SBIR-STTR Award

Non-mechanical methods for modifying local flowfields on hypersonic vehicles are investigated. These include leading edge shape modifications and wall temperature control. The long range goal is to be able to apply similar techniques to the design of complete optimized aerospace vehicles. This will be done using a combined explicitimplicit time dependent algorithm and the non-linear simplex optimization technique of nelder and mead. Parameters such as the leading edge shape and wall temperature distribution will be varied to find the profiles that maximize the desired functional (l/d). This will be performed at various mach numbers and freestream conditions to observe how the optimum leading edge shapes change, if at all, with mach number and reynolds number.

The National Aerospace Plane or the Hypersonic Transport Plane are expected to encounter very high heating rates especially over the leading edges. Reduction in these rates can be achieved by blunting these leading edges. However this may result in adversely affecting the pressure drag and may also influence transition to turbulence or separation and result in turbulent boundary layer heating. A code has been written that will optimize the shapes of these leading edges to minimize drag while maintaining a constraint for the heat load into the leading edge. A full Navier Stokes code has also been written to study in detail the physics of flows over such shapes. Both the codes have also been exercised extensively and a matrix of various leading edge shapes has been obtained. The same idea of optimizing these leading edge shapes will be applied to the whole configuration of a hypersonic vehicle with different functional optimizations and with various different constraints. In particular such optimization will be done for a vehicle for maximum (l/d), minimum drag, maximum payload/empty weight ratio or minimum heat transfer. It can also be applied for a particular trajectory thus yielding a vehicle optimized for a hypersonic mission. Some of the preliminary results indicate values of (l/d) as high as 7 to 9.