Experimental analysis of the flow of exhaust gas in a hypersonic nozzle

摘要

The flow temperature and velocity at various points at the entrance and the exit of a hypersonic nozzle belonging to an air greathing, hydrogen combusting ram jet model were determined. At the wall of the nozzle the pressure was measured and the temperature was extrapolated from measurements inside the material. To characterize the hydrogen/air burner the exhaust gas was analyzed by temperature and species concentrations measurements at atmospheric conditions. The flow velocity, its direction and turbulence were measured by Laser Two Focus (L2F) velocimetry detecting seeded TiO_2-Particles, whose ability to follow the fast expanding exhaust gas was examined experimentally and numerically. Coherent Anti-Stokes Raman Scattering (CARS) was used to measure nitrogen single pulse spectra from which vibrational and rotational temperatures were determined. The flow at the exit of the model nozzle shows a marked thermal nonequilibrium because molecular exchage processes cannot keep pace with the expansion. Due to the thermal non-equilibrium the gross thrust is decreased by about 1