水力机械.混流式水轮机压力波动换位

[中文适用范围]： IEC 62882技术规范提供了用于弗朗西斯水轮机和泵-水轮机作为水轮机运行时的压力波动转换方法，包括：压力波动的描述、引起它们的现象及相关问题；本文件涵盖的现象特征，包括但不限于叶片间涡流、尾水管涡绳和转子-定子相互作用；证明运行条件和托马数（空化条件）是影响压力波动的主要参数；推荐测量和分析压力波动的方法；识别试验台和原型中的潜在共振；识别将测量结果从模型转换到原型的方法，或提供基于统计或经验预测原型中压力波动的方法；推荐数据采集系统，包括模型和原型传感器的类型和安装位置，并定义模型和原型之间的相似条件；展示比较模型水轮机和相应原型的压力波动测量；讨论用于从模型到原型转换的参数，例如在97%置信区间内的峰峰值、时域中的RMS值或标准差，以及通过FFT获得的主频率与旋转频率的关系；讨论从模型到原型的压力波动转换的不确定性；讨论影响转换的因素，包括那些无法在模型试验台上模拟的因素，如水道系统和机械系统；建立不同类型压力波动的转换方法；提出可能的减轻压力波动的方法；定义本规范的局限性。本文件仅限于正常运行条件。与冯·卡门涡流、瞬态、失控速度和空载速度相关的水力稳定性现象不在本文件范围内。本文件提供了识别模型试验台和原型水轮机中潜在共振的方法。本文件不处理共振条件的放大。当存在共振时，本文件中确定的转换方法不适用。在这些条件下，无法确定模型和原型压力波动之间的关系。本文件既不涉及机器的结构细节，也不涉及其部件的机械特性，只要这些特性不影响模型压力波动或模型与原型压力波动之间的关系。 [外文原描述]： IEC/TS 62882:2020(E) which is a Technical Specification, provides pressure fluctuation transposition methods for Francis turbines and pump-turbines operating as turbines, including: - description of pressure fluctuations, the phenomena causing them and the related problems; - characterization of the phenomena covered by this document, including but not limited to inter-blade vortices, draft tube vortices rope and rotor-stator interaction; - demonstration that both operating conditions and Thoma numbers (cavitation conditions) are primary parameters influencing pressure fluctuations; - recommendation of ways to measure and analyse pressure fluctuations; - identification of potential resonances in test rigs and prototypes; - identification of methods, to transpose the measurement results from model to prototype or provide ways to predict pressure fluctuations in prototypes based on statistics or experience; - recommendation of a data acquisition system, including the type and mounting position of model and prototype transducers and to define the similitude condition between model and prototype; - presentation of pressure fluctuation measurements comparing the model turbine and the corresponding prototype; - discussion of parameters used for the transposition from model to prototype, for example, the peak to peak value at 97 % confidence interval, the RMS value or the standard deviation in the time domain and the relation of main frequency and the rotational frequency in the frequency domain obtained by FFT; - discussion of the uncertainty of the pressure fluctuation transposition from model to prototype; - discussion of factors which influence the transposition, including those which cannot be simulated on the model test rig such as waterway system and mechanical system; - establishment of the transposition methods for different types of pressure fluctuations; - suggestion of possible methods for mitigating pressure fluctuation; - definition of the limitations of the specification. This document is limited to normal operation conditions. Hydraulic stability phenomena related to von Karman vortices, transients, runaway speed and speed no load are excluded from this document. This document provides means to identify potential resonances in model test rigs and prototype turbines. Scaling-up resonance conditions are not treated in this document. When resonance exists, the transposition methods identified in this document do not apply. Under these conditions, the relationship between model and prototype pressure fluctuations cannot be determined. This document is concerned neither with the structural details of the machines nor the mechanical properties of their components, so long as these characteristics do not affect model pressure fluctuations or the relationship between model and prototype pressure fluctuations.