A common blade design methodology for low solidity fan rotors is based on blade element theory combined with empirical airfoil lift and drag data. Often the required airfoil characteristics have to be estimated from existing wind tunnel data, roughly estimating the effects of Reynolds number and airfoil modifications such as trailing edge thickening. This contribution presents an extension of that methodology: Polar curves are computed during the fan design procedure and applied to each blade element. Reynolds and even Mach number as well as all geometrical features of the airfoil are fully taken into account. For that the public domain code XFOIL for analysis of subsonic isolated airfoils by Drela and Youngren has been integrated in an existing blade design code. The paper summarizes blade element theory and points out the interface where XFOIL data enter. A case study demonstrates how the airfoil specification affects the fan blade design. Two fan rotors for the same duty point but with NACA 4512 and FX60-126 airfoil blades are compared. Moreover, the effect of trailing edge bluntness on the blade shape is investigated.

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