A two-scale blockage correction for an array of tidal turbines

Abstract

This work presents an analytical blockage correction for co-planar arrays of tidal turbines based on two-scale momentum theory. The study aims to address the issue of correcting blockage effects for arrays where constructive interference between turbines can significantly improve performance. The proposed analytical model is validated by correcting Reynolds-Averaged Navier-Stokes computations of turbine arrays across a range of realistic tip-to-tip spacings (local blockage) and channel widths (global blockage) to free-flow conditions, thereby demonstrating its validity and broad applicability. By comparing the proposed two-scale correction with a single turbine correction, the necessity of the model is highlighted. Additionally, an iterative method to apply the correction is presented. This novel correction method allows for the decoupling of local and global blockage effects, enabling the isolation and quantification of the local blockage effect observed in laboratory-scale experiments. The blockage correction will further allow for comparisons of performance between arrays , and allow for an improved understanding of how tidal turbine arrays perform in-situ.