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Coating methods to increase material damping of compressor blades: measurements and modeling
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.ORCID iD: 0000-0001-5760-3919
2010 (English)In: Proceedings of ASME Turbo Expo 2010: Vol 6, Pts A and B, ASME Press, 2010, 1157-1165 p.Conference paper, Published paper (Refereed)
Abstract [en]

Methods are developed to improve damping of compressor blades, where unconstrained and constrained damping techniques are applied to the blades to increase material damping, displaying both measurement and modeling results. Two specimens, titanium and stainless steel, are treated by aluminum oxide and epoxy coating material. Measurements of material damping of simple beam specimens without and with treatments are carried out and results show that both treatments give damping increase, where aluminum treatment is more effective for damping improvement than the corresponding epoxy treatment. The unconstrained damping layer model is used to predict the total material damping of the combined structure as well as the material damping of coating layer. Comparisons with measured results are made. The constrained-layer model is also used to optimize the damping configuration and parametric analyses are performed. Two compressor blades in titanium and stainless steel are tested in air and vacuum conditions to measure material damping and results show that difference between air and vacuum situations exists. One reason is being that the radiation loss factor produced in air condition increases damping comparing with the damping in vacuum condition. The calculation of the radiation loss factor is performed to match the measurement data and results demonstrate that the radiation loss factor is one factor and air friction is another strong factor in this case. Finally, increasing material damping gives a contribution to decrease peak stress values and therefore increase the life time of compressor blades.

Place, publisher, year, edition, pages
ASME Press, 2010. 1157-1165 p.
Keyword [en]
Air conditions, Air friction, Aluminum oxides, Coating layer, Coating methods, Combined structure, Compressor blades, Damping layers, Epoxy coatings, In-vacuum, Life-times, Material damping, Measured results, Measurement data, Modeling results, One-factor, Parametric analysis, Peak stress, Radiation loss, Vacuum condition
National Category
Applied Mechanics
Identifiers
URN: urn:nbn:se:kth:diva-31159DOI: 10.1115/GT2010-23790ISI: 000290927800117Scopus ID: 2-s2.0-82055184855ISBN: 978-079184401-4 (print)OAI: oai:DiVA.org:kth-31159DiVA: diva2:402935
Conference
ASME Turbo Expo 2010: Power for Land, Sea, and Air, GT 2010; Glasgow; United Kingdom; 14 June 2010 through 18 June 2010
Note

QC 20110311

Available from: 2011-03-10 Created: 2011-03-10 Last updated: 2014-09-03Bibliographically approved
In thesis
1. Rotating Structure Modeling and Damping Measurements
Open this publication in new window or tab >>Rotating Structure Modeling and Damping Measurements
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The structural damping is of importance to suppress the vibration amplitude of compressor blades rotating at high angular velocity under a high cycle impact. To avoid the appearance of the high cycle fatigue (HCF), damping materials may be applied to the compressor blades. To quantify the effect while using damping materials, a numerical tool needs to be developed for the damping prediction of a dynamic rotating blade. This thesis is divided into two parts: Paper A develops a dynamic model of a rotating blade and Paper B a damping structure model including measurements.

In Paper A, a dynamic rotating blade model is developed by using a plate model at an arbitrary stagger angle. Hamilton’s principle is applied to derive a system of equations of motion and the corresponding boundary conditions. Numerical simulation is implemented to perform eigenfrequency analysis by the Extended Galerkin method. In addition, parametric analysis is performed with respect to rotation speed and stagger angle, respectively. Results show a good agreement with those of the finite element method. Finally, forced response analysis is determined for two cases; a point force and a distribution force, using a proportional damping model.

In Paper B, unconstrained and constrained damping techniques are applied to increase the structural damping of the blades, including measurement and modeling results. Two specimens, titanium and stainless steel, are treated by aluminum oxide and epoxy coating material. Measurement results show that both treatments give damping increase, where aluminum oxide is more effective for damping improvement than the corresponding epoxy treatment. The unconstrained damping layer model is used to predict the total material damping of the combined structure as well as the material damping of coating layer. Furthermore, the constrained-layer model is used to optimize the damping configuration. Two compressor blades in titanium and stainless steel are tested in air and vacuum. One reason is being that the radiation loss factor increases the total damping comparing with that under vacuum condition. The calculation of radiation loss factor is performed to match the measurement data. Finally, increased material damping decreases peak stress and therefore increases the life time of the compressor blades.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. 40 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2011:19
National Category
Fluid Mechanics and Acoustics Vehicle Engineering
Research subject
Järnvägsgruppen - Ljud och vibrationer
Identifiers
urn:nbn:se:kth:diva-31161 (URN)978-91-7415-916-5 (ISBN)
Presentation
2011-03-30, MWL 74, Teknikringen 8, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
TrenOp, Transport Research Environment with Novel Perspectives
Note

QC 20110311

Available from: 2011-03-11 Created: 2011-03-10 Last updated: 2013-02-15Bibliographically approved
2. Vibration Characteristics and Structural Damping of Rotating Compressor Blades
Open this publication in new window or tab >>Vibration Characteristics and Structural Damping of Rotating Compressor Blades
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Nowadays, the increasing demand on the high efficiency energy, low fuel consumption and environment friendly leads the turbomachinery to be operating under a critical high rotation speed at high temperature and pressure. This severe operation condition will definitely increase the probability of the occurrence of the high cycle fatigue. To reduce the risk of appearing high cycle fatigue, the structural damping of turbomachinery components has to be increased. Since the structural damping is always positive while the aerodynamic damping can be negative at some situation, increasing structural damping is nevertheless an interesting field in turbomachinery research. One efficient way of increasing damping is to treat damping material over the blade surface. Traditional damping materials, such as rubber, are not applicable in the severe operation environment. Therefore, hard coating material is applied due to its high stiffness and good sustainability in rough environments.

Numerical tools are developed to predict the structural damping of a dynamic rotating blade while varying several important designing parameters. Two types of rotating blades are modeled using the Hamilton’s principle: the straight blade by plate theory and pretwisted blade by shell theory. The extended Galerkin method and Chebyshev collocation method are applied for the numerical simulation, such as modal analysis and frequency response analysis. The parametric analysis is performed with respect to rotation speed, stagger angle, pretwisted angle, aspect ratio, etc. Proportional damping isused in all dynamic models to investigate the damping characteristics of the blades.

Alternatively, a multilayer rotating blade is modeled by a high order layerwise theory, where the validated results reveal the modal damping exchanges between modes dueto frequency loci veering and the influence of the damping configurations on the total damping of the multilayered structure. Finally, a commercial finite element software isused to predict the damping of a real compressor blade treated by the hard coating while varying the coating thickness and distributions.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. ix, 61 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2012:41
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-101241 (URN)978-91-7501-431-9 (ISBN)
Public defence
2012-09-07, K2, Teknikringen 28, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
TrenOp, Transport Research Environment with Novel Perspectives
Note

QC 20120827

Available from: 2012-08-27 Created: 2012-08-25 Last updated: 2013-04-11Bibliographically approved

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