Model Test And Numerical Simulation For Swirling Flow Of Inner Dissipator With Shaft Inlet

Inner dissipation discharge tunnel with level swirling flow and shaft inlet has many merits, such as high energy dissipation ratio, easy construction, flexible arrangement, low project cost, so the relevant study has important theoretical meaning and popularization value. The paper systemetically investigates the hydrolic properties of the level swirling inner dissipator and the factors which influence on it by model test on the one hand, on the numerical simulation hand, the paper has simulated the swirling flow field in the level discharge tunnel with Anisotropic k-ε Turbulence Model by programming, in addition with Second-moment Renolds Stress Model by utilizing CFX software.The model test shows that on the downstream of transition section the wall pressure diminishes along the tunnel on the whole, the paper presents its formula and analyzes its component factors in different flow pattern. For the transition section, when in different flow pattern, the transformation law between pressure energy and tangent, axial kinetic energy is different.Axial velocity shows parabola distribution along the radius, tangent velocity shows Rankine swirl distribution, and free swirl occupies most of the tangent velocity distribution. With the flow decays along the tunnel or the upstream water level reducing, axial and tangent velocity reduces and becomes to even along radius, the position of maximum value of tangent velocity moves towards axis. When the downstream water level reduces, theaxial and tangent velocity distribution along radius becomes even, tangent velocity diminishes. The bigger the downstream water level, the outstanding of variation degree of axial velocity along radius distribution when upstream water level is same. The correction coefficient for kinetic pressure pipe is 0.705 which is corrected according to wall pressure, cavity diameter, discharge volume.Based on the former studies on swirling flow, the paper analyzes each turbulence model's suitability on simulating swirling flow. Using Anisotropic k-e Model and Second-moment Renolds Stress Model to compute and presents when in up-middle stream, the simulation result of Anisotropic k-e Model accords with experimental data, but when in downstream, the result is different with measured result obviously. In contrast, the Renolds Stress Model is more proper to simulating swirling flow, getting variation law of wall pressure, velocity, dissipation ratio, turbulent kinetic energy, dissipation velocity. Results show that wall pressure, velocity accords with experimental data well. Turbulent kinetic energy, dissipation velocity diminishes along the tunnel, and on the same section dissipation velocity near the wall is higher.