Numerical simulation of foil with leading-edge tubercle for vertical-axis tidal-current turbine

Abstract

The main disadvantage of the vertical-axis turbine is its low coefficient of performance. The purpose of this work was to propose a method to improve this performance by investigating the hydrodynamic forces and the flow-field of a foil that was modified with a sinusoidal leading-edge tubercle. NACA 63(4)021 was chosen as the original foil since it has a symmetrical profile that is suitable for use on a vertical-axis tidal-current turbine. The study was conducted using a numerical simulation method with ANSYS-CFX Computational Fluid Dynamics (CFD) code to solve the incompressible Reynolds-Averaged Navier-Stokes (RANS) equations. Firstly, the simulation results of the original foil were validated with available experimental data. Secondly, the modified foils, with three configurations of tubercles, were modelled. From the simulation results, the tubercle foils, when compared with the original foil, had similar lift performances at low Angles of Attack (0-8 degrees of AoA), lower lift performances at medium AoA (8-19 degrees) and higher lift performances at high AoA (19-32 degrees). A tubercle foil with Height/Chord (H/C) of 0.05 can maintain the static stall condition until 32 degrees. Therefore, a vertical-axis turbine with tubercle-blades provides an opportunity to increase its performance by extending the operational range for extracting energy in the dynamic stall condition.

Performance Investigation of a Humpback Whale-Inspired Vertical Axis Current Turbine

“…However, in the present study, it appears to stall earlier when it reaches AoA 18°. In more detail, the same stall position is also possible in [35]. Meanwhile, the results from [32] and [36] only occur when the stall reaches AoA 20°.…”

“…However, in post-stall conditions, the more suitable drag coefficient occurs at the Reynolds number of 183,000. Referring to the differences that occur, especially in the studies of [36] and [35] the characteristics of the resulting coefficients are still acceptable even though there are slight differences in the experimental results. In general, simulations using QBlade produce good validation of the experiment, as described in [29].…”

Various Wavy Leading-Edge Protuberance on Oscillating Hydrofoil Power Performance

“…The interaction between the vortex pattern and the cavitation shedding dynamics was modeled by large eddy simulation (Kanfoudi et al 2017). There are many genus in the ocean that can serve as engineering inspiration and the humpback whale is one such species (Utama et al 2020). The morphology of humpback whales' pectoral flippers inspired the concept of looking into the effects of leading-edge protuberances on hydrofoil results (Fig.…”

In-Situ Experiment of Cross-Flow Savonius Hydrokinetic Turbine With a Deflector

“…One of the most popular crossflow type ocean current turbines is the Savonius. Over the years, research to investigate the Savonius ocean current turbine's performance has been carried out on experimentally [6], numerically using Computational Fluid Dynamics (CFD) methods [7], or both of them [8]. Results of this research according to the conditions of the study area.…”