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This thesis sets out to study the delivery of fuel to a scramjet combustor by the use of injectors placed on the intake. This method of injection is a means of reducing the combustor's viscous drag but potentially suffers from the flaw of inducing combustion on the intake due to the high temperature of the boundary layer. This investigation is primarily experimental. A two dimensional scramjet is used, and the effects of injecting fuel on the intake are observed by means of shadowgraph and wall pressure measurements. These experiments were undertaken in the T4 shock tunnel at the University of Queensland. Existing theoretical work is shown to be in good agreement with the new scramjet results reported here. It is shown experimentally that the thrust generated by the scramjet is independent of the fuel injection angle between 25° and 90° to the flow. Experiments using a cold wall scramjet with freestream enthalpies of 3.0 MJ/kg show no evidence of burning on the intake but burning is observed in the combustion chamber. Theoretical predictions of the temperature profile on the intake indicate that this finding is independent of model wall temperature between 300 and 800K. It is concluded that no significant burning occurs in the intake and that fuel injection from the intake is a viable means of delivering fuel to the combustion chamber in a scramjet.
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