Airfoil Optimization Design of Tiltrotor Aircraft Based on the Computational Fluid Dynamics Method

摘要

The aim of this work is to provide a systematic study on tiltrotor airfoilaerodynamic design based on high-fidelity computational fluid dynamics(CFD) analyses. It mainly involves two optimization problems. The first partis carried out to find an airfoil geometry which provides the maximum valueof lift-to-drag ratio in high-speed airplane mode. The initial shape is a NACA64A221 airfoil which is parameterized by Hicks-Henne functions. A novelmesh deformation algorithm based on inverse distance weighting (IDW)interpolation and transfinite interpolation (TFI) is presented for meshgeneration. Numerical simulations are performed with the ReynoldsaveragedNavier-Stokes equations supplemented with the Spalart-Allmarasturbulence model. By using NLPQL optimization algorithm, the lift-to-dragratio of the optimal airfoil has been improved by 46.57% compared to theinitial airfoil. On the basis of the optimized shape, the second part of thispaper is conducted to design the trailing edge flap and find out the optimalflap deflection angle for minimum download force in helicopter mode. It isdemonstrated that the optimal flap deflection angle is 65° and the downloadcan be reduced by 44.47% regarding the undeflected flap case.