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Yuekun Sun 1 and Zhigang Zuo 1 and Shuhong Liu 1 and Jintao Liu 2 and Yulin Wu 1
Academic Editor:Weidong Shi
1, State Key Laboratory of Hydroscience and Engineering, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China
2, Beijing Institute of Control Engineering, Beijing 100090, China
Received 6 December 2013; Accepted 25 December 2013; 11 February 2014
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
Pump storage power stations (PSPs) are experiencing rapid developments in recent years, in response to the increasing demand of power/frequency modulations. A number of technical problems arise in the operations of pump turbine, which is the most important hydraulic part of PSPs. Hydraulic instability of pump turbine is found as one of the most influential problems, which is mainly caused by strong pressure fluctuations [1]. This instability can affect the safe and stable operations of the units. For instance, start-up difficulties caused by hydraulic instability have been observed in Guangzhou, Shisanling, Yixing, Tianhuangping, and many other PSPs [2-4] in China. It is very important to study the characteristics of pressure fluctuations in the units and thus search for methods to reduce them.
Many researches have indicated that the pressure fluctuations in vaneless space of the pump turbine are stronger than those in the other positions, which are mainly caused by rotor stator interaction (RSI) [5]. The RSI phenomenon may be a combination of potential flow and viscous flow [6]. As a result of potential flow, the flow in guide vanes is periodically disturbed by rotating runner blades, which is one of the main sources of pressure fluctuations extending to the spiral casing and draft tube. The characteristics of this interaction are mainly affected by parameters of vaneless gap. The viscous flow mainly causes nonuniformity of the velocity field in the spiral casing and vaneless space. It can also cause flow separations and wakes in the whole flow domain [7].
The understanding of the mechanism of RSI and the resulting pressure fluctuations has been improved through extensive studies. For example, Sinha and Katz [8] used PIV measurements to analyze the effects of blades orientations, wakes,...