Water bucket of impulse turbine

Abstract

The water bucket comprises a water bucket body, one end of the water bucket body is an installation end used for being connected with a water turbine hub, and the water bucket is characterized in that a plurality of fish scale imitation bodies in a protruding fish scale shape are distributed on the inner surface of the water facing side of the water bucket body in an overlapped mode, and the whole upper surface of each fish scale imitation body is in an arched arc shape; one end of the fish scale imitation body forms a head part with higher thickness, the other end of the fish scale imitation body is gradually reduced in thickness and extends to form a tail part, the fish scale imitation body is bilaterally symmetrically arranged in the width direction, and the whole head part is of a fillet structure in the horizontal direction; the fish scale imitation bodies are arranged in rows, and the head parts of the fish scale imitation bodies on the rear side cover and are overlapped on the tail parts of the fish scale imitation bodies on the front side, so that the fish scale imitation bodies are sequentially and continuously overlapped to form a structure which is integrally distributed on the inner surface of the upstream side of the water bucket body. According to the method, the abrasion resistance of the water bucket of the impact water turbine under the silt-laden condition can be better improved, the adaptability of the water bucket to the multi-grading and complex silt condition is improved, and the service life of the water bucket is prolonged.

Description

Technical Field

[0001] This invention relates to the field of water turbine power generation equipment technology, specifically to an impulse water turbine bucket. Background Technology

[0002] An impulse turbine is a type of hydroelectric generator that converts water energy into mechanical energy by using a special guide vane mechanism to draw a free jet of kinetic energy towards the runner buckets. This jet causes the runner to rotate and perform work. Impulse turbines are suitable for high-head power stations. They convert water from a pressurized pipe into a high-speed jet through nozzles, which then impinges on the runner, driving it to rotate and thus rotating the generator rotor to generate electricity.

[0003] The conventional turbine bucket structure includes a long, concave, arc-shaped bucket body. One end of the bucket body is the mounting end for connection to the turbine hub. Some buckets have a semi-circular notch-shaped jet outlet at the outer end, and a water-dividing blade is installed along the length of the bucket at the center of the inner wall of the water-facing side to better improve the stress conditions. However, the bucket must withstand the impact of high-intensity water flow for a long time during operation. Under harsh conditions of high head (≥800m~1000m) and high sand content (mixed particles of various sizes), the water-facing side of the bucket is subjected to strong erosion and repeated skidding by high-speed sand-laden jets, which can easily lead to failure. Common failure modes of the bucket include: localized erosion on the water-facing side of the inlet bucket, especially near the water-dividing blade; grooving and coating peeling along the flow direction; edge lifting leading to secondary erosion and causing more severe wear on the outlet edge of the bucket until it is completely worn away (broken, chipped), etc.

[0004] To better improve the defects and enhance the water bucket's resistance to silt impact, the commonly used traditional methods mainly involve resisting silt erosion through integral hard materials, spray coatings, honeycomb / micro-pits, etc. These methods have the following disadvantages and limitations: (1) It is difficult to change the incident angle of silt particles, and the normal erosion of silt particles still accounts for the vast majority and dominates. It is difficult to better alleviate the impact of water flow and silt overall. (2) Due to the lack of sand guide and discharge design, the sand discharge and sand guide capacity of the water bucket blades on the water-facing surface under jet impact is insufficient, especially the secondary impact caused by high-grade sand particles (large particles, high strength) in the key areas of the water bucket under stress. (3) The current welding method of water bucket-hub makes it impossible to quickly, extensively or locally repair silt damage, resulting in high downtime costs. CN202511442036.X once disclosed a method for determining the distribution parameters of an impact turbine, a water bucket, and pins. In this patented solution, multiple pins are embedded along the normal direction on the back surface of the water bucket, which can improve the overall strength of the water bucket, but it still cannot solve the problem of the water bucket's front surface being eroded by silt.

[0005] CN202511442024.7 previously disclosed an impulse turbine, an anti-abrasion bucket, and a method for setting up an anti-abrasion structure. This method uses a dot-matrix distributed convex and concave point structure on the inner surface of the bucket. Under strong impact water flow, a water film forms within the concave points. This water film generates tension, thus buffering the impact of sediment and protecting the inner surface of the bucket, effectively improving the anti-abrasion performance of the bucket during long-term operation under high sediment content conditions. However, the concave points distributed around the convex points in this design reduce the connection and support strength between the convex points, preventing them from forming a combined force to resist the impact of the water flow. Each convex point, individually subjected to the strong impact of the water flow, will wear and break down more quickly. It cannot effectively guide the impact of the water flow and the scouring of multi-stage sediment, resulting in poor overall impact resistance, a short service life, and difficulty in maintenance and repair after damage.

