Executive Summary : | Due to prevailing advantages such as predictable, sustainable, reliable energy source and affordable, the role of hydrokinetic energy source is very prominent to achieve sustainable devolvement goal -7 (SDG-7) of United Nation (UN). In hydrokinetic technology, only kinetic energy of flowing water stream without construction of dam is used to drive generator to produce electricity. Therefore, ‘hydrokinetic turbine’ is also named as Zero Head Hydro Turbine or In-stream Hydro Turbine. The type of blade profile (hydrofoil) has been considered as vital as it affects the operational effectiveness of hydrokinetic turbine. Apart from this, due to seasonal variation in the flow velocity in waterways such as river, canal etc., the variation in angle of attack for a hydrofoil will be very large to maintain power quality. As a result, flow separation (i.e. dynamic stall) may take place beyond a particular value of angle of attack, especially at low tip seed ratio (TSR) which limits performance of turbine. With the aim of improving the turbine performance even at higher angle of attack, different passive flow control (PFC) techniques have been used to control the flow over the surface of wind turbine blade which may delay or even eliminate the appearance of dynamic stall. So far, a very few PFC techniques such as leading-edge airfoil-slat, double blade hydrofoil have been used with Darrieus hydrokinetic turbine. The efficacy of other PFC techniques or combined effect of multiple PFC techniques is still unknown for hydrokinetic turbine. Hence, to bridge this gap, the aim of the present study is to investigate the efficacy of J-shaped hydrofoil on the performance of Darrieus hydrokinetic turbine. Further, an attempt will also be made to examine the performance of J-shaped hydrokinetic turbine with the vortex generators under different operating parameters such as Reynolds number, variation in free surface position. |