On-line Emissivity Measuring System By Single-detector Ratio Method

At present, Emissivity measurement has important significance in real-time analysis onthe object of thermal radiation in the aerospace, the weapons and equipment, the industrialand agricultural production and some other fields. For example, it’s very important toanalyze the engine thermal radiation effects on peripheral body of the aircraft in order toensure its safety performance in the aircraft structure and strength design field, and thenaircraft airframe heat-resisting structure should be designed specially according to theeffects, or the heat radiation intensity of the engine surface should be changed accordingto the effects.Emissivity is a basilica parameter in the research of thermal radiation of theengine,but emissivity is influenced by many factors,so it is necessary to measure it on-line.There are many researchers engaged in the measurement of emissivity at home and abroad,and they have made considerable achievements in the laboratory, but on-line measurementtechnology of emissivity is still in its infancy.This thesis deeply researches the thermal radiation model of the hemisphere absorbingcover based on the thermal radiation energy method,and develops a on-line measuringsystem based on a new method called single detector ratio method according to the actualrequirement of the on-line measurement.This thesis introduces the error model analysisbased on the basic theory of single detector ratio method; then detailedly introducesoverall plan design, detector design, hardware circuit design, software design of themeasuring system; Finally,according to error model analysis of the measuring system, testequipment was designed. A lot of test for the measurement error model is done, and testverified error compensation model is correct, and the standard blocks and the blackbodyare used to calibrate the measuring system, and then this measuring system could be usedfor on-line measurement of a wide variety of object surface emissivity, the experimentalresults demonstrate that the measuring system can be applied for the long-time onlineemissivity measurement and obtain the accuracy of±0.05.The results of this study laid the foundation for the future of emissivity on-linemeasurement system.