Effect of the axial cavity with an opposing high-pressure jet combination in a Mach 6 flow condition

• Published in: Acta astronautica Vol. 178; pp. 335 - 348
• Main Authors: Sudarshan, B., Rao, Srisha M.V., Jagadeesh, G., Saravanan, S.
• Format: Journal Article
• Language: English
• Published: Elmsford Elsevier Ltd 01.01.2021; Elsevier BV
• Subjects: Aero heating; Blunt bodies; Cavity flow; Cylindrical bodies; Flow control; Fluctuations; Forward facing cavity; Heat flux; Heat flux measurements; Heat transfer; High pressure; Hypersonic flight; Hypersonic flow; Hypersonic shock; Mach number; Nose; Oscillations; Pressure ratio; Reduction; Schlieren visualization; Shock standoff distance; Shock tunnels; Unsteady heat flux; Schlieren visualization; Unsteady heat flux; Hypersonic flow; Aero heating; Forward facing cavity; Shock standoff distance; Cavity flow
• ISSN: 0094-5765; 1879-2030
• DOI: 10.1016/j.actaastro.2020.09.021

Flow control techniques mitigating the aerothermal heating over bodies are essential for long-duration hypersonic flight. The combination technique of a nose cavity with an opposing jet is exhibited promising effects. There is a lacuna of experimental studies on unsteady aspects of the flow and the heat transfer effects within the cavity. In the current study, we investigated the heat transfer variations and nature of shock around a blunt body with a cylindrical and parabolic cavity geometries combined with opposing jet. Experiments are conducted in the hypersonic shock tunnel for a flow Mach number of 6 for an opposing jet pressure ratio of 18. Time-resolved high-speed schlieren imaging and heat flux measurements over the model surface and within the cavity are carried out. The cavity flow is established by verifying the measured heat flux, pressure, and shock oscillation results. The combination technique shows a significant reduction of heat transfer and flow oscillations in comparison to the nose cavity technique. Notably, the parabolic cavity with the opposing jet showed about a 33% reduction of surface heat flux and a 43% reduction in flow oscillations. The substantial increase of heat flux due to the shock interaction is noted on the nose surface for a cylindrical cavity geometry, and such effect was not prevalent in the case of flow with parabolic cavity geometry. •The combination technique is investigated for mitigating the aerothermal heating.•The shock standoff distance is enhanced and the oscillation frequency is reduced.•The parabolic cavity with an opposing jet demonstrated higher heat flux reduction.•The noticeable shock interaction effect is observed for cylindrical cavity case.•The cavity region heat flux is reduced drastically due to the jet injection.