Turbulence in continuous flow surface aeration systems

Abstract

Turbulence characteristics in an optimal continuous surface aeration system were investigated in this study. The experimental system consists of a rectangular tank, where flow is driven by equally spaced aerators placed on the liquid surface. The mass-transfer coefficient and turbulent parameters at the tank's inlet and outlet were measured to enable analysis of their interdependent relationships. The turbulence parameters are linked closely to the system's mass-transfer process. Turbulent bursting analysis has shown that ejection and sweep events govern the hydrodynamics of the systems. Turbulent intensity increases with increasing speed of rotation, and consequently the mass-transfer coefficient also increases. The universal probability distribution functions of the velocity fluctuations in continuous flow surface aeration systems follow the Gram-Charlier series, based on exponential distribution, and the theoretical and experimental curves match.