Hypersonic Synthetic Environment Test Tunnels (HySETT) Program for Propulsion Testing Initiatives Yielding Flight Similitude

There is a need to provide an effective means for extrapolating ground test data to flight, and thus to reduce the time and expense of both ground and flight testing. Current work funded by the U.S. Army Space and Missile Defense Command’s Technical Center has resulted in the Hypersonic Synthetic Environment Test Tunnels (HySETT) program, where hypersonic materials and propulsion research is being conducted. This is being realized via innovations to create clean, non-vitiated hot synthetic air by completely decomposing nitrous oxide into pure oxygen and nitrogen while taking advantage of the generated enthalpy and the minimally produced nitric oxide. Thermal modulation from the mixing of nitrogen to both create the correct air species and meet free stream flight similitude conditions has been successfully achieved. A first test article will be a Dual Mode Ram Jet engine, studied while operating in a scramjet mode, which has also been tested in a combustion air heated facility. This AIAA Aviation Forum paper abstract for the Ground Testing session addresses how to measure and study for comparison the resultant effects on scramjet test performance, since the vitiated air from a combustion air heated facility will differ from inlet-processed ambient air fed to a combustor in actual flight. The price to be paid for “shortchanging” fundamental studies is continuing uncertainty on what might be achieved during actual flight, and the goal of the material beyond this proposed paper is to discuss aspects related to integration of ground testing with computational fluid dynamics and flight testing.