Blade icing often occurs on wind turbines in cold climates. Blade icing has many adverse effects on wind turbines, and the loss of output power is one of the most important effects. With the increasing emphasis on clean energy around the world, the design and production of wind turbines tend to be large-scale. So this paper selected the 15 MW wind turbine provided by NREL (American Renewable Energy Laboratory) to study the influence of blade icing on output power. In this paper, a multi-program coupled analysis method named CFD-WTIC-ILM (CFD: Computational fluid dynamics; WTIC: Wind Turbine Integrated Calculation; ILM: Ice loss method) was proposed to analyze the whole machine wind turbine. Firstly, Fensap-ice was used to simulate the icing of the wind turbine blades, and then the icing results were input into WTIC for the integrated calculation and analysis of the wind turbine. Then, the WTIC calculation results were used to simulate SCADA (supervisory control and data acquisition) data and input into ILM to calculate the power loss. Finally, this paper analyzed the comprehensive influence of icing on output power. The calculation results show that the ice mainly accumulates on the windward side of the blade. Icing has a great influence on the aerodynamic characteristics of the airfoil, leading to a significant decrease in the power curve. The rated wind speed is pushed from 10.59 m/s to 13 m/s. The power loss of the wind turbine in the wind speed optimization stage is as high as 37.48%, and the annual power loss rate caused by icing can reach at least 22%.

This paper establishes a numerical model for simulating submarine surfacing through the ice. The numerical model is simplified to be the interaction between a submarine and an ice sheet. The ice sheet is discretized into a number of ice material particles, and the motion and the failure of them are calculated by the peridynamic method. A contact detection method is used to determine the interpenetration between ice material particles and the submarine. To verify the feasibility of peridynamics in modelling ice failure, the two cases of three-point bending of columnar ice and vertical penetration of ice sheet for a cylinder are simulated. Convergence studies are taken with respect to the particle spacing size for submarine surfacing through ice. The surfacing process of the submarine has been simulated, and the calculation results are discussed. The calculated ice failure feature is similar to the full-scale observation.

The aim of the paper is to propose a groundbreaking method for the aerodynamic optimization design of the bioinspired wing with leading-edge tubercles. An emphasis on the optimization design of the spanwise waviness in the leading edge for delaying stall and increasing lift from the aerodynamic performance perspective has been laid in this study. For the conversion of the wavy configuration, the form parameterized approach using F-spline curves has been used to produce more variants of the leading-edge tubercles. Numerical investigations of flow characteristics which are performed using CFD computations have been used to validate the numerical scheme with experimental data. The combination of Non-dominated Sorting Genetic Algorithm II and Response Surface Method based Kriging Model has been adopted as the aerodynamic optimization strategy. As consequence, the three main components of the optimization process are incorporated into the establishment of the aerodynamic optimization design system for the bio-inspired airfoil with leading-edge tubercles. The four optimal airfoils respectively which increases the stall angle as well as the lift have been obtained in contrast to the smooth wing. The optimized bio-inspired design of this kind can be applied to flow-controlled devices for improving the efficiency of a particular operating mechanism.

The full exploitation of offshore wind resources can essentially satisfy the massive energy demand. The realization and application of ultra-high-power offshore wind turbines are crucial to achieving full use of deep-sea wind energy and reducing the cost of wind power. For the VolturnUS-S semi-submersible floating foundation of a 15 megawatt (MW) offshore wind turbine, the effect of structural parameters on hydrodynamic performance was investigated by controlling the variables described in this paper. Accordingly, the floating foundation was optimized and coupled to the 15 MW offshore wind turbine. The dynamic performance of the integrated 15 MW offshore wind turbine was analyzed under different operating conditions, by applying the aero-hydro-servo-elastic coupled method. The results show that for a wave in a 0-degree direction, a 5% increase of column spacing will reduce the peak value of the pitch transfer function by 33.61%, and that a 5% decrease of the outer column diameter will further reduce the peak value by 26.27%. The standard deviation of the time-domain surge responses was reduced by 19.78% for the optimized offshore wind turbine, and the maximum value of the mooring line tension was reduced by 13.55% under normal operating conditions.