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Research Papers: Fundamental Issues and Canonical Flows

Optimal Performance and Geometry of Supersonic Ejector

[+] Author and Article Information
N. I. Hewedy, F. Sh. Abou-Taleb

Mechanical Power Engineering Department, Faculty of Engineering, Menoufiya University, Egypt

Mofreh H. Hamed1

Mechanical Power Engineering Department, Faculty of Engineering, Menoufiya University, Egyptmofrehhh@yahoo.com

Tarek A. Ghonim

Mechanical Power Engineering Department, Faculty of Engineering, Menoufiya University, Egypttareḵghonim@yahoo.com

1

Presently at Kafrelsheikh University.

J. Fluids Eng 130(4), 041204 (Apr 16, 2008) (10 pages) doi:10.1115/1.2903742 History: Received December 31, 2006; Revised October 04, 2007; Published April 16, 2008

The optimum geometries of the ejectors, which give maximum efficiency, are numerically predicted and experimentally measured. The numerical investigation is based on flow equations governing turbulent, compressible, two-dimensional, steady, time averaged, and boundary layer equations. These equations are iteratively solved using finite-difference method under the conditions of different flow regimes, which can be divided into several distinctive regions where the methods for estimating the mixing length are different for each flow region. The first region depicts the wall boundary layer, jet shear layer, and secondary and primary potential flows. The second one contains a single region of developing flow. A simple ejector with convergent-divergent primary nozzle was fabricated and experimentally tested. The present theoretical and experimental results are well compared with published data. The results obtained are used to correlate the optimum ejector geometry, pressure ratio, and ejector optimum efficiency as functions of the operation parameters and ejector area ratio. The resultant correlations help us to select the optimum ejector geometry and its corresponding maximum efficiency for particular operating conditions.

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Copyright © 2008 by American Society of Mechanical Engineers
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Figures

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Figure 1

Ejector geometry, boundary conditions, and computational grid

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Figure 2

Experimental setup

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Figure 4

Comparison between predicted wall static pressure distributions and published theoretical and experimental data (3) for different entrainment ratios (PO1=24bars, TO1=706K)

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Figure 5

Comparison between predicted radial variation of axial velocity and published theoretical and experimental data (3) at four axial locations (PO1=24bars, TO1=706K, and μ=21)

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Figure 6

Comparison between predicted radial variation of stagnation temperature and published theoretical and experimental data (3) at four axial locations (PO1=24bars, TO1=706K, and μ=21)

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Figure 7

Comparison between predicted wall static pressure coefficient distributions and experimental data at different inflow conditions

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Figure 8

Effect of area ratio on static pressure coefficient distributions along the ejector geometry (μ=6, CpO=1.76, λ=1)

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Figure 9

Effect of area ratio on centerline Mach number distributions along the ejector geometry (μ=6, CpO=1.76, λ=1)

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Figure 10

Effect of area ratio on ejector efficiency and pressure ratio for different inflow conditions: (a) Effect of mass ratio (CpO=1.76, λ=1.0); (b) effect of temperature ratio (CpO=1.76, μ=5); (c) effect of stagnation pressure coefficient (μ=5, λ=1.0)

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Figure 11

Comparison between numerical prediction and values predicted by correlations 10,11,12,13,14

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Figure 12

Optimum characteristic curves for ejector performance at five different area ratios: (a) Ar=3.13; (b) Ar=4.17; (c) Ar=6.25; (d) Ar=10.42; (e) Ar=16.68

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Figure 13

Optimum characteristic curves for ejector performance at four different temperature ratios: (a) λ=1; (b) λ=2; (c) λ=3; (d) λ=4

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