Performance analysis of dual-stage vertical axis hydrokinetic turbine (VAHT) with azimuth variation at open canal hydrokinetic power plant

For several decades, the use of hydropower generation using hydrokinetic turbines has grown rapidly, aiming to get energy alternatives and reduce the dependency on fossil energy. Despite it has low efficiency, the vertical axis hydrokinetic turbine (VAHT) has been used to utilize hydro energy and has a promising result. A previous study had stated that the utilization of cascaded blade enhances the performance of VAHT. However, this technology produces fluctuating torque and power during its rotation. Hence the dual-stage VAHT is proposed to overcome this issue to improve VAHT's efficiency. This research analyzes the dual-stage VAHT's performances by variating its inter-stage azimuth of 45°, 60°, 75°, and 90°. For each stage, there is six blades that attach at three arms. The computational fluid dynamics (CFD) simulation is employed as its capability to provide in-depth information regarding flow phenomenon, force, and torque. This simulation has proven that the dual-stage configuration has an impact on reducing torque fluctuation of VAHT and show that different of inter-stage azimuth angle brings to different torque fluctuation pattern. The average torque value produced by the new turbine with variations in shift between stages of 45°, 60°, 75° and 90° is 10,119.21 Nm, 10,656.13 Nm, 10,490.31 Nm, and 10,457.3 Nm, respectively.