Assessment Of A New 0.2 Hub-To-Tip Ratio Propeller Fan Design With Rigid-Body Blade Loading

This paper presents the numerical assessment of a new 0.2 hub-to-tip ratio propeller fan with specific speed equal to 8.2, by means of an original low-order CFD modelling approach. The fan implements the rigid body blade loading distribution and it was designed by the authors using the classical “Kahane-Wallis” method. First aim of the work is to give a preliminary feedback on the possibility that the new fan improves the aerodynamic performance of a high-efficiency fan, which implements the constant-swirl blade loading. Second aim of the work is to verify the effectiveness of the “Kahane-Wallis” method for the design of very low hub-to-tip ratio fan rotors with rigid-body blade loading. The third aim is to present the new low-order CFD modelling approach that the authors conceived for a low-computational-cost preliminary estimate of the aerodynamic performance expected from ISO 5801 Type-A performance tests. The results demonstrated that the “Kahane-Wallis” method allows for rigid-body designs with very low hub-to-tip ratio and remarkably high pressure coefficients. However, such designs unlikely exceed the efficiency achieved by constant-swirl designs featuring lower pressure coefficients. Moreover, the successful application of the method is doubtful for designs with flow separation at the blade root or immediately downstream of the rotor. Finally, it is found that the new low-order CFD approach offers potentialities as a tool to support the preliminary fan design and deserves future investigations.