Calculations of the Internal Ballistics of a Hybrid Rocket Engine

Abstract

This paper discusses the modelling of hybrid rocket engines. The topics also included the issue of modeling the propagation of grain geometry during combustion, which is an important problem both from the perspective of modeling the operation of hybrid engines and rocket engines using solid propellant. The motivation to undertake the analyses described here was  the  desire to increase  the accuracy and  effectiveness of the simulations of hybrid engines carried out as part of the work of the Students’ Space Association (SKA) with the use of the Rocket Propulsion Analysis Tool (RPAT) program developed as part of the Association's work in the MATLAB language. The models of linear  combustion velocity  of the fuel grain in a hybrid engine obtained from the literature analysis were validated here. The validation was based on measurement data obtained during the static operation test of the Basilisk hybrid engine designed to propel the Twardowsky rocket. This engine uses HTPB (hydroxyl-terminated polybutadiene) as  fuel, and nitrous oxide (N2O) as an oxidizer. A comparison of  the available methods for modeling the propagation of the grain burning front was also carried out, which allowed the selection of the fast march method as potentially suitable for the application under consideration.