Laboratory-scale model for air vortex generation using passive and natural heating methods

Abstract This work discusses the design of an inexpensive and easy-to-operate experimental apparatus for the creation and visualization of air vortices using natural convection. The experimental setup consists of an upright clear tube with four tangentially mounted air inlets. Three experimental cases were explored: forced convection from the use of a hair dryer, natural convection from the use of a candle, and passive flow using smoke without the application of an external heat source. The experimental results indicated that the candle setup produced successfully an observable and sustained air vortex by creating a thermal gradient forcing the buoyant upward flow. The vortex creation was complemented by tangential air flow from the inlets, leading to spiralling motion as predicted from theory and computer simulations. This system provides an inexpensive teaching tool for vortex dynamics, convention, and atmospheric fluid flow in the educational setting.