Experimental Characterization of Large Turbomachinery Tilting Pad Journal Bearings

Enrico Ciulli,Matteo Nuti,Paola Forte,Riccardo Ferraro,Alice Innocenti

doi:10.3390/machines9110273

Abstract

The paper deals with the experimental characterization of different 280 mm diameter tilting pad journal bearings for turbomachines using a dedicated test rig. The test articles were a 5-pad Direct Lube Rocker Pivot bearing, a 5-pad Flooded Rocker Pivot bearing, and a 4-pad Flooded Ball and Socket Pivot bearing. The three bearings were tested in their specific design range of operating conditions. Their static and dynamic behavior was investigated as a function of different operating parameters. In particular, the assumed journal center eccentricity and pads temperature were measured, and the power loss determined as a function of angular speed for different static loads. Dynamic stiffness and damping coefficients were determined as a function of excitation frequency for different speeds and loads. The experimental results were compared showing the influence of the operating parameters, configuration, and oil supply.

Highlights

Tilting pad journal bearings (TPJB) are essential components for supporting the rotors of turbomachinery industrial applications, guaranteeing stability and efficiency even in increasingly severe operating conditions in terms of load and speed.TPJBs have been the subject of extensive theoretical and experimental studies in recent decades focusing in particular on their dynamic characteristics
After a brief description of the experimental apparatus and of the procedures used, this paper presents and discusses the experimental results obtained with different 280 mm diameter TPJBs
The contribution of direct damping and cross-coupling stiffness behavior at high speeds lead to a higher stability behavior of the Flooded Ball & Socket Pivot bearing with respect to the Direct Lube Rocker Pivot one

Summary

Introduction

Tilting pad journal bearings (TPJB) are essential components for supporting the rotors of turbomachinery industrial applications, guaranteeing stability and efficiency even in increasingly severe operating conditions in terms of load and speed. A 580 mm diameter direct lubrication TPJB for steam turbine was studied experimentally statically and dynamically using a full-scale bearing test rig and compared to a conventional flooded lubrication bearing, investigating the vibration of pads [5]. In the last few years, experimental campaigns for the preliminary validation of different types of tilting pad journal bearings in terms of both dynamic and static performance have been carried out on TPJBs with diameter larger than 250 mm in the test rig developed thanks to the joint effort of the University of Pisa and the companies Baker Hughes and AM Testing [20,21,22]. The test results, unique in the considered size range, will show the influence of load, speed, type of oil supply, pad configuration and some particular effects such as turbulence. Not all the geometrical features will be disclosed, being confidential information of Baker Hughes, the paper can be of interest to researchers in the field of centrifugal compressors and industrial steam turbines since the investigated experimental conditions are representative of more severe operating conditions with respect to the standard ones

The Experimental Apparatus

Dynamic Coefficients Identification Method

Tested Bearings

The Pad Temperatures

Findings

Discussion and Conclusions