Design and performance investigation of a triple blade dual stage Savonius-alike hydrokinetic turbine from low flow stream reserves

ABSTRACTA trending technology that is being employed to generate hydro energy from low-flow stream reserves is the Savonius-alike hydrokinetic turbine (SAHT). Clearance between the stages of a dual-stage two-bladed SAHT was found to improve its performance at low flow speeds; however, the impact of clearance on the triple-bladed configuration of SAHT was not studied earlier. In this paper, a triple blade dual stage configuration of SAHT is designed, and its performance is investigated in a water flume under various stage clearances (0,5,10,15 and 20 mm), low flow speeds (0.45,0.55 and 0.65 m/s) and different brake loads. Detailed turbine performance under different design and off-design conditions are investigated to obtain meaningful performance insights. The findings show that torque production by the turbine increases with the increase of brake load, with maximum hydrodynamic torque generated at the highest brake load. The highest coefficient of performance and torque of 0.071 and 0.261 are obtained at a stage clearance of 5 mm, tip speed ratio of 0.273, and free-stream flow speed of 0.55 m/s. The present SAHT under design condition has improved performance compared to a dual blade dual stage SAHT exhibiting a wider tip speed ratio range for its application in low flow stream reserves. Further, this turbine may also be recommended for torque generation to work as a motor in a flow speed condition less than 0.5 m/s. The novelty of this work is the application of an additional flow control measure in the form of flow-through clearance to negotiate vertical water thrust through the clearance and exert additional pressure on the advancing blades of the SAHT in the upper stage.KEYWORDS: Savonius-alike hydrokinetic turbinebrake loadscoefficient of performanceflow speedstage clearance Disclosure statementNo potential conflict of interest was reported by the authors.Additional informationNotes on contributorsKanak Chandra SarmaMr. Kanak Chandra Sarma, Ph.D scholar of the National Institute of Technology, Silchar, Assam, India and Lecturer (Senior Scale) of Mechanical Engineering at the Silchar Polytechnic College, Assam, India. Mr. Sarma received his B.Tech. in Mechanical Engineering from Jorhat Engineering College , Assam and his M.Tech. from National Institute of technology, Silchar, Assam. Currently, he is Pursuing Ph.D. in Mechanical Engineering from National Institute of Technology, Silchar, Assam.Biswajit NathMr. Biswajit Nath, Ph.D scholar of the National Institute of Technology, Silchar, Assam, India. He received his B.Tech. in Mechanical Engineering from Anna University, Chennai, Tamil Nadu, India and his M.Tech. from Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India. Currently, he is Pursuing Ph.D. in Mechanical Engineering from National Institute of technology, Silchar, Assam.Agnimitra BiswasDr. Agnimitra Biswas did his B.E. in Mechanical Engineering from Regional Engineering College Silchar in 2001, M.Tech in Thermal Engineering from National Institute of Technology Silchar in 2007, and PhD in Mechanical Engineering from NIT Silchar in 2010. His research area was Vertical Axis Wind Turbines using experimental and computational methods. He has more than 16 years of teaching and research experiences. Presently he is working as an Associate Professor in ME Department, NIT Silchar since July 2022.Rahul Dev MisraDr. Rahul Dev Misra has got his B.E. (Mechanical Engineering) from Jorhat Engg. College under Dibrugarh University in 1991. He did his M.Tech in the specialization of Energy Studies from IIT Delhi in 1996. He has got the Ph.D. degree from IIT Roorkee in 2004. Dr. Misra has joined the Department of Mechanical Engineering of National Institute of Technology (formerly, Regional Engineering College) Silchar in 1992 as Lecturer. Presently he is serving as Professor (HAG) in the same department.