A COMPARATIVE STUDY OF TWO TURBULENCE MODELS FOR MAGNUS EFFECT IN SPINNING PROJECTILE

Magnus force and moment must be predicted precisely during calculating trajectories and designing rotating projectiles.Domestic studies have focused on adult spin projectile, and foreign studies have not compared turbulence model utility in spinning wind-body combination either.This paper simulated the flow field around a spinning wind-body combination by solving unsteady compressible three dimensional Navier-Stokes equations with dual time step method.At the same time the discrepancy between Splalrt-Allmaras (SA) and k-!shear stress transport (SST) turbulence models are studied.For both turbulence models, dynamic coefficients have a good agreement with the Arnold Engineering Development Center (AEDC) experimental data and Army Research Laboratory (ARL) computational data.Flow field parameters such as velocity gradient, pressure magnitude, show significant change in the latter half profile due to spin.Distortion of boundary layer in middle and rear part is conspicuous.Asymmetric distortion of circumferential surface pressure and shear stress is the fundamental reasons for the Magnus effect.Flow field parameters on the left side of body show larger variance between SA and SST turbulence models than the right side, indicating that speed pulse and pressure fluctuation are stronger on the left.The turbulent viscosity coefficient near the wall computed by SA is larger than SST.According to the slice of y=0 m, surface pressure shows SA is smaller than SST, reaching a maximum difference of 6%, and shear stress of SA is larger than SST, up to a maximum difference of 35%.The inhibition strength for flow separation indicates that SA is stronger than SST.