International Journal of Offshore and Coastal Engineering Vol.6 | No. 2 | pp. 59 – 66 | November 2022 DOI:10.19026/ijoce.9.1369 ISSN: 2040-7459; e-ISSN: 2040-7467 © 2022 Department of Ocean Engineering – ITS Licensed under a Creative Commons Attribution 4.0 International License (URL: http://creativecommons.org/licenses/by/4.0/) 59 Submitted: July 7, 2022 | Revised: September 10, 2022 | Accepted: October 21, 2022 Hydrodynamic Performance Analysis of Vertical Axis Water Turbine (VAWT) Gorlov Type with Hydrofoil Thickness and Inclination Angle Variables using Computational Fluid Dynamics (CFD) Approaches Wisnu Wardhana a,* , Shade Rahmawati a , Dendy Satrio a , and Annisa A. Nurliana a a) Department of Ocean Engineering, Institut Teknologi Sepuluh Nopember, Kampus ITS – Sukolilo, Surabaya 60111, Indonesia *Corresponding author: wisnu@oe.its.ac.id ABSTRACT The issue of renewable and eco-friendly energy has become the focus of research in several countries to encourage eco-friendly alternative energy. One of them is by using turbines to produce electrical energy. Vertical Axis Water Turbine (VAWT) can be an exciting research object because it has various advantages. VAWT has a simpler structure, can move at relatively slow currents and is famous for its tendency to move regardless of the water flow directions. In this study, the experimental turbine from secondary data numerically simulates using the Computational Fluid Dynamics (CFD) method with the help of ANSYS V18.1 software. The Gorlov turbine model is manufactured in 3 dimensions under steady-state flow conditions. Validation is carried out after obtaining numerical results with the mean error rate being less than 10%. The variables in this research are the thickness of hydrofoil using NACA 0010, NACA 0016, NACA 0020, and variations in inclination angle of the blade for 25 0 and 60 0 . After comparing the simulation results in the form of torque values is done, it is shown that the best turbine performance is given by water turbine using NACA 0016 with 60 0 of inclination angle. Keywords: gorlov turbine, hydrofoil thickness, inclination angle, CFD, torque. 1. INTRODUCTION The increasing use of energy derived from fossil fuels and its increasingly limited availability in nature forces them to look for alternative energy sources. In Indonesia, there are still many areas that are lacking, and even electricity facilities are unavailable. Based on the data from the Ministry of Energy and Mineral Resources (ESDM) of August 2019, the national electrification ratio reached 98.86% [1]. The verification results of PT PLN (Persero), in 2019, around 1,103,859 households must be electrified. It is also stated that based on Bappenas data in 2014, 96% of electricity demand in Indonesia is still dominated by fossil fuels, namely oil, gas, and coal [2]. Meanwhile, the use of fossil fuels causes pollution, which has a destructive impact and is also difficult to renew. Alternative renewable energy solutions are options that are deemed appropriate and can be applied to solve the problem of cheap and equally distributed electricity. Indonesia has considerable renewable energy potential, especially as a maritime country, where the total area of the oceans reaches nearly 8 million km 2 but is still not optimally utilized. Indonesia can take advantage of the potential for energy that comes from the sea, namely ocean currents. One of them is by using turbines to produce electrical energy. Currently, the horizontal axis water turbine (HAWT) type water turbine has been widely made, used and developed, compared to the vertical axis water turbine (VAWT) type, because HAWT has a better efficiency value than VAWT in utilizing wind to become electricity. However, the VAWT type has several advantages over the HAWT type, including because of the characteristics of the VAWT, which has a simpler structure, can move at relatively slow currents, can receive current from all directions and can be combined with other architectural, structural concepts, it is also easy to install a gearbox, generator and bearing [3]. The advantages mentioned make VAWT a technology that does not require too much cost and is easy to implement, making it suitable to be developed for hydroelectric powerplant in remote and underdeveloped areas. The development of VAWT itself can also be applied as another alternative to reduce dependence on the supply of electrical energy originating from fossil resources. Research on VAWT itself actually started in the 1920s and began to be developed again in the 1970s when there was an oil embargo. One type of VAWT that is widely researched and developed is the Gorlov type which basically has a working principle which is more or less the same as the Darrieus type, utilizing lift force to rotate the rotor [4]. The foil of the Gorlov Helical Turbine (GHT) type is symmetrical and can rotate in both directions equally good enough. Several methods can be applied to obtain water turbine efficiency values. Computational Fluid Dynamics, commonly known as CFD, simulates the fluid phenomenon and its interaction with a water turbine. The CFD method became known around the 1970s with a working principle