Numerical analysis of flow in the upstream of runner inlet region of Kaplan turbine

Based on the average N-S equation and adopting κ-ε turbulence model, numerical calculation was performed on the investigation internal flow characteristics of Kaplan turbine. By analyzing the distributing rules of axial velocity and torque velocity in the flow region including from outlet of guide vane to runner inlet under different conditions, it can show influence of flow passage turn to runner inlet on the different guide vane angles. In the small discharge operating condition, the flow passage turn can change the distributing rules of axial velocity and enhance torque velocity. In the large discharge operating condition, the flow passage turn can balance axial velocity and reduce torque velocity. These investigations can provide theoretical foundation to ascertain the position of runner blade inlet edge, which can be used for optimization of blades and improvement of the turbine efficiency.