CFD Simulations of a Finned Projectile with Microflaps for Flow Control

This research describes a computational study undertaken to determine the effect of a flow control mechanism and its associated aerodynamics for a finned projectile. The flow control system consists of small microflaps located between the rear fins of the projectile. These small microflaps alter the flow field in the aft finned region of the projectile, create asymmetric pressure distributions, and thus produce aerodynamic control forces and moments. A number of different geometric parameters, microflap locations, and the number of microflaps were varied in an attempt to maximize the control authority generated by the flaps. Steady-state Navier-Stokes computations were performed to obtain the control aerodynamic forces and moments associated with the microflaps. These results were used to optimize the control authority at a supersonic speed, M=2.5. Computed results showed not only the microflaps to be effective at this speed, but also configurations with 6 and 8 microflaps were found to generate 25%–50% more control force than a baseline 4-flap configuration. These results led to a new optimized 8-flap configuration that was further investigated for a range of Mach numbers from M=0.8 to 5.0 and was found to be a viable configuration effective in providing control at all of these speeds

Using Loop-Level Parallelism to Parallelize Vectorizable Programs

Approved for public release; distribution is unlimited. One of the major challenges facing “high performance computing ” is the daunting task of producing programs that achieve acceptable levels of performance when nm on parallel architectures. Although many organizations have been actively working in this area for some time, many programs have yet to be parallelized. Furthermore, some programs that were parallelized were done so for obsolete systems. These programs may run poorly, if at all, on the current generation of parallel computers. Therefore, a straightforward approach to parallelizing vectorizable codes is needed without introducing any changes to the algorithm or the convergence properties of the codes. Using the combination of loop-level parallelism and RISC-based shared memory SMPs has proven to be a successful approach to solving this problem. ii Acknowledgments The authors would like to thank Marek Behr for permission to use his results in this report. They would also like to thank the entire CHSSI CFD-6 team for their assistance in this work as part of that team. They would like to thank their many colleagues that have graciously assisted them in all aspects of the preparation of this report. Additional acknowledgments to Tom Kendall, Denice Brown, and the Systems Staff for all of their help. They would also like to thank the employees of Business Plus, especially Deborah Funk and Maria Brady who assisted in the preparation and editing of this report. This work was made possible through a grant of computer time by the DOD HPCM Program. The time was spent at the ARL-MSRC, NAVO-MSRC, NRL-DC, TARDEC-DC, and SPAWAR-DC along with smaller amounts of time at other sites. Funding was provided as part of the CHSSI administered by th