Experimental Investigation of Vane Clocking in a One and One-Half Stage High Pressure Turbine

[+] Author and Article Information
Charles W. Haldeman, Michael Dunn

 Gas Turbine Laboratory, Ohio State University, 2300 West Case Road, Columbus, OH 43235

John W. Barter, Brian R. Green, Robert F. Bergholz

 General Electric Aircraft Engines, Cincinnati, OH 45215

J. Turbomach 127(3), 512-521 (Mar 01, 2004) (10 pages) doi:10.1115/1.1861915 History: Received October 01, 2003; Revised March 01, 2004

Aerodynamic measurements were acquired on a modern single-stage, transonic, high-pressure turbine with the adjacent low-pressure turbine vane row (a typical civilian one and one-half stage turbine rig) to observe the effects of low-pressure turbine vane clocking on overall turbine performance. The turbine rig (loosely referred to in this paper as the stage) was operated at design corrected conditions using the Ohio State University Gas Turbine Laboratory Turbine Test Facility. The research program utilized uncooled hardware in which all three airfoils were heavily instrumented at multiple spans to develop a full clocking dataset. The low-pressure turbine vane row (LPTV) was clocked relative to the high-pressure turbine vane row (HPTV). Various methods were used to evaluate the influence of clocking on the aeroperformance (efficiency) and the aerodynamics (pressure loading) of the LPTV, including time-resolved and time-averaged measurements. A change in overall efficiency of approximately 2–3% due to clocking effects is demonstrated and could be observed using a variety of independent methods. Maximum efficiency is obtained when the time-average surface pressures are highest on the LPTV and the time-resolved surface pressure (both in the time domain and frequency domain) show the least amount of variation. The overall effect is obtained by integrating over the entire airfoil, as the three-dimensional (3D) effects on the LPTV surface are significant. This experimental data set validates several computational research efforts that suggested wake migration is the primary reason for the perceived effectiveness of vane clocking. The suggestion that wake migration is the dominate mechanism in generating the clocking effect is also consistent with anecdotal evidence that fully cooled engine rigs do not see a great deal of clocking effect. This is consistent since the additional disturbances induced by the cooling flows and∕or the combustor make it extremely difficult to find an alignment for the LPTV given the strong 3D nature of modern high-pressure turbine flows.

Copyright © 2005 by American Society of Mechanical Engineers
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Figure 3

Comparison of clocking effects based on measurement type

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Figure 4

Variations due to clocking, LPTV time-average values

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Figure 5

Variations in FFT amplitudes for LPTV

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Figure 6

Amplitude change for LPTV at 10% span

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Figure 7

Normalized pressure envelopes, LPTV all spans

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Figure 8

Variations in envelope size 10% span, LPTV

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Figure 9

LPTV 10% span normalized data

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Figure 1

Sketch of overall rig

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Figure 10

LPTV 50% span normalized pressure

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Figure 11

LPTV average pressures at 10% span

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Figure 12

LPTV average pressures at 90% span

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Figure 13

LPTV 10% span envelope sizes

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Figure 14

LPTV 90% span envelope sizes

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Figure 16

Total pressure at leading edge of LPTV

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Figure 15

Total pressure variation at 10% span, LPTV inlet




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