Abstract: The ultrasonic atomizer system serves to atomize fuel to be injected into internal combustion engines, thereby forming droplets of identical diameters (d.sub.T). The ultrasonic atomizer system includes an atomizer housing having a pressure chamber into which fuel is delivered under pressure by a pump. An ultrasonic vibrator protudes into the atomizer housing. Transport lines that transmit the vibrations lead from the pressure chamber to nozzles on the air intake tubes of the engine. A plurality of injection ports are provided in each of the nozzles and the streams of liquid emerging from the injection ports of each nozzle are made to undergo a monodisperse disintegration by the vibrations of the ultrasonic vibrator to form droplets of equal diameter (d.sub.T).

Abstract: A fan arrangement has an inlet bounded by an edge portion. A rotor has impeller blades which respectively sweep past the inlet. The edge portion forms an angle with each of the impeller blades so that noise generated by the blades during their rotation is substantially reduced. The edge portion may have any arbitrary shaped outline, such as linear, annular or curvilinear.