Abstract: A fan assembly includes a tubular housing and electrodes which ionize air and cause the air to be filtered and to move through the tubular housing without use of moving parts, such as an impeller, thereby providing air filtration and ventilation without generation of vibrations and acoustic disturbances. An electric potential is applied between a longitudinally-oriented needle electrode and a planar or curved transversely-oriented net electrode disposed within the housing downstream of the needle electrode, thereby forming a longitudinally asymmetric electric field that ionizes and accelerates air molecules toward the net electrode, carrying the air molecules past the net electrode and through the air outlet. The assembly further includes a tubular duct electrode disposed within the housing on the outlet side ofthe net electrode, which collects ionized particles precipitated from the air.

Abstract: A bi-directional fan includes asymmetrically-shaped fan blades wherein, at each transverse cross-section of the blade, the profile of the blade includes a leading portion lying on one side of a straight line connecting the leading and trailing edges of the blade and a trailing portion lying on the opposite side of the straight line. The leading portion of the blade is larger than the trailing portion of the blade, and the point at which the blade's mean line of profile crosses the straight line is closer to the trailing edge than the leading edge. From the leading edge to a point of maximum camber, the shape of the profile of the blade is described by a polynomial expression. From the point of maximum camber to the trailing edge, the shape of the profile of the blade is described by a cosine wave function. The larger leading portion presents a greater forward-curved surface area which allows the blade to move air more efficiently in the forward direction.