Convective and film cooled nozzle extension for a high pressure rocket subscale combustion chamber

Experimental investigations have been carried out to study heat transfer, flow separation, and side loads in a subscale nozzle extension. A Vulcain 2-like nozzle geometry has been tested with combustion chamber pressures up to 13 MPa. A new manufacturing technology has been demonstrated with minimized contour deformation during fabrication. Gaseous hydrogen was used to cool the upper part of the nozzle while flowing through helical, rectangular cooling channels. At a nozzle area expansion ratio of ε = 32 the hydrogen has been injected with supersonic velocity as a film to protect the lower part of the nozzle from the influences of the hot gas. Investigations with varying coolant mass flow rates have shown a stable and safe nozzle operation at real rocket engine-like conditions.