Air-Water Mixture Flow Through Orfices, Bends, and other Fittings in a Horizontal Pipe

In planning piping systems for flow of gas-liquid mixtures, it is necessary to know something about the pressure and the pressure changes along the line. The pressure changes may be considered partly frictional and partly nonfrictional. Both of these mechanisms are active in mixture flows in straight, uniform pipes, and in fittings with gradual changes in cross section and/or alignment such as diffusers and bends. In fittings with abrupt changes in cross section, such as orifices, frictional losses are relatively small and pressure changes are largely the result of changes in kinetic energy and momentum. Furthermore, the flow pattern (that is, whether the flow be bubble, plug, annular, etc.) is dependent on the local pressure, other factors being constant, and it may be desirable to mow something about the flow pattern for use in heat transfer calculations, for example, and even for use in calculations for pressure drop in some fittings.