Heat Transfer Prediction in Transitional Hypersonic Flow

Accurate prediction of heat transfer in hypersonic boundary layers undergoing transition from laminar to turbulent regime is a technical challenge. Heat transfer overshoot at transition region is of particular interest here. We have proposed a two pronged approach for this problem. On one hand we will conduct very accurate Direct Numerical Simulation (DNS) studies to understand the mechanisms of the transition process. This will be done at the academic institution. The initial DNS studies will have artificial triggering of transition by suction/blowing boundary conditions at an upstream slot to reduce domain size. Later, a comprehensive DNS investigation of the naturally occurring transition region will be carried out.  CASCADE will undertake a modeling approach using Reynolds Averaged Naiver Stokes (RANS) simulations. Specifically, the v2f turbulence model will be used for its ability to handle turbulence anisotropy encountered in boundary layer flows. An intermittency based transition model will be the starting point. The idea is to artificially alter the turbulence energy redistribution in at the transition onset to generate the overshoot. The detailed understanding of the transition regime gained from DNS studies will help in modifying the turbulence energy redistribution in a physically meaningful manner. BENEFIT: It is envisioned that a successful completion of the project will lead to an enhanced understanding of the physical mechanisms behind the transition regime of hypersonic boundary layers. Especially, the processes behind the overshoot at the onset of transition will be thoroughly understood from the Direct Numerical Simulation (DNS) studies. This will ultimately result in the development of advanced transition models based on the Reynolds Averaged Navier Stokes (RANS) approach. Specifically, the outcome will be a modified v2f model capable of handling transitional flows in hypersonic systems. The developed tool will be immensely useful to the designers of hypersonic vehicles subjected to extreme thermal loads. Any industry involved in space access, supersonic flight and aircraft engine design will be potentially benefited. All these sectors can be targeted for licensing opportunities for our tools that will be developed from this project. The knowledge gained will also enable us to do consulting for the industry.)