Experimental study of forward-facing cavity with energy deposition in hypersonic flow conditions

Sudarshan, B and Deep, S and Jayaram, V and Jagadeesh, G and Saravanan, S (2019) Experimental study of forward-facing cavity with energy deposition in hypersonic flow conditions. In: Physics of Fluids, 31 (10).

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Abstract

Controlling nose surface peak heat fluxes is crucial to the design of hypersonic vehicles. In this study, we report a novel technique of convective heat flux reduction on the nose surface of a spherically blunted cone by employing a forward-facing cavity combined with heat energy deposition inside the cavity. The heat deposition is achieved by the exothermic reaction of a chromium film coated on the cavity surface. The experiments are performed in hypersonic shock tunnels using air as the test gas at free stream stagnation enthalpy conditions of 2.2 ± 0.08 MJ/kg (H1), 3.2 ± 0.018 MJ/kg (H2), and 5.4 ± 0.02 MJ/kg (H3), for a geometry of cavity length to diameter ratio of 1. Schlieren images of the flow are captured using a high-speed camera and a high-power pulsed diode laser light source. The surface heat flux measurements were performed using calibrated platinum thin film sensors. We observed that the heat deposition altered the cavity flow field significantly by lowering the flow oscillation frequency and increasing the shock standoff distances with higher oscillation amplitudes. The overall surface mean heat flux reduction is increased from ≈13% to ≈49% compared to the blunt body geometry, whose nose radius is 30 mm and enhanced with reference to the cavity without heat deposition from ≈15% to ≈35%. Chromium film surface reactions are studied using X-ray Photoelectron spectroscopy, and the results confirm that the exothermic surface reactions of the Cr thin film are attributed to the formation of oxides and nitrides of Cr.

Item Type:	Journal Article
Publication:	Physics of Fluids
Publisher:	American Institute of Physics Inc.
Additional Information:	The copyright for this article belongs to American Institute of Physics Inc.
Keywords:	Deposition; Facings; High speed cameras; Hypersonic flow; Hypersonic vehicles; Light sources; Metallic films; Oscillating flow; Surface reactions; Thin films; X ray photoelectron spectroscopy, Energy depositions; Flow oscillations; Oscillation amplitude; Platinum thin film; Pulsed diode laser; Stagnation enthalpy; Stand-off distance (SoD); Surface heat fluxes, Heat flux
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering) Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	05 Jan 2023 09:10
Last Modified:	05 Jan 2023 09:10
URI:	https://eprints.iisc.ac.in/id/eprint/78777

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