Active Shape Control of the Lubricant Film Geometry in Adaptive Air Foil Bearings
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Beschreibung
The active adaptation of the geometric properties under consideration of different operating conditions
optimizes the overall performance of many systems. Shape control with intelligent materials is a wellknown
approach in various aerospace applications, especially where fluid-solid interactions occur. In this
study, shape morphing is considered as an efficient approach for air foil bearings with the ability to actively
adjust the lubricant profile by forming the bearing shells. With regard to the designing demands for oilfree
bearings, various solutions are widely discussed in the literature. While some of them are reported
to be insufficient for any particular criteria, others do not only improve performance for certain operating
conditions but also have a negative effect during other running states due to conflicting design goals. The
replacement of the circular bearing housing by a lobed housing generates a hydrodynamic preload effect
in the lubricating film. This approach is one of the most frequently investigated methods for improving
the bearing stability, which is followed by negative influences on the load capacity and thus an increased
lift-off speed. In addition, the uniform reduction or increase of the radial clearance of the bearings has its
own effects on the static and rotordynamic properties of the air foil bearings. Such observations lead to the
presentation of different solutions for active bearing contour adjustment, which benefit from different profiles
of the lubricant film. In all cases in which the geometric shape is to be actively adapted in each operating
state, particular attention must be paid to structural conformity, i.e. the harmonization of the stiffness of the
system in relation to the requirements for shape control. In line with this, the focus of this study is on the
development of an adaptive interface for air foil bearings in which the negative effects of introducing new
degrees of freedom into the system must be investigated prior to the actual application.
Autor*in
Hossein Sadri
Themen in »Active Shape Control of the Lubricant Film Geometry in Adaptive Air Foil Bearings«
Air Foil Bearings Folienlager Formvariabilität Luftlager Piezoelektrische Aktorik Shape-morphing