CAJ | 학술논문

光学元器件随飞行器在大气中飞行时，其工作性能越来越多地受到大气悬浮汇聚微粒的影响。大气微粒在复杂流场中呈现何种运动汇聚效应，对于合理准确评估机载光学元器件的工作效能具有十分重要的工程意义，而复杂气动流场中微粒分布状态的预估一直是飞行器外界环境研究中的一个难点。气动问题的复杂性、大气中微粒的多样性一直是制约各种试验手段展开、数值模型建立的主要因素。利用先进的激光粒子图像技术，在风洞中对舵面旋涡主导的复杂流场中的微粒速度及分布特性进行了实验研究。在测量舵面翼梢脱落旋涡特性的基础上，通过激光片光扫描流场全域，同时高帧频CCD相机同步曝光，利用PIV 拍摄到的流场中涡流截面内微粒分布的瞬态图像。结合图像后处理技术，对原始粒子图像进行互相关、二值化处理，通过对图像区域内的灰度值计算，统计相对流场截面内的粒子浓度系数，得到在复杂旋涡结构流场内瞬态粒子的分布特性规律。研究结果表明，利用大气中微粒在激光片光下的米氏散射原理，可以有效地拍摄到复杂流场结构下粒子光学散射及分布的特性图像，解决了传统环境测试设备无法对复杂条件下流场内粒子分布进行实时测量的缺陷；在旋涡为主导的流场中，大气中的微粒由向心力牵引，在涡核周围达到平衡运动状态，微粒环绕涡核形成一条环状带，这一区域中的粒子浓度系数要远大于自由流场中的微粒，涡核中心粒子呈“空洞”状态。
광학원기건수비행기재대기중비행시，기공작성능월래월다지수도대기현부회취미립적영향。대기미립재복잡류장중정현하충운동회취효응，대우합리준학평고궤재광학원기건적공작효능구유십분중요적공정의의，이복잡기동류장중미립분포상태적예고일직시비행기외계배경연구중적일개난점。기동문제적복잡성、대기중미립적다양성일직시제약각충시험수단전개、수치모형건립적주요인소。이용선진적격광입자도상기술，재풍동중대타면선와주도적복잡류장중적미립속도급분포특성진행료실험연구。재측량타면익소탈락선와특성적기출상，통과격광편광소묘류장전역，동시고정빈CCD상궤동보폭광，이용PIV 박섭도적류장중와류절면내미립분포적순태도상。결합도상후처리기술，대원시입자도상진행호상관、이치화처리，통과대도상구역내적회도치계산，통계상대류장절면내적입자농도계수，득도재복잡선와결구류장내순태입자적분포특성규률。연구결과표명，이용대기중미립재격광편광하적미씨산사원리，가이유효지박섭도복잡류장결구하입자광학산사급분포적특성도상，해결료전통배경측시설비무법대복잡조건하류장내입자분포진행실시측량적결함；재선와위주도적류장중，대기중적미립유향심력견인，재와핵주위체도평형운동상태，미립배요와핵형성일조배상대，저일구역중적입자농도계수요원대우자유류장중적미립，와핵중심입자정“공동”상태。
The performance of optics instrument was more and more affected by aerosols while it was flying with the aircrafts in the atmosphere.It has a quite important significance on the evaluation of optics working efficiency on the aircrafts that the particulates moved and pooled in complex vortex flow field.While the estimate of particulates in the atmosphere coupled with complex vortex field is always one of the most important problems in the research of aircraft envi-ronment.The complexity of aerodynamics and the diversity of atmosphere are always the main factors to restrict both the development of experiments and the foundation of the numerical mod-el.The distributing and velocity characteristic of particulate in complex vortex flow field was re-searched for the first time by advanced PIV technology in the low speed wind tunnel.Through the measurement to the vortex after the rudder,the instantaneous picture of distributing particu-late in the flow field was captured by PIV technology.The laser light scaning the flow field and exposure synchronization were used in the experiment.The instantaneous regularities of distribu-tion of particulate in complex vortex flow field was finally acquired through the image post pro-cessing technology,cross-correlation processing and gray scale calculating on original particulate picture.The result shows that by the principle of Mie scattering through the particulates in the laser light,the picture about the instantaneous complex vortex and particulate distribution can be captured by CCD camera,and by this it solved the limitation that traditional measurement equip-ments can not get the information of distribution of particulate in complex vortex flow in real time. In the flow field dominated by vortex,the particulate in atmosphere was pulled by centrifugal force,moved to balance and finally pooled to a loop around the core of the vortex.In this area,the coeffi-cient of particulate density is much larger than it in the free flow,and in the center of the loop,there is few particulate in the core of the vortex.