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TECHNICAL PAPERS

The Effect of Hot-Streaks on HP Vane Surface and Endwall Heat Transfer: An Experimental and Numerical Study

[+] Author and Article Information
T. Povey, T. V. Jones, J. Hurrion

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

K. S. Chana

 QinetiQ, Cody Technology Park, Ively Road, Farnborough, GU14 0LX, UK

J. Turbomach 129(1), 32-43 (Feb 01, 2005) (12 pages) doi:10.1115/1.2370748 History: Received October 01, 2004; Revised February 01, 2005

Pronounced nonuniformities in combustor exit flow temperature (hot-streaks), which arise because of discrete injection of fuel and dilution air jets within the combustor and because of endwall cooling flows, affect both component life and aerodynamics. Because it is very difficult to quantitatively predict the effects of these temperature nonuniformities on the heat transfer rates, designers are forced to budget for hot-streaks in the cooling system design process. Consequently, components are designed for higher working temperatures than the mass-mean gas temperature, and this imposes a significant overall performance penalty. An inadequate cooling budget can lead to reduced component life. An improved understanding of hot-streak migration physics, or robust correlations based on reliable experimental data, would help designers minimize the overhead on cooling flow that is currently a necessity. A number of recent research projects sponsored by a range of industrial gas turbine and aero-engine manufacturers attest to the growing interest in hot-streak physics. This paper presents measurements of surface and endwall heat transfer rate for a high-pressure (HP) nozzle guide vane (NGV) operating as part of a full HP turbine stage in an annular transonic rotating turbine facility. Measurements were conducted with both uniform stage inlet temperature and with two nonuniform temperature profiles. The temperature profiles were nondimensionally similar to profiles measured in an engine. A difference of one-half of an NGV pitch in the circumferential (clocking) position of the hot-streak with respect to the NGV was used to investigate the affect of clocking on the vane surface and endwall heat transfer rate. The vane surface pressure distributions, and the results of a flow-visualization study, which are also given, are used to aid interpretation of the results. The results are compared to two-dimensional predictions conducted using two different boundary layer methods. Experiments were conducted in the Isentropic Light Piston Facility (ILPF) at QinetiQ Farnborough, a short-duration engine-sized turbine facility. Mach number, Reynolds number, and gas-to-wall temperature ratios were correctly modeled. It is believed that the heat transfer measurements presented in this paper are the first of their kind.

Copyright © 2007 by American Society of Mechanical Engineers
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Figures

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Figure 1

Schematic of the ILPF

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Figure 2

The working section of the ILPF: HP turbine stage and turbobrake

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Figure 3

Typical measured combustor exit temperature profile

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Figure 4

Measured inlet temperature profiles: OTDF1 and OTDF2

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Figure 5

Comparison of the ILPF radial temperature profile with typical engine profile

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Figure 6

Thin film gauges on the HP vane PS at 50% span

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Figure 7

Heat transfer gauges on the HP vane hub and case endwalls

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Figure 8

HP vane isentropic Mach number at 10, 50, and 90% span

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Figure 9

Surface flow visualization on the HP vane SS (13)

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Figure 10

Measured HP vane surface Nusselt number distribution

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Figure 14

Schematic of the 50 percent span streamlines for OTDF1 and OTDF2

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Figure 15

Nusselt number on the HP vane hub endwall with and without ITD

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Figure 16

Nusselt number on the HP vane case endwall with and without ITD

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Figure 11

Integral Method prediction for HP vane surface Nu compared to experimental data

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Figure 12

Integral method and TEXSTAN predictions for HP vane surface Nu compared to experimental data

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Figure 13

Comparison of HP vane surface Nusselt number distribution with and without ITD at 50% span

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