[0006] Therefore, how to improve the water bucket to better enhance its resistance to water flow impact and silt erosion is a direction that those skilled in the art have always needed to consider for improvement and research. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is: how to provide an impact turbine water bucket that can better improve the water bucket's resistance to water flow and its resistance to scouring of sediment, so as to improve its structural strength and extend its service life.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] An impact turbine water bucket includes a water bucket body that is generally concave and arc-shaped, with one end serving as an installation end for connection to the turbine hub. The water bucket body is characterized by having a plurality of raised, fish-scale-like protrusions stacked and distributed on its inner surface facing the water. The upper surface of each protrusion is an arched arc, with one end forming a thicker head and the other end gradually decreasing in thickness to form a tail. The protrusions are symmetrically arranged in the width direction, and their heads have rounded corners in the horizontal direction. The protrusions are arranged in rows, with the heads of the rear protrusions overlapping and covering the tails of the front protrusions, thus forming a continuous stacked structure on the inner surface of the water bucket body facing the water.

[0010] With the inner side of the water bucket covered by overlapping fish-scale-like structures, when water flows into the bucket, it impacts these structures. The heads of the fish-scale-like structures are more bulging and receive greater impact force. Their unique shape, with a high head and low tail, guides a large portion of the impact force from the head towards the tail. Because the fish-scale-like structures are stacked sequentially, this force is transmitted layer by layer backward, distributing the impact force across the entire inner surface of the water bucket, where it is ultimately absorbed and absorbed by the overall deformation of the bucket. This decomposition and transfer of impact force better prevents rapid erosion and damage to areas of the bucket subjected to significant localized impact. Furthermore, because the heads of the fish-scale-like structures are nearly elliptical and relatively thick, they form thick, sweeping side edges on both sides, allowing adjacent heads to interlock and create sand-removing grooves. Therefore, the effective impact angle of the incident sediment particles can be reduced, causing them to fall into the discharge channel. Simultaneously, the water flow dispersed by the scouring of the protruding fish-scale-like structures on both sides will collide with each other in the discharge channel, achieving energy dissipation and reducing the impact on the channel itself. With the sediment impact reduced after falling into the discharge channel, it can be better guided and discharged laterally along the channel. Thus, in this design, the biomimetic fish-scale structure achieves the effect of downstream covering and migration, transforming the normal impact of the sediment-laden jet into a low-angle slippage, and better guiding the particles away from the area of ​​highest energy concentration. This significantly improves the overall impact resistance of the water bucket and extends its service life.

[0011] Furthermore, the adjacent rows of fish scale phantoms are staggered along the direction of arrangement, so that the front fish scale phantom has one fish scale phantom attached to the left and right sides above the tail, and the front end of the rear fish scale phantom is attached to the two front fish scale phantoms at the position where they are touching.

[0012] In this way, when the impact on the head of the front fish-scale phantom is transmitted backward, it can spread to both sides, better dispersing the impact. This allows each fish-scale phantom to precisely cover the entire inner surface of the water bucket body on the water-facing side, forming a unified whole and improving the overall impact resistance. At the same time, this staggered arrangement ensures that the outer edges of adjacent staggered fish-scale phantoms are aligned to the greatest extent possible on a diagonal straight line, better forming sand-removing channels radiating outward along the direction of water flow impact. This can accommodate and guide sediment outward, further improving the sand removal effect.

[0013] Furthermore, the tail of the fish-scale phantom is positioned towards the mounting end. This arched structure at the head of the phantom better guides the impact force of the water flow into a force directed towards the mounting end of the water bucket. This force is opposite to the direction of the water flow's outward scouring of the water bucket, thus partially offsetting the outward scouring force of the water flow. The remaining unoffset force is also offset by the turbine hub at the mounting end, further greatly improving the stability and service life of the water bucket.

[0014] Furthermore, a water-dividing blade is provided in the middle of the inner surface of the water-facing side of the water hopper body, and the fish-scale-like tails on both sides of the water-dividing blade are tilted towards the direction of the angle between the water-dividing blade and the mounting end while moving backward.

[0015] In this way, the fish scale-like prototype can convert part of the impact force into a direction toward the installation end, which is then offset by the turbine hub at the installation end. The other part of the impact force is converted into a direction toward the water-dividing blade, where they collide and cancel each other out on both sides at the water-dividing blade, forcibly converting the impact energy into internal energy and dissipating it, thus better improving stability.

