Torsional Strain of Long Steam Turbine Blades

Abstract

Long naturally twisted blades of steam turbines during the operation experience the aggregate stress-strain state. The strain of the elastic bootstrapping, which is a function of the geometry of the blade and the impact of centrifugal forces developed by it, in turn, causes the shear stresses, the distribution of which along the blade height has not been reflected in the press.The article presents the results of the study of the effect of smoothness of the derivative of natural blade twist angles in the initial state on the nature of the distribution of shear stresses caused by the elastic bootstrapping in sections of the blade.The influence of different kinds of errors (design, production) on the growth of additional shear stresses was determined. The effect of abrupt changes of the derivative of the angle of the natural twist on the nature of the elastic bootstrapping of the blade was revealed.The article provides recommendations to reduce the additional shear stresses caused by a violation of the smoothness of natural twist angles, as well as to compensate for deviations from the design values of the natural twist angles in the process