The ducted design prevents using the polar plots available in the
literature, based on wind tunnel experiments, to estimate the
momentum source terms describing the rotor effects. Consequently,
relevant momentum source terms will be derived by
building beforehand upon a set of high-fidelity URANS simulations
for an isolated turbine. The aforementioned optimal speed, also
expressed as optimal tip speed ratio (TSR), ratio between the
rotational speed of the tip of the blades and the free-stream horizontal
velocity, is not known a priori since it depends on the local
flow conditions. Therefore, correctly assessing the power of a water
turbines array requires a parametric study on the combination of
TSR values for all the turbines belonging to the array. The present
work builds a simplified model to describe the behavior of a rotor
when working at its optimal TSR by using a procedure both global
and local to compute the source terms of the BEM model. Section 2
provides the main features of the HARVEST VAWT and reviews the
hydraulic operation of this turbine. Section 3 describes how the
performance of a VAWT can be accurately computed using a high-
fidelity URANS approach. Section 4 explains how a much cheaper
turbine modelling can be developed from a Blade Element
Momentum approach to account for the rotor description. The
proposed BEM-RANS approach is validated in Section 5 by comparison
with the reference URANS approach for an isolated turbine
and a row of turbines. Eventually, the efficient BEM-RANS model is
applied in Section 6 to analyze the global performance of a row of
turbines.