[0016] Furthermore, the outer end of the water bucket body is provided with arc-shaped jet notches on both sides of the water-dividing blade. This can better guide the water flow to converge here and then rush out radially along the water bucket turntable, thereby improving the flow pattern of the jet during water bucket rotation, increasing water bucket stability, and extending water bucket life.

[0017] Furthermore, the water-facing side of the water bucket body is provided with a hard and wear-resistant outer layer, a tough and buffering intermediate layer and a supporting base layer from the outside to the inside. The hard and wear-resistant outer layer is formed on the outer surface of the fish scale phantom body, and the tough and buffering intermediate layer is formed inside the fish scale phantom body. The back side of the fish scale phantom body and the water bucket body are made of the same material as the water bucket body and are fixed together to form a supporting base layer.

[0018] This improves the bonding strength between the fish scale-like body and the water bucket, and also enhances the water bucket's resistance to erosion. In specific implementation, the hard, wear-resistant outer layer preferably uses... Or PVD multilayer The thickness ranges from 10µm to 600µm, with a tough buffer in the middle (Ni-Al, Cu based, 0.1mm to 0.3mm). The base material is high-strength stainless steel / forged steel or metal, and carbon fiber can be added to the base metal material to further improve the strength.

[0019] Furthermore, after the fish scale prototype is processed and produced separately, it is positioned by using a tenon and groove joint on the water-facing side surface of the water bucket body at the tail, and then secured by hidden studs or rivets, and finally welded together at the overlapping edge to form a whole.

[0020] This modular structure facilitates the production and processing of the fish-scale phantom, as well as replacement and repair after impact and wear. Furthermore, the lower surface of the fish-scale phantom is horizontally positioned. When the phantom is secured with concealed studs or rivets, its lower surface is compressed and deformed, fitting snugly against the water tank body and the upper surface of the rear half of the front fish-scale phantom. This allows the fish-scale phantom to generate a pre-tightening force through its own installation deformation, better counteracting the erosion force of the water flow during operation and significantly improving its erosion resistance. Alternatively, in practice, the fish-scale phantom can also be directly manufactured on the inner surface of the water tank body on the water-facing side using mold shaping, metal surface etching, or abrasive processing.

[0021] Furthermore, the shape of the fish scale phantom meets the following limiting requirements: the geometric parameters of a single piece of the fish scale phantom are determined by a parameter set. Description; where:

[0022] Length ; width of the piece ;thickness ;

[0023] The overlap allowance o (the length of the area of ​​the fish scale phantom head that is not pressed down) meets the requirements. ;

[0024] Install the angle of attack (the angle between the normal line at the contact point between the fish scale phantom and the water bucket body and the connecting line between the front and rear ends of the fish scale phantom). ;

[0025] Swept-back edge angle (the angle between the centerline along the length of the fish-scale phantom and the equipotential lines with equal velocity potential on both sides of the head). ;

[0026] One-sided arching ratio Leading edge fillet radius .

[0027] The above parameter range was obtained based on experience and geometric calculations combined with simulation model experiments, which can ensure the performance requirements while facilitating production implementation.

[0028] Furthermore, the fish scale-like prototyping is arranged such that the dimensions of the water-facing side surface of the water bucket body gradually decrease from the outer side away from the installation end towards the inner side.

[0029] This is because when the turbine is working, a ring of nozzles around the outer perimeter of the bucket ejects a jet of water that impacts the bucket, driving the runner to rotate and generate electricity. The impact jet enters the bucket at a perpendicular angle to its normal direction, centered on the water-dividing blade. As the bucket rotates with the turbine, the impact jet flows from the turbine hub to the outer edge of the bucket. Therefore, the outer end of the bucket is the area most affected by the impact of water flow and sediment. Simultaneously, because the nozzles are arranged circumferentially around the runner, the centrifugal force causes larger sediment particles to concentrate more on the outer edge. Therefore, the size of the fish-scale phantom gradually decreases from the outside in, allowing the outer fish-scale phantom to better resist the impact and erosion of water flow and sediment, thus improving the strength of the bucket.

[0030] Furthermore, the geometric dimensions of the fish-scale phantom decrease gradually from the outside to the inside on the water-facing side surface of the bucket body in a specific proportion. The reduction proportion is determined by the Stokes number, a parameter of sediment particle kinetics, to define the fractal hierarchy. This forms an overlapping and covering structure on the water-facing surface of the bucket that gradually increases from the inside to the outside of the turbine hub, in order to adapt to sediment conditions with various gradation parameters.

