Flow visualization of a compound swirl jet with a thick rim

The conventional push-pull type ventilating system has two different functions: collection and ventilation. The entrainment flow of the jet is available for collecting suspended materials such as smoke, vapor and dust. In order to achieve more effective cleaning of dirty air, a compound swirl jet, which is composed of a coaxial annular swirl jet and a round free jet with a thick rim was proposed by the authors. A compound swirl flow has been shown to be very useful for the push-pull type ventilator by selecting the flow ratio of the annular swirl jet to the round free jet. As a fundamental study on the compound swirl flow, flow visualization was carried out using the smoke method to clarify the structure of the flow interaction between the round free jet and the annular swirl jet, respectively. As a result, a most suitable flow ratio for a push flow of the push-pull type ventilator was found to exist.