History Of The Construction Of Hoover Dam

Construction of the Hoover Dam began in 1931. Its main purpose was for flood control, irrigation, and to provide hydroelectric power to many communities throughout the southwestern United States. There are 17 main turbines in the Hoover Dam power plant; consisting of nine on the Arizona side and 8 on the Nevada side. The generators which were to provide and generate electricity to this region were Francis-turbine generators. Since 1947, the average annual net generation for Hoover Power plant was approximately 4.2 billion kilowatt-hours. The Francis-turbine generator was developed by James B. Francis in Massachusetts in 1848. It is the first inward flow reaction turbine. It operates in water head between 130 to 2,000 feet with speeds ranging

The casing has openings at regular intervals to allow the working fluid to impound the blades of the runner. Guide vanes direct the water to the turbine wheel, known as a runner. This radial flow acts on the runner's vanes, causing the runner to spin. The water enters the turbine through the outer periphery of the runner in a radial direction and leaves the runner in an axial direction, hence “mixed flow turbine”. It is a reaction turbine and only a part of the available head is converted into the velocity head before water enters the runner. The pressure head decreases as the water flows over the runner blades. The static pressure at the runner exit may be less than the atmospheric pressure and as such, water fills all the passages of the runner blades. The change in pressure while water is moving over the blades is called “reaction pressure” and is partly responsible for the rotation of the

One end of the tube is connected to the outlet of runner while the other end is sub-merged below the level of water in the tail-race. Another function of the Draft Tube is to reduce the effect of cavitation by transforming the velocity head to static head due to its increasing area therefore, reducing the effect of cavitation. Cavitation can be reduced by optimizing the pressure distribution on the blades to avoid areas of high relative velocities. In addition the setting level for of the turbine relative to the tailwater can be reduced or the turbine can be designed with larger diameter and lower flow velocities.

All in all, the Francis Turbine is a very efficient turbine that was ahead of its time when the Hoover dam was built. The Francis Turbine has a long history, with experience gained from past designs, and technological advances; the Francis Turbine is the most popular turbine used in the world. In modern day, it is used in many of the world’s most efficient dams, such as the Three Gorges Dam in China, the Itaipu Dam in Brazil, and the most recent, Xiluodu Dam in