Low Pressure Flow Free Fan Design Study

This paper in view of the low pressure and great flux characteristic of the free fan, takes the power fan as the object of study based on the numerical simulation and experiment test, conducts the research separately to the five primary factors of the free fan: the planform of blade, blade angle and the distribution situation of the blade, the relative camber ratio of the blade section, the forward-swept and the swept back condition of the blade, tip hub ratio. In this paper, some rules have been obtained: 1. On the modelling design of the planform of blade, the saber shape blade has great superiority, especially, the strong sweeping-curved technology and the sharp apex design technology which used in the saber shape blade's modelling design process can markedly improve the characteristic of the flow, reduce the ventilator noise, enhance the ventilator efficiency. 2. The relative camber ratio of the blade section should be 8%~4% for good, and should arrange in 40%~50% or 70%～80% of the section chord direction position, by now the ventilator might obtain the high value and air current quality. 3. The blade forward-swept can effectively improve the secondary flow in the apex area stack problem which is advantageous in enhancing the fan efficiency and the value. In this paper, it shows that the development cycle of the free fan and the development cost have been reduced, which provide the reference for opening the new mentality of the free fan design work. These works which have been done in this paper have certain theory and the project application value.