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Research Papers: Gas Turbines: Structures and Dynamics

# Experimental Analysis of Air∕Oil Separator Performance

[+] Author and Article Information
K. Willenborg

Air and Oil Systems,  Rolls-Royce Deutschland Ltd & Co. KG, Eschenweg 11, Dahlewitz 15827 Blankenfelde Mahlow, Germanyklaus.willenborg@rolls-royce.com

M. Klingsporn

Air and Oil Systems,  Rolls-Royce Deutschland Ltd & Co. KG, Eschenweg 11, Dahlewitz 15827 Blankenfelde Mahlow, Germany

S. Tebby, T. Ratcliffe

Dunlop Equipment Ltd., Holbrook Lane, Coventry, CV6 4QY, UK

P. Gorse, K. Dullenkopf, S. Wittig

Institut für Thermische Strömungsmaschinen,  Universität Karlsruhe, Kaiserstrasse 12, 76128 Karlsruhe, Germany

J. Eng. Gas Turbines Power 130(6), 062503 (Aug 28, 2008) (10 pages) doi:10.1115/1.2795785 History: Received November 07, 2006; Revised July 22, 2007; Published August 28, 2008

## Abstract

Within the European research project (Advanced Transmission and Oil System Concepts), a systematic study of the separation efficiency of a typical aeroengine air∕oil separator design was conducted. The main objectives were to obtain a basic understanding of the main separation mechanisms and to identify the relevant parameters affecting the separation efficiency. The results of the study contribute to an optimized separator technology. Nonintrusive optical measurement techniques like laser diffraction and multiple wavelength extinction were applied to analyze the separation efficiency and identify potential optimization parameters. Oil mist with defined oil droplet size distribution was supplied to the breather. By simultaneously measuring particle size and oil concentration upstream and downstream of the breather, the separation mechanism was analyzed and the separation efficiency was assessed. In addition, the pressure drop across the separator was measured. The pressure drop is an important design feature and has to be minimized for proper sealing of the engine bearing chambers. The experimental programe covered a variation of air flow, oil flow, shaft speed, and droplet size. The main emphasis of the investigations was on the separation of small droplets with a diameter of up to $10μm$. The following trends on separation efficiency of small droplets were observed: The separation efficiency increases with increasing rotational speed, with increasing particle size, and with decreasing air flow rate. In parallel, the pressure drop across the breather increases with increasing speed and increasing air flow.

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## Figures

Figure 1

Typical breather design

Figure 2

Structure of Dunlop Retimet® metal foam, Grade 45

Figure 3

Flow map for vent pipe flow, vertical upward

Figure 4

Two-phase flow patterns for vertical upward flow

Figure 5

Schematic of Dunlop breather test rig

Figure 6

Schematic of droplet generator design

Figure 7

Droplet size distribution

Figure 8

Effect of air flow rate on separation of small droplets, n∕nIdle=1.0, Voil,inlet=0.2l∕h

Figure 9

Effect of separator speed on separation of small droplets, Voil,inlet=0.2l∕h, Wair∕Wair,Idle=1.0

Figure 11

Effect of air flow rate on breather pressure drop, n∕nIdle=1.0, Voil,inlet=2.0l∕h

Figure 12

Effect of rotational speed on breather pressure drop, Wair∕Wair,Idle=1.0, Voil,inlet=2.0l∕h

Figure 10

Effect of droplet size on separation efficiency, Wair∕Wair,Idle=1.0, n∕nIdle=0.5, Voil,inlet=1.8–5.6l∕h

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