Abstract: The flow structure around a pitching airfoil at constant rate is varied in different pitch rate regions,and the incidence at which the leading edge vortex begins to form is larger at higher pitch rate. For a given pitch rate,the leading edge vortex begins to form earlier when the initial incidence is higher.The effect of final incidence on flow structure is related to pitch rate,The leading edge vortex begins to form at lower incidence and the vortex size is bigger when a flat plane airfoil is pitched up.

Key words: airfoil profiles, pitch (inclination), flow distribution, flow visualization