Analysis of Heat-Transfer Effects in Rocket Nozzles Operating with Very High-Temperature Hydrogen

Abstract : An analytical technique suitable for& the solution of complex energy transfer problems involving coupled radiant and convective energy transfer is developed. Solutions for the coupled axial wall energy flax distribution in rocket nozzles using hydrogen as a propellant are presented. Flow rates and temperatures studied are near those forecast for gaseous-core nuclear-propulsion systems. Parameters varied are nozzle shape, inlet propellant temperature, mean reactor cavity temperature, and nozzle wall temperature level. The effects of variation of the propellant radiation absorption coefficient with pressure, temperature, and wavelength are presented, and real property variations are used where they appear to be significant. Comparison is made to a simplified, coupled solution using a modified second-order one-dimensional diffusion equation for the radiative transfer. At the temperature levels assumed, radiative transfer may account for a greater portion of the total energy transfer over important portions of the nozzle, and its effects cannot, therefore, be neglected. Extreme energy flaxes (near 3XlO to the 8 Btu/(hr)(sq ft)) are observed for certain cases, and this implies that new nozzle cooling techniques must be developed.