a housing radially surrounding

a fan wheel, said housing having an inner side which defines an air conveying conduit in which said fan wheel is arranged, said fan wheel being rotatable about a central axis and including a central hub having an outer periphery on which are mounted fan blades whose radially outer rims are each at a distance (d) from the adjacent inner side of the fan housing,

wherein each of said blades is shaped like an airfoil profile of an aircraft, the blades each being implemented in concave and sickle-shaped fashion on their front edge, in such a way that a radially outer end of a sickle is located, with reference to a rotation direction of said fan wheel, farther forward in a circumferential direction than a hub-side end of the sickle, and the blades are furthermore each twisted between said hub-side end and said radially outer end and have a convex rear edge, and along the twisted radial outer edge of each fan blade and adjacently to the inner side of the external housing,

a flow element is provided which has an outline analogous to that of the associated fan blade and which is implemented as a flow-pattern obstacle for a compensating flow proceeding around that twisted radial outer edge from the delivery side to the intake side, in order to reduce noise generated during operation by the equipment fan, and

wherein the flow elements each have a profile that, adjacent a front edge of a fan blade, increases from that front edge in the manner of the front edge of an airfoil, and tapers adjacent a rear edge in the manner of the rear edge of an airfoil.