The Effect of Atomizer Position in a Curved Duct on the Humidification Process of Steadily Flowing Air


An experimental study is conducted on the utilization of water atomization to evaluate its impact on the humidification of steadily flowing air travelling throughout a curved portion of a uniform cross sectional duct. One of the more interesting aspects of curved channel flows is the introduction of a secondary flow pattern in the duct cross-section. The naturally generated turbulences in air flow will certainly assist the mixing between the air and the injected water droplets and improve the heat and mass transfer process encountered in evaporative cooling of the incoming air drought. The present study is considered as a simulation of the gas turbine inlet air cooling by the fogging technique. The drier the air, the better the humidification and cooling process. At higher ambient temperature of 43oC, an increase in the relative humidity of 67.8% and a temperature reduction of 39.6% were recorded at higher water atomizer rate of 24.2ml/s. Generally, the lower half of the curved duct is shown to be less sensitive to the atomizer position for a range of inclination angles between 10o to 45o with radial locations between 5 to 20cm from the inner wall. This situation makes this region most suitable for using atomizing array across it in order to give acceptable performance for cooling system. Nevertheless, the upper half of the curved duct introduces a critical atomizer position suitable for single point spray. This position is considered as the optimum atomizer position defined by a radii ratio of (r/rin = 3.2) and an orientation of -10o to the tangential flow.