In a reaction turbine both the nozzles and blades act as expanding nozzles. Therefore, the static pressure decreases in both the fixed and moving blades. The fixed blades
act as nozzles and direct the flow to the moving blades at a velocity slightly higher than the moving blade velocity
.
What is the purpose of the stationary nozzles in an impulse steam turbine?
An impulse turbine has fixed nozzles
that orient the steam flow into high speed jets
. These jets contain significant kinetic energy, which is converted into shaft rotation by the bucket-like shaped rotor blades, as the steam jet changes direction.
What are stationary blades?
Stationary blades are
installed or integrated in removable
stationary blade holders, diaphragms, or stationary blade rings, in order to facilitate cleaning during maintenance. Moving blades are installed in the rotor or disks.
What are the different functions of moving and fixed blades in reaction turbine?
The
fixed blades act as nozzles and accelerate the steam to a moderate velocity due to the partial pressure drop
. This steam then impinges upon the moving blades and imparts some energy to them. Within the moving blades the steam is turned and accelerated by the remainder of the pressure drop.
What is the function of the fixed blades in an impulse turbine?
The fixed blades are used
to guide the outlet steam/gas from the previous stage in such a manner so as to smooth entry at the next stage is ensured
. The fist stage in a large (power plant) turbine is velocity or pressure compounded impulse stage.
What is the difference between a blade and a vane?
Blades must operate at high rotating speeds and temperatures, while vanes direct the stream propelled by the rotating blades to the next turbine stage with optimum efficiency. Both blades and vanes must be
resistant to oxidation
, corrosion and wear, and provide longevity in service.
Why turbine blades are arranged in sequence?
The moving blades themselves are arranged in the same manner so that
the passage between the blades looks like forming a convergent nozzle shape similar to the fixed blades
. This particular design allows a small pressure drop and hence an increase in kinetic energy.
What is the purpose of the turbine?
A turbine is a device that
harnesses the kinetic energy of some fluid – such as water, steam, air, or combustion gases
– and turns this into the rotational motion of the device itself. These devices are generally used in electrical generation, engines, and propulsion systems and are classified as a type of engine.
What happens to the steam after passing through the turbine?
As that steam flows past a turbine’s spinning blades,
the steam expands and cools
. The potential energy of the steam is thus turned into kinetic energy in the rotating turbine’s blades.
Which is an example of impulse turbine?
Example:
Pelton wheel turbine
. Pelton Wheel Turbine: It is a tangential flow impulse turbine in which the pressure energy of water is converted into kinetic energy to form a high-speed water jet and this jet strikes the wheel tangentially to make it rotate.
What is the difference between impulse & reaction turbine?
What is the difference between the Impulse and Reaction Turbine? In an Impulse turbine,
All hydraulic energy is converted into kinetic energy by a nozzle
whereas In a Reaction turbine Only some amount of the available energy is converted into kinetic energy.
Where are reaction turbines used?
Reaction turbines are used in
wind power mills to generate electricity
. It is the most widely used turbine for generating electricity in hydroelectric plants.
What is fixed blade in turbine?
Steam Turbines
The fixed blades
act as nozzles
. The moving blades move as a result of the impulse of steam received (caused by a change in momentum) and also as a result of expansion and acceleration of the steam relative to them. In other words, they also act as nozzles (Figure 6.16).
Why it is called impulse turbine?
Unlike other types of turbines which are reaction turbines, the Pelton turbine is known as an impulse turbine. This simply means that
instead of moving as a result of a reaction force, water creates some impulse on the turbine to get it to move
.
What is the function of impulse turbine?
Impulse turbines
change the direction of flow of a high velocity fluid or gas jet
. The resulting impulse spins the turbine and leaves the fluid flow with diminished kinetic energy.
What happens in impulse turbine?
An impulse turbine is comprised of a stage of stationary nozzles followed by a stage of moving blades. In this turbine,
the potential energy of steam is converted into kinetic energy in nozzles
.
