摘要
有限投影条件下激光吸收光谱二维测量光路优化对燃烧场重建结果具有重要影响.针对基于Tikhonov正则化的病态投影方程组求解问题,提出了基于正则化参数矩阵的光路设计与二维重建方法.建立了基于Tikhonov正则化参数矩阵的光路设计目标函数,利用遗传算法获得最佳光路布置方式,通过匹配光路与正则化参数分布对测量区域内正则化权重进行调整以减小重建误差.采用7185.6 cm^–1波段H2O特征谱线并结合20条投影光路对10×10离散化测量区域内双峰高斯分布模型进行了重建,对5种光路布置方式重建结果进行了对比分析,结果表明基于Tikhonov正则化参数矩阵的光路布置方式重建结果最佳.光路数量越少, Tikhonov正则化参数矩阵作用效果越明显.开展了针对气液两相脉冲爆轰发动机外流场的模拟测量研究,验证了本文光路布置方式在复杂多变流场环境下重建效果.在实验室内针对小型燃气炉进行了实验测试,重建燃烧场峰值位置和幅值与实际情况吻合.研究结果对于推动激光吸收光谱二维重建技术在发动机诊断及燃烧效率提升方面的应用具有重要意义.
Beam arrangement with limited projections is a critical part of research on tunable diode laser absorption tomography reconstruction for combustion diagnosis.Based on the efforts to regularize this rank-deficient and ill-posed problem with Tikhonov regularization,a novel approach to using the regularization parameter matrix is developed for designing optical component layout and predicting the reconstruction accuracy.Objective function of beam arrangement is established by the rigorous mathematical derivation,and genetic algorithm is adopted to realize the optimization of function to overcome the difficulty associated with the multimodal nature of the problem.Nonuniform distribution properties of matrix elements in physical space relate to location and alignment of the laser/detector pairs,and form a basis for adjusting the weight between measurement and regularization to improve the reconstruction performance.A mathematical model of double Gauss distributions is established in a 10×10 element discrete tomography domain,and typically 20 measurement beams scanning the H2O transition at 7185.6 cm^–1 are available to probe the domain of interest.The systematic comparison between optimized beam array here and four existing beam arrangements in the literature is analyzed to validate the method.The reconstruction with Tikhonov regularization parameter matrix shows obvious advantages of reducing errors especially under the condition of fewer projections.The validation of reconstruction performance of the optimized beam array is also examined by simulating the laser absorption measurement which is carried out on phantoms generated using a simulation of external flow field of an airgasoline pulsed detonation engine.The result shows that the optimized beam array consistently outperforms other arrangements reported in complicated fluid field.A demonstration reconstruction experiment is performed on the distribution from small gas burners.Both locations and amplitudes are in good agreement with those in the actual case.Th
作者
李宁
Tu Xin
黄孝龙
翁春生
Li Ning;Tu Xin;Huang Xiao-Long;Weng Chun-Sheng(National Key Laboratory of Transient Physics,Nanjing University of Science and Technology,Nanjing 210094,China;Department of Electrical Engineering and Electronics,University of Liverpool,Liverpool L693GJ,UK)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2020年第22期368-378,共11页
Acta Physica Sinica
基金
中国国家留学基金(批准号:201906845059)
江苏省自然科学基金青年基金(批准号:BK20190439)
中央高校基本科研业务费专项资金(批准号:30919011258)资助的课题。
关键词
激光吸收光谱
二维重建
TIKHONOV正则化
奇异值分解
laser absorption spectroscopy
tomography reconstruction
Tikhonov regularization
singular value decomposition
