Preliminary investigation of paraffin-based fuel combustion in solid fuel scramjet

Abstract The purpose of this paper is to study the combustion characteristics of paraffin-based fuel grain in a supersonic flow, as a preliminary to investigate its potential as fuel in a solid fuel scramjet. Paraffin-based fuel, due to its high regression rate, will pyrolyze more fuel gas in the solid fuel scramjet during the same period of time, indicating that its application would increase the combustion efficiency of the solid fuel scramjet. Based on the strength and energy density of the fuel, the paraffin-based fuel applied herein consists of 45% paraffin, 40% aluminum powder, and 15% hydroxyl-terminated polybutadiene. Due to the lack of regression rate law of the paraffin-based fuel, a regression rate model for the paraffin-based fuel was established. Experiments were carried out on the ground dedicated connected-pipe static test facility to verify the correctness of the model. The numerical results are in good agreement with the experimental results. The results show that in solid fuel scramjet, the regression rate of paraffin-based fuel is 2–3 times that of poly-methyl methacrylate fuel. The total combustion efficiency of a paraffin-based solid fuel scramjet increases with the combustion process.