Howard J. Gibeling

Navier-Stokes analysis of solid propellant rocket motor internal flows

motor chamber is injection driven, i.e., all of the gas in the domain enters via injection at the walls. The calculation procedure incorporates a two-equation (A>e) turbulence model and utilizes a consistently split, linearized block-implicit algorithm for numerical solution of the governing equations. The code was validated by comparing computed results with the experimental data obtained in cylindrical-p ort cold-flow tests. The agreement between the computed and experimentally measured mean axial velocities is excellent. The axial location of transition to turbulent flow predicted by the two-equation (k-e) turbulence model used in the computations also agrees well with the experimental data. Computations performed to simulate the axisymmetric flowfield in the vicinity of the aft field joint in the Space Shuttle solid rocket motor using 14,725 grid points show the presence of a region of reversed axial flow near the downstream edge of the slot. Calculations were also performed for two cases involving asymmetric three-dimensional flow in the vicinity of the aft field joint in the solid rocket motor using 721,525 grid points to estimate circumferential velocities and pressure gradients at the joint.

Calculation of particle trajectories in solid-rocket motors with arbitrary acceleration

The particle trajectories in a solid-rocket motor under several acceleration conditions have been simulated using a combined Eulerian-Lagrangian analysis. This analysis uses the numerical solution of ensemble-averaged Navier-Stokes equations for the continuous phase, coupled with a Lagrangiah analysis for the discrete (particulate) phase to simulate the two-phase internal flow. A Linearized Block Implicit scheme is used to solve the governing equations for the continuous phase, which allows the use of a highly stretched grid with sublayer resolution. The motion of the particles is tracked in computational coordinate space resulting in computational efficiency. The governing equations are written in generalized noninertial reference frame so that effect of motor acceleration can be easily included. While the analysis allows complete-coupled calculations, the present study has neglected the effect of the participate phase on the gas-phase flowfield. Particle trajectories under specified acceleration conditions, that include axial acceleration, axial and lateral acceleration, as well as a centrifuge test for a tandem pulse rocket motor have been calculated. The calculated results indicate that the acceleration effects strongly influence the particle impingement patterns on the motor case and the nozzle.