Wind turbine blade having a spoiler with effective separation of airflow

A blade (10) for a rotor of a wind turbine (2) having a substantially horizontal rotor shaft, said rotor comprising a hub (8), from which the blade (10) extends substantially in a radial direction when mounted to the hub (8), the blade having a longitudinal direction (r) with a tip end (16) and a root end (14) and a transverse direction, the blade further comprising:

• a profiled contour (40, 42, 50) including a pressure side and a suction side, as well as a leading edge (18) and a trailing edge (20) with a chord having a chord length extending there between, the profiled contour, when being impacted by an incident airflow, generating a lift, wherein the profiled contour is divided into:
• a root region (30) having a substantially circular or elliptical profile closest to the hub,
• an airfoil region (34) having a lift-generating profile furthest away from the hub, and
• a transition region (32) between the root region (30) and the airfoil region (34), the transition region (32) 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, and wherein
• the blade is provided with a flow guiding device (70) added to the profiled contour (40, 42, 50) of the blade on the pressure side (52) of the blade (10), the flow guiding device (70) having an inflow surface (72) with a start point (74) oriented towards the leading edge (18) of the blade (10) and an end point (76) oriented towards the trailing edge (20) of the blade (10), the distance between the inflow surface (72) and the pro filed contour (40, 42, 50) increasing from the start point (74) to the end point (76), and wherein
• the flow guiding device (70) extends along at least a longitudinal part of the transition region (32) and is arranged so as to generate a separation of airflow along at least a central longitudinal portion (71) of the flow guiding device (70) from the pressure side (52) of the blade (10) at a point between the flow guiding device (70) and the trailing edge (20) of the blade (10), when the blade (10) is impacted by the incident airflow, the flow guiding device having a rear edge, with a rear edge height, wherein the rear edge height is substantially constant in at least a central longitudinal portion (71) of the flow guiding device (70), such that the central longitudinal portion (71) is at least 50% of the longitudinal extent of the flow guiding device (70) wherein
• the inflow surface (72) in at least the central longitudinal portion (71) is formed so that, for each transverse cross-section, an end point tangent (80) to the inflow surface (72) at the end point (76) crosses the profiled contour (40, 42, 50) at a crossing point (82), where the profiled contour (40, 42, 50) has a profile tangent (78) to the profiled contour (40, 42, 50), and wherein an acute angle (a) between the profile tangent (78) and the end point tangent (80) is at least 45 degrees.