Pelton turbine, runner and method for assembling a runner

Abstract

The application provides an impulse water turbine, a runner and an assembling method of the runner. The runner comprises a hub, a thrust pad base and a water bucket. A plurality of the thrust pad bases are arranged along the outer circumference of the hub in a ring shape. The thrust pad base and the hub are assembled by interference through a mortise and tenon joint structure. At least one water bucket is assembled on each thrust pad base. The thrust pad base and the water bucket are assembled by interference through a mortise and tenon joint structure. A pre-tightening force is applied through interference fit to assemble the three rotating components of the impulse water turbine, i.e. the water bucket, the thrust pad base and the hub, into a large-size, high-strength and high-rigidity integrated runner. The application can effectively solve the problems of insufficient rigidity and strength of the welding joint structure of the large-size, high-head, high-speed and large-size runner water bucket and hub of the large-size impulse water turbine and the manufacturing difficulty of the large-size hub, so that a large-size, high-thickness, large-outer-diameter, high-reliability and easy-to-repair-and-replace large-size impulse water turbine becomes possible.

Description

Technical Field

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

[0002] Under high head conditions, especially those exceeding 700m, impulse turbines are generally used. The hubs of large-capacity, high-speed impulse turbines require extremely high strength to withstand the pulsating loads and water thrust generated by the turbine runner under high-speed jet flow. Manufacturing large-diameter hubs exceeding 4m in height has always been a design, operational, and manufacturing challenge in the industry. Particularly under conditions of high sediment loads and large capacities, the speed of impulse turbines is increasing, and the size of the buckets is also growing. With the combined effects of increased runner diameter, rising speed, and larger bucket dimensions, the hub dimensions and rigidity achieved using traditional welding methods are insufficient to meet the requirements for long-term safe and stable operation of impulse turbines. Under high head and sediment conditions, this can easily lead to deformation and cracking at the connection root between the buckets and the hub, or even bucket breakage and hub damage. Summary of the Invention

[0003] To address the problem described in the background art that the connection between the bucket and the hub is prone to deformation and cracking, or even bucket breakage and hub damage, under high water head and high sediment conditions, this application provides an impulse turbine, a runner, and an assembly method for the runner. By applying preload through interference fit, the three major rotating components of the impulse turbine—the bucket, the thrust bearing base, and the hub—are assembled into a large-size, high-strength, and high-rigidity integral runner.

[0004] The first aspect of this application provides an impulse turbine runner, including a hub, a thrust bearing base, and a water bucket; a plurality of the thrust bearing bases are arranged in a ring along the outer circumference of the hub, and the thrust bearing bases and the hub are interference-fitted by a tenon and mortise connection structure; at least one water bucket is mounted on each of the thrust bearing bases, and the thrust bearing bases and water buckets are interference-fitted by a tenon and mortise connection structure.

[0005] Furthermore, the interference fit is divided into two or more levels from the inside out according to the hub, thrust bearing base, and water bucket. The interference fit gaps of each level are symmetrically and evenly distributed along the outer circumference of the runner component.

[0006] Furthermore, the preload force, total length of assembly gap, circumferential interference fit area, and axial interference fit area of ​​each stage of the interference fit are selected and determined based on the head, capacity, speed, and number of buckets of the impulse turbine.

[0007] Furthermore, the outer circumference of the wheel hub is uniformly provided with multiple wheel hub tenons, and the root of the thrust bearing base is provided with a base root tenon, which is interference-fitted into the wheel hub tenon.

[0008] Furthermore, the tenon at the base root is provided with two toothed surfaces, and the tenon groove of the hub is provided with toothed sidewalls that are interference fit with the tenon at the base root.

[0009] Furthermore, the top of the thrust bearing base is provided with at least one base tenon groove, and the root of the water bucket is provided with a water bucket tenon, which is interference-fitted into the base tenon groove.

[0010] Furthermore, the water bucket tenon has a first toothed surface on the water-facing side and a second toothed surface on the water-repellent side along the rotation direction of the wheel after assembly, and the first toothed surface and the second toothed surface have different tooth profile parameters; the base tenon groove is provided with a toothed sidewall that is interference-fitted with the water bucket tenon.

