SCRAMJET THRUST MEASUREMENTS IN A SHOCK TUNNEL USING A COMPLETELY FREE-FLIGHT AND A RESTRAINED FORCE MEASUREMENT SET-UP

Abstract

Optical tracking based free-flight force measurements were conducted in the High Enthalpy Shock Tunnel Göttingen (HEG) to determine the thrust increment generated by a gaseous hydrogen fueled complete scramjet engine flow path at M = 7.4 and simulated 28 km flight altitude. This engine represents the propulsion unit of a proposed Small Scale Flight Experiment (SSFE) configuration. Optical tracking in conjunction with the free-flight technique was so far successfully applied in shock tunnels utilizing small wind tunnel models to study external aerodynamics. Here it was applied to a large scale and heavy wind tunnel model implicating new challenges regarding the model set up as well as the optical tracking procedure. Two test modes were utilized. A fully free-flying mode, where the model is not restrained during the test time and a restrained mode, where the model keeps attached to the threads which are covered during the tests. Both modes are compared and the results are discussed.