Types of turbine blades
Introduction:-
The function of turbine is drive the
compressor and accessories, and, in the case of the turboprop, the propeller,
by extracting a portion of the pressure and kinetic energy from the high-temperature
combustion
gases.
In a typical Jet engine, about 75% of the
power produced internally is used to drive the compressor.
Turbines:-
A portion of the kinetic energy of the
expanding gases is extracted by the turbine section, and this energy is
transformed into shaft horsepower which is used to drive the compressor and
accessories. In turboprop and turbo shaft engines,
additional turbine rotors are designed to extract all of the energy possible
from the remaining gases to drive a power shaft.
A Turbine is a device which converts the
heat energy of steam into the kinetic
energy & then to rotational energy
Types
Of Turbine Blade:-
ØImpulse
ØReaction
ØImpulse reaction
Impulse:-
•Impulse
machine are those in which there is no change of static or pressure head of the
fluid in the rotor.
•The
rotor blades cause only energy transfer and there is no energy transformation.
•Energy
transformation takes placed in fixed blades only.
•Transfer
of K.E to the rotor in an impulse turbine from high velocity fluid occurs only
due to the impulsive actions of the fluid on the rotor.
Reaction:-
•Reaction
machines are those, in which changes in static or pressure head occurs both in
stator and rotor blade passages.
•The
energy transformation occurs both in fixed as well as moving blade
•The
rotor experience both energy transfer as well as energy transformation.
•The
degree of reaction of turbomachine stage may be defined as ratio of static or
pressure head occurring in rotor to the total change across the stages
Impulse
reaction:-
it is combination of both Impulse and Reaction
Difference
Between Impulse & Reaction
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Impulse
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qDuring flow of steam pressure drop only in the nozzle
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qBlades are profile type
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qPower developed is comparatively less
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qBlades arne symmetrical
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qNo.of stages required
for given
power is less
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