These impulse turbines are made up of rings of nozzles followed by rings of blades. Notably, high pressure, high energy steam is allowed into the nozzles then it is let into a region of lower pressure, high velocity in a different direction. As a result, the changing direction and high velocity produce impulsive force that acts in the direction of rotation of the turbines. Thus according to Newtons second law of motion, the rate of change in momentum is directly proportional to the external force producing the change and it takes place in the direction of the force (Woodruff 32).A notable feature of the Impulse turbine is the presence of fixed nozzles that orient the steam flow into high-speed jets (Wikipedia par. These jets contain significantly high kinetic energy which is transferred to the turbine to cause shaft rotation. A drop in pressure across the stationary blades with a net increase in steam velocity occurs. As a result, as the steam passes through the nozzles its pressure decreases from the inlet as it advances to the exit. As a result of the high ratio expansion of the steam, the steam leaves the nozzle at very high velocity and as such, a significant portion of maximum velocity in the steam leaves to the moving blades. Furthermore, the law of moment of momentum requires that moments of external forces acting on a fluid occupying the control volume be equal to the net time change of angular momentum flux through the control volume. The net loss in the energy due to the high exit velocity is commonly termed as carry over velocity useful in understanding the operation of the turbine (eHow par.The second type of steam turbines based on forces that act on them are the Reaction turbines. These turbines primarily apply Newton’s third law of motion that states that for every action force there is always reaction force. These type of turbines are made up of rings of fixed blades to the casing. A row of blades is tightly mounted on the rotor of the turbine (Woodruff par. These blades are shaped in such a way that they provide a narrowing passage which behaves like a nozzles. Therefore, increasing the velocity of steam it is important to notice that the increase in velocity of steam results in change in direction and an impulsive force is created and therefore the more correct name for this type of turbines is impulse- reaction because the two
eHow. “How a steam turbine works”, 2014. Web. 22 November, 2014.
www.ehow.com/how does_501161_how turbine-pumps- work.html
Wikipedia. “Steam turbine”, 17th November, 2014. Web. 22 November, 2014.
Woodruff, Everett B, Herbert B. Lammers, and Thomas F. Lammers. Steam Plant Operation. New York: McGraw-Hill, 2012. Print.
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