A Parametric Method of Turbine Blade Profile Design

The profile shape of an axial turbine blade is required to satisfy both aerodynamic and mechanical criteria; the designer wants the most favorable velocity distribution achievable with the permissible blade thickness. The design involves some trial-and-error, especially if the profile is initially prescribed by solely aerodynamic or solely mechanical requirements. A new design technique is described in which both aerodynamic and mechanical requirements are prescribed. The shape is defined by an algebraic function of eight parameters: blade inlet and outlet angle, maximum thickness, trailing edge thickness and wedge angle, leading edge radius, and the points of maximum thickness and maximum camber. Some of these are chosen to satisfy mechanical requirements, and curves are given recommending the best values of the remaining parameters from aerodynamic considerations, with the exception of the position of maximum camber. By varying that over a narrow range, a good shape can quickly be selected. A computer program for designing blades this way and analyzing blades designed in other ways is described.Copyright © 1974 by ASME