Design and CFD Analysis of Bladeless Ceiling Fan

Conventional ceiling fans use convective effect to distribute air to surroundings. The fan blades deflect the air downwards to produce a draft of air resulting in cooling of the room. However, this draft is delivered in form of gusts along with an uncomfortable noise induced by the blade-air interaction and resulting pressure fluctuations due to turbulence and unsteady flow phenomenon. Bladeless fans provide excellent solution in this regard. Bladeless fans are type of fans which do not contain visible blades or vanes. A motor rotor or radial impeller is used to direct flow inside the geometry of bladeless fan which is multiplied at outlet using Coanda effect. Currently, bladeless fans being used are of desk type providing sufficient air for one to two people. For air supply to the whole room, application of bladeless fan as a ceiling fan is studied in this paper. Bladeless fan is designed using Eppler 473 airfoil in SolidWorks. Flow of bladeless fan is simulated inside a room of dimensions
$3.5\mathrm{m}\times 3.5\mathrm{m}$
room. Parametric analysis of bladeless fan is performed in ANSYS FLUENT to find optimum conditions at which bladeless fan yields maximum volumetric flow at outlet. Numerical model is validated by comparing numerical results to experimental model. Results showed that volumetric flow rate of bladeless ceiling fan increases with increase in fan to ceiling distance up to 0.3m and start decreasing as ceiling to fan distance increases beyond 0.3m. The volumetric flow rate of bladeless fan increases with increase in fan diameter and decreases with increase in nozzle diameter. Numerical results also showed that bladeless fans have similar outlet flow field as conventional ceiling fans with sufficient volumetric flow rate to be used as ceiling fans.