Abstract
The flow of hot water, with saturation pressure above the downstream pressure, through orifices or nozzles depends largely upon the nature of the expansion of the fluid and the confinement of the expansion by the orifice or nozzle. Intermolecular forces as influenced by surface tension tend to metastabilize the initial liquid phase to a corresponding subsaturated pressure. These forces also tend to metastabilize the droplets formed in steam at the critical size corresponding to the critical pressure at expansion. The influence of orifice or nozzle form on the expansion process for initially stable and metastable entering fluid is analyzed with confirming test data interpreted from the intermediate-pressure measurements between two identical orifices in series. Control effects obtainable with change of the intermediate pressure between two orifices as determined by the thermal state of the fluid are briefly discussed and a new practical application form of such a control element as applied to condensate removal from steam systems is described. Attention is directed toward new avenues for further investigation in this field.
