A Computational Procedure to Improve Airfoil Performance Considering Shape and Flow Interactions

摘要

Despite remarkable progress in shape design issue, there is still room to work on this topic considering different flow field conditions and specific aerodynamic applications.Today,the optimization techniques are known as a major tool to reach the best possible aero- dynamic shape for some specified conditions.In general direct optimization techniques,the optimization process is started from choosing a suitable primitive shape and the shape is improved by suitable considerations of the design objectives and constraints.In a similar attempt,we develop a new optimization strategy to improve the airfoil shape for specific applications. The strategy involves several stages.It includes to determine the flow conditions and design parameters, to establish the objective function,to select a suitable primitive shape,to generate a mechanism for inserting gradual shape changes,to generate grids around each defined shape,to solve the flow field for each separate shape,to collect the solution data,to change the discrete data to the continuous distribution functions, to construct the objective function,and to minimize the objective function using the steepest descent approach.No constraint function is incorporated into the constructed objective function.The cruise flight of an aircraft at an specified altitude is supposed to be the flow field conditions around the proposed airfoil.Nevertheless,the flow field is assumed to be viscous and compressible as well as turbulent.The procedure is tested starting from two generic airfoil shapes with and without camber.The developed algorithm works well for both cases;however,it may not converge to identi- cal shapes if the primitive shapes are not identical.