光场层析成像三维流场测量方法研究  

Light Field Tomographic Velocimetry for Measurement of Three-Dimensional Flow Field

作　　者：曹丽霞 许传龙[1] CAO Li-Xia;XU Chuan-Long(Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy andEnvironment, Southeast University, Nanjing 210096, China)

机构地区：[1]能源热转换及其过程测控教育部重点实验室(东南大学)能源与环境学院

出　　处：《工程热物理学报》2019年第7期1553-1561,共9页Journal of Engineering Thermophysics

基　　金：国家自然科学基金(No.51676044,No.51327803);江苏省自然科学基金杰出青年基金项目(No.BK20150023)

摘　　要：光场相机通过一次曝光能同时记录光场的辐射强度、位置及方向信息。本文利用单光场相机代替多相机系统记录三维流场图像,研究了一种基于光场成像理论的层析粒子图像测速(光场tomo-PIV)技术,用于三维流场3D-3C速度场的测量。在粒子场重建中,提出一种适用于光场相机的Multiplicative First Guess-Expectation Maximization(EM)层析重建技术。进行了数值模拟验证该算法的准确性。首先,利用光线追迹技术产生粒子的光场图像;然后利用MFG-MART反演光场图像重构出三维粒子场;最后,利用三维互相关技术计算3D-3C速度场分布,并对比分析了两种不同互相关窗口尺寸下的速度场精度。然后,搭建了基于单聚焦光场相机的tomo-PIV系统并开展了实验研究。数值模拟及实验结果表明所提出的方法能够用于3D-3C速度场的测量。The light field camera can record the radiation intensity,position and direction of the light field simultaneously in a single exposure.Thus,a single light field camera is used to record the image of the 3-dimensional(3 D)flow field instead of the multiple cameras system.In this study,a tomographic particle image velocimetry based on the light field imaging(light field tomo-PIV)is proposed to measure the three dimensional-three component(3 D-3 C)velocity.For the reconstruction of the tracer particle,a Multiplicative First Guess-Expectation Maximization(EM)based on the light field camera is presented to reconstruct the particle field in flow field.Numerical simulations are carried out to verify the accuracy of the proposed algorithm,a ray tracing technique is firstly used to produce the light field image of the tracer particle.Then,the reconstruction of 3 D particle field is achieved by the MFG-EM.A 3 D cross-correlation is finally used to calculate the 3 D-3 C velocity of flow field.The accuracy of the velocity at two different interrogation sizes is compared.Further a light field tomo-PIV based on a single focused light field camera is built and tested.Simulations and experiments verified the feasibility of the light field tomo-PIV for the measurement of the 3 D-3 C velocity in flow field.

关 键 词：流场 光场成像 粒子图像测速 层析重建 MFG-EM 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]