Water turbine is one of the most commonly used equipment in power stations, so what is the role of the guide vanes? Hydraulic Turbine Generator Supplier will tell you next.
The guide vane is the energy transfer device of the centrifugal pump. Its function is to collect the liquid thrown out by the impeller to reduce the flow velocity of the liquid. After converting part of the speed energy head to pressure energy head, it is evenly introduced into the next stage or passed The diffusion tube is discharged. The guide vane has the same function as the volute, and is mostly used in segmented multistage pumps. In a multi-stage centrifugal pump, the guide vanes are mounted in the middle section with a partition.
Guide vanes can be divided into radial guide vanes and runner guide vanes according to their structural forms. The front and back guide vanes of the runner-type guide vane are cast together, and there is a continuous flow passage in the middle, which makes the liquid flow in the continuous flow passage, and it is difficult to form dead angles and sudden diffusion. The speed changes are more uniform and the hydraulic performance is better. But the structure is complex and the manufacturing process is poor.
Guide vanes are mostly used in hydraulic machinery for backflow situations, such as Kaplan Turbine's movable guide vanes, fixed guide vanes, and guide vanes in pumps. Their role is to generate ring volume (fixed guide vanes can also generate part of the ring volume. Many academic circles may not yet accept this function of fixed guide vanes.
Now let us explain why the axial flow pumps have not reached the ideal state, even when the number of blades is infinite. In fact, the reason is that the reverse flow of the guide vanes is not very good, and it is in the middle of the leaf channel. Vane vortices are generated, which is equivalent to the presence of axial swirling sockets in a centrifugal pump, which affects the lift.
The guide vane is one of the most important castings and forgings in the water guide mechanism of a hydro-generator set, and its manufacture has always been a major problem in the manufacture of large hydro-turbine units. In the past, guide vanes were mostly produced by sand casting. The internal quality of the casting was unstable, and it was easy to produce common casting defects such as shrinkage, shrinkage, pores, inclusions, and cracks.
Casting Guide Vane
The Three Gorges Hydro Turbine Unit is the world’s largest installed power generating unit. The large castings and forgings of the 26 hydroelectric units on the left bank, right bank and underground are almost all dependent on imports. Domestic products with intellectual property rights have reached the international leading level.
There are three common processing methods for guide vanes: sand casting, electroslag casting and Casting Guide Vane.
Compared with conventional sand casting and forging guide vanes, electroslag fusion casting guide vanes solidify in accordance with sequential crystallization, which eliminates the inherent solidification defects of ordinary casting, especially for parts with strict requirements for flaw detection, and its overall performance is high. Moreover, due to the dual effects of electroslag refining and electric force, the base parts of the produced parts are uniform in structure and the inclusions are dispersed, so they have good anti-cavitation and abrasion resistance. And fatigue performance has also been improved.
The above is a detailed introduction of the turbine guide vanes, I hope to help everyone.