Oxygen Transfer Similitude for Vented Hydroturbine

Abstract

A similitude relationship for the oxygen transfer that occurs in a vented hydroturbine is developed with reference to scaling between a homologous turbine model and a full-size turbine installation (prototype). Three basic parameters are identified as important for the scaling of oxygen transfer: the liquid film coefficient, the specific surface area, and the contact time. The similitude relation is then developed with existing theories on turbine hydrodynamics, bubble hydrodynamics, and interfacial mass transfer. The only model-prototype data set currently available is used to empirically fit one coefficient and to test the theory. Model-prototype similitude for oxygen transfer is primarily a function of gas-void ratio, rotational speed, and runner diameter with diffusivity, surface tension, and density playing a lesser role.