风力发电机外文参考文献和翻译 Abstract There has been increased interest in implementing co-located renewable energy generation systems in urban areas, and vertical axis wind turbines (VAWTs) are a candidate technology for capturing the unsteady, omnidirectional winds that are typical of an urban environment. Before the technology can be widely deployed, the issues of reliability and environmental noise must be addressed. Knowledge of the structural dynamic response of the rotor blades as a function of the wind state that enters the rotor will facilitate a better understanding of both reliability (of the blades and driveline bearings) and noise (frequency content of the blade motions that causes structure-borne noise). An experimental modal
model was developed to relate the forces introduced by wind loads to the response of the structure. Experimental modal analysis was performed on a 600 W lift-type (Darrieus) VAWT for a range of azimuth angles and tower heights.Additionally, operational modal analysis was conducted in an indoor simulated wind environment test bed. A modal filtering technique was applied and verified using an electro-dynamic shaker and was then used to analyze the operational data.The effects of wind speed and shear on the modal response were investigated. The key results were a shift down in resonance frequencies with increasing height of the turbine tower for rotor modes coupled to the tower response and significant changes in operational modal response for non-uniform (sheared) wind conditions, especially from the 5 Hz mode of vibration.Future work will involve operational testing of vibration and acoustic emissions of the VAWT on a building rooftop.本文来自优/文(论"文\网，毕业论文 www.youerw.com 加7位QQ324~9114找原文
1 Introduction
VAWTs have been receiving renewed attention, especially for applications in urban environments since their low tip speeds translate to lower aeroacoustic noise emissions than traditional horizontal axis wind turbines [1]. Previous structural dynamic work was performed by Sandia National Laboratories on large (17 m and 34 m) experimental turbines, which were of a 2-blade parabolic design and had fairly high rotation speeds [2]. Most new designs are 3-bladed, are generally small (<5 kW), and some incorporate twisted, helical blades, which are meant to reduce torsional oscillations by maintaining a relatively constant solidity as they rotate [3]. VAWTs are being installed in urban locations and on building rooftops because of their ability to accept wind from all directions, making them impervious to yaw error, as well as their lower aero-acoustic emissions. The close proximity to people makes vibration and structure borne noise transmission important considerations. It is also important to classify how the turbine responds structurally to the dynamic wind environment, and to determine how to place urban wind turbine systems to maximize power output and component lifetime.
2 Experimental Modal Analysis
Two separate modal impact tests were performed. The first test focused solely on analyzing the turbine modes, as well as determining sensor placement and impact locations for subsequent modal tests. The second test took place with the turbine installed on a telescopic tower inside the laboratory, and included the tower response and its coupling effects with the rotor response.3572