[0031] This design allows sediment particles of different gradations to undergo corresponding changes in impact force and directional migration under the fractal-layered fish-scale shield structure and cover. Specifically, along the inflow and outflow directions of the impacting water flow, the normal impact of high-grade coarse sand is transformed into a low-angle sweeping impact, medium-diameter sediment is laterally migrated to the discharge channel, and small-particle fine sand is guided by the flow to suppress the number of "re-injections" (repeated bouncing). Therefore, this design better enhances the water bucket's resistance to impacts from water flows containing multi-graded and complex sediment conditions, improves its adaptability to impact jets under complex sediment conditions, and increases the structural strength of the water bucket against sediment abrasion.

[0032] In summary, the present invention can better improve the water bucket's resistance to water flow impact and its resistance to erosion by sediment, thereby increasing the structural strength of the water bucket and extending its service life. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the water bucket of the impulse turbine in Embodiment 1 of the present invention.

[0034] Figure 2 This is a schematic diagram illustrating the working principle of the water bucket and the corresponding impulse turbine of the present invention.

[0035] Figure 3 for Figure 1 The diagram shows the arrangement of the fish scale phantoms in each horizontal row, with arrows indicating the direction of water flow.

[0036] Figure 4 for Figure 1The diagram shows the longitudinal overlapping method of the fish scale phantom.

[0037] Figure 5 for Figure 1 The diagram shows a frontal planar view of the fish scale phantom's overlapping method.

[0038] Figure 6 This is a schematic diagram illustrating the steps of configuring scale feature size parameters hierarchically using fractal geometry after the fish scale phantom size is set to three levels in Example 2. Detailed Implementation

[0039] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0040] Example 1: See Figure 1-5 As shown, an impact turbine bucket includes a bucket body 1 that is generally concave and arc-shaped, serving as an elongated spoon. One end of the bucket body is a mounting end 2 for connecting to the turbine hub. The bucket body 1 is characterized by having several raised, fish-scale-like protrusions 3 (see...) distributed on its inner surface on the water-facing side. Figure 1 The upper surface of the fish scale phantom 3 is generally arched, with one end forming a thicker head and the other end gradually decreasing in thickness to form a tail (see...). Figure 4 The fish scale phantom 3 is symmetrically arranged in the width direction, and the head has a rounded corner structure in the horizontal direction (see...). Figure 5 The fish scale phantoms are arranged in three rows, with the head of the rear fish scale phantom overlapping and covering the tail of the front fish scale phantom (see...). Figure 3 This allows the fish scale phantoms 3 to be continuously stacked to form a structure that is distributed as a whole on the inner surface of the water-facing side of the water bucket body.

[0041] After the inside of the water tank is covered with overlapping fish scale-like structures, when the water flows into the inside of the water tank during operation, it impacts the fish scale-like structures (see...). Figure 2The fish-scale phantom head has a higher bulge, resulting in greater impact resistance. Its unique shape, with a high head and low tail, redirects a significant portion of the impact force towards the tail. Because the phantoms are stacked sequentially, this force is transmitted layer by layer backward, distributing the impact force across the entire surface of the bucket's internal cavity, where it is ultimately absorbed and absorbed by the overall deformation of the bucket. This decomposition and transfer of impact force effectively prevents rapid erosion and damage to areas of the bucket subjected to significant localized impact. Furthermore, the near-elliptical and thick head of the phantom creates thick, sweeping side edges on both sides, allowing adjacent phantom heads to interlock and form sand-removing grooves. Therefore, the effective impact angle of the incident sediment particles can be reduced, causing them to fall into the discharge channel. Simultaneously, the water flow dispersed by the scouring of the protruding fish-scale-like structures on both sides will collide with each other in the discharge channel, achieving energy dissipation and reducing the impact on the channel itself. With the sediment impact reduced after falling into the discharge channel, it can be better guided and discharged laterally along the channel. Thus, in this design, the biomimetic fish-scale structure achieves the effect of downstream covering and migration, transforming the normal impact of the sediment-laden jet into a low-angle slippage, and better guiding the particles away from the area of ​​highest energy concentration. This significantly improves the overall impact resistance of the water bucket and extends its service life.

[0042] Among them, the two adjacent rows of fish scale phantoms 3 are staggered along the direction of arrangement, so that the fish scale phantoms on the front side overlap with one fish scale phantom on each side above the tail, and the front end of the head of the fish scale phantoms on the rear side overlaps with the two fish scale phantoms on the sides of the front side.

