High-speed foil bearings for micro gas turbines: test set-up

Mesoscopic or microscopic gas turbines are popular research topics as they could replace batteries. However, a drawback of the miniaturization is the increased rotational speed which should be in the order of 500.000 rpm. Air bearings and more in particular foil bearings are very interesting for application in these units. In this paper we discuss a test set-up to validate our numerical models for foil bearings. This set-up makes it possible to measure the load characteristics of a bearing in a very accurate way since it is based on a 3-bearing configuration. It is known from literature that the clearance value C has a very large influence on the bearing behaviour. Therefore a system to vary the clearance value is proposed. Performing experiments with small clearance variations also allows estimating the initial clearance: an interesting feature as the initial clearance C for flexible geometry bearing, e.g. foil bearings, is hard to measure with sufficient accuracy.