Numerical simulations of aerospace propulsion nozzles are very complex due to the necessity to simultaneously handle flow acceleration, momentum heat-transfer rates, surface roughness, temperature-dependent air properties and streamwise density variations due to the compressible character of the flow. To provide an overview for a multitask consideration of the propulsion-nozzle flows, a new computational model that integrates the axi-symmetrical continuity, the momentum and the energy equations has been developed. Numerical experiments were performed with various nozzle geometries, inlet-boundary conditions, with the combined handling of the surface heat flux and roughness conditions. The computations indicated that the input and loss power values of the propulsion nozzle increase with higher inlet stagnation pressures and decrease with higher nozzle convergence half angles and surface heat flux. The ratio of the loss to the input power was found to be independent of the heat flux; however it decreases linearly with an increase in the convergence half angles. (c) 2007 Journal of Mechanical Engineering. All rights reserved.