Hot Blade Shape Reconstruction Considering Variable Stiffness and Unbalanced Load in a Steam Turbine

Abstract

The blades in the low-pressure stage of a steam turbine must be reverse engineered according to the ideal blade shape due to the deformation of the blade during operation. A numerical analysis model of the flow field of the blades is proposed, and the model is solved by alternating between the fluid domain and the solid domain. Considering the imbalance of the load acting on the blade surface and the change in the blade stiffness matrix when the steam turbine is running, the Newton–Raphson method is used to calculate the pressure of the steam fluid on the blade surface and the change in the flow field caused by the blade deformation in each time step. The data are exchanged between the fluid domain and the solid domain after a single-step solution is completed. The simultaneous changes in the fluid domain and the solid domain are discretized in very short time steps, and the process of the blade deformation from stationary to running is simulated by accumulating the time steps. Finally, the trends in the change in the blade deformation and the aerodynamic load during the deformation process are analyzed according to the result of the reconstruction of the blade shape.