Effect on Shock Train Behaviour of the Addition of a Cavity for Supersonic Intakes
One of the key research areas related to high-speed flight is the ramjet/scramjet propulsion systems. These appear to have the most potential for development into reliable high-speed air-breathing propulsion system. These propulsion systems function by using simple geometries to decelerate the flow through a series of shock waves, a shock train, before entering the combustion chamber. The isolator is an important feature of the propulsion system that is necessary to house this shock train. A significant issue with the operation of ramjet/scramjet engines that this research targets is unstart in isolators. Unstart is the phenomenon that occurs when the isolator experiences an increase in back pressure from the combustion chamber, which itself can be a result of numerous events, resulting in the shock train being expelled out of the propulsion system intake.
This research examines the use of a cavity in the wall of the isolator to delay unstart. However the cavity flow must be actively controlled so as to mitigate the negative impact, drag increase, of the cavity addition. Therefore first the cavity flow dynamics must be examined and the active flow control technique, ns-DBD plasma actuators in this case, demonstrated. This paper presents initial work on the baseline facility flow and the impact that the addition of a cavity will have on it.
The numerical results presented illustrate that the tunnel and cavity model design performs as expected and that the cavity geometry has little impact on the facility flow field as a whole. The experimental work to follow will validate this study and examine the cavity flow field and its control.
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