Recently, many of fans are designed by the inverse design method. The corresponding design methods for half-ducted types of propeller fans are not studied by many researchers. Among these types, a half-ducted axial flow fan is focused in this paper. In comparison with the conventional full-ducted fan mainly used in industrial applications, they are called as half-ducted type, semi-opened type and opened type, respectively. In most applications of fans non- ducted types are used for the space limitation or cost saving. For the case at rotor outlet at φ = 0.264, two values of the meridional velocity and the tangential velocity are larger than the design values at the tip side of the radial distribution.Ī lot of axial fans, which are small size and high efficiency, are used in our daily life, such as a power unit cooling fan of personal computer, a room ventilation fan, and a radiator fan in car engine room. In addition, the tendencies of the CFD values when the flow rate coefficient changes are almost similar as the experimental tendencies, though the flow rate coefficient for the CFD values when ψ or η takes the peak value shifts toward larger flow rate. For the comparison between the experimental values and the CFD values at φ = 0.264, the CFD values are almost the same values as the experimental values for all the values of ψ, τ and η. However, the experimental value of approximately 0.45 of the maximum efficiency is comparably large value considering for the limitation of the situation of half-ducted. For the comparison between the design values and the experimental values at the design flow rate coefficient of φ = 0.264, the experimental values of the pressure rise coefficient ψ and the efficiency η are rather small than the design values, while the experimental value of the torque coefficient τ is almost the same as the design value.
Then the designed half-ducted rotor with four NACA65 blades was fabricated by a three-dimensional printer and tested in the wind tunnel in order to validate the half-ducted design method. The improvement of the design is prospected for this point, that is, the approach between the design value and the actual flow is prospected if the tangential velocity is assigned small at hub and is assigned large at the tip so as to accord the actual flow in the vortex design of the rotor blade. On the other hand, the values of the meridional velocity and the tangential velocity are little smaller than the design values at the hub side of the radial distribution. As a result of the design and CFD, the meridional streamline and three distributions of the meridional, tangential and radial velocity at inlet and outlet go well as designed values of the half ducted fan. The rotor which has NACA65 blades was designed, calculated numerically, manufactured and tested experimentally. A study on the half-ducted axial flow fan designed by a diagonal flow fan design method was conducted.