Scanning And Correction Of Two-dimensional Infrared Temperature Field Of Blade

Gas turbines are widely used in many neighbourhoods such as aerospace,ship power,and power development due to their ultra-high thermal efficiency and excellent power output capabilities.The turbine blade inside the gas turbine is the core hot-end component of the gas turbine.Under high temperature,high pressure,and high-speed rotating working conditions,the blade structure bears a huge working load,and it is easy to produce serious accidents such as cracks,deformation and even breakage during operation.The life of the turbine blade largely determines the overall overhaul period of the gas turbine,so the real-time monitoring of the surface temperature of the turbine blade has a profound impact on the reliability research of the gas turbine.By realizing the measurement of the blade surface temperature field,not only the real-time monitoring of the operating conditions of the gas turbine,but also the analysis and verification of the blade’s processing technology and cooling efficiency are very important.In this paper,the numerical simulation of the surface temperature field of turbine blades by the finite volume method is carried out by using the computational fluid dynamics method.A data change model of the surface temperature and pressure of the blades under the normal operation of a gas turbine is established.According to the temperature field distribution characteristics obtained from the simulation calculation and the structural characteristics of the probe,a temperature measurement optical path model is constructed in this paper,and the temperature measurement optical path and the dynamic process of temperature measurement are simulated.By realizing the scanning of the scanning optical path in the radial direction of the blade,the scanning measurement of the two-dimensional infrared temperature field on the surface of the blade can be completed during the high-speed rotation of the blade.By comparing the effects of traditional pyrometers and scanning pyrometers on the blade surface temperature,it is verified that the scanning temperature measurement scheme has a more complete characterization of the blade surface temperature field distribution.The change in the angle of the radiation temperature measurement optical path and the shape and size of the temperature measurement point on the blade surface will cause the infrared spectrum energy captured by the temperature measurement probe to change,and then affect the photoelectric conversion efficiency,thereby affecting the radiation temperature measurement result.By simulating the influence of light path structure and light spot changes,the temperature measurement effect of the scanning probe under different states is studied and analyzed.This paper proposes four scanning temperature measurement schemes,and analyzes the temperature measurement effects and characteristics of each scheme.By analyzing the influence of the internal parameters of the probe on the angle of the light path and the temperature measurement distance,a calculation algorithm for the temperature measurement position coordinates of the blade surface is proposed.By analyzing the changes of the light path angle and the shape of the disc during the rotation of the scanning radiation temperature probe during scanning,the compensation and correction methods of the radiation temperature on the surface of the blade are obtained.At the same time,the effect of emissivity on radiation temperature measurement was studied.In this paper,by designing the blade surface emissivity measurement experiment,the influence of the blade surface thermal barrier coating thickness on the emissivity and the fitting function of the blade surface emissivity with wavelength and temperature were optimized.The choice of temperature measurement spectral band is provided,which provides conditions for further optimization and improvement of radiation temperature measurement methods.