Higher Odd Harmonics Research Articles

Nonlinear Properties of Circular Orifices

The results of an experimental study of the nonlinear fluid flow properties of thin, square-edged, circular orifices are described. Liquids are used at low frequencies. The flow conditions considered are a sinusoidal oscillation of the fluid in the orifice and a sinusoidal oscillation with a steady component added. It is found that for the sinusoidal flow condition the pressure differential developed across the orifice contains higher odd harmonics. The addition of a steady flow component adds even harmonics to the pressure as well as influences the magnitude of the odd harmonics. In this case the steady pressure component is a function of the magnitude of both the sinusoidal and steady flow components. (This work was supported by the Office of Ordnance Research, Department of the Army, under Contract No. DA-23-072-ORD-583.)