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Simulations of a low-boom, axisymmetric, external compression inlet

Published online by Cambridge University Press:  27 January 2016

T. Coyne
Affiliation:
University of Chicago, Chicago, USA
E. Loth*
Affiliation:
Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, USA
J. Koncsek
Affiliation:
Seattle, USA
D. Davis
Affiliation:
Aerojet (currently at NASA GRC), Cleveland, USA
T. Conners
Affiliation:
Gulfstream Aerospace Corporation, Savannah, Georgia, USA
D. Howe
Affiliation:
Technical Fellow, Gulfstream Aerospace Corporation, Savannah, USA

Abstract

Computational simulations have been used to study a new low-boom, axisymmetric, external compression supersonic inlet with an on-design Mach number of 1·7. The inlet incorporates a relaxed compression surface with a near-zero cowl angle to help reduce external oblique shock waves due to spillage and cowl geometry. To reduce mechanical complexity the inlet is designed with zero-bleed. To understand the impact on performance and shock overpressure caused by the inlet itself, several throat and diffuser designs were simulated. The computations utilised a Reynolds-averaged Navier-Stokes code. Inflow properties were held consistent with the operational characteristics of the NASA GRC 8′ × 6′ Supersonic Wind Tunnel (SWT) for experimental testing of the inlet of Mach 1·67 at a Reynolds number of 5·4 × 106. Stagnation pressure recovery performance for the baseline condition exceeded 94% at design mass flow rates, and reduced only slightly with increases in Mach number (consistent with theoretical predictions) and extension of cowl position. The simulations also showed that the relaxed compression surface combined with the near-zero cowl angle helps to significantly reduce external oblique shocks This is partly due to the reduced inlet spillage in combination with a reduced overall turning angle placed on the free-stream flow relative to the cowl shape.

Type
Research Article
Copyright
Copyright © Royal Aeronautical Society 2013 

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