[0043] In this way, when the impact on the head of the front fish-scale phantom is transmitted backward, it can spread to both sides, better dispersing the impact. This allows each fish-scale phantom to precisely cover the entire inner surface of the water bucket body on the water-facing side, forming a unified whole and improving the overall impact resistance. At the same time, this staggered arrangement ensures that the outer edges of adjacent staggered fish-scale phantoms are aligned to the greatest extent possible on a diagonal straight line, better forming sand-removing channels radiating outward along the direction of water flow impact. This can accommodate and guide sediment outward, further improving the sand removal effect.

[0044] The tail of the fish-scale phantom 3 faces the mounting end 2. This arched head structure of the phantom allows it to better guide the water flow's impact force into a force directed towards the mounting end of the water bucket. This force is opposite to the direction of the water flow's outward scouring of the water bucket, thus partially offsetting the outward scouring force. The remaining unoffset force is also offset by the turbine hub at the mounting end, further significantly improving the water bucket's stability and service life.

[0045] Among them, a water-dividing blade 4 is provided in the middle of the inner surface of the water-facing side of the water hopper body. The tails of the fish scale phantoms 3 on both sides of the water-dividing blade 4 are tilted towards the direction of the angle between the water-dividing blade 4 and the mounting end 2 while moving backward.

[0046] In this way, the fish scale-like prototype can convert part of the impact force into a direction toward the installation end, which is then offset by the turbine hub at the installation end. The other part of the impact force is converted into a direction toward the water-dividing blade, where they collide and cancel each other out on both sides at the water-dividing blade, forcibly converting the impact energy into internal energy and dissipating it, thus better improving stability.

[0047] The outer end of the water bucket body is provided with arc-shaped jet notches 5 on both sides of the water-dividing blade. This can better guide the water flow to converge here and then rush out radially along the water bucket turntable, thereby improving the flow pattern of the jet during water bucket rotation, increasing water bucket stability, and extending water bucket life.

[0048] The water bucket body 1 has a hard wear-resistant outer layer, a tough buffer middle layer and a support base layer arranged sequentially from the outside to the inside on the water-facing side. The hard wear-resistant outer layer is formed on the outer surface of the fish scale phantom body, and the tough buffer middle layer is formed inside the fish scale phantom body. The back side of the fish scale phantom body and the water bucket body are made of the same material and are fixed together to form the support base layer.

[0049] This improves the bonding strength between the fish scale-like body and the water bucket, and also enhances the water bucket's resistance to erosion. In specific implementation, the hard, wear-resistant outer layer preferably uses... Or PVD multilayer The thickness ranges from 10µm to 600µm, with a tough buffer in the middle (Ni-Al, Cu based, 0.1mm to 0.3mm). The base material is high-strength stainless steel / forged steel or metal, and carbon fiber can be added to the base metal material to further improve the strength.

[0050] The fish scale phantom 3 is manufactured separately and positioned by a tenon and groove joint on the water-facing side surface of the water bucket body at the tail. It is then secured by a hidden stud or rivet (not shown in the figure) and welded together at the overlapping edge.

[0051] This modular structure facilitates the production and processing of the fish-scale phantom, as well as replacement and repair after impact and wear. Furthermore, the lower surface of the fish-scale phantom is horizontally positioned. When the phantom is secured with concealed studs or rivets, its lower surface is compressed and deformed, fitting snugly against the water tank body and the upper surface of the rear half of the front fish-scale phantom. This allows the fish-scale phantom to generate a pre-tightening force through its own installation deformation, better counteracting the erosion force of the water flow during operation and significantly improving its erosion resistance. Alternatively, in practice, the fish-scale phantom can also be directly manufactured on the inner surface of the water tank body on the water-facing side using mold shaping, metal surface etching, or abrasive processing.

[0052] The shape of the fish scale phantom meets the following requirements: the geometric parameters of a single piece of the fish scale phantom are determined by a parameter set. Description (see) Figure 4 and Figure 5 );in:

[0053] Length ; width of the piece ;thickness ;

[0054] The overlap allowance o (the length of the area of ​​the fish scale phantom head that is not pressed down) meets the requirements. ;

[0055] Install the angle of attack (the angle between the normal line at the contact point between the fish scale phantom and the water bucket body and the connecting line between the front and rear ends of the fish scale phantom). ;

[0056] Swept-back edge angle (the angle between the centerline along the length of the fish-scale phantom and the equipotential lines with equal velocity potential on both sides of the head). ;

[0057] One-sided arching ratio Leading edge fillet radius .