[0011] Furthermore, the upper surface of the first tooth surface has a first inclination angle, and the upper surface of the second tooth surface has a second inclination angle, wherein the first inclination angle is greater than the second inclination angle; and the tooth depth of the first tooth surface is greater than the tooth depth of the second tooth surface.

[0012] The second aspect of this application provides a method for assembling an impulse turbine runner, comprising:

[0013] Multiple thrust bearing bases are interference-fitted onto the outer circumference of the hub using a mortise and tenon joint structure. The thrust bearing bases are connected end to end along the outer circumference of the hub without gaps and form a complete ring.

[0014] The water bucket is interference-fitted onto the thrust bearing base using a mortise and tenon joint structure.

[0015] A third aspect of this application provides an impulse turbine, including the aforementioned runner, distribution coil, and nozzles connected to the distribution coil.

[0016] This application describes an impulse turbine runner that uses a component-by-component, graded, and interference-fit assembly method to tightly assemble the buckets, thrust bearing base, and hub into a high-strength, highly adaptable, and high-speed whole. The buckets and the overall profile do not require welding, resulting in extremely high overall rigidity and strength. The entire runner exhibits excellent adaptability to ultra-high buckets, ultra-large thrust loads, and high speeds, solving the problem of easy deformation, failure, or even bucket breakage at the hub root under ultra-high head and ultra-strong jet impact. It can well adapt to the operating conditions of impulse runners with ultra-high heads (such as 1000m class), larger capacities (such as 700MW and above), and high silt content (especially high content of hard silt). This invention also solves the problems of load transfer and hydraulic stability in ultra-high head, ultra-large capacity impulse turbine runners. Furthermore, the assembly structure of the bucket and thrust bearing base significantly reduces the requirements for the hub outer diameter while improving the overall rigidity of the runner. Since all components are assembled, operation, maintenance, and repair offer unparalleled convenience, thus comprehensively improving the runner's hydraulic performance in terms of reliability, safety, and operational flexibility. This application effectively solves the design, manufacturing, and operational challenges and limitations of ultra-high head, ultra-large capacity, high speed, and large-size impulse turbine runners from a structural, methodological, and principle perspective, making it possible to develop larger, thicker, larger-diameter, more reliable, and easier-to-maintain large-scale impulse bucket turbines. The technical solution of this application addresses the challenges of insufficient rigidity and strength of the welded connection structure of the large-size runner, bucket, and hub in large impulse turbines, which are characterized by high head, high speed, and large size. It not only enables the design and manufacture of impulse turbines with larger runner outer diameters but also takes into account the overall rigidity of the runner and the convenience of operation, maintenance, and replacement of components. Attached Figure Description

[0017] 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.

[0018] Figure 1 This is a schematic diagram of the structure of an impulse turbine provided in an embodiment of this application.

[0019] Figure 2 This is a perspective view of the structure of an impulse turbine runner provided in an embodiment of this application.

[0020] Figure 3 This is a front view of the structure of an impulse turbine runner provided in an embodiment of this application.

[0021] Figure 4 This is an enlarged view of the structure of an impulse turbine runner provided in an embodiment of this application.

[0022] Figure 5 This is a schematic diagram of the connection structure of the thrust bearing base of an impulse turbine runner provided in an embodiment of this application.

[0023] Figure 6 This is a schematic diagram of the bucket connection structure of an impulse turbine runner provided in an embodiment of this application.

[0024] Figure 7 The diagram shows the calculation of key parameters and logical relationship of interference fit provided in an embodiment of this application.

[0025] Explanation of reference numerals in the attached drawings: 1-Water bucket; 11-Water-facing surface; 12-Water-repellent surface; 14-Water bucket tenon; 141-First toothed surface; 142-Second toothed surface; 2-Hub; 21-Hub tenon; 3-Nozzle; 4-Thrust bearing base; 41-Base tenon; 42-Base root tenon; 5-Water distribution coil. Detailed Implementation

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] like Figure 1 As shown in the embodiment of this application, an impulse turbine includes a runner, a water distribution coil 5, and a nozzle 3 connected to the water distribution coil 5.

