In recent years, Offshore Wind Power (OWP) has gained prominence in China’s national energy strategy. However, the levelized cost of electricity (LCoE) of wind power must be further reduced to match the average wholesale price. The cost-cutting and revenue-generating potential of offshore wind generation depends on technological innovation. The most recent studies and applications of offshore wind technology are thoroughly examined. (1) Techniques for site selection, such as site surveys, wind resource assessments, and environmental factors, are reviewed. (2) Three main technical components in offshore wind farms are discussed, including wind turbine, foundations, and booster stations. (3) The state-of-the-art method of the offshore wind farm’s construction and operation and maintenance (O&M) practices is discussed. In situ marine geological surveying, large-scale offshore wind turbine manufacturing, integrated structural design, floating foundation design, flexible DC transmission technology, shortage of specialized vessels and equipment for construction, intelligence of O&M, and other issues are challenging China’s OWP industry. A brief overview of China’s efforts in standardization, parity, and research and development are discussed. Recommendations for future development of the wind power industry are provided for China, which may be referable for other nations with comparable circumstances.

When discussing potential resonances in hydraulic turbine runners, cavitation effects are usually neglected. Nevertheless, recent studies have experimentally proved, that large cavitation volumes in the proximity of flexible simple structures, such as hydrofoils, greatly modify their natural frequencies. In this paper, we analyze a resonance case in a Francis runner that leads to multiple fractures on the trailing edge of the blades, after just one day of operation at deep part load. If simple acoustic Fluid-Structure-Interaction (FSI) simulations are used, where the runner’s surrounding fluid is considered as a homogenous acoustic medium (water), the risk of structural resonances seems to be limited as the predicted natural frequencies are far enough from the excited frequencies by the flow. It is shown that the only hydraulic phenomenon which could have produced such fractures in the present case is the Rotor Stator Interaction (RSI). In order to analyze possible cavitation effects on the natural frequencies of the turbine runner, CFD simulations of the deep part load conditions have been performed, which predict large inter-blade vortex cavities. These cavities have been then introduced in the acoustical FSI model showing that under such conditions, natural frequencies of the runner increase approaching to some of the RSI excited frequencies. In particular, a possible resonance of the four-nodal diameter (4ND) mode has been found which would explain the fast behavior of the crack propagation. Furthermore, the shape and the position of the real fracture found agree with the local maximum stress spots at the junction between the trailing edges and the crown.

Purpose: The purpose of this paper is to analyze lubrication characteristics of a tilting pad thrust bearing considering the effect of the thermal elastic deformation of the pad and collar. Design/methodology/approach: This study used the fluid–solid interaction (FSI) technique to investigate the lubrication characteristics of a tilting pad thrust bearing for several typical operating conditions. The influences of the rotational speed, the thrust load and the oil supply temperature on the lubrication characteristics were analyzed. Findings: The three-dimensional (3D) film model clearly shows that there is no pressure gradient but large temperature gradients across the film thickness. The wall heat transfer coefficients on the pad surfaces distribute in a very complex way and change within a large range. The rotational speed, the thrust load and the oil supply temperature have great but different influences on the lubrication characteristics. Originality/value: This paper has preliminarily revealed the lubrication mechanism of the tilting-pad thrust bearings. The 3D FSI method is suggested to evaluate the thermal-elastic-hydrodynamic deformations of thrust bearings instead of the conventional method which iteratively solves the Reynolds equation, the energy equation, the heat conduction equation and the elastic equilibrium equation. Using FSI method, the heat transfer coefficients on the pad surfaces can be evaluated better.