Calculation of the turbulence characteristics of flow around a circulation control airfoil using les (invited paper)

Journal article

Large-eddy simulations of high-Reynolds-number flow around a non-cambered, ellipticleading- edge circulation control airfoil (using a Coanda wall jet blowing over a rounded trailing edge) are performed to investigate detailed turbulence characteristics of the flow. The freestream Reynolds number based on the airfoil chord is 0.49 million, the radius of the rounded trailing edge is 9.46% chord, and the jet-slot height is 2.43% trailing-edge radius. The main focus of the study is on the turbulent Coanda flow separating from the rounded trailing edge. A sufficiently large computational domain in the spanwise (periodic) direction is employed to capture natural development of turbulent coherent structures in the flow. Two different jet-blowing rates are simulated, which correspond to jet Reynolds numbers of about 4500 and 7200 based on the jet-slot height; the lower jet-blowing case agrees well with experiments. A number of backward-tilted hairpin vortices are found to be generated downstream of the jet exit and to develop until they finally disappear prior to the flow separation. These hairpins are located in the outer shear layer of the wall jet, create a strong upwash between their legs, and thus lift the high-momentum flow below the hairpins upward. Detailed turbulence statistics are also calculated.

Authors: Nishino, T; Hahn, S; Shariff, K

• Journal: 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition
• Publication date: 2010-01-01
• Language: English