Design of a Constant Stress Steam Turbine Rotor Blade

Abstract

This paper presents a design procedure for a constant stress low pressure steam turbine blade. Such blades suffer from different types of loadings leading to different types of stresses, like tensile and bending stresses due to centrifugal force and steam flow loading. The centrifugal force is one of the problems that face the designers of blades especially the long ones. One way to tackle this is by using twisted blades and/or using variable cross-section area blades. Six types of blades were studied in this paper. One for constant cross sectional area blade as a reference. The other five are for reducing cross sectional area blades of varying curvature. Reducing the cross sectional area reduces the mass of blade and hence reduces the centrifugal stresses. The performance of the cases was then checked and found to be within satisfactory ranges. The results obtained are then utilized in the design of the constant stress blade. Which was checked with references for three locations (stages) and was found satisfactory?