Journal Bearings

Waukesha Bearings to Present at ASME Turbo Expo Virtual Conference

“Experimental Investigation and Numerical Modelling of a Large Heavily-Loaded Tilting Pad Journal Bearing With Polymer Lined Pads”

Authors

  • Filippo Cangioli, Waukesha Bearings (Presenting Author)
  • Richard Livermore-Hardy, Waukesha Bearings
  • Guy Pethybridge, Waukesha Bearings
  • Uemit Mermertas, Siemens Gas and Power GmbH & Co. KG
  • Michael Stottrop, Ruhr-Universitat Bochum
  • Beate Bender, Ruhr-Universitat Bochum

Presentation Schedule

Session 25-01
Start time: September 22, 2020, 10:15 am

Abstract

A large tilting pad journal (TPJ) bearing with “PEEK” polymer-lined pads was tested over a range of operating conditions representative of those experienced on turbo-generators used in fossil fuel power plants. The 500 mm diameter test bearing has four offset pivot pads, ball and socket pivots, load between pivot configuration, ‘Directed Lubrication’ and hydrostatic jacking features. The operating conditions explored during the test campaign characterize the static and dynamic behavior of the bearing over a range of shaft surface speeds between 40 m/s and 95 m/s and maximum specific load of 4.75 MPa. Similar test conditions were previously investigated on the same bearing with whitemetal lined pads, allowing for a direct comparison.

A thermo-elasto-hydrodynamic (TEHD) model for TPJ bearings with polymer-lined pads is introduced in this paper and validated against experimental test data.

Experimental data along with numerical results reveal and confirm the superior performance that can be attained using TPJ bearings with polymer-lined pads at high specific loads.

Read more about the paper on the ASME Turbo Expo site

Conference Registration

ASME Turbo Expo Virtual Conference registration details can be found online at the ASME website

Virtual event content will be available on-demand approximately one week prior to, during and after the virtual event conference dates.

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Waukesha Bearings Patents Trailing Edge Cooling

Waukesha Bearings, a global leader in the design and manufacture of engineered hydrodynamic bearings, has secured a patent for its innovative trailing edge cooling technology. Trailing edge cooling increases heat transfer in tilting pad bearings to expand bearing operating limits. The design features grooves in the trailing edge face of the tilting pad and a spray bar adjacent to the trailing edge to deliver cooling flow.

The grooves in the trailing edge face increase the surface area and allow the lubricant to penetrate deeper into the pad for greater cooling effect. The flow supplied to the trailing edge is a portion of the flow already being supplied to lubricate the bearing for hydrodynamic operation.

The inventors on the patent, US 9,534,637 B2, are Richard Livermore-Hardy, Engineering Manager, Europe, and Barry Blair, Chief Engineer. Livermore-Hardy is based out of the Waukesha Bearings office in Rickmansworth, UK; Blair is based out of the company’s Pewaukee, WI, USA, office.

Read the full text of the patent on the U.S. Patent and Trademark Office website

“The development of trailing edge cooling is rooted in the specific need of our customers to address high bearing temperatures, which can limit the operational range of a bearing,” said Marcell Ulrichs, President of the company. “This patent is representative of our commitment to combine innovation and engineering to create a best-in-class bearing solution.”

One of the leading applications of trailing edge cooling technology is on the Waukesha Bearings Maxalign® tilt pad radial bearing. Optimized for performance in large rotating equipment, Maxalign bearings offer reduced oil flow and power loss to improve machine efficiency; a pivot design highly adaptable to shaft misalignment; and an industry leading hydrostatic lift design in the lower pads that produces a reliable shaft lift whilst limiting the temperature increase that the hydrostatic lift feature can induce once the machine has reached full speed. The application of trailing edge cooling in the Maxalign design further lowers bearing temperatures, permitting operating speeds and loads in excess of 100 m/s and 3 MPa, without compromising bearing life or safety margin.

Read more about the Maxalign tilt pad radial bearing

Trailing edge cooling is not limited to the Maxalign bearing design. Any radial or thrust bearing operating under higher speeds and loads than typically allowed would benefit from trailing edge cooling. Contact Waukesha Bearings to learn how trailing edge cooling technology could benefit your application.

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MLSF Bearings Provide Longer Life, Low Maintenance, Minimal Downtime

Waukesha Bearings, a global leader in the design and manufacture of oil- and process-lubricated engineered bearings, is proud to announce the availability of its Multi-Lobe Semi-Floating (MLSF®) bearings. The unique MLSF technology, which improves stability and reliability compared to conventional floating ring bearings, can extend the life of host equipment and surrounding parts.

“Our MLSF design is specifically engineered to minimize vibrations, which promotes longer-lasting equipment and lessens the likelihood of early failures in the turbocharger or downstream equipment,” said Ken Bischof, Senior Development Engineer at Waukesha Bearings. “A failed bearing can lead to downtime for a replacement bearing, or worse, replacement of related equipment. A bearing system operating at an optimized temperature, which is cool enough to prevent coking yet hot enough to maintain optimum viscosity, can minimize both downtime and power loss.”

By designing the MLSF bearing system to operate at optimized temperatures with minimal vibrations, the life of the equipment and surrounding parts is extended. In addition to global customer service and Waukesha Bearings’ proven results, the MLSF bearings offer an ideal solution for smaller, high-speed turbomachinery, as well as for turbochargers in large diesel or natural gas engines.

Read more about MLSF bearings

Waukesha Bearings’ MLSF bearings, available for use with shafts as small as 0.5 inches in a single bearing or cartridge, can handle a static unit load as light as 10 psi (.07MPa) to a dynamic unit load exceeding 700 psi (4.8 MPa). The MLSF, which can handle multi-viscosity oils, is engineered to accommodate temperature ranges up to 300ºF (149ºC) with even higher temperatures available. The first Waukesha Bearings MLSF bearing, which has been in field operation for more than 30,000 hours, continues to surpass competitive bearing performance of only 500 hours in the same application.

