微含气液体管道泄漏负压波试验研究

发布时间：2018-02-28 06:54

本文关键词： 微含气液体管道泄漏负压波传播特性衰减理论模拟仿真　出处：《中国石油大学(华东)》2015年硕士论文　论文类型：学位论文

【摘要】：本文基于气液两相流理论和瞬变流理论,采用试验研究、理论分析、数值模拟三种研究方法,对体积含气率低于2%的液体管道泄漏负压波的生成、传播及衰减规律进行研究,为负压波法在微含气液体管道的泄漏检测系统中的应用提供理论和技术基础。基于长度为375米、管径为DN25的304不锈钢管道,自行设计实验装置及数据采集系统,用MATLAB编制程序对采集的数据进行处理分析。利用实验系统进行了以下试验与模拟工作。(1)用透明管在首、中、尾三段处置换不锈钢管,观察到在体积含气率低于2%时气液混合物的流动状态及在流动过程中流型的演化规律,为负压波在微含气液体管道内的传播特性研究提供了支撑,并验证了影响流型的主要因素是含气率和气泡间碰撞机率。(2)测得了不同体积含气率下的压力波传播速度,并对已有的波速公式进行了修正,修正后的公式经验证与试验结果吻合良好;(3)验证了泄漏处向上游和下游传播的负压波大小相等,得出泄漏处负压波的大小与泄漏量之间的关系。(4)用机械波的衰减理论对负压波的衰减进行研究,测得试验数据满足衰减指数模型,通过数据拟合得出衰减指数α_1;计算出压力最大变化速率,发现其绝对值也满足指数衰减模型,求得衰减指数α_2;分别分析了α_1与α_2同体积含气率β之间的关系。(5)用均相流模型对负压波传播进行模拟仿真,采用特征线解法,摩阻项中采用拟稳态摩阻系数,得出的衰减模拟结果要低于试验值,通过添加附加摩阻项对拟稳态摩阻系数进行修正,可以得到与试验结果吻合良好的模拟结果。通过本文的研究工作,得出了负压波在微含气液体管道中的生成及传播特性,可以为基于负压波法的泄漏检测系统的灵敏度和泄漏定位精度的提高提供了理论和技术上的指导,对含有微量气体的液体管道泄漏的检测具有重要的意义。
[Abstract]:Based on the theory of gas-liquid two-phase flow and transient flow theory, the generation, propagation and attenuation of negative pressure wave in liquid pipeline with volume gas content less than 2% are studied by means of experimental study, theoretical analysis and numerical simulation. It provides a theoretical and technical basis for the application of the negative pressure wave method in the leak detection system of micro-gas liquid pipeline. Based on the 304 stainless steel pipeline with 375m length and DN25 diameter, the experimental device and data acquisition system are designed by ourselves. The MATLAB program is used to process and analyze the collected data. The following experimental and simulation work is carried out by using the experimental system. The transparent tube is replaced by the stainless steel tube at the first, middle and end sections. The flow state of the gas-liquid mixture and the evolution of the flow pattern in the flow process are observed when the volume gas holdup is less than 2, which provides the support for the study of the propagation characteristics of the negative pressure wave in the micro-gas-containing liquid pipeline. It is verified that the main factors affecting the flow pattern are gas holdup and collision probability between bubbles. The pressure wave propagation velocity under different volume gas holdup is measured, and the existing wave velocity formula is modified. The modified formula is in good agreement with the experimental results. It is verified that the negative pressure waves propagating upstream and downstream are equal in size. The relationship between the size of the negative pressure wave and the leakage volume is obtained. (4) the attenuation theory of mechanical wave is used to study the attenuation of negative pressure wave, and the experimental data satisfy the attenuation exponent model. The attenuation exponent 伪 -1 is obtained by data fitting, and the maximum change rate of pressure is calculated. It is found that its absolute value also satisfies the exponential attenuation model. The attenuation exponent 伪 _ 2 is obtained. The relationship between 伪 _ 1 and 伪 _ 2 with the same volume gas content 尾 is analyzed respectively. The homogeneous flow model is used to simulate the negative pressure wave propagation. The characteristic line method is used to solve the problem and the quasi-steady state friction coefficient is used in the friction term. The result of attenuation simulation is lower than the experimental value. By adding additional friction term to modify the quasi-steady state friction coefficient, the simulation results are in good agreement with the experimental results. The characteristics of negative pressure wave generation and propagation in micro-gas-containing liquid pipeline are obtained, which can provide theoretical and technical guidance for the improvement of sensitivity and leak location accuracy of leak detection system based on negative pressure wave method. It is of great significance to detect the leakage of liquid pipeline containing trace gas.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE973.6

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