PDF | Impulse turbine has been constructed to be used in the program of Hydraulic Machines, Faculty of Mechanical Engineering at the. The purpose of this experiment is to revise the concepts of turbine cycle, its practical is classified as a “simple, single stage, axial flow, impulse turbine”. The impulse shows the total result of applying force. Impulse turbine works on the same principle. It is mostly used at high heads. Today we will.
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existing impulse turbine, a one-stage turbine set in an organic Rankine cycle fepipvawoobig.cf Turbine blades, and hence turbines having these types of blades, are classified as impulse or reaction. When moving blades are driven entirely by the impact of. “Turbine” is a general term for any device that extracts mechanical energy from a There are two main types of dynamic turbines: impulse turbines and reaction.
The effect of this change in direction of the steam flow will produce an impulse force. This force cause the blade move, thereby the rotor will start to rotate.
The change of momentum produces the impulse force. Impulse Turbine Working: In the impulse turbine pressure drops and the velocity increases as the steam passes through the nozzles.
When the steam passes through the moving blades the velocity drops but the pressure remains the same. The fact that the pressure does not drop across the moving blades is the distinguishing feature of the impulse turbine. The pressure at the inlet of the moving blades is same as the pressure at the outlet of moving blades.
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.
Compounding of steam turbines
This force will make the blades to rotate. Reaction Turbine Working: A reaction turbine has rows of fixed blades alternating with rows of moving blades.
The steam expands first in the stationary or fixed blades where it gains some velocity as it drops in pressure. Then enters the moving blades where its direction of flow is changed thus producing an impulse force on the moving blades.
In addition, however, the steam upon passing through the moving blades, again expands and further drops in pressure giving a reaction force to the blades. This sequence is repeated as the steam passes through additional rows of fixed and moving blades. Note that the steam pressure drops across both the fixed and the moving blades while the absolute velocity rises in the fixed blades and drops in the moving blades. The distinguishing feature of the reaction turbine is the fact that the pressure does drop across the moving blades.
The force exerted on blades depends upon amount of change in direction of jet. So the blades are generally concave in shape. Rotor: Rotor which is also known as wheel is situated on the shaft. All blades are pined into the rotor.
The force exerted on blades passes to the rotor which further rotates the shaft. Nozzle: A nozzle play main role of generating power from impulse turbine.
It is a diverging nozzle which converts all pressure energy of water into kinetic energy and forms the water jet. This high speed water strikes the blades and rotates it.
Casing: Casing is the outside are which prevent the turbine form atmosphere. The main function of casing is to prevent discharge the water from vanes to tail race.
There is no change in pressure of water from nozzle to tail race so this turbine works at atmospheric pressure. Braking nozzle: A nozzle is provided in opposite direction of main nozzle. It is used to slow down or stop the wheel.
Working: As we discussed impulse turbine works on basic principle of impulse. Its working can be describe in following points.The steam passes over a series of alternate fixed and moving blades.
For better understanding watch the video given below on working of impulse turbine. Starboard steam turbine machinery arrangement of Japanese Furutaka- and Aoba-class cruisers. The law of moment of momentum states that the sum of the moments of external forces acting on a fluid which is temporarily occupying the control volume is equal to the net time change of angular momentum flux through the control volume.
Induction turbines introduce low pressure steam at an intermediate stage to produce additional power.