There are two basic types of steam turbines: impulse turbines and reaction turbines. Impulse turbines have fixed nozzles that expand steam at constant pressure, while reaction turbines have expanding nozzles in both fixed and moving components, allowing continuous expansion of steam as it flows over blades. Impulse turbines work by directing high velocity steam from stationary nozzles against rotating buckets, while reaction turbines generate rotation from the reaction force of steam pressure decreasing as it passes through shaped, moving blades.

1. Steam turbines may be classified into
different categories depending on their
construction, working pressures, size and
many other parameters. But there are two
basic types of steam turbines:
impulse turbines
reaction turbines.

2. IMPULSE TURBINE
• The impulse turbine is composed of moving blades alternating
with fixed nozzles. In the impulse turbine, the steam is expanded in
fixed nozzles and remains at constant pressure when passing over the
blades. Curtis turbine, Rateau turbine, or Brown-Curtis turbine are
impulse type turbines. The original steam turbine, the De Laval, was
an impulse turbine having a single-blade wheel.

3. REACTION TURBINE
• The reaction turbine is composed of moving blades (nozzles)
alternating with fixednozzles. In the reaction turbine, the steam is
expanded in fixed nozzles and also in the moving nozzles. In other
words, the steam is continually expanding as it flows over the blades.
There is pressure and velocity loss in the moving blades. The moving
blades have a converging steam nozzle. Hence when the steam passes
over the fixed blades, it expands with decrease in steam pressure and
increase in kinetic energy.

4. How impulse turbine work
• Impulse Turbine
• In principle, the impulse steam turbine consists of a casing containing
stationary steam nozzles and a rotor with moving or rotating buckets.
• When the steam passes through the stationary nozzles and is directed
at high velocity against the rotor buckets. The rotor buckets starts to
rotate at high speed.

5. How reaction turbine work
• Reaction Turbine Principle:
• In the case of reaction turbine, the moving blades of a turbine are
shaped in such a way that the steam expands and drops in pressure
as it passes through them. As a result of pressure decrease in the
moving blade, a reaction force will be produced. This force will make
the blades to rotate.

6. Impulse turbine reaction turbine