Determining the Influence of Casing Vibrational Behaviour On Rotordynamics

2021 ◽  
Author(s):  
Mona Amer ◽  
Martin Paehr ◽  
Lars Panning-von Scheidt ◽  
Joerg R. Seume ◽  
Joachim Schmied
Keyword(s):  
Numerical Model ◽  
Model Updating ◽  
Axial Compressor ◽  
Numerical Data ◽  
Order Model ◽  
Simplified Models ◽  
Reduced Order ◽  
Ultimate Objective ◽  
Supporting Structures

Abstract Casings of machinery and support structures have an influence on the rotordynamic behaviour which is commonly considered by simplified models (e.g. one degree of freedom models). These are in many cases insufficient. Hence, more accurate modelling approaches are required which can be used in the design process or the rotordynamic calculation to achieve a better representation of the overall vibrational behaviour. To study the effects of casing and supporting structures on rotordynamics, the casing modal parameters of an axial compressor are determined by an experimental modal analysis. In parallel, a numerical model is established. As experimental data are rarely found in the literature, this work focuses on the parameter identification of the casing structure. The results are subsequently incorporated into a model updating strategy, in order to tune and improve the numerical model. Experimental and numerical data are compared to assess the quality of the data and the results gained. The ultimate objective is a reduced order model, which can be integrated in existing rotordynamic tools via an interface while keeping the calculation time low.

Interface Reduction in Craig–Bampton Component Mode Synthesis by Orthogonal Polynomial Series

2017 ◽  
Vol 140 (5) ◽  
Author(s):  
Luigi Carassale ◽  
Mirko Maurici
Keyword(s):  
Degrees Of Freedom ◽  
Axial Compressor ◽  
Component Mode Synthesis ◽  
Order Model ◽  
Reduced Order ◽  
Interface Reduction ◽  
Interface Displacement ◽  
Polynomial Series ◽  
Efficient Representation

The component mode synthesis (CMS) based on the Craig–Bampton (CB) method has two strong limitations that appear when the number of the interface degrees-of-freedom (DOFs) is large. First, the reduced-order model (ROM) obtained is overweighed by many unnecessary DOF. Second, the reduction step may become extremely time consuming. Several interface reduction (IR) techniques addressed successfully the former problem, while the latter remains open. In this paper, we tackle this latter problem through a simple IR technique based on an a-priory choice of the interface modes. An efficient representation of the interface displacement field is achieved adopting a set of orthogonal basis functions determined by the interface geometry. The proposed method is compared with other existing IR methods on a case study regarding a rotor blade of an axial compressor.

scholarly journals Mistuning Identification and Model Updating of an Industrial Blisk

2006 ◽  
Author(s):  
Denis Laxalde ◽  
Fabrice Thouverez ◽  
Jean-Jacques Sinou ◽  
Ste´phane Baumhauer ◽  
Jean-Pierre Lombard
Keyword(s):  
Measurement Errors ◽  
Model Updating ◽  
Measurement Procedure ◽  
Forced Response ◽  
Reduced Order Model ◽  
Order Model ◽  
Reduced Order ◽  
Modal Data ◽  
Complete Study ◽  
Modal Equation

The results of a complete study of mistuning identification on an industrial blisk are presented. The identification method used here is based on a model-updating technique of a reduced-order model where measured modal data are taken as input. This reduced-order model is build using component mode synthesis and mistuning is introduced as perturbations of the cantilevered-blade modes. The measured modal data are extracted from global measurements of the blisk’s forced response. As we use a one point excitation, this measurement procedure allows the acquisition of the all modes of a given family with a quite simple experimental setup. A selection of the best identified modal data is finally performed. During the mistuning identification procedure, these measured data are regularized using an eigenvector assignment technique which reduces the influence of eventual measurement errors. An inverse problem is defined based on the perturbed (mistuned) modal equation, with measured modes as input and mistuning parameters as unknown. Then, the reduced-order model is updated with the identified mistuning, we first perform a correlation on modal responses (using eigenfrequency deviation criteria and MACs). Finally, correlation results on forced responses are presented and discussed.

