Modal Analyses of an Axial Turbine Blisk With Intentional Mistuning

Abstract

The potential of intentional mistuning to reduce the maximum forced response is analyzed within the development of an axial turbine blisk for ship diesel engine turbocharger applications. The basic idea of the approach is to provide an increased aerodynamic damping level for particular engine order excitations and mode shapes without any significant distortions of the aerodynamic performance. The mistuning pattern intended to yield a mitigation of the forced response is derived from an optimization study applying genetic algorithms. Two blisk prototypes have been manufactured a first one with and another one without employing intentional mistuning. Hence, the differences regarding the real mistuning and other modal properties can be experimentally determined and evaluated as well. In addition, the experimental data basis allows for updating structural models which are well suited to compute the forced response under operational conditions. In this way, the real benefit achieved with the application of intentional mistuning is demonstrated.

Vibration analysis of an axial turbine blisk with optimized intentional mistuning pattern

“…16), nearly all other TWM participating to the response are contributing additional damping. The resulting aerodynamic damping [18] can be computed by…”

Nonproportional Intentionally Mistuned Turbine Blisk Design with Improved Component Modal Synthesis

“…e intentionally mistuned design of blisks is performed in the recent years. For example, the intentional mistuning was introduced to reduce the forced response of blade [32][33][34][35]. In addition, some other scholars conducted the reliability and optimization of blades [36][37][38].…”

Generalized SAFE Diagram for Mistuned Bladed Disks

“…As a consequence, some blades may be more excited than others in a narrow frequency range near the non-mistuned (nominal geometry) theoretical value. Despite this, controlled mistuning can be intentionally introduced and optimized in order to reduce the overall vibrational magnitude [7][8][9]. The mistuning introduced is usually significantly larger than the additional random (or stochastic) mistuning [10].…”