Measurements to Quantify the Effect of a Reduced Flow Rate on the Performance of a Tilting Pad Journal Bearing (LBP) With Flooded Ends Conference Paper uri icon

abstract

  • Abstract Operation of tilting pad journal bearings (TPJBs) with a reduced flow decreases pumping costs and oil sump storage. A low supplied oil flow improves system energy efficiency by reducing drag power losses, albeit the temperature rise in both the bearing pads and the lubricating oil become a concern. This paper presents measurements of the static and dynamic load performance of a flooded ends TPJB lubricated with an ISO VG 46 oil supplied at 60 C, and with flowrate ranging from 150% to just 5% of a nominal supply condition. The flow range covers both over-flooded and starved flow conditions. The test bearing is a four-pad, 102 mm diameter, center pivot, with single orifice feeds, and configured with end seals to flood the bearing housing. The experiments include operation at two shaft speeds = 6 krpm and 12 krpm (= 64 m/s surface speed) and under three specific loads = 0.345 MPa, 1.03 MPa and 2.07 MPa applied in between pads (LBP). The measurements show the bearing drag power loss decreases by nearly 20% when the flow rate drops to 50% of nominal. However, halving the flow produces a raise in pad subsurface temperatures, 7 C for operation at 12 krpm. Flow reduction below 50% does result in even more substantial power savings; however, it also produces too hot pad temperatures that approach 130 C, a known limit for Babbitt material safe operation. The bearing static eccentricity (e) and direct stiffnesses Kxx > Kyy (load direction) do not show a significant dependency on the supplied flow, either above or below the nominal condition. A minor stiffness hardening does occur for very low flow conditions, 5% or so of nominal. Damping coefficients (Cxx Cyy) decrease by 30% as the flow rate decreases from 150% to just a few % of nominal flow. The experimental results are first to quantify operation of a TPJB supplied with minute amounts of lubricant flow. A test with a very low flow rate at 2% of nominal and under a light load produced the emergence of a broadband subsynchronous vibration frequency, albeit with very small amplitude.

name of conference

  • Volume 9A: Structures and Dynamics Aerodynamics Excitation and Damping; Bearing and Seal Dynamics; Emerging Methods in Design and Engineering

published proceedings

  • Volume 9A: Structures and Dynamics Aerodynamics Excitation and Damping; Bearing and Seal Dynamics; Emerging Methods in Design and Engineering
  • Volume 9A: Structures and Dynamics — Aerodynamics Excitation and Damping; Bearing and Seal Dynamics; Emerging Methods in Design and Engineering

author list (cited authors)

  • San Andrs, L., Toner, J., & Alcantar, A.

citation count

  • 1

complete list of authors

  • San Andrés, Luis||Toner, Jonathan||Alcantar, Andy

publication date

  • June 2021