Effect of nano-sized aluminum additive on wall heat transfer characteristics of the liquid-fueled scramjet engine

Abstract

Hydrocarbon fuel loaded with highly energetic nanoparticles possesses superior energy density and has great potential to significantly improve scramjet engine performance. The addition of nanoparticles also leads to the increase of combustion temperature and solid deposition on the inner surface of the engine, which affects the wall heat transfer characteristics. In this paper, the stable combustion of JP-10 slurry fuel containing aluminum nanoparticles was achieved in a scramjet engine for the first time, and conspicuous deposition was observed in the engine inner surface. Convective heat transfer models for both pure fuel case and slurry fuel case were established to quantitatively investigate the wall heat transfer characteristics. Calculation results illustrated that the convective heat transfer coefficients of the sensor surface in slurry fuel case are 28.74% higher than that of in pure fuel case, which was the direct reason for the high heat flux results in slurry fuel cases. Further research indicated that the higher wall friction coefficient is the origin of the higher convective heat transfer coefficient. This study found that the rough surface of the deposition in slurry fuel case changes the wall heat transfer characteristics of the engine, resulting in higher heat flux by enhancing the convective heat transfer process.