Study on Effect of Turbine Operating Conditions on Conical Draft Tube Performance

Hydraulic turbines play a prominent role in the energy sector based on the fact that they converts hydro energy into mechanical energy to produce electricity. In the reaction turbine, the draft tube transfers water from the runner outlet to the tail race and helps in the recovery of the kinetic energy leaving the turbine by creating a low pressure at the runner exit and thereby increasing the turbine net working head. The flow inside each component of the turbine is highly complicated and the whirling flow at the runner exit and its distribution along draft tube makes the flow complex inside the draft tube significantly. Therefore, Computational fluid dynamics is being used for the design improvements, investigations and to assess the performance of the draft tube. In this paper, 3D viscous turbulent flow simulation in a straight conical draft tube has been performed using CFD code Ansys CFX for different cylindrical velocity components such as axial component, radial component and theta component. Head loss and Efficiency are calculated for each case based on the simulation results and draft tube performance is analyzed.