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Research Papers

Hybrid LES Approach for Practical Turbomachinery Flows—Part II: Further Applications

[+] Author and Article Information
Paul Tucker1

Department of Engineering, Whittle Laboratory, University of Cambridge, Cambridge CB3 0DY, United Kingdom

Simon Eastwood, Christian Klostermeier, Hao Xia, Prasun Ray, James Tyacke, William Dawes

Department of Engineering, Whittle Laboratory, University of Cambridge, Cambridge CB3 0DY, United Kingdom

1

Corresponding author.

J. Turbomach 134(2), 021024 (Jul 07, 2011) (10 pages) doi:10.1115/1.4003062 History: Received July 02, 2010; Revised July 30, 2010; Published July 07, 2011; Online July 07, 2011

A hybrid large eddy simulation (LES) related technique is used to explore some key turbomachinery relevant flows. Near wall Reynolds-averaged Navier-Stokes (RANS) modeling is used to cover over especially small scales, the LES resolution of which is generally intractable with current computational power. Away from walls, large eddy type simulation is used but with no LES model (numerical LES (NLES)). Linking of the two model zones through a Hamilton–Jacobi equation is explored. The hybrid strategy is used to predict turbine and compressor end wall flows, flow around a fan blade section, jet flows, and a cutback trailing edge. Also, application of NLES to the flow in an idealized high pressure compressor drum cavity is considered. Generally, encouraging results are found. However, challenges remain, especially for flows where transition modeling is important.

Copyright © 2012 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

λ2 contours for the compressor blade

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Figure 2

Spanwise variation in pitchwise mass-averaged exit flow angle (dashed line, NLES; full line, NLES-RANS; О, measurements (22))

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Figure 3

Spanwise variation in pitchwise mass-averaged loss coefficient (dashed line, NLES; full line, NLES-RANS; О, measurements (22))

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Figure 4

Streamlines on the compressor end wall: (a) flow visualization of Ref. 22, (b) NLES contours, and (c) NLES-RANS contours

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Figure 5

Passage-averaged total pressure loss coefficient against axial chord (dashed line, NLES; solid line, NLES-RANS; Δ, measurements (23))

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Figure 6

Spanwise variation in pitchwise total pressure loss coefficient (dashed line, NLES; solid line, NLES-RANS; О, measurements (24))

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Figure 7

Streamlines on the turbine end wall: (a) flow visualization (23), (b) NLES contours, and (c) NLES-RANS contours

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Figure 8

Geometry and mesh for the coaxial nozzle. (a) Jet nozzle geometry and (b) near nozzle mesh.

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Figure 9

Hybrid RANS-NLES predicted profiles and contours of velocity and Reynolds stresses for coflowing jet: (a) streamwise velocity, (b) normal stress, and (c) shear stress (solid line, NLES-RANS; ◻, measurements (27))

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Figure 10

Predicted instantaneous flow field for Re=300,000 coaxial nozzle: (a) vorticity contours and (b) vorticity isosurfaces

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Figure 11

Hybrid NLES-RANS of a coflowing jet with real geometry features: (a) multiblock grid sections for nozzle with pylon, (b) total pressure isosurfaces for nozzle with internal geometry, (c) contours of time-averaged axial velocity at different axial planes for nozzle with internal geometry, and (d) instantaneous vorticity contours for pylon flow

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Figure 12

Turbulent kinetic energy profiles at different axial locations (……., normal nozzle; ______, nozzle with pylon)

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Figure 13

Geometry and mesh for the chevron nozzle. (a) Nozzle geometry and (b) near nozzle mesh

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Figure 14

Hybrid RANS-NLES predicted profiles of streamwise velocity on: (a) chevron tip and (b) chevron root (solid line, NLES-RANS; ◻, measurements (30))

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Figure 15

Hybrid RANS-NLES predicted profiles of normal stress on (a) chevron tip and (b) chevron root (solid line, NLES-RANS; ◻, measurements (30))

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Figure 16

Density gradient contours on (a) chevron tip and (b) chevron root

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Figure 17

Far-field PSD at (a) side line and (b) downstream locations

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Figure 18

Schematic of rotating cavity with an axial throughflow

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Figure 19

High speed pressure drum section

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Figure 20

Comparison of NLES predictions with smoke flow visualization for an idealized high pressure compressor drum cavity flow: (a) t=1 and (b) t=7 s

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Figure 21

Mesh structure and temperature field: (a) hexahedral based octree mesh and (b) instantaneous flow structure

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Figure 22

Flow structure at two instances for cutback trailing edge flow: (a) instantaneous streamlines and temperature contours and (b) instantaneous streamlines

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Figure 23

Contours of time-averaged M for hybrid RANS-NLES

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Figure 24

Instantaneous M=1 Mach number isosurface and isosurface of instantaneous vorticity magnitude

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Figure 25

Blade surface pressure spectra for different spanwise mode numbers, pressure-side, x/L∼0.8. _ _ _ _ m=0;_ _ _ m=1; _ . _ m=2, … m=3

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