Computational aerodynamic investigation of long strake-tail missile configurations

Abstract

The efforts for the computational investigation and validation of different Missile Configurations tested at the U.S. Air Force Academy are summarized. The missile configurations considered have a streamlined body fitted with upstream strakes and cruciform all-movable tail fin surfaces and include: 1) a baseline with no fin deflection 2) a Roll10 configuration in which all fin surfaces are deflected 10 degrees to produce a positive roll moment 3) a Roll20 configuration 4) a Pitch20 configuration in which side fin surfaces are only deflected to produce a positive pitch moment 5) and finally a Pitch/Yaw10 configuration. Computational grids were generated around these geometries and grid details are provided. The simulations are performed for angles of attack in range of [0∘-15∘] and Mach numbers of 1.17, 2.49 and 4.39, at Reynolds numbers per length of 6.029 × 105, 6.818 × 105, and 8.89 × 105 per inches, respectively. Two different Computational setups were investigated: a) a steady-state b) and an unsteady. The convergence plots are given. The force and moment coefficients were extracted from simulation data and compared with each other for these missile configurations. Finally, the observed flow features are detailed including shock/expansion waves and separated and vortical flows. It should be noted that experimentation of missile test cases at the small test section of the USAFA Trisonic wind tunnel at supersonic speeds is complex and is subjected to model integrity under high loads, short test duration, mounted sting, wall effects, and other concerns. CFD predictions of these missiles bring confidence in measured aerodynamic data and complement wind tunnel experiments especially at conditions with large uncertainty in the wind tunnel. CFD predicted force and moment coefficients were compared against wind tunnel data. A good agreement was found at most conditions between two approaches.