Lin Zhe

Numerical Simulation on Flow Field of Bladeless Fan

With the advent of bladeless fan, technological revolutions begin to hit the industrial design world of fan. However, there is none of the developed methods on bladeless fan. To explore the excellent blowing performance of bladeless fan, numerical simulation on flow field of bladeless fan was carried out in this paper. Based on the simplified model of bladeless fan, the whole process that the airflow passes through the turbine from the inlet to the outlet slit and exit far field at last, were simulated. By comparing the flux of inlet and the flux of far outlet, the causes of flux increasing are analyzed. After analyzing static characteristics of the flow field, it shows that pressure difference is very obvious. The results obtained from velocity distribution and the characteristics of the pathlines near diffuser section and turbine, were described and analyzed. The results show that the internal flow field characteristics of bladeless fans, which we concern. The external flow field characteristics of bladeless fan was studied in the same way. And it is found that the velocity magnitude of the outlet slit and Coanda surface is much larger than other area and different positions play different roles. A general analysis on inside computational domain and outside computational domain, denotes the details about fluid motion. The research could offer reference to improvement of bladeless fan.Copyright

Effects of Blade With Perforation on Aerodynamic Performance of Dual-Rotor Small Axial Flow Fans

The static characteristics of dual-rotor small axial flow fans are better than that of single rotor small axial flow fans. While, compared with single rotor small axial flow fans, the noise of dual-rotor small axial flow fans highly increases. Regarding to this reason, the perforation blade are designed for dual-rotor small axial flow fans in this paper. Pre-stage blades, post-stage blades, and both pre-stage and post-stage blades were perforated respectively. The k–e turbulence model and the FW-H noise model were used to simulate. Then, the static characteristics and aerodynamic performance of the prototype fan and the fans with perforation blade were contrasted and analyzed. The results show that: In general, the pressure rising and efficiency of the fans with perforation blade declines slightly. Compared to another two perforation blade, and the pressure rising and efficiency of the fans of pre-stage perforating fan shows the smallest reduction, but increases slightly at the optimum operating condition; With the difference of perforation way, the variation of the noise level are different, while, in the outlet zones, the noise are all reduced;. The centralized region of vorticity in the trailing edge of the blades are reduced, and the noise of the fans are all reduced. All the results show that, using perforation blade can improve the aerodynamic performance of dual-rotor small axial flow fans.Copyright