Hydro Francis Hydro Low Rpm Generator River Water Turbine Hydropower

The Francis turbine has a compact structure, high efficiency, and can adapt to a wide range of water heads. It is one of the types of turbines widely used in countries around the world. When the water flow passes through the turbine wheel, it enters in the radial direction and flows out in the axial direction, so it is also called radial axial turbine.
It is suitable for water heads ranging from 20 meters to 700 meters. The mechanism is simple, the operation is stable, and the efficiency is high, but it is generally used in the range of medium heads (50 meters to 400 meters). The output of a single machine ranges from tens of kilowatts to hundreds of thousands of kilowatts. At present, the maximum output of this turbine has exceeded 700,000 kilowatts.

Francis Turbine Components

1. Spiral Casing
Spiral casing is the inlet medium of water to the turbine. The water flowing from the reservoir or dam is made to pass through this pipe with high pressure. The blades of the turbines are circularly placed, which mean the water striking the turbines blades should flow in the circular axis for efficient striking. So the spiral casing is used, but due to circular movement of the water, it looses its pressure.

To maintain the same pressure the diameter of the casing is gradually reduced, so as to maintain the pressure uniform, thus uniform momentum or velocity striking the runner blades.

2. Stay Vanes
Stay vanes and guide vanes guides the water to the runner blades. Stay vanes remain stationary at their position and reduces the swirling of water due to radial flow, as it enters the runner blades. Thus making turbine more efficient.

3. Guide Vanes
Guide vanes are not stationary, they change their angle as per the requirement to control the angle of striking of water to turbine blades to increase the efficiency. They also regulate the flow rate of water into the runner blades thus controlling the power output of a turbine according to the load on the turbine.

4. Runner Blades
The performance and efficiency of the turbine is dependent on the design of the runner blades. In a Francis turbine, runner blades are divided into 2 parts. The lower half is made in the shape of small bucket so that it uses the impulse action of water to rotate the turbine.

The upper part of the blades use the reaction force of water flowing through it. These two forces together makes the runner to rotate.

5. Draft Tube
The pressure at the exit of the runner of Reaction Turbine is generally less than atmospheric pressure. The water at exit cannot be directly discharged to the tail race. A tube or pipe of gradually increasing area is used for discharging water from the exit of turbine to the tail race.

This tube of increasing area is called Draft Tube. 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.

Pelton Turbine Generator Product parameters