EVOLUTION OF INTERNAL FLOW IN A SOLID ROCKET MOTOR WITH RADIAL SLOTS

A study of the internal how in a solid rocket motor with radial slots was conducted via numerical solution of Reynolds-averaged Navier-Stoke s equations, The main objective of this effort was to study the intern al how structure with regard to ifs implications on the how-induced in stabilities, Two different radial slot designs were considered under t he present study. The first configuration considered represents a conv entional radial slot design, wherein the forward and the aft faces of the slot are in planes normal to the motor axis. The second radial slo t design studied under this effort was designed with the slot faces cu rved toward the aft direction and a contoured aft corner, The contoure d slot design was aimed at providing a better aerodynamic flow-path to turn the slot flow toward the nozzle, thereby resulting in a flowfiel d that would be less susceptible to instabilities. The computed result s obtained for conventional slot design indicate that there is how sep aration near the aft edge of the slot. The simulation results obtained for the contoured slot design indicate that this design is quite succ essful in eliminating the aft-corner how separation and, results in a more stable flow structure, The internal flow calculations for the mot or with this contoured slot design were conducted at several different web-burn conditions. These simulations show that the evolution of the flowfield structure in the slot cavity with the web burn can vary sig nificantly depending upon the axial location of the slot. The flowfiel d in the aft slot cavity of the three-slot motor studied under the pre sent effort evolved initially to resemble a driven cavity how At subse quent burn-back geometry, the flow in this slot evolved to resemble th e how over a backward facing step, The flow structure in the forward a nd the center slots of this motor shows no similar evolution.