Session: 28-01: Reduced-Order Modeling of bladed disks

Paper Number: 151764

Capturing Mistuning Within Shrouded Integrally Bladed Disks With the Generalized Model of Mistuning 

Bladed disks are designed to be cyclic structures that ideally have identical sectors. There will, however, always contain mistuning, which is blade to blade differences that break the cyclic symmetry of the system and can cause an increase in vibrational amplitudes. The most common way mistuning is modeled is using small frequency deviations in each of the blades. Many different methods for producing reduced order models (ROMs) have been developed with each generally designed to accurately capture a one form of mistuning that is present in the system. For high dimensional finite element models, ROMs are vital to perform many structural dynamic calculations quickly. These ROMs are also vital to perform any statistical analysis which must be performed when analyzing random mistuning. Recently, a Generalized Model of Mistuning (GMM) method was developed that enables efficient construction of ROMs that can readily capture multiple forms of mistuning. GMM has been demonstrated to be an effective way to model mistuning separately in the blade and disk where the mistuning can be a combination of damping, small or large stiffness or geometric mistuning.

This work aims to extend GMM to capture systems that contain shrouds, dual flow path blisks, and bladed disks with interface mistuning. GMM uses an augmented Craig-Bampton component mode synthesis (CB-CMS) that allows for the decoupling of the sector level model to enable mistuning implementation into different components of each sector. The reduction of individual components is done in GMM by solving for normal modes and constraint modes, similar to the original CB-CMS. The combination of the various components occurs through the projection of the motion from the interface from special blade-disk interface modes. GMM performs a special modal reduction of the interface along with the internal DOFs of the disk sector to greatly reduce the size of the model and the calculations in constructing it. GMM uses only single sector models and calculations in the construction of the ROM, allowing realistic industrial models to be analyzed. This can be extended to capture dual flow path systems and allows for the implementation of different mistuning patterns to the dual flow path blades. For each of the systems studied GMM is validated using a full stage finite element model.

Presenting Author: Troy Krizak The Ohio State University

Presenting Author Biography: Troy is currently a PhD candidate at The Ohio State University working in the Gas Turbine Laboratory and the Nonlinear Dynamics and Vibration Laboratory. Troy works under his graduate advisor, Kiran D'Souza.

Authors:

Troy Krizak The Ohio State University
Kiran D'souza The Ohio State University