NASA Rotor 37 was selected as a baseline blade. Sweep features at tip regions were formed by moving the airfoil sections above the 90% span along the chordwise direction. There were five cases including the baseline rotor

two forward rotor and backward sweep rotors in total. A numerical simulation softwave was used to simulate the five rotors and obtain the overall characteristics and three-dimensional (3-D) flow fields. The results indicated that the tip forward sweep resulted in a decrease of inlet averaged incidence

while the backward sweep caused the reverse consequence. A circumferentially averaged method was introduced to provide the circumferential fluctuation terms as well as values in the inviscid momentum equation. The distributions of the circumferential fluctuation terms in the radial inviscid momentum equation at the blade inlet were calculated for comparison between the five cases

and were analysed for incidence variation. Forward sweep at tip regions resulted in the increase of axial velocity and reduction of circumferential velocity

further reducing the incidence due to the change of flow equilibrium at blade inlet

while backward sweep caused an inverse effect in the same region. The effect of blade sweep on flow fields at blade inlet was studied from the quasi-3-D perspective.