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发展的有希望的资源。根据2014年不列颠哥伦比亚省就业计划，仅通过液化天然气(LNG)的开采、液化和出口，就可以在不列颠哥伦比亚省创造超过10万个就业机会。在绿色交通方面，天然气已被确定为汽油或柴油的一种环境优势替代品，几家加拿大公司已经在天然气燃料汽车系统方面处于市场领先地位。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。*由于流经设备的流体中存在空气动力学和相态不稳定性，为天然气行业设计流体机械面临巨大挑战。气动不稳定性会引发流动从有序的层流状态向湍流状态的转变，这将显著影响设备的效率。空气动力不稳定性还会触发LNG流动中的相不稳定，导致空化，这是一个过程，在这个过程中，蒸汽气泡在流动中形成，然后迅速崩溃，对机器造成损害。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动中不稳定性的开始和发展。目前的预测模型在流动中发生的物理过程中缺乏坚实的基础，需要广泛的调整，并且忽略了空气动力学和相态不稳定性之间的相互作用。*拟议的研究计划旨在为加拿大工业提供急需的分析模型，能够预测流体机械中向湍流和空化的转变。研究方法将主要包括高保真数值模拟。计算流体动力学(CFD)将被用来模拟气流转变为湍流的气动不稳定模式。通过将真实的流体特性和多相算法结合到模拟中，将研究气动和相位不稳定性之间的相互作用。分析模型将在数值模拟提供的改进的物理理解的基础上开发，并将被集成到现代计算工程软件中，以便迅速为工业所采用。该研究计划将培训专门从事流体流动数值模拟并对天然气行业的流体机械有广泛了解的工程师，使他们成为这一加拿大经济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.**