Towards a General Analytical Model of Aerodynamic and Phase Instabilities in Advanced Fluid Machinery

天然气是加拿大经济增长和能源可持续性的一种有前途的资源。根据2014年不列颠哥伦比亚省就业计划，仅在不列颠哥伦比亚省就可以通过液化天然气（LNG）的开采、液化和出口创造超过10万个就业机会。天然气已被确定为绿色运输的汽油或柴油的环境上级替代品，并且几家加拿大公司已经成为天然气燃料车辆系统的市场领导者。为了加强加拿大在天然气开采和利用方面的世界领先地位，需要制定一项研究计划，重点是提高天然气系统中使用的泵、涡轮机和其他流体机械的效率和可靠性。 由于流过设备的流体存在空气动力学和相不稳定性，设计用于天然气工业的流体机械提出了重大挑战。空气动力学不稳定性可触发流动从有序层流状态转变为湍流，这显著影响设备效率。空气动力学不稳定性还可触发LNG流中的相不稳定性，从而导致气穴现象，在气穴现象中，蒸汽气泡在流中形成，然后迅速破裂，从而对机器造成损坏。为了确保新流体机械设计的安全性、可靠性和效率，工程师需要强大而准确的模型来预测流体不稳定性的发生和发展。目前的预测模型缺乏一个坚实的基础上发生的物理过程中的流动，需要广泛的调整，并忽略了空气动力学和相不稳定性之间的相互作用。 拟议的研究计划旨在提供加拿大工业急需的分析模型，能够预测过渡到湍流和流体机械中的气蚀。研究方法将主要包括高保真数值模拟。计算流体动力学（CFD）将用于模拟气流转变为湍流的空气动力学不稳定模式。通过将真实的流体性质和多相算法纳入模拟，将研究空气动力学和相不稳定性的相互作用。分析模型将在数值模拟提供的更好的物理理解的基础上开发，并将集成到现代计算工程软件中，供工业界快速采用。该研究计划将培养专门从事流体流动数值模拟的工程师，并对天然气工业中的流体机械有广泛的了解，使他们成为加拿大经济这一快速增长领域的强大贡献者。

Natural gas is a promising resource for Canada's economic growth and energy sustainability. According to the 2014 BC Jobs Plan, more than 100,000 jobs can be created in British Columbia alone through the extraction, liquefaction, and export of liquefied natural gas (LNG). Natural gas has been identified as an environmentally superior alternative to gasoline or diesel for green transportation, and several Canadian companies are already market leaders in systems for natural gas fueled vehicles. To strengthen Canada’s position as a world leader in the extraction and utilization of natural gas, a program of research is needed with a specific focus on improving the efficiency and reliability of the pumps, turbines, and other fluid machinery used in natural gas systems. Designing fluid machinery for the natural gas industry poses significant challenges due to the presence of aerodynamic and phase instabilities in the fluids flowing through the equipment. Aerodynamic instabilities can trigger transition of the flow from an orderly, laminar state to turbulence, which significantly affects equipment efficiency. Aerodynamic instabilities can also trigger phase instabilities in LNG flows resulting in cavitation, a process in which vapour bubbles form in the flow and then rapidly collapse, causing damage to the machine. To ensure the safety, reliability, and efficiency of new fluid machinery designs, engineers need robust and accurate models to predict the onset and growth of instabilities in the flow. Current predictive models lack a solid grounding in the physical processes occurring in the flow, require extensive tuning, and overlook the interaction between aerodynamic and phase instabilities. The proposed research program aims to provide Canadian industry much-needed analytical models capable of predicting transition to turbulence and cavitation in fluid machinery. The research methodology will consist primarily of high-fidelity numerical simulations. Computational fluid dynamics (CFD) will be used to simulate the aerodynamic instability modes by which a flow transitions to turbulence. The mutual interaction of aerodynamic and phase instabilities will be studied by incorporating realistic fluid properties and multiphase algorithms into the simulations. The analytical models will be developed on the basis of the improved physical understanding provided by the numerical simulations and will be integrated into modern computational engineering software for quick adoption by industry. The research program will train engineers who are specialized in numerical simulation of fluid flows and possess a broad understanding of fluid machinery in the natural gas industry, positioning them as strong contributors to this rapidly-growing area of Canada’s economy.