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COUPLED FLUID STRUCTURE SIMULATION METHOD IN THE FREQUENCY DOMAIN FOR TURBOMACHINERY APPLICATIONS

Berthold, Christian and Frey, Christian and Schönenborn, Harald (2018) COUPLED FLUID STRUCTURE SIMULATION METHOD IN THE FREQUENCY DOMAIN FOR TURBOMACHINERY APPLICATIONS. In: Proceedings of the ASME Turbo Expo. Proceedings of ASME Turbo Expo 2018, June 11 - 15, 2018, Oslo.

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Abstract

Turbomachinery components are exposed to unsteady aero- dynamic loads which must be considered during the design pro- cess to ensure the structural mechanical integrity. There are two primary mechanisms which cause structural vibrations and can lead to high-cycle fatigue due to high dynamic stresses: flutter (self-excited vibrations) and forced response (forced excitation, e.g. wakes from upstream blade rows). In this work an emerging numerical frequency-domain method which is designed to effi- ciently simulate coupled fluid-structure interaction (FSI) prob- lems considering nonlinearities in the flow and structure is mod- ified and applied to an academic and a realistic test case. Fur- thermore complex structural eigenmodes are considered instead of purely real modes as was demonstrated in the literature so far. This method is able to predict limit cycle oscillations and forced response amplitudes. The coupled solver uses the Har- monic Balance (HB) method with an alternating frequency time approach to model periodically unsteady flows and structure dy- namics. The resulting nonlinear HB equations of the flow are solved with a pseudo-time stepping method while the nonlinear HB equations of the structure are solved with a Newton method. The dynamics of the involved structure are further simplified by considering only one relevant eigenmode of the structure. The method is applied to a 3D axial turbine configuration with a mod- ified Youngs modulus for the material of the blisk. The standard flutter curve of the blade row shows that at least one eigenmode is aerodynamically unstable at certain nodal diameters. As a first model test case for the harmonic balance solver, the non- linear structural damping is defined as a cubic modal damping term. The results of the frequency-domain method are compared to coupled FSI simulations in the time domain. The analysis shows that the frequency-domain method is very promising in terms of both computational efficiency and accuracy.

Item URL in elib:https://elib.dlr.de/120686/
Document Type:Conference or Workshop Item (Speech)
Title:COUPLED FLUID STRUCTURE SIMULATION METHOD IN THE FREQUENCY DOMAIN FOR TURBOMACHINERY APPLICATIONS
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Berthold, ChristianChristian.Berthold (at) dlr.deUNSPECIFIED
Frey, ChristianChristian.Frey (at) dlr.deUNSPECIFIED
Schönenborn, HaraldMTU Aero Engines GmbHUNSPECIFIED
Date:2018
Journal or Publication Title:Proceedings of the ASME Turbo Expo
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:No
Series Name:Turbomachinery Technical Conference and Exposition
Status:Published
Keywords:FSI, Turbomachinery, Flutter, Harmonic Balance, Fluid Structure Interaction
Event Title:Proceedings of ASME Turbo Expo 2018
Event Location:Oslo
Event Type:international Conference
Event Dates:June 11 - 15, 2018
Organizer:ASME
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:other
DLR - Research area:Aeronautics
DLR - Program:L - no assignment
DLR - Research theme (Project):L - no assignment
Location: Köln-Porz
Institutes and Institutions:Institute of Propulsion Technology > Numerical Methodes
Deposited By: Berthold, Christian
Deposited On:29 Jun 2018 09:04
Last Modified:29 Jun 2018 09:04

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