Long Arc Shrouding—A Reliability Improvement for Untuned Steam Turbine Blading

1981 ◽  
Vol 103 (3) ◽  
pp. 522-527 ◽  
Author(s):  
R. J. Ortolano ◽  
J. A. La Rosa ◽  
W. P. Welch
Keyword(s):  
Steam Turbine ◽  
Arc Length ◽  
Variable Speed ◽  
Butt Welding ◽  
Reliability Improvement ◽  
Fatigue Failures ◽  
Short Arc ◽  
Turbine Blading ◽  
Turbine Exhaust

An approach to the design and modification of untuned variable speed steam turbine exhaust blading has been found to be highly successful in eliminating fatigue failures due to the first tangential in-phase mode resonance. The approach consists of butt-welding the shrouds on the short arc blade groups to form a substantially longer arc length. The result is a significant reduction in vibratory stress at resonant speeds. Because of the ease with which the approach can be implemented in the field, backfitting is highly attractive to turbine operators. Availability benefits to the marine, utility, petrochemical, refining, industrial and commercial fields are anticipated.

Eddy Current Damping: A Concept Study for Steam Turbine Blading

2009 ◽  
Author(s):  
Jacob Laborenz ◽  
Christian Siewert ◽  
Lars Panning ◽  
Jo¨rg Wallaschek ◽  
Christoph Gerber ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Eddy Current ◽  
Theoretical Models ◽  
Forced Response ◽  
Resonance Frequencies ◽  
Different Types ◽  
Stationary Test ◽  
Eddy Current Damping ◽  
Fatigue Failures ◽  
Turbine Blading

In gas and steam turbine applications a common approach to prevent the blades from high cycle fatigue failures due to high vibration amplitudes is the usage of friction damping elements. Besides the intended amplitude reduction this procedure also features some possibly unwanted side effects like a shift in resonance frequencies due to stiffening effects caused by the contact. Thus, as an alternative an eddy current based non-contacting damping concept for the application in turbo machinery is investigated. In this paper two different types of eddy current dampers are considered. Theoretical models for both are established by applying electromagnetic-mechanical theory. The theoretical models are compared to forced response measurements that are performed at a stationary test rig.

Eddy Current Damping: A Concept Study for Steam Turbine Blading

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Jacob Laborenz ◽  
Christian Siewert ◽  
Lars Panning ◽  
Jörg Wallaschek ◽  
Christoph Gerber ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Eddy Current ◽  
Theoretical Models ◽  
Forced Response ◽  
Resonance Frequencies ◽  
Different Types ◽  
Stationary Test ◽  
Eddy Current Damping ◽  
Fatigue Failures ◽  
Turbine Blading

In gas and steam turbine applications a common approach to prevent the blades from high cycle fatigue failures due to high vibration amplitudes is the usage of friction damping elements. Besides the intended amplitude reduction this procedure also features some possibly unwanted side effects like a shift in resonance frequencies due to stiffening effects caused by the contact. Thus, as an alternative an eddy current based noncontacting damping concept for the application in turbomachinery is investigated. In this paper two different types of eddy current dampers are considered. Theoretical models for both are established by applying electromagnetic-mechanical theory. The theoretical models are compared with forced response measurements that are performed at a stationary test rig.

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