Large Wind Machine Damping Blade Flutter Suppression Characteristics Research

Wind energy, a renewable and green resource, is playing a key role amongthe various patterns of energy. The new-adding capacity of installing windturbine in China ranks first in the world. By2015, China’s wind power runninginto the grid will reach the target of100million kilowatts, planed in theRenewable energy development in the “12th Five-Year Plan”. The process ofwind turbines and wind farms’ becoming larger and larger accelerates the windindustry development. With the size of wind turbines increasing, its cost for unitkWh of power generation decreases, and also the operational stability of thewind turbine is improving. Under the condition of complicated loads, the bladescan happen to flutter and twist which would cause the blades to be destroyed.Therefore, the flutter suppression for large scale wind turbine blades is the newurgent problem to be solved among the wind turbine technologies.The damping materials, mainly used in the field of control of vibration andnoise, can convert the mechanical energy into thermal energy which is dismissed.As to the flutter problem of large scale flexible blades, this study proposed theconcept of damping blades, which combines the traditional composites andadditional damping layer structure and suppress the flutter of bladessignificantly.This thesis first gave the main introduction on the suppression technologydevelopment, research status quo and the structure of wind turbine and its blades.According to the concept of damping blades, two patterns of damping bladeswas proposed which were the blades with free damping layer and the bladeswith embedded viscoelastic layer. And then, the suppression flutter dynamicmodels for those two damping were conducted based on the no-linearaerodynamic theory and their structural parameters were analyzed. At last, basedon a certain type of wind turbine blade parameters and ONERA nonlinearaerodynamic theory, numerical simulation was conducted between ordinary and damping blades under four conditions (start up wind speed, rated wind speed,safe wind speed and limited wind speed). The results show that damping bladescan significantly improve blades stability.