Infrared Thermography and Pitot Pressure Measurements of a Scramjet Nozzle Flowfield

An experimental study on single expansion ramp nozzle flows was carried out at a freestream Mach number of 7 in the hypersonic wind tunnel in Cologne, Germany. The Reynolds number in the tunnel flow was varied to study the performance of the scramjet nozzle at different flight altitudes. The effects of different nozzle pressure ratios were investigated and compared by pitot pressure measurements and schlieren photographs. The temperature distribution on the surface of the single expansion ramp was measured by using infrared thermography. The Stanton number and heat-flux distribution on the surface were determined from measured surface temperature history. Here, it can be seen that the external flow does not influence the temperature distribution. The temperature and Stanton number distribution, however, do depend on the nozzle pressure ratio. A pitot rake was used to measure the pitot pressure distribution in the nozzle wake and characterize the interaction between the nozzle and external flow, as well as the influence of the temperature on the nozzle flow. This showed that the nozzle core flow is independent from the external flow conditions, but the interactions between the two flows are highly dependent. The data obtained by the different measurement techniques gave insight into the properties of single expansion ramp nozzle flows.