Abstract
Vertical-axis wind turbines (VAWTs) are being reconsidered as a complementary technology to the more commercially used horizontal-axis wind turbines (HAWTs) because of their economical installation and maintenance. The selection of the blade numbers is one of the crucial concerns for VAWTs. This study focuses on the effects of the blade numbers on the fatigue lives of VAWT tower bases subjected to wind loading. Three straight-bladed VAWTs, with the same solidity ratios but different blade numbers, varying from two to four, were designed. The aerodynamic loading incurred by the VAWTs was computed using the corrected double-disk multistreamtube (DMS) model. The dynamic equations of the turbine systems were solved using the explicit central difference method. Then, a fatigue assessment model, including the crack-initiation and crack-propagation stages, was developed for the turbine tower bases. The results indicate that the three- and four-bladed VAWTs always presented better performances than the two-bladed VAWT in terms of the fatigue life. Moreover, increasing the number of blades from two to three improves the fatigue life of the tower base more than increasing it from three to four at lower wind speeds, while the latter is the more effective way to improve the tower-base fatigue life at higher wind speeds.
Highlights
Wind energy is the fastest growing renewable clean energy source
The standard deviations (STDs) of aerodynamic loading show obvious decreases with the increasing blade numbers, which confirms the discovery by Cheng et al [17]
Unlike many other engineering structures, the potential fatigue damage to Vertical-axis wind turbines (VAWTs) towers is most likely to occur at sites aligned with the crosswind direction
Summary
Wind energy is the fastest growing renewable clean energy source. At the end of2019, the global wind capacity was already up to 651 GW, which provided the world with5.3% [1] of its electric energy needs. 2019, the global wind capacity was already up to 651 GW, which provided the world with. In 2020, the new global wind power installations were at 90 GW, which brought the total wind capacity to 743 GW [2]. With the increasing development of wind energy projects, there has been much research on novel solutions and, in some cases, reviews of previous work in order to revitalize these solutions using new techniques. Vertical-axis wind turbines (VAWTs) belong to the latter category. VAWTs peaked during the 1970s and 1990s, and gradually faded out after that period because horizontal-axis wind turbines (HAWTs) were thought to have higher power coefficients [3]; there has recently been renewed interest in VAWTs, beginning in the 2010s. The reason is that VAWTs have several unique advantages, such as much lower noise levels, simpler power generation systems, and much higher structural stabilities compared to HAWTs [4]
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