Experimental Study of Non-Isothermal Diverging Swirling and Non-Swirling Annular Jets with Central Aspiration

• Published in: The International journal of ventilation 2010-03, Vol.8 (4), p.347-357
• Main Authors: Penot, François, Pavlović, Miloš D.
• Format: Article
• Language: English
• Subjects: annular jet; central aspiration; experimental method; impingement; non-isothermal flow; Physics; swirl flow; tornado
• ISSN: 1473-3315; 2044-4044
• DOI: 10.1080/14733315.2010.11683858

An experimental study of annular jets with central aspiration is presented. Two flow regimes were studied for creating either local air conditioning or local ventilation systems. The local air-conditioning system was developed by maintaining the same flow rates of the non-swirling annular jet and central aspiration. A new concept of a 'local ventilation system' was created by combining the swirling annular air jet impinging on the plate and central aspiration. Due to the rather small consumption of energy, the tested air-conditioning and ventilation systems are very functional and capable of maintaining local and confined micro-climate or ventilated zones in large volumes. In order to study dynamic and thermal conditions in the air conditioning system an experimental rig was built and tested. The results of the experimental research, using visualization and thermocouple measurements as well as 2D velocity fields obtained by a LDV system are presented and discussed. The visualizations show the existence of a stable calm low velocity zone in the core of the annular air jet. The thermocouple measurements, as well as LDV measurements, prove the dynamic and thermal stability of the region. A dynamically and thermally defined stable local zone is a protected volume where comfort conditions can be maintained. Velocity measurements also show the size of the vortex located between the annular jet exhaust and the central air return. Another experimental rig was built in order to study the conditions created by the proposed ventilation system. The presence of an aspirating ascending jet in the form of swirling flow - tornado, was registered between the proposed device and the impingement plate. This flow regime is very efficient in ventilating the local zone.