An investigation of the simulation of a solid propellant rocket motor using sublimation of dry ice

Sublimation of dry ice was used to simulate a burning solid propellant rocket motor at the University of Utah in a study of acoustic combustion instabilities. To investigate the possibility of increasing the sublimation rate and to make suggestions for the use of Laser Doppler Velocimetry (LDV), a numerical investigation of the flow and temperature fields and an analytical study of the motion of particles in the simulation chamber were conducted. The continuity, momentum, energy and radiation transfer (flux method) equations for two-dimensional, steady and compressible flow and temperature fields were solved numerically. Flow velocities and temperature distributions for different incident radiation fluxes, surface absorption of the dry ice, and gas scattering albedos were found. High sublimation rates were found to occur due to increasing the incident radiation, the surface absorption or both. A two-dimensional model of moving particles was also developed. This model included a flow velocity gradient and gravity in the vertical direction, and an oscillating flow in the horizontal direction. The experimentally observed "fog layer" was found to be a collection of the particles with radii less than a critical radius r{dollar}sb{lcub}rm c{rcub}{dollar} at a location where the gravity balances the viscous drag caused by the flowing gas. The horizontal motion of particles in the flow can be employed to study the acoustic boundary layer near the subliming surface using the LDV technique. Vertical motion would be very difficult to investigate using this technique due to the very small region where the particles move with the flow and the very small velocities that occur.