Particle velocity on solid-propellant surface using x-ray real-time radiography

In a solid rocket motor using aluminized composite solid propellant and submerged nozzle, two-phase flow needs to be investigated by both experiment and computation. The boundary conditions for the ejecting particles constrain their trajectories; hence, these affect the two-phase flow calculations and, thus, significantly affect the evaluation of the slag accumulation. A new method to determine the velocities of particles on the solid-propellant surface was developed, which is based on the x-ray real-time radiography (RTR) technique and coupled with the two-phase flow numerical simulation. A method was developed to simulate the particle ejection from the propellant surface. The moving trajectories of metal particles in a firing combustion chamber were measured by using the RTR high-speed motion analyzer. Image-processing software was also developed for the RTR images so that the trajectories of particles could be obtained. Numerical simulations with different propellant-surface boundary conditions were performed to calculate particle trajectories. By comparing the two trajectories, an appropriate boundary condition on the propellant surface was inferred. The present method can be extended to study the impingement of particles on a wall and other related two-phase flows.