scholarly journals Updating of aerodynamic reduced order models generated using computational fluid dynamics

2017 ◽  
Vol 232 (9) ◽  
pp. 1739-1763
Author(s):  
LM Griffiths ◽  
AL Gaitonde ◽  
DP Jones ◽  
MI Friswell
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Model Updating ◽  
Limited Range ◽  
Reduced Order Model ◽  
Reduced Order Models ◽  
Viscous Effects ◽  
Order Model ◽  
Reduced Order

Reduced order models of computational fluid dynamics codes have been developed to decrease computational costs; however, each reduced order model has a limited range of validity based on the data used in its construction. Further, like the computational fluid dynamics from which it is derived, such models exhibit differences from experimental data due to uncertainty in boundary conditions and numerical accuracy. Model updating provides the opportunity to use small amounts of additional data to modify the behaviour of a reduced order model, which means that the range of validity of the reduced order model can be extended. Whilst here computational fluid dynamics data have been used for updating, the approach offers the possibility that experimental data can be used in future. In this work, the baseline reduced order models are constructed using the Eigensystem realisation algorithm and the steps used to update these models are given in detail. The methods developed are then applied to remove the effects of wind tunnel walls and to include viscous effects.

scholarly journals Mistuning Identification and Model Updating of an Industrial Blisk

2007 ◽  
Vol 2007 ◽  
pp. 1-10 ◽  
Author(s):  
D. Laxalde ◽  
F. Thouverez ◽  
J.-J. Sinou ◽  
J.-P. Lombard ◽  
S. Baumhauer
Keyword(s):  
Measurement Errors ◽  
Model Updating ◽  
Single Point ◽  
Measurement Procedure ◽  
Forced Response ◽  
Reduced Order Model ◽  
Order Model ◽  
Reduced Order ◽  
Modal Data ◽  
Modal Equation

The results of a complete study of mistuning identification on an industrial blisk are presented. The identification method used here is based on a model-updating technique of a reduced order. This reduced-order model is built using component mode synthesis, and mistuning is introduced as perturbations of the cantilevered-blade modes. The measured modal data are extracted from global measurements of the blisk's forced response. As we use a single point excitation, this measurement procedure allows the acquisition of all the modes of a given family with a quite simple experimental set-up. A selection of the best identified modal data is finally performed. During the mistuning identification procedure, these measured data are regularized using an eigenvector assignment technique which reduces the influence of eventual measurement errors. An inverse problem, based on the perturbed (mistuned) modal equation, is defined with measured modes as input and mistuning parameters as unknown. Then, the reduced-order model is updated with the identified mistuning, we first perform a correlation on modal responses (using eigenfrequency deviation criteria and MACs). Finally, correlation results on forced responses are presented and discussed.

Experimental Study of the Fundamental Mistuning Model for Probabilistic Analysis

2005 ◽  
Author(s):  
M. R. Rossi ◽  
D. M. Feiner ◽  
J. H. Griffin
Keyword(s):  
Experimental Study ◽  
Statistical Model ◽  
Forced Response ◽  
Reduced Order Model ◽  
Laboratory Measurements ◽  
Order Model ◽  
Reduced Order ◽  
Bladed Disk ◽  
Two Factors

FMM is a reduced order model for efficiently calculating the forced response of a mistuned bladed disk. FMM ID is a companion program that determines the mistuning in a particular rotor. Together, these methods provide a way to acquire data on the mistuning in a population of bladed disks and then simulate the forced response of the fleet. This process is tested experimentally, and the simulated results are compared with laboratory measurements of a “fleet” of test rotors. The method is shown to work quite well. It is found that accuracy of the results depends on two factors: the quality of the statistical model used to characterize mistuning, and the sensitivity of the system to errors in the statistical modeling.

