An experimental study has been carried out to investigate the condition of boundary layer in a scramjet nozzle with heat flux measurement. A two-dimensional Single Expansion Ramp Nozzle with contoured ramp was operated under under-expanded condition. Combustion gas of MMH/NTO was fed to simulate the high enthalpy flow (Total temperature of 3100K) in the nozzle. Heat flux to the wallw as measured to evaluate the condition of the boundary layer. Pitot pressure distributions were measured with non-cooled fine niobium probes to verify the estimation method. The niobium probe worked well enough in the high enthalpy flow with sufficient spatial resolution. In consequence, it is confirmed that the boundary layer condition can be estimated with the measured heat flux and core flow conditions obtained with TDK code. With the estimation method, boundary layer conditions in the SERN nozzle with laminar incoming boundary layer was investigated. As results, it is revealed that the boundary layer on the straight cowl become turbulent immediately, whereas the transition of the boundary layer on the contoured ramp was suppressed by the flow acceleration at the ramp corner.
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