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Research Papers: Gas Turbines: Aircraft Engine

Improving the Performance of a Bent Ejector With Inlet Swirl

[+] Author and Article Information
Asim Maqsood

Department of Mechanical and Materials Engineering, Queen’s University, Kingston, ON, K7L3N6, Canada1am21@queensu.ca

A. M. Birk

Department of Mechanical and Materials Engineering, Queen’s University, Kingston, ON, K7L3N6, Canadabirk@me.queensu.ca

J. Eng. Gas Turbines Power 130(6), 061201 (Aug 22, 2008) (9 pages) doi:10.1115/1.2943196 History: Received March 26, 2008; Revised April 25, 2008; Published August 22, 2008

Ejectors are commonly employed in gas turbine exhaust systems for reasons such as space ventilation and IR suppression. Ejectors may incorporate bends in the geometry for various reasons. Studies have shown that the bend has a deteriorating effect on the performance of an ejector. This work was aimed to investigate the effect of exhaust gas swirl on improving the performance of a bent ejector. Four short oblong ejectors with different degrees of bend in the mixing tube and four swirl conditions were tested in this study. The primary nozzle, in all cases, was composed of a circular to oblong transition. Testing was performed at ambient and hot primary flow with 0deg, 10deg, 20deg, and 30deg swirl angles. It was observed that the swirl had a strong affect on the performance of a bent ejector. Improvement of up to 55%, 96%, and 180% was obtained in the pumping ratio, pressure rise, and total efficiency, respectively, with a 20deg swirl in the exhaust gas.

Copyright © 2008 by American Society of Mechanical Engineers
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Figures

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Figure 1

Schematic of the wind tunnel (all dimensions are in millimeters—length shortened to highlight small details)

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Figure 2

Schematic showing instrumentation and measurement planes on the ejector and wind tunnel

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Figure 3

Geometry detail of the test ejectors (all dimensions are in millimeters)

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Figure 4

Effect of the degree of bend in the mixing tube on the pumping ratio of the ejector; hot and cold flow testings presented without any swirl in the primary flow (16)

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Figure 5

Effect of swirl on the pumping ratio of ejectors having mixing tubes bent at various angles—cold primary flow presented (T*=1)

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Figure 6

The effect of swirl in the primary flow on the pumping ratio of ejectors having mixing tubes bent at various angles—hot primary flow presented (T*=0.4)

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Figure 7

The effect of bend angle of the mixing tube of the ejector on the pressure rise—no swirl in the primary flow (16)

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Figure 8

The effect of swirl in the primary flow on the pressure rise of the bent ejectors

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Figure 9

The effect of swirl on the kinetic energy flux factor of the 35deg bent ejector

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Figure 10

The effect of swirl in the primary flow on the kinetic energy flux factor of the 67.5deg bent ejector

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Figure 11

The effect of swirl in the primary flow on the efficiency of the bent ejectors—cold primary flow (T*=1)

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Figure 12

The effect of swirl in the primary flow on the efficiency of the bent ejectors—hot primary flow (T*=0.4)

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Figure 13

Axial velocity profile at the horizontal centerline of the exit cross section of the straight ejector—the effect of different temperatures and swirls in the primary flow

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Figure 14

Axial velocity profile at the horizontal centerline of the exit cross section of the 35deg bent ejector—effect of swirl on the spreading of momentum

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Figure 15

Axial velocity profile at the horizontal centerline of the exit cross section of the 67.5deg bent ejector—effect of swirl on the spreading of momentum

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Figure 16

Contours of axial velocity (w), overlaid by cross-stream velocity at the exit of the nozzle measured by a seven-hole probe in the hot flow mass conservation tests with (a) 0deg swirl and (b) 30deg swirl in the primary flow

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Figure 17

Axial velocity contour plots at the exit of the straight, 35deg and 67.5deg bent ejectors, overlaid by vectors of cross-stream flow at different swirl conditions—measured by traversing a seven-hole probe at the exit sections of the ejectors

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