[0034] Generally, the hub 2 is an intermediate component connecting the bucket 1 of an impulse turbine runner and the main shaft, serving to transmit torque and support the bucket. The bucket 1 generates rotational torque due to the force of the water flow, which is transmitted to the main shaft through the hub, thereby driving the generator rotor to rotate and convert water energy into electrical energy. The bucket 1 is a key component for withstanding the impact of the water flow and converting water energy into mechanical energy. It typically consists of bucket blades, a bucket back, and a water-dividing blade, evenly distributed around the circumference of the hub 2. The bucket blades of the bucket 1 are double-bowl or spoon-shaped, with a specific curvature and shape to adapt to the impact of the water flow and energy conversion. The water-dividing blade is located at the center of the bucket 1, dividing the jet into two parts, which enter the two halves of the bucket 1 respectively. When high-speed water is ejected from the nozzle 3 and impacts the water-dividing blade of the bucket, the water flow is divided into two parts, which enter the two halves of the bucket 1 respectively. As water flows within the water bucket 1, its speed and direction change due to the shape and curvature of the bucket, generating an impact force. This impact force drives the bucket 1 to rotate via the hub 2, which in turn drives the turbine runner and main shaft, converting the kinetic energy of the water flow into mechanical energy. The water bucket 1 is typically made of high-strength, high-toughness materials, such as stainless steel, to withstand the impact and wear of the high-speed water flow. The main function of the nozzle 3 is to convert the pressure energy of the water into kinetic energy, forming a high-speed jet that impacts the turbine runner, causing it to rotate and thus converting water energy into mechanical energy. The high-speed water flow ejected from the nozzle 3 forms an impact jet. This jet, with its pressure and velocity, impacts the turbine runner, causing it to rotate and perform work, thereby converting water energy into mechanical energy. The speed of the impact jet can reach tens of meters per second or even higher to effectively impact the runner and transfer energy.

[0035] like Figure 2 and Figure 3 As shown in the embodiment of this application, an impulse turbine runner is provided, comprising a hub 2, a thrust bearing base 4, and water buckets 1. Multiple thrust bearing bases 4 are arranged in a ring along the outer circumference of the hub 2, and the thrust bearing bases 4 and hub 2 are interference-fitted via a mortise and tenon joint. Each thrust bearing base 4 is fitted with two water buckets 1, and the thrust bearing base 4 and water buckets 1 are interference-fitted via a mortise and tenon joint. Thus, by applying preload through the interference fit, the three major rotating components of the impulse turbine—water buckets 1, thrust bearing bases 4, and hub 2—are assembled into a large-size, high-strength, and high-rigidity integral runner.

[0036] In one embodiment, such as Figure 5 As shown, the outer circumference of the hub 2 is evenly provided with multiple hub tenon grooves 21, and the root of the thrust bearing base 4 is provided with a base root tenon 41, which is interference-fitted into the hub tenon groove 21.

[0037] In one embodiment, the tenon 41 at the base root is provided with two toothed surfaces, and the hub tenon 21 is provided with a toothed sidewall that is interference-fitted with the tenon 41 at the base root.

[0038] In one embodiment, such as Figure 6 As shown, the top of the thrust bearing base 4 is provided with two base tenons 41, and the root of the water bucket 1 is provided with a water bucket tenon 14, which is interference-fitted into the base tenons 41. Thus, two water buckets 1 can be interference-fitted onto the thrust bearing base 4.

[0039] In one embodiment, the water bucket tenon 14 has a first toothed surface 141 on the water-facing side and a second toothed surface 142 on the water-repellent 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 base tenon groove 41 is provided with a toothed sidewall that is interference-fitted with the water bucket tenon 14.

[0040] In this embodiment, the tenon and mortise connection structure between the thrust bearing base 4 and the hub 2, and the tenon and mortise connection structure between the thrust bearing base 4 and the water tank 1, both adopt tooth-shaped structures, which significantly increase the contact area after assembly, allowing the impact load to be uniformly transmitted through multiple tooth surfaces, effectively dispersing stress concentration. At the same time, the tooth-shaped interlocking effect can also generate a self-locking effect during high-speed rotation, enhancing the stability of the connection.

[0041] In application, the toothed structure of the tenon-and-mortise connection between the thrust bearing base 4 and the water bucket 1 has larger teeth on the water-facing side and smaller teeth on the water-repellent side. This fit clearance method allows for adjustment of the length of the toothed gap occupied by the tenon in the mortise groove according to the magnitude of the jet impact load under different working conditions (i.e., different water heads). That is, the greater the jet impact load, the deeper the tenon enters the mortise groove, and the larger the proportion of the toothed fit clearance occupied.

