Suppression of Subsynchronous Vibrations in a 11 MW Steam Turbine Using Integral Squeeze Film Damper Technology at the Exhaust Side Bearing

2016 ◽  
Author(s):  
Riccardo Ferraro ◽  
Michael Catanzaro ◽  
Jongsoo Kim ◽  
Michela Massini ◽  
Davide Betti ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Labyrinth Seal ◽  
Squeeze Film ◽  
Stable Operation ◽  
Steam Turbines ◽  
Squeeze Film Damper ◽  
Full Load ◽  
Steam Admission ◽  
Before And After ◽  
Full Speed

The presence of high subsynchronous vibrations and other rotordynamic instabilities in steam turbines can prevent operation at full speed and/or full load. The destabilizing forces generating subsynchronous vibrations can be derived from bearings, seals, impellers or other aerodynamic sources. The present paper describes the case of an 11 MW steam turbine, driving a syngas centrifugal compressor train, affected by subsynchronous vibrations at full load. After the occurrence of anomalous vibrations at high load and a machine trip due to the high vibrations, the analysis of data collected at the site confirmed instability of the first lateral mode. Further calculations identified that the labyrinth seal at the balance drum was the main source of destabilizing effects, due to the high pre-swirl and the relatively tight seal clearance. The particular layout of the turbine, a passing-through machine with a combined journal/double thrust bearing on the steam admission side, together with the need for a fast and reliable corrective action limited the possible solutions. Based on the analyses performed, adjusting the clearance and preload of the journal bearings could not have ensured stable operation at each operating condition. The use of swirl brakes to reduce the steam pre-swirl at the recovery seal entrance would have required a lengthy overhaul of the unit and significant labor to access and modify the parts. The final choice was a drop-in replacement of only the rear bearing (on the steam exhaust side) with a bearing featuring integral squeeze film damper (ISFD) technology. In addition to being a time efficient solution, the ISFD technology ensured an effective tuning of stiffness and damping, as proven by the field results. The analyses carried out to understand the source of the subsynchronous vibrations and to identify possible corrective actions, as well as the comparison of rotordynamic data before and after the application of the bearing with ISFD technology, are discussed.

Stabilizing a 46 MW Multistage Utility Steam Turbine Using Integral Squeeze Film Bearing Support Dampers

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Bugra Ertas ◽  
Vaclav Cerny ◽  
Jongsoo Kim ◽  
Vaclav Polreich
Keyword(s):  
Steam Turbine ◽  
Critical Speed ◽  
Stability Margin ◽  
Experimental Tests ◽  
Turbine Rotor ◽  
Squeeze Film ◽  
Full Load ◽  
Vibration Data ◽  
Full Speed ◽  
Full Load Operation

A 46 MW 5500 rpm multistage single casing utility steam turbine experienced strong subsynchronous rotordynamic vibration of the first rotor mode; preventing full load operation of the unit. The root cause of the vibration stemmed from steam whirl forces generated at secondary sealing locations in combination with a flexible rotor-bearing system. Several attempts were made to eliminate the subsynchronous vibration by modifying bearing geometry and clearances, which came short of enabling full load operation. The following paper presents experimental tests and analytical results focused on stabilizing a 46 MW 6230 kg utility steam turbine experiencing subsynchronous rotordynamic instability. The paper advances an integral squeeze film damper (ISFD) solution, which was implemented to resolve the subsynchronous vibration and allow full load and full speed operation of the machine. The present work addresses the bearing-damper analysis, rotordynamic analysis, and experimental validation through waterfall plots, and synchronous vibration data of the steam turbine rotor. Analytical and experimental results show that using ISFD improved the stability margin by a factor of 12 eliminating the subsynchronous instability and significantly reducing critical speed amplification factors. Additionally, by using ISFD the analysis showed significant reduction in interstage clearance closures during critical speed transitions in comparison to the hard mounted tilting pad bearing configuration.

scholarly journals Dynamic Performance of a Squeeze Film Damper with a Cylindrical Roller Bearing under a Large Static Radial Loading Range

