Research On Dual Band Infrared Online Temperature Measurement Technology

Turbine disk is the key part of aeroengine.It is very important to monitor the surface temperature of turbine disk in real time and stably for the performance evaluation of turbine disk and the warning of temperature exceeding standard.In order to solve the problem of turbine disk surface temperature measurement,the traditional temperature measurement method often adopts the contact temperature measurement method of surface welding thermocouple.However,thermocouples are easily separated from the surface of the turbine wheel due to its high speed rotation.This not only leads to a huge consumption of thermocouples,but also buries serious safety hazards in the measurement process.The development of non-contact infrared temperature measurement technology provides a new technical support for the surface temperature measurement of turbine wheel.The temperature measurement technology can effectively avoid the harm of direct contact,so it becomes a research hotspot in the field of turbine disk temperature measurement.Compared with other infrared temperature measurement technology,dual band radiation temperature measurement technology has more advantages in measuring weak radiation signal,which will also be the focus of this thesis.This thesis is devoted to the research on the technology of accurately measuring the surface temperature of turbine disk.Based on the theory of blackbody radiation and the concept of emissivity,the principle of dual band temperature measurement is deduced.In the processing of the measurement results of dual band method,a modified algorithm for emissivity ratio model is designed.In addition,the infrared radiation receiving model with angle factor is established,and the influence of angle factor on dual band temperature measurement is analyzed through the model.In this thesis,a dual band infrared radiation temperature measurement system is developed.In order to reduce the influence of the atmosphere on the output signal of the system,the experiment of the relationship between the atmospheric transmittance and the radiation signal was designed;in order to test the suppression performance of the system collimator to the background radiation,the experiment of the relationship between the oblique incidence background radiation and the output signal was carried out;in order to further test the temperature measurement effect of the system on the actual turbine disk surface,this thesis completed the temperature measurement test of three metal samples by building a simulation test bench,and divided the measurement data into training and test sets.After getting the emissivity ratio model through the training set,the test set is modified.In the field of on-line temperature measurement,this thesis also combines the first-order lag filter algorithm to suppress the instantaneous temperature mutation point in the process of temperature measurement.The final results show that the average absolute percentage error of the test set is less than 2% and the root mean square error is less than 10 ℃,which proves the validity of the modified algorithm and filter algorithm,and provides technical support for the field of dual band infrared online temperature measurement.