A new system design tool for a hybrid rocket engine

A new system design tool for the simulation of a full hybrid rocket engine is developed in this article. This tool enables to simulate the behaviour of the engine at different conditions/configurations in several minutes from a desktop computer by keeping a balance between accuracy and computation time. This makes its use especially attractive for the pre-design phases of the engine. The main components of the hybrid rocket engine from our laboratory -characterized by a catalytic injection of the oxidizer-, are modelled and implemented in the tool: the feed/injection sub-system through 0-D models of a mass flow rate regulator and a catalyst; the combustion chamber, with a 1.5-D model; and the nozzle through a 1-D model. An iterative method is employed to reach the convergence of pressure in the combustion chamber between these sub-systems. The corresponding set of equations is solved by a Newton–Raphson technique. Seven experiments performed on our lab-scale engine were used to validate the system design tool. In five of the simulations, the relative differences of the main physical quantities with the experiment were below 30%, being the largest errors found in the fuel regression rate and mixture ratio. The best agreements with the experiments were retrieved for the cases with the largest oxidizer mass fluxes (above 230 kg/m2/s) and mixture ratios closest to stoichiometry, defining thus, the range of applicability of the system design tool. The results presented in this article were issued of a Ph.D. thesis.