This brief provides a comprehensive introduction on the flow-induced instabilities (e.g., the pressure fluctuations and the vibrations) of the reversible pump turbines (RPTs) in the pumped hydro energy storage power stations (PHSEPSs) in China based on long-term field tests. The pressure fluctuations and the vibrations of several RPTs in China under different operational conditions are analysed in detail to reveal their generation mechanisms and propagation characteristics. The book presents advanced signal analysis and processing methods which are used for obtaining the time-frequency information and for finding the internal correlations between several types of signals. Advanced artificial intelligence algorithms are adopted for understanding the effective fault diagnosis and the identification of different flow patterns. The book overviews the fundamentals of the RPTs and the signal analysis methods, while it demonstrates that the analysis results of the pressure fluctuation and vibration data may be employed for the calibration of numerical simulations and the comparisons of model tests. It is primarily targeted to researchers and engineers working on the fields of condition monitoring and fault diagnosis of hydraulic machineries.

Flexibility and energy storage seem to be the main challenges of the energy industry at the present time. Pumped Storage Power Plants (PSP), using reversible pump-turbines, are among the most cost-efficient solutions to answer these needs. To provide a rapid adjustment to the electrical grid, pump-turbines are subjects of quick switching between pumping and generating modes and to extended operation under off-design conditions. To maintain the stability of the grid, the continuous operating area of reversible pumpturbines must be free of hydraulic instabilities. Two main sources of pumping mode instabilities are the presence of the cavitation and the rotating stall, both occurring at the part load. Presence of cavitation can lead into vibrations, loss of performance and sometimes erosion. Moreover, due to rotating stall that can be observed as periodic occurrence and decay of recirculation zones in the distributor regions, the machine can be exposed to uncontrollable shift between the operating points with the significant discharge modification and the drop of the efficiency. Both phenomena are very complex, three-dimensional and demanding for the investigation. Especially rotating stall in the pump-turbines is poorly addressed in the literature. First objective of the presented PhD study has been to develop the cost-efficient numerical methodology in order to enable the accurate prediction and analysis of the off-design part load phenomena. The investigations have been made on the reduce-scaled high head pump-turbine design (nq = 27) provided by Alstom Hydro. Steady and unsteady numerical calculations have been performed using code FINE/TurboTM with barotropic cavitation model implemented and developed before in the laboratory. Some of the numerical results have been compared to the experimental data. Cavitating flow analysis has been made for various flow rates and wide range of cavitation levels. Flow investigation has been focused on the cavitation influence on the flow behavior and on the performance of the machine. Main analyses include incipient cavitation values, head drop curves and cavitation forms prediction for wide ranges of flow rates and NPSH values. Special attention has been put on the interaction between cavitation forms and the performance drop (hump zone) caused by the rotating stall. Cavitation results showed good agreement with the provided experimental data. Second part of the thesis has been focused on the prediction and analysis of the rotating stall flow patterns. Computationally fast steady simulations have been presented and used to predict stable and unstable operating regions. The analyses have been done on 4 different guide vanes openings and 2 guide vanes geometries. In order to get detailed information about the unsteady flow patterns related to the rotating stall, more exact unsteady simulations have been performed. Local flow study has been done to describe in details the governing mechanisms of the rotating stall. The analyses enable the investigations of the rotating stall frequencies, number of stalled cells and the intensity of the rotating stall. Moreover, the unsteady calculations give very good prediction of the pumpturbine performance for both, stable and unstable operating regions. Numerical results v vi give very good qualitative and quantitative agreement with the available experimental data. The approach appears to be very reliable, robust and precise. Even though the numerical results (rotating stall frequencies, number of cells...) on the actual geometry should be confirmed experimentally, author believes that the methodology could be used on any other pump-turbine (or centrifugal pump) geometry. Moreover, the simulations can be used industrially to study the effects of the guide vanes geometries, guide vanes opening angles and influence of the gap between the impeller and the distributor in order to reduce or even eliminate the negative effects of the rotating stall.

Since the 1970’s, an increasing amount of specialized research has focused on the problems created by instability of internal flow in hydroelectric power plants. However, progress in this field is hampered by the interdisciplinary nature of the subject, between fluid mechanics, structural mechanics and hydraulic transients. Flow-induced Pulsation and Vibration in Hydroelectric Machinery provides a compact guidebook explaining the many different underlying physical mechanisms and their possible effects. Typical phenomena are described to assist in the proper diagnosis of problems and various key strategies for solution are compared and considered with support from practical experience and real-life examples. The link between state-of the-art CFD computation and notorious practical problems is discussed and quantitative data is provided on normal levels of vibration and pulsation so realistic limits can be set for future projects. Current projects are also addressed as the possibilities and limitations of reduced-scale model tests for prediction of prototype performance are explained. Engineers and project planners struggling with the practical problems will find Flow-induced Pulsation and Vibration in Hydroelectric Machinery to be a comprehensive and convenient reference covering key topics and ideas across a range of relevant disciplines.

Dieses aktuelle Referenzwerk behandelt numerische Optimierungsmethoden für Strömungsmaschinen und die wichtigsten industriellen Anwendungen. Grundlagen sind umfangreiche Forschung und Erfahrung der Autoren. Die logischen Zusammenhänge, um den Bereich der numerischen Strömungssimulation (CFD) zu verstehen, werden anhand der Grundlagen der Strömungsmechanik, von Strömungsmaschinen und ihrer Komponenten erläutert. Im Anschluss folgt eine Einführung in Methoden der Ein- und Mehrzieloptimierung, die automatische Optimierung, in Ersatzmodelle und Entwicklungsalgorithmen. Das Fachbuch schließt mit der ausführlichen Erklärung von Designansätzen und Anwendungen für Pumpen, Turbinen, Kompressoren und weiteren Systemen von Strömungsmaschinen. Der Nachdruck liegt hier bei Systemen für erneuerbare Energien. - Die Autoren sind führende Experten des Fachgebiets. - Ein handliches Fachbuch zu Optimierungsmethoden mittels numerischer Strömungssimulation bei Strömungsmaschinen. - Beschreibt wichtige Anwendungsbereiche in der Industrie und enthält Kapitel zu Systemen für erneuerbaren Energien. Design Optimization of Fluid Machinery ist ein wichtiger Leitfaden für Graduierte, Forscher und Ingenieure aus den Bereichen Strömungsmaschinen und zugehörige Optimierungsmethoden. Als Fachbuch mit allem Wissenswerten zu dem Thema richtet es sich an Studenten höherer Semester der Fachrichtungen Maschinenbau und verwandter Bereiche der Strömungssimulation und Luft-/Raumfahrttechnik.