Editing Injector (section)

====Nozzle====
[[File:Kneass15steamDischarge.png|thumb|right|Kneass's illustrations of differently shaped steam nozzles]]
Figure 15 shows four sketches Kneass drew of steam passing through a nozzle.  In general, [[compressible flow]]s through a diverging duct increase velocity as a gas expands.  The two sketches at the bottom of figure 15 are both diverging, but the bottom one is slightly curved, and produced the highest velocity flow parallel to the axis.  The area of a duct is proportional to the square of the diameter, and the curvature allows the steam to expand more linearly as it passes through the duct.

An [[ideal gas]] cools during [[adiabatic]] expansion (without adding heat), releasing less energy than the same gas would during [[isothermal]] expansion (constant temperature).  Expansion of steam follows an intermediate [[thermodynamic process]] called the [[Rankine cycle]].  Steam does more [[Work (thermodynamics)|work]] than an ideal gas, because steam remains hot during expansion.

The extra heat comes from [[enthalpy of vaporization]], as some of the steam condenses back into droplets of water intermixed with steam.<ref name="k1910"/>