Effects of plume spacing and flowrate on destratification efficiency of air diffusers

This study adopts techniques of computational fluid dynamics (CFD) to analyze the combined effect of adjacent plumes of an air-diffuser system on its destratification efficiency. Lab experiments were carried out to calibrate and verify the CFD models in thermally stratified freshwater. The CFD simulation and lab experiment results were analyzed to relate destratification efficiency with four non-dimensional variables. The results indicate that destratification number, DN, has the best relationship that includes air flowrate, stratification frequency, water depth, and bubble slip velocity. Since plume spacing and air flowrate are the major control variables of the system, especially in the field, two charts showing the relationships between destratification efficiency, plume spacing, and destratification number are developed for guiding their control in its design and operation.