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General shell model for a rotating pretwisted blade
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: 0000-0002-3609-3005
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.ORCID iD: 0000-0001-5760-3919
2013 (English)In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 332, no 22, 5804-5820 p.Article in journal (Refereed) Published
Abstract [en]

A novel dynamic model for a pretwisted rotating compressor blade mounted atan arbitrary stagger angle using general shell theory and including the rotationalvelocity is developed to study the eigenfrequencies and damping properties of thepretwisted rotating blade. The strain-displacement relation and constitutive modelbased on the general (thick) shell theory are applied to bring out the strain energyof the rotating blade. Using the Hamilton’s principle, the variational form of thetotal energy is derived in order to obtain the corresponding weak form for thenumerical simulation. The model is validated by comparing to literature resultsand Ansys results, showing good agreement. Parametric analyses are carried outto study the influence of the rotation velocity, the stagger angle and the radius ofthe disk on the eigenfrequencies of the pretwisted blade. Proportional dampingis included into the proposed model to investigate the influence of rotational velocityon the damping characteristics of the pretwisted rotating blade system. It isshown that, due to inertial and Coriolis eects, damping decreases as the rotation velocity increases for the lower part of the velocity range considered and eitherdecreases or increases depending on the mode order for higher velocities. Furthermore,frequency loci veering as a result of the rotation velocity is observed.The proposed model is an ecient and accurate tool for predicting the dynamicbehavior of compressor blades of arbitrary thickness, stagger angle and pretwist,potentially during the early designing stage of turbomachinery.

Place, publisher, year, edition, pages
Elsevier, 2013. Vol. 332, no 22, 5804-5820 p.
Keyword [en]
Rotating pretwisted blade, Shell theory, Damping prediction
National Category
Applied Mechanics
Identifiers
URN: urn:nbn:se:kth:diva-101239DOI: 10.1016/j.jsv.2013.06.025ISI: 000323361000010ScopusID: 2-s2.0-84880923598OAI: oai:DiVA.org:kth-101239DiVA: diva2:546883
Funder
Swedish Energy Agency
Note

QC 20130723

Available from: 2012-08-25 Created: 2012-08-25 Last updated: 2013-09-12Bibliographically approved
In thesis
1. 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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