Frequency and vibration amplitude prediction of rotating discs subject to mode splitting

受模式分裂影响的旋转盘的频率和振幅预测

• 批准号: 508268-2017
• 负责人: Gosselin, Frederick
• 金额: $ 1.82万
• 依托单位: École Polytechnique de Montréal
• 依托单位国家: 加拿大
• 项目类别: Engage Grants Program
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=639534
• 关键词: Frequency; vibration; amplitude; prediction; rotating

Modern hydroelectric turbines are designed to achieve near perfect efficiency while keeping production costsas low as possible. One way to accomplish such a goal is by reducing the thickness of turbine blades,consequently lowering their stiffness and increasing their propensity to experience critical vibration levels.Moreover, the end-users' growing need for power regulation due to the integration of intermittent renewablesources leads to more frequent off-design operations as well as machine starts and stops, for which dynamicmechanical stresses are significantly higher than at best efficiency point. In this context, precise knowledge ofthe turbine dynamic characteristics, notably the variation of the natural frequencies of the rotor with rotationrate, is essential to avoid problematic vibrations. In many publications, pump-turbine runners have beenmodelled using a rotating disk submerged in water, highlighting the phenomenon of frequency split: a forwardand a backward travelling waves emerge as the disk rotate. This phenomenon is linked to the variation of addedmass with rotational velocity. The project has two main objectives: understand better the mechanism offrequency split; and develop a simplified simulation strategy to evaluate the natural frequencies of a rotatingdisk. Understanding the frequency split of pump-turbine runners and its underlying mechanisms is critical toevaluate the resulting stresses and the expected life of the machine. This project will provide an accurate andfast tool to improve the design of high head Francis turbines and pump-turbines. This tool is essential todevelop new reliable turbines and provide detailed information about the fatigue life of the equipment.

现代水轮机的设计目的是在保持尽可能低的生产成本的同时，实现近乎完美的效率。实现这一目标的一种方法是减少涡轮叶片的厚度，从而降低其刚度并增加其经历临界振动级别的倾向。此外，由于集成了间歇性可再生能源，最终用户对功率调节的需求日益增长，导致更频繁的非设计操作以及机器启动和停止，其动态机械应力明显高于最佳能效点。在这种情况下，准确了解涡轮的动态特性，特别是转子的固有频率随转速的变化，对于避免有问题的振动是至关重要的。在许多出版物中，用浸入水中的转盘模拟水泵水轮机转轮，突出了频率分裂的现象：随着转盘的旋转，出现前向行波和后向行波。这一现象与附加质量随转速的变化有关。该项目有两个主要目标：更好地了解频率分裂的机制；以及开发一种简化的模拟策略来评估旋转磁盘的固有频率。了解水泵-水轮机转轮的频率分裂及其基本机制对于评估由此产生的应力和机器的预期寿命至关重要。该项目将为改进高水头混流式水轮机和水泵水轮机的设计提供一个准确、快速的工具。该工具对于开发新的可靠涡轮机和提供有关设备疲劳寿命的详细信息至关重要。