Analysis of diamond segmented pads on rotating and stationary bearings in contact sliding

Polycrystalline diamond (PCD) bearings are designed for severe conditions where contaminated fluids, high and varying loads and speeds, and elevated temperatures cause failure in machine components. PCD bearings have demonstrated successful application in the oil and gas industry, marine environments, and many others due to their unique properties: hardest known material, high thermal conductivity, superior wear resistance, and low coefficient of friction (COF). This paper discusses the development and results of a thermal computational fluid dynamic (CFD) analysis for PCD bearings with comparison to laboratory test results. The analysis was performed on a single pad segment of the PCD bearing. With specified fluid properties, flow rate, speed, load, and COF, the analysis determines the heat transfer coefficient in terms of the dimensionless Nusselt (Nu) number. The Nu number was developed through the use of five dimensionless governing parameters: the Reynolds (Re) number, the Prandtl (Pr) number, a viscous heat dissipation term, a thermal conductivity term, and a total mass flow rate term. The results show consistency between the CFD analysis and the laboratory tests with a generalized heat transfer coefficient ranging from 500 to 3000 W/m2K, depending upon the input parameters. This analysis will further the design and development of segmented PCD bearings.

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