Leakage prevention methods for mixed-flow turbines

Abstract

A leak-proof method for a mixed-flow turbine includes the following steps: a. The turbine runner blades are mounted on the upper crown, and a turbine bottom ring is mounted below the runner blades. A turbine base is fitted over the turbine bottom ring, and a leak-proof device is installed between the turbine bottom ring and the turbine base; b. An upward-facing baffle plate is mounted on the top of the turbine bottom ring. The baffle plate is funnel-shaped, and a downward-facing blocking plate is mounted on the top of the turbine base. The blocking plate consists of two funnel-shaped blocking rings, one upper and one lower. The two funnel-shaped blocking rings have the same small diameter, and the portions with the same small diameter are fixedly integrated. The large openings of the two funnel-shaped blocking rings face opposite directions, thus forming an annular groove on the back surface of the blocking plate. The upward-facing outer edge of the baffle ring engages with the downward-facing annular groove of the blocking plate. This invention significantly prevents water from flowing between the turbine bottom ring and the base into the lower leak-proof device, achieving a flow-blocking effect.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy engineering technology, specifically relating to a leak-proof method for water turbines, mainly applied to mixed-flow water turbines. Background Technology

[0002] Mixed-flow turbines, also known as Francis turbines, have water flowing radially into the runner from all sides and then flowing out of the runner approximately axially. The runner consists of an upper crown, a lower ring, and blades. A lower leak-proof device is installed between the lower ring and the base of the mixed-flow turbine to reduce volumetric losses. Currently, three common types are used: slotted, labyrinthine, and comb-tooth. The upper leak-proof device is installed in the gap between the upper crown of the runner and the front cover plate (top cover), while the lower leak-proof device is installed in the gap between the lower ring of the runner and the base.

[0003] During normal operation of a mixed-flow turbine, some water flows through the turbine runner inlet. Due to the gap between the turbine base and the turbine bottom ring, and the pressure difference between the upstream and downstream sides, this water flows into the sealing ring through the gap between the bottom ring and the runner, and finally into the downstream of the draft tube. Since this water does not enter the runner to perform work, it causes a volumetric loss. Furthermore, the water flowing through the sealing ring affects the pressure distribution of the water flow at the draft tube inlet, thus forming a draft tube vortex, generating unit vibration, and making the turbine-generator unit unstable. Summary of the Invention

[0004] The purpose of this invention is to provide a leak-proof method for a mixed-flow turbine. By setting an interlocking leak-proof structure on the top of the turbine bottom ring and the turbine base, water is significantly blocked from flowing from between the turbine bottom ring and the base into the lower leak-proof device, thus achieving a flow-blocking effect.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A leak-proofing method for a mixed-flow turbine includes the following steps:

[0007] a. The runner blades of the mixed-flow turbine are mounted on the upper crown, and a turbine bottom ring is mounted below the runner blades. A turbine base is fitted over the turbine bottom ring, and a leak-proof device is installed between the turbine bottom ring and the turbine base.

[0008] b. An upward-facing baffle plate is installed on the top of the turbine bottom ring. The baffle plate is funnel-shaped. A downward-facing water-blocking plate is installed on the top of the turbine base. The water-blocking plate consists of two funnel-shaped water-blocking rings, one upper and one lower. The small openings of the two funnel-shaped water-blocking rings are the same diameter, and the parts with the same small diameter are fixedly integrated. The large openings of the two funnel-shaped water-blocking rings face opposite directions, thus forming an annular groove on the back surface of the water-blocking plate. The outer edge of the upward-facing baffle ring is engaged in the annular groove of the downward-facing water-blocking plate.

[0009] In the above-mentioned leak-proof method for mixed-flow turbines, water-blocking grooves are provided on the water-facing surfaces of the upper and lower water-blocking rings of the water-blocking plate in step b. The water-blocking grooves are inclined, and the spiral direction formed by the inclination is opposite to the rotation direction of the turbine.

[0010] In the above-mentioned leak-proof method for mixed-flow turbines, the water-facing surface of the baffle plate in step b is provided with a water-blocking groove, which is inclined and the spiral direction formed by the inclination is opposite to the rotation direction of the turbine.

[0011] By adopting the above technical solution, the present invention has the following technical effects:

[0012] This invention utilizes interlocking water-blocking plates and baffles on the top of the turbine's bottom ring and base to prevent water from flowing downwards and thus stop leaks. Both the baffle and baffle plates have inclined grooves on their water-facing surfaces. The baffle prevents water from flowing downwards, while the baffle prevents water from flowing upwards, preventing water from flowing down into the leak-stopping device through the gap between them. This leak-stopping method is easy to operate; simply install the baffle and baffle plates on the top of the existing leak-stopping device's bottom ring and base, respectively, forming an interlocking structure to achieve the purpose of blocking water. This invention is easy to install and provides a significant leak-stopping effect. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention.

[0014] Figure 2 for Figure 1 Enlarged structural diagram of part A in the middle.

[0015] Figure 3 yes Figure 1 Top view of the water-blocking plate. Detailed Implementation

[0016] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0017] See Figure 1 , Figure 2 and Figure 3 The diagram is labeled as follows:

[0018] 1 is the turbine bottom ring, 2 is the leak-stopping device, 3 is the turbine bottom, 4 is the upper crown, 5 is the runner blade, 6 is the water baffle plate, 7 is the water baffle plate, and 8 is the water-blocking groove.

[0019] A leak-proofing method for a mixed-flow turbine includes the following steps:

[0020] The runner blades 5 of the mixed-flow turbine are mounted on the upper crown 4. The turbine bottom ring 1 is mounted below the runner blades. The turbine base 3 is fitted outside the turbine bottom ring. A leak-proof device 2 is installed between the turbine bottom ring 1 and the turbine base.

