Performance analysis of multi-row vertical axis hydrokinetic turbine-straight blade cascaded (VAHT-SBC) turbines array

Due to its high energy concentration, hydrokinetic energy from tidal and rivers flow provides great expectation. One of the effective ways to meet the energy production target is to reduce the installation and maintenance effort by arranging turbines in such configuration, known as hydrokinetic turbine array. The performance of array configuration is affected by turbine position and rotational direction. Thus, research on this issue is needed to get a turbine array configuration design with optimum performance. This work provides a comprehensive analysis of the effect of turbine rotational direction and position on the array performance. To achieve this objective, the experimental study and URANS based CFD (Computational Fluid Dynamic) simulation were carried out. This study proposed 3 side-by-side configurations, and 2 multi-row configurations, i.e. 3T-A and 3T-B. The side-by-side configuration consists of Co-rotating (Co), counter-rotating-in (CtI) and counter-rotating-out (CtO). While the multi-row configuration consists of 3T-A and 3T-B. The comprehensive information is provided. Both experimental and numerical study confirmed that the velocity superposition in the interaction zone gives a constructive effect on turbine performance. Hence, all site-by-site configurations are able to enhance farm effectiveness approximately 30% at an incoming flow velocity of 1.3 m/s. However, Co configuration is recommended to be installed in the resource having unpredictable flow direction, since its performance is independent to the incoming flow direction. Meanwhile, the CtI is suitable for canal or river since it has better performance for unidirectional incoming flow. The study for multi-row configuration shows the effect of upstream turbines to the downstream turbine. The 3-TA configuration has better performance than 3T-B, because side-by-side configuration installation as the upstream turbine could compensate for the bad effect of upstream turbine wake.