Viscous optimized hypersonic waveriders designed from flows over cones and minimum drag bodies

A series of "viscous optimized" waveriders is designed from general axisymmetric flow fields--most notibly, flow fields over minimum drag bodies. These configurations represent the next logical step in an ongoing program of research on the design of hypersonic waveriders at the University of Maryland. In previous work at Maryland, inviscid conical flow was used exclusively in the design of waveriders. These conical flow waveriders predict high values of lift/drag, higher than the values based on experience from other hypersonic configurations. The present work allows the design of waveriders from almost any axisymmetric flow field--although the present results focus on the inviscid flows over cones, and 3/4 and 1/2 power-law bodies. The power-law bodies represent minimum wave drag bodies. A space-marching, finite-difference code is used to generate the axisymmetric flow field. The undersurface of the vehicle is carved out as a stream surface of this axisymmetric flow field, whereas the upper surface is assumed to be a freestream surface. The detailed viscous effects are included within the optimization process, using a simple reference temperature method. Results obtained using the reference temperature method are within 10% of results obtained using a more complex integral boundary layer method even at high hypersonic Mach numbers. Boundary layer transition is predicted using a correlation of the local transition Reynolds number with Mach number. A non-linear simplex method is used to optimize the waveriders for either maximum L/D or for minimum total drag.; The waveriders designed from the flow fields over minimum drag bodies have values of L/D that are equivalent to, or better than, values obtained for conical flow waveriders. The best optimum (highest L/D), for a given Mach number and flow generating body, is obtained when the wave drag and the skin friction drag are nearly balanced. Distinctly different configurations result depending on whether one optimizes for a hypersonic cruise configuration (maximum L/D) or for a hypersonicaccelerator configuration (minimum drag). The nature of the boundary layer and the geometric constraints have a strong influence on the outcome of the optimization.