Combustion Behavior of Hydrocarbon/Boron Gel-Fueled Scramjet
Yushu Jin, Xu Xu, Qingchun Yang, Suyi Dou, Xu Wang, Qingfei Fu, Lun Pan
Abstract
Using energetic boron particle as an additive to hydrocarbon gel fuels is an effective method to improve the performance of a scramjet/ramjet system. To evaluate the combustion characteristics and application performances of boron-containing gel fuel in an airbreathing scramjet, a comprehensive experimental study was carried out on the injection, atomization, combustion, solid deposition, and wall heat flux of JP-10 wt % B gel fuel and JP-10 gel fuel in a directly connected scramjet combustor. The simulated air entered the combustor at a Mach number of 2 and a total temperature of 1700 K, while the gel-fuel equivalence ratio varied between 0.6 and 1.0. The results demonstrated that the volume-controlled fuel supply system driven by electric motor and gas-assisted injector can realize the stable injection and efficient atomization of highly viscous non-Newtonian gel fuels. Two optical diagnostic methods proved that the boron-containing gel fuel is capable of achieving stable combustion in the scramjet combustor with single-cavity configuration. Based on the measurement of wall pressure along the flowpath, the combustion efficiency of the two gel fuels at different equivalence ratios was calculated using the one-dimensional impulse analysis method. The combustion efficiency of the JP-10 + B gel fuel is 3.51% higher than that of the JP-10 gel fuel, while the addition of boron particles increases the density specific impulse of gel fuel by 8.42%. These results indicated that the addition of boron particles indeed showed a positive effect on combustion characteristics and engine performance. Finally, the wall deposition phenomenon found in the combustion of boron-containing gel fuel was introduced, and the reason for about 22% increase in wall heat flux caused by the addition of boron particles was simply analyzed.