Computational Investigation of Stagnation-Region Gas Injection for Protection of a Locally Heated Skin

Type III and IV shock interactions on the scramjet cowl principal edge produces localized heating of surfaces and leads to thermo-structural failure. One of the methods to protect these surfaces is by blowing shock away with supersonic injection of coolant into stagnation region. The displacement of shock depends on the mass flux ratio of supersonic jet and free stream of projected area. The strength and type of shock interference depends on the location of shock generator. Computational analysis carried out to evaluate the effectiveness of this method with the above parameters. The contours of flow field presented. Shock standoff distance and effective heat flux reduction computed. Geometry and structured grid generated using ICEM CFD. The simulations carried with ANSYS CFX. It found that the minimum shock standoff distance to protect the structure is with mass flow ratio of 0.34. Computed shock standoff distances for the mass flux ratios of zero, 0.17, 0.34, and 0.51 are 4, 8, 12, and 19 mm respectively. The standoff distances are successive integer multiples of zero mass flux standoff distance.