Analyzing the influence of combustion gas on a gas turbine by radiation thermometry

High temperature is the main focus in ongoing development of gas turbines. With increasing turbine inlet temperature, turbine blades undergo complex thermal and structural loading subjecting them to large thermal gradients and, consequently, severe thermal stresses and strain. In order to improve the reliability, safety, and service life of blades, accurate measurement of turbine blade temperature is necessary. A gas turbine can generate high-temperature and high-pressure gas that interferes greatly with radiation from turbine blades. In addition, if the gas along the optical path is not completely transparent, blade temperature measurement is subject to significant measurement error in the gas absorption spectrum. In this study, we analyze gas turbine combustion gases using the κ-distribution method combined with the HITEMP and HITRAN databases to calculate the transmission and emissivity of mixed gases. We propose spectral window methods to analyze the radiation characteristics of high-temperature gas under different spectral ranges, which can be used to select the wavelengths used in multispectral temperature measurement on turbine blades and estimate measurement error in the part of the spectrum with smaller influence (transmission > 0.98).