Steam Nozzles

The steam nozzle is a passage of varying cross section by means of which the thermal energy of steam is converted into kinetic energy. The shape of the nozzle is designed such that it will perform this conversion of energy with minimum losses continuity equation is used for designing produce a jet of steam of high velocity for the purpose of driving steam turbine. When steam f lows through a nozzles expansion process take place. As the steam expand there is drop in pressure and enthalpy of steam and consequently its velocity and specific volume both increases .The smalls section of the nozzle is known as throat.
Types of nozzles:
There are two types:
1-Convergent nozzle. (fig.(1))
2-Convergent-Divergent nozzle.(fig.(2))

fig.(2)
fig.(1)



Variation of specific volume, area and velocity:
1-Velocity:except for the first part of the nozzle, the velocity increases at almost constant rate.
2-specific volume :for a considerable part of expansion ,the specific volume increases gradually. However during the latter part of the expansion. The specific volume increases very rapidly.
3-Area: