Surface Temperature Measurements in an Industrial Gas Turbine Using Thermal History Paints

Abstract

The measurement of surface temperatures of hot-gas path components of gas turbines under operating conditions provides a considerable challenge because the complexity of measurements under the prevailing conditions is substantial. The results from temperature measurements from an engine test using Thermal History Paint (THP) are presented here. The sensor material in the THP is an oxide ceramic which is doped with lanthanide ions to make the material luminescent. The properties of the luminescence depend on the temperature of exposure. The paper describes the first application of this technology in an extended, rather than dedicated, engine test in which components in both the hot gas path and the secondary air system were coated with THP. During the test campaign the engine components operated below maximum temperature for extended periods of time, which required a novel approach to the calibration of the paint. An overview over the correspondence between the temperatures measured with the THP, thermal paints and CFD calculations is provided for a sideplate and turbine blade. There is very good correlation between the results of the different methods. For the sideplate, the temperature measured with the THP was within 10K of the CFD calculation. Furthermore, the THP exhibited only minor erosion damage after over 50 hours of engine testing. The high durability and measurement accuracy demonstrate the feasibility of using the THP in extended engine tests.

Surface temperature condition monitoring methods for aerospace turbomachinery: exploring the use of ultrasonic guided waves

“…Precision of the measurement was ±5 • C, and results were within the min-max range of the thermocouple results. An extended test (around 50 hours) using THPs was carried out by Pilgrim [29]. No damage to the THP was observed, and results are in agreement with temperature sensitive paints and CFD models (10 • C difference between them).…”

A Review of NDT/Structural Health Monitoring Techniques for Hot Gas Components in Gas Turbines

“…The application in an industrial gas turbine was proven as well. The surface temperature of combustion chamber transition ducts, turbine blades and sideplates were measured and used for validation for the CFD calculations [205,206].…”

High-Pressure Route to Irreversible Thermochromic Materials

“…For example, lead, chromium, cobalt, and, in some cases, mercury are restricted by the REACH legislation in Europe. 18,23,24 Here, we propose a new material design that achieves hightemperature irreversible thermochromism without relying on chemical changes, which is applicable to inorganic materials that do not contain toxic elements. Our idea is based on two key factors, as conceptually illustrated in Figure 1.…”

“…Reversible thermochromic materials return to their original color when cooled after heating, making them useful for smart windows, temperature indicators, and other applications. ,,,− Irreversible thermochromic materials, on the other hand, exhibit an irreversible color change that depends on the maximum temperature reached during heating. The color does not revert to the original color after cooling, meaning that a permanent temperature history is preserved that can be visualized offline , Such irreversible thermochromism has been utilized as a temperature marker. − To date, irreversible thermochromism in solids is usually based on chemical changes such as thermal decomposition. ,,, However, this mechanism has potential drawbacks such as low durability and negative impacts on surroundings (e.g., metallurgical interactions due to gas contamination). − In addition, irreversible thermochromic materials that operate at high temperatures above 1000 °C often contain toxic elements restricted by many countries. For example, lead, chromium, cobalt, and, in some cases, mercury are restricted by the REACH legislation in Europe. ,, …”