Pelton turbine and runner thereof

Abstract

The application relates to the technical field of hydroelectric power generation, in particular to an impulse water turbine and a runner thereof, which comprises a hub and water buckets uniformly distributed on the hub, the water bucket comprises a water bucket blade and a tenon arranged at the root of the water bucket blade, a tenon groove is arranged on the outer periphery of the hub, and the tenon is movably assembled into the tenon groove in a manner with a matching gap; the water bucket blade comprises a water-facing surface layer and a backwater surface layer, the water-facing surface layer is made of a metal material, the backwater surface layer is made of a carbon fiber composite material, and the water-facing surface layer and the backwater surface layer are connected to form a double-bowl-shaped water bucket blade structure symmetrical along a water distribution edge. The high wear resistance of the metal material is combined with the carbon fiber composite material to form a water bucket blade with higher strength and higher anti-abrasion performance. The tenon is arranged at the root of the water bucket blade to realize movable assembly with the hub. Thus, the original rigid connection is changed into flexible movable connection. The water bucket of the runner effectively avoids the problems of wear and broken bucket faced by the existing water bucket.

Description

Technical Field

[0001] This application relates to the field of hydropower technology, specifically to an impulse turbine and its runner. Background Technology

[0002] Impulse turbines are key machines for converting water resources into energy, especially at heads above 700 meters. As hydropower development moves towards higher heads and larger capacities, the hydraulic loads and operating conditions borne by turbine runners and their buckets are becoming increasingly demanding.

[0003] Currently, impulse turbine buckets are generally made of high-strength stainless steel through integral forging or casting. In rivers with high sediment content, especially those containing hard sediment, the high-speed jet carrying sediment particles causes severe impact and erosion on the bucket's upstream surface, easily leading to wear, deformation, or even failure of the cup-shaped curved surface. Simultaneously, to increase single-unit capacity, the runner diameter and bucket size are continuously increasing, with correspondingly higher rotational speeds. This means that the buckets bear not only extremely strong impact loads but also enormous centrifugal loads during operation. Under these extreme combined load conditions, traditional single-metal buckets face severe challenges: their excessive mass leads to a geometric increase in centrifugal stress, restricting further expansion of the runner size; their insufficient rigidity margin easily causes excessive deformation or high-frequency vibration of the bucket, affecting not only the accuracy of the flow channel profile and hydraulic efficiency but also posing a risk of fatigue cracking and even bucket breakage. Existing technologies that simply increase metal thickness to improve rigidity and erosion resistance are approaching the limits of material performance and will viciously exacerbate the centrifugal load problem.

[0004] Furthermore, the runner head of large-capacity, high-speed impulse turbines is generally rigidly connected to the hub by welding. Because the runner of an impulse turbine bears the force of a high-speed jet, long-term operation under the powerful impact of the water flow easily leads to fatigue at the welded joint between the runner head and the hub. Especially since the impulse runner rotates at high speed in the air, and with a certain number of nozzles evenly distributed along the circumference, the load on the runner is discontinuous and intermittent. This accelerates fatigue at the runner-hull connection, causing the welded impulse runner head to easily fracture from the root after prolonged operation. This is a current challenge and limitation faced by high-head, large-capacity impulse turbines, significantly affecting their operational reliability and even limiting their selection for larger capacity and higher head applications.

[0005] Therefore, the existing turbines suffer from bucket breakage and bucket wear, which are not only difficult to avoid but also have a significantly shortened cycle, making it difficult to meet the requirements for long-term safe and reliable operation. Summary of the Invention

[0006] In view of this, the present application provides an impulse turbine and its runner to solve the problems of bucket wear and bucket breakage in existing turbines.

[0007] A first aspect of this application provides a runner for an impulse turbine, including a hub and water buckets evenly distributed on the hub. Each water bucket includes water bucket blades and tenons disposed at the root of the water bucket blades. A tenon groove is provided on the outer circumference of the hub, and the tenons are movably assembled in the tenon groove with a fitting clearance.

[0008] The water bucket blade includes a water-facing surface layer and a water-returning surface layer. The water-facing surface layer is made of metal material, and the water-returning surface layer is made of carbon fiber composite material. The water-facing surface layer and the water-returning surface layer are connected to form a double-bowl-shaped water bucket blade structure symmetrical along the water-dividing edge.

[0009] In one embodiment, the surface on which the tenon mates with the mortise is a toothed surface. The tenon, along the rotation direction of the wheel after assembly, has a first toothed surface on the water-facing side and a second toothed surface on the water-repellent side. The first toothed surface and the second toothed surface have different tooth profile parameters. The upper surface of the tooth of the first toothed surface has a first inclination angle, and the upper surface of the tooth of the second toothed surface has a second inclination angle. The first inclination angle is greater than the second inclination angle, and the tooth depth of the first toothed surface is greater than the tooth depth of the second toothed surface.

[0010] In one embodiment, the tenon has a first toothed sidewall adapted to the shape of a first toothed surface of the tenon, and a second toothed sidewall adapted to the shape of a second toothed surface of the tenon. A first toothed mating gap is formed between the first toothed surface and the first toothed sidewall, and a second toothed mating gap is formed between the second toothed surface and the second toothed sidewall. The toothed depth of the first toothed mating gap is greater than the toothed depth of the second toothed mating gap.

[0011] In one embodiment, the lower end of the tenon is provided with a centrifugal sand discharge chute;

[0012] The centrifugal sand discharge chute is configured to use the centrifugal force generated when the wheel rotates to throw out mud and sand that may enter the gap between the tenon and the mortise.

[0013] In one embodiment, the backwater surface layer is laid with carbon fibers of different lengths and directions in different areas of the water bucket blades. The carbon fibers of different lengths include at least short carbon fibers with a length between several millimeters and 1 centimeter, and long carbon fibers with a length greater than 1 centimeter.

[0014] In the region corresponding to the water-facing surface layer in the direction of the jet flow, long carbon fibers woven in the direction of the jet flow are laid.

[0015] In the oblique jet region corresponding to the water-facing surface layer, short carbon fibers woven along the oblique force direction are laid on the back water surface layer.

[0016] The backwater surface layer is covered with short carbon fibers woven circumferentially along the water bucket blades in the outlet centrifugal region and the root region of the water bucket blades, corresponding to the frontwater surface layer.

[0017] The region along the jet direction of the water-facing surface layer is the central region of the bowl-shaped concave surface on both sides of the water-dividing blade of the water bucket; the oblique jet region of the water-facing surface layer is the outer edge region of the bowl-shaped concave surface of the water bucket and the inner edge region adjacent to the water-dividing blade; the oblique force direction is the force direction when the water-facing surface layer of the water bucket blade is obliquely intersecting the jet; the outlet centrifugal region of the water-facing surface layer is the region where the jet flows out of the water bucket blade under the action of centrifugal force.

[0018] In one embodiment, the water-dividing blade of the water bucket blade is integrally formed from carbon fiber composite material onto the back water surface layer. The back water surface layer has edge grooves extending inward on both sides, and the water-dividing blade has water-dividing blade grooves on both sides. The front water surface layer is snapped and fixed between the edge grooves and the water-dividing blade grooves.

[0019] In one embodiment, the water-facing surface layer and the backwater surface layer are connected by an anchoring bolt. The anchoring bolt passes through the backwater surface layer and is connected to the water-facing surface layer. The head of the anchoring bolt is equipped with a curved washer that fits the curved surface of the backwater surface layer. The anchoring bolt is located in the backwater groove of the water-dividing blade and / or the thick wall of the water bucket blade.

[0020] A second aspect of the present application provides an impulse turbine, including a runner, a distribution coil, and a nozzle connected to the distribution coil as described in the first aspect of the present application.

[0021] The inner wall of the nozzle is provided with helical rifling.

[0022] The spiral rifling is used to rotate the high-speed water flow passing through the nozzle, thereby separating the sediment in the water flow through centrifugal force.

[0023] In one embodiment, the helical rifling is a progressive rifling, and the pitch of the helical rifling gradually decreases along the direction of water flow;

[0024] The helical rifling includes alternating positive and negative rifling, which extend in a helical shape along the axial direction of the nozzle;

[0025] The nozzle has spiral ridges on its inner wall, which form the male line, and the inner wall surfaces between adjacent spiral ridges form the female line; or

[0026] The nozzle has a spiral groove on its inner wall, which forms the negative line, and the inner wall surface between adjacent spiral grooves forms the positive line.

[0027] In one embodiment, a partitioned additive layer is provided on the working surface of the water bucket of the impeller, and the position of the partitioned additive layer corresponds to the mud and sand impact area on the outer edge of the jet after being treated by the helical rifling.

