The inverse design and performance evaluation of star-shaped hypersonic inlets

The dual mode scramjet is a promising air breathing engine concept that is capable of powering any aircraft in the Mach number range of 3 through 12. This paper describes the inverse design of a coupled forebody-inlet-isolator configuration for possible dual mode ramjet-scramjet engine application. Flow fields derived from the exact solutions of the 2D, Quasi-1D and 1D Euler equations are used as the basis from which stream lines and stream surfaces are created. Moreover, through the coupled use of the exact solutions of shock waves in an ideal gas, and the exact representations of planar and axisymmetric geometric shapes, a series of elementary configurations are developed and analyzed. The design process is accomplished through the use of specially developed subroutines, programmed in Fortran90, to manipulate and assemble these elementary configurations into completed engine configurations. The elementary shapes of interest to this study include the star-shaped leading edges, the caret-shaped inlets, cylindrical combustors, convergent and divergent nozzles, and plug nozzle after-bodies. A design code was developed which delivers as its output; engine configurations along with their performance characteristics.