Jet

See also jet (lignite), JET (Japanese English Teacher) and Jet, a rock band from Melbourne, Australia, Blue jet, a form of upper atmospheric lightning, Jet (comic), JET (Joint European Torus)

A jet is a stream of fluid produced by discharge through an orifice into free space.

Since gases are compressible fluids, the velocity attained by a jet of gas cannot be determined by Bernoulli's principle. Instead, if one uses adiabatic expansion from P₁ to P₂ in a properly shaped nozzle, the ideal velocity of a gas jet is:

<math>v=8\sqrt{(RT_1/z) (1-(P_2/P_1)^z)} <math>

where R and z are characteristics of the gas, R being the common gas constant and z being (c_p − c_v)/c_p, where the cs are the specific heat at constant pressure and constant volume, respectively. z = 0.286 for air under 500 °C. z = 0.23 to 0.28 for most combustion products of fuels. T₁ is the absolute temperature at pressure P₁.

See jet engine and jet aircraft.