Analysis of the aerodynamic performance of the multi-rotor concept

The Science of Making Torque from Wind 2014

Chasapogiannis, Petros^1 ; Prospathopoulos, John M.^1 ; Voutsinas, Spyros G.^1 ; Chaviaropoulos, Takis K.^2

National Technical University of Athens, Heroon Polytechniou 9, 15780 Zografou, Greece^1

Center Renewable Energy Sources, 19Km Leof. Marathonos, 19009 Pikermi, Greece^2

关键词: Aero-dynamic performance;    Blade geometry;    Downstream distances;    Offshore installations;    Rated condition;    Rotor systems;    Single actuators;    Tip speed ratio;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/524/1/012084/pdf
DOI  :  10.1088/1742-6596/524/1/012084

来源: IOP

【 摘 要 】

The concept of a large (∼20MW) multi-rotor wind turbine intended for offshore installations is analysed with respect to its aerodynamic performance. The effect of closely clustering rotors on a single actuator disk is estimated using two different modelling approaches: a CFD solver in which the rotors are simulated as distinct actuator disks and a vortex based solver in which the blade geometry is exactly considered. In the present work, a system of 7 rotors is simulated with a centre to centre spacing of 1.05D. At nominal conditions (tip speed ratio=9) both models predict an increase in power of ∼3% alongside with an increase in thrust of ∼1.5%. The analysis of the flow field indicates that in the 7 rotor system the individual wakes merge into one wake at ∼2D and that flow recovery starts at approximately the same downstream distance as in the single rotor case. As regards the dynamic implications of the close spacing of the rotors it was found that there is an increase in the loading amplitude ranging from 0.30-2.13% at blade level in rated conditions.