A Francis turbine with draft tube and rectification plate

Abstract

The invention discloses a mixed-flow water turbine with an exhaust water pipe provided with current plates. An overflowing area of the mixed-flow water turbine comprises a worm shell (1), a guide blade area (2), a rotary wheel (4) and the exhaust water pipe (7) with the four to six current plates (8), wherein the worm shell (1), the guide blade area (2), the rotary wheel (4) and the exhaust waterpipe (7) are sequentially connected; the diffusion angle beta 1 of the straight cone section of the exhaust water pipe (7) is 6 degrees; the current plates (8) with circular arc sides and the trapezoidal sections are arranged in the exhaust water pipe, and all the current plates (8) are circumferentially arranged around the axis of the water turbine in the mode of being internally attached to theinner wall of the exhaust water pipe (7); the conical angle beta 2, close to the shaft end, of the current plates (8) is 9 degrees; and the angle beta 3 in the thickness control direction of the current plates (8) is 10 degrees. The mixed-flow water turbine aims to increase the energy recovery coefficient of the exhaust water pipe and improve or eliminate the eddy current phenomenon in the exhaustwater pipe under the non-design working condition while improving an unsteady flow field of the rotary wheel to improve the operating performance of the water turbine, and the thought is universal, especially for various forms of water pumps, water turbines and reversible water pump and water turbine units with the exhaust water pipes.

Description

technical field [0001] The invention belongs to the technical field of hydraulic machinery, in particular to a mixed-flow water turbine with a draft tube and a rectifying plate. Background technique [0002] As a renewable energy source, hydropower has less impact on the environment. In addition to providing cheap electricity, it also has the advantages of controlling flooding, providing irrigation water, and improving river navigation. The Francis turbine is the current standard and representative model for the research, design, and manufacture of turbines in hydropower systems. While developing towards high efficiency and large capacity, it also affects the reliability, stability, and safety of the entire machine. put forward higher requirements. [0003] Chinese patent application 201210209725.2 discloses a turbine draft tube vortex generator, which is used to generate a series of small vortices to neutralize the vortex of the hydraulic turbine draft tube itself. The st...

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Problems solved by technology

[0003] Chinese patent application 201210209725.2 discloses a turbine draft tube vortex generator, which is used to generate a series of small vortices to neutralize the vortex of the hydraulic turbine draft tube itself. The structure is simple and the installation is flexible, but the device requires water flow around to generate The vortex, and the neutralization of the new vortex and the draft tube's own vortex is an extremely complicated process, which will cause secondary effect losses

Chinese patent application 201410243350.0 discloses a draft tube for water turbines. In the channel of the draft tube, rectifiers with openings at both ends are provided to suppress the generation and influence of eccentric vortex bands. However, most research results show that the draft tube vortex The belt first appears near the outlet of the runner. The position of the device can only affect the vortex at the end of the vortex belt, and the device needs to be connected to the wall of the draft tube by a fixed rod. On the one hand, the addition of additional components increases the complexity of the structure, and on the other hand On the one hand, the connecting rod located in the flow field will also affect the internal flow of the draft tube. For the second connection method, the connecting rod is fixed on the ground, which increases the sealing work between the internal flow and the outside world.

Chinese patent application 201611243124.8 discloses a double-runner water turbine for cooling towers with spherical helical blades. The helical blades are set in the draft tube to increase the output as the runners rotate at the same speed, but its structure is complex and difficult to process. The cost is high, the performance requirements of the extra rotor shaft and other external structural components are improved, and the additional outlet pipe increases the space required by the unit, and the direction of the runner blade's outflow velocity hits the spiral blade, causing the loss of the flow section to increase, and the entire Increased instability of the internal flow field, etc.

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