Analysis of Bending Stresses for Steam Turbine Blades due to Aerodynamic Forces

Abstract

The rotor blades in a steam or gas turbine are exposed to the influence of transverse aerodynamic forces causing them to bend. These forces have static and variable components that affect, by their rapid change, directly on the strength of the rotor blades, causing vibration, fatigue and even breakage of the blades. The constant bending stresses are an important indicator of durability, as the variable forces and the variable stresses in the blades are directly proportional to the static stresses. Therefore, it is necessary to study methods for determining blade bending stresses due to static aerodynamic forces. In this research, an evaluation of bending stresses for cross section of relatively long turbine blade has been carried out through a case study. It has been shown that the maximum bending stress occurs at the entrance edge of the blade and the bending stress distribution along the blade shows that the maximum stress occurs at some distance from blade root depending on blade shape and working parameters.