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Research Papers

Modular Turbulence Modeling Applied to an Engine Intake

[+] Author and Article Information
Ugochukwu R. Oriji

e-mail: uro20@cam.ac.uk

Paul G. Tucker

e-mail: pgt23@cam.ac.uk
Department of Engineering,
University of Cambridge,
Cambridge CB2 1PZ, UK

Thesis to be submitted.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received May 29, 2013; final manuscript received August 10, 2013; published online September 27, 2013. Editor: Ronald Bunker.

J. Turbomach 136(5), 051004 (Sep 27, 2013) (10 pages) Paper No: TURBO-13-1086; doi: 10.1115/1.4025232 History: Received May 29, 2013; Revised August 10, 2013

The one equation Spalart–Allmaras (SA) turbulence model in an extended modular form is presented. It is employed for the prediction of crosswind flow around the lip of a 90 deg sector of an intake with and without surface roughness. The flow features around the lip are complex. There exists a region of high streamline curvature. For this, the Richardson number would suggest complete degeneration to laminar flow. Also, there are regions of high favorable pressure gradient (FPG) sufficient to laminarize a turbulent boundary layer (BL). This is all terminated by a shock and followed by a laminar separation. Under these severe conditions, the SA model is insensitive to capturing the effects of laminarization and the reenergization of eddy viscosity. The latter promotes the momentum transfer and correct reattachment prior to the fan face. Through distinct modules, the SA model has been modified to account for the effect of laminarization and separation induced transition. The modules have been implemented in the Rolls-Royce HYDRA computational fluid dynamic (CFD) solver. They have been validated over a number of experimental test cases involving laminarization and also surface roughness. The validated modules are finally applied in unsteady Reynolds-averaged Navier–Stokes (URANS) mode to flow around an engine intake and comparisons made with measurements. Encouraging agreement is found and hence advances made towards a more reliable intake design framework.

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References

Figures

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Fig. 2

Key flow physics zones

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Fig. 1

Modular nature of Boeing SA model

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Fig. 3

Geometry used for cases 1–5. (a) Cases 1 and 3, (b) case 2, and (c) cases 4 and 5.

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Fig. 4

Grid independence study for mesh 1 = 6 × 106 grid nodes and mesh 2 = 26 × 106 grid nodes for normalized lip isentropic Mach number plotted against the normalized lip axial length, for MaEX = 0.50 and ReD = 7 × 105

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Fig. 5

A 3D 90 deg sector intake rig mesh and lip: (a) mesh with every third grid line omitted and (b) lip zone

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Fig. 14

Nondimensional mean axial velocity profile at X = 1.603 m

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Fig. 15

Log mean velocity profile for fully rough regime hS+ = 220

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Fig. 16

Axial variation of Cf for fully rough regime hS+ = 220

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Fig. 7

Variation of momentum thickness Reynolds number with acceleration parameter

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Fig. 8

Log mean velocity profile for KS = 1.5 × 10−6 and 2.5 × 10−6 for the modified and the standard SA model

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Fig. 9

Wall normal variation of Reynolds shear stress for KS values

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Fig. 10

Axial variation of H for Warnack's geometry

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Fig. 6

Variation of shape factor with acceleration parameter

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Fig. 11

Axial variation of Cf for Warnack's geometry

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Fig. 12

Axial variation of R2 for Warnack's geometry

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Fig. 13

Nondimensional Reynolds shear stress profile for Warnack's geometry at X = 1.603 m

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Fig. 17

Log mean velocity profile for fully rough lower limit case hS+ = 70

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Fig. 23

Grid independence study for mesh 1 = 6 × 106 grid node and mesh 2 = 26 × 106 grid node for normalized mean velocity at the highlight

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Fig. 24

Grid independence study for mesh 1 = 6 × 106 grid node and mesh 2 = 26 × 106 grid node for normalized mean velocity at the fan face

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Fig. 25

Grid independence study for mesh 1 = 6 × 106 grid node and mesh 2 = 26 × 106 grid node for shear stress at the highlight

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Fig. 26

Grid independence study for mesh 1 = 6 × 106 grid node and mesh 2 = 26 × 106 grid node for shear stress at the fan face

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Fig. 18

Axial variation of Cffor fully rough lower limit case hS+ = 70

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Fig. 19

Stream lines showing separation bubble. (a) Standard model and (b) modular “three-component SA model.”

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Fig. 21

Stagnation pressure ratio plotted against normalized fan radius for MaEX = 0.55 and ReD = 7 × 105

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Fig. 22

Normalized lip isentropic Mach number plotted against the normalized axial length for rough surface MaEX = 0.55 and hs+ = 75.5

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Fig. 20

Normalized lip isentropic Mach number plotted against the normalized lip axial length for MaEX = 0.55 and ReD = 7 × 105

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