Redesign of the Mini Hydro Turbine Structure Using Finite Element Analysis (FEA) to Solve Resonance Problem

Abstract

This study investigates the structural redesign of a mini hydro turbine system in an effort to solve the turbine shaft resonance problem. The original design of the turbine shaft support is examined to identify the root causes of the problem, which result in the failure of the turbine bearings. In order to approximate the natural frequencies, finite element analysis (FEA) models are developed and verified through comparison with experimental data, which may consist of modal analysis, coast-down testing, and deflection tests. Experimental results deviate from the FEA analysis of mode 1 frequency by 6.81%. Analysis of the linear dynamic response reveals that the amplitude of the shaft coupling's vibrations during system start-up and shutdown exceeds the allowable design parameters; this is the primary cause of bearing damage. FEA is used to redesign the shaft structural support in order to eliminate the natural frequencies. Modes 1 and 2 exhibit frequency shifts of 14.57 to 38.16 Hz and 11.36 to 37.57 Hz, respectively. These values are double the frequency at which a typical generator operates. The maximum shaft support deflection is reduced from 0.25–0.39 mm to 0.01 mm, according to the FEA results. Utilizing the redesign parameters, a new shaft support will be constructed. To confirm the FEA results, it is possible to monitor and recheck the data.