[0021] b. An upward-facing baffle plate 7 is installed on the top of the turbine bottom ring. The baffle plate is funnel-shaped. A downward-facing water-blocking plate 6 is installed on the top of the turbine base. The water-blocking plate consists of two funnel-shaped water-blocking rings, one upper and one lower. The small openings of the two funnel-shaped water-blocking rings are the same, and the parts with the same small opening are fixedly integrated into one piece. The joint of the parts with the same small opening is smoothly transitioned. The large openings of the two funnel-shaped water-blocking rings are in opposite directions, thus forming an annular groove on the back surface of the water-blocking plate. The outer edge of the upward-facing baffle ring is engaged in the annular groove of the downward-facing water-blocking plate.

[0022] The leak-proof method for the mixed-flow turbine, such as... Figure 3 As shown, in step b, both the upper and lower water-blocking rings of the water-blocking plate are provided with water-blocking grooves 8 on their water-facing surfaces. The water-blocking grooves 8 are inclined, and the spiral direction formed by the inclined direction is opposite to the rotation direction of the water turbine.

[0023] In the method for preventing leakage of the mixed-flow turbine, the water-facing surface of the baffle plate in step b is provided with a water-blocking groove, which is inclined and the spiral direction formed by the inclination is opposite to the rotation direction of the turbine.

[0024] The installation process of this invention is as follows: The turbine runner blades are installed on the upper crown, and the turbine bottom ring is installed below the runner blades. The turbine base is fitted over the turbine bottom ring, and a leak-proof device is installed between the turbine bottom ring and the turbine base. An upward-facing baffle plate is installed on the top of the turbine bottom ring. The baffle plate is funnel-shaped. A downward-facing blocking plate is installed on the top of the turbine base. The blocking plate consists of two funnel-shaped blocking rings, one upper and one lower. The two funnel-shaped blocking rings have the same small diameter, and the parts with the same small diameter are fixedly integrated. The connection between the parts with the same small diameter is smoothly transitioned. The large openings of the two funnel-shaped blocking rings are in opposite directions, thus forming an annular groove on the back surface of the blocking plate. The outer edge of the upward-facing baffle ring engages with the annular groove of the downward-facing blocking plate, thereby forming a mutually interlocking structure between the baffle plate and the blocking plate. The baffle and water blocking plate of the present invention can be processed in the market or outsourced, and can be mass-produced according to different models of mixed-flow turbines, thereby reducing processing costs.

[0025] The working process of this invention is as follows:

[0026] Water flows through the turbine blades towards the tailrace, scouring the blades and causing the turbine to rotate, thus outputting mechanical energy. After passing through the turbine blades, the water flows into the gap between the baffle plate and the turbine blades, where it is blocked by the baffle plate and enters the turbine blades. From there, it flows towards the tailrace. During this process, the interlocking structure of the baffle plate and the baffle plate perfectly prevents water from flowing into the leak-proof device through the gap between the turbine bottom ring 1 and the turbine base. Simultaneously, the baffle plate has inclined grooves in the opposite direction of the turbine's rotation. The continuous rotation of the turbine blades creates a centrifugal force on the water flowing into the grooves. Under this centrifugal force, the water flows upwards along the inclined grooves and merges back into the water flow at the turbine blades, reducing water loss. A small portion of the water flows onto the lower, funnel-shaped water-blocking ring of the baffle plate. Since the opening of this ring gradually widens downwards, the velocity and centrifugal force of this water flow gradually decrease under the influence of the ring. Under its own gravity, some of this water falls onto the impeller blades below the baffle plate. The water flowing into the impeller blades then flows into the tailrace pipe from both sides of the impeller blades. A small portion of the water flowing onto the baffle plate is blocked by the baffle plate and flows towards the impeller blades, flowing into the tailrace pipe from both sides of the impeller blades. This invention, by setting an interlocking leak-proof structure at the top of the turbine bottom ring and the turbine base, significantly prevents water from flowing between the turbine bottom ring and the base into the lower leak-proof device, achieving a flow-blocking effect.

[0027] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several changes and improvements without departing from the overall concept of the present invention. These changes should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A method for preventing leakage in a mixed-flow turbine, characterized in that, Includes the following steps: The runner blades (5) of the mixed-flow turbine are set on the upper crown (4), the turbine bottom ring (1) is set at the lower part of the runner blades, the turbine base (3) is sleeved on the outside of the turbine bottom ring, and a leak-proof device (2) is installed between the turbine bottom ring (1) and the turbine base. An upward-turning baffle plate (7) is installed on the top of the bottom ring of the turbine. The baffle plate is in the shape of a horn. A downward-turning water-blocking plate (6) is installed on the top of the turbine base. The water-blocking plate is composed of two horn-shaped water-blocking rings, one is the upper water-blocking ring and the other is the lower water-blocking ring. The small opening diameters of the two horn-shaped water-blocking rings are the same, and the parts with the same small opening diameter are fixedly combined into one. The large openings of the two horn-shaped water-blocking rings are in opposite directions, so that an annular groove is formed on the back surface of the water-blocking plate. The upward-turning outer edge of the baffle ring is fastened in the annular groove of the downward-turning water-blocking plate. Water-blocking grooves (8) are provided on the water-facing surfaces of the upper and lower water-blocking rings of the water-blocking plate. The water-blocking grooves (8) are inclined, and the spiral direction formed by the inclined direction is opposite to the rotation direction of the water turbine. The water-facing surface of the baffle plate is provided with a water-blocking groove, which is inclined, and the spiral direction formed by the inclination is opposite to the rotation direction of the water turbine.

Images