Combustion Characterization for Paraffin-Based Gas Generator with End-Burning

A paraffin-based hybrid gas generator (HGG) with end-burning offers a cost-effective and flow-adjustable gas supply solution for trans-medium systems. To deliver high-quality fuel-rich gas, the combustion dynamics were analyzed theoretically. Using a laboratory-scale HGG with oxygen flow rates of [Formula: see text], firing tests were then conducted to evaluate the combustion characteristics, including ignition, pressure oscillation, regression rate, oxidizer-to-fuel ratio, and combustion temperature. The performance of solid fuels, including polyethylene, pure paraffin, aluminum-loaded paraffin, and paraffin-based fuels, was compared, and the effect of grain structures, including conventional and nested spiral structures, was investigated. The polyethylene fuel grain was tested and served as the baseline. The combustion process with rapid ignition was stable with no observed oscillations. Pure paraffin fuel exhibited superior regression rates that were linearly dependent on oxidizer flux, proving that it is well-suited for HGG. Binders and aluminum additives reduced regression rates by up to 63% and elevated combustion temperatures. Excess aluminum further suppressed regression rates and raised oxidizer-to-fuel ratios. Furthermore, the nested spiral structure enhanced regression rates by 8.6% while preserving the end-burning grain structure. Ultimately, the successful ignition of the water ramjet engine using aluminum-loaded paraffin fuel grains validates the application potential of the HGG.