A CFD approach for modeling the rime-ice accretion process on a horizontal-axis wind turbine

The main objective of this paper is to model the rime-ice accretion process on a horizontal-axis wind turbine (HAWT) operating under icing conditions. The model calculation procedure was divided into two stages. The first stage consists of computing the two-phase flow that is composed of air and water phases. The two-phase flow was solved using the Eulerian–Eulerian approach with the help of Fluent, a commercial CFD code. At the end of the calculations, it is possible to obtain the local volume fraction and local water incidence velocity, which can be used to estimate the local collision coefficient. In the second stage, the thickness of the newly accreted ice layer was calculated and the geometry so obtained was processed with an in-house smoothing algorithm. From the model simulation, it is possible to obtain the 3-D ice shape, as well as the ice load on the HAWT blade, which can then be used to analyze the performance of the HAWT under icing conditions, or to help develop a feasible de-icing solution. The important model input parameters include: air speed, median volume diameter (MVD) of water droplets, liquid water content (LWC) and air temperature. The turbine under consideration is a NREL VI turbine that rotates along its axis at a constant angular speed. In the flow domain, a rotating reference frame was defined to account for the angular movement of the wind turbine. The results reveal, among other things, ice geometry information that can otherwise hardly be obtained by on-site observations.