Comparative assessment of actuator-Line modeling of FOWT rotor aerodynamics to wind tunnel experiments

Abstract

The paper presents aerodynamic analyses of the scaled DTU 10MW laboratory model with surge and pitch platform motion in controlled environment applying an Actuator Line Method (ALM) to reproduce the experiments conducted in the large-scale Wind Tunnel of the Politecnico di Milano during UNAFLOW and OC6 Phase III test campaigns. The Effective Velocity Method (EVM) is implemented in the in-house ALM solver to sample the velocity at actuator points and determine the angle of attack. Fixed-bottom wind turbine URANS simulations reveal that thrust and torque deviations are within 3% and 5% respectively to experimental counterparts. Platform surge and pitch are simulated with ALM adopting a combination of motion frequencies and amplitudes finding a good agreement with experimental counterparts both in terms of loads and wake quantities. This paper also shows the capability of in-house ALM to model control strategies, imposing sinusoidal variation of blade collective pitch, which might generate dynamic inflow conditions. An in-depth cross comparison is conducted on FOWT wake quantities to investigate the flow behaviour and wake recovery induced by floating motion.