Introducing metal oxide as solid oxygen carrier for energy release enhancement of boron suspension fuel

Abstract

Boron (B) suspension fuel is a novel high-density fuel for aerospace propulsion. However, it suffers from significant incomplete energy release of B during combustion, which seriously restricts its practical application. This study focuses on the key causes of this problem, insufficient oxygen supply, and proposes to introduce metal oxides (MOx) as solid oxygen carriers to form B-MOx and replace pure B to enhance the energy release characteristics of B suspension fuel. TG-DSC analysis is conducted to sort out CuO as the optimal additive for B oxidation enhancement and its enhancement mechanism is analyzed with thermal equilibrium calculation. It was found that CuO could generate active O atoms through two-step reduction, thus achieving efficient oxygen supply for B and reduce its initial reaction temperature from 810 °C to 661.7 °C with an optimal B-CuO ratio of 1:1. CO2 laser ignition experiment and combustion residue analysis are conducted to analyze the combustion characteristics of B-CuO/JP-10 suspension fuel. Compared with original B/JP-10 suspension fuel, B-CuO/JP-10 suspension fuel presents much higher combustion intensity with local explosion after ignition, and a second stage of intensive energy release is realized with the reignition and explosion of solid agglomerate. The oxidation of JP-10 and B are enhanced with no incomplete oxidation product found in the residue. The enhancement mechanism of CuO on B suspension fuel is proposed including the generation of active radical, efficient internal oxygen supply and enhanced external oxygen supply.