Understanding Vortex Characteristics in Hydraulic Systems: a Temperature-Driven Analysis

Hydraulic engineers confront challenges posed by free surface vortices at pump and power intakes, influencing turbine efficiency and causing hydraulic losses and blockage. This study investigates the formation and strength of vortices under different conditions, focusing on the influence of water temperature. Numerical simulations using the OpenFOAM package model the flow field towards a vertical intake, employing the Volume Of Fluid (VOF) and Large Eddy Simulation (LES) approaches to simulate free surface and turbulence. Validated against experimental data across temperatures ranging from 10 to 40 °C, the results reveal a direct correlation between vortex characteristics and temperature. In particular, vortices exhibit mild flow rotations and a slight surface drop (Class C), increased strength with potential debris draw (Class B), or capture and transportation of air bubbles to the intake, posing system risks (Class A). For instance, a 10 °C temperature decrease leads to a 29.5