Characterization of Aerodynamic and Aeroacoustic Performance of Bladeless Fans
thesisposted on 14.08.2019 by Ang Li
In order to distinguish essays and pre-prints from academic theses, we have a separate category. These are often much longer text based documents than a paper.
Bladeless fans are well known for their unique shape and efficient performance, which have a great impact on the fan industry. At present, there are few studies on the bladeless fan and the research on the improvement of fan design is a lack. Therefore, the study on the performance of the bladeless fan with different design is the main purpose of this thesis.
In the present study, a bladeless fan prototype is created and studied by numerical simulations. When characterizing the aerodynamic and aeroacoustic performances of the bladeless fan, the entire fan prototype, including wind channel, base, rotor and stator, is adopted; when investigating the influence of the wind channel's geometric parameters, only wind channel is considered in simulations. The influence of the slit width, the height of the cross-section, the slit location and the profile of the cross-section are studied.
It is found that the flow outside the bladeless fan consists of the air blown out from the wind channel and entrained from the back and side of the fan. The air entrained from the side is the main source of flow rate increase. As for the aeroacoustic performance, the rotor and stator inside the base are the predominated source of the noise generated by the bladeless fan.
The performances of the bladeless fan are very sensitive to the geometric details of the wind channel. The generated noise always increases as the wind strength improves. The slit width of the wind channel has the greatest impact. With the slit moves away from the leading edge, the wind produced by the bladeless fan becomes more powerful and the noise becomes louder. The cross-sectional height of 4cm has the best aerodynamic performance but the generated noise is a little larger than other designs. The profile of the cross-section shows insignificant influence on the performances.