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Bearings Reduce Spiral Vibration on Turbo-generators

With the industry trending toward improved efficiency, in both new and existing equipment, higher demands are placed on the equipment and the bearings.

When Alstom Power identified a phenomenon of spiral vibration close to the trip level on one of their 450MVa hydrogen-cooled generators, our proprietary predictive tools and extensive industry experience on equipment of this size made Waukesha Bearings the clear choice to design and manufacture a drop-in bearing replacement.

More than 13 generator sets have been commissioned since the initial phenomenon was detected in 2003. In total, the Maxalign bearings have seen 600,000 cumulative operating hours with these particular Alstom generators.

Read the full article on page 21 of International Power Engineeringmagazine, or download the article below.

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Have a Pump, Motor, Generator, Turbine, Compressor or Gearbox? There’s a Bearing for That!

Waukesha Bearings is known internationally for its capabilities, technology, size and application experience in the rotating (turbo) equipment industry.

Download our article from the October 2012 issue of Power Transmission Engineering for a brief selection guide intended to assist engineers, specifiers, integrators and others in choosing the right bearing—and bearing technology—for the application.

Download the Article

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Next-Generation Bearing Technology for Gas-Fired Power Stations

In the May 2010 issue of International Power Engineer, Jessica Whelan and Richard Livermore-Hardy look at new large tilting pad radial bearings designed to further improve safety margins.

It is difficult to pick up an industry publication without seeing an article or viewpoint covering the trend away from coal toward natural gas as part of the global power generation mix.

Whether climate-change legislation happens this year, in 2011 or in 2020, project owners and financiers at the very least are ‘cautious on coal.’  This shift toward cleaner energy is creating increased focus on alternative fuel sources; nuclear energy and the many forms of renewable energy are the targets of technology development, investment and new business ventures.

However, in the short to mid-term, natural gas-driven power generation is the obvious substitute for coal as the economy recovers…as GDP grows, so does the demand for energy.

This move toward natural gas as a primary source of energy has placed new demands on the makers of gas-fired combustion turbines.  Larger, lower emission, and more reliable and efficient machines are required if turbines are to play a more vital role in the global power mix.

In anticipation of these market demands, Waukesha Bearings, a leader in hydrodynamic bearings and magnetic bearing systems, has developed the next generation of large tilting pad radial bearing designs to further improve safety margins and provide superior performance to address the challenges associated with these machines.

The next generation technology was applied to Waukesha’s existing ball and socket tilting pad radial bearing with Directed Lubrication, which has been used successfully over the past 25 years in large frame gas turbines, steam turbines and turbo-generators. Throughout the development cycle, Waukesha engineers worked closely with leading original equipment manufacturers to translate turbine performance requirements into improved bearing designs using a combination of field experience, testing and advanced analysis techniques.

In order to directly address requirements for improved machine efficiency, Waukesha’s latest design uses an efficient 4-pad arrangement to minimise power loss and reduce the number of components.

As a result of the trend towards larger machines, higher bearing loads and surface speeds, the design also includes an optimised pad and hydrostatic jacking groove design to further reduce pad temperatures, leading to increased safety margins and machine reliability.

The latest technology compliments Waukesha’s proven ball and socket pivot design, which, due to the proprietary design and materials, has excellent dynamic alignment capability typically required on ‘hot’ machines during the transition from cold to hot conditions plus high stiffness for assured bearing dynamic characteristics.

Waukesha engineers used proprietary predictive tools and testing to design and verify the performance of the next generation of large tilting pad radial bearing designs, which have now been in service for several years on numerous gas-fired combined cycle turbo-generator applications.

The knowledge gained during this process will allow Waukesha to further adapt their technology for the ever increasing requirements for improved performance and reliability in the gas-fired power generation market.

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Bearing Design Reduces Performance Variability

Tight-tolerance tilt pad journal bearings provide increased stability in high speed turbomachinery equipment.

By Dr. Kenneth R. Bischof
Published in International Oil & Gas Engineer, 2009

As machinery builders strive for improved efficiency, higher pressure ratios or increased operational flexibility, static performance and rotordynamic challenges become even greater for rotor-bearing system engineers. Often these challenges are a direct result of a more flexible rotating system and increased rotor length, leading to increased bearing spans.

To combat these challenges, fluid film bearing engineers have traditionally relied on a variety of features within a tilt pad journal bearing, such as assembled clearance, pad-angle, pre-load and pivot offset. When traditional feature variations are not sufficient for more challenging systems, bearing structural stiffness and damping have also been improved through the use of higher performing ball-and-socket pivot designs as well as employing squeeze-film dampers, respectively.

System rotordynamic challenges have placed an increased emphasis on reliably maintaining tight tolerances within bearing manufacturing processes. Even the slightest tolerance variations can have dramatic impact on bearing stiffness and damping characteristics, ultimately leading to differences between  predicted and actual performance of the machine.

Early in 2008 Waukesha Bearings completed development of a new bearing design aimed at solving many of the technical issues surrounding the dynamic performance of the rotor-bearing system. This new design utilises a patent-pending, single-piece frame construction with the tilt pads integral to the shell and without sacrificing pivot stiffness, creating a potential fatigue-failure point or restricting free-tilt of the journal pads. This is accomplished through the use of an EDM manufacturing process used in combination with a hardened steel pivot, offering a solution with reduced pad flutter, particularly in unloaded pads, and less vibration, fatigue and wear. The bearing is also designed with a secondary integral pad stop that prevents over-rotation as well as improved oil distribution across the pads.

To read the complete article, download the PDF below.

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