Numerical Simulation Of The Flow Field And Cavitation Characteristics Of Two Spillways

The high-speed flow problems of the discharge structure are cleared up and analyzed, and the several ways to study the hydraulic characteristics of the discharge structure are introduced. And we laid a strong emphasis on the numerical simulation of the hydraulic characteristics of the discharge structure based on the theory of the numerical simulation of the turbulent flow.In view of the extensive application of the numerical simulation on the issue of the hydraulic characteristics of the discharge structure, the 2-D and 3-D numerical simulations are carried on the flow field of the spillway based on the simulation software Fluent. The standard k ?εturbulence model and the VOF model are used to describe the water flow and track the free surface flow in this numerical simulation. The detail data of the water depth, velocity, hydraulic pressure, and other hydraulic characteristics are attained, and compared with those which measured in the hydraulic model test. Through the comparison of the calculated and measured values of the two projects, it can be said that if the calculated model was simplified properly and meshed more reasonable, then, whether 2-D or 3-D numerical simulation can both accurately capture the free water surface. Because of the complexity of the hydraulic characteristics of the turbulence flow in asymmetrical flip bucket, the 2-D numerical simulation is difficult to accurately capture the pressure changes on the flip bucket. If you focus on the hydraulic characteristics of the flip bucket, it is recommended to use three-dimensional numerical simulation.A sophisticated 2-D numerical simulation is carried on a spillway tunnel, especially on a total of four different flow rate and gate opening conditions. The water surface, velocity and pressure field are calculated in the four conditions. Through the mesh refinement near wall, the velocity close to the wall is obtained. Compared the calculated and measured velocity values we can find that the numerical simulation results have higher accuracy on the full cross-section, the velocity error in some individual points is also controlled within 8%. And the numerical simulation can provide a more detailed velocity field distribution than the physical model. Through the comparison of the pressure between calculated and measured values we can find that: 2-D numerical simulation is able to simulate turbulence flow field in the symmetrical spillway, and the errors between calculated and measured values are all less than 5%. And also, the position of the maximum pressure is accurately captured, consistent with the measured value. Because of the simple, time-saving, efficient 2-D numerical simulation, it would be a good option to use 2-D numerical simulation to calculate. The flow cavitation numbers are educed by the calculated pressure and velocity in four different conditions and the variation of cavitation number are summarized. It is provide a reference and help to study on the phenomenon of cavitation near the wall. It also proposed some gate opening that the project should strive to avoid and the construction roughness requirements to prevent cavitation damages.