In the early 1980s, Siemens developed a last stage fast rotating condensation blading (SK) blade with strongly twisted and tapered profiles for industrial condensing steam turbines, which operate with variable speed under high steam mass flow and excessive condensing pressures. To suppress alternating stresses of the lowest blade resonances, conical friction bolts are loosely mounted at the upper parts of adjacent airfoils. Also, these bolts couple the rotating blades, since steam excitation is lower than the friction threshold force on the bolt contacts. These coupling and damping capabilities were proven experimentally for the smallest SK blade at the test rig of the real turbine. By considering the similar mechanical and aerodynamic characteristics based on the tested smallest airfoil, the entire SK-blade family has been scaled up for reliable utilization in more than 500 industrial turbines operating for diverse ranges of power and speed. A recent trend to very large compression units, like gas to liquids, acid terephtalic, or methanol plants, imposes a need for further enlargement of the SK-blade family and its friction bolt, whose mechanical properties have been proven experimentally for the smallest airfoil. In this paper, the mechanical capabilities of the smallest and large SK blades coupled by the bolts are verified by using the finite element (FE) method. The static analyses with friction sliding on airfoil interfaces and the linear dynamic behavior of tuned disk assemblies are considered. The FE mesh quality and the proper boundary conditions at the radial fork root are accomplished by getting good agreements between the computed and measured resonance frequencies of the large freestanding blade at standstill. The validated mesh refinement and root boundary conditions are used further in all numerical FE analyses. For the large SK-disk assembly under spin-pit conditions, the obtained FE results are in very good agreement with the experimental Campbell diagrams, which are measured with the three gauges that also identify the stick-slip and stuck bolt’s contact conditions. Concerning the gauge outputs and the FE steady-state blade resonances computed for the analytically determined air jet excitation, the experimental spin-pit results demonstrate that the bolts are mainly in stuck contact conditions. Only in very narrow frequency ranges around resonance peaks, microslips on the bolts occur due to the resonance amplification of blade vibrations. This is proven indirectly by comparison of the overall damping values evaluated from the blade resonances at standstill and in the spin pit. The described linear dynamic concept assesses properly static stresses and free vibrations of the scaled disk assembly with friction bolts. For the steam excitation, which generates dynamic contact reactions bigger than the friction threshold forces, the realistic blade responses need to be obtained from the blade simulation with friction (Szwedowicz, J., Secall-Wimmel, T., and Duenck-Kerst, P., 2007, “Damping Performance of Axial Turbine Stages With Loosely Assembled Friction Bolts; the Non-Linear Dynamic Assessment; Part II,” Proceedings of ASME Turbo Expo 2007, Montreal, Canada, May 14–17, ASME Paper No. GT2007-27506).
Skip Nav Destination
e-mail: jaroslaw.szwedowicz@ch.abb.com
e-mail: peter.duenck-kerst@siemens.com
e-mail: david.regnery@siemens.com
Article navigation
Research Papers
Scaling Concept for Axial Turbine Stages With Loosely Assembled Friction Bolts: The Linear Dynamic Assessment
J. Szwedowicz,
e-mail: jaroslaw.szwedowicz@ch.abb.com
J. Szwedowicz
Thermal Machinery Laboratory
, ABB Turbo Systems Ltd., CH-5401 Baden, Switzerland
Search for other works by this author on:
Th. Secall-Wimmel,
Th. Secall-Wimmel
Thermal Machinery Laboratory
, ABB Turbo Systems Ltd., CH-5401 Baden, Switzerland
Search for other works by this author on:
A. Sonnenschein,
e-mail: peter.duenck-kerst@siemens.com
A. Sonnenschein
Power Generation/Industrial Applications
, Siemens AG, D-47053 Duisburg, Germany
Search for other works by this author on:
D. Regnery,
e-mail: david.regnery@siemens.com
D. Regnery
Power Generation/Service Steam Turbines
, Siemens AG, D-45473 Muelheim/Ruhr, Germany
Search for other works by this author on:
M. Westfahl
M. Westfahl
Search for other works by this author on:
J. Szwedowicz
Thermal Machinery Laboratory
, ABB Turbo Systems Ltd., CH-5401 Baden, Switzerlande-mail: jaroslaw.szwedowicz@ch.abb.com
Th. Secall-Wimmel
Thermal Machinery Laboratory
, ABB Turbo Systems Ltd., CH-5401 Baden, Switzerland
A. Sonnenschein
Power Generation/Industrial Applications
, Siemens AG, D-47053 Duisburg, Germanye-mail: peter.duenck-kerst@siemens.com
D. Regnery
Power Generation/Service Steam Turbines
, Siemens AG, D-45473 Muelheim/Ruhr, Germanye-mail: david.regnery@siemens.com
M. Westfahl
J. Eng. Gas Turbines Power. May 2008, 130(3): 032504 (12 pages)
Published Online: April 3, 2008
Article history
Received:
July 3, 2007
Revised:
November 9, 2007
Published:
April 3, 2008
Citation
Szwedowicz, J., Secall-Wimmel, T., Dünck-Kerst, P., Sonnenschein, A., Regnery, D., and Westfahl, M. (April 3, 2008). "Scaling Concept for Axial Turbine Stages With Loosely Assembled Friction Bolts: The Linear Dynamic Assessment." ASME. J. Eng. Gas Turbines Power. May 2008; 130(3): 032504. https://doi.org/10.1115/1.2838995
Download citation file:
Get Email Alerts
Cited By
Heat Release Characteristics of a Volatile, Oxygenated, and Reactive Fuel in a Direct Injection Engine
J. Eng. Gas Turbines Power
Comprehensive Life Cycle Analysis of Diverse Hydrogen Production Routes and Application on a Hydrogen Engine
J. Eng. Gas Turbines Power
Related Articles
Damping Performance of Axial Turbine Stages With Loosely Assembled Friction Bolts: The Nonlinear Dynamic Assessment
J. Eng. Gas Turbines Power (May,2008)
On Nonlinear Forced Vibration of Shrouded Turbine
Blades
J. Turbomach (January,2008)
Effects of Damping and Varying Contact Area at Blade-Disk Joints in Forced Response Analysis of Bladed Disk Assemblies
J. Turbomach (April,2006)
Eddy Current Damping: A Concept Study for Steam Turbine Blading
J. Eng. Gas Turbines Power (May,2010)
Related Proceedings Papers
Related Chapters
Data Tabulations
Structural Shear Joints: Analyses, Properties and Design for Repeat Loading
Fatigue Analysis in the Connecting Rod of MF285 Tractor by Finite Element Method
International Conference on Advanced Computer Theory and Engineering, 4th (ICACTE 2011)
Environment Assisted Cracking of Steam Turbine Blade Steels – A Consistent Rationalization Based on Hydrogen Assisted Cracking
International Hydrogen Conference (IHC 2012): Hydrogen-Materials Interactions