Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman Performance investigation of self-adjusting blades turbine through experimental study Fatemeh Behrouzi a , Mehdi Nakisa b , Adi Maimun c, ⁎ , Yasser M. Ahmed a,d , Atef Salem Souf-Aljen a a Faculty of Mechanical Engineering, Universiti Teknologi Malaysia (UTM), 81310 Skudai, Johor, Malaysia b Department of Mechanical Engineering, Bushehr Branch, Islamic Azad University, Bushehr, Iran c Marine Technology Centre, Universiti Teknologi Malaysia (UTM), 81310 Skudai, Johor, Malaysia d Faculty of Engineering, Alexandria University, Egypt ARTICLE INFO Keywords: Experimental study Vertical axis current turbine Self-adjusting blades Arm ABSTRACT In the quest for renewable energy sources and sustainable development, hydrokinetic energy available in marine currents, river currents, water flows and man-made canals should be harnessed. This is particularly true for rural and remote areas, which have access to water but often have poor electricity. The vertical axis current turbine, which is a key hydrokinetic technology, has been greatly improved over the last few years. It has numerous advantages, including independency of flow direction, design simplicity, quiet operation, no required yaw mechanism and low cost. The Savonius hydrokinetic turbine is one of the most important drag-type config- urations of a vertical axis current turbine. However, it suffers from negative torque, negative drag force on the returning blades, low efficiency and difficulty interfacing with a generator. This paper proposes a novel drag- based vertical axis current turbine using arms and self-adjusting blades. This novel design was developed based on the framework of a Savonius hydrokinetic turbine. In an effort to decrease the hydrodynamic resistance of the returning blades and increase the total output torque of the turbine, this study aims to investigate the perfor- mance characteristics of a novel vertical axis current turbine (hereinafter referred to as “self-adjusting blade turbine”). Experimental tests were conducted in the Universiti Teknologi Malaysia (UTM) at low speed currents to assess the performance characteristics of three configurations of a fixed blade turbine and a self-adjusting blade turbine. The force acting on one blade of the self-adjusting turbine was analysed in detail. The results showed that the arm length and blade angle affected the performance of turbine, and that there was 30.7% increase in performance for the self-adjusting blade turbine compared to the fixed blade turbine. 1. Introduction Electricity is the fastest-growing final form of energy, such that the shortage of electrical energy would cause an economic and social crisis in many countries. According to the International Energy Agency (IEA) in 2017, 67% of world electricity generation was based on conventional energy sources, as shown in Fig. 1.1. Conventional energy contributes to global warming and environmental pollution; therefore, finding sustainable and clean energy sources has become an urgent necessity for researchers worldwide. Wind energy, solar energy, biomass, hydropower and thermal en- ergy are all renewable energy sources. Hydropower has attracted the most attention compared to other renewable energy sources, because it is high energy density, continuously available, predictable, independent of weather conditions and has less impact on environmental and human activity [2,3]. Hydrokinetic energy is a recently introduced type of hydropower which has huge potential to generate electricity from running water; i.e. from marine current, river current, man-made channels, irrigation ca- nals and industrial outflow. It can be deployed especially in areas re- mote from existing electricity grids, but with access to flowing water. Depending upon the alignment of the axis of rotation with respect to the water flow, hydrokinetic turbines can be classified into two categories: horizontal-axis turbines and vertical-axis turbines. In small-scale power generation, vertical axis turbines are preferred, due to the independency of flow direction, design simplicity, quieter operation, no requirement for a yaw mechanism and low cost [4–6]. Many studies have implemented technologies to improve the perfor- mance of the vertical axis turbine. Asim et al. [7] numerically in- vestigated the effect of different configurations of blades and stators on the performance of a marine current turbine. Curved stators generated 87% higher output compared to straight stators. A new blade shape was https://doi.org/10.1016/j.enconman.2018.11.066 Received 5 July 2018; Accepted 26 November 2018 ⁎ Corresponding author. E-mail address: Fatemeh.behrouzi2012@gmail.com (F. Behrouzi). Energy Conversion and Management 181 (2019) 178–188 0196-8904/ © 2018 Elsevier Ltd. All rights reserved. T