Research On Transient Temperature Field Test System Based On High-speed Imaging Technology

Studying the temperature of the fireball produced when the ammunition explodes is of great significance for measuring the damage effectiveness of the ammunition.Usually,the temperature field is measured by a high temperature thermocouple or an infrared thermal camera.However,the transient temperature field has a short duration,dramatic temperature changes,and high temperature peaks,the low time resolution of the infrared thermal camera and the long response time of the thermocouple make it difficult for the two to meet the measurement requirements of the transient temperature field,at the same time,the generation of such temperature fields is generally accompanied by a strong energy release process.The test environment is complex,and it is easy to cause damage to contact temperature measurement systems such as high temperature thermocouples,the ability to repeat measurements is relatively poor.The high-speed imaging technology has the advantages of high time resolution and long-distance non-contact measurement,it is suitable for obtaining temperature data of transient temperature field,and the method of obtaining temperature based on image has the characteristics of high temperature measurement limit,therefore,this paper has carried out a research on the transient temperature field test system based on high-speed imaging technology,and provides a suitable measurement system for the study of transient temperature field characteristics.Based on the analysis of the explosive temperature field characteristics of common explosives such as TNT and fuel-air explosives,and based on the basic theory of radiation temperature measurement,the temperature measurement principle of the high-speed imaging system is expounded,then research on the method of establishing the system-related temperature model is carried out.Based on the principle of temperature measurement of highspeed imaging system,a theoretical model for conversion between digital image and temperature was established,and the calibration method of temperature measurement system based on high-speed imaging technology was studied,use the relevant data obtained by calibration and the theoretical model of temperature conversion,and use the least square method and RBF neural network to establish the actual temperature conversion model.Based on the characteristics of system long-distance measurement,a distance error correction method is proposed,and a distance correction model suitable for the test system is established.Based on the analysis of the test environment and the measured object,a transient temperature field test system based on high-speed imaging technology is designed.According to the system's requirements for temperature image preprocessing,A bilateral filtering method based on median is proposed,which can effectively suppress image noise and retain temperature field edge information;and An improved Otsu image segmentation method based on edge information is proposed;it can better extract effective temperature regions in the image.Developed test system software using Visual Studio and Open CV.The software includes image data reading module,image noise pre-processing module,image segmentation module and temperature field calculation and analysis module,it can realize the automatic pre-processing of the transient temperature field image,the temperature calculation of each pixel in the temperature field,the temperature distribution rendering display,and the temperature field data statistical analysis.The temperature of acetylene flame,incandescent tungsten wire,TNT explosion and fuelair explosives was measured by this system,and compared with the results of thermocouple and infrared thermometer test.Experiments show that the measurement deviation of this system and thermocouple when measuring the same acetylene flame temperature is about 6.47%;compared with the infrared thermometer,the system has an average deviation of 6.53% when measuring the same acetylene flame temperature,incandescent tungsten wire temperature,and TNT,temperature and pressure bomb transient temperature field;In addition,the uncertainty of the system is evaluated,and the expanded uncertainty is 7.32%,which verifies the accuracy and practicability of the system for measuring the transient temperature field.