Non-Steady Characteristics of Orifices

抄録

The non-steady characteristics of orifices have been analyzed on the assumption that the free streamline forms an ellipse on the hodogram. The coefficient of contraction is greater than that fro steady flow during the period of acceleration, and smaller during the period of deceleration. In sinusoidal pulsating flow, the mean value tends to be slightly smaller than the steady flow value. The opposite is true for the coefficient of discharge, defined by the instantaneous flow rate and the pressure difference. The experimental results, in which the amplitude of the pulsating flow rate was less than 0.5 and frequency less than 50 Hz, agreed well with the theoretical calculations.