[0028] The first aspect of this application provides an impulse turbine runner, comprising a hub and buckets evenly distributed on the hub. Each bucket includes bucket blades and tenons disposed at the root of the bucket blades. A tenon groove is provided on the outer circumference of the hub, and the tenons are movably fitted into the tenon groove with a fitting clearance. Each bucket blade includes a water-facing surface layer and a water-returning surface layer. The water-facing surface layer is made of a metal material, and the water-returning surface layer is made of carbon fiber composite material. The water-facing surface layer and the water-returning surface layer are connected to form a double-bowl-shaped bucket blade structure symmetrical along the water-dividing edge. By combining the high wear resistance of the metal material with the high specific strength and high specific stiffness of the carbon fiber composite material, a runner bucket blade with higher strength, higher abrasion resistance, and lighter weight is formed. Under high head and high sediment conditions, bucket deformation, cracking, and even bucket breakage are avoided, thus improving the service life of the buckets. By utilizing the high strength and load-reducing properties of carbon fiber, the first-order natural frequency of the bucket can be significantly increased, and the damping ratio of jet pulsation impact can be improved. This effectively solves the problems of insufficient rigidity and strength of large-sized impeller buckets in high-head, high-speed, and large-size impeller turbines, as well as their susceptibility to wear and failure under conditions of high sediment loads. This not only enables the design and manufacture of impeller turbines with larger outer diameters and higher rigidity, but also makes it possible to manufacture large buckets with larger dimensions, greater thickness, larger outer diameters, and higher reliability. By setting a specifically shaped tenon structure at the root of the bucket blades, a movable assembly with the hub tenon groove is achieved. This structure allows for a movable assembly method with a fitting clearance, enabling the bucket to undergo restricted (non-free) displacement within the gradually changing gap under different jet impact loads, thus transforming the traditional rigid connection into a flexible movable connection. This allows the bucket to reliably connect to the hub without relying on welding or bolt fixing, solving the common problem of easy breakage of head and hub welds under high-intensity water impact forces in the original method.

[0029] It is understandable that the beneficial effects of the second aspect mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1This is a schematic diagram of the runner of an impulse turbine provided in one embodiment of this application;

[0032] Figure 2 This is a schematic diagram of the water bucket structure of an impulse turbine provided in one embodiment of this application;

[0033] Figure 3 This is an assembly diagram of the water bucket and the hub provided in one embodiment of this application;

[0034] Figure 4 This is a schematic diagram of the mortise and tenon connection between the water bucket and the wheel hub provided in another embodiment of this application;

[0035] Figure 5 This is a top view of a turbine runner assembled using a mortise and tenon joint structure according to an embodiment of this application;

[0036] Figure 6 yes Figure 5 Schematic diagram of the inclined setting of the tenon groove;

[0037] Figure 7 yes Figure 5 Enlarged schematic diagram of the centrifugal sand discharge chute in the middle;

[0038] Figure 8 This is a diagram showing the correspondence between the distribution of carbon fibers in different regions of the water-facing layer and the backwater layer, provided in an embodiment of this application.

[0039] Figure 9 This is a schematic diagram of the motion trajectory of the impact jet relative to the water bucket provided in one embodiment of this application;

[0040] Figure 10 This is a schematic diagram of the cross-section of the bucket of an impulse turbine provided in an embodiment of this application;

[0041] Figure 11 This is a schematic diagram showing the connection between the water-facing surface layer and the water-returning surface layer through anchoring and limiting bolts according to an embodiment of this application;

[0042] Figure 12 This is a schematic flowchart of a method for determining the thickness of the water-facing and back-facing layers according to an embodiment of this application;

[0043] Figure 13 This is a schematic diagram of the structure of the impulse turbine provided in the embodiments of this application;

[0044] Figure 14 This is a schematic diagram of the nozzle structure of an impulse turbine provided in an embodiment of this application;

[0045] Figure 15 This is a schematic diagram of the nozzle structure of an impulse turbine provided in another embodiment of this application;

[0046] Figure 16 This is a schematic diagram of the nozzle structure of an impulse turbine provided in another embodiment of this application;

[0047] Figure 17 This is a schematic flowchart of a method for determining helical rifling parameters provided in an embodiment of this application;

[0048] Figure 18 This is a schematic diagram of the partitioned additive layer of an impulse turbine provided in one embodiment of this application;

[0049] Figure 19 This is a schematic diagram of the structure of a water bucket base provided in one embodiment of this application;

[0050] Figure 20 This is a schematic diagram of a water bucket structure integrating a thrust bearing base and tenons provided in an embodiment of this application;

[0051] Figure 21 This is a schematic diagram of a wheel structure formed by connecting the water bucket and hub of the integrated thrust bearing base and tenon according to an embodiment of this application. Detailed Implementation

[0052] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0053] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0054] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0055] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0056] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0057] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0058] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0059] like Figures 1-3 As shown in the embodiment of this application, an impeller for an impulse turbine includes a hub 2 and buckets 1 evenly distributed on the hub 2. The buckets 1 include bucket blades 15 and tenons 14 disposed at the root of the bucket blades 15. The outer circumference of the hub 2 is provided with a tenon groove 21, and the tenon 14 is movably assembled in the tenon groove 21 with a fitting clearance.

[0060] like Figure 2 As shown, the water bucket blade 15 includes a water-facing surface layer 11 and a water-returning surface layer 12. The water-facing surface layer 11 is made of metal material, and the water-returning surface layer 12 is made of carbon fiber composite material. The water-facing surface layer 11 and the water-returning surface layer 12 are connected to form a double-bowl-shaped water bucket blade structure symmetrical along the water-dividing blade 123.

[0061] In applications, the water jet is a key component used to withstand the impact of water flow and convert water flow energy into mechanical energy. It typically consists of jet blades, a jet back, and a water-dividing blade, evenly distributed around the hub. In this embodiment, the water jet blades are double-bowl shaped to accommodate the impact of the water flow and the energy conversion. The water-dividing blade is located at the center of the water jet blades, dividing the jet into two parts, which enter the two halves of the water jet respectively. When high-speed water is ejected from the nozzle and impacts the water-dividing blade of the water jet, the water flow is divided into two parts, which enter the two halves of the water jet respectively. During the flow of water within the water jet, the speed and direction of the water flow change due to the shape and curvature of the water jet, thus generating an impact force on the water jet. This impact force drives the water jet to rotate through the hub, driving the impeller and main shaft to rotate, converting the kinetic energy of the water flow into mechanical energy.

[0062] In application, when high-speed water impacts the water-facing surface of the bucket, the jet impact force is transmitted to the tenon at the root of the bucket blades, causing it to enter the toothed tenon groove and fit tightly against the inner surface of the groove along the direction of the wheel's rotation, thus transferring the impact load to the hub. Depending on the magnitude of the impact load, under different operating conditions (i.e., different water heads), the length of the toothed gap occupied by the tenon varies. That is, the greater the impact load, the deeper the tenon enters the mortise groove, and the larger the proportion of the fit clearance occupied, and vice versa.

[0063] This application embodiment achieves a movable assembly with the hub tenon groove by setting a specifically shaped tenon structure at the root of the water bucket blade. This allows the water bucket to reliably connect to the hub without relying on welding or bolt fixing, fundamentally avoiding the risk of weld fatigue fracture. This structure enables a movable assembly method with a fitting clearance, allowing the water bucket to undergo restricted (non-free) displacement within the gradually changing gap under different jet impact loads, thus transforming the original traditional rigid connection into a flexible movable connection. Due to its self-adaptive, weld-free, boltless, and fixed connection characteristics, the rigid roots of the water head and hub are also eliminated, fundamentally solving the problem of easy fracture of the water head and hub welds under high-intensity water impact forces, a common problem in the original method.

[0064] In one embodiment, such as Figure 4 As shown, the surface of the tenon 14 that mates with the mortise 21 is a toothed surface.

[0065] The tooth profile of this application significantly increases the contact area, enabling impact loads to be uniformly transmitted through multiple tooth surfaces, effectively dispersing stress concentration. At the same time, the tooth meshing effect can also generate a self-locking effect during high-speed rotation, enhancing the stability of the connection.

[0066] In one embodiment, the tenon 14 has a first toothed surface 141 on the water-facing side and a second toothed surface 142 on the back side along the rotation direction of the wheel after assembly, the first toothed surface 141 and the second toothed surface 142 having different tooth profile parameters.

