Fluidic control of a 155 mm spin-stabilized projectile using Coanda effect

摘要

The present paper aims at investigating numerically the control of a 155 mm spin-stabilized projectile using Coanda effect. Flight Mach number ranges from M_∞, = 0.7 to M_∞ = 2.0. A tangentially-blowing jet exits over a convex surface at the base of the projectile and creates flow asymmetry which generates significant aerodynamic efforts. First, RANS simulations are performed without projectile rotation. The jet extends 18° azimuthally and numerous continuous blowing conditions are assessed. The variation of the normal force coefficient with respect to the momentum coefficient is presented for different free stream Mach number. The efficiency loss of the Coanda effect with supersonic jets and the deleterious effect of low blowing values are also discussed. Comparisons between over expanded, adapted and under expanded supersonic jets are finally presented. In the second part, URANS simulations accounting for a 400 Hz rotation are performed. Both continuous and periodic blowing are assessed. A pulsed jet is used in phase with the rotation to always act in a 90° sector centered in the lift plane. Resulting normal force benefits are more important than the static ones and spin-averaged values lead to a non-zero normal force increment. Then, four pulsed jets equally distributed along the circumference of the projectile are simulated to further improve the control authority. The jet separation process is also investigated to determine the azimuthal influence of the jet on the pressure distribution.