The mixed flow turbine generator, also known as the Francis type turbine,is a kind of counterattack turbine. It was invented by American engineer Francis in 1849. It is also called the Francis water turbine or the radial flow turbine. The Francis turbine is simple in structure. Its main components include spiral case, seal ring, water guiding mechanism, top cover, runner, spindle, guide bearing, bottom ring and draft tube. The volute is a water diversion component,resembling a snails shell, usually made of metal material, with circular cross section.. The seat ring is placed between the spiral case and the guide leaf, which is made up of the upper ring, the lower ring and a number of column is wing shaped, not rotated, also known as a fixed guide leaf. The water guiding mechanism is composed of a movable guide blade, a speed regulating ring, a crank arm and a connecting rod. The wheel is directly connected with the spindle, which is the rotating part of the type of water turbine. The runner consists of the upper crown, the lower ring, the discharge cone and a number of fixed blades. The mataching dimensions of the shape and the components are different according to the different water heds they use. The draft tube is the discharge part of the hydraulic turbine which leads the flow of the runner outlet to the downstrem. Generally, it is curved elbow. The small water turbine is usually used in a straight conical draft pipr. The flow of water flows from the radial direction to the wheel, and then the rotating wheel is approximately in the direction of the axial flow. The trend of development in recent years is high head, large capacity, high specific speed and high efficiency. The Francis turbine generator set produced by our factory mainly has two horizontal and vertical models.Characteristics
1. The Francis turbine has a compact structure, high efficiency, and can be adapted to a wide water head.It is one of the most widely used hydraulic turbines in the world.
2. When the water passes through the working wheel of the hydraulic turbine, it enters and flows out in a radial direction. So it is also called a radial axial flow turbine.
3. The flow of water flows from the radial direction to the wheel, and then approximately the axial flow wheel. The runner consists of the upper crown, the lower ring and the blade.
4. It is suitable for the water head fom 20 meters to 700meters, the mechanism is simple, the operation is stable and the efficiency is high, but it is generally used in the range of middle water head(50 meters to 400meters).The single machine foce from dozens of kilowatts to tens of thousands of watts. At present, the maximum output of this turbine has exceeded 700 thousand kilowatts. It is one of the most widely used hydraulic turbines.