Analysis of blockage correction methods for high-solidity hydrokinetic turbines: Experimental and numerical investigations

Abstract

Harnessing hydrokinetic energy from deep water to increase the operation periods of observing platforms has received considerable attention in recent years. High-solidity hydrokinetic turbines with reliable startup performance are suitable for deployment in deep water with low current speed. However, few studies have been reported on the blockage effect of water flume experiment of a high-solidity hydrokinetic turbine. Hence, three high-solidity hydrokinetic turbines with excellent self-starting ability, a ductless Archimedes screw hydrokinetic turbine, a Savonius turbine, and a high-solidity horizontal axis turbine, were numerically investigated under varying blockage ratio conditions. Eight common blockage correction methods were adopted and evaluated for the blockage correction of high-solidity hydrokinetic turbines. Recommended blockage correction methods and their corresponding error under different blockage ratios are summarized to provide a reference for future experiments. Results indicate that the operating state of the turbine will significantly affect the blockage correction factor. For drag-type hydrokinetic turbines with a low design tip speed ratio, the correction factor is the largest in the static state and generally exhibits a downward trend with the increase in rotational speed. Therefore, different correction methods should be used in diverse operating states of the turbine.