Method of operating a wind turbine

A method of operating a wind turbine including a rotor comprising a wind turbine blade and having a substantially horizontal rotor shaft, the rotor comprising a hub, from which the blade extends substantially in a radial direction when mounted to the hub, the blade comprising:

• a profiled contour comprising a pressure side and a suction side as well as a leading edge and a trailing edge with a chord extending between the leading edge and the trailing edge, the profiled contour generating a lift when being impacted by an incident airflow,
• the profiled contour in the radial direction being divided into a root region with a substantially circular or elliptical profile closest to the hub, an airfoil region with a lift generating profile furthest away from the hub, and preferably a transition region between the root region and the airfoil region, the transition region having a profile gradually changing in the radial direction from the circular or elliptical profile of the root region to the lift generating profile of the airfoil region, wherein
• the airfoil region comprises a first base part having a leading edge and a trailing edge with a chord extending between the leading edge and the trailing edge, the airfoil region further being divided into at least a first longitudinal segment and a second longitudinal segment, the first longitudinal segment extending along at least 20% of a longitudinal extent of the airfoil region characterised in that the first base part has an inherent non-ideal aerodynamic design so that a substantial longitudinal part of the base part without flow altering devices at a design point deviates from a target axial induction factor, wherein the method comprises the step of:
• a) adjusting a pitch of the blade and a rotational speed of the rotor so as to meet the target axial induction factor of the second longitudinal segment, and wherein
• the first longitudinal segment is provided with flow altering devices so as to meet the target axial induction factor of the first longitudinal segment.