Wind parks constitute a concentrated way of exploiting wind energy affected to a considerable extend by wake effects. As a consequence, wind turbines operating in clusters will have reduced power output and lifetime.


To investigate the impact of wake effects to the design and performance of wind parks

To develop methods for better designing wind parks

Work carried out

A multi-level research activity has been conducted along the following guidelines:

Simulation of the flow characteristics downstream the rotor disk by means of advanced numerical models

Rotor region: A free wake vortex model is used to provide the velocity field and estimate the added turbulence just downstream the rotor plane.

Near-wake region: A Navier-Stokes solver using the k-å turbulence model gives the velocity field and the turbulence characteristics of the flow over the mixing region of the wake. Input to this are the results of the rotor region.

Far-wake region: A multi-parametric far-wake model based on similarity assumptions is filled so as to get the inflow information further downstream.

Investigation of the wake interaction among two or several overlapping wakes

Based on the findings of the first step, a second order energy scheme was devised for estimating the velocity and turbulence intensity in a multiple wake.

Development and evaluation of an improved modular wind park performance analysis engineering tool for flat terrains

Investigation of the terrain effects to the performance of wind parks

Extensive wind tunnel tests provided the necessary insight regarding the development of the wake in non uniform ambient flow. Next, explicit expressions for the velocity and turbulence characteristics in the wake were devised based on the curved wake concept.

Development of a method for the aerodynamically optimal design of wind parks

Research products

WINPPAN : WINd Park Performance Analysis code

It calculates the annual energy output, the individual machine output and the turbulence intensity to every wind turbine of a wind park with respect to the wind rose of the site.

WPDESI : Wind Park DESIgn code

It provides the optimal lay-out of a wind park installed in a specific site for producing maximum annual energy.