Severity of Cracks Growths on Static Design of a Three Bladed Savonius Wind Turbine Using SolidWorks Simulation

Abstract

Modern vertical axis wind turbine is a promising technology, appropriate for small scale applications in urban areas and isolates sites for different uses. Including pumping water, producing electrical power, passive starting others turbines and purposes. The Savonius wind turbine is a robust and reliable mechanical device, easy to build, produces less noise. The formation and growths of cracks in this system reduces its stiffness and yield strength, which lead to a poor performance and system failure. The system works under the wind flow dynamic loading. Then, it is subject to mechanical and aerodynamical cyclic stresses to be inducing the fatigue and shortening the system lifetime. The diagnosis of the system by using nondestructive techniques based on magnetic particle, dye penetrant and ultrasonic are costly. The use of natural frequencies shift measured between uncracked and cracked structure is very small regardless the varying of crack depth and location, undetectable in the practice. The application of analysis and simulation tools based on (CAD) permits to evaluate the system design early in the design process. This technique allowed determining the causes of premature failures, quickly explored changes in the aim to reduce cost as well as weight, and estimated the safety factor of product. Present paper investigated the influence of weight and centrifuge force on the static design of a three-bladed Savonius wind turbine cracked under various wind speeds from 5 to 15 m/s. The transverse crack is formed and growth normally to the low speed shaft and to end side of blades. From simulation results, the reliability of wind turbine is strongly influenced by the increasing of wind speed since the security factor was decreased from 14.6 to 1.39. However, the influence of crack on mechanical proprieties of the system, stress, strain and displacement is very small, for all study cases, depth variation from 0 to 50% of the shaft diameter and at different settings. The effect is undetectable in the practice for in online monitoring of the wind turbine.