Hybrid Rocket Performance Prediction with Coupling Method of CFD and Thermal Conduction Calculation

Abstract

The final purpose of this study is to develop a design tool for hybrid rocket engines. This tool is a computer code which will be used in order to investigate rocket performance characteristics and unsteady phenomena lasting through the burning time, such as fuel regression or combustion oscillation. When phenomena inside a combustion chamber, namely boundary layer combustion, are described, it is difficult to use rigorous models for this target. It is because calculation cost may be too expensive. Therefore simple models are required for this calculation. In this study, quasi-one-dimensional compressible Euler equations for flowfields inside a chamber and the equation for thermal conduction inside a solid fuel are numerically solved. The energy balance equation at the solid fuel surface is solved to estimate fuel regression rate. Heat feedback model is Karabeyoglu's model dependent on total mass flux. Combustion model is global single step reaction model for 4 chemical species or chemical equilibrium model for 9 chemical species. As a first step, steady-state solutions are reported. c , : specific heat of chemical species i at constant pressure C b : mole number of element C per unit mass of mixture gas ξ : mixture fraction S ξ : stoichiometric mixture fraction i Y : mass fraction of chemical species i r& : regression rate F m & : mass addition from the solid fuel surface w h : enthalpy of the fuel gas evaporating from the surface v h : effective heat of gasification of the solid fuel c Q : heat of combustion per unit mass of mixture gas i w : molecular weight of chemical species i μ : viscosity λ : thermal conductivity α : thermal diffusivity 0 R : universal gas constant t B : thermochemical blowing parameter a B : aerodynamic blowing parameter : ratio of skin-friction coefficient with /without surface blowing : constant parameters in Eqs. (12), (21) c A : preexponential factor s E : activation energy : constant parameters in Eq. (22) : constant parameters in Eq. (25) Subscripts 1 : fuel stream 2 : oxidizer stream