激光干涉粒子成像及信息提取方法研究

发布时间：2018-12-13 10:28

【摘要】：随着国防工业及航空航天技术的迅猛发展,对高性能航空航天发动机提升其最大推力和推重比的需求日益迫切。其中,燃料雾化后的粒径大小及其分布对发动机的性能有着重要的影响。目前,激光干涉粒子成像技术作为一种能够更有效、实时地测量大范围、多分散性雾化场的测量方法,已成为雾化场粒子检测的最有效手段之一,其测量精度主要依赖于图像信息提取的准确度。激光干涉粒子成像技术将片状激光束照射粒子喷雾场,并用高速CCD相机在成像透镜的离焦面上采集粒子的散射光图像。粒子的0阶反射光和1阶折射光将在CCD相机上产生干涉条纹,通过对干涉图像的分析可实现对该粒子的尺寸测量。本文在现有激光干涉粒子成像测量方法的基础上,提出一种基于形态学-霍夫变换和傅里叶变换的粒子干涉图像处理算法,从粒子识别的角度改进信息提取的效果,以达到提高测量精度的目的;建立了激光干涉粒子成像测量光路模型,仿真分析了模型参数对激光干涉粒子成像测量结果的影响,验证了该信息提取算法的可行性,最后在标准粒子场和水喷雾场搭建粒径测量光路,进行实验验证。论文的主要研究内容如下:1.根据激光干涉粒子成像测量原理研究几何光学模型关键参数对测量结果的影响规律。利用Mie散射理论和Debye级数展开模型,计算粒子散射光的光强随散射角的振荡分布特性,探究粒子的散射光强与粒子直径的关系。对激光干涉粒子成像测量技术的光路模型进行分析,基于几何光学近似模型采用相位差法和杨氏干涉法推导该技术中粒径的计算公式。仿真分析入射光波长、散射角、折射率和收集角对测量结果的影响。2.对粒子场的干涉粒子图像进行粒子中心位置和频率信息提取。首先,提出基于形态学-霍夫变换的干涉条纹图识别算法和基于傅里叶变换的条纹频率提取算法,通过改进的粒子干涉条纹图识别算法来实现重叠粒子的准确识别,进而提高粒子测量精度;其次,利用两种算法对基本圆和干涉条纹进行仿真验证和分析,得到正确的中心坐标和条纹频率;最后,对不同浓度的粒子场中干涉粒子图像进行仿真验证,对视场中粒子数分别为10、30和50的粒子场均能完全识别。3.搭建激光干涉粒子成像测量光路,在散射角?(28)68.96°处对直径为24μm的聚苯乙烯标准粒子场进行粒子直径的测量,测量结果的绝对误差为0.4μm。利用CCD相机粒径测量法和激光干涉粒子成像测量方法对400μm离心式喷孔在不同压力下的雾化场进行测量实验,通过粒径分布和SMD值对测量结果进行评价。在三个不同压力值下,对同一位置分别采用这两种方法进行粒径测量,在同一压力值下,两种方法所得到的粒径分布整体一致,对应的SMD值的差值小于2.4μm。
[Abstract]:With the rapid development of national defense industry and aerospace technology, it is increasingly urgent to improve the maximum thrust and push-weight ratio of high-performance aerospace engines. The particle size and distribution after fuel atomization have an important effect on engine performance. At present, laser interference particle imaging is one of the most effective methods for particle detection in the atomization field, which can be used to measure the atomizing field in large range and in real time. The measurement accuracy mainly depends on the accuracy of image information extraction. Laser interferometric particle imaging technology irradiates the particle spray field with a flaky laser beam and collects the scattered light images of the particles on the defocus plane of the imaging lens with a high-speed CCD camera. The zero order reflected light and the first order refraction light of the particle will produce interference fringes on the CCD camera. The size of the particle can be measured by analyzing the interference image. In this paper, based on the existing laser interferometric particle imaging measurement methods, a particle interference image processing algorithm based on Morphology-Hough transform and Fourier transform is proposed to improve the effect of information extraction from the point of view of particle recognition. In order to achieve the purpose of improving the measurement accuracy; The optical path model of laser interference particle imaging measurement is established, and the influence of model parameters on the measurement results of laser interference particle imaging is simulated and analyzed, which verifies the feasibility of the information extraction algorithm. Finally, the light path of particle size measurement is built in standard particle field and water spray field, and the experimental results are verified. The main contents of this paper are as follows: 1. According to the principle of laser interferometric particle imaging, the influence of key parameters of geometric optical model on the measurement results is studied. Using the Mie scattering theory and the Debye series expansion model, the oscillatory distribution characteristics of the scattering light intensity with the scattering angle are calculated, and the relationship between the scattering light intensity and the particle diameter is investigated. The optical path model of laser interferometric particle imaging measurement technology is analyzed. Based on the geometric optical approximation model, the formula for calculating the particle size in this technique is derived by using the phase difference method and the Young's interferometry method. The influence of incident wavelength, scattering angle, refractive index and collecting angle on the measurement results is analyzed by simulation. 2. The information of particle center and frequency is extracted from the interference particle image of particle field. Firstly, an interferometric fringe pattern recognition algorithm based on Morphology-Hough transform and a fringe frequency extraction algorithm based on Fourier transform are proposed. The improved particle interference fringe pattern recognition algorithm is used to accurately identify overlapping particles. And then improve the precision of particle measurement; Secondly, two algorithms are used to verify and analyze the basic circle and interference fringes, and the correct center coordinates and fringe frequencies are obtained. Finally, the interference particle images of different concentrations of particles are simulated and verified. The particle fields with 1030 and 50 particles in the field can be fully recognized. A laser interferometric particle imaging measurement path was constructed to measure the particle diameter of polystyrene standard particle field with a diameter of 24 渭 m at the scattering angle of? (28) 68.96 掳. The absolute error of the measurement results was 0.4 渭 m. The particle size measurement method of CCD camera and the particle imaging method of laser interference were used to measure the atomization field of 400 渭 m centrifugal nozzle at different pressure. The measurement results were evaluated by particle size distribution and SMD value. Under three different pressure values, the two methods are used to measure the particle size at the same position. Under the same pressure, the particle size distribution obtained by the two methods is the same, and the difference of the corresponding SMD value is less than 2. 4 渭 m.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP391.41

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