Improved Delayed Detached Eddy Simulation of Co-Flow Jet Flow Control in Extreme Adverse Pressure Gradients

B. McBreen; Y. -C. Yang; G. -C. Zha; AIAA

This paper conducts an Improved Delayed Detached Eddy Simulation (IDDES) as a high fidelity verification of flows with extreme adverse pressure gradients (EAPG), which are enabled by Co-Flow Jet (CFJ) active flow control (AFC). We define an EAPG to be an adverse pressure gradient that is at least ten times larger than the maximum adverse pressure gradient sustainable by the non-controlled flow of a baseline case at the same conditions. This paper simulates the flow around a CFJ6421-SST150-SUC247-INJ152 airfoil at an angle of attack (AoA) of 65 degrees and a jet momentum coefficient (C-mu) of 2.5, which achieves a super-lift coefficient of C-L = 9.58. As a baseline for comparison, the NACA6421 airfoil is also simulated using IDDES at an AoA of 14 degrees, at its CLmax condition just before stall. The simulation is conducted using FASIP, an in-house CFD program. The spatially filtered Navier-Stokes equations are solved using a fifth-order WENO reconstruction scheme for the inviscid fluxes and a fourth order central differencing scheme for the viscous fluxes. The CFJ airfoil demonstrates a remarkable ability to maintain attached flow at alpha = 65 degrees, generating an EAPG around the leading edge of the airfoil and immediately downstream of the injection slot. The CFJ airfoil achieves maximum streamwise and centrifugal pressure gradient coefficients 737 and 68 times higher than those of the baseline airfoil, respectively. This paper reinforces our understanding of the the CFJ's interaction with EAPGs, investigating the physical mechanisms underlying EAPG formation, and the CFJ's capacity to sustain attached flow within such conditions. Furthermore, it further validates the findings of our prior 2D URANS study, which first introduces the EAPG. Given its ability to maintain attached flow in the presence of an EAPG, the CFJ airfoil has the potential to be a promising and highly effective flow control device.