Aerodynamic Heating

48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition 4 - 7 January 2010, Orlando, Florida

AIAA 2010-991

Reducing Aerodynamic Heating by the Opposing Jet in Supersonic and Hypersonic Flows Isao Tamada1, Shigeru Aso2 and Yasuhiro Tani3 Kyushu University, Fukuoka, 819-0395, Japan The opposing jet is proposed for aerodynamic heat reduction. In this study, the opposing jet has been applied to three nose configurations including the ogive body, the hemispherical nose cylinder and the ogive body with the extended nozzle, to investigate the effects of nose configuration for the opposing jet. Numerical studies have been implemented for the supersonic flow at M∞ = 3.98, and for the hypersonic flow at M∞ = 8.0. Consequently, the opposing jet reduces aerodynamic heating both in supersonic and hypersonic flows. The results also shows that there is a direct correlation between the nose configuration and the thermal protection effect of the opposing jet, and of all three configurations, the extended nozzle model is found to be the most efficient configuration. In addition, detail flow field analysis revealed that distinct correlations exist between shock stand-off distance and the momentum ratio, and between local maximum heat flux and local Reynolds number at the reattachment point for the cases of turbulent flow reattachment. As a conclusion, it has been found that recompressed shock management and local Reynolds number management are essential in order to reduce aerodynamic heating by the opposing jet.

Nomenclature p0∞ p∞ pstag,∞ p0j pj M∞ Mj T0∞ T0j Tw qw Rj Rnose dSF s Re

I

= = = = = = = = = = = = = = = =

freestream total pressure [MPa] freestream static pressure [MPa] stagnation pressure behind the detached shock of the freestream [MPa] total pressure of the opposing jet [MPa] static pressure of the opposing jet at the nozzle exit [MPa] freestream Mach number Mach number of the opposing jet freestream total temperature [K] total temperature of the opposing jet [K] wall temperature [K] heat flux into the wall [W/m2] jet orifice radius [mm] radius of the nose tip [mm] distance from the nose tip to the shock front on the axis[mm] distance from the nose tip along the wall [mm] Reynolds number based on the model diameter

I. Introduction

N designing Reusable Launch Vehicles (RLVs), aerodynamic heating is one of the most important problems to be cared because significantly high aerodynamic heating due to the strong shock waves damages the RLVs body at the reentry stage. Therefore, it is necessary to develop a suitable Thermal Protection System (TPS) for such a challenging circumstance. Thermal protection systems are classified into two categories; passive methods and active methods. Among active methods, the opposing jet has been studied by the previous works1 - 5. Fig.1 shows the general flow field of the opposing jet. Aerodynamic heating reduction is achieved by the cold recirculation region 1

Graduate Student, Department of Aeronautics and Astronautics, Kyushu University. Professor, Department of Aeronautics and Astronautics, Kyushu University, AIAA Senior Member. 3 Associate Professor, Department of Aeronautics and Astronautics, Kyushu University, AIAA Member. 1 American Institute of Aeronautics and Astronautics 2

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