Fluid-Structure Interaction Using a Modal Approach

2011 ◽  
Author(s):  
F. Debrabandere ◽  
B. Tartinville ◽  
Ch. Hirsch ◽  
G. Coussement
Keyword(s):  
Fluid Structure Interaction ◽  
Axial Compressor ◽  
Linear Structure ◽  
Mode Shapes ◽  
Order Model ◽  
Modal Approach ◽  
Fluid Structure ◽  
Flow Solver ◽  
Reduced Order ◽  
Structure Interaction

A new method for Fluid-Structure Interaction (FSI) predictions is here introduced, based on a Reduced-Order Model (ROM) for the structure, described by its mode shapes and natural frequencies. A linear structure is assumed as well as Rayleigh damping. A two-way coupling between the fluid and the structure is ensured by a loosely-coupling staggered approach: the aerodynamic loads computed by the flow solver are used to determine the deformations from the modal equations, which are sent back to the flow solver. The method is firstly applied to a clamped beam oscillating under the effect of von Karman vortices. The results are compared to a full-order model. Then a flutter application is considered on the AGARD wing 445.6. Finally, the modal approach is applied to the aeroelastic behavior of an axial compressor stage. The influence of passing rotor blade wakes on the downstream stator blades is investigated.

Fluid–Structure Interaction Using a Modal Approach

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
F. Debrabandere ◽  
B. Tartinville ◽  
Ch. Hirsch ◽  
G. Coussement
Keyword(s):  
Fluid Structure Interaction ◽  
Axial Compressor ◽  
Linear Structure ◽  
Mode Shapes ◽  
Order Model ◽  
Modal Approach ◽  
Fluid Structure ◽  
Flow Solver ◽  
Reduced Order ◽  
Structure Interaction

A new method for fluid‐structure interaction (FSI) predictions is here introduced, based on a reduced-order model (ROM) for the structure, described by its mode shapes and natural frequencies. A linear structure is assumed as well as Rayleigh damping. A two-way coupling between the fluid and the structure is ensured by a loosely coupling staggered approach: the aerodynamic loads computed by the flow solver are used to determine the deformations from the modal equations, which are sent back to the flow solver. The method is first applied to a clamped beam oscillating under the effect of von Karman vortices. The results are compared to a full-order model. Then a flutter application is considered on the AGARD wing 445.6. Finally, the modal approach is applied to the aeroelastic behavior of an axial compressor stage. The influence of passing rotor blade wakes on the downstream stator blades is investigated.

Reduced-Order Modeling of Extreme Speed Turbochargers

2021 ◽  
Author(s):  
David W. Fellows ◽  
Daniel J. Bodony ◽  
Ryan C. McGowan
Keyword(s):  
Fluid Dynamic ◽  
Lagrange Equation ◽  
Structural Response ◽  
Numerical Data ◽  
Forced Response ◽  
Reduced Order Model ◽  
Order Model ◽  
Structural Dynamic ◽  
Reduced Order ◽  
And Performance

Abstract In order to improve their efficiency and performance, aircraft intermittent combustion engines often incorporate turbochargers that are adapted from ground-based applications. These turbochargers experience conditions outside of their design operating envelope and are found to experience high-cycle fatigue brought on by aerodynamically-induced blade resonances. The onset of fluid-structural interactions, such as flutter and forced response, in turbochargers at these conditions has not been extensively studied. A reduced-order model of the aeroelastic response of the turbine is developed using the Euler-Lagrange equation informed by numerical data from uncoupled computational fluid dynamic (CFD) and computational structural dynamic (CSD) calculations. The structural response of the reduced-order model is derived from a method of assumed modes approach. The unsteady fluid response is described by a modified version of piston theory as a first step towards including inhomogeneous aerodynamic forcing. Details of the reduced order model are given. The capability of the reduced-order model to predict the presence of flutter from a subset of the uncoupled numerical simulation data is discussed.

Sign in / Sign up

Export Citation Format

Share Document