CFD ANALYSIS FOR SILT EROSION FOR DIFFERENT SHAPES OF SILT PARTICLES

Abstract

Small hydro power is the renewable form of energy which uses the energy of water to generate electricity. 1-lydro turbine is considered as the main component of hydro power plants which encounter some problems like cavitations and silt erosion which reduces the efficiency over a period of their operation and decrease their operating life that results in increase in the cost of power generation. Almost all the power plants in the l-Iirnalayan region are affected by excessive silt in rivers that reduces the life of plant due to erosion of turbine components. The erosion of components strongly depends upon the silt size, concentration, hardness, shape, velocity of water, impingement angle and turbine materials. Experimental studies. investigations through CFD and theoretical studies were carried out and are available in the literature. It has been found that investigators discussed the silt mechanism on the theory that the silt particles present in water applies a force on turbines component and responsible to erode the material From the component. Silt also cause removal of base material change the runner profile and also weakens its structure. The efficiency of turbine decreases with respect to increase in erosion wear. Pelton turbine power output decrease with the increase of mass loss of bucket. Coarser particle cause erosion at inlet of bucket while smaller particle at the outlet of' turbine. These studies were carried out mainly to study the effect of silt concentration, silt particle size and flow velocity. 1-lowever, there is scope to investigate the shape of particle - size on the erosion of the turbine components. The objective of this dissertation is to carry out a study CFD analysis for silt erosion for different shapes of silt particles on the silt erosion for different shape factors in Pelton turbines. Under the present study a 3D model of Pelton turbine of capacity 1.5 MW is developed based on the earlier study in the GAMBIT software. Simulation for pure water flow and water with silt particles is done in Computational Fluid Dynamics (CFD) software. Then the effects of silt erosion with different value shape factors as 0.25, 0.5. 0.75 and I of silt particle and its effect on turbine efficiency is studied. Based on the investigation it is found that the erosion rate is found maximum for shape factor of 0.5. Further an attempt has also been made to study the erosion rates for different material turbine bucket. The results show that the erosion rate for copper is more than steel but it is found to be less than the aluminum