Numerous experimental studies have already established the fact that surface texturing can successfully improve the hydrodynamic performances of lubricated contacts. In a 2005 review paper, Etsion [1] offered a synthesis of these works and showed that surface texturing can benefit a large variety of tribological applications such as mechanical seals, thrust bearings or piston rings. However, the physical interpretation of the effects induced by textures still represents a subject of debate within the tribological community. The earliest investigation with regard to surface textures dates back to the 1960’s and is attributed to Hamilton et al. [2]. The authors reported that the cavitation phenomenon induced by small irregularities is essential, as it allows high film pressures to overbalance low film pressures due to an antisymmetric pressure distribution.

This is Part I of a two-part series of papers describing the effects of high pressure injection pockets on the operating conditions of tilting-pad thrust bearings. A numerical model based on the Reynolds equation is developed extending the three dimensional thermo-elasto-hydrodynamic (TEHD) analysis of tilting-pad thrust bearings to include the effects of high pressure injection and recesses in the bearing pad. The model is applied to the analysis of an existing bearing of large dimensions and the influence of the pocket is analyzed. It is shown that a shallow pocket positively influences the performance of the bearing as it has characteristics similar to those of a parallel step bearing.

This is Part II of a two-part series of papers describing the effects of high pressure injection pockets on the operating conditions of tilting-pad thrust bearings. Measurements of the distribution of pressure and oil film thickness are presented for tilting-pad thrust bearing pads of approximately 100 cm 2 surface area. Two pads are measured in a laboratory test-rig at loads of approximately 0.5, 1.5 and 4.0 MPa and velocities of up to 33 m/s. One pad has a plain surface. The other pad has a conical injection pocket at the pivot point and a leading edge taper. The measurements are compared to theoretical values obtained using a three dimensional thermoelasto-hydrodynamic (TEHD) numerical model. At low and intermediate loads the theoretical pressure distribution corresponds well to the measured values for both pads although the influence of the pocket is slightly underestimated. At high loads large discrepancies exist for the pad with an injection pocket. It is argued that this is likely to be due to the unevenness of the collar surface. The measured and theoretical values of oil film thickness compare well at low loads. At high loads discrepancies grow to up to 25 %. It is argued that this is due to the accuracy of the measurements.

A single pad thrust bearing with central orifice restrictor, was fabricated and tested with a loading frame design for varying loads and supply pressures. One of the objectives of conducting the test was to obtain load verses air-gap curves for different supply pressures. The air bearing was supplied with different diameters of orifice. Another objective was to measure recess pressure at different supply pressures and loads and obtain a three dimensional plot. The recess pressure in the bearing is measured by the Smart Pressure Device. The testing of the thrust bearing enabled to validate the measurement system used. The results obtained were in good agreement with the investigations made in this field by other investigators. The sensor used also showed good repeatability and linearity, which approves its use for the measurement system.