Aerodynamic and Acoustic Optimization for Fan Flow Deflection

This investigation seeks to optimize the implementation of fan flow deflection for jet noise suppression from a supersonic turbofan nozzle with bypass ratio 2.7. The design objective is to maximize reduction of noise perceived by the community while minimizing aerodynamic losses. An adjoint method for shape optimization is used to obtain deflector vane designs with sufficient flow deflection and minimum thrust penalty. A NACA0012 airfoil is used as the initial shape for the vane airfoil. Optimization leads to reduction in specific-thrust loss and a thicker airfoil which is beneficial for structural reasons. The optimal vane airfoil is used in a parametric acoustic study of 50 deflector configurations with variable vane chord length, angle of attack and azimuth angle. The best configuration leads to reductions in effective perceived noise level (EPNL) of 2.8 dB in the downward direction and 2.5 dB in the sideline direction. Addition of a porous wedge-shaped fan flow deflector increases the EPNL reductions to 5.0 dB and 3.9 dB in the downward and sideline directions, respectively.