Low-Order Modelling of Blade-Induced Turbulence for RANS Actuator Disk Computations of Wind and Tidal Turbines

TL;DR

This paper introduces a low-order turbulence model for wind and tidal turbines that improves RANS simulations by accounting for blade-induced turbulence effects, validated against experimental wake data.

Contribution

A generic blade-induced turbulence model for RANS actuator disk simulations that incorporates correction functions for rotor tip vortex effects, enhancing predictive accuracy.

Findings

Model matches wake measurements of a wind turbine

Incorporates rotor tip vortex effects

Improves RANS turbine wake predictions

Abstract

Modelling of turbine blade-induced turbulence (BIT) is discussed within the framework of three-dimensional Reynolds-averaged Navier-Stokes (RANS) actuator disk computations. We first propose a generic (baseline) BIT model, which is applied only to the actuator disk surface, does not include any model coefficients (other than those used in the original RANS turbulence model) and is expected to be valid in the limiting case where BIT is fully isotropic and in energy equilibrium. The baseline model is then combined with correction functions applied to the region behind the disk to account for the effect of rotor tip vortices causing a mismatch of Reynolds shear stress between short- and long-time averaged flow fields. Results are compared with wake measurements of a two-bladed wind turbine model of Medici and Alfredsson [Wind Energy, Vol. 9, 2006, pp. 219-236] to demonstrate the capability of the new model.