Ice Nonsimultaneous Failure, Bending and Floe Impact Modeling for Simulating Wind Turbine Dynamics Using FAST

Abstract

Many promising locations for developing offshore wind energy are in cold regions. This type of environment introduces one important technological challenge for offshore wind turbine design: the impact of floating surface ice. Recent developments to add an ice-loading module to the wind turbine computer-aided-engineering tool FAST are described in this paper. These efforts enable FAST, developed and maintained by the National Renewable Energy Laboratory, to simulate the impact of ice on offshore wind turbines. The ice-loading module includes different ice mechanics models that address various ice properties, failure modes, and ice-structure interaction mechanisms. In a previous OMAE symposium paper, models for quasi-static crushing, transient dynamic ice breakage, and random forcing for the ice module were described. In this paper, three new models are presented. One model evaluates the ice-loading effective pressure reduction caused by ice nonsimultaneous failure in discrete local zones across the contact area. The second model generates time-dependent ice forces on conical structures caused by bending failure. The third model is used to simulate large ice floe interaction with wind turbine support systems. This third model describes ice forces that are limited by momentum or splitting failure of ice floes. These models are integrated in the FAST modularization framework and allow for the simulation of coupled ice force, ice floe motion, and wind turbine structure response. This paper also presents example numerical simulation results of wind turbine dynamics using FAST coupled with these three new models.