[0058] The above parameter range was obtained based on experience and geometric calculations combined with simulation model experiments, which can ensure the performance requirements while facilitating production implementation.

[0059] The fish scale-like body is arranged such that its dimensions gradually decrease from the outer side away from the installation end to the inner side on the water-facing side surface of the water bucket body.

[0060] This is because when the turbine is working, a ring of nozzles 6 around the outer perimeter of the bucket ejects a jet that impacts the bucket, driving the runner to rotate and generate electricity. The impact jet enters the bucket at a perpendicular angle to the bucket's normal direction, centered on the water-dividing blade. As the bucket rotates with the turbine, the impact jet flows from the turbine hub to the outer side of the bucket. Therefore, the outer end of the bucket is the area most affected by the impact of water flow and sediment (see...). Figure 2 Meanwhile, since the nozzles are arranged circumferentially on the outer ring of the rotor, when the water flows out, the larger particles of mud and sand will concentrate more on the outer side due to centrifugal force. Therefore, the size of the fish scale prototype decreases gradually from the outside to the inside, which allows the outer fish scale prototype to better resist the impact and scouring of water flow and mud and sand, and to better improve the strength of the water bucket.

[0061] In specific implementation, the fish scale prototype is sized in three levels on the water-facing side surface of the water bucket body, from the outer side away from the installation end towards the inner side. This includes large-scale scales on the outer side, medium-scale scales in the middle, and small-scale scales on the inner side (see [reference]). Figure 1 To more clearly show the three-level structure, dashed lines are drawn between the three areas to indicate the hierarchical division. In reality, there are only changes in size between the areas, and no distance between them.

[0062] Example 2: In this example, based on meeting all the limiting requirements of Example 1, the geometric dimensions of the fish scale phantom in the three-level fish scale phantom are determined according to the fractal level of the sediment particle follow-up parameter (Stokes number) along the inlet and outlet directions of the impact water flow. This forms an overlapping and covering structure with progressively increasing water bucket front surface from the inside to the outside of the turbine hub, in order to adapt to sediment conditions with various gradation parameters. That is, the normal impact of high-grade coarse sand is transformed into low-angle sweeping impact, and medium-sized sediment is laterally migrated to the sediment discharge channel. Small fine sand particles are allowed to pass through the flow and the number of "re-injection" (repeated bouncing) is suppressed.

[0063] This design allows sediment particles of different gradations to undergo corresponding changes in impact force and directional migration under the fractal-layered fish-scale shield structure and cover. Specifically, along the inflow and outflow directions of the impacting water flow, the normal impact of high-grade coarse sand is transformed into a low-angle sweeping impact, medium-diameter sediment is laterally migrated to the discharge channel, and small-particle fine sand is guided by the flow to suppress the number of "re-injections" (repeated bouncing). Therefore, this design better enhances the water bucket's resistance to impacts from water flows containing multi-graded and complex sediment conditions, improves its adaptability to impact jets under complex sediment conditions, and increases the structural strength of the water bucket against sediment abrasion.

[0064] Specifically, in this embodiment, the scale size parameters of each level of the fish scale prototype are configured in detail (see [link to documentation]). Figure 6 This includes the following steps:

[0065] (1) Determine the characteristic dimensions of the fish scale phantom based on the fractal geometric stratification of sediment gradation;

[0066] First, let the scales be at the scale fractal level. Self-similar:

[0067]

[0068] in These are respectively the length / width / thickness of the film; Thickness scaling index (usually) ).

[0069] Based on the coverage rate following a power law, the total area is guaranteed to be distributed across all layers:

[0070]

[0071] Equivalent surface roughness power, approximated using fractal surface:

[0072]

[0073] in For fractals, It is the Hurst exponent. In engineering, it is taken as...

[0074] (2) Calculate the effective impact angle and lateral migration (for each layer k);

[0075] Local effective impact angle:

[0076]

[0077] in This is the local angle of incidence without scales. For installation of angle of attack; To avoid numerical oddities, a lower limit is set (3°-5° is used in engineering).

[0078] The swept edge causes the particles to laterally move within the length of the plate:

[0079]

[0080]

[0081] make , This is the "enhancement coefficient".

[0082]

[0083] (3) Perform sediment gradation (particle) and scale characteristic size matching;

[0084] Size matching based on particle mobility:

[0085]

[0086] The selection rule for "particle size scale" is given: For particle size d, select... .

