DESIGN OF TOWER FOR WINDMILL SYSTEMS AND ITS COST EFFECTIVENESS

Abstract

Windmills have been extensively used for harnessing the natural, environment friendly and renewable energy in wind. These are mainly used for water pumping application and electricity generation. Their support towers are mostly of steel latticed or tubular type and are supported on suitable foundation. These towers are not only designed for wind loading but also for loading due to various operational conditions of the windmill. The loading is thus static, dynamic and fatigue in nature. All the possible loadings and type of towers generally used are described. Also all the formulations required for calculation of Forcps and Moments and Power of a Rotor, wind load estimation and design for fatigue damage are described. The forces and formulations given are applicable for both water pumping and electricity generation applications or low speed and high speed wind rotors. But in the present work, towers for only water pumping have been considered for design. The height of such type of towers varies between 21ft and 47ft. For detailed study, a typical 12m high tower is selected and base width has been considered as a design variable. The analysis of tower is carried out for changing base width using computer software "STAAD-PRO" and a dedicated computer program "TATWIN" specially designed for windmill towers. The results are comparable with a little higher value obtained in "TATWIN" for which the tower has been designed. Wind tunnel testing was also.carried out to study the response of tower for different windmill conditions and wind directions. The two conditions for a windmill can be: 1) stalled rotor and 2) rotating rotor. The response of tower without windmill has also been studied and results have been found in close agreement with previous wind tunnel testing.