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Research Papers

HP Vane Aerodynamics and Heat Transfer in the Presence of Aggressive Inlet Swirl

[+] Author and Article Information
Imran Qureshi

Department of Engineering Science,
University of Oxford, Parks Road,
Oxford, OX1 3PJ, UK
e-mail: imran.qureshi@rolls-royce.com

Andy D. Smith

Turbine Sub-systems,
Rolls-Royce PLC, Moor Lane,
Derby, DE24 8BJ, UK

Thomas Povey

Department of Engineering Science,
University of Oxford, Parks Road,
Oxford, OX1 3PJ, UK

1Corresponding author. Present address: Rolls-Royce PLC, PCF-2, P.O. Box 31, Derby, DE24 8BJ.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received October 19, 2011; final manuscript received October 26, 2011; published online November 19, 2012. Editor: David Wisler.

J. Turbomach 135(2), 021040 (Nov 19, 2012) (13 pages) Paper No: TURBO-11-1230; doi: 10.1115/1.4006610 History: Received October 19, 2011; Revised October 26, 2011

Modern lean burn combustors now employ aggressive swirlers to enhance fuel-air mixing and improve flame stability. The flow at combustor exit can therefore have high residual swirl. A good deal of research concerning the flow within the combustor is available in open literature. The impact of swirl on the aerodynamic and heat transfer characteristics of an HP turbine stage is not well understood, however. A combustor swirl simulator has been designed and commissioned in the Oxford Turbine Research Facility (OTRF), previously located at QinetiQ, Farnborough UK. The swirl simulator is capable of generating an engine-representative combustor exit swirl pattern. At the turbine inlet plane, yaw and pitch angles of over ±40 deg have been simulated. The turbine research facility used for the study is an engine scale, short duration, rotating transonic turbine, in which the nondimensional parameters for aerodynamics and heat transfer are matched to engine conditions. The research turbine was the unshrouded MT1 design. By design, the center of the vortex from the swirl simulator can be clocked to any circumferential position with respect to HP vane, and the vortex-to-vane count ratio is 1:2. For the current investigation, the clocking position was such that the vortex center was aligned with the vane leading edge (every second vane). Both the aligned vane and the adjacent vane were characterized. This paper presents measurements of HP vane surface and end wall heat transfer for the two vane positions. The results are compared with measurements conducted without swirl. The vane surface pressure distributions are also presented. The experimental measurements are compared with full-stage three-dimensional unsteady numerical predictions obtained using the Rolls Royce in-house code Hydra. The aerodynamic and heat transfer characterization presented in this paper is the first of its kind, and it is hoped to give some insight into the significant changes in the vane flow and heat transfer that occur in the current generation of low NOx combustors. The findings not only have implications for the vane aerodynamic design, but also for the cooling system design.

Copyright © 2013 by ASME
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References

Figures

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Fig. 7

Yaw angle profile at 20% and 80% span; comparison of measurements in the OTRF with the target profile

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Fig. 8

Normalized inlet total pressure profile with swirl

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Fig. 9

Schematic to show notation used to refer to HP vane geometric alignment with respect to the vortex center

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Fig. 10

Predicted difference of inlet incidence angle with inlet swirl; 0.25 axial chords upstream of the vane leading edge

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Fig. 6

Measured inlet secondary flow vectors (bold arrows) and interpolated/extrapolated vectors (thin arrows)

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Fig. 5

Yaw angle profile measured 0.7 Cax upstream of NGV inlet plane with inlet swirl

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Fig. 4

Pitch angle profile measured 0.7 Cax upstream of NGV inlet plane with inlet swirl

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Fig. 3

The assembled inlet swirl simulator module

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Fig. 2

The working section of the OTRF with the HP turbine stage and turbobrake highlighted

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Fig. 1

Schematic of the Oxford turbine research facility

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Fig. 11

Predicted streamlines for uniform flow (blue) and flow with inlet swirl (red), showing shift of the stagnation line

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Fig. 12

NGV isentropic Mach number at 10% span for uniform inlet conditions and inlet swirl for position C1; comparison of measurements and CFD

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Fig. 13

NGV isentropic Mach number at 50% span for uniform inlet conditions and inlet swirl for position C1; comparison of measurements and CFD

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Fig. 14

NGV isentropic Mach number at 90% span for uniform inlet conditions and inlet swirl for position C1; comparison of measurements and CFD

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Fig. 15

NGV isentropic Mach number at 10% span for uniform inlet conditions and inlet swirl for position C2; comparison of measurements and CFD

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Fig. 16

NGV isentropic Mach number at 50% span for uniform inlet conditions and inlet swirl for position C2; comparison of measurements and CFD

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Fig. 17

NGV isentropic Mach number at 90% span for uniform inlet conditions and inlet swirl for position C2; comparison of measurements and CFD

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Fig. 18

Predicted pressure loss coefficient difference at vane exit between swirl and uniform conditions; position C1

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Fig. 19

Predicted pressure loss coefficient difference at vane exit between swirl and uniform conditions; position C2

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Fig. 20

Predicted radial pressure loss coefficient distributions downstream of NGV for uniform inlet conditions and for inlet swirl in positions C1 and C2

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Fig. 21

Predicted passage streamlines at 10%, 50%, and 90% span for uniform inlet conditions

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Fig. 22

Predicted passage streamlines at 90%, span for inlet swirl

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Fig. 23

Predicted passage streamlines at 50%, span for inlet swirl

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Fig. 24

Predicted passage streamlines at 10%, span for inlet swirl

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Fig. 25

Difference of secondary flow velocity vectors between swirl and uniform; 0.25Cax upstream of inlet

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Fig. 26

Difference of secondary flow velocity vectors between swirl and uniform at NGV inlet plane

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Fig. 27

Difference of secondary flow velocity vectors between swirl and uniform; 0.25Cax downstream of inlet

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Fig. 28

Difference of secondary flow velocity vectors between swirl and uniform, at NGV exit plane

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Fig. 29

Predicted NGV surface flow streamlines, with and without inlet swirl

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Fig. 30

NGV Nu at 10% span; uniform and swirl-C1

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Fig. 31

NGV Nu at 50% span; uniform and swirl-C1

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Fig. 32

NGV Nu at 90% span; uniform and swirl-C1

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Fig. 33

NGV Nu at 10% span; uniform and swirl-C2

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Fig. 34

NGV Nu at 50% span; uniform and swirl-C2

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Fig. 35

NGV Nu at 90% span; uniform and swirl-C2

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Fig. 36

Hub end wall Nusselt number with uniform inlet conditions (a) measured (b) predicted

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Fig. 37

Casing end wall Nusselt number with uniform inlet conditions (a) measured (b) predicted

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Fig. 38

Predicted surface flow streamlines, with and without inlet swirl: hub end wall

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Fig. 39

Predicted surface flow streamlines, with and without inlet swirl: casing end wall

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Fig. 40

Predicted hub end wall Nu (a) uniform (b) swirl

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Fig. 41

Predicted casing end wall Nu (a) uniform (b) swirl

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Fig. 42

Hub end wall Nu, with and without inlet swirl

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Fig. 43

Casing end wall Nu, with and without inlet swirl

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