[0087] k=0, 0<St<0.1, low inertia, viscosity-dominated, small scale structure;

[0088] k=1, 0.1≤St<1.0, particles can slide, medium-sized scaly structure;

[0089] k=2, 0.1≤St<10, particles can slide, large scale structure;

[0090] With k=3 and St≥10, the particles have strong inertia and require a deep fractal structure with strong wear resistance.

[0091] In this example, k=2, divided into three levels: 0, 1, and 2.

[0092] (4) Calculation of fractal coverage;

[0093] Calculate fractal coverage %

[0094]

[0095] r: Hierarchical scaling ratio (0.4~0.6); D: Fractal dimension (D=3-Hurst, in this example=2.2~2.8)

[0096] (5) Calculation of hydraulic loss constraints;

[0097] The hydraulic losses caused by the shape friction of the fractal-level fish-scale phantom conform to the following relationship, which can be approximated by the fractal coverage ratio, where the equivalent roughness of multi-dimensional roughness is taken as the maximum value:

[0098]

[0099] The thickness is near the wall layer; engineering constraints often take... .

[0100] Thus, by employing the above method, the characteristic size parameters of the scales can be configured through fractal geometry based on the sediment gradation and the impact characteristics of the jet on the water-facing surface of the bucket. The configured large-scale scales are better suited to transform the normal impact of coarse sand with a large gradation into a low-angle sweeping jet; the configured medium-scale scales, used to form sand transport channels between the scales, are better able to laterally migrate medium-sized particles to the sand discharge channels; and the configured small-scale scales are better able to guide fine sand with a small gradation into the formed small textured grooves, suppressing its "re-intrusion" frequency. In this way, the characteristic size parameters of the graded and weighted scales can form a coverage rate of different fractal latitudes determined by fractal geometry on the entire water-facing surface of the bucket, reducing abrasion and minimizing hydraulic losses caused by the scale array to within a constraint (<0.3%).

[0101] The specific invention mechanism and calculation formulas involved in the above configuration process are disclosed as follows.

[0102] 1. Jet Flow and Velocity Calibration

[0103]

[0104] example: (This example uses a water head of 800 meters.) v is the velocity of the impact jet, in m / s; H is the water head, in m.

[0105] 2 Effective impact angle reduction (based on surface) )

[0106]

[0107] in This is the local angle of incidence without scales. For installation of angle of attack; To avoid numerically singular lower bounds (recommended) ).

[0108] 3. Erosion Rate Estimation

[0109]

[0110] in This is a conversion factor for volume fraction or mass concentration. Particle density, Characteristic particle size, Based on the actual values ​​used in the project, K is the material-sand type constant.

[0111] The rate of decrease in wear rate is R:

[0112]

[0113] 4. Particle mobility and sand guiding feasibility (Stokes number)

[0114]

[0115] (Under the conditions of high water head coarse sand and sediment gradation) the motion is dominated by ballistic motion, and the particles can slide on the water-facing surface of the bucket, requiring geometric guidance.

[0116] 5 Lateral migration conditions of the swept side edge

[0117] Geometric lateral displacement Δy of the particle within the length Ls:

[0118]

[0119] To ensure that it is introduced into adjacent trenches (with a spacing of approximately Ws), take

[0120]

[0121] 6. Upper limit of hydraulic loss (approximate equivalent roughness)

[0122]

[0123] in Engineering limitations (Converted from unit efficiency).

[0124] To further verify the effectiveness of optimizing the dimensional parameters of the three-level fish scale phantom using fractal geometry in Example 2, the applicant conducted a comparative verification using actual calculation examples.

[0125] The experimental conditions for comparison and verification are as follows:

[0126] Water Head jet .

[0127] Size and probability of mud and sand particles under multi-gradation conditions: probability .

[0128] Local angle of incidence where no scales were added (CFD baseline).

[0129] Allowable efficiency loss: .

[0130] Comparative scheme A simulated the experiment using the method described in Example 1, where the size of the fish scale phantom was not specified. Specifically, a water bucket with a uniform single-scale fish scale phantom was used (all other conditions were as required in Example 1). The specific parameters were as follows:

[0131] .

[0132] Depend on : ; (Abrasion decreased by 59%).

[0133] The number of particle re-injection times remains essentially unchanged. .

[0134] Overall wear (Baseline = 1).

[0135] Comparison scheme B adopts implementation 2, that is, after the fish scale phantom size is divided into three levels, the size of each level is calculated using fractal geometry, wherein:

[0136] Pick .

[0137] layer

[0138]

[0139]

[0140] Through comparative analysis, the effects of Option B can be summarized as follows:

[0141] 1. Impact angle change: When the impact angle of mud and sand is reduced to 10° to 15°, the abrasion intensity typically decreases by 15% to 30% compared to a 30° baseline.

