Mathematical modeling of nonequilibrium combustion processes in a liquid rocket engine

The key problems of safety for Space missions begin with safety, reliability and effectiveness of rocket engines of different types used at different launch stages and orbit corrections. Today, the possibilities for improving chemical rocket engines of traditional types are almost completely exhausted and are limited to minor improvements in energy-mass characteristics. A qualitative leap in the development of engine building can only be achieved through the development and implementation of new types of engines. As unburned fuel in the combustion chamber is a loss of thrust for the engine, the study of droplet combustion and evaporation, in particular, the droplet lifetime, is of fundamental importance in the creation of combustion chambers using atomized liquid fuel in their operation.

In this paper a quasi-stationary model, which describes the evaporation of a single droplet in a gaseous atmosphere, is presented. Since in the numerical implementation the mass flow from the liquid phase to the gas and the heat flux from the droplet to the gas are calculated based on the Peclet number and the droplet surface temperature obtained from the quasi-stationary problem, approximation formulas for these parameters are developed in this paper. As an example, the problems of evaporation of a liquid oxygen droplet in an atmosphere of gaseous hydrogen and a droplet of liquid n-decane in an atmosphere of gaseous oxygen are considered. Formulas for calculation of mass flow and heat flux from liquid phase to gas based on the solution of the droplet evaporation problem are presented. Estimates of droplets lifetime in engine are provided based on developed droplet evaporation models.