Volume 9, Issue 4 (April 2012)

    Bearing Thermal Conductance Measurement Test Method and Experimental Design

    (Received 25 July 2011; accepted 10 January 2012)

    Published Online: 2012

    CODEN: JAIOAD

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    Abstract

    Bearings are used in a number of spacecraft applications, ranging from minimal motion devices, such as pointing mechanisms, to high-speed components, such as control moment gyroscopes and reaction and momentum wheels. Terrestrial applications include pumps, axles, and tooling. Heat-transfer modes for rotational systems in a vacuum environment differ from their terrestrial counterpart. In space, with the absence of air, heat transfer consists of radiation from the rotating system and conductance through the bearings themselves. Depending on the application, conductance could dominate the effects on bearing temperatures and thermal gradients. Accurate thermal predictions are important because they can drive life and performance requirements. To accurately predict bearing temperatures, basic bearing thermal conductance data was needed. However, bearing thermal conductance tends to be the most significant unknown in a rotational system in the space environment. To address this shortcoming, this paper explores a new vacuum test rig designed to measure bearing conductance under simulated operational conditions. Experimental variables include control of the bearing rotational speed, applied axial load, and average bearing temperature and temperature gradient via an applied heat source/heat sink mechanism. All tests are conducted in vacuum. The experimental variables studied herein allowed parametric studies to be conducted under controlled thermal and mechanical conditions, permitting the exploration of the influences of those operational variables on bearing thermal conductance. This paper will describe the test method, the use of uncertainty analysis to design the experiment, and a verification study.


    Author Information:

    Takeuchi, Yoshimi R.
    Engineering and Technology Group, The Aerospace Corporation, El Segundo, CA

    Davis, Sean E.
    Engineering and Technology Group, The Aerospace Corporation, El Segundo, CA

    Eby, Matthew A.
    Engineering and Technology Group, The Aerospace Corporation, El Segundo, CA

    Fuller, Jerry K.
    Engineering and Technology Group, The Aerospace Corporation, El Segundo, CA

    , Donald L.

    Rosado, Michael J.
    Engineering and Technology Group, The Aerospace Corporation, El Segundo, CA


    Stock #: JAI104233

    ISSN: 1546-962X

    DOI: 10.1520/JAI104233

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    Author
    Title Bearing Thermal Conductance Measurement Test Method and Experimental Design
    Symposium , 0000-00-00
    Committee F27