Machines ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 14 ◽  
Author(s):  
Hans Meeus ◽  
Jakob Fiszer ◽  
Gabriël Van De Velde ◽  
Björn Verrelst ◽  
Wim Desmet ◽  
...  
Keyword(s):  
Roller Bearing ◽  
Squeeze Film ◽  
Stable Operation ◽  
Large Power ◽  
Squeeze Film Damper ◽  
Depth Analysis ◽  
Rotor Support ◽  
Cylindrical Roller Bearing ◽  
Radial Loading ◽  
Cylindrical Roller

Turbomachine rotors, supported by little damped rolling element bearings, are generally sensitive to unbalance excitation. Accordingly, most machines incorporate squeeze film damper technology to dissipate mechanical energy caused by rotor vibrations and to ensure stable operation. When developing a novel geared turbomachine able to cover a large power range, a uniform mechanical drivetrain needs to perform well over the large operational loading range. Especially, the rotor support, containing a squeeze film damper and cylindrical roller bearing in series, is of vital importance in this respect. Thus, the direct objective of this research project was to map the performance of the envisioned rotor support by estimating the damping ratio based on the simulated and measured vibration response during run-up. An academic test rig was developed to provide an in-depth analysis on the key components in a more controlled setting. Both the numerical simulation and measurement results exposed severe vibration problems for an insufficiently radial loaded bearing due to a pronounced anisotropic bearing stiffness. As a result, a split first whirl mode arose with its backward component heavily triggered by the synchronous unbalance excitation. Hence, the proposed SFD does not function properly in the lower radial loading range. Increasing the static load on the bearing or providing a modified rotor support for the lower power variants will help mitigating the vibration issues.

The Study of Deep-Hole Drilling BTA Drill Whirl Caused by Cutting Fluid

2015 ◽  
Vol 752-753 ◽  
pp. 466-472
Author(s):  
Zhen Ya Chen ◽  
Zhen Dong ◽  
Xiao Bin Huang ◽  
Yan Lan Li
Keyword(s):  
Reynolds Equation ◽  
Cutting Fluid ◽  
Squeeze Film ◽  
Hole Drilling ◽  
Deep Hole ◽  
Fluid Force ◽  
Deep Hole Drilling ◽  
Squeeze Film Damper ◽  
Before And After ◽  
Squeeze Effect

The relationships between drill speed, whirl, squeeze effect and fluid force drill suffered is got by using cutting fluid Reynolds equation. Principle of deep-hole drilling drill whirl is studied, pointing out the promotion of positive precession cutting fluid component is drill whirl’s reason. Simulated and studied of drill whirl round shape at different times, suggesting that only when BTA drill suffered by the fluid force, stable motion can be obtained. Analysis of the anti-precession of drill, and the squeeze film damper work principle is revealed. Comparative studied the movement of the drill by using MATLAB software simulation before and after adding squeeze film damper.

Stabilizing a 46 MW Multi-Stage Utility Steam Turbine Using Integral Squeeze Film Bearing Support Dampers

2014 ◽  
Author(s):  
Bugra Ertas ◽  
Vaclav Cerny ◽  
Jongsoo Kim ◽  
Vaclav Polreich
Keyword(s):  
Steam Turbine ◽  
Critical Speed ◽  
Stability Margin ◽  
Experimental Tests ◽  
Turbine Rotor ◽  
Squeeze Film ◽  
Full Load ◽  
Vibration Data ◽  
Multi Stage ◽  
Full Load Operation

A 46 MW 5,500 rpm multistage single casing utility steam turbine experienced strong subsynchronous rotordynamic vibration of the first rotor mode; preventing full load operation of the unit. The root cause of the vibration stemmed from steam whirl forces generated at secondary sealing locations in combination with flexible rotor-bearing system. Several attempts were made to eliminate the subsynchronous vibration by modifying bearing geometry and clearances, which came short of enabling full load operation. The following paper presents experimental tests and analytical results focused on stabilizing a 46 MW 6,230kg utility steam turbine experiencing subsynchronous rotordynamic instability. The paper advances an integral squeeze film damper (ISFD) solution, which was implemented to resolve the subsynchronous vibration and allow full load and full speed operation of the machine. The present work addresses the bearing-damper analysis, rotordynamic analysis, and experimental validation through waterfall plots, and synchronous vibration data of the steam turbine rotor. Analytical and experimental results show that using ISFD improved the stability margin by a factor of 12 eliminating the subsynchronous instability and significantly reducing critical speed amplification factors. Additionally, by using ISFD the analysis showed significant reduction in interstage clearance closures during critical speed transitions in comparison to the hard mounted tilting pad bearing configuration.