[0067] In application, the tenon teeth are larger on the water-facing side of the hub or bucket and smaller on the water-repellent side. This fit clearance method allows for adjustment of the tenon's occupation of the mortise tooth clearance length under different operating conditions (i.e., different water heads) based on the magnitude of the jet impact load. That is, the greater the jet impact load, the deeper the tenon enters the mortise, and the larger the proportion of the toothed fit clearance.

[0068] This application's embodiments achieve asymmetrical force characteristics by differentiating the tooth profile parameters of the upstream and downstream sides. This allows the upstream side of the water bucket to provide a larger bearing area and interlocking force when subjected to impact loads, while the downstream side maintains appropriate flexibility, thereby optimizing the load distribution.

[0069] In one embodiment, the upper surface of the tooth head of the first tooth surface 141 has a first tilt angle θ1, and the upper surface of the tooth head of the second tooth surface 142 has a second tilt angle θ2, wherein the first tilt angle θ1 is greater than the second tilt angle θ2.

[0070] The tooth depth of the first tooth surface 141 is greater than the tooth depth of the second tooth surface 142.

[0071] In application, the toothed surfaces of the mortise and tenon structure are asymmetrically distributed along the rotation direction of the wheel (θ1 > θ2). The biting force is proportional to the sine of the centrifugal force at an angle θ between the tooth surface and the tangential direction of rotation. The component of the centrifugal force perpendicular to the tooth surface is the biting force, F. 咬合 =F 离心 ×sinθ, the structural coefficient (k=sinθ) is determined by the slope of the toothed gap. When θ1 is 3°~8° (corresponding to k≈0.052~0.139), the tenon and mortise interlocking force generated by centrifugal force is greater than the nozzle jet impact force, which meets the requirements for safe and stable operation.

[0072] The embodiments of this application use a larger water-facing tilt angle to help guide the tenon to wed into the mortise more smoothly under impact load, while the differential tooth depth design ensures that the optimal contact state can be maintained under different load conditions, realizing adaptive matching between load and structural response.

[0073] In one embodiment, the trajectory line of the tooth center of the tooth surface is any one of a circle, an ellipse, or a parabola.

[0074] Circular, elliptical, and parabolic shapes are all curves with good mechanical properties, which can optimize stress transmission paths and reduce local stress concentration. At the same time, these shapes are also easy to manufacture with precision, ensuring fitting accuracy and reliability.

[0075] This application embodiment also provides a mortise and tenon connection structure for the bucket and hub of an impulse turbine, which includes a mating tenon 14 and a mortise 21;

[0076] Tenon 14 is set at the root of water bucket blade 15;

[0077] The tenon 21 is provided on the outer circumference of the hub 2;

[0078] The tenon 14 is movably assembled in the mortise 21 with a fitting clearance.

[0079] The mortise and tenon connection structure of this application embodiment ensures the force balance of the impact impeller, significantly reducing the unbalanced eccentric force of the impeller under high-head impact. With multiple nozzles evenly distributed along the circumference, the water buckets indirectly bear the impact of the nozzle jets. During fixed welding, any unbalanced force generated for various reasons acting on the impeller becomes a harmful eccentric force, which can severely affect the shaft stability of the impact unit. The mortise and tenon connection structure with progressive clearance allows the water buckets evenly distributed along the circumference of the impeller hub to self-adjust the fit clearance of the tenon in the mortise under unbalanced force conditions, thereby offsetting the eccentric force of the shaft and causing the impeller to regain circumferential equilibrium. The mortise and tenon structure has the ability to automatically adjust the fit clearance under high-speed rotation and impact water loads, allowing the tenon and mortise to adapt to the impact load and ensuring a balanced force distribution, avoiding the problem or defect of concentrated weld stress leading to failure and fracture under rigid welding methods. Because of the adoption of a movable assembly mortise and tenon structure with no welding or bolt fixing, the water bucket and its hub can withstand greater and higher impact loads and head conditions in principle, and are easier to assemble and maintain. This greatly improves the hydraulic performance and safety performance of the impulse turbine, and also significantly increases the range of head and single-unit capacity of the impulse turbine.

[0080] In applications, mortise and tenon joints can be made of forged steel, which possesses a certain degree of elasticity. When subjected to high-speed rotation or impact water flow loads, relative movement and stress occur between the tenon and mortise. Due to the elastic deformation of steel, the mortise and tenon joint can automatically adjust the fit clearance within a certain range. For example, under impact loads, the steel undergoes compression or tension deformation, temporarily increasing or decreasing the gap between the tenon and mortise to adapt to load changes. Compared to rigid welding, mortise and tenon joints offer a degree of flexibility, absorbing and buffering impact energy and reducing structural damage. The anisotropic properties of forged steel also play a positive role in stress distribution. Forged steel exhibits different mechanical properties in different directions. Mortise and tenon joint designs typically consider the anisotropic properties of steel, ensuring that the load is transmitted along the direction of higher strength in the forged steel, thereby improving the structure's load-bearing capacity and stress balance, and avoiding the problem of stress concentration and potential failure / fracture in welds.

[0081] Therefore, the above connection method creates a non-rigid force transmission path, which allows for small relative displacement through the fitting gap, thereby absorbing impact energy, avoiding stress concentration, and completely avoiding the material property degradation problem caused by welding.

[0082] In one embodiment, the tenon 21 has a first toothed sidewall that matches the shape of the first toothed surface 141 of the tenon 14, and a second toothed sidewall that matches the shape of the second toothed surface 142 of the tenon 14. There is a first toothed fitting gap between the first toothed surface 141 and the first toothed sidewall, and there is a second toothed fitting gap between the second toothed surface 142 and the second toothed sidewall. The toothed depth d1 of the first toothed fitting gap is greater than the toothed depth d2 of the second toothed fitting gap.

[0083] In application, the shapes of the tenon and mortise are set with a non-toothed fit clearance according to the combination of constant centrifugal force generated by high-speed rotation and intermittent jet impact force in the direction of rotation. This ensures that the tenon clamping force generated by centrifugal force is greater than the safety threshold of instability (vibration, displacement, deformation) of intermittent jet, thus guaranteeing that the impact impeller and water bucket with tenon and mortise connection can operate safely and stably under minimum and maximum working conditions.

[0084] In application, because the tooth depth of the first toothed fit is greater than that of the second toothed fit, an asymmetrical gap is formed between the bucket and the hub in the direction of rotation. The centrifugal force generated by the high-speed rotation of the impeller causes the tenon at the root of the bucket to tightly mesh with the hub along the asymmetrical toothed gap. This meshing force is proportional to the centrifugal force. When the rotation speed is greater than 200 r / min and the outer diameter of the hub is greater than 2 m, the meshing force generated by the centrifugal force is 22.38 tn. This fastening force is sufficient to offset the effect of the wave-like impact force generated by 4 or 6 nozzles. Under the combined action of high-speed jet and centrifugal force, the tenon and mortise of the bucket fit tightly in the direction of rotation, maintaining high stability under various working conditions, generating strong torque, driving the impeller of the impulse turbine to rotate, and without producing in-slot vibration or harmful displacement or deformation.

[0085] The mortise and tenon structure in this embodiment employs a special tooth-like shape, which generates a self-locking effect or adaptive adjustment capability under stress. When subjected to lateral loads, the wedge-shaped portion of the tenon fits tightly with the mortise. As the load increases, the tenon further weaves into the mortise, thereby automatically adjusting the gap and enhancing the stability of the connection. This mortise and tenon structure effectively disperses the load. When subjected to impact loads, the contact surface between the tenon and the mortise is large, allowing the load to be transferred and dispersed through multiple contact surfaces, avoiding the generation of concentrated stress.

[0086] This application's embodiments achieve a progressive load transfer mechanism by limiting the difference in the fit clearance between the mortise sidewall and the tenon tooth surface. This allows the tenon to embed deeper into the mortise when the impact load increases, automatically increasing the effective contact area and thus keeping the stress level within a safe range.

[0087] In one embodiment, such as Figure 5 , 6 As shown, the line connecting the two side walls of the tenon 21 and the direction of water flow, and the line connecting the two toothed surfaces of the tenon 14 and the direction of water flow, all form a certain angle θ3, which is an acute angle.

[0088] In application, the tenon groove on the hub forms a certain angle θ3 with the horizontal center line of the hub according to the direction of water flow from the impeller, and the tenon at the root of the bucket adopts the same inclination angle. The centrifugal force generated by the high-speed rotation of the impact impeller in a fixed direction causes the bucket to generate a clamping force in the tenon groove through the oblique angle θ3 distributed on the hub. This force, together with the biting force generated by the large and small teeth θ1 and θ2 mentioned above, works to ensure the good hydraulic and mechanical performance of the bucket.

