Numerical investigation of coflow jet active flow control 3d swept cylinders

This paper studies aerodynamic force enhancement and flight control using Co-Flow Jet (CFJ) active flow control for 3D swept cylinders. The application background is to replace the V-tail control surface for aerial refueling boom. Past studies show the ability for CFJ actuated cylinders to outperform potential flow predictions of maximum lift. This study applies similar methodology to higher Mach flows and 3D swept cylinders in order to control the motion of the cylinder. The CFD simulations employ a validated RANS solver with one-equation Spalart-Allmaras turbulence modeling. The inviscid fluxes are discretized with a 3rd order WENO scheme, and the viscous terms are discretized with 2nd order central differencing. With Mach numbers of 0.25 for a 2D cylinder, a lift coefficient of 10.6 is achieved with substantially lower power consumption than the previous study. The 2D CFJ cylinder configuration is then used to create the 3D swept cylinder. Similarly, a 3D cylinder swept at 60 degrees with an aspect ratio of 10, the study purpose is two fold: 1) side force enhancement by CFJ for lateral motion control; 2) Side force cancellation by CFJ to enhance the pitching moment for longitudinal control. By applying a set of CFJ flow control for 15% of the cylinder span, a very large side force coefficient of 3 is achieved. It is more than required to control the cylinder lateral motion. By using two sets of CFJ oriented in opposing injecting directions, the side force can be canceled out, while enhancing the pitching moment for longitudinal control. The CFJ injection and suction slot location affect the direction of the resultant force vector. CFJ active flow control can be manipulated to vector the aerodynamic force on the CFJ cylinder. This study indicates that it is feasible to control a 3D swept cylinder lateral and longitudinal motion using CFJ without a V-tail control surface. However, the study is just a initial step. More detailed CFJ and configurations design iteration are necessary with wind tunnel testing to validate the flight control features.