Ligament and Droplet Generation by Oil Film on a Rotating Disk

Hengchao Sun,Guoding Chen,Fei Wang,Li’na Wang

doi:10.1155/2015/769862

Hengchao Sun, Guoding Chen + Show 2 more

Open Access

https://doi.org/10.1155/2015/769862

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Abstract

The lubrication and heat transfer designs of bearing chamber depend on an understanding of oil/air two-phase flow. As initial and boundary conditions, the characteristics of ligament and droplet generation by oil film on rotating parts have significant influence on the feasibility of oil/air two-phase flow analysis. An integrated model to predict the oil film flow, ligament number, and droplet Sauter mean diameter (SMD) of a rotating disk, which is an abstraction of the droplet generation sources in a bearing chamber, is developed based on the oil film force balance analysis and wave theory. The oil film thickness and velocity, ligaments number, and droplet SMD are calculated as functions of the rotating disk radius, rotational speed and oil volume flow rate and oil properties. The theoretical results show that the oil film thickness and SMD are decreased with an increasing rotational speed, while the radial, transverse velocities, and ligament number are increased. The oil film thickness, radial velocity, and SMD are increased with an increasing oil flow rate, but the transverse velocity and ligament number are decreased. A test facility is built for the investigation into the ligament number of a rotating disk, and the measurement of ligament number is carried out by means of a high speed photography.

Highlights

Bearing chamber is an important component of aeroengine and it gives a guarantee of shaft running reliably
Several researchers have conducted the theoretical and experimental investigations onto the oil/air two-phase flow in bearing chamber. Their works focused on the characteristic of oil droplets which are atomized by rotating parts [1,2,3,4,5,6,7], oil droplet motion, and deposition on chamber housing [8,9,10], as well as oil film flow with chamber housing [11,12,13,14]
For the sake of convenience, the extremely complicated and detailed design which is found in actual engine bearing chamber is omitted in the present paper and the flow regime of oil on underrace lubrication collector, bearing, and seal rotor is treated as the oil flowing on a rotating flat disk based on a reasonable simplification

Summary

Introduction

Bearing chamber is an important component of aeroengine and it gives a guarantee of shaft running reliably. Several researchers have conducted the theoretical and experimental investigations onto the oil/air two-phase flow in bearing chamber. Their works focused on the characteristic of oil droplets which are atomized by rotating parts [1,2,3,4,5,6,7], oil droplet motion, and deposition on chamber housing [8,9,10], as well as oil film flow with chamber housing [11,12,13,14]. Glahn et al [1] carried out experimental investigation on size and velocity of droplet which was atomized by bearing. The work may be helpful to improve the research system of oil/air two-phase flow in the bearing chamber

An Abstraction of the Droplet Generation Sources in a Bearing Chamber

Theoretical Model Development

Oil Film Velocity and Thickness on a Rotating Disk

Results and Discussion

Experimental Study

Conclusions