Hydrodynamics of cavitating and vortical flows in hydraulic turbomachines in off-design conditions: inception and mitigation

非设计条件下液压涡轮机空化流和涡流的流体动力学：起始和缓解

• 批准号: RGPIN-2020-06177
• 负责人: Houde, Sebastien
• 金额: $ 1.68万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=718259
• 关键词: Hydrodynamics; cavitating; vortical; flows; hydraulic

The working principle of turbomachines, based on generating or extracting swirl, is a fertile ground for the development of vortices and flow instabilities. Those structures take the form of vortices, cavitating regions, and periodic flow separations. Examples are cavitating inter-blade channel vortices or rotating stalls. They generally induce pressure fluctuations that can either locally damage the runner or cause dangerous oscillations of the entire hydraulic circuit. Most of the time, those damaging flow phenomena occur in off-design conditions. The rationale for studying off-design conditions stems from the need to increase the operating range of hydraulic turbomachines to enable finer modulations of energy demands versus production. For hydraulic turbines, the introduction on electrical grids of large quantities of random energy sources such as solar and wind translates into more time spent in off-design conditions. Hence developing mitigation strategies of damaging flow structures in off-design operation will improve the reliability and efficiency of hydraulic turbomachines. Using experimental facilities and numerical tools of the Hydraulic Machine Laboratory of Laval University (LAMH), the research program “Hydrodynamics of cavitating and vortical flows in hydraulic turbomachines in off-design conditions: inception and mitigation” intends to study and develop mitigation strategies of damaging flow structures in hydraulic turbomachines based on parametrization of their inception mechanisms through measurements and simulations on reduced-scale models. The long-term objectives of the research program are to: Identify and parametrize inception mechanisms of damaging flow structures in turbomachines for off-design conditions using specialized reduced-scale models. Develop Reduced-Order Models representing the inception dynamics of those structures. Study and develop efficient mitigation strategies. The first five years of the program will focus on columnar vortex array in no-load conditions of hydraulic turbines and vortex-related cavitation surge present in hydraulic pumps and turbines. Studies will be initiated to identify the tools required to build the Reduced-Order Models of the columnar vortex array. Reduce-Order Models will eventually provide tools to improve flow analysis and develop efficient mitigation strategies. Scientific contributions from the short-term objectives will be detailed descriptions of the inception mechanism of the columnar vortex array, the evaluation of the mass flow gain factor and cavitation compliance for full-load cavitation surge and, novel analysis methods for industrial flows based on POD and DMD. Importantly, this proposal will lead to 15 new Highly Qualified Personel with training in active research domains such as deep learning, computer vision, advanced flow measurements, and analysis.

叶轮机械的工作原理是产生或提取涡流，是发展涡流和流动不稳定性的肥沃土壤。这些结构以漩涡、空化区和周期性流动分离的形式出现。例如空化、叶片间通道旋涡或旋转失速。它们通常会引起压力波动，可能会局部损坏转轮或导致整个液压回路的危险振荡。大多数情况下，这些破坏性流动现象发生在非设计条件下。 研究非设计条件的基本原理源于需要增加水力透平机械的工作范围，以实现对能源需求和生产的更精细的调制。对于水轮机，在电网中引入大量的随机能源，如太阳能和风能，意味着在非设计条件下花费更多的时间。因此，研究水力透平机械在变工况下破坏流动结构的缓解策略将提高水力透平机械的可靠性和效率。 利用拉瓦尔大学(LAMH)水力机械实验室(LAMH)的实验设备和数值工具，“非设计条件下水力透平机械中空化和涡流的流体动力学：开始和缓解”旨在研究和开发基于初始机理的参数化的水力透平机械损伤流动结构的缓解策略，通过缩尺模型的测量和模拟。 该研究计划的长期目标是： 使用专门的缩尺模型识别和参数化非设计条件下叶轮机械中损坏流动结构的初始机制。 开发代表这些结构的初始动力学的降阶模型。 研究和制定有效的缓解战略。 该计划的头五年将重点放在水轮机空载条件下的柱状涡阵列以及液压泵和水轮机中存在的与涡流相关的空化浪涌。将开始研究，以确定建立柱状涡旋阵列降阶模型所需的工具。降阶模型最终将提供改进流动分析和开发有效缓解策略的工具。 短期目标的科学贡献将是详细描述柱状涡阵列的形成机制，评估满载空化涌浪的质量流量增益系数和空化顺应性，以及基于POD和DMD的工业流动的新分析方法。重要的是，这项提议将导致15名新的高素质人员，他们在深度学习、计算机视觉、高级流动测量和分析等活跃的研究领域接受过培训。