CFD based flow analysis in elbow type draft tube for small hydro power plant

Draft tube is a component which recoups the energy at the outlet of a turbine. A great attention is given to the shape and performance of the draft tube for studying energy recovery. In this paper, an attempt has been made to carry out the flow analysis through a elbow type draft tube. The performance parameters at different operating conditions under variable submergence levels have been analyzed using commercially available ANSYS CFX code. Eighteen different cases of between mass flow rates under variable submergence levels are investigated and results are shown in the form of head loss, head recovery coefficients and efficiency of the draft tube. It has been found that at high submergence level efficiency and head recovery value is found to be maximum with low value of head loss coefficient.