G1000-2-4 Effect of Material Damping on Flutter of Steam Turbine Vane

The vane used in a low pressure end of steam turbine is usually fixed to shroud and casing by welding both ends. In such a vane structure, the damping in loading operation is comprised of the material damping and the aerodynamic damping, because the structural damping is very small. In this paper, first, the vane is modeled by the uniform beam fixed at both ends, and the effect of the material damping on the vane flutter is studied. In the stability analysis, the simple one-degree-of-freedom model is applied, where the linear aerodynamic model is used. In other words, it is assumed that the aerodynamic force due to the working fluid is proportional to the vane velocity and the negative damping coefficient does not change with amplitude. The allowable aerodynamic damping for the vane flutter is calculated and compared for the solid vane and the hollow vane. In addition, the vibration analysis of the actual steam turbine vane is carried out by 3D FEA (Finite Element Analysis), and the material damping of the solid and hollow vane is calculated by use of the results by FEA. The stability of the solid vane and the hollow vane on the flutter is also evaluated by use of the results calculated by FEA. From these results, the material damping characteristics of the steam turbine vane are clarified, as well as the effect of the material damping of the steam turbine vane on the flutter suppression.

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Damping Identification and its Comparison for Various Types of Blade Couplings

Volume 7A: Structures and Dynamics ◽

10.1115/gt2013-95438 ◽

2013 ◽

Author(s):

Zdenek Kubin ◽

Vaclav Polreich ◽

Vaclav Cerny ◽

Petra Babkova ◽

Lubos Prchlik

Keyword(s):

Steam Turbine ◽

Damping Ratio ◽

Nonlinear Behavior ◽

Mode Shapes ◽

Material Damping ◽

Blade Vibration ◽

Friction Dampers ◽

Linear Behavior ◽

Disc Rotation ◽

Identification Technique

Regarding steam turbine blade vibrations, damping of blade as well as bladed disc mode shapes is one of the most important parameters in terms of steam turbine operation. A value of the parameter depends on properties of material used for manufacturing and construction elements of the blades and the discs such as blade roots, shrouds, tiebosses (snubbers) and dampers. This article deals with a comparison of damping of mode shapes for particular blade couplings and shows which methods are suitable for determination of the damping in individual cases. The whole identification procedure of the damping together with its specifics is also presented. At first, an identification technique of material damping ratio is introduced and its results are given for different materials. The material damping ratio is assessed as material strain dependent. Subsequently, damping ratio of bladed disc mode shapes under bladed disc rotation is identified taking into account two alternatives. The alternatives differ in such a way that blades have been free for the first time and then coupled with friction dampers. Outcomes presented in the article illustrate good agreement between damping ratio of bladed disc mode shapes with free blades and material used for manufacturing of the blades. On the other hand, damping ratio of bladed disc mode shapes with friction dampers is significantly different and strongly dependent on blade vibration amplitudes as well as nodal diameters of bladed disc mode shapes. Finally, nonlinear behavior of the bladed disc has been revealed along large blade vibration amplitudes and higher nodal diameters of the disc. The non-linear behavior manifests itself in such a way that values of natural frequencies of the disc have become dependent on blade vibration amplitudes.

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Analysis and Verification Test of Damping Characteristics of Steam Turbine Hollow Vane With Friction Damper

Volume 7A: Structures and Dynamics ◽

10.1115/gt2014-25157 ◽

2014 ◽

Author(s):

Yasutomo Kaneko ◽

Hiroyuki Yamashita ◽

Hiroharu Ooyama

Keyword(s):

