Abstract: An ultrasonic spray nozzle includes a piezoelectric transducer which develops mechanical vibrations in response to an applied periodic electrical potential. The vibrations are mechanically amplified and propagate to an atomizing surface over which fluid to be atomized is discharged by an internal fluid passage. Maximum vibrational amplitude of the atomizing surface is achieved when the frequency of the applied electrical potential equals the natural resonant frequency of the nozzle. A parameter of the applied electrical potential, such as frequency, is periodically varied such that the vibrational amplitude of the atomizing surface is periodically increased and decreased. Fluid atomization is reduced during periods of reduced vibrational amplitude permitting fluid to be distributed with greater uniformity onto the atomizing surface. Such uniform distribution results in a significant improvement in the definition of the spray pattern produced by the nozzle during periods of increased vibrational amplitude.

Abstract: In an orifice and nozzle for the passage of fluid which may contain solid particulates as contaminants, the orifice and nozzle includes an opening which is rectangular in a cross-sectional plane perpendicular to the axis of the fluid flow. The rectangular opening has a ratio of minimum width to minimum depth, or vice versa, of less than approximately 1.5, and preferably 1.0, and a ratio of the length of the opening to the lesser of minimum width and minimum depth of the opening of less than approximately 2.0, and preferably 1.0. The rectangular cross section together with these ratios prevents plugging by the solid contaminants.