[0142] 2. Selective sand guiding: The fish scale array determined by the fractal geometry method forms similar but different textured sand-guiding grooves or textures, which can better ensure that coarse sand particles are laterally moved into the grooves, and reduce the re-intrusion of fine sand in the high-energy zone (multiple bounces).

[0143] 3. Efficiency controllable: Additional hydraulic losses due to fish scale shape under the constraint of equation (8) .

[0144] 4. Facilitates processing, manufacturing, and installation: Fractal geometry determines multi-layer gradients, enabling the scales to possess both the required wear resistance (hardness) and good ductility, adapting to deformation and expansion under various operating conditions.

Claims

1. A water bucket for an impulse turbine, comprising a water bucket body that is integrally concave and arc-shaped, with one end serving as a mounting end for connection to the turbine hub, characterized in that, Several raised fish-scale-like phantoms are stacked and distributed on the inner surface of the water-facing side of the water bucket body. The upper surface of each fish-scale phantom is an arched arc, with one end forming a thick head and the other end gradually decreasing in thickness to form a tail. The fish-scale phantoms are symmetrically arranged in the width direction, and the heads are rounded in the horizontal direction. The fish-scale phantoms are arranged in rows, with the heads of the rear fish-scale phantoms overlapping and covering the tails of the front fish-scale phantoms, so that the fish-scale phantoms are continuously stacked to form a structure that is distributed on the inner surface of the water-facing side of the water bucket body.

2. The impulse turbine bucket according to claim 1, characterized in that, The adjacent rows of fish scale phantoms are staggered along the direction of arrangement, so that the front fish scale phantom has one fish scale phantom attached to the left and right sides above the tail, and the front of the rear fish scale phantom is attached to the two front fish scale phantoms at the position where they are touching.

3. The impulse turbine bucket according to claim 1, characterized in that, The tail of the fish scale replica is oriented towards the mounting end.

4. The impulse turbine bucket according to claim 1, characterized in that, A water-dividing blade is provided in the middle of the inner surface of the water-facing side of the water bucket body. The fish scale-like tails on both sides of the water-dividing blade are tilted towards the direction of the angle between the water-dividing blade and the mounting end while moving backward.

5. The impulse turbine bucket according to claim 1, characterized in that, The outer end of the water bucket body is also provided with arc-shaped jet notches on both sides of the water-dividing blade.

6. The impulse turbine bucket according to claim 1, characterized in that, The water bucket body has a hard and wear-resistant outer layer, a tough and buffering middle layer, and a supporting base layer arranged sequentially from the outside to the inside on the water-facing side. The hard and wear-resistant outer layer is formed on the outer surface of the fish scale phantom body, and the tough and buffering middle layer is formed inside the fish scale phantom body. The back side of the fish scale phantom body and the water bucket body are made of the same material and are fixed together to form a supporting base layer.

7. The impulse turbine bucket according to claim 1, characterized in that, After the fish scale prototyping body is processed and produced separately, it is positioned by using a tenon and groove joint on the water-facing side surface of the water bucket body at the tail, and then locked by hidden studs or rivets, and finally welded together at the overlapping edge to form a whole.

8. The impulse turbine bucket according to claim 1, characterized in that, The shape of the fish scale phantom meets the following requirements, and the geometric parameters of a single piece of the fish scale phantom are specified by a parameter set. Description; where: Length ; width of the piece ;thickness ; The overlap allowance o (the length of the area of ​​the fish scale phantom head that is not pressed down) meets the requirements. ; Install the angle of attack (the angle between the normal line at the contact point between the fish scale phantom and the water bucket body and the connecting line between the front and rear ends of the fish scale phantom). ; Swept-back edge angle (the angle between the centerline along the length of the fish-scale phantom and the equipotential lines with equal velocity potential on both sides of the head). ; One-sided arching ratio Leading edge fillet radius .

9. The impulse turbine bucket according to claim 1, characterized in that, The fish scale-like prototyping is arranged on the water-facing side surface of the water bucket body, with its dimensions decreasing progressively from the outer side away from the installation end towards the inner side.

10. The impulse turbine bucket according to claim 9, characterized in that, The geometric dimensions of the fish scale phantom decrease gradually from the outside to the inside on the water-facing side surface of the water bucket body according to a specific ratio. The reduction ratio is determined by the Stokes number, a parameter related to the motion of sediment particles, which determines the fractal level.

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