Investigation Into a “Steam Whirl” Which Affected HP Rotors of 300 MW Steam Turbines

2007 ◽  
Author(s):  
Janusz Kubiak Sz. ◽  
Dara Childs ◽  
M. Rodri`guez ◽  
J. C. Garci´a
Keyword(s):  
Steam Turbine ◽  
The Other ◽  
Steam Turbines ◽  
Full Load ◽  
The Past ◽  
Instability Effect ◽  
Valve Opening ◽  
Rotordynamic Forces ◽  
Rotor Model ◽  
Load Conditions

In the past, several 300 MW steam turbine rotors were affected by vibrations, which appeared at bearing #1 during load conditions. At certain loads, vibrations of the #1 bearing increased considerably. Near full load the amplitude of vibration sometimes reduced to acceptable levels. Practically, the phenomena were partially cured by trim balancing of the HP rotor, readjusting the valve opening characteristics and by correction of the clearances in the sealing system. The results are briefly summarized. On the other hand, the simulation of the various parameters using rotordynamic codes was conducted to explain the phenomena analytically. In this part, the rotordynamic rotor model was constructed and the following simulations were carried out: rotor bearing instability, effect of the destabilizing steam forces on the rotor at the first row, effect of the seal rotordynamic forces and the valve opening sequence on the rotor stability. All results were analyzed to present general conclusions.

Rotor Dynamic Analysis on Partial Admission Control Stage in a Large Power Steam Turbine

2010 ◽  
Author(s):  
Lin Gao ◽  
Yiping Dai
Keyword(s):  
Steam Turbine ◽  
Phase Angle ◽  
Low Frequency ◽  
Deep Understanding ◽  
Labyrinth Seal ◽  
Steam Turbines ◽  
Large Power ◽  
Stiffness Coefficients ◽  
Control Stage ◽  
Partial Admission

Partial admission is used widely for steam turbines to match their output power to the load demand. The occurrences or thresholds of most self-induced low-frequency vibrations are under partial admission conditions. But the destabilizing forces which cause rotor instability are seldom investigated under partial admission conditions especially for large power steam turbines. Full 3D CFD model is built for the control stage of a 600 MW steam turbine applying commercial codes. N-S equations are solved to investigate the flow fields in the control stage including all the blade passages and the labyrinth seal over the shroud. Interesting flow distributions are observed for the seal spaces at partial admission conditions. A correction formula is presented for partial admission labyrinth seal based on the classical one and a method is discussed for the estimation of partial-admission phase-angle-dependent stiffness coefficients. The destabilizing forces acting on the rotor system are calculated for different eccentricity angles and are compared with those under the concentric condition. The stiffness coefficients are solved under typical partial admission conditions. They are found to change dramatically with the phase angle. The results may be helpful for a deep understanding of the low-frequency variation problems of large power steam turbines under partial admission conditions.

Stability Characteristics of a Journal Bearing Mounted in an Uncentralized Squeeze Film Damper

1991 ◽  
Vol 113 (3) ◽  
pp. 584-589
Author(s):  
Yuichi Sato ◽  
H. Fujino ◽  
H. Sakakida ◽  
S. Hisa
Keyword(s):  
Steam Turbine ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
The Stability ◽  
Bearing Analysis

This paper describes the stability of a journal bearing mounted in an uncentralized squeeze film damper. It is known that mounting a journal bearing in a centralized squeeze film damper improves the bearing stability. From a practical viewpoint, however, it is difficult to centralize journal bearings which support a heavy rotor, such as a steam turbine. Experimentally, we show that a journal bearing can be stabilized by mounting in an uncentralized squeeze film damper. The effect of clearance of a squeeze film damper is investigated. By using short bearing analysis, rotor trajectories are calculated. Calculated results also shows stability improvement.

scholarly journals Nonlinear Response and Stability of an Experimental Overhung Compressor Mounted With a Squeeze Film Damper

2020 ◽  
Author(s):  
William J. Gooding ◽  
Matthew A. Meier ◽  
Edgar J. Gunter ◽  
Nicole L. Key
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Test Facility ◽  
Squeeze Film ◽  
Stable Operation ◽  
Static Structure ◽  
Squeeze Film Damper ◽  
Inertial Interaction ◽  
Rolling Element ◽  
Shaft Deflection

