The Hydraulic Characteristics Analysis Of The Turbine Ring Gate In Shut-down Process

This dissertation takes the whole passage of the hydraulic turbine as the modeland simulates the ring gate emergency shut-down process which is one of theprotective measures to ensure safe operation. In order to grasp the hydrauliccharacteristics of the ring gate and other components, it uses the fluent software tosimulate and analyze the hydraulic characteristics variation of the pressure, velocity,moment, flow rate and moment in the ring gate60seconds shutdown process as wellas the small opening of the ring gate. The main research contents and results are listedas follows:(a) Combined with the ring gate actual operating condition, when the runnerspeed is170rpm, it takes its result as the initial calculation of unsteady flow fields.The ring gate movement is defined by the profile. Mesh refinement, sliding mesh,dynamic mesh is use to adapt to the change of the flow field. Using the RNG k-εturbulence model and SIMPLEC algorithm to simulate and get the iterative solution.(b) Through the numerical simulation, we can get the axial hydrodynamic forcesof the upper, bottom, inner and outer surfaces, and analyze the hydraulic characteristiccurves. Due to the instability of the pressure and velocity field surrounding the ringgate, there is the moment acts on the ring gate during the shut-down process. So weevaluate the ring gate overturning stability, and to analyze its overturning and whetherit will be got stuck, which can provide a reference for the safe and stable operation ofthe actual ring gate.(c) The numerical simulation focus on the hydraulic characteristic in smallopening of the ring gate. The simulation is performed again. Firstly, to get andanalyze the flow rate and velocity characteristic curves in ring gate area. Secondly,mark the points at different locations during the shut-down process to research thevariation. Thirdly, analyze the pressure and velocity field in ring gate surroundingarea, guide and static vane area, and runner area in ring gate small opening. Duringthe process, there are vortex, flow separation, reflux, secondary flow, work flow andaccompanied with cavitation, vibration and other instabilities. The solution provides a reference for the ring gate operation optimization, andtaking appropriate measures to make it run more efficient and stable.