Particle drag and heat transfer in rocket nozzles

Abstract

An empirical expression for the drag coefficient of a spherical particle in flow regimes such as occur in solid propellant rocket exhausts is presented. In these flows, typical particle Mach numbers will be below 2, and particle Reynolds numbers will range from less than 10 to greater than 100. Also, available heat-transfer relationships are applied to the gasparticle nozzle flow case. The effects of these relationships on computed particle velocities and temperatures are shown. In the cases considered, inertial and compressibility effects dominate for large particles and high chamber pressures, causing the thermal and velocity lags to be less than those predicted under a Stokes flow assumption. However, for small particles and low chamber pressures, rarefaction effects dominate, and the Stokes flow assumption leads to low estimates of particle lag.