Preliminary Design Methodology for Hypersonic Engine Flowpaths

A new scramjet engine model, called MASIV, has been developed for control-oriented applications. To reduce computational time, each component models the pertinent physical mechanisms while reducing the spatial dimensionality of the problem. New aspects of MASIV include real-gas dissociation, finite-rate chemistry, a new fuel-air mixing model, an assumed-PDF turbulent combustion model, and interactions of shocks and expansion waves. Strategies for designing 2D scramjet inlets are discussed. One approach is optimize an inlet for a single flight condition. When an inlet designed in this way is at the design condition, all shocks intersect at the cowl leading edge. This optimizes performance at the design condition, but for o-design operation losses are highly sensitive to changes in Mach number and angle of attack. An improved inlet design is described that operates eciently over a range of conditions. In addition, the scramjet combustor also is analyzed to show the eect of pressure distribution on thrust performance for five fuel injection locations. Results suggest general design guidelines, one of which is that injectors should be placed as far upstream as is practical, so that most of the combustion is completed upstream of the nozzle.