David Macmillan

Research degree: PhD programme
Start date: 2021

Project

Reduction of Energy Loss in Tilting-Pad Thrust Bearings by Active Control

Tilting-Pad Thrust Bearings are a tribological machine element widely used throughout industry in applications ranging from turbomachinery to vessel propulsion systems. They utilise a self-pressurised thin film of lubricant to separate surfaces in relative motion, providing a low friction contact and high-load capability.

Conventionally, Tilting-Pad Thrust Bearings operate as a passive device requiring no external control to function. The disadvantage of the passive bearing is the inability to monitor and adapt to changes in operating conditions leading to improved performance, reliability, and efficiency.

Implementation of a tribotronic system provides real-time active control with the objective to address some of the notable deficiencies. Such a system is realised by combining the mechanical function with sensors, controllers, and actuators to regulate features of design such as geometry and lubrication.

Research into tribotronic or active Tilting-Pad Thrust Bearings has received limited attention compared to the journal bearing counterpart. Moreover, these active solutions have mainly concentrated on mitigating dynamic instability in rotor-bearing systems. However, reducing friction losses in tribological elements is gaining precedence because of the effect on global energy consumption and environmental impacts.

As a result, the current project aims to integrate a tribotronic system within the Tilting-Pad Thrust Bearing to mitigate viscous shearing losses and heat generation within the contact. The initial stage of the project has been to develop a Finite-Element model of a single tilting pad to determine the effectiveness of controlling the oil film geometry during operation.

Theoretical results have shown that the variation in pad tilt provides effective means to optimise performance characteristics such as friction losses and load carrying capacity. Based on the current results, an active geometric control system has been proposed. Further work will be to develop the tribotronic bearing and carry out experimental tests.

The experimental results will be used to validate the model and compare performance between the conventional bearing and the tribotronic bearing.

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Research Supervisor: Professor Ian Sherrington
Student: David Macmillan