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Computational fluid dynamic simulations (CFD) were used to predict the aerodynamic coefficients and flow field over a spinstabilized, 25-mm, sub-caliber training projectile. The primary objective of the investigation was to determine the CFD parameters necessary for the accurate prediction of the Magnus moment and roll damping of a spin-stabilized projectile. Archival experimental data was used to validate the numerical calculations. The Mach number range investigated was from 0.4 to 4.5. Steady state CFD calculations predicted the drag, normal force, pitching moment, and normal force center of pressure very well to within 10% of the experimental data. Time-accurate, detached-eddy simulations were found necessary to predict the Magnus moment in the subsonic and transonic flow regimes. Steady state CFD was found adequate to calculate the roll damping, which was predicted to within 15% of the experimental data in both steady state and time accurate calculations.
Computational fluid dynamic simulations (CFD) were used to predict the aerodynamic coefficients and flow field over a spinstabilized, 25-mm, sub-caliber training projectile. The primary objective of the investigation was to determine the CFD parameters necessary for the accurate prediction of the Magnus moment and roll damping of a spin-stabilized projectile. Archival experimental data was used to validate the numerical calculations. The Mach number range investigated was from 0.4 to 4.5. Steady state CFD calculations predicted the drag, normal force, pitching moment, and normal force center of pressure very well to within 10% of the experimental data. Time-accurate, detached-eddy simulations were found necessary to predict the Magnus moment in the subsonic and transonic flow regimes. Steady state CFD was found adequate to calculate the roll damping, which was predicted to within 15% of the experimental data in both steady state and time accurate calculations.
The prediction of the dynamic stability derivatives-roll-damping, Magnus, and pitch-damping moments-were evaluated for three spin-stabilized projectiles using steady-state computational fluid dynamic (CFD) calculations. Roll-damping CFD predictions were found to be very good across the Mach number range investigated. Magnus moment predictions were very good in the supersonic flight regime; however, the accuracy varied in the subsonic and transonic flight regime. The best Magnus moment prediction in the subsonic flight regime was for the square-base projectile that did not exhibit highly nonlinear Magnus moments. A primary contribution of this report is the demonstration that the pitch-damping moment can be adequately predicted via steady-state methods rather than resorting to unsteady techniques. The predicted pitch-damping moment compared very well to experimental data for the three projectiles investigated. For one configuration, the pitch-damping moment was predicted by several CFD codes, two different steady-state methods, and a time-accurate planar pitching motion method. All methods compared very well to each other and to the experimental data.
Containing the proceedings of the Third International Conference on Computational Ballistics, this book presents new ideas and advanced developments in the field of study of Computational Ballistics. Ballistic studies include applications as varied as the study of the structural and control behavior of rockets and communication satellites; bird strike effects on commercial aircraft, terrorist attacks and automobile crack worthiness modelling. Many basic problems of ballistics are similar to those in other fields of applications, such as combustion, heat conduction, in-flight structural behaviour, trajectory related issues, contact, impact, penetration, structural response to shock waves and many others.A valuable contribution to its field, this text will be of interest to researchers involved in the different areas of computational ballistics and their relationship between computational methods and experiments. Notable topics include: Systems and Technolog; Combustion and Heat Transfer; Propellants; Fluid Dynamics; Fluid Flow and Aerodynamics; In-Flight Structural Behaviour and Material Response; Guidance and Control; Perforation and Penetration Mechanics; Fluid-structure Interaction; Experimental Mechanics/ballistic and Field Testing; High Rate Loads; Composite Material; Shock and Impact.
The Computational Aerodynamics Branch, Launch and Flight Division has been actively developing the capability to predict the aerodynamics of US Army projectiles using Computational Fluid Dynamics (CFD) techniques. Currently under development is the capability to predict the supersonic aerodynamics of finned projectiles such as kinetic energy (KE) penetrators. In the current research effort, several important aerodynamic parameters which influence the roll characteristics of a fielded kinetic energy projectile (M735) have been predicted using CFD techniques. These parameters include the roll producing moment (at zero spin rate), the roll damping moment, and the equilibrium spin rate, defined as the spin rate for which the net roll moment is zero. Viscous CFD computations have been performed over a range of Mach numbers and spin rates using the US Army's Cray-2 supercomputer located at the Ballistic Research Laboratory. The computed results have been used to benchmark and validate engineering approaches for computing these aerodynamics coefficients.
Providing new chapters, homework problems, case studies, figures, and examples, Ballistics: Theory and Design of Guns and Ammunition, Second Edition encourages superior design and innovative applications in the field of ballistics. It examines the analytical and computational tools used to predict a weapon’s behavior in terms of pressure, stress, and velocity, demonstrating their applications in ammunition and weapons design. What’s New in the Second Edition: Includes computer examples in Mathcad (available on the CRC website) Adds a section of color plates, to better help readers visualize the physical concepts of ballistics Contains sections on modern explosives equations of state for detonation physics modeling and on probability of hit Provides a solutions manual for those teaching college and training courses This book covers exterior ballistics, exploring the physics behind trajectories, including linear and nonlinear aeroballistics, and focuses on the effects of projective impact, including details on shock physics, shaped charges, penetration, fragmentation, and wound ballistics. Reviews and integrates the fundamental science and engineering concepts involved in guns and ammunition Uses straightforward, easy-to-read style, and careful development of complex topics Shares insights rooted in the experience of renowned experts, many associated with the National Defense Industrial Association (NDIA) and International Ballistics Society The field of ballistics comprises three main areas of specialization: interior, exterior, and terminal ballistics. This book explains all three areas, offering a seamless presentation of the complex phenomena that occur during the launch, flight, and impact of a projectile.
Includes papers that were first presented at a September 2011 conference organized by the National Defense Industrial Association and the International Ballistics Society. This title includes a CD-ROM that displays figures and illustrations in articles in full color along with a title screen and main menu screen.