Temperature measurement of turbine blade based on visible multispectral radiation

To reduce the measurement uncertainties resulted from the emissivity variation of blade surfaces and radiation from surrounding high-temperature gases when using traditional infrared radiation methods to measure the temperature of turbine blades in aircraft engines, a multispectral temperature measurement method based on the visible radiation was developed based on a multi-objective constrained optimization model. A hybrid penalty function approach was used to simultaneously calculate the temperature and spectral emissivity of the measured object. Meanwhile, the visible radiation of high-temperature gases was evaluated. These efforts were performed to reduce the error induced by the inaccuracy of the spectral emissivity model and the interference from radiation of high-temperature gases. Experiments were performed to validate the proposed method. In the experiments, nickel and nickel-based high-temperature alloy samples were heated using a butane flame gun within a temperature range of 1000 K to 1200 K. Additionally, a premixed methane-air planar flame furnace was utilized to provide a high-temperature gas environment with gas temperatures ranging from 1400 K to 1580 K. The surface temperature of the samples was simultaneously measured using multispectral radiation method and thermocouples. The comparison experiments showed that the relative error between the method and the thermocouple measurement was below 1.74%.