Developing a Combustion Model of a Solid Propellant Containing Capsules of Liquid Oxidizer

Abstract

a] 1I ntroductionComparing solid propellant rocket motors and liquid propellant engines, one can clearly see the great advantage in the simplicity of the solid propellant systems. Yeto nt he other hand, one can also notice the inferior energetic performance of solid motors. The relatively poor energetic performance of the solid propellant rockets stems from the poor energetic properties of available solid oxidizers. Over the past few decades efforts have been made in order to find aw ay to improve the energetic performance of the solid propellants, yet with no significant practical result.Several years ago Pelosi and Gany [1-4] published their work on solid propellants augmented by liquid encapsulated oxidizer,s howing significantly higher energetic potential than the conventional solid propellants (up to 20 %i n theory). As part of their work [1] Pelosi and Gany investigated the new concept from different aspects, including encapsulating material, strand burning tests, and combustion modeling. More complicated models were suggested for solid propellants, but not for this novel propellant, which is based on different physical phenomena (liquid oxidizer submerged in as olid matrix).In the current work, the goal is to develop an ew 2D model for the combustion of as olid matrix containing liquid oxidizer capsules within it. The current model also takes into consideration the changes over time of the nature of the combustion process. 2T he ModelLittle research has been done so far in the subject of combustion of liquid oxidizer droplets contained in asolid polymeric matrix. The combustion of as mall size liquid oxidizer droplet within as olid fuel matrix is similar to the combustion of classic solid composite propellant. The well-known BDP model [5][6][7] is a2 Dm odel combining the physical aspects of the process, based on the GDF model [8],a nd the chemical kinetics aspects.This research objective is the development of at ime dependent 2D model, in contrast to the 1D time averaged model that was introduced by Pelosi and Gany several years ago [1][2][3][4].T he current model deals with ap ropellant consisting of ac ontinuous solid matrix containing liquid droplets/capsules of oxidizer,w hich are modeled as cylinders with height equal to diameter,i no rder to simplify the calculations. The current model deals with the sub-critical pressure range, where the oxidizer undergoes three stages in the combustion process:Abstract:Acombustion model of as olid propellant containing liquid oxidizer capsules was developed. The model is based on the combustion cycle of au nit cell, an oxidizer droplet surrounded by the adjusting amount of binder. Three combustion stages are considered:( 1) binder decomposition parallel to oxidizer heating up to boiling temperature, (2) simultaneous binder and oxidizer gasification, and (3) gasification of the remaining condensed phase species. Simple global kinetics are assumed for the gas phase reactions and binder decomposition abiding Arrhenius law,a nd boiling process for the oxidizer abiding...