The Research Of Emissivity Online Measurement System Based On Energy Method

Emissivity is one of the most important thermophysical parameters,which plays an important role in majority studies,such as the high or low emissivity of infrared coating materials,the physical characteristics of aircraft skin,the stealth of naval vessels and so on.The relative researches of emissivity measurement at home and abroad have a long history,but most of the researches are about the spectral emissivity of the material instead of total emissivity in a wavelength band,so that they can only be used in laboratory for precise measurements,not suitable for engineering application measurements.A small amount of the emissivity measurement devices for engineering application can only be achieved off-line measurement instead of online measurement of emissivity,that is,the object is in a static state.According to the investigations and researches,the practical application of emissivity measurement technology is urgently needed,and it is of great importance.Therefore,this thesis presents a new method for the on-line measurement of the normal emissivity.Based on the radiation energy laws,using independent blackbody method,an online measurement system is developed in this thesis with a bolometer infrared sensor as the core sensor,which has a wide response wavelength ranging from 2?m to 16?m and wide temperature ranging from 100? to 500?.This thesis describes the measuring principle of the system in detail,and establishes the relationship between the output response voltage of the system and the thermal radiation.And then,calculation formula of emissivity is derived step by step.At the same time,a new method to calculate the normal emissivity in a wavelength range is put forward,which provides a theoretical basis for the engineering application of the emissivity measurement.This thesis also introduces the designes of the measurement system,including mechanical design,electronic system design and information processing platform design,and analyzes the design principle of each part.In this thesis,the blackbody furnace is taken as the reference blackbody,and the system response of each temperature is tested,so that a complete database of reference blackbody is established.Then,taking the standard template and the equivalent blackbody as the measurement targets,the system is tested and verified,and the measurement meets the measurement accuracy requirements.Finally,the measurement system is applied to the engineering practice,and the results are in good agreement.The comprehensive test results show that the emissivity on-line measurement system developed in this thesis can meet the following requirements: the response wavelength is 2~16 m,the temperature range is 100~500?,and the measurement error is less than 0.05.