Jet
- For alternative meanings, see Jet (disambiguation).
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>
- R is the common gas constant
- T1 is the absolute temperature at pressure P1
- z is <math>\begin{matrix}{c_p – c_v \over c_p}\end{matrix}<math>
- cp is the specific heat at constant pressure
- cv is the specific heat at constant volume
- z = 0.286 for air under 500 °C
- z = 0.23 to 0.28 for most combustion products of fuels
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