Reduction of Drag by Corrugating Trailing Edges

摘要

A scheme to reduce the drag of a blade with a thick trailing edge by making the trailing edge corrugated was tested. A blade was made with a trailing edge having a sine wave shape, wavelength 8 inches, amplitude 1 inch, and thickness 1.5 inches smoothly becoming flat over one third of the chord length. A flat blade of the same leading dimensions, 20 x 20 x 1.5 inches, was made as a control. Both blades were tested under the same conditions in a low speed wind tunnel. Drag coefficients were obtained by both a wake traverse and by measuring base pressures. The former method showed that the corrugated blade caused a reduction in total drag coefficient of 25% and the latter a reduction in base drag of 35%. Thus the corrugated trailing edge causes a significant improvement. This may have important applications in increasing the efficiency of turbine blades which need to have thick trailing edges because of their necessity to be cooled.