Numerical Simulations of a Horizontal Axis Wind Turbine in Icing Conditions with and Without Electro-Thermal Ice Protection System

In this work, a preliminary design of an Electro-Thermal Ice Protection System (IPS) is performed on the NREL 5 MW reference wind turbine. A 3-hour rime icing event is simulated numerically with and without the IPS. The IPS is designed considering a uniform heat flux in the stream-wise and span-wise directions. Two protected regions are considered in the span-wise direction, covering the outer half and the outer third of the blade, respectively. Moreover, different power consumptions are compared, keeping the blade clean or leading to run-back ice formations. The aerodynamic coefficients of each blade section are computed to compare the effect of the different ice shapes at various angles of attack with the reference solution, i.e., the clean blade. The resulting power curves are compared with the clean blade to quantify power and energy losses. Results show that run-back ice can cause worse performance with respect to the ice accretion occurring without IPS. During ice accretion, the energy loss resulting from this simplified IPS design is higher than the one caused by the ice accretion without IPS. However, if the time frame following ice accretion is considered, considerably higher energy savings are obtained when at least the outer third of the blade is kept clean.