Abstract This paper presents rotordynamic data obtained within a test facility studying the aerodynamics of a high-speed centrifugal compressor for aero-engine applications. The experimental overhung compressor is supported by two rolling element bearings. The compressor-end ball bearing is supported by an oil-fed squeeze film damper. After some period of operation, the compressor began to exhibit a unique nonlinear increase in the rotordynamic response followed by an unexpected subsynchronous whirl instability as the speed continued to increase. Finally, as the rotor speed was increased further, the rotor re-stabilized. A numerical model of the compressor system was created using a commercially available software suite. This model indicates the effective weight of the damper support has a significant effect on the frequency of the second critical speed. Increasing this weight causes the second critical speed, originally predicted at 35,200 RPM, to shift down to 15,650 RPM. This increase in the support weight is due to inertial interaction between the damper support and the surrounding static structure. The increased shaft deflection that occurs as the rotor passes through this shifted critical speed causes the damper to lockup, resulting in the increased response observed experimentally. At a slightly higher speed, Alford-type aerodynamic cross-coupling forces excite the two subsynchronous critical speeds. Finally, as the rotor departs from the second critical speed, the damper unlocks and is able to effectively suppress the Alford-type instabilities, allowing the rotor to return to stable operation.

Thermally Sprayed Abradable Coatings in Steam Turbines: Design Integration and Functionality Testing

2010 ◽  
Author(s):  
Dieter Sporer ◽  
Scott Wilson ◽  
Petr Fiala ◽  
Ruediger Schuelein
Keyword(s):  
High Temperature ◽  
Steam Turbine ◽  
Gas Turbines ◽  
Labyrinth Seal ◽  
Test Methods ◽  
Steam Turbines ◽  
Coating Materials ◽  
Design Integration ◽  
Abradable Coatings ◽  
Thermally Sprayed

The concept of thermally sprayed abradable sealing technology has successfully been used in aero engines and industrial gas turbines for several decades now. More recently efforts were undertaken to implement the concept of seal coatings in steam turbine designs. As these typically use labyrinth type sealing, the application and test methods for sprayed seals applied to improve efficiency and reduce emissions need to be tailored to this particular seal configuration. This paper reviews how steam turbines can benefit from abradable coating technology and how it can be implemented into existing labyrinth seal designs for various seal locations in a steam turbine. A detailed review of high temperature rig abradability testing capabilities for labyrinth seal layouts using abradable coatings will be provided. Coating materials and their performance in a high temperature steam environment at 650 °C ( 1200 °F ) will be discussed. The application of coatings to various steam turbine components including large casings will be reviewed.

scholarly journals Demonstration of a Dynamic Clearance Seal in a Rotating Test Facility

2017 ◽  
Author(s):  
Andrew Messenger ◽  
Richard Williams ◽  
Grant Ingram ◽  
Simon Hogg ◽  
Stacie Tibos ◽  
...  
Keyword(s):  
Steam Turbine ◽  
High Speed ◽  
Labyrinth Seal ◽  
Test Facility ◽  
Steam Turbines ◽  
Rotor Position ◽  
Seal Design ◽  
Start Up ◽  
Steam Turbine Plant ◽  
Transient Events

The successful demonstration of the “Aerostatic Seal” in a half scale rotating facility is described in this paper. The Aerostatic seal is a novel dynamic clearance seal specifically designed for steam turbine secondary gas path applications. The seal responds to radial rotor excursions, so a reduced clearance can be maintained compared to conventional labyrinth seal without damage to the seal. This enables increased turbine performance through reduced leakage and increased tolerance of turbine transient events typically found during start up. The seal is an extension of the existing retractable seal design already deployed in commercial steam turbines. The seal was tested in the Durham Rotating Seals Rig, which was developed specifically to test this device. The rig featured a rotor designed to run with large eccentricities to model high speed radial rotor excursions, and the seal was instrumented to measure the real time seal response to the rotor. The experimental campaign has conclusively demonstrated the ability of the seal to dynamically respond to the rotor position. The key result is that the seal is able to track the rotor position at high speed, and hence maintain a mean seal clearance that is lower than the rotor eccentricity. Overall this work marks a key milestone in the development of the Aerostatic Seal, and leads the way to testing in a steam environment and application in steam turbine plant.

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