A higher fidelity approach for incorporating tip shroud geometry into aerodynamic flutter computations of rotating turbomachinery

Authors

Alexander V Rozendaal - Power Systems Mfg., LLC, Ansaldo Energia Group
Alex Torkaman - Power Systems Mfg., LLC, Ansaldo Energia Group
Gregory Vogel - Power Systems Mfg., LLC, Ansaldo Energia Group
Alfio Lo Balbo - Ansaldo Energia

Abstract

Computational Fluid Dynamics (CFD) solvers can be used for predicting aerodynamic stability of rotating turbomachinery. Frequency-domain methods offer increased computational efficiency for flutter applications. They enable the unsteady aerodynamic response for an entire un-shrouded blade row to be computed using only a single sector numerical passage. The relative motion of the blade is simulated through a mesh-morphing procedure according to the blade’s structural mode shape. However surface conformity along the periodic planes of the passage is required. Such a requirement is especially difficult to satisfy for blades with interlocked tip shrouds that suppresses the periodicity during the morphing cycle. For this reason, such flutter simulations are often performed without a blade tip shroud. This paper examines the effects of the neglected tip shroud assumption on the aerodynamic flutter characteristics of a shrouded turbine blade by implementing a method in which to incorporate the interlocked tip shroud into the CFD simulation.