Lateral Control Jet Aerodynamic Predictions for a 2.75-in Rocket Testbed Munition

Report No. ARL-TR-3165
Authors: Paul Weinacht
Date/Pages: April 2004; 40 pages
Abstract: The aerodynamic performance of lateral control jets for a 2.75-in rocket testbed munition has been investigated using a sophisticated numerical technique. The computational approach utilized a finite difference-based overset gridding approach to predict the interaction of the lateral control jet with the external flow around the munition and the resulting effect on the lateral control jet performance. The jet interaction effect was found to be an important contributor to the overall effectiveness of the lateral control jet. The circumferential location of the jet relative to the tail fins was also found to influence the jet?s effectiveness. A variation of 30% in the net jet moment was computed for the two fin orientations considered in the study. The predictions also showed that spin did not significantly influence the lateral control jet performance for the expected spin rates of the testbed munition; however, if the spin was increased significantly, the resulting jet interaction produced a misalignment of the total jet thrust relative to the nozzle. Single and tandem jet configurations were examined. For the configurations examined here, the tandem jet doubled the effective jet thrust, although a similar effective jet thrust could be obtained by sequential independent firings of both jets. Time-dependent predictions of the performance of pulsed lateral control jets indicate that steady-state flow is attained during the duration of the firing cycle, and the overall performance of the pulsed jets can be represented reasonably well by the steady-state jet-on performance.
Distribution: Approved for public release
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Last Update / Reviewed: April 1, 2004