Hydraulic turbines can be divided into impact turbines and impact turbines according to their working principles. The runner of the impact turbine is rotated by the impact of the water flow. The pressure of the water flow during the work is unchanged, mainly due to the conversion of kinetic energy. The runner of the impact turbine is rotated by the reaction force of the water in the water. The pressure of the water flow during the work Both energy and kinetic energy change, but mainly the conversion of pressure energy. The following is a detailed introduction of the Hydraulic Turbine Generator Supplier.
1. Impact turbine
Percussion turbines can be divided into two types according to the direction of the water flow: cut-type (also known as bucket type) and oblique type. The structure of the oblique impact turbine is basically the same as that of the bucket turbine, except that the jet direction has an inclination and is only used for small units.
Theoretical analysis proves that the efficiency is highest when the peripheral velocity at the bucket circle is about half of the jet velocity. When the load of this type of turbine changes, the direction of the water inlet speed of the runner does not change. In addition, these turbines are used in high-head power stations. The head change is relatively small and the speed change is small. Therefore, the efficiency is less affected by the load change , The efficiency curve is relatively smooth, the highest efficiency exceeds 91%.
2. Counterattack turbine
Impact turbines can be divided into mixed flow, axial flow, diagonal flow and cross flow. In mixed-flow turbines, the water flows radially into the water guiding mechanism and flows out of the runner axially; in axial-flow turbines, the water flows radially into the guide vanes and axially enters and leaves the runner; in diagonal flow turbines, the water flows Radially enter the guide vane and flow into the runner in a direction inclined to the main shaft, or flow into the guide vane and runner in a direction inclined to the main shaft; in a cross flow turbine, water flows into the guide vane in the axial direction And runner. Axial flow, cross flow and diagonal flow turbines can be further divided into fixed and rotary paddles according to their structure. Fixed paddle type runner blades are fixed; paddle type runner blades can be rotated around the blade axis during operation to adapt to changes in head and load.
(1) Axial flow turbine
Also known as Kaplan Turbine, it is suitable for lower head power stations. At the same head, the specific rotation speed is higher than that of the mixed flow turbine. The blades of the axial-flow fixed-paddle turbine are fixed on the runner body. The general installation height is 3-50m. The blade placement angle cannot be changed during operation, the structure is simple, and the efficiency is low. It is suitable for power stations with small load changes or by adjusting the number of generating units to adapt to load changes.
(2) Tubular turbine
The water flow between the guide vane and the runner of the cross-flow turbine is basically non-reversing. With the use of a straight cone tailpipe, the discharge does not have to turn in the tailpipe, so the efficiency is high, the flow capacity is large, and the ratio It is especially suitable for small riverbed power stations with low heads of 3 to 20 meters. This type of water turbine can be installed in a tidal power station to achieve bidirectional power generation. This type of turbine has various structures, and the most commonly used is a bulb type turbine.
(3) Francis turbine
Francis Turbine is also called Francis Turbine. Compared with the axial flow propeller type, the Francis Turbine has a simpler structure, stable operation, and the highest efficiency is higher than the axial flow type. Lower than the axial flow paddle type, the highest efficiency of this type of turbine is sometimes over 95%. Mixed-flow turbines have a wide range of heads, ranging from 5 to 700 meters, but the most widely used are 40 to 300 meters.
(4) oblique flow turbine
The blades of the oblique flow turbine are installed on the runner body obliquely. With the change of the water head and the load, the hydraulic pressure relay relay operating blade inside the runner body rotates correspondingly about its axis. Its highest efficiency is slightly lower than that of mixed-flow turbines, but the average efficiency is much higher than that of mixed-flow turbines. Compared with axial-flow propeller turbines, it has better anti-cavitation performance and lower flying speed, and is suitable for 40 to 120 meters.