Investigation of an intake injected hot-wall scramjet

Injecting fuel on the intake of a scramjet allows the fuel and air to mix before entering the combustion chamber. This allows for a reduction in combustion chamber length, a major contributor to scramjet drag. This investigation aims to check if any combustion is occurring on the intake when the intake wall is hot. Gaseous Hydrogen fuel was injected at an angle of 45 degrees to the freestream approximately halfway along the intake of a two-dimensional scramjet model. The T4 shock tunnel, an impulse testing facility, was used to produce a hypersonic flow with freestream enthalpy of 3.0MJ/kg and Mach number of 6.5. The model was modified such that the intake wall could be heated to temperatures experienced in continuous flight. A pressure rise on the intake or an increase in the initial shock angle after the fuel was injected would indicate the occurrence of intake combustion. Neither of these things was observed in current experiments consistent with no ignition on the intake. The experimental procedure and results are discussed in this paper and compared with theoretical results

Visualisation and measurement of flow on the inlet of an upstream injected supersonic-combustion ramjet

Holographic interferometry has been used to study the flow on the inlet of a supersonic combustion ramjet. Using calculated inflow conditions, the interferograms have been analysed to yield the density of the air flowing through the engine, and to infer the density of the hydrogen fuel injected into the flow

Effects of Upstream Injection on Scramjet Performance Using an Entropy-Based Method

Upstream injection has the potential for increasing the overall performance of a scramjet by reducing the overall length required to complete combustion and, thereby, reducing overall vehicle frictional drug. However, high flow losses will be incurred by injecting a fuel on the inlet where the Mach number is high. A simple overall approach based on entropy generation was used to investigate the effect or flow losses oil overall performance. This showed that the injection flow losses can he quite high for upstream injection when compared with conventional combustor injection. An inviseid analysis of a two-dimensional scramjet at a Mach 10 flight condition found that a significant loss In overall performance of the engine occurs if the bulk of injection is undertaken on the intake. Estimates of viscous effects in a scramjet combustor showed that depending on the reduction of the mixing length achieved in the combustor, the upstream injection flow losses could he substantially recovered, making it an advantageous design option. The analysis technique developed, like similar simple analysis methodologies, provides a useful understanding of the physical processes that influence thrust production and can also be used to quickly evaluate and optimize potential configurations before starting detailed flow-field simulations