Direct Numerical Simulation of Hypersonic Boundary Layer Transition for Heat Transfer Prediction

The prediction of laminar-turbulent transition of hypersonic boundary layers is critically important to the development of hypersonic vehicles that are to be used for rapid global access. Boundary layer transition has first-order impacts on aerodynamic heating, as well as drag and control of hypersonic vehicles. The success of transition and related heating prediction relies on the good understanding of the relevant physical mechanisms leading to transition. In spite of considerable efforts in experimental, theoretical, and numerical studies, many critical physical mechanisms underlying hypersonic boundary-layer transition are still poorly understood. The purpose of this STTR Phase I effort is to develop, validate, and demonstrate a robust and accurate DNS computational tool for predicting wall heat transfer rates in transitional hypersonic boundary layers. The DNS can also predict the heat transfer overshoot at transition. The main idea is to develop DNS tools for the simulation of complete transition process of hypersonic boundary layers over blunt cones under realistic freestream noise and other disturbances. There are four specific research tasks to be carried out in a nine month period for the proposed STTR Phase I project. First, we will develop and validate a prototype 3-D DNS computer code for hypersonic boundary-layer transition and heat transfer prediction. Second, we will validate the new DNS computational tool against benchmark experimental datasets obtained from the open literature. Third, we will conduct some initial DNS of boundary layer transition on hypersonic boundary layer over a blunt cone for Mach 5.5 flow over blunt cones, which correspond to Stetsons shock tunnel experiments. The transition simulation consists of separate receptivity and nonlinear breakdown simulations. Fourth, we will begin efforts for developing a product usable by a non-specialist, and formulate plan for Phase II development. BENEFIT: Military applications include Long-Range and Prompt Global Strike Options and Rapid Access to Space. Commercial applications include commercial space access, supersonic civilian transport, and aircraft engine design. The CFD software to be developed under this program will also be useful for academic and research institutions.)