Even though Finite Element Analysis (FEA) is considered to be an accurate static and dynamic simulation method, it is used only to verify the Mechanical Integrity (MI) of Steam Turbine (ST) blades, due to the time required to set up and perform a typical FEA. Furthermore, the complexity of the blade model results in convergence issues that further increase the analysis time, which can last several days. Instead, faster, lower order empirical tools with increased conservatism are preferred for the design phase.
Based on parametric steam turbine blades definition, the Mechanical Integrity and Design Analysis Suite (MIDAS) provides a platform for rapid, fully-automated 3D model generation and FEA. The analysis applies simplified contact interactions on a fully structured mesh, aiming primarily for model convergence in a short time, whilst maintaining the required accuracy. In order to verify that, an extended comparison of MIDAS static and vibrational analysis results with the state-of-the-art FEA and experimental measurements is performed.
Therefore, with MIDAS an accurate full FEA is completed within few minutes for each blade, speeding up the MI validation process and enabling its use at the design of every ST blade. Furthermore, the use of FEA contributes to an extended blade application envelope and optimised blade geometry. As a result, MIDAS presents several benefits to new and existing ST customers including increased operational flexibility, extended blade life, faster delivery of the ST cylinders at a lower acquisition cost and extended outage intervals.
Finite element modelling of residual stresses in shot-peened steam turbine blades