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.)