海底渗漏气体声波测量的气泡预处理与声源实验研究

发布时间：2019-06-04 00:14

【摘要】：国外使用声波方法测量海底天然气渗漏气体流量时,主要用反射波,这种方法适用于大流量的情况,对于气体流量小的情况需要采用透射波测量。本课题组的前期研究提出了用透射声波波形一振幅参数测量渗漏气泡流量,并开展了模拟实验研究,初步验证了这种测量方法的有效性,但还缺少反演气泡流量所必需的某些基础研究,比如气泡流量参数与透射超声波频率、声强等参数间关系。为得到准确的气泡流量测量结果提出了对气泡流的大小和空间分布情况进行调整,然后再进行上述测量,因此需要首先设计气泡预处理装置。此外,当运用声波方法对气体流量进行测量时,声波信号源需要能够输出两种基本波,正弦波和脉冲波,除此之外还要具有跳频波和脉冲串输出等功能。当前的通用信号源不能满足要求,需要设计新型声波信号源,用于海底天然气渗漏流量的测量。本文完成气泡预处理装置的设计,所设计的气泡预处理装置由多层结构重叠放置而成,利用气泡预处理装置内部结构达到对运动气泡破碎和均匀分布的目的。气泡预处理装置的每一层分为气泡切割、上导流、下导流三部分。气泡切割部分用于实现气泡碰撞破碎；下导流部分起到气泡收集作用,使气泡有正确运动方向；上导流部分用于矫正泡状流运动路径使其均匀的布满下一层下导流入口处空间。此外,设计了海底渗漏气泡预处理实验系统,包括海底渗漏气泡模拟装置、气泡破碎实验装置和数字图像采集装置等三大模块。并在所设计的实验系统上进行实验,在MATLAB平台对得到的大量统计数据进行分析处理后得出所设计的气泡预处理装置对气泡直径、气泡上升速度和气体容积含气率等重要参数的影响的几点结论,证明了所设计气泡预处理装置对海底渗漏气泡破碎和均匀的有效性。此外,所设计的声波信号源具备基本波、跳频波和脉冲串输出功能,输出波形精度和稳定度满足要求。本实验研究针对海底渗漏气泡声波测量时需要气泡大小合适、在测量通道内均匀分布这一要求,设计的气泡预处理装置达到要求。针对对声源的要求所设计的声波信号源工作稳定,利于透射波测量海底渗漏气体的流量。
[Abstract]:When the acoustic wave method is used to measure the leakage gas flow rate of natural gas in the seafloor, the reflected wave is mainly used in the abroad. This method is suitable for the case of large flow rate, and the transmission wave measurement is needed for the case of small gas flow rate. In the previous study of our research group, the transmission acoustic wave waveform amplitude parameter is proposed to measure the leakage bubble flow rate, and the simulation experiment is carried out to verify the effectiveness of this measurement method. However, there is still a lack of some basic research necessary for inversion of bubble flow, such as the relationship between bubble flow parameters and transmitted ultrasonic frequency, sound intensity and other parameters. In order to obtain accurate bubble flow measurement results, it is proposed to adjust the size and spatial distribution of bubble flow, and then to carry out the above measurement, so it is necessary to design bubble pretreatment device first. In addition, when the acoustic method is used to measure the gas flow rate, the acoustic signal source needs to be able to output two basic waves, sine wave and pulse wave, in addition to the functions of frequency hopping wave and pulse train output. The current general signal source can not meet the requirements, so it is necessary to design a new acoustic signal source for the measurement of seafloor natural gas leakage flow. In this paper, the design of bubble pretreatment device is completed, and the bubble preprocessing device is composed of multi-layer structure overlapping. The internal structure of bubble preprocessing device is used to achieve the purpose of broken and uniform distribution of moving bubbles. Each layer of bubble pretreatment device is divided into three parts: bubble cutting, upper diversion and lower diversion. The bubble cutting part is used to realize bubble collision and breakage; the lower diversion part plays the role of bubble collection so that the bubble moves in the correct direction; the upper diversion part is used to correct the bubble flow motion path so that it is evenly filled with the space at the entrance of the lower diversion. In addition, the experimental system of bottom leakage bubble preprocessing is designed, including three modules: bottom leakage bubble simulation device, bubble breakage experiment device and digital image acquisition device. The experiment is carried out on the designed experimental system, and a large number of statistical data obtained are analyzed and processed on the MATLAB platform, and the bubble diameter of the designed bubble preprocessing device is obtained. Some conclusions on the influence of important parameters, such as bubble rising velocity and gas volume gas content, prove the effectiveness of the designed bubble pretreatment device for bubble breakage and uniformity in seafloor leakage. In addition, the designed acoustic signal source has the functions of basic wave, frequency hopping wave and pulse train output, and the accuracy and stability of the output waveform meet the requirements. In order to meet the requirement of suitable bubble size in underwater leakage bubble acoustic wave measurement, the designed bubble pretreatment device meets the requirements of uniform distribution in the measurement channel. According to the requirements of sound source, the acoustic signal source is stable, which is helpful to measure the flow rate of leakage gas on the seafloor.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P733.2;P714.3

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