| A model to analyze the unsteady, multi-dimensional, turbulent flows in the head-end, star slot section of a solid rocket motor during ignition transients is developed. This investigation examines the fluid dynamic aspects of the starting transient, and attempts to simulate the time dependent interactions between the igniter plume flow, convective heat transfer to the propellant, mass injection from the surface of the burning propellant grain, and flame spreading. A finite-difference solution of the unsteady, compressible, full Navier-Stokes equations, along with a two-equation k-{dollar}varepsilon{dollar} turbulence model, is performed utilizing the MacCormack explicit, predictor-corrector technique. The model is validated by comparing computed results with known experimental data. The prediction of the ignition transient sequence from the onset of igniter flow to complete ignition of the head-end, star slot section of a solid rocket motor is performed for three different cases: a single-port igniter and two multi-port igniters, with angles of inclination of the port axis of symmetry to the motor centerline of 22.5{dollar}spcirc{dollar} and 45{dollar}spcirc{dollar}, respectively. The solution shows the temporal development of the flame front and the associated velocity field, and indicates that the multi-port igniters provide a faster ignition transient of the head-end section than the single-port igniter, with shorter ignition lags and higher flame spreading rates. |
