Modeling of Metallized Solid Fuel Hybrid Propulsion System

Abstract

The most commonly used Hybrid Rocket Motor (HRM) consists of an inert pure solid fuel (SF) with liquid or gaseous oxidizer. Until now, the regression rate of SF in HRM has typically been an order of magnitude lower than that of solid propellant motor. The objective of this paper is to investigate the possible enhancement of regression rate by addition of metal powder. This may guide to effectively design and produce high performance HRM for specific applications. A mathematical model has been introduced and a computer program is built to describe metalized SF regression rate and HRM performance. A series of experimental tests using a small scale HRM employs Polyethylene (PE) with Aluminum (Al) metal powder additive (2.5, 5, 7.5, 10, 12.5, and 15% by mass) as SF and gaseous oxygen (GO2) as oxidizer to evaluate the metalized SF regression rate and HRM performance. The measured experimental data are compared with results obtained from theoretical computation. The comparison shows good agreement, which proves the validity of the developed program, since the maximum error noticed was generally less than 10%. An addition of up to 7.5% Al powder increases the regression rate by about 90% and the chamber pressure by nearly 40% as compared to classical HRM with no additives.