Design and Experimental Validation of a Ducted Counter-Rotating Axial-Flow Fans System

Abstract

An experimental study on the design of counter-rotating axial-flow fans was carried out. The fans were designed using an inverse method. In particular, the system is designed to have a pure axial discharge flow. The counter-rotating fans operate in a ducted-flow configuration and the overall performances are measured in a normalized test bench. The rotation rate of each fan is independently controlled. The relative axial spacing between fans can vary from 17% to 310%. The results show that the efficiency is strongly increased compared to a conventional rotor or to a rotor-stator stage. The effects of varying the rotation rates ratio on the overall performances are studied and show that the system has a very flexible use, with a large patch of high efficient operating points in the parameter space. The increase of axial spacing causes only a small decrease of the efficiency

A numerical study on the unsteady effect of axial spacing on the performance in a contra-rotating axial compressor

“…In addition, a larger axial gap results in improvement in acoustic performance while degrading the aerodynamic performance, and the peak pressure point occurring at a lower flow rate. However, the study reported by Nouri et al 17,18 for axial gap changes from 10 to 50 mm indicates no obvious change in overall performance.…”

PIV Measurement of Inlet and Outlet Flow of Contra-Rotating Small-Sized Cooling Fan

“…Contra-rotating rotors have been adopted for some of the high power cooling fans to meet the demand for high power. On the other hand, low rotational speed design [5] and advantages on the performance of the contra-rotating fans and pumps were verified by experimental results [6]- [8]. The company's research and development period for the contra-rotating small-sized cooling fan was short and its internal flow condition was not clarified well.…”

Internal Flow Condition between Front and Rear Rotor of Contra-Rotating Small-Sized Axial Fan at Low Flow Rate

“…Therefore, the contra-rotating rotors are adopted for the small-sized axial fans to increase the performance. The lower rotational speed design [1] and advantages on the performance of the contra-rotating fans and pumps were verified by experimental results [2] [3]. In the case of contra-rotating rotors, the axial space becomes larger than conventional small-sized axial fans.…”