基于破涡减阻思想的水力旋流器湍流相干结构与调控机制研究

At present, the cyclone separation technology is considered as the most feasible approach to gain a high efficiency separation of oil and water in oilfields. However, a low capacity of hydrocyclones caused by the high flow resistance can not meet the urgent needs of high water cut oilfields and deep-water oilfields. To address this problem, the applicant proposed a method of eddy breaking and drag reduction based on turbulent coherent structures in the strong rotational flow, which is expected to overcome the contradiction between flow resistance and separation efficiency of hydrocyclones. This project will carry out the following researches, aiming at the scientific problem of turbulent coherent structures and their control mechanism in hydrocyclones. Firstly, to clarify the coherent structures and their evolution processes, the wavelet analysis and the numerical eigenvalue decomposition method are used to analyze laser measurement data. With the data analysis, the formation mechanism of flow resistance in hydrocyclones would be clarified as well. Then, to reveal the key parameters of coherent structures influencing hydrocyclone performance, the effects of coherent structures on turbulent characteristics and time-averaged flow field will be investigated, and further a mathematic model of drag reduction ratio would be established. Finally, to reveal the controlling mechanism of coherent structures, the quantitative relationship between the key parameters of coherent structures and the structure of vortex sheet as well as the operating conditions of hydrocyclones will be constructed by data processing with machine learning algorithm. Moreover, experimental verification will be carried out. By combining these aspects of research, the project is expected to provide theoretical fundamentals for a development of hydrocyclones with low resistance and high efficiency and provide technical support for oilfield development.

目前旋流分离技术被认为是油田实现油水高效分离的最可行方式，但水力旋流器高流动阻力导致的低处理能力无法满足高含水油田现状和深水油田发展的迫切需求。针对上述难题，申请人提出了强旋转湍流基于相干结构的破涡减阻思想，可望解决水力旋流器流动阻力和分离效率相互制约的矛盾。本项目针对水力旋流器湍流相干结构及其调控机制这一科学问题，拟开展如下研究：基于激光测量数据，采用子波分析和数值特征分解法查明强旋转湍流的相干结构，分析演化过程，阐明旋流器流动阻力形成机制；查明相干结构控制对旋流器湍流特性和时均流场的影响规律，研究相干结构关键参数，构建减阻率模型；基于数值模拟数据库，采用机器学习法构建相干结构关键参数与破涡片结构和旋流器工况条件之间的量化关系，揭示基于破涡减阻思想的水力旋流器湍流相干结构的调控机制，并进行实验验证。本项目的研究成果可为低阻高效水力旋流器的研发提供理论指导，进而为油田开发提供技术支撑。

快速高效预分水是解决高含水油田瓶颈难题的关键，传统水力旋流分离设备很难满足处理能力的需求。本项目将湍流减阻原理应用于旋流分离过程提出了一种水力旋流器破涡减阻方法。利用PDA实验测量和CFD数值模拟建立了湍流特性识别方法，阐明了水力旋流器内湍流特性以及阻力产生过程，开展了时均流动和湍流脉动对不同调控方法的响应规律研究，明析了流场调控途径和减阻机制，并将研究成果应用于高含水油井采出液高效预分水过程，建立了低阻高效预分水设备的设计和调控方法。具体的创新性成果包括：1）建立了水力旋流分离器湍流特性分析的CFD数值模拟方法，揭示了流动阻力形成机制并针对流动减阻提出了流场调控方法，建立了低阻高效预分水设备系列化设计方法；2）研究成果成功应用于油田实际高含水油井采出液的中试试验，当含水率在80%~95%之间变化时，在保证分水率大于50%的前提下，水出口含油浓度可控制在1321.6 mg/L以下，满足各项指标要求。在本项目的资助下，共发表论文5篇，授权发明专利3项；培养硕士研究生4名。项目研究成果为水力旋流分离设备的减租降耗提供了理论和技术支撑，将推动高含水油井采出液处理工艺的发展，并丰富旋流分离理论，具有重要的意义。

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