Journal of the Korean Society of Marine Engineering, Vol. 39, No. 8 pp. 856~862, 2015 ISSN 2234-7925 (Print) J. Korean Soc. of Marine Engineering (JKOSME) ISSN 2234-8352 (Online) http://dx.doi.org/10.5916/jkosme.2015.39.8.856 Original Paper This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Copyright ⓒ The Korean Society of Marine Engineering †Corresponding Author (ORCID: http://orcid.org/0000-0001-7316-1153): Department of Mechanical Engineering, Institute of New and Renewable Energy Technology Research, Mokpo National University, (61 Dorim-ri) 1666 Youngsan-Ro, Cheonggye-Myeon, Muan-Gun, Jeonnam, 58555, Korea, E-mail: ydchoi@mokpo.ac.kr, Tel: 061-450-2419 1 Department of Mechanical Engineering, Mokpo National University, E-mail: kimsj617@naver.com, Tel: 061-450-2419 2 Department of Mechanical Engineering, Mokpo National University, E-mail: pms72006@yahoo.com, Tel: 061-450-2419 Hydrofoil selection and design of a 50W class horizontal axis tidal current turbine model Seung-Jun Kim 1 ․ Patrick Mark Singh 2 ․ Young-Do Choi † (Received July 3, 2015； Revised September 2, 2015；Accepted September 20, 2015) Abstract: Tidal current energy is an important alternative energy resource among the various ocean energy resources available. The tidal currents in the South-Western sea of Korea can be utilized for the development of tidal current power generation. Tidal power generation can be beneficial for many fishing nurseries and nearby islands in the southwest region of Korea. Moreover, tidal power generation is necessary for promoting energy self-sufficient islands. As tidal currents are always avail- able, power generation is predictable; thus, tidal power is a reliable renewable energy resource. The selection of an appropriate hydrofoil is important for designing a tidal current turbine. This study concentrates on the selection and numerical analysis of four different hydrofoils (MNU26, NACA63421, DU91_W2_250, and DU93_W_210LM). Blade element momentum theory is used for configuring the design of a 50 W class turbine rotor blade. The optimized blade geometry is used for computational fluid dynamics (CFD) analysis with hexahedral numerical grids. Among the four blades, NACA63421 blade showed the max- imum power coefficient of 0.45 at a tip speed ratio of 6. CFD analysis is used to investigate the power coefficient, pressure coefficient, and streamline distribution of a 50 W class horizontal axis tidal current turbine for different hydrofoils. Keywords: Horizontal axis tidal current turbine, Hydrofoil, Blade element momentum theory, Power coefficient 1. Introduction Among the various ocean energy resources available, tidal current energy is an important alternative energy resource [1]. Tidal currents are reliable and predictable [2]; thus, it over- comes one of the major limitations of several natural re- sources, which is the lack of predictability. This lack of pre- dictability leads to periods where little or no energy is generated. In addition, tidal turbines have the potential of min- imizing both visual and noise pollution [3]. There are more than one thousand islands located in the southern region of Korea. The local government plans to de- velop the region for the local people, boost the tourism in- dustry, and build facilities for the processing of marine prod- ucts [4]. The increasing development in this region has led to the demand for cleaner energy resources and minimizing the utilization of diesel power plants. The introduction of tidal power generation will benefit many fishing nurseries and the entire region. Furthermore, tidal power generation can contrib- ute toward promoting energy self-sufficient islands. Small floating-bridge type tidal current turbines can be in- stalled in the limited space between small islands, instead of large tidal current turbines. The small tidal current turbines can be connected by bridge-type connection in order to in- crease the output energy, and this energy can be supplied di- rectly to nearby islands in the region. Figure 1 shows a sche- matic view of the proposed floating-type tidal current turbine. The floating-type tidal current turbine can be easily accessed for installation and maintenance. In this study, while developing a floating-bridge type 15kW class small horizontal axis tidal current turbine, as part of the research for the selection and the reduced model test of hydro- foil, a 50 W class horizontal axis tidal current turbine model de- sign is being studied. Blade design was carried out by using four different hydrofoils (MNU26, NACA63421, DU91_W2_250, DU93_W_210LM) to select the appropriate hydrofoil. Blade ele- ment momentum theory was used to configure the design of a 50 W turbine rotor blade [5]. The goal of this study is to com- pare results through computational fluid dynamics (CFD) analysis. CFD analysis was conducted to investigate the power coefficient, pressure coefficient, and streamline distribution.