Sunday, May 17, 2009

Kaplan turbine

From Wikipedia, the free encyclopedia

  (Redirected from Kaplan Turbine)
Bonneville Dam Kaplan turbine after 61 years of service

The Kaplan turbine is a propeller-type water turbine that has adjustable blades. It was developed in 1913 by the Austrian professor Viktor Kaplan.

The Kaplan turbine was an evolution of the Francis turbine. Its invention allowed efficient power production in low-head applications that was not possible with Francis turbines.

Kaplan turbines are now widely used throughout the world in high-flow, low-head power production.




Viktor Kaplan living in BrnoMoravia, now Czech Republic, obtained his first patent for an adjustable blade propeller turbine in 1912. But the development of a commercially successful machine would take another decade. Kaplan struggled with cavitation problems, and in 1922 abandoned his research for health reasons.

In 1919 Kaplan installed a demonstration unit at PodÄ›bradyCzechoslovakia. In 1922 Voith introduced an 1100 HP (about 800 kW) Kaplan turbine for use mainly on rivers. In 1924 an 8 MW unit went on line at Lilla EdetSweden. This marked the commercial success and wide spread acceptance of Kaplan turbines.

[edit]Theory of operation

Vertical Kaplan Turbine (courtesy Voith-Siemens).

The Kaplan turbine is an inward flow reaction turbine, which means that the working fluid changes pressure as it moves through the turbine and gives up its energy. The design combines radial and axial features.

The inlet is a scroll-shaped tube that wraps around the turbine's wicket gate. Water is directed tangentially through the wicket gate and spirals on to a propeller shaped runner, causing it to spin.

The outlet is a specially shaped draft tube that helps decelerate the water and recover kinetic energy.

The turbine does not need to be at the lowest point of water flow, as long as the draft tube remains full of water. A higher turbine location, however, increases the suction that is imparted on the turbine blades by the draft tube. The resulting pressure drop may lead to cavitation.

Variable geometry of the wicket gate and turbine blades allow efficient operation for a range of flow conditions. Kaplan turbine efficiencies are typically over 90%, but may be lower in very low head applications.

Current areas of research include CFD driven efficiency improvements and new designs that raise survival rates of fish passing through.

Because the propeller blades are rotated by high-pressure hydraulic oil, a critical element of Kaplan design is to maintain a positive seal to prevent emission of oil into the waterway. Discharge of oil into rivers is not permitted.


Kaplan turbines are widely used throughout the world for electrical power production. They cover the lowest head hydro sites and are especially suited for high flow conditions.

Inexpensive micro turbines are manufactured for individual power production with as little as two feet of head.

Large Kaplan turbines are individually designed for each site to operate at the highest possible efficiency, typically over 90%. They are very expensive to design, manufacture and install, but operate for decades.


The Kaplan turbine is the most widely used of the propeller-type turbines, but several other variations exist:

Propeller turbines have non-adjustable propeller vanes. They are used in where the range of head is not large. Commercial products exist for producing several hundred watts from only a few feet of head. Larger propeller turbines produce more than 100 MW.

Bulb or Tubular turbines are designed into the water delivery tube. A large bulb is centered in the water pipe which holds the generator, wicket gate and runner. Tubular turbines are a fully axial design, whereas Kaplan turbines have a radial wicket gate.

Pit turbines are bulb turbines with a gear box. This allows for a smaller generator and bulb.

Straflo turbines are axial turbines with the generator outside of the water channel, connected to the periphery of the runner.

S- turbines eliminate the need for a bulb housing by placing the generator outside of the water channel. This is accomplished with a jog in the water channel and a shaft connecting the runner and generator.

VLH turbine an open flow, very low head "kaplan" turbine slanted at an angle to the water flow. It has a large diameter, is low speed using a permanent magnet alternator with electronic power regulation and is very fish friendly (<5% href="" class="external text" title="" rel="nofollow" style="text-decoration: none; background-image: url(; background-repeat: no-repeat; background-attachment: initial; -webkit-background-clip: initial; -webkit-background-origin: initial; background-color: initial; padding-top: 0px; padding-right: 13px; padding-bottom: 0px; color: rgb(51, 102, 187); padding-left: 0px; background-position: 100% 50%; ">VLH Turbine

Tyson turbines are a fixed propeller turbine designed to be immersed in a fast flowing river, either permanently anchored in the river bed, or attached to a boat or barge.

Vertical Kaplan Turbine (courtsey VERBUND-Austrian Hydro Power).
Horizontal Bulb turbine. (courtsey VERBUND-Austrian Hydro Power).

Francis turbine

From Wikipedia, the free encyclopedia

Francis turbine (courtesy Voith-Siemens)

The Francis turbine is a type of water turbine that was developed by James B. Francis. It is an inward flow reaction turbine that combines radial and axial flow concepts.

Francis turbines are the most common water turbine in use today. They operate in a head range of ten meters to several hundred meters and are primarily used for electrical power production.




Francis turbine parts
Francis Runner, Grand Coulee Dam

Water wheels have been used historically to power mills of all types, but they are inefficient. 19th century efficiency improvements of water turbines allowed them to compete with steam engines (wherever water was available).

In 1826 Benoit Fourneyron developed a high efficiency (80%) outward flow water turbine. Water was directed tangentially through the turbine runner causing it to spin. Jean-Victor Poncelet designed an inward-flow turbine in about 1820 that used the same principles. S. B. Howd obtained a U.S. patent in 1838 for a similar design.

In 1848 James B. Francis improved on these designs to create a turbine with 90% efficiency. He applied scientific principles and testing methods to produce the most efficient turbine design ever. More importantly, his mathematical and graphical calculation methods improved the state of the art of turbine design and engineering. His analytical methods allowed confident design of high efficiency turbines to exactly match a site's flow conditions.

[edit]Theory of operation

The Francis turbine is a reaction turbine, which means that the working fluid changes pressure as it moves through the turbine, giving up its energy. A casement is needed to contain the water flow. The turbine is located between the high pressure water source and the low pressure water exit, usually at the base of a dam.

The inlet is spiral shaped. Guide vanes direct the water tangentially to the runner. This radial flow acts on the runner vanes, causing the runner to spin. The guide vanes (or wicket gate) may be adjustable to allow efficient turbine operation for a range of water flow conditions.

As the water moves through the runner its spinning radius decreases, further acting on the runner. Imagine swinging a ball on a string around in a circle. If the string is pulled short, the ball spins faster. This property, in addition to the water's pressure, helps inward flow turbines harness water energy.

At the exit, water acts on cup shaped runner features, leaving with no swirl and very little kinetic or potential energy. The turbine's exit tube is shaped to help decelerate the water flow and recover the pressure.


Francis Inlet Scroll, Grand Coulee Dam
Small swiss-made Francis turbine

Large Francis turbines are individually designed for each site to operate at the highest possible efficiency, typically over 90%.

Francis type units cover a wide head range, from 20 meters to 700 meters and their output varies from a few kilowatt to 1,000 megawatt.

In addition to electrical production, they may also be used for pumped storage; where a reservoir is filled by the turbine (acting as a pump) during low power demand, and then reversed and used to generate power during peak demand.

Francis turbines may be designed for a wide range of heads and flows. This, along with their high efficiency, has made them the most widely used turbine in the world.