Development of a 5kw Francis Turbine Runner Using Computation Fluid Dynamics
A small scale Francis turbine runner for a turbine located at Awba dam in the University of Ibadan with designed head and flow rate of 6m and 0.244m3/s is designed. The basic design of the Francis turbine runner is completed based on basic fluid dynamics turbo machinery principles. A 2-D and 3-D steady state, single-phase CFD analysis is conducted for the runner, stay vanes, guide vanes, spiral case and draft tube of Francis turbine using two commercial CFD codes (ANSYS FLUENT and Solidworks Flow Simulation). The dimension of the runner is obtained from empirical formulas using the available head and flow rate. The runner is then optimized using CFD analysis to get required shape and performance. Performance of turbine is predicted at different guide vane openings. Cavitation and flow separation analyses are also conducted using a 2-D, steady state and two-phase (water vapour and liquid water) in order to reduce their occurrence in the designed runner. A hydraulic efficiency of 68.2% was obtained.
Keywords: Fluid dynamics, hydro-turbines, cavitations, CFD, flow separation