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Research Papers: Flows in Complex Systems

CFD Analysis of Gear Windage Losses: Validation and Parametric Aerodynamic Studies

[+] Author and Article Information
Matthew J. Hill

Department of Aerospace Engineering, Pennsylvania State University, University Park, PA 16802mjh414@psu.edu

Robert F. Kunz

Applied Research Laboratory, Pennsylvania State University, University Park, PA 16802rfk102@arl.psu.edu

Richard B. Medvitz

Applied Research Laboratory, Pennsylvania State University, University Park, PA 16802rbm120@arl.psu.edu

Robert F. Handschuh

 NASA Glenn Research Center, Cleveland, OH 44135robert.f.handschuh@nasa.gov

Lyle N. Long

Department of Aerospace Engineering, Pennsylvania State University, University Park, PA 16802lnl@psu.edu

Ralph W. Noack

Applied Research Laboratory, Pennsylvania State University, University Park, PA 16802rwn10@arl.psu.edu

Philip J. Morris

Department of Aerospace Engineering, Pennsylvania State University, University Park, PA 16802pjmaer@engr.psu.edu

J. Fluids Eng 133(3), 031103 (Mar 16, 2011) (10 pages) doi:10.1115/1.4003681 History: Received August 23, 2010; Revised January 30, 2011; Published March 16, 2011; Online March 16, 2011

A computational fluid dynamics (CFD) method has been applied to gear configurations with and without shrouding. The goals of this work have been to validate the numerical and modeling approaches used for these applications and to develop physical understanding of the aerodynamics of gear windage loss. Several spur gear geometries are considered, for which experimental data are available. Various canonical shrouding configurations and free spinning (no shroud) cases are studied. Comparisons are made with experimental data from open literature, and data recently obtained in the NASA Glenn Research Center Gear Windage Test Facility, Cleveland, OH. The results show good agreement with the experiment. The parametric shroud configuration studies carried out in the Glenn experiments and the CFD analyses elucidate the physical mechanisms of windage losses as well as mitigation strategies due to shrouding and newly proposed tooth contour modifications.

Copyright © 2011 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Comparison of Diab gear 1 and disk grids

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Figure 2

Comparison of results from experiment (4), NPHASE-PSU (15), and OVER-REL for Diab gears 1–4

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Figure 3

Comparison of results from experiment (4) and OVER-REL for Diab gear 1. Viscous and pressure loss budgets are included.

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Figure 4

Comparison of Diab gear 1 and disk measurements and OVER-REL solutions

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Figure 5

Comparison of predicted torque per unit span contributed by viscous shear for the Diab disk (up to its outer radius) and gear 1 (up to its base radius)

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Figure 6

Three-dimensional relative frame streamlines colored by static pressure for Diab gear 1 at 850 rad/s

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Figure 7

Axial projection of velocity vectors halfway between gear face and gear centerline for Diab gear 1 at 850 rad/s. Vector density of 0.5. Background contours of local normalized projected relative velocity magnitude.

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Figure 8

Axial projection of velocity vectors near-gear centerline for Diab gear 1 at 850 rad/s. Vector density of 0.5. Background contours of local normalized projected relative velocity magnitude.

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Figure 9

ΔCP between gear leading and trailing tooth surfaces (one-half of symmetrical gear shown) for Diab gear 1 at 850 rad/s

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Figure 10

Pressure torque per unit width versus axial coordinate (one-half of symmetrical gear shown) for Diab gear 1 at 850 rad/s

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Figure 11

Four notional shroud configurations for Diab gear 1 geometry. Figure is to scale. The gray region defines the gear. The solid black lines indicate the positions of the large-axial and large-radial shroud walls. The dashed lines indicate the positions of the small-axial and small-radial shroud walls.

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Figure 12

Cross section of overset mesh topology for the small-radial shroud

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Figure 13

Comparison of predicted windage losses between free spinning Diab gear 1 and four shrouded configurations

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Figure 14

Comparison of predicted windage losses between four shrouded Diab gear 1 configurations

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Figure 15

ΔCP between gear leading and trailing tooth surfaces (one-half of symmetrical gear shown). Diab gear 1, large-axial-large-radial shroud, 850 rad/s.

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Figure 16

Contours of pressure and surface shear stress lines on the leading surface for the four shrouded cases at 850 rad/s

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Figure 17

Plot of torque per unit width from the gear face for the four shrouded cases

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Figure 18

Comparison of viscous torque per unit span for Diab gear 1 at 850 rad/s for the unshrouded and four shrouded configurations

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Figure 19

Overview sketch of the NASA Glenn Research Center Gear Windage Test Facility (5)

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Figure 20

Shroud assembly for test facility (5)

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Figure 21

Experimental (5) and CFD results for the 13″ pitch diameter NASA spur gear

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Figure 22

Three-dimensional relative frame streamlines colored by static pressure for the NASA 13″ pitch diameter spur gear, large-axial-large-radial shroud, at 700 rad/s

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Figure 23

Predicted surface pressure coefficient and skin friction lines for baseline tooth geometry

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Figure 24

Predicted surface pressure coefficient and skin friction lines for tooth geometry alternative: leading surface rounding

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Figure 25

Predicted surface pressure coefficient and skin friction lines for tooth geometry alternative: leading+trailing surface rounding

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Figure 26

Predicted surface pressure coefficient and skin friction lines for tooth geometry alternative: tooth slot

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Figure 27

Predicted surface pressure coefficient and skin friction lines for tooth geometry alternative: trailing surface ramp

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Figure 28

Windage loss predictions for the baseline tooth geometry (Diab gear 1 with large-axial-large-radial shroud) and four geometric alternatives

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Figure 29

Torque per unit width predictions for the baseline tooth geometry (Diab gear 1 with large-axial-large-radial shroud) and four geometric alternatives at 850 rad/s

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