Abstract: An airflow guiding device for the sound- and pressure-optimized supply of an airflow to an inlet nozzle of a fan, in particular a radial fan, wherein the inlet nozzle has a nozzle input opening with an incident flow angle, the airflow guiding device having: a frame device which extends along a longitudinal axis in an axial direction with a height between an inlet opening, through which the airflow flows into the frame device in an operating state, and an outlet opening, through which the airflow flows out of the frame device in the operating state, wherein the inlet opening has an inlet cross section with a minimum inlet cross-sectional width, and the outlet opening has an outlet cross section with a minimum outlet cross-sectional width which corresponds to the minimum inlet cross-sectional width or which is smaller than the minimum inlet cross-sectional width, and the frame device comprises a flow duct which connects the inlet opening and the outlet opening in terms of flow, wherein the outlet opening is con

Abstract: A method for modifying a sound emission of a wind power installation, wherein the wind power installation comprises a nacelle and a generator with a rotor which is adjustable in terms of its rotational speed, and the rotor has at least one rotor blade, the generator produces sound with at least one characteristic generator sound frequency which depends on the rotor rotational speed, the wind power installation has at least one fan for cooling the nacelle and/or generator, the at least one fan is adjustable in terms of a fan rotational speed, wherein the at least one fan produces sound with a characteristic fan sound frequency which depends on the fan rotational speed, and the fan rotational speed of the at least one fan is set in such a way on the basis of the rotor rotational speed that the fan sound frequency deviates from the at least one generator sound frequency. Tonal sounds in wind power installations, or the perception thereof, are intended to be reduced in particular.

Abstract: An airflow guiding device for the sound- and pressure-optimized supply of an airflow to an inlet nozzle of a fan, in particular a radial fan, wherein the inlet nozzle has a nozzle input opening with an incident flow angle, the airflow guiding device having: a frame device which extends along a longitudinal axis in an axial direction with a height between an inlet opening, through which the airflow flows into the frame device in an operating state, and an outlet opening, through which the airflow flows out of the frame device in the operating state, wherein the inlet opening has an inlet cross section with a minimum inlet cross-sectional width, and the outlet opening has an outlet cross section with a minimum outlet cross-sectional width which corresponds to the minimum inlet cross-sectional width or which is smaller than the minimum inlet cross-sectional width, and the frame device comprises a flow duct which connects the inlet opening and the outlet opening in terms of flow, wherein the outlet opening is con