[0089] Because the tenon at the base of the water bucket is directly assembled at a certain angle in the direction of rotation into the hub tenon groove with the same inclination angle at the top opening and bottom stop, under operating conditions, the tenon of the water bucket automatically finds and adjusts its position in the tenon groove through the combined action of centrifugal force and water flow impact force, via the aforementioned hub tenon groove distribution inclination angle θ3, the tenon teeth and the inclination angles θ1 and θ2 of the water-facing / backwater-facing surfaces, that is, automatically adjusts the fit clearance.

[0090] The embodiments of this application utilize an angled design to enable the mortise and tenon joint to generate a clamping effect through centrifugal force during rotation. This self-tightening structure ensures that the connection will not loosen under high-speed conditions, while the inclined arrangement also facilitates drainage and sand removal, keeping the interface clean.

[0091] In one embodiment, such as Figure 7 As shown, a centrifugal sand discharge chute 211 is provided at the lower end of the tenon 21;

[0092] The centrifugal sand discharge chute 211 is configured to use the centrifugal force generated when the wheel rotates to throw out the mud and sand that may enter the gap between the tenon 14 and the mortise 21.

[0093] In application, the tenon groove adopts a centrifugal sand discharge chute. By setting a centrifugal chute at the lower end of the tenon groove in the direction of the impeller rotation, the powerful centrifugal force generated by the high-speed rotation of the impact turbine is used to throw the mud and sand in the gap of the tenon structure to the bottom of the impeller along the centrifugal chute. This ensures that the gap fit of the tenon structure is not adversely affected by the high mud and sand operating conditions. At the same time, by reasonably setting the angle of the centrifugal sand discharge chute, it is ensured that the centrifugal sand discharge of the tenon groove will not affect the impeller, thus ensuring the safe operation of the impeller of the tenon-and-mortise connection method.

[0094] The centrifugal sand discharge chute design of this application embodiment cleverly utilizes the centrifugal force generated by the rotation of the impeller. The chute structure can promptly throw out silt particles that have intruded into the mating gaps, preventing jamming or wear caused by silt deposition, and ensuring the long-term reliable operation of the tenon and mortise connection in sandy water flow.

[0095] In application, the metal material of the water-facing layer 11 can be high-strength stainless steel or forged steel, while the carbon fiber composite material of the backwater layer 12 can be an ultra-high-strength carbon fiber layer wound with fibers according to the hydraulic load characteristics of the water-facing impact jet. The thickness distribution of the two layers can be determined by the impact pressure of the jet, which is determined by the head Hw and flow rate Q, and the sediment gradation index, to ensure that the carbon fiber + metal double-layer composite water bucket has both sufficient rigidity and strength, as well as good wear resistance and elastic plasticity, and a jet pulsation impact damping ratio. At the same time, the reasonable matching of the thicknesses δ1 of the carbon fiber layer and δ2 of the high-strength metal layer can improve the impact hydraulic performance of the water bucket and impeller, which is not only highly reliable and wear-resistant, but also prevents resonance and local fatigue fracture, thereby ensuring the hydraulic efficiency and operational safety of the water bucket under ultra-high head and ultra-large capacity conditions.

[0096] This application combines the high wear resistance of metallic materials with the high specific strength and high specific stiffness of carbon fiber composites to form turbine runner blades with higher strength, higher abrasion resistance, and lighter weight. Under high head and high sediment conditions, this avoids bucket deformation, cracking, and even breakage, thus extending the bucket's service life. Utilizing the high strength and load-reducing properties of carbon fiber, the first-order natural frequency of the bucket is significantly increased, and the jet pulsation impact damping ratio is improved. This effectively solves the problems of insufficient rigidity and strength of large impulse turbine runners and buckets under high head, high speed, and large-size conditions, as well as their susceptibility to wear and failure under high sediment conditions. This not only enables the design and manufacture of impulse turbines with larger outer diameters and higher rigidity, but also makes it possible to design and manufacture large buckets with larger dimensions, greater thickness, larger outer diameters, and higher reliability.

[0097] In one embodiment, the backwater surface layer 12 is covered with carbon fibers of different lengths and directions in different areas of the water bucket blades 15.

[0098] In applications, the winding method and direction of carbon fiber are determined based on the jet impact load transfer on the upstream side and the flow impact load distribution on the downstream side. Specifically, the laying direction of the carbon fiber can be determined according to the force direction in different areas of the upstream side of the bucket blades. The length, tensile strength, and tensile modulus of the carbon fiber are determined based on the magnitude of the force in different areas of the upstream side of the bucket.

[0099] In application, the carbon fiber modulus, weaving direction and combination of long and short fibers on the back surface of the water bucket blade can be determined by the following four factors: (1) the hydraulic force characteristics of the jet on the water bucket's front surface, (2) the hydraulic force characteristics and centrifugal force of the flow around the back surface, (3) the lightweight index of the water bucket, and (4) the requirements for the outer diameter and height expansion space under the condition of improved force on the outer edge of the hub.

[0100] This application embodiment achieves precise and customized design of material properties by directionally laying carbon fibers of different lengths and directions in different regions of the water jet blades. This design method can be specifically enhanced according to the differences in the actual jet impact force, centrifugal force, and complex hydrodynamic loads borne by each region, so that the main load-bearing direction of the material matches the main stress direction, thereby optimally utilizing the anisotropic potential of carbon fiber composite materials and maximizing the mechanical efficiency of the structure while reducing weight.

[0101] In one embodiment, the impact force Ft on the water-facing surface, the surface stress σ of the water bucket, and the centrifugal force Fc can be calculated. The length and direction of the limit switch can be determined by the direction and magnitude of the impact force Ft and the centrifugal force Fc.

[0102] In applications, the impact of water on the water-facing surface... ;

[0103] Where Ft represents the impact force of the water on the upstream side. For jet velocity, β is the velocity of the water flow when it leaves the bucket, and β is the deflection angle of the bucket. For traffic, The density is the water flow density.

[0104] In application, the surface stress of the water bucket σ=(Ft / A)≤σ 允许 ;

[0105] Where A is the effective force-bearing area of ​​the water bucket facing the impact.

[0106] In application, centrifugal force Fc = mω 2 r;

[0107] Where m is the mass of the water bucket, ω is the angular velocity of the impeller, and r is the radius of rotation or the pitch circle radius of the impeller.

[0108] In one embodiment, the carbon fibers of different lengths include at least short carbon fibers 121 with a length between several millimeters and 1 centimeter, and long carbon fibers 122 with a length greater than 1 centimeter.

[0109] The tensile strength of short carbon fiber 121 and long carbon fiber 122 is not less than 4000 MPa, and the tensile elastic modulus is not less than 290 GPa.

[0110] This application's embodiments, through the combined application of short and long fibers, ensure that the material can achieve both high macroscopic stiffness and large load transfer through long fibers, while utilizing short fibers to better fill complex curved surfaces and withstand localized complex stresses. The aforementioned tensile strength and elastic modulus guarantee, at the material level, that the water bucket structure can withstand ultra-high water head impact loads and high-speed rotating centrifugal loads, further improving the strength of the water bucket.

[0111] In one embodiment, such as Figure 8 As shown, in the region 111 of the backwater surface layer 12 corresponding to the water-facing surface layer 11 in the direction of the jet flow, long carbon fibers 122 woven in the direction of the water flow are laid.

[0112] Among them, the region 111 in the direction of the jet in the water-facing surface layer 11 is the central region of the bowl-shaped concave surface on both sides of the water-dividing blade 123 of the water bucket blade.

[0113] In application, one end of the water bucket blade is the root for connecting to the hub, and the other end is the top. The water-facing and water-repellent surfaces of the two semi-bowl structures of the water bucket blade are both curved surfaces. The direction from the root to the top and following the curvature of the curved surface is defined as the direction of water flow in this embodiment. The direction perpendicular to the direction of water flow along the curved surface around the water-dividing blade 123 is defined as the circumferential direction. The water flow direction in the central region of the bowl-shaped concave surface is the direction extending from one end of the water bucket blade to the other along the curved surface of the center of the bowl-shaped concave surface.

[0114] This application embodiment greatly enhances the ability of the water bucket to resist impact deformation and fatigue failure by laying long carbon fibers along the water flow direction in the core area where the water bucket is subjected to the most severe impact from the positive jet.

[0115] In one embodiment, the backwater surface layer 12 is covered with short carbon fibers 121 woven along the oblique force direction in the oblique jet region 112 corresponding to the frontwater surface layer 11.

