Consideration of Interface Damping in Shrouded Mistuned Turbine Blades

摘要

Running turbines are exposed to high mechanical load. Due to gas excitations the structure can vibrate with high oscillation amplitudes which can damage the turbine blades. Mistuning can additionally lead to high local stresses which must be taken into account in the turbine design process. Introducing damping due to friction in the interface of shrouded turbines can be used to decrease this oscillation amplitudes. The computation of full turbine finite-element models with nonlinear coupling forces causes high computational costs. As a consequence, Component Mode Synthesis methods are used to reduce the number of DOFs of each blade substructure. Mistuning of the blades can now be applied in modal space. Coupling of the mistuned substructures is done by nonlinear interface forces which have to be included in the substructuring formulation. The resulting reduced and mistuned system with nonlinear coupling forces is solved with a Harmonic Balance Method such that the effect of mistuning and interface damping can be studied very efficiently.