Steam Turbine ◽

High Capacity ◽

Analysis Method ◽

Structural Damping ◽

Friction Damper ◽

Flat Plates ◽

Aerodynamic Damping ◽

Damping Characteristics ◽

Excited Vibration ◽

Turbine Vane

A vane used in a low pressure end of a steam turbine is usually fixed to a shroud and a casing by welding both ends. In such a vane structure, the damping in loading operation is comprised of the material damping and the aerodynamic damping, because the structural damping is very small. In the blade and vane of high-capacity steam turbine units, the aerodynamic damping may become negative under the high loading operation, and some papers reported the self-excited vibration of the blade and vane caused by the negative aerodynamic damping. Recently, in order to increase the reliability of the steam turbine vane, a hollow vane with a friction damper has been proposed. In such a steam turbine vane, the curved damper piece made of the thin plate is inserted into the hollow vane, and the structural damping is added by use of the friction between the damper piece and the vane. In this paper, for the purpose of clarifying the damping characteristics of the hollow vane with the friction damper, first, the excitation test of the model vane is carried out. In the excitation test of the model vane, the damping characteristics of the model vane consisting of two flat plates and the thin curved damper piece are measured, changing the excitation force. Second, the analysis method for predicting the damping characteristics of the hollow vane with the friction damper, which utilizes the conventional modal analysis method and the harmonic balance method, is proposed. The validity of the analysis method is verified by comparing the measured damping with the calculated ones. After verifying the analysis method, the actual steam turbine hollow vane with the friction damper is also analyzed, and the effect of the damper stiffness on the damping characteristics is examined. Finally, the actual hollow vane with the friction damper for the high-capacity steam turbine unit is designed and manufactured, and the excitation test of the actual hollow vane is carried out. From these results, the damping characteristics of the hollow vane with the friction damper are clarified.

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Application of numerical modelling for determining the optimal position of the suction slot in the steam turbine vane cascade

Journal of Physics Conference Series ◽

10.1088/1742-6596/1683/2/022067 ◽

2020 ◽

Vol 1683 ◽

pp. 022067

Author(s):

V G Gribin ◽

A A Tishchenko ◽

R A Alekseev ◽

I Yu Gavrilov ◽

V V Popov ◽

...

Keyword(s):

Numerical Modelling ◽

Steam Turbine ◽

Optimal Position ◽

Turbine Vane ◽

Suction Slot

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F211 STUDY ON VIBRATION RESPONSE OF STEAM TURBINE VANE WITH HALF RING STRUCTURE(Steam Turbine-4)

The Proceedings of the International Conference on Power Engineering (ICOPE) ◽

10.1299/jsmeicope.2009.2._2-499_ ◽

2009 ◽

Vol 2009.2 (0) ◽

pp. _2-499_-_2-504_

Author(s):

Yasutomo KANEKO ◽

Kazushi MORI

Keyword(s):

Steam Turbine ◽

Ring Structure ◽

Vibration Response ◽

Turbine Vane

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Inlet Flux Influence to Aerodynamic Performance of Steam Turbine Vane Cascade

Advance Journal of Food Science and Technology ◽

10.19026/ajfst.6.197 ◽

2014 ◽

Vol 6 (12) ◽

pp. 1282-1286

Author(s):

Feng Zi-Ming ◽

Ding Huanhuan ◽

Li Chunhong ◽

Xu Ping

Keyword(s):

Steam Turbine ◽

Aerodynamic Performance ◽

Turbine Vane

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Vortexing Methods to Reduce Secondary Losses in a Low Reaction Industrial Turbine

Volume 2A: Turbomachinery ◽

10.1115/gt2015-43235 ◽

2015 ◽

Cited By ~ 1

Author(s):

Srikanth Deshpande ◽

Marcus Thern ◽

Magnus Genrup

Keyword(s):

Steady State ◽

Steam Turbine ◽

Pressure Loss ◽

Total Pressure ◽

Stokes Equations ◽

Navier Stokes ◽

Blade Design ◽

Navier Stokes Equations ◽

Commercial Code ◽

Turbine Vane

Vortexing methods implemented on an industrial steam turbine vane in order to reduce secondary losses are discussed. Three vortexing methods presented are prismatic blade design, inverse vortex and parabolic forced vortex. Baseline industrial vane considered for study is a prismatic blade design. Modifications are analysed numerically using commercial code CFX. Modified vanes along with baseline rotor as a complete stage is considered for analysis. Steady state Reynolds averaged Navier Stokes equations are solved. Total pressure loss (TPL) is used as target functions to monitor reduction in secondary losses. Rotor considered for the study is the baseline industrial rotor for all design modifications of vane.

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