Abstract

With the advent of "power by the hour" type agreements within the civil aeroengine market, the application of engine monitoring system data has reached the level of strategic use for informed decision making in not only the aftermarket but increasingly in the contract negotiation stage. One of the key cost drivers in these dollar-per-hour contracts for the OEMs to analyze is the life and maintenance requirements of the turbine blades leading ultimately to blade life management. Such life management of key components is of critical importance to ensure that the economic and technical risks to both service provider and customer are minimized. The optical pyrometer, through providing a direct temperature measurement of the turbine blades, is a primary input for providing a more realistic assessment of the component’s operating history associated with the use of life usage/remaining algorithms. However, the greatest concern with the in-service use of pyrometry is the issue of fouling since the pyrometer’s lens is exposed to the turbine environment. The level of optical contamination is usually minimized by introducing purge air, bled from the compressor, down the sight tube to prevent both the build-up of contaminants on the exposed system optics and particles in the gas stream from coming in contact with the lens. This paper provides a review of purge air designs and the key methodologies for engine designers to be acquainted with when seeking to integrate the use of optical pyrometry systems in new engine concepts.

Issue Section:
Technical Papers
Keywords:
gas turbines, temperature measurement, pyrometers, civil engineering, aircraft, cost-benefit analysis
Topics:
Air flow, Flow (Dynamics), Lenses (Optics), Particulate matter, Pyrometers, Turbines, Design, Contamination, Engines
1.
De Lucia
,
M.
, and
Lanfranchi
,
C.
,
1994
, “
An Infrared Pyrometry System for Monitoring Gas Turbine Blades: Development of a Computer Model and Experimental Results
,”
ASME J. Eng. Gas Turbines Power
,
116
, pp.
172
–
177
.
2.
Sellers, R. R., Przirembel, H. R., Clevenger, D. H., and Lang, J. L., 1989, “The Use of Optical Pyrometers in Axial Flow Turbines,” AIAA/ASME/SAE/ASEE 25th Joint Propulsion Conference, Monterey, July 10–12, AIAA-89-2692.
3.
Kirby, P. J., 1986, “Some Considerations Relating to Aero Engine Pyrometry,” Advance Instrumentation for Aero Engine Components, The Propulsion and Energetics Panel 67th Symposium, Philadelphia, May 19–23, 1986. AGARD-CP-399.
4.
Davinson, I., 1984, “Detection of and Correction for Lens Contamination in Radiation Pyrometers, EIR 00862. Rolls-Royce Limited, Derby, England.
5.
Atkinson, W. H., and Guenard, R. N., 1978 “Turbine Pyrometry in Aircraft Engines,” IEEE/ERA Electro-78 Conference Record Session 33/3, Boston, MA, May 23–25.
6.
Barber, R., 1969, “A Radiation Pyrometer Designed for Inflight Measurement of Turbine Blade Temperatures,” National Air Transportation Meeting, New York, NY, April 21–24, SAE 690432.
7.
Berenblut
,
B. J.
, and
Masom
,
R. A.
,
1982
, “
Radiation Pyrometry for Gas Turbine Engines—An Introduction
,”
Br. J. Non-Destr. Test.
,
24
(
5
),
268
–
269
.
8.
Hayden, T., Myhre, D., Pui, D. Y. H., Kuehn, T. H., and Tsai, C. J., 1988, “Evaluating Lens Purge Systems for Optical Sensors on Turbine Engines,” AIAA/ASME/SAE/ASEE 24th Joint Propulsion Conference, Boston, MA, July 11–13, AIAA-88-3037.
9.
Myhre, D. C., Pui, D. Y. H., and Miller, L. V., 1988, “Purge Air System for a Combustion Instrument,” Rosemount, US 4,786,188.
10.
O’Brien, R. J., and Myhre, D. C., 1989, “Asymmetric Purge Air System for Cleaning a Lens,” Rosemount, US 4,836,689.
11.
Holmqvist, G., Kallon, S., and Jansson, B., 1980, “Protective Device for Optical Elements,” AGA Aktiebolag, US 4,240,691.
12.
De La Mora
,
J. F.
,
Rao
,
N.
, and
McMurry
,
P. H.
,
1990
, “
Inertial Impaction of Fine Particles at Moderate Reynolds Numbers and in the Transonic Regime With a Thin-Plate Orifice Nozzle
,”
J. Aerosol Sci.
,
21
(
7
), pp.
889
–
909
.
13.
Biswas
,
P.
, and
Flagan
,
R. C.
,
1988
, “
The Particle Trap Impactor
,”
J. Aerosol Sci.
,
19
(
1
), pp.
113
–
121
.
14.
MacKay, C. G., 1990, “Temperature Measurement in Turbine Engines,” Allied-Signal Inc, US 4,934,137.
15.
Penney, C. M., and Lund, R. M., 1988, “System to Protect Optics Against Dirty Environments,” General Electric Company, US 4,784,491.
16.
Craft, D. W., 1988, “Pyrometer Vortex Purge Air Cleaning System With Center Masked Pyrometer Lens,” General Electric Company, US 4,738,528.
17.
Myhre, D. C., O’Brien, R. J., Pui, D. Y. H., and Tsai, C. J., 1992, “Window Purging System for a Combustion Instrument,” Rosemount, US 5,146,244.
18.
Harley, J. F., 1981, “Air Purging for an Optical Pyrometer of a Gas Turbine Engine,” Avcu Corporation, US 4,306,835.
19.
Pointer, J., and Masom, R. A., 1985, “Radiation Pyrometer,” Smiths Industries Public Limited Company, GB 2,158,576.
20.
Ridley, I. H., and Fearnehough, P., 1997, “Purge Assembly,” Land Instruments International Limited, US 5,599,105.
21.
Kast, H. B., and Prasad, M. E., 1995, “Pyrometer Adapter,” General Electric Company, US 5,421,652.
22.
Suarez-Gonzalez, E., and Kepple, D. A., 1987, “In-flight Engine Control Optical Pyrometer,” United Technologies Corporation, US 4,657,386.
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