Editing Two-phase flow (section)

== Examples and applications ==
Historically, probably the most commonly studied cases of two-phase flow are in large-scale power systems. Coal and gas-fired power stations used very large [[boiler]]s to produce steam for use in [[turbine]]s. In such cases, pressurised water is passed through heated pipes and it changes to steam as it moves through the pipe. The design of boilers requires a detailed understanding of two-phase flow heat-transfer and pressure drop behaviour, which is significantly different from the single-phase case. Even more critically, [[nuclear reactor]]s use water to remove heat from the reactor core using two-phase flow. A great deal of study has been performed on the nature of two-phase flow in such cases, so that engineers can design against possible failures in pipework, loss of pressure, and so on (a [[loss-of-coolant accident]] (LOCA)).<ref name=levy>Salomon Levy, Two-Phase Flow in Complex Systems, Wiley, 1999</ref>

Another case where two-phase flow can occur is in pump [[cavitation]]. Here a pump is operating close to the [[vapor pressure]] of the fluid being pumped. If pressure drops further, which can happen locally near the vanes for the pump, for example, then a phase change can occur and gas will be present in the pump. Similar effects can also occur on marine propellers; wherever it occurs, it is a serious problem for designers. When the vapor bubble collapses, it can produce very large pressure spikes, which over time will cause damage on the propeller or turbine.

The above two-phase flow cases are for a single fluid occurring by itself as two different phases, such as steam and water. The term 'two-phase flow' is also applied to [[mixture]]s of different fluids having different phases, such as air and water, or oil and natural gas. Sometimes even ''three''-phase flow is considered, such as in oil and gas pipelines where there might be a significant fraction of solids.  Although oil and water are not strictly distinct phases (since they are both liquids) they are sometimes considered as a two-phase flow; and the combination of oil, gas and water (e.g. the flow from an offshore oil well) may also be considered a three-phase flow.

Other interesting areas where two-phase flow is studied includes water [[electrolysis]],<ref>{{Cite journal|first=Colli A.N.|last=Bisang J.M.|title=Current and Potential Distribution in Two-Phase (Gas Evolving) Electrochemical Reactors by the Finite Volume Method|journal=Journal of the Electrochemical Society|year=2022|volume=169|issue=3|pages=034524|doi=10.1149/1945-7111/ac5d90|bibcode=2022JElS..169c4524C|s2cid=247463029}}</ref> climate systems such as [[cloud]]s,<ref name=levy/> and in [[groundwater]] flow, in which the movement of water and air through the soil is studied.

Other examples of two-phase flow include [[liquid bubble|bubble]]s, [[rain]], [[wave]]s on the [[sea]], [[foam]], [[fountain]]s, [[mousse]], [[cryogenics]], and [[oil slick]]s. One final example is in the electrical explosion of metal.