[0042] 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.

[0043] In one embodiment, the upper surface of the first tooth surface 141 has a first tilt angle θ1, and the upper surface 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; and the tooth depth of the first tooth surface 141 is greater than the tooth depth of the second tooth surface 142.

[0044] In applications, the toothed surfaces of the mortise and tenon structure are asymmetrically distributed along the rotation direction of the wheel (θ1 > θ2). Under an interference fit, an additional biting force generated by the centrifugal force of the rotating wheel can be obtained. This 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 can be greater than the impact force of the nozzle jet. Together with the preload generated by the interference fit, it can meet the requirements of a firm and stable connection and long-term safe and stable operation of the water bucket and hub under high-speed rotation and ultra-high torque conditions.

[0045] like Figure 3 and Figure 4 As shown, the interference fit in this application is divided into two-stage or multi-stage configurations from the inside out, based on the hub 2, thrust bearing base 4, and water bucket 1. The choice between two-stage or multi-stage configurations can be made as needed. The interference fit clearances of each stage are symmetrically distributed along the circumference of the runner components, such as the hub inner diameter r1, hub outer diameter r2, thrust bearing inner diameter r3, thrust bearing outer diameter r4, water bucket center outer diameter r4, and water bucket maximum outer diameter r5. The preload, total length of the assembly clearance, circumferential interference fit area, and axial interference fit area of ​​each stage are selected and determined based on the head, capacity, speed, and number of water buckets of the impulse turbine.

[0046] The calculation of key parameters and logical relationship diagram for interference fit are as follows: Figure 7 As shown.

[0047] In one embodiment, such as Figure 3 As shown, in the interference fit, the first-level gap δ1 between the hub and the thrust bearing base is made of high-strength stainless steel or forged steel on the non-driving end, i.e., the back side of the connecting water bucket, in the direction of the wheel rotation. It is a thick tile and combines with the second-level gap δ2 between the thrust bearing base and the water bucket to form the connecting base of the water bucket.

[0048] In one embodiment, such as Figure 3 As shown, in the interference fit, the thrust bearing base-water bucket secondary graded gap δ2 is the Babbitt alloy material with a good elastic coefficient on the drive end, i.e., the water-facing side of the water bucket, of the thrust bearing base 4 according to the rotation direction of the wheel. It is a thin tile and is combined with the hub-thrust bearing base primary graded gap δ1 to form the connecting base of the water bucket.

[0049] In one embodiment, the circumferential interference fit area S cj and its torque T cj : For first-level (j=1), second-level (j=2...) circumferential gap cylindrical surfaces (S cjThe torque (T) generated by j=1, 2... cj (j=1, 2...), T cj And it can be calculated using the following formula:

[0050] T cj = 2πμ P j b j r j 2 k j ,

[0051] In the formula, μ is the coefficient of friction, P j For contact pressure, b j The axial length of the cylindrical surface, r j Let k be the average radius of the cylindrical surface. j This is the correction factor for the cylindrical surface.

[0052] In one embodiment, the axial interference fit area S aj and its torque T aj : For the first-level (j=1), second-level (j=2...) radial line gap end face (S aj The torque (T) generated by j=1, 2... aj (j=1, 2...), T aj And it can be calculated using the following formula:

[0053] T aj = (2π / 3) μ P j (r o,j 3 -r i,j 3 )λ j ,

[0054] In the formula, μ is the coefficient of friction, P j For contact pressure, r o,j r is the outer radius of the end face. i,j Let λ be the inner radius of the end face. j This is the end face correction factor.

[0055] In one embodiment, the interference fit geometry / friction coefficient C j : This is the linear proportionality coefficient of pressure-torque for each level of interference fit, determined by the torque generated by the cylindrical surface and end face of the interference fit gap at each level, and can be calculated by the following formula:

[0056] .

[0057] Example 1

[0058] Taking a super-high head, large-capacity impulse turbine (Z=24) with a head of 1000m and a single unit capacity of 800MW as an example, this application can achieve high adaptability, high strength, and high safety and reliability of the bucket-thrust bearing base-hub structure. The specific implementation is as follows:

[0059] Pick The specific speed is taken from the commonly used range of the Pelton engine. (metric), the solution is:

[0060] ,

[0061] ,

[0062] ,

[0063] Select a set of structural radii for initial calculations: .