[0116] Among them, the oblique jet region 112 of the water-facing surface layer 11 is the outer edge region of the cup-shaped concave surface of the water bucket blade and the inner edge region adjacent to the water-dividing blade 123, such as Figure 9 As shown, the oblique force direction is the force direction when the water-facing surface layer 11 of the water bucket blade is obliquely intersected with the impact jet 4.

[0117] In application, the force direction of the outer edge region of the cup-shaped concave surface of the water bucket blade and the inner edge region of the adjacent water-dividing blade 123 is consistent with the circumferential direction of the water bucket blade. Here, the short carbon fibers 121 of the oblique jet region 112 can be laid in the circumferential direction to enhance the water bucket's resistance to oblique impact force.

[0118] This application embodiment reinforces the complex stress area where the jet collides obliquely with the water bucket using obliquely laid short fibers or woven fabrics. This effectively withstands the shear stress and multi-directional stress generated by fluid-structure interaction in this area, avoiding the mechanical weaknesses that occur with fibers in a single direction, thereby significantly improving the torsional resistance and overall durability of the water bucket's flank region.

[0119] In one embodiment, the back surface layer 12 is covered with short carbon fibers 121 circumferentially woven along the water bucket 1 in the outlet centrifugal region 113 and the root region 114 of the water bucket blades corresponding to the front surface layer 11.

[0120] The outlet centrifugal region 113 of the water-facing surface layer 11 is the area where the jet flows out of the water bucket blades under the action of centrifugal force.

[0121] In application, short carbon fibers 121 in the outlet centrifugal region 113 and the root region 114 of the bucket blades are woven circumferentially along the bucket blades to improve the bucket's resistance to circumferential stress and prevent it from breaking due to centrifugal force during high-speed rotation. These short fibers have relatively low strength and stiffness but better molding properties, allowing for more uniform distribution within the complex circumferentially shaped matrix of the bucket, filling in complex shapes and corners, achieving uniform coverage and good adhesion.

[0122] This embodiment of the application lays fibers circumferentially at the water bucket outlet and root, two key locations subjected to enormous centrifugal tensile stress, aligning the fiber direction with the main direction of the centrifugal tensile stress. This effectively constrains radial deformation and directly bears circumferential tensile force, effectively preventing structural cracking or excessive deformation of the water bucket due to centrifugal force under high-speed rotation.

[0123] In one embodiment, such as Figure 10 As shown, the water-dividing blade 123 of the water bucket blade is integrally formed from carbon fiber composite material on the back water surface layer 12. The back water surface layer 12 has edge grooves 124 extending inward on both sides. The water-dividing blade 123 has water-dividing blade grooves 125 on both sides. The front water surface layer 11 is snapped and fixed between the edge grooves 124 and the water-dividing blade grooves 125.

[0124] In application, by setting special stops and grooves on the inner sides of the upper and lower water outlet edges of the carbon fiber layer on the back surface of the water bucket, the metal front surface layer is directly assembled and fixed in the water bucket 1 by means of stops and grooves using the elastic prestress of the carbon fiber layer.

[0125] In this embodiment, the water-dividing blade 123 is integrally formed and mates with the edge groove 124 to achieve a secure installation of the metal water-facing surface. The elasticity of carbon fiber material is utilized to achieve a tight connection, resulting in a simple and reliable structure.

[0126] In one embodiment, such as Figure 11As shown, the water-facing surface layer 11 and the back-facing surface layer 12 are connected by an anchoring limit bolt 126. The anchoring limit bolt 126 passes through the back-facing surface layer 12 and is connected to the water-facing surface layer 11. The head of the anchoring limit bolt 126 is equipped with a curved washer 127 that fits the curved surface of the back-facing surface layer 12. The anchoring limit bolt 126 is located in the back-facing groove of the water-dividing blade 123 and / or the thick wall of the water bucket 1.

[0127] In application, the anchoring limit bolt 126 is made of high-strength stainless steel, the same material as the water-facing surface of the bucket, and is connected to the internal thread of the carbon fiber integrated perforated riser. Considering the influence of the protrusions on the back surface of the bucket on the jet and the hydraulic performance of the subsequent bucket, the limit bolt is set at locations such as the groove on the back surface of the water-dividing blade 123 and the upper and lower thick walls, and is symmetrically arranged in the upper and lower buckets. The curved gasket 127 is formed according to the curved surface of the distribution position of the anchoring point on the back of the bucket, that is, it maintains the same curved surface shape as the bucket shape at that location, so as to fit the back surface of the bucket without gaps.

[0128] This embodiment employs anchor bolts with curved gaskets 127 for fastening in specific thick-walled areas. This provides a strong normal preload, ensuring that the metal and composite material layers remain tightly bonded and deform collaboratively under complex loads. Placing the bolts in concealed locations such as the grooves of the water divider 123 minimizes their interference with the flowing water, demonstrating a deep integration of structural design and hydraulic performance requirements.

[0129] In one embodiment, the thicknesses of the upstream surface layer 11 and the downstream surface layer 12 are determined based on the first-order natural frequency of the hydraulic characteristics, the jet pulsation impact damping ratio, the bucket-profile displacement / force transmission rate, the impeller pitch circle radius, and the circumferential thrust at the bucket root.

[0130] In application, the water-facing surface layer 11 can be configured to occupy approximately 1 / 3 of the half-bowl-shaped thickness of the entire water bucket blade, and the water-repellent surface layer 12 can occupy approximately 2 / 3 of the half-bowl-shaped thickness of the entire water bucket blade. This proportion can also be optimized based on the thickness determination method of this application embodiment to achieve higher water bucket strength.

[0131] In applications, such as Figure 12 As shown, the initial thickness of the carbon fiber on the back side is set to δ1, and the thickness of the high-strength steel on the front side is set to δ2. Then, the mass m of the carbon fiber layer is calculated. δ1 The high-strength steel on the water-facing surface has a mass of m. δ2 And calculate the total mass of the water bucket m1=m δ1 +m δ2 The water bucket's lightweight load reduction factor a = m0 - m1 / m0 needs to reach a set value, such as 30%. Then, assuming the water bucket's static stiffness K remains constant, the natural frequency f = (K / m) is calculated. 1 / 2 / 2π. After obtaining the natural frequency f, the first-order natural frequency of the water bucket is further calculated as f1 = f0 / (1-a). 1 / 2 Damping ratio of bucket blades ζ=C / Ce, bucket-hub displacement / force transmission coefficient T d T f Based on Td, Tf can calculate the bucket-profile displacement / force transmissivity, runner pitch circle radius, and bucket root circumferential thrust (i.e., hub circumferential thrust). By setting constraints such as increasing the bucket's first-order natural frequency f1 by a certain percentage (e.g., 20%), achieving a certain bucket blade damping ratio ζ (e.g., 300%), and decreasing the bucket-profile displacement / force transmissivity within a certain range (e.g., 1%-6%), the initial thickness of the carbon fiber on the back surface (δ1) and the thickness of the high-strength steel on the front surface (δ2) are iteratively optimized until a better value is reached. This results in an increase in the runner pitch circle radius and a decrease in the bucket root circumferential thrust.

[0132] Where Z represents the number of nozzles, and Hw represents the head of the impulse turbine. T The circumferential torque generated by the water thrust is given by m0, where m0 is the original weight of the all-metal water bucket, C is the viscous damping coefficient of the system, and Ce is the critical damping.

[0133] This application embodiment correlates the thickness parameters of the upstream surface layer 11 and the downstream surface layer 12 with the first-order natural frequency of the hydraulic characteristics, the jet pulsation impact damping ratio, the water bucket-profile displacement / force transmission rate, the impeller pitch circle radius, and the circumferential thrust at the root of the water bucket. This ensures that the final determined water bucket thickness is not only safe in terms of static strength, but also optimal in terms of dynamic response, thereby fundamentally guaranteeing the water bucket's operating efficiency, stability, and ultra-long service life under extreme working conditions.

[0134] This application also provides an impulse turbine, such as... Figure 13 As shown, it includes the aforementioned impeller, water distribution coil 5, and nozzle 3 connected to the water distribution coil 5;

[0135] like Figure 14 As shown, the inner wall of the nozzle 3 is provided with helical rifling 31;

[0136] The spiral rifling 31 is used to generate rotation in the high-speed water flow passing through the nozzle 3, so as to separate the mud and sand in the water flow through centrifugal force.

