Research Papers

Experimental Study on Pressure Losses in Circular Orifices for the Application in Internal Cooling Systems

[+] Author and Article Information
Christian Binder

Siemens Industrial Turbomachinery AB,
Finspång 61231, Sweden
e-mail: christian.binder@mail.org

Mats Kinell

Siemens Industrial Turbomachinery AB,
Finspång 61231, Sweden
e-mail: mats.kinell@siemens.com

Esa Utriainen

Siemens Industrial Turbomachinery AB,
Finspång 61231, Sweden
e-mail: esa.utriainen@siemens.com

Daniel Eriksson

Siemens Industrial Turbomachinery AB,
Finspång 61231, Sweden
e-mail: daniel.eriksson@siemens.com

Mehdi Bahador

Siemens Industrial Turbomachinery AB,
Finspång 61231, Sweden
e-mail: mehdi.bahador@siemens.com

Johannes Kneer

Institut für Thermische Strömungsmaschinen,
Karlsruher Institut für Technologie,
Karlsruhe 76131, Germany
e-mail: johannes.kneer@kit.edu

Hans-Jörg Bauer

Institut für Thermische Strömungsmaschinen,
Karlsruher Institut für Technologie,
Karlsruhe 76131, Germany
e-mail: hans-joerg.bauer@kit.edu

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received July 24, 2014; final manuscript received August 13, 2014; published online September 30, 2014. Editor: Ronald Bunker.

J. Turbomach 137(3), 031005 (Sep 30, 2014) (10 pages) Paper No: TURBO-14-1171; doi: 10.1115/1.4028347 History: Received July 24, 2014; Revised August 13, 2014

The cooling air flow in a gas turbine is governed by the flow through its internal passages and controlled by restrictors such as circular orifices. If the cooling air flow is incorrectly controlled, the durability and mechanical integrity of the whole turbine may be affected. Consequently, a good understanding of the orifices in the internal passages is important. This study presents experimental results for a range of pressure ratios and length-to-diameter ratios common in gas turbines including even very small pressure ratios. Additionally, the chamfer depth at the inlet was also varied. The results of the chamfer depth variation confirmed its beneficial influence on decreasing pressure losses. Moreover, important effects were noted when varying more than one parameter at a time. Besides earlier mentioned hysteresis at the threshold of choking, new phenomena were observed, e.g., a rise of the discharge coefficient for certain pressure and length-to-diameter ratios. A correlation for the discharge coefficient was attained based on the new experimental data with a generally lower error than previous studies.

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Fig. 1

Orifice with the specifications measured and varied in the present study

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Fig. 2

Schematic diagram of the test rig

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Fig. 3

General characteristics of the discharge coefficient Cd

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Fig. 4

Effect of varying both p1/p2 and L/D

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Fig. 5

Effect of varying both L/D and W/D (a) and effect of varying both p1/p2 and W/D (b)

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Fig. 6

Effect of varying both p1/p2 and W/D at low p1/p2 for L/D=0.4 (a) and L/D=2.14 (b)

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Fig. 7

Effect of the bubble for varying L/D (a) and for varying W/D (b)

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Fig. 8

Onset of choking for varying L/D (a) and for varying W/D (b)

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Fig. 9

Hysteresis at the threshold of choking

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Fig. 10

Hysteresis at low pressure ratios p1/p2

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Fig. 11

Comparison of the measurements and the data from Hay and Spencer [7], Brain and Reid [4], and Deckker and Chang [3]

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Fig. 12

Comparison of the data and the correlation from Hüning [14]

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Fig. 13

Comparison of the new correlation and the measurements




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