The Effect of the Width and Number of Gaps on the Characteristics of Swirl Flow Induced Naturally inside Split Channel Using Hot Air Inlet

Abstract

Split channels are commonly employed in research laboratories to generate fire whirls. The purpose of this computational study is to investigate the effects of the width and number of side gaps on the performance of the split channel when hot air enters at the base of the channel instead of using a fire. Three cylindrical channels are modeled. The first channel includes two identical slots, the second channel has only one gap with a width double that of the first channel, and the third channel comprises one gap identical to that of the first channel. Comparisons between the results of the first and the second channel provide the assessment of the impacts of the number of gaps on the performance of the split channel. Moreover, the comparison between the results of the second and third channels shows the effect of changing the width of the gap. The combined (overall) effects of the number and the width of the gaps on the characteristics of the flow within the channel are also evaluated by comparing the results of the first and the third channel. The results show that increasing the number of the slots without increasing the total area of the gaps leads to an increase in centerline vorticity within the channel. In addition, the inlet velocity of hot air from the base and entrainment ratio decreases with the increase of the number of the side slots. Increasing the width of the gap without changing the number of the slots reduces the entrainment velocity, the inlet velocity, but the entrainment mass flow rate and centerline vorticity increase. The entrainment mass flow rate centerline vorticity and entrainment ratio increases by the increase in the number of identical gaps and the increase of gap width whereas the entrainment velocity and the inlet velocity decrease.