Aerodynamic Performance of Fan-Flow Deflectors for Jet-Noise Reduction

This paper presents a computational study on the aerodynamic effectiveness of vane-type fan-flow deflectors used for reducing jet noise from a supersonic turbofan exhaust with bypass ratio of 2.7. The numerical code solved the three-dimensional Reynolds-averaged Navier–Stokes equations. A series of nozzle configurations using deflector vanes of variable number, airfoil section, azimuthal mounting, and angle of attack are investigated. The flowfield around the vanes, overall flow turning angle, reduction of turbulent kinetic energy, thrust loss, and blockage caused by the deflector vanes are examined and characterized. Vanes using symmetric or moderately cambered airfoils cause much smaller aerodynamic losses than vanes with highly cambered sections that induce shock phenomena. Significant reduction in the turbulent kinetic energy on the underside of the jet plume can be achieved with overall flowdeflection of about 1 deg and attendant specific thrust loss of 0.1%.This thrust loss is deemed small enough that a fixed-vane installation may be feasible for practical application.