A Theoretical Approach to Two-Phase Critical Flow : (5th Report, Several Problems on Discharging of Saturated Water through Orifices)

Abstract

Saturated water discharging through orifices is theoretically and experimentally studied and the following results are obtained. (1) Saturated critical flow through frictionless channel can be easily treated by combining critical condition with such upstream parameters as static pressure and steam quality, and this method can be applied to predicting of discharging rate of saturated water through orifice except the cases where thermodynamical metastability is established. (2) Ratio between back pressure and upstream pressure is not invariable, but this seems to form one of flow conditions. (3) The magnitudes of orifice diameter and upstream pressure which can be treated by traditional orifice constant of around 0.6 are in a considerably wide range. (4) In the case when orifice flow rate is calculated as homogeneous flow, orifice constant seems to converge around 0.4 as for large orifice size and high upstream pressure. (5) The flow rate through orifice varies with a decreasing back pressure until the critical condition is reached.