the irregular partition algorithm based on auto repartition to respectively handle the problems of large-scale and medium & small scale parallel computing. To ensure communication efficiency and data validity for complicated computation area problem, the communication is divided into three steps: dummy boundary communication, physical boundary edge communication and dummy boundary edge communication. This strategy avoids the communication singularity and repetition of some special grid points.To keep the consistency of parallel result with sequential result, a kind of pipeline technology is applied in the CFD parallel computation. A multi-dimensional pipelined parallel solution is supplied which is based on pipelined relationship directional graph.