TORSIONAL DYNAMIC OPTIMIZATION OF WIND POWER GENERATORS | ||||
| The International Conference on Applied Mechanics and Mechanical Engineering | ||||
| Article 12, Volume 12, 12th International Conference on Applied Mechanics and Mechanical Engineering., May 2006, Page 625-642 PDF (555.6 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/amme.2006.41380 | ||||
 View on SCiNiTO | ||||
| Author | ||||
| KARAM Y. MAALAWI | ||||
| Associate professor, Dpt. Of Mechanical Engineering, National Research Center, Dokki, Cairo, Egypt. | ||||
| Abstract | ||||
| ABSTRACT The present paper develops an appropriate optimization model for placing frequencies of a typical wind rotor/tower structure in free torsional motion. The aim is to avoid large amplitudes caused by the yawing-induced vibrations in the case of horizontal-axis machines or rotational motion of the blades about the tower axis in case of vertical-axis machines. This can be a major cause of fatigue failure and might severely damage the whole structure of the wind generator. The mathematical formulation considers a single pole tower configuration having thin-walled circular cross section with constant taper along the tower height. The nacelle/rotor combination is modeled as a rigid mass elastically supported at the top of the tower by the torsional spring of the yawing mechanism. The resulting governing differential equation of motion is solved analytically by transforming it into a standard form of Bessel’s equation, which leads to the necessary exact solutions for the frequencies and mode shapes. Several cases of study are examined for different values of the yawing stiffness and damping parameters by considering both conditions of locked and unlocked yawing mechanism. Useful design charts are developed for placing the frequencies at their needed target values with no penalty of increasing the total structural weight of the system. In all, the developed model guarantees full separation of the system frequencies from the critical exciting torsional frequencies by the appropriate choice of the optimization design parameters. | ||||
| Keywords | ||||
| Structural dynamics; Design optimization; Wind Turbines | ||||
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