[0064] Take the coefficient of friction Let the axial contact width of the two levels be... Enlarged tooth area end face coverage (Common values ​​when the torus is not in full contact).

[0065] Then there are area and line spacing:

[0066] ,

[0067] ,

[0068] The gap length is taken as ;

[0069] ,

[0070] ,

[0071] .

[0072] Torsional coefficient (constant term):

[0073] ,

[0074] .

[0075] Substituting the dimensions above, we get and (Unit: N·m / Pa)

[0076] Torque requirement:

[0077] ,

[0078] If a safety factor is taken The two pressure levels are the same. ,but

[0079] .

[0080] Based on this, the total preload at each level is obtained:

[0081] ,

[0082] ,

[0083] Total torsional capacity:

[0084] ,

[0085] Required interference ( )

[0086] The above-mentioned two-stage configuration, with a bus gap of 120.35m, generates a total torsional capacity of 145.8MN·m, which meets the total torque requirement of a 1000m head, 800MW impulse turbine under a safety factor of 3. This enables the high adaptability, high strength, and high safety and reliability of the bucket-thrust bearing base-hub structure.

[0087] 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. An impulse turbine runner, characterized in that: It includes a hub (2), a thrust bearing base (4), and a water bucket (1); multiple thrust bearing bases (4) are arranged in a ring along the outer circumference of the hub (2), and the thrust bearing bases (4) are connected end to end along the outer circumference of the hub (2) to form a complete ring. The thrust bearing bases (4) and the hub (2) are interference-fitted by a mortise and tenon connection structure. At least one water bucket (1) is installed on each thrust bearing base (4), and the thrust bearing bases (4) and the water buckets (1) are interference-fitted by a mortise and tenon connection structure. The interference fit is divided into two or more levels from the inside out according to the hub (2), thrust bearing base (4), and water bucket (1). The interference fit gap of each level is symmetrically distributed along the outer circumference of the wheel component. The outer circumference of the hub (2) is uniformly provided with multiple hub tenon grooves (21), and the root of the thrust bearing base (4) is provided with a base root tenon (42), which is interference-fitted into the hub tenon groove (21). The top of the thrust bearing base (4) is provided with at least one base tenon groove (41), and the root of the water bucket (1) is provided with a water bucket tenon (14). The water bucket tenon (14) is interference-fitted into the base tenon groove (41). The water bucket tenon (14) has a first toothed surface (141) on the water-facing side and a second toothed surface (142) on the water-returning side of the water bucket along the rotation direction of the wheel after its assembly. The first toothed surface (141) and the second toothed surface (142) have different tooth profile parameters. The base tenon groove (41) is provided with a toothed sidewall that is interference-fitted with the water bucket tenon (14).

2. The impulse turbine runner as described in claim 1, characterized in that: The preload force, total length of assembly gap, circumferential interference fit area, and axial interference fit area of ​​each stage of the interference fit are selected and determined based on the head, capacity, speed, and number of buckets of the impulse turbine.

3. The impulse turbine runner as described in claim 1, characterized in that: The base root tenon (42) is provided with two toothed surfaces, and the hub tenon groove (21) is provided with a toothed sidewall that is interference fit with the base root tenon (42).

4. The impulse turbine runner as described in claim 1, characterized in that: The upper surface of the first tooth surface (141) has a first inclination angle, and the upper surface of the second tooth surface (142) has a second inclination angle. The first inclination angle is greater than the second inclination angle. The tooth depth of the first tooth surface (141) is greater than the tooth depth of the second tooth surface (142).

5. A method for assembling an impulse turbine runner as described in any one of claims 1-4, characterized in that, include: Multiple thrust bearing bases (4) are interference-fitted onto the outer circumference of the hub (2) through a mortise and tenon connection structure. The thrust bearing bases (4) are connected end to end along the outer circumference of the hub (2) without gaps and form a complete ring. The water bucket (1) is assembled onto the thrust bearing base (4) by means of a tenon and mortise joint structure.

6. An impulse turbine, characterized in that: It includes the impeller, the water distribution coil (5) as described in any one of claims 1-4, and the nozzle (3) connected to the water distribution coil (5).

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