Performance of Aluminium A356 Alloy based Buckets towards Bending Forces on Pelton Turbines.

Abstract

Based on affordability, small turbines are forced to operate above optimum conditions in order to produce maximum power making them to fail under excessive water jet loading. Performance of Aluminium A356 alloy based Pelton turbine was evaluated under bending forces condition. The bucket experiences vibration due to repeated loading since it is mounted as a cantilever onto a disc. If not properly designed or manufactured, a resonance may occur and severely increase the dynamic stress causing failure. It is important to note that the design of the bucket ensures conversion of jet force into tangential force that eventually causes rotation. However, during this conversion shear and bending forces are induced at the regions where buckets are mounted to the turbine ring. Bending strength was analyzed with different properties of the buckets. It was observed that bending resistance is an important parameter that controls the turbine failure due to cyclic loading on the buckets. Alumina content was found to have significant influence on the bending performance of the buckets. Bending forces were predicted using structural analysis on ANSYS modeling software. The results were observed to lie in close proximity to the experimental results.