Numerical Prediction Of Performance Of Hydraulic Turbine In Sandy Water

Nowadays, As long as the develops of computational fluid dynamics and computer technology, lots of 3-D cohesive computational fluid dynamics software has been applied in the hydraulic turbine's inner flowability analyses successfully. A stable and effective flow field is the most important guarantee of the promotion of a higher parametric, performance and stable development of modern hydraulic turbine. However, in loaded stream, the ablation of sand is the key factor which affects the hydraulic turbine's inner performance stability. Hydraulic turbine's discharge apparatus are made of scroll case, guide apparatus, runner and draft tube, which are interrelated and interact with each other. In addition, the ablation degree of discharge apparatus caused by sand is closely allied to the flow condition. The design theory of hydraulic turbine's discharge apparatus still not so perfect in the condition of solid-liquid flow, most project designs are based on the past experience, and modified under the guideline of fair-faced designs theory, as a result, it can't promise a stable performance of the hydraulic turbine, which design for working in loaded streams. To explore a new inner biphasic flow method of hydraulic turbine's discharge apparatus, this paper takes the integer relations of the whole discharge apparatus in to consideration, base on the N - S equation; calculate the numerical value of its inner flow; while sediments free media with the RNG k -εturbulence model and sediment solid-liquid media with k -ε- Ap turbulence model. Main achievements of this paper can be listed as follow:Firstly, Firstly, discharge apparatus' 3-D geometric models are established according to actual hydraulic design parameters of a specific station by nigraphics software; leads all the hydraulic turbine models into the gambit software, and makes a mesh division of the discharge apparatus.Secondly, make an analyze of the francis hydraulic turbine's 3-D steady turbulent of the whole flow passage with numerical simulation method separately in peak discharge, proper discharge and minimum discharge of sediments free media; set up the francis hydraulic turbine's performance forecast method based on CFD analysis, get the flow details of hydraulic turbine's inner discharge apparatus, and estimate the hydraulic turbine's performance from both fix quantity and quality aspect.Thirdly, use solid-liquid flow theory and Eulerian model of FLUENT, simulate the flow situations of solid-liquid media separately in peak discharge, proper discharge and minimum discharge when the station's hydraulic turbines work in loaded stream, suppose the amount, thickness and diameter of the grain is fixed; make it compare with work in sediment free flow and analyze the difference. And then suppose the diameter of grain is fixed, simulate the flow situations of solid-liquid media, analyze the difference when the amount and thickness of grain are different. Lastly, suppose the flow capacity, amount and thickness of the grain are fixed, compare the flow situations of different diameters of grain and analyze their difference.Finally, through using and analyzing software FLUENT, find out numerical simulation's deficiencies, and make its corresponding develop expectation.