[0137] In application, nozzle 3 is located at the end of the water distribution coil 5 of the impulse turbine. The main function of nozzle 3 is to convert the pressure energy of water into kinetic energy, forming a high-speed jet that impacts the turbine runner, causing it to rotate, thereby converting water energy into mechanical energy. Figure 15As shown, nozzle 3 is equipped with a nozzle needle 32. By adjusting the position of the nozzle needle 32, the flow area of ​​nozzle 3 can be changed, thereby controlling the water flow rate and jet velocity. When pressurized water enters the nozzle, due to the contraction of the nozzle, the water velocity gradually increases and the pressure gradually decreases. Through the action of the helical rifling 31, the jet flows out from the nozzle orifice 33 of nozzle 3 with a rotating water flow characteristic. The pressure energy of the water is converted into kinetic energy, forming a high-speed impact jet 4 acting on the water-facing surface 11 of water tank 1 (water tank 1 includes a water-facing surface 11 and a back surface 12). The impact jet 4 impacts the water tank blades on the impeller, causing the impeller to rotate, which in turn drives the generator to generate electricity.

[0138] In one embodiment, such as Figure 16 As shown, the spiral rifling 31 includes alternating male and female riflings 311 and 312, which extend spirally along the axial direction of the nozzle 3.

[0139] In application, each helical rifling 31 consists of a male groove (width a / mm) and a female groove (width b / mm), and has a specific depth h (mm) and pitch P (length of one revolution of a water particle / m). When the male groove is formed by the inner wall of the nozzle, the depth h is the concave depth of the female groove. When the female groove is formed by the inner wall of the nozzle, the depth h is the convex height of the male groove.

[0140] The embodiments of this application feature a spiral channel composed of alternating positive and negative lines. The positive lines provide the main guiding surface and directly interact with the water flow to transfer momentum, while the negative lines accommodate secondary flow of the fluid and stabilize the flow field. This alternating structure ensures that the water flow obtains a uniform and continuous tangential velocity component, avoiding the generation of unstable vortices or separation zones, thereby forming a stable and symmetrical rotating flow field. This is a key structural guarantee for achieving efficient and uniform centrifugal separation.

[0141] In one embodiment, the inner wall of the nozzle 3 is provided with spiral ridges, the spiral ridges forming a positive line 311, and the inner wall surface between adjacent spiral ridges forming a negative line 312; or

[0142] The inner wall of nozzle 3 is provided with spiral grooves, which form negative lines 312, and the inner wall surface between adjacent spiral grooves forms positive lines 311.

[0143] This application's embodiments cover two different manufacturing process paths: additive manufacturing and subtractive manufacturing. The first method, which forms a positive line by constructing convex ridges, is more suitable for welding or additive manufacturing. The second method, which forms a negative line by cutting grooves, is suitable for traditional machining. Both methods can achieve the same function of guiding water flow rotation. The specific method can be adapted to different production conditions and technical backgrounds, reducing the threshold and cost of process implementation and enhancing the practicality and promotional value of this invention.

[0144] In one embodiment, the width of the positive line 311 is less than or equal to the width of the negative line 312.

[0145] This embodiment of the application, by designing the width of the male line to be less than or equal to that of the female line, can minimize the flow resistance of the spiral protrusions to the main body while ensuring sufficient contact area to transmit rotational torque. The narrower male line reduces abrupt changes in the flow cross-section and streamline interference, while the wider female line channel provides smoother flow space for the fluid, helping to maintain a higher axial flow velocity and reduce turbulence intensity and hydraulic losses, thereby optimizing the overall flow efficiency of the nozzle while achieving sediment separation.

[0146] In one embodiment, the helical rifling 31 is a gradually decreasing rifling, and the pitch of the helical rifling 31 gradually decreases along the direction of water flow.

[0147] In applications, pitch P refers to the axial distance between corresponding points of two adjacent threads on the helix.

[0148] In this embodiment, the helical rifling is specifically designed as a gradually decreasing pitch rifling, meaning the pitch gradually decreases along the flow direction. This achieves precise control over the water flow's rotational acceleration process. The larger pitch at the inlet section makes the initial rotation of the water flow relatively gentle, which is conducive to the stable development of the flow and avoids a sudden drop in pressure. Subsequently, the pitch gradually decreases, which is equivalent to gradually increasing the rotational curvature of the guide surface, thereby continuously increasing the rotational angular velocity of the water flow and steadily enhancing the centrifugal force. This allows sediment particles to undergo a gradually accelerated migration process, avoiding particle collision rebound or flow field instability that may be caused by a sudden increase in centrifugal force, thus improving the reliability and efficiency of the separation process.

[0149] In one embodiment, the spiral rifling 31 has the same rotation direction as the turbine.

[0150] This embodiment avoids interference between the rotating jet and the turbine's motion, conforming to the system's dynamic coordination. When the direction of the rotating jet is the same as the direction of the water bucket's motion, the relative velocity when the water impacts the water bucket can be reduced, thereby reducing hydrodynamic noise and vibration caused by the impact. It also facilitates the smooth entry of the jet into the water bucket and efficient energy transfer, improving the stability and energy conversion efficiency of the turbine operation, and optimizing the overall performance at the system level.

[0151] In one embodiment, the number of helical rifling grooves 31 is an integer multiple of 12.

[0152] In this embodiment, the number of rifling grooves is specifically limited to an integer multiple of 12, ensuring that the grooves are completely symmetrical and uniformly distributed around the nozzle circumference. This high degree of circumferential symmetry ensures that the guiding force on the water flow is uniform and consistent, thereby generating a stable, symmetrical, and rigid vortex with no central axis drift. This effectively prevents localized wear and vibration caused by flow field asymmetry, providing a stable and predictable sediment distribution pattern for the water bucket.

[0153] In one embodiment, such as Figure 17 As shown, the parameters of the helical rifling 31 are determined by the following method:

[0154] Based on the physical principles of particle motion in a rotating flow field, the flow field characteristics required to migrate sediment particles to the outer edge of the jet are determined.

[0155] Establish a model relating the geometric parameters of the helical rifling 31 to the flow field characteristics;

[0156] The parameters of the helical rifling 31 are determined based on the relational model, including the pitch, the width of the male rifling 311, the width of the female rifling 312, and the depth of the helical rifling 31.

[0157] In the application, input sediment gradation parameters (including particle size d) p and density ρ p The equivalent radius r of the nozzle inner wall and the length L of the nozzle helical rifling segment are first determined based on the radial migration distance Δr and the fluid axial velocity U. x The radial slip velocity w required to calculate sediment particles r req Its value is approximately equal to (Δr·U) x ) / L; then, using this radial slip velocity, combined with the fluid viscosity μ, the density difference between the particles and the fluid (ρ) p Parameters such as -ρ) are used to derive the minimum tangential velocity u through mechanical equilibrium relationships. θmin (d p ),Right now The ratio of minimum tangential velocity to axial velocity is then defined as the minimum rotational intensity S. min (d p ), that is, S min (d p )=u θmin / U x Furthermore, a critical condition for sediment separation is proposed, requiring the actual rotational intensity S to be greater than S0. min (d p ), where S is derived from the empirical formula Calculate, k s The correction coefficient is used; when the separation condition is met, the pitch P corresponding to the target separation gradation must satisfy the constraint inequality. Finally, based on the known nozzle inner diameter D, helical section length L, and the calculated S... min (d p The key design parameters of the rifling are determined by reverse engineering, including pitch P, bore width a, groove width b, and rifling depth h.

[0158] This application starts with the goal of sediment separation (migrating to the outer edge), reverse-engineers the required flow field characteristics (such as minimum tangential velocity), and then solves for specific structural dimensions by establishing a physical model between the rifling geometry parameters and the flow field characteristics. This ensures that the designed rifling parameters meet functional requirements while also considering operational efficiency and reliability, greatly improving the success rate and optimization level of the design.

[0159] In one embodiment, such as Figure 18 As shown, a partitioned additive layer 118 is provided on the working surface of the water bucket 1. The position of the partitioned additive layer 118 corresponds to the mud and sand impact area on the outer edge of the jet after being treated by the spiral rifling 31.

[0160] In applications, the partitioned additive layer 118 can be a wear-resistant coating. The wear-resistant coating in the outer region withstands the impact of mud and sand, while the central region forms a protective area that only withstands the impact of clean water. The thickness and range of the additive need to be determined based on the distribution of mud and sand and the impact energy.

[0161] The nozzle 3 is mounted on the water distribution coil 5, which is a ring-shaped high-pressure water pipe extending from the pressure steel pipe of the impulse turbine to the centerline elevation of the impulse turbine runner. Four or six nozzles are evenly distributed from the coil 5, providing powerful water pressure that, after passing through the nozzles (with internal nozzle adjustment), forms an impact jet 4, driving the water buckets to rotate the turbine hub at high speed. The turbine hub 2 and the water buckets 1 mounted on it together form the runner of the impulse turbine, which is driven to rotate by the impact jet 4.

