Unsteady Flow Computations of a Finned Body in Supersonic Flight

Abstract

*This paper describes a multidisciplinary computational study undertaken to compute the flight trajectories and simultaneously predict the unsteady free flight aerodynamics of a finned projectile at supersonic speeds using an advanced unstructured time-accurate NavierStokes computational technique. Actual flight trajectories are computed using an advanced coupled computational fluid dynamics (CFD)/rigid body dynamics (RBD) technique. In addition, our goal is to be able to extract the aerodynamic coefficients from these fully coupled time-accurate CFD/RBD computations. Computed positions and orientations of the projectile have been compared with actual data measured from free flight tests and are found to be generally in good agreement. Unsteady numerical results obtained from the coupled method and unstructured grids show the flow field, the extracted aerodynamic forces and moments, and the flight trajectories of the projectile. Aerodynamic coefficients such as the dynamic derivatives have been obtained using a separate unsteady time-accurate CFD approach and have been compared with the extracted aerodynamic coefficients from the fully coupled dynamic simulations. I. Introduction he prediction of aerodynamics for projectile configurations is essential in assessing the performance of new designs. Understanding the aerodynamics of projectiles, rockets, and missiles is critical to the design of stable configurations and contributes significantly to the overall performance of weapon systems. 1-3 The prediction of aerodynamic coefficients for these weapon systems is essential in assessing the performance of new designs. Numerical simulations have the potential of greatly reducing design costs while providing a detailed understanding of the complex aerodynamics associated with each change. Recently, we have made progress in coupling computational fluid dynamics and flight dynamics to perform required multidisciplinary simulations for moving body problems. This involves real-time multidisciplinary-coupled computational fluid dynamics/rigid body aerodynamics computations for the entire flight trajectory of a complex guided projectile system. It can lead to accurate determination of aerodynamics, critical to the low-cost development of new advanced guided projectiles, rockets, missiles, and smart munitions. Improved computer technology and state-of-the-art numerical procedures now enable solutions to complex, 3-D problems associated with projectile and missile aerodynamics. In particular our recent focus has been directed at the development and application of advanced predictive capabilities to compute unsteady projectile aerodynamics, especially during and after control maneuvers. During these maneuvers