Technology Research Of Creating CFD Models And Its Verification In High Speed Train

Computational Fluid Dynamics (CFD) technology was one of the most important developments in the engineering application in 1990s. Now, it still is one of important subjects applied in engineering. In this paper, the definition of CFD is firstly described briefly including its current achievements and future trend at home and abroad.High Speed Train (HST) is one of most complex products in railway industry. The urgency and feasible decreasing the investment risk in the HST physical prototype are discussed as well. In the HST design, there are many fluid dynamic issues that should be solved urgently not only related with the inner fluid fields but also with exterior fluid fields. A typical example is when HST speed increases, its aerodynamic force increases so much that its aerodynamic performance will definitely play an more important role then before. So, in this paper, the main research works are how to create some useful CFD models and how to apply these models into HST.Due to the important of creating models, this paper first created two models related with Mach 4 and 1.83 Pseudo Shock Wave (PSW) in a two-dimensional square duct respectively. Since shock wave is a very thin discontinuous surface, capturing this kind of shock waves had been one difficult issue in CFD field. At the same time, in a pressure-vacuum supersonic wind tunnel, a high-speed color schlieren photography visualization technique is used to show the inner structure of M4 PSW, and the shear-sensitive liquid crystal technique is applied in the investigating its boundary layer. Fortunately, the results from CFD numerical simulation are very close to the experimental results. Further, the flow quantities, which are very difficult to be obtained experimentally, could be analyzed by numerical simulation. The better consistency between those results shows that the numerical simulation definitely is useful as well if we are able to put these experiments of creating models above into creating CFD models of HST.Secondly, in order to solve some engineering issues including the inner and outer fluid fields related with HST, some kinds of models have been created and proved.1. About Inner flow field(1) With regard to the fluid-solid coupling issue happened in the water tank of HST, a CFD model related with the water sway has been created, which has successfully provided maximum force into a FEA model to calculate its maximum response. The result from buckling analysis is close to the practical failure manner which indicated the CFD model is reliable.(2) With regard to the centrifugal ventilator issue, based on the CFD numerical analysis in 3D and corresponding optimum design, based multi-domain optimum software, a better design has been obtained. This is a useful demo for high-efficiency centrifugal ventilator design.(3) With regard to the air-condition vent issue, the air duct and inner air flow of HST is simulated numerically, and the numerical results close to the real one indicated this kind of CFD model is reliable.(4) With regard to the turbine supercharge compressor impeller issue, a CFD model, with 21721 r/min and pressure ratio 3.1, has been created, the shock wave phenomena are captured happen on the suction face of the long and short blades.2. About exterior flow field(1) With regard to the 3d exterior flow issue, a CFD simulation model has been created. Based on this model, the resistance influential laws, the surface pressure coefficient and the trail flow field are investigated.(2) With regard to the fast running noise issue, the LES (Large Eddy Simulation) is applied to analyze its aero-noise. The aero-noise information around the HST has been obtained including acoustic pressure, acoustic pressure level varied in time, and the power spectrum.In summarization, in this paper the innovations are as follows:(1) M4 pseudo shock wave is first numerically modeled, and its asymmetric structure is numerically obtained. The simulation result is very close with its experimental result. That means while the created CFD model is creditable, then the CFD simulation could obtain more information than test in the research field of pseudo shock wave.(2) The shear-sensitive liquid crystal technique is first applied in investigating the boundary layer fluid properties of M 4 pseudo shock wave. According to the experiment results, it is clear if liquid crystal should slowly flow during the experiment so that more information related with the stress magnitude and direction can be obtained.(3) One set of HST CFD models is created including inner and exterior flow, which include the air-condition vent system, the multi-domain optimum, water sway in coupling, aero-noise etc. The numerical results have been proved that the CFD models are reliable in engineering application.