Numerical simulation of pitching airfoil performance enhancement using Co-Flow Jet Flow control

The two dimensional flow of an oscillating SC1095 airfoil with Co-Flow Jet (CFJ) flow control is simulated using Unsteady Reynolds Average Navier-Stokes (URANS). A 5th order WENO scheme for the inviscid flux, a 4th order central differencing model for the viscous terms and the one equation Spalart-Allmaras model for the turbulence are used to resolve the flow. The Mach number is 0.3 and Reynolds number is 3.93 × 10⁶ at reduced frequency from 0.05 to 0.2. The simulated results for the baseline agree reasonably well with the experiments for no-stall, mild-stall and deep-stall cases. The CFJ pitching airfoil is found to increase the airfoil performance for every flow studied. At C_μ = 0.08 the lift is increased by 32% and the drag is decrease by 80%. Considering only the aerodynamic forces applied on the airfoil and not the pumping power, (L/D)_ave for this case reach an outstanding 118.3. When C_μ is increased, the average drag becomes negative, proving the feasibility of a CFJ helicopter blade using its pump as the only source of power. Due to the removal of dynamic stall, CFJ airfoil is able to remove the sharp moment drop at high angle of attack.