2014 한국유체기계학회 학술대회 발표 논문, 2014년 11월 26-28일, 부산 The KSFM Journal of Fluid Machinery: Vol. 18, No. 4, August, 2015, pp.36~42(Received 4 Dec. 2014; revised 10 Feb. 2015; accepted for publication 2 Mar. 2015) 36 한국유체기계학회 논문집: 제18권, 제4호, pp.36~42, 2015(논문접수일자: 2014.12.04. 논문수정일자: 2015.02.10, 심사완료일자: 2015.03.02) ◎ 논 문 ◎ Original Paper DOI: http://dx.doi.org/10.5293/kfma.2015.18.4.036 ISSN (Print): 2287-9706 Investigation into the Internal Flow Characteristics of a Pump-turbine Model Patrick Mark Singh * , Chengcheng Chen * , Zhenmu Chen * , Young-Do Choi ** † Key Words : Pump-turbine(펌프 터빈), Internal Flow(내부유동), Impeller(임펠러), Flow Velocity(유속), Static Pressure(정압) ABSTRACT This is a study about one of the most widely used hydro machinery all over the world - pump-turbine. The system has an impeller which pumps water to an upper reservoir during the night and the same impeller acts as a runner for turbine mode during the day for providing stable electrical power to the grid. The internal flow analysis is investigated in this study to help understand how the water passes through the passage of the vanes and blades, providing the designer with useful information on the behavior of recirculation flows which could reduce the efficiency of the pump-turbine. The 100 kW pump-turbine model has H = 32 m, Q = 0.336 m 3 /s and N = 1200 min -1 . For this study there are 7 blades, 19 stay vanes and 20 guide vanes. From this study, it was observed that this pump-turbine design showed very good internal flow characteristics with no flow separation and no recirculation flows in normal operation mode. 1. Introduction Hydropower is one of the oldest forms of extracting energy from nature for industrial applications. This is a study about one of the most widely used hydro machinery all over the world -pump-turbine. Pumped- torage installations provide the most efficient and practical means for storing large quantities of energy (1) . The system has an impeller which pumps water to an upper reservoir during the night and the same impeller acts as a runner for turbine mode during the day for providing stable electrical power to the grid. For achieving high efficiency in both modes, the blades of the impeller need to be modified to be suitable for both the pumping and turbine modes. To do this, there are many things that need to be considered for developing a good pump-turbine, such as performance, internal flow, reliability and cavitation analysis among the common ones. However, as these are very broad topics, this study only investigates the internal flow of the pump-turbine system. The internal flow analysis is investigated in this study to help understand how the water passes through the passage of the vanes and blades, providing the designer with useful information on the behavior of recirculation flows which could reduce the efficiency of the pump-turbine. This can help make modifications to improve the system efficiency. 2. Modeling and Numerical methods 2.1 Pump-turbine model The design model of the pump-turbine system can be seen in Fig. 1. The design method used is similar to * Graduate School, Department of Mechanical Engineering, Mokpo National University, Mokpo ** Department of Mechanical Engineering, Institute of New and Renewable Energy Technology Research, Mokpo National University, Mokpo † 교신저자(Corresponding Author), E-mail : ydchoi@mokpo.ac.kr