Predicting Hybrid Propellant Regression Rate Using Response Surfaces

Abstract

Applied mixture theory allows for estimation of propellant characteristics (such as regression rate or specific impulse) over an extended range of formulations from a limited number of tests. A mixed-oxidizer hybrid system was tested using fuel formulations of 25―30% ammonium perchlorate, 0―5% iron oxide, and 70―75% hydroxyl-terminated polybutadiene fired with gaseous oxygen. Through application of a reduced form of the cubic response equation, functional relationships were developed that correlate fuel composition to regression rate in the form of a three-dimensional response surface. The maximum regression rate was then estimated to occur at approximately 2 % iron oxide and 27.5 % ammonium perchlorate based on the response surface developed from experimental results at an oxidizer flux of 0.3 lb m /in 2 · s (0.211 kg/m 2 · s) and a chamber pressure of 350 psia (2.41 MPa).