【作者】 周莹；

【导师】 黄志尧； 冀海峰；

【作者基本信息】 浙江大学 ， 控制工程， 2016， 硕士

【摘要】 近年来,随着小型工业设备的迅速发展,小通道气液两相流系统已成为两相流领域一个备受关注的研究热点。然而,目前小通道气液两相流在机理研究和工程应用方面仍然不够成熟,需进一步深入研究。参数检测技术的研究一直是小通道气液两相流领域的一个重要研究内容,现有的检测手段还难以满足小通道气液两相流机理研究和工程应用的诸多需求,因而进行小通道气液两相流参数测量的研究,具有重要的学术价值和广阔的应用前景。本学位论文将小通道气液两相流系统作为研究对象,利用光学检测方法对水平通道内的泡状流和段塞流进行了相关参数测量的研究工作。本文主要创新点和工作内容如下：1.设计并搭建了基于光电池阵列的小通道气液两相流参数测量系统,研制了12×6阵列式的光电池传感器,并选用激光二极管作为激光源。在内径分别为1.08mm、2.16mm、3.22mm和4.04mm的水平小通道下,进行了气液两相流的实验研究,并对实验获得的光电池阵列电压信号进行了时域和频域特征的分析。2.提出了一种基于光电池阵列的小通道气液两相流泡状流和段塞流截面参数测量方法。该方法首先利用光电池阵列采集反映小通道内部气泡／气弹截面信息的光强分布信号,然后采用主成分分析(PCA)和支持向量机(SVM)方法分别建立了气泡／气弹截面直径和截面中心点位置测量模型,最终实现泡状流和段塞流截面参数的测量。实验结果表明,该方法是有效的,在四种不同内径的水平小通道下气泡／气弹中部截面直径和截面中心点位置的测量相对误差均在10%以内。3.提出了一种基于气泡／气弹截面直径的泡状流和段塞流体积相含率测量方法。该方法首先利用所获得的气泡／气弹截面直径求得泡状流和段塞流的截面空隙率,进而运用积分累加的思想求取泡状流和段塞流的体积相含率,最后采用最小二乘法分别建立泡状流和段塞流体积相含率测量模型。四种不同内径的水平小通道内的实验结果表明,提出的方法是可行的,建立的模型是有效的,泡状流和段塞流体积相含率测量的最大绝对误差均小于10%。本学位论文的研究验证了利用所设计的基于光电池阵列的小通道气液两相流参数测量系统进行参数检测的可行性,利用光强分布信号实现截面参数的测量,为小通道气液两相流参数检测提供了一种新途径。同时,该系统采用激光二极管作为激光源,具有成本低、功率稳定、可靠性强等优点。更多还原

【Abstract】 In recent years, with the rapid development of the miniature industrial equipment, gas-liquid two-phase flow system in small channel has become an attractive research focus. However, the present study on the two-phase flow in small channel is still immature theoretically and practically, and needs to be further investigated. Study on parameter measurement technique is always an important research area in small-channel gas-liquid two-phase flow field. However, the existing measurement methods are still difficult to meet the requirements of mechanism studies and industrial applications of small-channel gas-liquid two-phase flow. Therefore, research on parameter measurement of gas-liquid two-phase flow in small channel is of great important academic value and application prospect.This thesis aims to study the parameter measurement of gas-liquid two-phase flow system in small channel. Based on optical measurement technique, the bubble flow and the slug flow in horizontal small channel are investigated.Main innovations and works of this thesis are listed as follows:1. Based on a 12×6 photodiode array sensor and a laser diode, a parameter measurement system of gas-liquid two-phase flow in small channel is designed and established. The experiments are carried out in horizontal small channels with inner diameter of 1.08mm,2.16mm,3.22mm and 4.04mm, respectively. And, the voltage signals obtained by the photodiode array are analyzed in both time domain and frequency domain.2. Based on a photodiode array, a cross-sectional parameter measurement method for the bubble flow and the slug flow in small channel is proposed. Firstly, the voltage signals, which reflect the cross-sectional information of the bubbles/slugs in small channel gas-liquid two-phase flow, are acquired by the photodiode array sensor. Then, Principal Component Analysis (PCA) and Support Vector Machine (SVM) technique are applied to develop the measurement models of the cross-sectional diameter and the cross-sectional center position of bubbles/slugs, respectively. Finally, the measurements of the cross-sectional diameter and the cross-sectional center position of bubbles/slugs are implemented. The experimental results show that the proposed method is effective and the relative errors of the cross-sectional diameter and the cross-sectional center position of the middle part of bubble/slug are both less than 10% in four small channels with different inner diameters.3. Based on the obtained cross-sectional diameter of bubbles/slugs, a void fraction measurement method for the bubble flow and the slug flow in small channel is proposed. The cross-sectional voidages of bubble flow and slug flow are calculated by using the cross-sectional diameters of bubbles/slugs. The volume void fraction is calculated by integral accumulation of the obtained cross-sectional voidages. The volume void fraction measurement models for bubble flow and slug flow are developed by Least Squares (LS) method. The experimental results in four small channels with different inner diameters indicate that the proposed method is feasible and the established model is effective. The maximum absolute errors are all less than 10%.This thesis verifies the feasibility of the proposed parameter measurement method based on photodiode array. The cross-sectional parameters are measured by the voltage signals, which can provide a new approach for parameter measurement of gas-liquid two-phase flow in small channel. Meanwhile, this system uses low-cost laser diode as a competent replacement of the expensive standard laser source and has the advantages of low cost, stable power and higher reliability.更多还原