The document discusses different types of nozzles used in steam turbines, including convergent, divergent, and convergent-divergent nozzles. It summarizes thermal modeling and analysis that was conducted to compare the erosion rates of three nozzle types: Moore nozzle, Moses and Stein nozzle, and convergent-divergent nozzle. The analysis found that the convergent-divergent nozzle had the highest velocity and comparatively minimum erosion rate, making it the best performing of the three nozzle types.

1. Applied Thermodynamics-1
Presented By -
Bijo Daniel (26)
Devesh Taori (27)
Dipesh Ahuja (28)
Gaurav Wadibhasme (29)
Harsh Sharma (30)

2.  A nozzle is a duct of smoothly varying cross
sectional area, in which a steadily flowing fluid can
be accelerated to a high velocity by a drop in
pressure of the fluid along the duct.
 The steam nozzle is a passage of varying cross-
section by means of which a part of the enthalpy
of steam is converted into kinetic energy as
the steam expands from a higher pressure to a
lower pressure.
 Therefore, a nozzle is a device designed to
increase the velocity of steam.

3.  The high pressure steam ejects out of the nozzle as high velocity fluid steam.
 The high velocity steam on hitting the blade of turbine suffers a loss of momentum
which rotates the turbine and results in production of torque.
 The blades move as a result of impulse of the steam caused by change of
momentum and also because of expansion and acceleration of steam.

4. TYPES OF
NOZZLE
CONVERGENT
DIVERGENT
CONVERGENT-DIVERGENT

5.  In a convergent nozzle, the cross sectional area decreases
continuously from its entrance to exit. It is used in a case where the
back pressure is equal to or greater than the critical pressure ratio.

6.  The cross sectional area of divergent nozzle increases continuously
from its entrance to exit. It is used in a case, where the back pressure is
less than the critical pressure ratio.

7.  In this case, the cross sectional area first decreases from its entrance to
throat, and then increases from throat to exit. It is widely used in many
type of steam turbines.

8. •Steam and Gas turbine
•Jet Engine
•Rocket Motors
•It is used to measure the discharge of fluid.- e.g. Venturi meter
•Injectors for pumping feed water to boilers.
•The supersonic gas turbine engine for the air intake
when the air requirement of the engine is high.
•Rockets: for providing sufficient thrust to move upwards.
•For removing air from the condenser using the injector.
•Steam jet refrigeration system

9.  Steam comes out of the nozzle
and on to the blades of the turbine
 The Kinetic energy possessed by the
steam is used to rotate the blades
 By rotation of the blades the drive
shaft rotates which is connected to a
generator

10.  The commonly used nozzle is manufactured by brass,
stainless steel, cast iron, bronze, tungsten carbide, nickel,
silicon carbide, super alloys, titanium, nickel alloys, tantalum.
 Coatings of ZrC , TiN , Cr3C2 , etc ., are also provided as a
protective measure to increase the life of the nozzle up to
its expected life

11. EROSION IN NOZZLE
Erosion is a degradation of material surface due to mechanical action, by
impinging liquid, abrasion by slurry, particles suspended in fast flowing fluids,
bubbles or droplets.
It can reduce efficiency and increase maintenance cost.
Although the use of protective coatings and anti-solid particle erosion (SPE)
steam passage design has improved the erosion resistance of the nozzle, the
nozzle life time is still shorter than the overall life of the steam turbine.

12. EROSION IN NOZZLE
 At present, repairing the eroded nozzle or replacing it with a new nozzle is the
most common method to recover the nozzle efficiency to the normal level
 As is well known, prolonging the service time of the eroded nozzle will lower the
unit efficiency and increase the fuel consumption, whereas shortening the
service time of the eroded nozzle will increase maintenance cost
 Therefore, a reasonable estimation of the economic lifetime of the eroded
nozzle is very critical for reducing the economic losses induced by SPE.

13.  Erosion usually caused by solid particles (usually iron oxide)
present in the steam.
 Erosion of intermediate and low-pressure blades is usually
caused by water in the steam.
 Operation below design inlet steam temperature or at low load
can cause condensation in these stages, leading to erosion
problems.
 Carbon dioxide or other acidic species present in the
condensate can accelerate the damage.

14.  Corrosion problems all occur in steam nozzle. The major corrodents are sodium
hydroxide, chloride, sulfate, and sulfides.
 As steam expands through a nozzle, the solubility of contaminants in the steam
decreases. They condense onto surfaces at solution concentrations much higher than
the original contaminant concentration in the steam. These concentrated solutions
promote system corrosion.
 An oxygen-free or condensate-free atmosphere should be maintained to protect from
corrosion.

15. Thermal Modeling and Analysis of High Pressure Steam
Turbine Outlet Nozzle
1) Moore Nozzle
2) Moses and Stein Nozzle
3) Convergent-Divergent Nozzle

16. Convergent-Divergent
Nozzle
Moore Nozzle
Moses and Stein Nozzle

17.  Software – ANSYS FLUENT
 Material – Bronze
 Fluid – Steam
 Impurity - Iron Oxide
 Inlet Velocity – 5 m/s
 Inlet pressure – 78000 Pascal

18. MOORE MOSES AND STEIN
CONVERGENT AND
DIVERGENT

19. MOORE
MOSES AND STEIN
CONVERGENT AND
DIVERGENT

20. MOORE MOSES AND STEIN
CONVERGENT AND
DIVERGENT

21. MOORE
MOSES AND STEIN
CONVERGENT AND
DIVERGENT

22. Type of nozzle Erosion Rate
(Kg/m2-s)
Velocity
(m/s)
Pressure
(Pa)
Temperature
(K)
Moore nozzle 0.385*e-24 7.0 -9.61*e1 350
Moses & Stein
nozzle
1.19*e-24 23.51 1.31*e5 350
Convergent and
Divergent nozzle
1.36*e-24 31.95 2.12*e5 300

23. CONCLUSION
The erosion rate is minimum
in Moore nozzle, but outlet
velocity is minimum when
compared with other
models.
Velocity is maximum in
convergent divergent
nozzle and erosion rate is
also comparatively
minimum.
Finally it is concluded that
among the three types of
nozzles convergent
divergent nozzle will gives
us better performance.
Type of
nozzle
Erosion
Rate
(Kg/m2-s)
Velocity
(m/s)
Pressure
(Pa)
Temperat
ure
(K)
Moore
nozzle
0.385*e-
24
7.0 -9.61*e1 350
Moses &
Stein
nozzle
1.19*e-24 23.51 1.31*e5 350
Converge
nt and
Divergent
nozzle
1.36*e-24 31.95 2.12*e5 300

24.  D. Kamalamma, D. Ramesh Babu, Thermal Modeling and Analysis of High
Pressure Steam Turbine Outlet Nozzle, International Research Journal of
Engineering and Technology (IRJET), June 2018, Volume: 05 Issue: 06
https://www.irjet.net/archives/V5/i6/IRJET-V5I632.pdf
 https://learnmech.com/what-is-steam-nozzle-types-of-steam-nozzle-shapes/