Examples of research and development at KMIP Department aimed at improving ecological safety of water turbines

INTRODUCTION

  • Increasing requirements for environmental protection, new materials and designs necessary
  • Hydroelectric power plants in direct contact with water reservoirs and rivers are potentially endangering water cleanliness, hence they should also be modernized in the way minimizing the environmental hazards
  • A lot of progress in this field in last decades, but still much work to be done: modifications are not straightforward require know-how and/or new research
  • Two faculties at GUT do research in the field of bearing systems. Teams are involved in the research of water lubricated or self-lubricating bearings for various applications, including hydropower

Two basic types of bearings in hydro applications require different approaches:

  • Low speed bearings in which mixed lubrication conditions exist – guide vanes bushes, rotor blade bushes, etc. Application of properly selected self-lubricating material allows for eliminating grease as a lubricant. Material selection and bearing design, along with reliable durability prediction is not a straightforward task, especially as the bearings operate in atypical conditions of small oscillations
  • High speed bearings – fluid film lubrication possible, modifications focused on substituting mineral based lubricants (mineral oils) with eco-friendly lubricants, preferably with water. Water lubrication creates numerous problems including material issues and low carrying capacity of water lubricated

 

EXAMPLE 1: HIGH SPEED BEARINGS

High load capacity ceramic bearing

  • Bearing is submerged directly in water – no filtration needed
  • Almost conformal contact of sliding elements allows to filter water contamination
  • Greater load capacity especially for low speed
  • Nominal average pressure of the film were changed from 0-5 MPa, but in several cases 10 MPa was exceeded

Next generation water lubricated FB

  • Elastic sliding top foil is supported directly on rigid housing
  • On both sides of housing there are chamfers filled with elastic material
  • Inside the rigid housing there is a pocket filled with elastic material (in case of one direction of load)
  • The structure and idea of the bearing is patented P.400897

Prototype bearing prepared for experimental tests:

Direct contact: Dr Artur Olszewski: aolszews@pg.edu.pl

 

EXAMPLE 2: GREASELESS MATERIALS FOR GUIDE VANES

After measurements of micro movements of guide vane bushes in five large Polish power plants, we realized that large part of the sliding motion occurs during small oscillations because of vibrations.

Test rig (SOOG) with a continuous measurement of instantaneous friction was built.

The most important finding is that in elastic (e.g. polymer) materials part of relative motion occurs due to shear deformation of material – i. e. without sliding:

   

Wear rates of the tested materials evaluated in oscillatory motion were completely different from those in unidirectional sliding.

 

Results were used to select materials for greaseless guide vanes in a big Polish retrofitted power plant.

Direct contact: Dr Rafał Gawarkiewicz: gawar@pg.edu.pl

 

EXAMPLE 3:  WATER LUBRICATED THRUST BEARINGS

  • This is the most demanding application - required specific load 2-2.5 MPa, sliding speed up to 30-40 m/s
  • No applications known to us – very limited published research (only one paper on a relatively big thrust bearing experimental research – Inoue 2012)

On the other hand:

  • Water offers environmental safety and also a significant decrease in power losses (according to calculations by the factor of 4-5)
  • We believe we have knowledge, both in theoretical research and experiments and experience in water lubricated bearings applications
  • hydrodynamic thrust bearing test stand (SON) is available (but requires some adaptation to water lubrication conditions)

LET’S DO THIS RESEARCH TOGETHER

Direct contact: Dr Michał Wodtke: mwodtke@pg.edu.pl , Prof. Michał Wasilczuk: mwasilcz@pg.edu.pl