Abstract:
Part load operations procedures affect pressure pulsations and vortex throughout Francis turbines hydropower plant. The goal of this study to investigate these two phenomena’s in the inlet of draft tube operated at part load. Unsteady stateflow and three dimensions presents a numerical investigation of water flow and air injection used in the purpose of reducing pressure pulsations and vortex in a typical draft tube of Francis turbines when using different part load discharges were performed using 70% QBEP, 60% QBEP and 50% QBEP at 33 m head in Merowe Dam Hydro power. Two sections were chosen and used during the numerical simulation to predicted pressure pulsations contour. One horizontal section was placed in the draft tube inlet below the turbine. Another was placed in the vertical section. Beside the vortex show was also included in the simulations.ANSYS Fluent was carried out for all the numerical simulation to explore various part load operations. Except for the 50% QBEP high pressure pulsations and vortex definite during part load operation. Air injection into the draft tubecone wall is installed to reduce the intensity of pressure pulsations and vortex that occur during part load from 12.36% to less than 5%, when injected to 5 bar, data have been comparedwith guaranteed value. The outcome of this research, demonstrates the potentials and benefits of using air injection in the draft tube to protect the units operation ranges by increasing operation area Hell Chart. Findings show the air can be introduced in various locations to reduce pressure pulsations in harmful operating regionsin Merowe Hydro power. Data have been compared with standard values and results reached up to date.
