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Effect of back pressure and freestream dynamic pressure on a typical Ramjet engine duct under realistic supersonic inlet condition

Published online by Cambridge University Press:  10 November 2017

R. Saravanan ,
S.L.N. Desikan  and
T.M. Muruganandam
R. Saravanan
Affiliation:
Department of Aerospace Engineering, Indian Institute of Technology Madras, Chennai, India Wind Tunnel Data Division, Aeronautics Entity, Vikram Sarabhai Space Centre, Thiruvananthapuram, India
S.L.N. Desikan*
Affiliation:
Wind Tunnel Data Division, Aeronautics Entity, Vikram Sarabhai Space Centre, Thiruvananthapuram, India
T.M. Muruganandam
Affiliation:
Department of Aerospace Engineering, Indian Institute of Technology Madras, Chennai, India
*
desikan_sln@yahoo.com
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Abstract

The present study investigates the behaviour of the shock train in a typical Ramjet engine under the influence of shock and expansion waves at the entry of a low aspect ratio (1:0.75) rectangular duct/isolator at supersonic Mach number (M = 1.7). The start/unstart characteristics are investigated through steady/unsteady pressure measurements under different back and dynamic pressures while the shock train dynamics are captured through instantaneous Schlieren flow visualisation. Two parameters, namely pressure recovery and the pressure gradient, is derived to assess the duct/isolator performance. For a given back pressure, with maximum blockage (9% above nominal), the duct/isolator flow is established when the dynamic pressure is increased by 23.5%. The unsteady pressure measurements indicate different scales of eddies above 80 Hz (with and without flap deflection). Under the no flap deflection (no back pressure) condition, the maximum fluctuating pressure component is 0.01% and 0.1% of the stagnation pressure at X/L = 0.03 (close to the entry of the duct) and X/L = 0.53 (middle of the duct), respectively. Once the flap is deflected (δ = 8°), decay in eddies by one order is noticed. Further increase in back pressure (δ ≥ 11°) leads the flow to unstart where eddies are observed to be disappeared.

Keywords

RamjetDuct/IsolatorBack PressureShock TrainSupersonic Flow
Type
Research Article
Information
The Aeronautical Journal , Volume 122 , Issue 1247 , January 2018 , pp. 83 - 103
Copyright
Copyright © Royal Aeronautical Society 2017 

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