Investigation of sediment erosion in low head Francis turbines and its effect on the structural integrity

Abstract

The geographical condition of Nepal has always challenged the hydropower plants in Nepal. The huge potential run-off rivers flowing through this terrain carry an immense amount of sediment. This sediment constitutes quartz particles with enough hardness, which corrodes the material of the hydraulic turbines and other components of the hydropower plant. The sediment erosion hindered the growth of hydropower plants as it significantly increased the maintenance cost and decreased the efficiency and life span of the plant itself. This paper takes this problem into account to investigate the structural integrity of one of the reference cases of eroded low head Francis turbine of Nepal by performing one-way FSI. CFD analysis was conducted on the single passage of the runner and structural analysis of the runner was conducted as well. For the structural integrity, the thickness of the blade at the trailing edge was decreased to 80 percent of its span. From the results of the structural integrity, the stresses imposed on the reference runner due to the erosion were observed to be within the allowable stress even in the extreme case condition.