Hot Plume Testing Facility Cologne (HPTF): Demonstration, Qualification and Exploration Tests with the Water-Cooled Penn-State-like Burner HOC2

Abstract

The blow-down-type wind tunnel Vertical Test Section Cologne (VMK) of the German Aerospace Center (DLR) in Cologne is used for aerothermodynamic testing of spacecraft and missiles, as well as for the flight qualification of components up to Mach 3.2. In 2017, the wind tunnel was upgraded by integrating a hydrogen and oxygen supply facility forming the newly developed Hot Plume Testing Facility (HPTF) primarily for the generation of hot combustion gases in the wind tunnel environment. Hot combustion gases are a requirement for flight duplication for applications such as space transportation systems, ram- and SCRamJets. For the demonstration, qualification and exploration of the facility, tests with a capacitively cooled combustion chamber have been executed for an operating range accessible to that design. To extend the operating range, the design of the existing combustion chamber was modified to accommodate water-cooling. This combustion chamber named HOC2 was used for testing for extended testing times (t > 40 s) at combustion chamber pressure levels above 6.0 MPa close to stoichiometric mixture ratios. Apart from the characterization of the facility, the experiments provide insights into the development of wind tunnel model integrated combustion chambers. Research questions regarding the injector geometry, combustion chamber stability, and cooling requirements are addressed. These results are used to outline the currently-explored operational range of the HPTF. Further, the results expand the knowledge on the design of wind tunnel models with integrated combustion chambers to duplicate conditions of space transportation systems in flight. This capability to conduct wind tunnel tests with realistic mixture ratios close to stoichiometric conditions is not yet existent in Europe to that scale.