Due to the increasing demands of taking care of the environment there is a continual search for new ways to accomplish environmental improvements. Even if hydropower is one of the most clean energy sources, there are possibilities to make improvements even here.
One example of such improvements is to try to get rid of the oil which is used as a lubricant in the runnerhubs of kaplanturbines. In order to accomplish this, new ways to mount in the moving parts, has to be invented. The progress in materials research has made it interesting to investigate if it is possible to use some kind of self-lubricating bearing material. The present work makes a careful study on this exact problem.
The investigation contents contacts with experts in this area, contacts with manufacturers of self-lubricating materials and an extensive literature study of research reports and their progress. The work makes no intention to include the hole amount of information on this field, but intends to give an overlook of which possibilities there are and what has to be done in the future.
The dimensioning criteria of bearings in this type of stress is wear. The wear is very sensitive to the actual conditions under which they operate. It is very hard to use theoretical models to estimate the wear with enough accurency.
It is also so if you want to make conclusions from experimental investigations, the tests has to be very similar to the true application. This means that there are big demands on knowing the stresses of the real application. So far no tests that are done is god enough. The demands on the bearing for the runnerhub has not been very clear either.
The work has not given a strict answer if there are any materials that satisfy the demands. It should be mentioned that it has not been possible to prove the opposite either.
The results that this report has lead to is a strategy for how to reach the wished goals. Important parameters has been given and number of testing methods has been evaluated. It has also, with the experimental investigations that has been done, been possible to name a number of materials that seems to be interesting for further investigation.
It is proposed to do a careful investigation of the function of the kaplan runner hub. A study of the total amount of hydropowerplants that are exposed for the high demands are needed. It is also proposed to do a careful experimental investigation of bearing materials under correct stresses, and with this try to create accurate theories that can be used for similar problems in the future.