Research Papers

Flow Measurements in a First Stage Nozzle Cascade Having Endwall Contouring, Leakage, and Assembly Features

[+] Author and Article Information
T. W. Simon

e-mail: tsimon@me.umn.edu
Heat Transfer Laboratory
Mechanical Engineering Department
University of Minnesota
Minneapolis, MN 55455

The slashface (or mid-passage) gap is a gap at the junction between two vane castings on the endwall. It can be seen in Fig. 1.

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received September 10, 2007; final manuscript received August 30, 2011; published online October 18, 2012. Editor: David Wisler.

J. Turbomach 135(1), 011002 (Oct 18, 2012) (11 pages) Paper No: TURBO-07-1131; doi: 10.1115/1.4006419 History: Received September 10, 2007; Revised August 30, 2011

This work supports new gas turbine designs for improved performance by evaluating the use of endwall contouring in a cascade that is representative of a first stage stator passage. Contouring accelerates the flow, reducing the thickness of the endwall inlet boundary layer to the turbine stage and reducing the strength of secondary flows within the passage. The reduction in secondary flows leads to less mixing in the endwall region. This allows for an improved cooling of the endwall and airfoil surfaces with injected and leakage flows. The present paper documents the component misalignment and injected and leakage flow effects on the aerodynamic losses within a passage that has one contoured and one straight endwall. Steps and injected flows within the passage can lead to thicker endwall boundary layers, stronger secondary flows, and possibly additional vortex structures in the passage. The paper compares losses with various steps, gaps, and leakage flows to assess their importance in this contoured passage. In particular, features associated with the combustor-to-turbine transition piece and the slashface on the vane platform are addressed. An n-factorial study is used to quantify the importance of such effects on aerodynamic losses.

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Fig. 2

Transition section step and gap geometry

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Fig. 3

Slashface step and gap geometry

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Fig. 4

Vane static pressure profile

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Fig. 5

Velocity (m/s), turbulence intensity, and velocity rms values at plane x/Cax = −1.5

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Fig. 6

Velocity (m/s), turbulence intensity, and velocity rms values at plane x/Cax= − 0.1

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Fig. 7

Pressure loss (ΔP) profile for the smooth passage

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Fig. 8

Endwall curvature of selected studies

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Fig. 9

Pressure loss profile (ΔP0) for the nominal passage

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Fig. 10

Pressure loss (ΔP0) profile for case 4, Table 7

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Fig. 11

Slashface blowing static pressure, velocity ratio, and momentum flux ratio




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