Validation of Surface Temperature Measurements on a Combustor Liner Under Full-Load Conditions Using a Novel Thermal History Paint

Abstract

The ever-increasing requirements on gas turbine efficiency and the simultaneous demand for reduced emissions, necessitate much more accurate calculations of the combustion process and combustor wall temperatures. Thermal history paints (THPs) is an innovative alternative to the established measurement techniques, but so far only a limited number of tests have been conducted under real engine conditions. A typical THP comprises oxide ceramic pigments and a water-based binder. The ceramic is synthesized to be amorphous and when heated it crystallizes, permanently changing the microstructure. The ceramic is doped with lanthanide ions to make it phosphorescent and as the structure of the material changes, so do the phosphorescent properties of the material. By measuring the phosphorescence, the maximum temperature of exposure can be determined, enabling postoperation measurements at ambient conditions. This paper describes a test in which THP was applied to an impingement-cooled front panel from a combustor of an industrial gas turbine. The panel was instrumented with a thermocouple (TC), and thermal paint was applied to the cold side of the impingement plate. The THP was applied to the hot-gas side of this plate for validation against the other measurement techniques and to evaluate its resilience against the reacting hot gas environment. The durability and temperature results of the three different measurement techniques are discussed. It is shown that the THP exhibited greater durability compared to the conventional thermal paint. Furthermore, the new technology provided detailed measurements indicating local temperature variations and global variations over the complete component.

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

“…The technique has been successfully demonstrated to temperatures up to 900°C with a precision better than ±5 °C (Feist et al, 2015). Recently, THPs were tested in a combustor chamber test and compared favourably with thermochromic paints (Krewinkel et al, 2017) in terms of measurement capability and durability. The greater durability than thermochromic paints, affords the opportunity to use this technique as part of extended tests.…”

“…The second stage blades were measured with a newly developed, dedicated system whereby the head of the optical fibre was attached to 3 linear slides that permitted movement in 3 dimensions, described in more detail elsewhere (Krewinkel et al, 2017). Additionally, the blades were mounted on a rotary table that allowed rotation around the vertical axis.…”

High-Pressure Route to Irreversible Thermochromic Materials

“…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. ,, …”

Photocured Organofunctional Silicon-Based Polymer and Its Y2O3 Nanocomposite as the Luminescence Tracer of Thermal History

“…Polymer materials with irreversible thermally switched luminescence are of high practical importance. These materials can be used as luminescence tracers for monitoring the quality and storage conditions of materials or for the detection of overheated zones in the specified range of temperatures in electronic, optical, mechanical devices, and so forth. − …”