Numerical analysis of bladeless ceiling fan: An effective alternative to conventional ceiling fan

Abstract

A ceiling fan is one of the cost-effective alternatives for poverty-ridden societies and tropical countries short on natural resources. However, due to the inherent working principle, a lot of losses occur during electrical to mechanical energy conversion. Apart from losses, other problems associated with conventional ceiling fans are buffeting airflow, internal heating, and dirt accumulation on fan blades. Recently, the idea of a bladeless ceiling fan has been patented which has the potential to resolve most of the issues associated with the conventional fans, however, no details have been shared regarding flow physics and their effectiveness in constrained spaces. In this study, an annular type bladeless ceiling fan is computationally analyzed in a standard empty room (4m × 4m x 4m) environment. Parametric analysis of different design features such as fan radius, height from the ceiling and floor, fan jet width, mass flow rate, and orientations was studied and their effect on the perceived comfort level in terms of velocity spread and average velocities were captured computationally. The results show that the fan height in the close vicinity of ceiling does not affect the flow field in the occupied zones, however, as the fan gets closer to the floor the velocity field in the occupied zone changes due to creation of a strong vortex at the center of floor. Thus, fan installation closer to the ceiling (less than 0.5m from the ceiling) is a preferred choice. With an increase in fan radius from 0.3m to 0.5m, an increment of 33% was observed in velocity spread thus increasing the zone of influence. A finer jet width under the same volume flow rate produces higher velocities across the room e.g. 2 mm jet produces 36% higher average velocities as compared to 4 mm jet, which effectively increases zone of influence. Effect of jet orientation was also studied and a 90° (straight down) orientation produced better overall velocity spread in comparison with 110° and 130° orientation. In comparison with conventional fans, a minimum of 57% increment in velocity spread was recorded for all bladeless fan configurations under consideration in the present work. The flow physics of bladeless fan has prospects for further increment in the zone of influence by optimizing the geometric features in light of present work.