A forced air open-ventilation systems for cooling electrical machines is provided. The forced air open-ventilation system includes an air cleaner having an air chamber with a first end, where air is drawn in from the surroundings, and a second end, opposite the first end, where air is drawn out of the air chamber, via a first outlet. A rotating means is contained within the air chamber and may be driven to rotate about an axis that extends between the first end and the second end of the chamber. The rotating means applies a centrifugal force to any airborne particles entering the air chamber and throws them radially outwards from the central axis. These particles are then drawn out of the air chamber, via at least one second outlet formed adjacent to a radially outer edge of the rotating means, by a high-velocity outlet stream of the open-ventilation system.