Jan Martinez Schramm  , Sebastian Karl  , Klaus Hannemann and Hiroshi Ozawa

DOI Number XXX-YYY-ZZZ

Conference Number HiSST 2018-2190880

A small scale flight experiment (SSFE) configuration powered by a Mach 8 scramjet was designed within the European Commission co-funded project Long Term Advanced Propulsion Concepts and Technologies (LAPCAT) II. The main objective of the test campaigns conducted in the High Enthalpy Shock Tunnel Göttingen (HEG) of the German Aerospace Center was to demonstrate that the numerically predicted positive aero-propulsive balance of the SSFE could be confirmed experimentally. The experiments were performed for a flight condition of Mach 7.4 at 27 km altitude. The positive aero-propulsive balance could be demonstrated utilizing the free flight force measurement technique based on optical tracking. Additionally, pressure and heat flux measurements were conducted on the intake, in the combustion chamber and on the thrust nozzle. Subsequent comparison to numerical predictions led to the conclusion, that one reason for the observed discrepancies could be the state of the hypersonic boundary layer on the intake. For the design, a fully turbulent boundary layer was assumed since no direct evidence of the real behavior was available. Therefore, the laminar to turbulent boundary layer transition process on the intake was studied in the framework of the development of an ultra-fast temperature sensitive paint (TSP) technique in HEG. The necessary prerequisites, which have to be fulfilled to apply TSP in a free piston driven shock tunnel, and the experimental setup for the scramjet intake measurements as well as the data evaluation procedure with special focus on the accuracy of the TSP technique, are discussed. The complex boundary layer transition process on the intake is characterized and the transition line is determined based on a combined experimental and numerical evaluation procedure. Further, information on the transition behavior extracted from this analysis is used as input for a numerical study using a Reynolds stress based turbulence model. The difference between the design assumption of a fully turbulent boundary layer and the transitional case is highlighted.

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In Categories: Boundary Layer Control, HiSST 2018, Hypersonic Aerodynamics, Testing and Evaluation, Thermal and Energy Management Systems
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