A design for the fail-safe mechanism of a guide vane in a Francis-type hydro turbine is proposed and analyzed. The\nmechanism that is based on a shear pin as a sacrificial component was designed to remain simple. Unlike the requirements\nof conventional designs, a shear pin must be able to withstand static and dynamic loads but must fail under a certain\noverload that could damage a guide vane. An accurate load determination and selection of the shear pin material\nwere demonstrated. The static load for various opening angles of the guide vane were calculated using the computational\nfluid dynamics Fluent and finite element method Ansys programs. Furthermore, simulations for overload and dynamic\nload due to the waterhammer phenomenon were also conducted. The results of load calculations were used to select\nan appropriate shear pin material. Quasi-static shear tests were performed for two shear pins of aluminum alloy Al2024\nsubjected to different aging treatments (i.e. artificial and natural aging). The test results indicated that the Al2024 treated\nby natural aging is an appropriate material for a shear pin designed to function as a fail-safe mechanism for the guide\nvanes of a Francis-type hydro turbine.
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