[0162] In application, the hub 2 is an intermediate component connecting the water buckets of an impulse turbine runner and the main shaft, serving to transmit torque and support the water buckets. It has a disc-shaped or hub-shaped structure with a certain thickness and diameter to meet strength and rigidity requirements. It has a central hole for mounting with the main shaft and is fixed to the water buckets along its circumference by welding or bolting. The hub needs to withstand the enormous impact force and torque transmitted from the water buckets and is generally forged from high-strength alloy steel. Its working principle is as follows: high-speed water flow impacts the water buckets of the turbine, generating a rotational torque in the buckets due to the force of the water flow. This torque is transmitted to the main shaft through the hub, thereby driving the generator rotor to rotate and converting water energy into electrical energy.

[0163] This application proposes an adaptive design for the water bucket based on the characteristics of the jet after helical rifling, namely, the setting of a zoned additive layer. This achieves targeted protection, eliminating the need for uniform reinforcement of the entire working surface of the water bucket. Instead, high-hardness wear-resistant material is applied to the outer edge track based on the concentrated impact area of ​​sediment determined by the rotating jet. This functionally driven gradient material design can significantly improve the protection level and lifespan of critical wear-resistant areas while minimizing the use of expensive wear-resistant materials and controlling manufacturing costs.

[0164] In one embodiment, a space may also be provided between the water jet blade 15 and the tenon 14 as follows: Figure 19 The thrust bearing base 16 shown is configured to be connected to the hub 2 via an assembly structure;

[0165] The thrust bearing substrate 16 includes a first layer 161 and a second layer 162 stacked together along the circumference of the rotor. The first layer 161 is disposed at the non-driving end of the thrust bearing substrate 16 along the rotation direction of the rotor, and the second layer 162 is disposed at the driving end of the thrust bearing substrate 16 along the rotation direction of the rotor.

[0166] The thrust bearing base 16 is configured such that multiple identical thrust bearing bases 16 can be closely connected end to end along the outer circumferential direction of the hub 2.

[0167] In application, the non-driving end is the backwater side 12 of the water bucket 1, and the driving end is the frontwater side 11 of the water bucket 1. Through the segmented thrust bearing base 16 connected end to end in the circumferential direction, the pulsating impact of the single bucket is converted into circumferential band shear stress, realizing the uniform transmission and diffusion of load from jet hydraulics to water bucket to thrust bearing to hub, significantly reducing the risk of local stress concentration and fatigue at the outer edge of the hub and the root of the water bucket.

[0168] This application's embodiment can transform the impact load concentrated at the root of a single bucket in a traditional welded connection into a banded compressive-shear stress distributed along the outer edge of the hub, borne jointly by multiple thrust bearing substrates tightly connected circumferentially. This force transmission and diffusion mechanism fundamentally reduces stress concentration at the hub edge and significantly improves fatigue resistance. It not only solves the problems of load transmission and hydraulic stability in ultra-high head and ultra-large capacity impulse turbine runners, but also greatly reduces the requirements for the hub's outer diameter by increasing the thickness of the thrust bearings. This allows for a 20%–30% reduction in the hub outer diameter of ultra-high head (e.g., 1000m) and ultra-large capacity (e.g., 875MW to 1000MW) impulse turbines, significantly reducing the difficulty of hub manufacturing. Thus, while achieving a runner structure with higher stability and reliability, it also solves the problem of limiting the size of ultra-large impulse turbine hubs.

[0169] In one embodiment, the circumferential thickness of the first tile layer 161 is greater than the circumferential thickness of the second tile layer 162.

[0170] In application, the thickness distribution of the two layers of the thrust bearing substrate 16 is determined according to the impact pressure of the jet (determined by the head h and flow rate Q) to ensure that the thick and thin tiles on both sides have sufficient rigidity and strength, as well as good wear resistance and elastic shaping performance. At the same time, the reasonable combination of the thickness δ1 of the Babbitt alloy thin tile and the δ2 ​​of the high-strength stainless steel thick tile can enable the water bucket impeller under this method to have good impact hydraulic performance, thereby ensuring the hydraulic efficiency of the water bucket.

[0171] In this embodiment, the circumferential thickness of the first tile layer is greater than that of the second tile layer. This ensures that the first tile layer, as the main load-bearing component, possesses sufficient stiffness and section modulus to efficiently transmit the enormous circumferential thrust, while the relatively thinner second tile layer focuses on utilizing its elastic deformation capacity to absorb impact energy. This combination of thick and thin layers optimizes the overall stiffness-flexibility ratio of the base and is a key structural parameter for achieving the synergistic effect of efficient load-bearing and effective buffering.

[0172] In one embodiment, the first tile layer 161 is made of high-strength steel, including stainless steel or forged steel.

[0173] In this embodiment, the first layer is made of high-strength steel, such as stainless steel or forged steel. The high yield strength and fatigue strength of high-strength steel ensure its structural integrity and dimensional stability under ultra-high thrust loads, while its excellent wear resistance effectively resists the erosion of water containing silt. It is particularly suitable for harsh working conditions where the non-driving end is subjected to compressive stress and fretting wear for a long time, ensuring the long-term durability of the base body.

[0174] In one embodiment, the second tile 162 is made of Babbitt alloy.

[0175] In this embodiment, the thrust bearing base is made of Babbitt alloy with a good elastic coefficient at the driving end (water-facing side of the bucket) and high-strength stainless steel or forged steel at the non-driving end (water-returning side of the bucket). Under the impact of the symmetrically distributed jets along the circumference, the buckets convert the jet impact load into a circumferential water thrust load, which is applied to the thrust bearing. The thrust bearings are connected end-to-end without gaps at the outer edge of the hub. That is, the thrust bearing connected to this bucket is both the bearing bearing of the previous bucket's thrust bearing and the load-bearing bearing of the next thrust bearing. By using the asymmetrical metal material thrust bearings with the above-mentioned gapless assembly structure as the bucket base, the compressive plasticity of the Babbitt alloy bearings can be utilized to absorb the pulsating load generated by the jets and high-speed rotation. The high strength and hardness of the stainless steel / forged steel can be used to transmit the ultra-large thrust load, driving the impact-type impeller to rotate at high speed. High-strength steel (stainless steel / forged steel) thick tiles (i.e., the first layer of tiles) ensure pressure resistance and dimensional stability, while Babbitt alloy thin tiles (i.e., the second layer of tiles) provide surface contact compliance and damping. The circumferential thrust tile has a more reasonable range of contact surface pressure (7.9-9.5MPa) and composite deflection (≈0.03 mm).

[0176] In this embodiment, the second layer is made of Babbitt alloy. Babbitt alloy is soft, tough, and has strong embedding properties. Its low elastic modulus and high damping characteristics enable it to effectively absorb and dissipate the high-frequency pulsating energy from the jet impact through a small amount of plastic deformation, thereby protecting the high-strength steel layer behind it and the hub connection interface, and greatly improving the smoothness of the entire transmission system under variable load.

[0177] In one embodiment, the first tile layer 161 and the second tile layer 162 are combined to form the thrust tile substrate 16 by molding hot melt welding or die casting.

[0178] In this embodiment, the first and second tile layers are composited by molding hot-melt welding or die casting, ensuring a high-strength metallurgical bond or mechanical interlocking interface between the dissimilar materials. This robust composite method prevents peeling or loosening between the two layers under alternating loads, ensuring that thrust loads can be smoothly transferred from the Babbitt alloy layer to the high-strength steel layer. This is a key technological guarantee for achieving collaborative operation of the double-layer structure.

[0179] In one embodiment, the assembled structure is a mortise and tenon joint structure, and a tenon 14 is provided at the root of the thrust bearing base 16 for engaging with the mortise and tenon groove provided on the outer edge of the hub 2.

[0180] The assembled structure in this application embodiment is a mortise and tenon joint. The mortise and tenon joint achieves precise positioning and circumferential constraint of the thrust bearing base on the hub. Its multi-faceted contact characteristics can provide huge shear resistance to transmit torque, while allowing a certain degree of thermal expansion freedom in the radial and axial directions, avoiding the thermal stress generated by rigid connection, and the assembly process is also simpler and more reliable.

[0181] In one embodiment, the thrust bearing base 16 is provided with an interface structure for connecting the water bucket blades 15. The interface structure is configured to be connected to one or more water bucket blades 15 as a whole by welding or integral forging.

