Numerical and experimental research on the outlet flow field for the air multiplier

The outlet flow field of the air multiplier was simulated by a RNG k-epsilon model based on compressible fluid, and the simulated results were validated experimentally through a Constant Temperature Anemometer (CTA) hot-wire system and the ventilating multi-parameter testing instrument. The flow characteristics and the reason for the increase of the output flow rate relative to the turbine intake rate were revealed by investigating profiles of the time-averaged velocity and pressure. The results indicate that (1) the flow parameter profiles in the outlet flow field are not uniform, and the entire time-averaged velocity field and pressure field in near field are basically axis symmetrical in the horizontal direction instead of in the vertical direction; (2) the entrainment and suction effects resulted from the "coronary zone" of the established flow of high intense turbulence jet, enabling the air multiplier to realize "air multiplication", and the time-averaged velocity of the upper "coronary zone" and pressures in near field make greater contributions to the increase of flow rate. (3) RNG k-epsilon model is reliable on predicting the time-averaged flow behavior in the outlet flow field for the air multiplier. (C) 2015 Elsevier Ltd. All rights reserved.