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重要资源。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，通过液化天然气（LNG）的开采、液化和出口就可以创造超过10万个就业岗位。天然气被认为是一种比汽油或柴油更环保的绿色交通工具，有几家加拿大公司已经成为天然气燃料汽车系统的市场领导者。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，需要一个研究项目，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存在空气动力学和相不稳定性，因此为天然气工业设计流体机械面临着重大挑战。气动不稳定性会导致气流从有序的层流状态向湍流状态转变，对设备效率产生重大影响。气动不稳定性还会引发液化天然气流动中的相不稳定性，导致空化，这是一种在流动中形成蒸汽气泡然后迅速破裂的过程，导致机器损坏。为了确保新型流体机械设计的安全性、可靠性和效率，工程师需要稳健、准确的模型来预测流体中不稳定性的发生和发展。目前的预测模型缺乏对流动中发生的物理过程的坚实基础，需要大量的调整，并且忽略了气动和相位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界提供急需的分析模型，能够预测流体机械向湍流和空化的过渡。研究方法将主要包括高保真数值模拟。计算流体动力学（CFD）将用于模拟流动过渡到湍流的气动不稳定模式。通过将实际流体特性和多相算法结合到模拟中，研究气动不稳定性和相不稳定性的相互作用。分析模型将在数值模拟提供的改进的物理理解的基础上发展，并将集成到现代计算工程软件中，以便工业快速采用。该研究项目将培养专门从事流体流动数值模拟的工程师，并对天然气行业的流体机械有广泛的了解，使他们成为加拿大经济快速增长领域的有力贡献者

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.**