Fluid-structure interactions in pipeline systems

在各种工程系统中，管道通常用于输送流体。管道系统通常包括空腔，如管道网络中软管、阀座和侧支的内部波纹。穿过空腔开口形成的湍流分离流动可能与声波耦合，由此产生的共振压力振荡可能导致噪声、振动，并最终导致管道的疲劳失效。虽然声学耦合流动已经成为许多研究的主题，但对各种声学模式特有的激发机制的深入了解仍然是难以捉摸的。 拟议的五年研究计划将调查与全球声学模式和捕获声学模式相关的管道系统的声学响应的根本差异。这一新见解将被用来发展被动和主动控制流致振动(FIV)的方法，并建立用于模拟工程系统声响应的降阶模型。此外，在所提出的研究计划中，还将探索流致声激励在管道-空腔系统中的新应用，例如能量收集。 除了研究导致管道故障的流体-结构相互作用(FSI)外，拟议的研究计划还将研究危险气体云在管道泄漏附近的扩散预测。特别是，二氧化碳管道的危害评估是提高石油采收率(EOR)和碳捕获和封存(CCS)过程中必要和不可或缺的一部分。到目前为止，二氧化碳运输的安全方面还没有得到充分的研究。目前CCS的努力主要集中在捕获和储存设施上，而运输方面受到的关注相对较少。 2010年，加拿大的能源生产产生了高达253万吨二氧化碳当量的温室气体，占其总排放量的36%。通过二氧化碳封存减少温室气体排放是旨在大幅减少温室气体排放的有效战略的重要组成部分。拟议的研究计划将解决可能影响二氧化碳封存基础设施监管框架的重要安全问题。更好地了解这些问题对于公众接受自动减支技术至关重要。拟议的研究计划旨在调查和量化各种情况下高压管道泄漏附近的危险气体浓度范围(例如，接近地面和其他固体表面，有或没有横流，以及各种泄漏几何形状)。 建议的研究是一项实验和计算相结合的研究，并辅之以理论建模。流体流动将通过求解非定常雷诺平均Navier-Stokes(URANS)方程来模拟，并将针对选定的系统几何形状和流入条件采用大涡模拟(LES)方法。液滴和固体颗粒的形成将通过求解相应相的概率分布函数的方程来模拟。 数字粒子图像测速仪将用于物理实验中的速度场测量，其结果将为深入了解管道中声源(S)的结构和气体泄漏的动量传递过程提供帮助。为了量化3D流动效应，将实施层析版本的PIV。除了速度测量外，还将开发一种红外平面激光诱导荧光(IR PLIF)技术来测量二氧化碳的气相浓度。

Pipelines are commonly used for transporting fluids in a variety of engineering systems. Pipeline systems typically involve cavities, such as the internal corrugations of flexible pipes, valve seats and side branches in pipeline networks. Turbulent, separated flows that form across the cavity openings can couple with the acoustic waves, and the resulting resonant pressure oscillations can lead to noise, vibrations and ultimately fatigue failure of the pipeline. While acoustically-coupled flows have been the subject of many investigations, insight into the excitation mechanisms specific to various types of acoustic modes remains elusive. The proposed five-year research program will investigate the fundamental differences in the acoustic response of the pipeline systems associated with the global and the trapped acoustic modes. This new insight will be used to develop methods of passive and active control of the flow-induced vibrations (FIV) and to formulate reduced-order models for simulations of acoustic responses of engineering systems. Moreover, novel applications of the flow-induced acoustic excitation of pipeline-cavity systems, such as energy harvesting, will be explored in the course of the proposed research program. In addition to studying the fluid-structure interactions (FSI) leading to the pipeline failure, the proposed research program will also look into prediction of the dispersion of hazardous gas clouds in the vicinity of a leak from a pipeline. In particular, hazard assessment of CO2 pipelines is a necessary and integral part of the Enhanced Oil Recovery (EOR) and the Carbon Capture and Storage (CCS) processes. To date, safety aspects of CO2 transportation have not been adequately studied. Current efforts in CCS are largely focused on capture and storage facilities, while the transportation aspects received relatively little attention. Energy production in Canada was responsible for up to 253 Mt CO2 equivalent of greenhouse gases in 2010, representing 36% of its total emissions. Mitigating greenhouse gas emissions using CO2 sequestration is an important part of an efficient strategy aiming to significantly reduce greenhouse gas emissions. The proposed research program will address important safety issues that can impact the regulatory framework of a CO2 sequestration infrastructure. A better understanding of such issues is critical to public acceptance of sequestration technologies. The proposed research program aims to investigate and quantify the extent of hazardous gas concentrations in the vicinity of a leak from a high-pressure pipeline in a variety of scenarios (e.g. proximity to ground and other solid surfaces, with and without cross-flow, and various leak geometries). The proposed research is a combined experimental and computational investigation that is complemented by theoretical modeling. Fluid flow will be simulated by solving the unsteady Reynolds-averaged Navier-Stokes (URANS) equations, and a large eddy simulation (LES) approach will be employed for selected system geometries and inflow conditions. Formation of liquid droplets and solid particles will be modeled by solving an equation for the probability distribution function for the corresponding phase. Digital particle image velocimetry (PIV) will be used to measure velocity fields in physical experiments, and the results will provide insight into the structure of the acoustic source(s) in the pipeline and into the momentum transfer processes of the gas leaks. In order to quantify the 3D flow effects, a tomographic version of PIV will be implemented. In addition to velocity measurements, a technique of infrared planar laser-induced fluorescence (IR PLIF) will be developed to measure the concentration of the gaseous phase of the CO2.