STP1542: Steel and Hybrid Spacecraft Ball-Bearing Thermal Conductance Comparisons

    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

    Pages: 25    Published: Oct 2012


    Abstract

    In vacuum, bearing temperatures are primarily governed by two properties: bearing thermal conductance, which governs the overall heat transfer through the bearing, and heat generation, which is caused by the frictional mechanical losses during bearing motion. Both quantities need to be known for accurate bearing thermal predictions in a vacuum environment. The heat generation term, which is related to torque multiplied by rotational speed, is the better known of the two quantities. Information on bearing thermal conductance; on the other hand, tends to be more poorly quantified, and thus will be the focus of this paper. A comparison will be made between the thermal conductance of all-steel and hybrid bearings containing silicon nitride ceramic balls inside steel races. Thermal conductance is a function of various operational conditions, such as rotational speed, temperature, mechanical loading and presence of lubricant. The exact effects the aforementioned variables have on bearing thermal conductance will be explored in more detail for both bearing types. Results indicate that, for a given bearing size and geometry, bearing thermal conductance is most strongly influenced by the presence and amount of liquid lubricant and state of motion. Both all-steel and hybrid bearings react to these variables in a comparable manner.

    Keywords:

    bearing thermal conductance, thermal resistance, experiment, hybrid bearings, steel bearings


    Paper ID: STP104234

    Committee/Subcommittee: F34.01

    DOI: 10.1520/STP104234


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