Kaplan Turbine is a paddle-type turbine with variable blades. It was developed by Austrian professor Victor Kaplan in 1913. He combined self-adjusting propeller blades and self-adjusting guide vanes to achieve high productivity benefits on large drop flow and large head height differences.
The Kaplan turbine was first evolved from the Francis turbine. His invention can be used to efficiently generate electricity in hydropower plants with extremely low head heights, but extremely low head heights are not possible for Francis turbines. The design head height range is 10-70 meters, and the output can be from 5 to 200 MW. The diameter of the moving wheel is between 2 and 11 meters. The speed range is from 79 to 429 rpm. Kaplan Turbine and its matching generator have a theoretical head height of 34.65 meters for the highest power generation efficiency. It is the Kaplan turbine with a diameter of 4.8 meters in the ten channels in the Tacoma Power Plant in Venezuela in 2013. It is 235MW. Kaplan turbines are now widely used in high-flow, low-head hydraulic power plants.
Kaplan turbines are a type of internal-flow counter-turbines, which means that after the working fluid flows into the turbine, the fluid pressure changes and energy is lost. Energy is obtained from both the head and the kinetic energy of the current. This type of turbine design combines the functions of radial and axial turbines.
The fluid inlet is a vortex-shaped pipeline and surrounds the turbine vane. After flowing into the turbine, the fluid will flow tangentially to the Guide Vanes and spirals, and pass through the propeller-type moving wheels to rotate them. The fluid outlet is a special-shaped guide tube, which helps to slow down the flow rate of the fluid and recover the kinetic energy.
The installation location of Kaplan turbine does not need to be at the lowest point of the water flow, only the drainage pipe needs to be kept full of water to be set. However, a higher installation location may cause the turbine blades to be drawn into the draft tube, and the resulting pressure drop may cause cavitation.
The variable side doors and turbine blades allow the turbine operator to perform various and effective control of various water flow conditions. Under normal conditions, Kaplan turbines can run at over 90% efficiency, but may only be used at very low head heights.
Current research areas include improvements in computational fluid dynamics (CFD) driving efficiency and new designs, as well as improving the survival rate of fish as they pass through the turbine.
Because earlier, when Kaplan designed the Kaplan turbine, its propeller blade rotation must rely on the high-pressure hydraulic oil on the bearing to keep it smooth, and the high-pressure hydraulic oil must be kept in an extremely sealed state to prevent the tail When water flows into the river, such a situation is undesirable, because it will not only cause waste of resources, but also cause serious environmental pollution.