1. Figures 4-7 demonstrate the calculated progression of the burning surface of the propellant grain within the star slot for the Figure 4. Grain surface Temperature
2. Contours and Velocity Vectors, Single Port Igniter: t = 23.2 msec single port igniter presently used on the Space Shuttle SRM. Figure 4 illustratesthe situation at the time of first ignition, predicted to be at about 23 msec after igniter start. Note that this predicted time, which is probably low, is a function of the particular heat transfer model chosen. However, the burning sequence predicted by `.J' the model should be qualitativelycorrect and useful for comparativepurposes. Included in Fig. 4 is an overlay from Fig. 2 showing the Mach contours from the igniter plume. Even though the shock region is somewhat smeared out by the calculation technique, it is evident that first ignition occurs in the vicinity of the shock, as might be expected. Figures 5-7 illustrate both the progression of burning within the slot and the associated flow field induced by the igniter plume and the burning grain. Figure 5. Grain Surface Temperature
3. Results are shown in Figs. 8-11 for the case of a canted multi-port igniter,with the plume centerline inclined at an angle of 22.5' with respect to the motor axis of symmetry. Since the Space Shuttle SRM headend star grain has eleven slots, the mass flow contained in a given plume is only one
4. Figure 12 summarizes the results shown in Figs. 4-11 and also includes results for the 45' multi-port igniter case. Somewhat surprisingly, the results for the 45' case are not significantly different than those for the 22.5' case, at least insofar as the star slot is concerned.