Modeling of solid particle interaction in a high-velocity hot gas stream

Abstract

A detailed mathematical model for predicting ignition characteristics of an accelerated solid-particle parcel of various loading ratios in the gas flow behind shock waves in an actual motor environment is developed using the moving coordinate system. The model incorporates the effect of evaporation, radiation, and loading ratio on the drag and heat transfer to the solid particles and their effect on the ignition delay period. Moreover, it considers momentum wall losses, heat transfer to the wall, and viscous work done by the wall on the fluid. The present model responds to the shock wave intensity, loading ratio, and metal powder size. The solid particles investigated include magnesium, aluminum, and solid propellant. A parametric study has been carried out to study the factors affecting the ignition delay of metal powder. Results show that for shock intensities ranging between 25 and 4, magnesium and aluminum powder of sizes 30 and 14-μm are ignited by the thermal explosion mechanism. Small particles have also been found to accelerate up to the induced gas velocity behind the shock wave, resulting in higher ignition delay periods. Results have also been validated from experimental data in the literature, and reliable chemical kinetic constants have been deduced for Mg and Al, respectively: A =2.4×10 4 and 1×10 6 cm 2 / s , E =2.0 ×10 2 and 3.7×10 2 kJ/mole, and Q =4.7×10 4 and 1.67×10 4 kJ/kg.