In hydro turbines, the importance of draft tube is well known. Its function is to create positive suction pressure utilizing unused kinetic energy at the exit of turbine runner and hence to increase the effective net head on turbine unit. Till date there are no numerical methods or design procedure available for design of draft tubes, however they are designed based on the intuition and experiment of designers and are confirmed with experimental test study. In order to have good performance of draft tube, the magnitude of pressure recovery should be greater. In context to this, in the present paper, for a high head Francis turbine, various designs of bend type curved draft tube are made using conventional approach and their CFD simulations are carried out at Best Efficiency Point (BEP) and at off duty points of turbine having same flow physics but different geometry of draft tube. Modification of design is made by changing the hydraulic parameters of suction cone, elbow and exit diffuser. From these different trials, an optimum draft tube is selected by considering a tradeoff between the higher values of C_P and η_H.
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