Research On Turbine Blade Temperature Measurement Method With Working Environment Influence

Accurate measurement of turbine blade temperature has a very important significance for safe operation of gas turbine.The generally used method for gas turbine blade temperature measurement is radiation thermometry.However,the radiation and the absorption of high temperature gas combustion around the turbine blade and the reflection of high temperature background radiation near the turbine blade have a great influence on the accuracy of the radiation temperature measurement.The main aims of this research are to analyze the two working environmental factors for enhancing the on-line turbine blade temperature measurement precision.Finally,turbine blade temperature measurement method with working environment influence is proposed.High temperature gas around turbine blade absorbs blade radiation while itself radiates certain amount of radiation.Radiation pyrometers are designed to avoid the gas radiation spectrum,but with the development of multi-spectral thermometry and the limitation of optical devices,it is often difficult to completely avoid the gas radiation spectrum affecting spectral measurement.This paper studies gas radiation characteristics and absorptive capacity under different conditions by investigating the radiation characteristics of the mixed gas under high temperature and high pressure.The k distribution model is used to rearrange the spectral absorption coefficient which is drastically changed into a smooth monotonically increasing function.By comparing the existing gas radiation calculation method,the calculation precision and calculation speed of the method are verified.The method can correct gas influence on the measurement and provide important basis for spectrum optimization choice of radiation pyrometer.The amount of reflection formed on the surface of turbine blade directly affects the results of temperature measurement.In this paper,high background radiation temperature measurement method is proposed.The angle factor is used to describe the reflection energy,and the mathematical model of radiation temperature measurement is set up to reduce the influence of temperature measurement.It is difficult to solve the model directly after the reflection is added.Multi-spectral temperature measurement data processing is presented in this paper,in view of the reflection effects to establish goals,the search efficiency and calculation precision of the calculation results is improved.The effect of reflection on temperature measurement can effectively be reduced by a high temperature background effect experiment to be designed.Because the working environment of turbine blade is complicated,the reflection effect is different when the blades rotate to different positions hence it is difficult to calculate reflection directly.This dissertation presents a method to establish turbine blade background radiation reflection model,which can accurately describe the influence of the reflection on the temperature measurement.In the process of modeling,the high-order polynomial fitting method is used to replace the blade design parameters to construct the blade type line equation.At the same time,the curve mesh and the surface element method are used to deal with the model of turbine blade and adjacent hot end parts.Compared with the simple model of the method,fully irregular structure considering the blade surface,a more accurate description of the blade working environment reflection change characteristics is presented.The semi-physical simulation results show that the model has high accuracy.Based on the above research work,turbine blade temperature measurement method with working environment influence is proposed.The method has been applied to the existing multi-spectral data processing method,which fully considers high temperature gas radiation characteristics and high temperature background radiation reflection influence calculation,reduce the influence of operating environment of turbine blade in the process of temperature measurement and the precision of temperature measurement result is improved.Finally,in the process of measuring,the uncertainty of the temperature measurement system and the working environment are analyzed.