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Effects of hydrogen–air non–equilibrium chemistry on the performance of a model scramjet thrust nozzle

Published online by Cambridge University Press:  03 February 2016

R. J. Stalker
Affiliation:
Division of Mechanical Engineering, University of Queensland, Brisbane, Australia
N. K. Truong
Affiliation:
Division of Mechanical Engineering, University of Queensland, Brisbane, Australia
R. G. Morgan
Affiliation:
Division of Mechanical Engineering, University of Queensland, Brisbane, Australia
A. Paull
Affiliation:
Division of Mechanical Engineering, University of Queensland, Brisbane, Australia

Abstract

Two aspects of hydrogen-air non-equilibrium chemistry related to scramjets are nozzle freezing and a process called ‘kinetic afterburning’ which involves continuation of combustion after expansion in the nozzle. These effects were investigated numerically and experimentally with a model scramjet combustion chamber and thrust nozzle combination. The overall model length was 0·5m, while precombustion Mach numbers of 3·1±0·3 and precombustion temperatures ranging from 740K to 1,400K were involved. Nozzle freezing was investigated at precombustion pressures of 190kPa and higher, and it was found that the nozzle thrusts were within 6% of values obtained from finite rate numerical calculations, which were within 7% of equilibrium calculations. When precombustion pressures of 70kPa or less were used, kinetic afterburning was found to be partly responsible for thrust production, in both the numerical calculations and the experiments. Kinetic afterburning offers a means of extending the operating Mach number range of a fixed geometry scramjet.

Type
Research Article
Copyright
Copyright © Royal Aeronautical Society 2004 

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