High speed vehicles incorporating ramjet/scramjet propulsion systems often employ a "shock-on-lip" condition to maximize engine mass capture. Often with this scenario, the forebody-induced shock wave impinges onto the leading edge of the engine cowl. Such an impingement can cause one or more shock-shock interactions that can produce extremely high convective heating rates to the cowl. Due to such interactions, the cowl leading edge region often experiences the greatest convective heating rates found on the vehicle. Earlier research has produced an optimized leading edge generation process applicable for high speed vehicles such as waveriders. In those efforts, Bezier Curves were employed to represent the candidate leading edge cross sectional geometries which were then optimized using a number of cost functions including: minimum peak heating, minimum total heating, minimum drag, and minimum pressure gradient. In the current work, Bezier Curve leading edges have been used in a new optimization process with the goal of reducing the heating to a ramjet/scramjet cowl leading edge by modifying the local shock-shock interaction via geometry modifications of the cowl leading edge. Since these shock-shock interactions are fundamentally an inviscid phenomenon, the Euler equations are used to evaluate candidate configurations as input to a Particle Swarm Optimization algorithm to direct the geometry optimization process. Such optimized cowl leading edge geometries have been generated at a freestream Mach number of 4.6 and have applications to hypersonic vehicles using an air-breathing propulsion system. Results from a single-shock wave based optimization process show up to an 8% reduction in peak pressure on the leading edge.
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