Analysis on the Reduction of Rotor Blade Vibration Using Asymmetric Vane Spacing

Abstract

Asymmetric vane spacing design has drawn the attention of many researchers as a targeted and potential method of controlling the blade forced response. In this paper, we studied the influence of asymmetric stator vane spacing variation on the reduction of downstream rotor blade vibration. We use a simplified method to calculate the aerodynamic force on the rotor blade surface. To validate the accuracy of the simplified method and to calculate rotor blade vibration response under asymmetric aerodynamic load, a transient analytical fluid-structure interaction method was applied. In this paper, we adopt two high pressure turbine stages as the research objects. We compared the stress fluctuation characteristics of the rotor blades in the two stages to study the similarity and difference under asymmetric vane spacing. The results indicated that asymmetric vane design does not affect the aerodynamic performance of the turbine stage very much. The level of excitation force at specific frequencies on the rotor blade surface can be reduced by applying a proper distribution of asymmetric vanes, which led to a significant impact on the reduction of the amplitude of vibration stress of the rotor blade. By the comparison of two turbine stages, we certified that the influence of vane spacing changes on average stress of the rotor blade is determined by the relationship between aerodynamic force direction and the rotor blade deformation direction. Fatigue life of STAGE B rotor blade could be increased by a maximum of 20.3% in case B2. The result shows that it is possible to reduce vibration and increase rotor blade fatigue life by asymmetric vane designs by applying a judicious choice of asymmetric parameter.