Image description

The image shows a Kaplan-type hydraulic turbine, named after its Austrian inventor, showed from side.

The Kaplan turbine is a machine with a rotor and adjustable blades, which rotates around an axis. transforming the hydraulic energy into mechanical energy, being used in the dams, where the flow of the river water is constant and the water fall is small, meaning it does not cross a relief with a large slope.

The turbine is mounted inside the basement of the hydropower plant, called the powerhouse, which is marked around the turbine by a grid texture.

The water currents in the middle are guided through the inlet guide vanes, from the left and right of the vertical driveshaft between the turbine and the generator, towards the turbine below, being highlighted by an arrow with the tip pointing towards the center.

The water is guided further into the lower part of the turbine, through a draft tube, represented by a contour of two parallel and thickened lines, separated by a blank space.

The rotor of the turbine, which drives the blades around it by rotation, is shown in the lower central part, embossed, in the shape of a domed triangle, with the rounded tip, called the nose cone, to the bottom.

The adjustable blades are rendered embossed, above the rotor, in the form of two small wings to the left and right of the rotor, the third being illustrated in the center, blank outlined.

Above the turbine is a long, narrow rod that leads up to the generator, called the vertical driveshaft , with the role of transmitting energy from rotation to the generator, being marked by a vertical and thickened line.

The generator is shown at the top, center, in the shape of a square domed at its top, with cut-out corners at the bottom, filled with dotted texture.

From here the energy transformed into electric current is modified by a transformer and transmitted to the energy distribution network through the high voltage power lines.

General information

The energy of the flowing water has been used for a very long time in order to serve different purposes. Such a purpose is the powering of water mills, as well as powering the electric generators from hydroelectric power plants. 

A hydraulic turbine is a mechanism that transforms the force of flowing water in a rotational movement. The part that collects the force of the water is a rotor with blades. The blades are a sort of arms with a special shape, which is optimal for collecting the force of the water, with minimal energy loss. The blades are attached around a rotor at regular intervals. The rotor is shaped as a circle.

The turbines turning the energy of flowing waters into a rotational movement are built in the dams for generating electric power. Dams are artificial blockings placed along water courses, in order to obtain an accumulation of water. The water gathered in a reservoir is directed towards the turbines of the hydroelectric power plant, but the mechanical force thus obtained is much bigger, compared with the free course of the water.

There are many types of hydraulic turbines among which we will mention:

  • The Pelton Turbine or Wheel, used in hydroelectric power plants with a high water head (meaning amount of falling water) and high water flow;
  • The Francis Turbine, used in hydroelectric power plants with medium water head;
  • The Kaplan Turbine, used in hydroelectric power plants with a low water head.

The Kaplan Turbine has a rotor with adjustable blades and it was invented in 1913 by Victor Kaplan, an Austrian engineer. This is an improved version of the Francis Turbine, which had energy losses, due to the air bubbles formed in the water flow. In order for the Kaplan Turbine to work properly, it needs a big, constant water flow, as well as a low water head. The biggest advantage of the Kaplan Turbine is its high efficiency, above 90%.

Did you know that The Iron Gates I and II (the two hydroelectric power plants placed on the gorge of the Danube River on the border between Romania and Serbia) use Kaplan Turbines? This type of turbine is the best for the water flow and fall conditions seen on the Danube: a big water flow with a low fall or head.


  1. https://ro.wikipedia.org/wiki/Turbin%C4%83_Kaplan
  2. https://ro.wikipedia.org/wiki/Turbin%C4%83_hidraulic%C4%83#Principii_de_baz%C4%83
  3. https://www.autogreen.ro/energie/turbina-kaplan/
  4. https://ro.wikipedia.org/wiki/Energie_cinetic%C4%83

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