Combustion characteristics of Al/B loaded Gel fuel droplets under high temperature and pressure
Mengxiong Li, Chuxiang Sun, Qingyu Li, Qingchun Yang, Hongxin Wang, Xu Xu
Abstract
This research investigates the combustion behavior of aluminum and boron loaded gel fuel droplets (10–20 wt%) under high-temperature and high-pressure conditions. High-speed and color imaging captured the combustion process. The addition of gellant induces micro-explosions that enhance the burning rate; however, increasing particle concentration weakens this effect. At high concentrations, early particle shell formation hinders gel layer development, suppressing micro-explosions. Both micro-explosions and particle shells promote liquid-phase combustion. At low concentrations, micro-explosions dominate the enhancement, while at high concentrations, larger, early-formed particle shells are the primary contributor. Increasing ambient pressure reduces micro-explosion intensity but shortens ignition delay and raises the burning rate. Under high pressure, weak micro-explosions offer less enhancement and lead to larger particle agglomerates. Aluminum and boron gel droplets show similar liquid-phase behavior, but differ in particle combustion: aluminum ignites under all conditions, while boron requires higher pressures. The combustion process of high-concentration gel droplets under elevated conditions is divided into four stages: Stable Combustion, Particle Shell Formation, Particle Agglomerate Ignition, and Molten Particle Combustion. This staged model emphasizes the dominant role of particle shells, with minor contributions from micro-explosions.