Temperature and species measurements in a low-thrust hydrogen/oxygen rocket engine

Raman scattering measurements are obtained inside the combustion chamber and near the nozzle exit plane of two experimental models of an onboard hydrogen/oxygen thruster. Temperature, oxygen number density, and water number density data are obtained in the combustion chamber at the injector exit of one thruster. These data show incomplete combustion in the injector section prior to injection of film cooling, and strongly stratified injector temperature and species profiles. Using the measured injector data as input to an axisymmetric Navier-Stokes code does not improve global performance parameter predictions over predictions using fully uniform injector exit profiles. In both cases, performance is underpredicted. Additionally, temperature and oxygen number density data are obtained at the exit plane of the low-area-ratio-nozzle of the second thruster with tbe same injector installed. A comparison of these measured data with analytical predictions that utilize two different sets of input conditions show significant discrepancies for both cases. The Laminar nature of the flow, which the axisymmetric code predicts will occur, precludes sufficient mixing to increase global performance predictions. Three-dimensional modeling of both the injector section and the combustion chamber is needed to obtain more accurate global performance predictions for this thruster.