Objective  With the rapid development of national defense industry and science and technology, more in-depth application and research of gas turbine engines in aviation, power generation, chemical industry, ship and power engineering are also conducted. Due to the complex working environment of turbine blades, the particularity of temperature measurement, and the interference of wall and gas radiation, the traditional temperature measurement technology has been unable to meet its needs. In order to accurately measure the working temperature of turbine blades in complex high-temperature environments, ensure that the highest temperature and temperature gradient on the blade surface are suitable for the blade design life, and improve the safety and efficiency of gas turbine operation, infrared temperature measurement technology was used to correct the temperature of the blades under high operating conditions.

  Methods  With a discretized pure three-dimensional model and a radiation correction method based on infrared temperature measurement of turbine blades, the temperature error verification calculation of turbine guide vanes with end walls was carried out using numerical simulation combined with User Defined Function (UDF) custom programming. Custom programming was used to perform reliability verification calculations on the classic concentric sphere model, such as angle coefficients and effective radiation. Based on this method, the angle coefficients of each grid element between the end wall and turbine guide vanes were calculated, and the radiation heat transfer between the blade surfaces was calculated. The surface radiation characteristics distribution of the turbine guide vanes was output, and the radiation energy flow distribution of the turbine guide vanes under this operating condition was derived using Boltzmann's law. We calculated and analyzed the temperature error distribution of turbine guide vanes with end walls under different error influence mechanisms, explored the influence of thermal radiation environment on blade surface radiation characteristics, and discussed the effect of effective radiation on turbine blade temperature measurement.

  Results and Discussions  From Figure 8, it can be seen that after convergence, as the inlet blackbody radiation temperature increases from 1400 K to 1800 K, the temperature at the trailing edge and pressure surface of the blade is higher. Under changing the temperature conditions of imported blackbody radiation, the impact on the wall temperature of the blade is mainly concentrated in the pressure surface area of the blade. The pressure surface temperature of the blade is significantly higher than that of the suction surface area, and the second most influential area is mainly the leading edge area of the blade; From Figure 10, it can be seen that as the outlet blackbody radiation temperature increases, the proportion of radiation heat flow rate gradually increases, and there is a significant temperature rise near the trailing edge wall of the suction surface. As shown in Figure 10 (b), (e), (h), the suction surface and trailing edge of the blade are more affected by the outlet blackbody radiation temperature. When the export blackbody radiation temperature is 1600 K, the calculated error of the blade suction surface and trailing edge is about 10 K. The impact area of the export blackbody radiation is mainly in the blade suction surface area, and the temperature rise is relatively small, which has not had a significant impact on the distribution of the outer surface of the blade; When the wall emissivity decreases from 0.8, 0.6, and 0.2, the temperature in the leading edge area of the blade pressure surface is less affected by the emissivity. The temperature error distribution of the effective radiation inverse calculation is shown in Figure 12. The larger the emissivity, the greater the error at the gill area of the blade pressure surface. From the error distribution Figure 13, it can be seen that the influence at the leading edge of the blade is greater than that in the middle area of the blade, and the influence in the pressure surface area of the blade is secondary to that of the suction surface.

  Conclusions  When the temperature of imported blackbody radiation is between 1 400 K and 1 800 K, the intensity of imported radiation has the greatest impact on blade heat transfer; Based on the effective radiation and the calculated error distribution, it can be concluded that the main area affected by the inlet radiation temperature is the leading edge area of the blade, with a maximum calculation error not exceeding 2.82%; Through effective radiation and error distribution, it can be seen that the change in outlet blackbody radiation temperature has a relatively small impact on the turbine guide vanes, and the temperature affected area is mainly the leading edge area of the blade. The maximum calculation error shall not exceed 2.35%; The emissivity of the blade surface is positively correlated with temperature. As the emissivity of the blade surface increases, the surface temperature of the blade uniformly rises accordingly. Under real operating conditions, the changes in the physical properties of blade materials are relatively small, and the impact of changes in physical parameters caused by blade temperature changes can be approximately ignored in engine design.