Hypersonic Boundary Layer Transition Experiments in Hypervelocity Ballistic Range G

Hypersonic boundary layer transition impacts vehicles through increased heat transfer and drag, alters a vehicle’s flight path, and is of great concern for hypersonic vehicles. However, it is difficult to predict real world full scale performance with software and ground tests. Transition has long been notoriously difficult to compute with CFD, and ground tests suffer from facility issues like freestream turbulence and noise radiated from wind tunnel walls. Meanwhile, flight tests are the most representative, but also the most expensive, test type. This article presents a unique capability for boundary layer transition testing in a hypervelocity ballistic range, Range G at AEDC, the largest two stage light gas gun in the United States, which can fire models up to 7km/s through quiescent air. Ballistic ranges do not suffer from freestream turbulence problems like conventional or even quiet wind tunnels, but allow tests in free flight at full speed through the real atmosphere (non-vitiated, low turbulence). Transition in an aeroballistic range may occur at high N factors as would be seen in flight. After describing the capability, results are provided for a cone at Mach 10 and compared to others in the literature and to CFD simulations. Hypersonic boundary layer transition in quiescent, non-vitiated air was observed.