Hypersonic Laminar-Turbulent Transition Experiment Design: From wind tunnel model definition to MDOE Approach.

This paper describes the Design of Experiment to study the laminar-turbulence transition phenomenon in Hypersonic regime on a 3-deg half-angle sphere-cone model. The huge number of factors (as bluntness, distributed roughness, Mach and Reynolds numbers, etc.), that affect the laminar-turbulent transition, makes this phenomenon very complex and expensive to study with a typical experimental approach. As consequence, a Modern Design Of Experiment approach was adopted to develop highly efficient experiment designs yielding results to within a specified accuracy and, at the same time, saving resources in terms of costs and time consuming. Preliminary numerical analyses have been performed on several sphere-cone geometries for several values of the Mach and Reynolds numbers in order to define the basic requirements for the experimental test campaign. Moreover, an innovative and simple rough nose realization methodology definition was an essential step of the experiment design phase, as it conferred to MDOE technique, the mandatory freedom in terms of number of noses and values of roughness selection