Abstract:

This paper presents a numerical study of series of NPU transonic airfoils.The reliability of the numerical analysis" is verified by the experimental results of two of such airfoils.The investigation shows that the design points of these airfoils are all within the boundary of drag divergence with certain marginsdue to the advantage of small wave drag of the airfoils.But the pressure distributions show some waviness on the suction peaks,and there are shock waves in the front part of some airfoils,as well as a strong pressure gradient near the trailing edge. These lead to early transitions and-early separation of the boundary layer flows.A modified design has been carried out mainly by specifying new curvature distributions of the airfoil contours and solving the curvature equations.The detailed computations on boundary layer flows also indicate a good improvement. The new airfoil has a long extension of laminar flow, and the turbulent separation has been shifted to the trailing edge. The efficiency of the curvature modification method is thus demonstrated.

Key words: airfoils, optimization, aerodynamic characteristics