Swirling annular impinging jets under hysteretic behavior

This paper is focused on an annular impinging jet under hysteretic behavior, and on a possibility to control this phenomenon by means of jet swirling. An experimental study was performed with air as the working fluid using flow visualization, hot wire anemometry and wall pressure measurements. The bistability and hysteresis were confirmed, and two different flowfield patterns were revealed under the same boundary conditions. It was found that weak swirling (S=0.03) decreases a tendency to bistability and hysteretic behavior. The Reynolds number effect was also identified: the bistability and hysteresis exist only at small Reynolds numbers, less than 3000.