Types of water turbines:

As water sources vary, water turbines have been designed to suit the different locations. The three main types are Pelton wheels, Francis turbines, and Kaplan or propeller type turbines (named after their inventors). All can be mounted vertically or horizontally. The Kaplan or propeller type turbines can be mounted at almost any angle, but this is usually vertical or horizontal.

To view diagrams of these three turbines, go to
“types of wind turbines” at:
http://en.wikipedia.org/wiki/Water_turbine

• The Pelton wheel is used where a small flow of water is available with a “large head”. It resembles the waterwheels used at water mills in the past. The Pelton wheel has small “buckets” all around its rim. Water from the dam is fed through nozzles at very high speed, hitting the buckets and pushing the wheel around.

Above - The Pelton wheel from the hydro power station in Walchensee, Germany.

• The Francis turbine is used where a large flow and a high or medium head of water is involved. The Francis turbine is also similar to a waterwheel in that it looks like a spinning wheel with fixed blades in between two rims. This wheel is called a “runner”. A circle of guide vanes surrounds the runner and controls the amount of water driving it. Water is fed to the runner from all sides by these vanes causing it to spin.

Above - The Francis turbine at the Francis Inlet Scroll, Grand Coulee Dam, in Washington USA.

• Propeller type turbines are designed to operate where a small head of water is involved. These turbines resemble ship’s propellers. However, with some of these (such as Kaplan turbines) the angle (pitch) of the blades can be altered to suit the water flow. The variable pitch feature permits the machine to operate efficiently over a range of heads, to allow for the seasonal variation of water levels in a dam.

Above - A propeller-type runner rated 28,000hp or horsepower, which is the equivalent of 20.880 kilowatts.

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