Improved Transition Model with Mechanical Considerations for Hypersonic Flow

Abstract

An improved transition model with mechanical considerations is proposed in this paper for hypersonic boundary-layer transition. The original V-SST model is not suitable for hypersonic flow with low freestream turbulence intensity. Thus, three key modifications based on the physical mechanisms and multiple unstable modes, which involve the addition of source term in the transport equation, reconstruction of pretransitional viscosity, and reformulation of the control function of effective turbulence viscosity, are constructed to make it possible to predict the hypersonic transition process. Numerous validation test cases are chosen to adequately access the prediction accuracy of the current transition model, including flat plates and blunt cones with different Reynolds numbers, a double ramp, an inlet model with composite shock interference flow, and three-dimensional X-51A forebody model. The flow structures and heat transfer distributions predicted by the numerical simulation are well consistent with experimental data, which demonstrate the capability of improved V-SST transition model in accurately predicting hypersonic transition behavior and reasonably reflecting the influence of freestream unit Reynolds number. It needs to further investigate the performance of the current model in capturing unusual transition phenomenon such as heat transfer overshoot, and consider more physical influence factors on boundary-layer transition.