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Drag and heatflux reduction using counterflow jet and spike - Analysis of their equivalence for a blunt cone geometry at Mach 8
Author(s): B. John, Divik Bhargava, Saumya Punia, Parv Rastogi
Keywords: Counterflow injection, Physical spike, Blunt body, Hypersonic, drag reduction, Aerodynamic drag, shock interaction, Recirculation region.
This study aims to explore equivalence between active and passive flow control techniques in reducing the wave drag and surface heat flux over a blunt cone model kept in Mach 8 stream. Computational investigations were carried out by using finite volume based compressible flow solver of Ansys Fluent v.18. Throughout the study, the solutions of governing equations are sought by assuming two dimensional-axisymmetric nature of the flow field. Both counter flow-stagnation point injection and forward facing-physical spike are considered to mitigate the excess drag and heat flux experienced by a blunt body representing the nose cone section of a hypersonic vehicle. Eventually, on the basis of identified drag reductions, the present study proposes equivalence cases between these two methods. It is shown that a pointed spike of L/D=1 provides almost the same drag reduction as counter flow injection jet with a pressure ratio of 8.25. Similarly other equivalence cases are identified and the physics behind them is explored. The identified equivalence is expected to help the designers in effectively replacing one technique with another, according to the requirement. Equivalence matrix is presented for different spike cases in terms of injection ratios of counter flow injection.