[0182] In application, the thrust bearing base 16 serves as the base or pedestal for the water bucket blades 15. The water bucket blades 15 are connected to the thrust bearing base 16 as a whole by welding or integral forging. One or two water bucket blades 15 can be connected to one thrust bearing base 16. The thrust bearing bases 16 are connected end to end without gaps and form a circle. The root of each thrust bearing base 16 is connected to the wheel hub, and in this embodiment, a mortise and tenon joint is used. In addition to the mortise and tenon joint, other assembly methods can also be used, and this embodiment is not limited to them.

[0183] The thrust bearing substrate of this application is provided with an interface structure for connecting the water bucket blades, and supports both welding and integral forging. This provides great flexibility in the manufacturing process. Welding facilitates the replacement and maintenance of the water bucket, while integral forging can achieve the ultimate performance of continuous streamlines and no weak interfaces. The most suitable manufacturing strategy can be selected according to different working conditions and usage concepts.

[0184] In one embodiment, the axial width of the thrust pad of the water bucket base, the circumferential thickness of the first pad layer 161, the circumferential thickness of the second pad layer 162, and the connection depth between the thrust pad and the hub 2 are jointly determined by the water head, the circumferential surface pressure of the thrust pad, the number of water buckets, and the target value of the water bucket deflection.

[0185] The key dimensional parameters of the water turbine base in this application embodiment are determined by the operating conditions such as water head and surface pressure, ensuring that the base of each turbine is not designed based on experience, but is a customized component that has been precisely calculated and optimized, so that its structural strength and elastic buffering performance can be perfectly matched with the specific hydraulic environment and power level, thereby achieving the optimal balance between safety and economy.

[0186] like Figure 20 As shown, in this embodiment of the application, the water bucket blade 15 and the aforementioned water bucket base (including the thrust bearing base 16 and the tenon 14) are integrated into an integral structure of a water bucket 1.

[0187] This application embodiment integrates the water bucket base and water bucket blades into a complete water bucket assembly. This integrated design transforms the water bucket assembly into a standard modular unit that can be independently manufactured, tested, and replaced, greatly improving the maintainability of the water bucket while ensuring that the impact load borne by the water bucket blades can be directly introduced into the composite layer structure of the base through the optimal path.

[0188] like Figure 21As shown, the integrated bucket blades 15 and the bucket bases are connected to the bucket 1 and hub 2 to form a runner. Multiple impulse turbine buckets are assembled to the outer edge of the hub 2 through their bucket bases, and the multiple bucket bases are connected end to end along the circumference of the hub 2. The bucket blades 15 of the bucket 1 include a water-facing surface layer 11 and a water-returning surface layer 12. The water-facing surface layer 11 is made of metal material, and the water-returning surface layer 12 is made of carbon fiber composite material. The water-facing surface layer 11 and the water-returning surface layer 12 are connected to form a double-bowl-shaped bucket blade structure symmetrical along the water-dividing blade 123.

[0189] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A runner for an impulse turbine, characterized in that, Includes a hub (2) and water buckets (1) evenly distributed on the hub (2). The water buckets (1) include water bucket blades (15) and tenons (14) provided at the root of the water bucket blades (15). The outer circumference of the hub (2) is provided with a mortise (21). The tenons (14) are movably assembled in the mortise (21) with a fitting clearance. The water bucket blade (15) includes a water-facing surface layer (11) and a water-returning surface layer (12). The water-facing surface layer (11) is made of metal material, and the water-returning surface layer (12) is made of carbon fiber composite material. The water-facing surface layer (11) and the water-returning surface layer (12) are connected to form a double-bowl-shaped water bucket blade structure symmetrical along the water-dividing blade (123). The backwater surface layer (12) is covered with carbon fibers of different lengths and directions in different areas of the water bucket blade (15). The carbon fibers of different lengths include at least short carbon fibers (121) with a length between several millimeters and 1 centimeter, and long carbon fibers (122) with a length greater than 1 centimeter. The backwater surface layer (12) is covered with long carbon fibers (122) woven in the direction of the jet flow in the region (111) corresponding to the frontwater surface layer (11). The backwater surface layer (12) is covered with short carbon fibers (121) woven along the oblique force direction in the oblique jet region (112) corresponding to the frontwater surface layer (11). The back surface layer (12) is covered with short carbon fibers (121) circumferentially woven along the water bucket blades (15) in the outlet centrifugal region (113) and the root region (114) of the water bucket blades, corresponding to the front surface layer (11). Among them, the region (111) of the water-facing surface layer (11) along the jet direction is the central region of the bowl-shaped concave surface on both sides of the water-dividing blade (123) of the water bucket blade (15); the oblique jet region (112) of the water-facing surface layer (11) is the outer edge region of the bowl-shaped concave surface of the water bucket blade (15) and the inner edge region adjacent to the water-dividing blade (123), and the oblique force direction is the force direction when the water-facing surface layer (11) of the water bucket blade (15) is obliquely intersecting with the jet; the outlet centrifugal region (113) of the water-facing surface layer (11) is the region where the jet flows out of the water bucket blade (15) under the action of centrifugal force.

2. The runner of the impulse turbine as described in claim 1, characterized in that, The surface of the tenon (14) that mates with the mortise (21) is a toothed surface. The tenon (14) has a first toothed surface (141) on the water-facing side and a second toothed surface (142) on the back side along the rotation direction of the wheel after assembly. The first toothed surface (141) and the second toothed surface (142) have different tooth profile parameters. The upper surface of the tooth of the first toothed surface (141) has a first inclination angle, and the upper surface of the tooth of the second toothed surface (142) has a second inclination angle. The first inclination angle is greater than the second inclination angle, and the tooth depth of the first toothed surface (141) is greater than the tooth depth of the second toothed surface (142).

3. The runner of the impulse turbine as described in claim 1, characterized in that, The tenon (21) has a first toothed sidewall that matches the shape of the first toothed surface (141) of the tenon (14) and a second toothed sidewall that matches the shape of the second toothed surface (142) of the tenon (14). There is a first toothed fit gap between the first toothed surface (141) and the first toothed sidewall, and there is a second toothed fit gap between the second toothed surface (142) and the second toothed sidewall. The toothed depth of the first toothed fit gap is greater than the toothed depth of the second toothed fit gap.

4. The runner of the impulse turbine as described in claim 1, characterized in that, The lower end of the tenon (21) is provided with a centrifugal sand discharge chute (211). The centrifugal sand discharge chute (211) is configured to use the centrifugal force generated when the wheel rotates to throw out the mud and sand that may enter the gap between the tenon (14) and the mortise (21).

5. The runner of the impulse turbine as described in claim 1, characterized in that, The water-dividing blade (123) of the water bucket blade (15) is integrally formed from carbon fiber composite material on the back water surface layer (12). The back water surface layer (12) has edge grooves (124) extending inward on both sides. The water-dividing blade (123) has water-dividing blade grooves (125) on both sides. The water-facing surface layer (11) is snapped and fixed between the edge grooves (124) and the water-dividing blade grooves (125).

6. The runner of the impulse turbine as described in claim 1, characterized in that, The water-facing surface layer (11) and the back-facing surface layer (12) are connected by an anchoring limit bolt (126). The anchoring limit bolt (126) penetrates the back-facing surface layer (12) and is connected to the water-facing surface layer (11). The head of the anchoring limit bolt (126) is equipped with a curved gasket (127) that fits the curved surface of the back-facing surface layer (12). The anchoring limit bolt (126) is located in the back-facing groove of the water-dividing blade (123) and / or in the thick wall of the water bucket (1).

7. An impulse turbine, characterized in that, Includes the impeller, water distribution coil (5) and nozzle (3) connected to the water distribution coil (5) as described in any one of claims 1 to 6; The inner wall of the nozzle (3) is provided with helical rifling (31). The spiral rifling (31) is used to generate rotation of the high-speed water flow passing through the nozzle (3) so as to separate the mud and sand in the water flow by centrifugal force.

8. The impulse turbine as described in claim 7, characterized in that, The spiral rifling (31) is a gradually decreasing rifling, and the pitch of the spiral rifling (31) gradually decreases along the direction of water flow. The spiral rifling (31) includes alternating positive rifling (311) and negative rifling (312), which extend spirally along the axial direction of the nozzle (3); The inner wall of the nozzle (3) is provided with spiral ridges, which form the male line (311), and the inner wall surfaces between adjacent spiral ridges form the female line (312); or The inner wall of the nozzle (3) is provided with a spiral groove, which forms the negative line (312), and the inner wall surface between adjacent spiral grooves forms the positive line (311).

9. The impulse turbine as described in claim 7, characterized in that, The working surface of the water bucket (1) of the impeller is provided with a partitioned additive layer (118), the position of which corresponds to the mud and sand impact area on the outer edge of the jet after being treated by the spiral rifling (31).

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