Phosphor thermometry in gas turbines: Consideration factors

There is an increasing demand for turbine engines with improved performance and efficiency. Gas turbine efficiencies can be increased if higher turbine inlet temperatures are achieved. However, the optimum temperature is prescribed by the balance between the benefits of thermal efficiency and material life. Accurate thermal maps can allow engines to operate closer to their design limit, and greatly facilitate the design of improved engines. This article provides a review highlighting the advantages and rationale of using phosphor thermometry over existing temperature measurement techniques, such as thermocouple and pyrometry. Although phosphor thermometry exhibits excellent characteristics to make accurate measurements, the high temperature and fast rotating engine environment presents some challenges with interrelated issues that would need to be collectively considered before a successful measurement system can be implemented. Examples include extreme blackbody radiation, restricted optical access and time to collect data, etc. These factors will impose temperature limits and greatly influence the design philosophy of the measurement system, including phosphor choice, bonding technique, excitation/detection methodologies, and probe design. This article aims to provide an overview of these consideration factors, with supplementary design notes and guidance to aid engineers design and develop successful phosphor thermometry measurement systems for such environments.