An Infrared Pyrometry System for Monitoring Gas Turbine Blades: Development of a Computer Model and Experimental Results

Abstract

This work describes the development of a computer modeling system for infrared pyrometry measurement of gas turbine blade temperature. The model accurately evaluates apparent target emissivity and temperature on the basis of the radiation heat fluxes exchanged at steady-state conditions. Experimental testing conducted on gas turbine models in a controlled-temperature furnace has shown that the reliability of the target emissivity prediction effectively reduces one of the major causes of error in infrared pyrometry.

Aero-Thermal Design and Testing of Advanced Turbine Blades

“…The principal focus of research work on the use of infrared thermometry in gas turbines in the recent years was the development of computer models for the application and evaluation of this technique e.g. by De Lucia and Lanfranchi (1992) and De Lucia and Masotti (1995).…”

A Scanning Radiation Thermometry Technique for Determining Temperature Distribution in Gas Turbines

“…The static model used in experimental testing is schematically illustrated in Figure 1. Like the earlier version (De Lucia and Lanfranchi, 1992), it is composed of two stator vanes and two rotor blades instrumented with K type thermocouples (precision: 0.4-0.7%) simulating a 10MW heavy-duty gas turbine. The model has been redesigned for displacement capabilities and with optimized cooling and radiation thermometer-positioning systems.…”

“…The literature provides several integrated formulas for calculating angle factors for elementary known geometries with appropriate approximations (Bejan, 1993;De Lucia and Lanfranchi, 1992;1Creith, 1973;Sparrow and Cess, 1978). The two most promising solutions were examined: the model proposed by Bejan (1993) hereinafter designated model A, which was adapted and implemented to account for the finite dimensions and the top and bottom surfaces, and the model proposed by De Lucia and Lanfranchi (1992), hereinafter designated model B. Figures 3 and 4, Bejan's formula for two thin, facing-plane, isothermal surfaces integrated between -h/2 ans he2 is…”

“…To account for the top and bottom edges, we used (De Lucia and Lanfranchi, 1992) F=-1-5 [satin +sni)-sin(yi)] • {xi tan -1 (1 -xi tan -1 () + 23r.,4…”

“…With noncontact radiation thermometers, temperatures can be measured in the harshest environments, especially when moving components are involved. In an earlier paper, De Lucia and Lanfranchi (1992) proposed a radiation thermometry model based on the use of theoretical temperature distributions to correct target temperature. This work presents an enhanced version of the earlier system which enables the determination of temperature distribution on the basis of multiple radiation thermometer measurements.…”