Experimental investigation of ignition and combustion characteristics of aluminum particle-laden flow

A series of experiments was conducted to study the ignition and combustion characteristics of aluminum particle-laden flows in a propulsion system that used powder as the main fuel. In these experiments, a laminar flame produced by hydrocarbon fuel provided a high-temperature environment for the ignition and combustion of the aluminum particles. The effective oxidant content and flow velocity were adjusted by varying the mass flow rates of three gases (methane, air, and oxygen), and the ignition delay and burning time of the aluminum particles in the particle-laden flow were determined using a high-speed camera. The total time was the sum of the ignition delay time and burning time. The experimental results showed that the ignition delay time could be fitted as a function of the particle diameter, expressed as t_i = a₀ + b₀D; the burning time and total time could also be fitted as functions of the particle diameter, expressed as t_b = aD^b. As the effective oxidant content increased, the burning time decreased significantly, and the total time decreased slightly. The ignition delay time, burning time, and total time were obviously decreased with an increase in the flow velocity of the hot gas. Compared with the effective oxidant content, the flow velocity of the hot gas played a greater role in the reduction of the total time for the aluminum particles in a low-oxidant environment. The agglomeration and separation processes for the burning particles in aluminum particle-laden flows were analyzed in detail.