Numerical Simulation of Two and Three Dimensional Circulation Control Problems

Abstract

The flows about 2-D and 3-D bluff trailing edge circulation control (CC) airfoils are computed using steady Reynolds Averaged Navier-Stokes (RANS) methods. The 2-D foil is the NCCR 1510-7067 elliptical CC airfoil with circular and logarithmic spiral trailing edge geometries. The free stream Reynolds number, based on chord, is 5.45 × 10 5 , with a free stream Mach number of 0.12. For the circular trailing edge the slot height, blowing rate and angle of attack are varied, while for the logarithmic spiral only the blowing rate is varied. The 3-D foil is a semi-span wing with an elliptical cross section. It is run with a chord-based Reynolds number of 2 × 10 6 and two blowing rates. The 2-D flows are computed using the compressible, segregated solver, Fluent. 2-D results show that the full-Reynolds stress turbulence model (FRSM) predicts the correct jet detachment behavior for the circular trailing edge although the integrated lift forces are consistently underpredicted. The coanda jet detachment point for the logarithmic spiral trailing edge is predicted correctly for a lower blowing rate, but as blowing rate increases, the jet does not detach until it has wrapped around to the pressure side. We show additional 2-D results using mesh refinement via grid adaption and isotropic eddy viscosity turbulence models. The 3-D simulations use the incompressible segregated Fluent solver applying the k −ω SST turbulence model. Results show a slight attachment of the the coanda jet on the pressure side, but the results are generally encouraging.