Numerical Simulation Of Transitional Flow In Hypersonic Boundary Layer

The transition prediction of hypersonic boundary layer is one of the hottest issues in the field of aerospace in the 21st century as well as an unsolved problem of aerodynamics. The accurate prediction of transitional flow plays an important role in the design of the configuration and heat-protection measures of aerodynamic vehicles. The development of modern computational fluid dynamics has provide a broad research platform for the numerical simulation of transitional flows, and numerous approaches to the transition prediction have been developed,which include Direct Numerical Simulation, Large Eddy Simulation, the Solution of the Parabolized Stability Equation or the Linear Stability Equation as well as Engineering Modeling of Transition. For practical engineering computation, the approach of Engineering Modeling of Transition has been widely adopted due to its advantage with regard to the computational effort and cost.In this thesis, the approach of Engineering Modeling of Transition was choosen. A correlation-based trantion model known as ? ? Re? model,which is based on SST turbulence model and local variables, was used to simulate the transitional flow of supersonic/hypersonic boundary layer.In the first part of this thesis, the simulations of the hypersonic boundary layer transitional flow on flat plate and slender cone and the internal flow of two supersonic/hypersonic inlets model were performed. By comparision between the results of these simulations and experimental data, it has been proved that the trantion model used in this thesis has the ability to simulate the transitional flow in the hypersonic boundary layer, predicting correctly the onset location and the length of transition, and the ability to simulate the influence of turbulence intensity and viscosity ratio on the onset location of transition. Meanwhile the trantion model has the ability to simulate the complicated flow phenomena such as the shock-boundary layer interaction and the flow separation etc..However, the trantion model can not accurately simulate the laminar stage of the boundary layer flow possibly due to the use of intermittence factor to amend the production term in the transportation equation of turbulent kinetic energy, which does not completely restrain the turbulence in the laminar stage. Furthermore, the trantion model lacks the ability to simulate transitional overshoot.In the second part of this thesis, three supersonic inlet projects were proposed. The first inlet has a triple-oblique-shock external compression ramp, the second one has a isentropic external compression ramp and the third one has a single-oblique-shock external compression ramp. The numerical simulations of these three proposed inlets were performed with the use of the transition model mentioned above and sequentially the aerodynamic properties of these three inlets in both design condition and off-design condition are analyzed. In design conditionIn design condition,as the most intake flow rate and the smallest cowl drag. But, the third inlet also has the largest degree of distortion of the flow field at the outlet. In off-design condition, the velocity performance curve of the third inlet is the flattest. So when the working condition is changed, the performance of the third inlet will not vary dramaticlly, i.e. the third inlet has the best performance in off-design condition.