Hydraulic model of shielding motor nuclear main pump and shielding motor nuclear main pump

Abstract

The invention relates to the technical field of vane pumps, and provides a shield motor nuclear main pump hydraulic model and a shield motor nuclear main pump. The shielding motor nuclear main pump hydraulic model comprises an impeller, wherein blades of the impeller are blades of a line element three-dimensional structure; the guide vane is matched with the impeller, and blades of the guide vane are blades of a linear element three-dimensional structure; the pump shell is matched with the guide vane; the appearance of the line element three-dimensional structure blade is determined through two sets of curve elements located on the front cover plate and the rear cover plate, and the curve elements comprise a front edge line, a tail edge line, a pressure surface line and a suction surface line. According to the line element three-dimensional structure blade, a front edge line, a tail edge line, a pressure surface line and a suction surface line of a front cover plate and a rear cover plate are generated on the basis of parameterized meridian curve, mean camber line angle distribution and thickness distribution, and a continuous curved surface is constructed through a lofting method, a sweeping method or a grid method. The linear element three-dimensional structure blade can be integrally milled, so that the material utilization rate, the machining efficiency and the machining quality are improved, and the casting defects are overcome.

Description

Technical Field

[0001] This application relates to the field of vane pump technology, and more specifically, to a hydraulic model of a shielded motor core main pump and a shielded motor core main pump. Background Technology

[0002] The Major Project for Large-Scale Advanced Pressurized Water Reactor Nuclear Power Plants, or "Pressurized Water Reactor Major Project" for short, aims to develop a brand of large-scale advanced pressurized water reactor nuclear power technology with independent intellectual property rights and greater power output by digesting, absorbing, and fully mastering the advanced third-generation nuclear power AP1000 technology introduced from abroad, and through further innovation and development.

[0003] Currently, there is no hydraulic model for nuclear main pumps that differs from the AP1000 technology, and no high-efficiency hydraulic model for nuclear main pumps with independent intellectual property rights has emerged after the power output was increased from 1 million kilowatts to 1.4 million kilowatts. This model faces multiple constraints, including: a 21% increase in flow rate compared to the AP1000, a relatively unchanged head, a 1.2% increase in hydraulic efficiency, a 32.6% reduction in required net positive suction head (NPSH), a 17% decrease in rotational speed, a 7.3% increase in the outer diameter limit, an 8.0% increase in the pump casing inlet diameter, a 16.3% increase in the outlet diameter, and an axial force of less than 23 tons.

[0004] Existing impellers have numerous problems, such as a large number of blades and numerous casting defects due to the casting process. Particularly in areas with significant alternating stress changes at the blade leading edge, even after repair, casting defects can easily lead to blade fatigue failure, resulting in unit malfunctions and shutdowns, failing to meet the 60-year lifespan design requirement of the main pump. Furthermore, the existing point-element three-dimensional blades are difficult and costly to manufacture, and cannot be completed using integral CNC machining methods. Summary of the Invention

[0005] To address the technical challenges of machining the three-dimensional blades of the hydraulic model points of the aforementioned nuclear main pump, which is difficult and results in numerous casting defects when using casting, this application proposes a shielded motor-driven hydraulic model for a nuclear main pump.

[0006] The second aspect of this application proposes a shielded motor nuclear main pump.

[0007] In view of this, the first aspect of this application proposes a hydraulic model for a shielded motor nuclear main pump, comprising: an impeller for mounting on the shaft of the shielded motor nuclear main pump, the blades of the impeller being three-dimensional linear element blades; a guide vane, cooperating with the impeller, the blades of the guide vane being three-dimensional linear element blades; and a pump casing, cooperating with the guide vane; wherein, the shape of the three-dimensional linear element blades is determined by two sets of curve elements located on the front and rear cover plates, the curve elements including the leading edge line, trailing edge line, pressure surface line, and suction surface line, described by the meridional curve, the mid-arc angle distribution, and the thickness distribution; the three-dimensional linear element blades generate the leading edge line, trailing edge line, pressure surface line, and suction surface line of the front and rear cover plates based on the parameterized meridional curve, the mid-arc angle distribution, and the thickness distribution, and construct continuous surfaces by lofting, sweeping, or meshing methods.

[0008] In conjunction with the first aspect, in some feasible embodiments, the impeller includes: impeller blades, an impeller front cover plate, and an impeller rear cover plate, the impeller front cover plate and the impeller rear cover plate being located on both sides of the impeller blades, the impeller blades including four blades circumferentially spaced along the axis of rotation.

[0009] In conjunction with the first aspect, in some feasible methods, the blade wrap angle α on the rear cover side and the blade wrap angle β on the front cover side of each impeller blade satisfy the following relationship: 28°≤α-β≤30°; where α is the angle between the leading edge and trailing edge of the profile at the rear cover and the impeller shaft center on the axial projection, and β is the angle between the leading edge and trailing edge of the profile at the front cover and the impeller shaft center on the axial projection.

[0010] In conjunction with the first aspect, in some feasible ways, the impeller is a mixed-flow impeller.

[0011] In conjunction with the first aspect, in some feasible embodiments, the guide vane includes: a guide vane blade, a guide vane front cover plate, and a guide vane rear cover plate, the guide vane front cover plate and the guide vane rear cover plate being located on both sides of the guide vane blade, the guide vane blade including N blades circumferentially spaced along the axis of rotation, where N satisfies: 7≤N≤11, and N is a positive integer.

[0012] In conjunction with the first aspect, in some feasible ways, the exit blade angle of the guide vane includes the exit angle A of the guide vane front cover plate and the exit angle B of the guide vane rear cover plate, satisfying the following relationship: 44°≤A≤46°, 44°≤B≤46°.

[0013] In conjunction with the first aspect, in some feasible methods, the guide vane exit angle γ satisfies the following relationship: -14°≤γ≤+9°; where the guide vane exit angle γ is the angle between the line connecting the centers of the trailing edges of the guide vane front cover and the guide vane rear cover and a straight line passing through the center of the trailing edge of the guide vane rear cover and parallel to the axis of rotation.

[0014] In conjunction with the first aspect, in some feasible ways, the difference between the wrap angle D of the guide vane rear cover and the wrap angle C of the guide vane front cover satisfies the following relationship: 9°≤DC≤11°.

[0015] In conjunction with the first aspect, in some feasible embodiments, the pump casing includes a spherical body and an outlet cylinder protruding from the outer surface of the spherical body, the spherical body and the outlet cylinder being connected by a tapering structure from approximately rectangular to circular.

[0016] The second aspect of this application proposes a shielded motor nuclear main pump, comprising: a shielded motor nuclear main pump hydraulic model as described in any of the above technical solutions.

[0017] Compared with related technologies, this application has the following technical advantages: The shielded motor nuclear main pump hydraulic model provided in this application is a high-power shielded motor nuclear main pump hydraulic model that can be milled as a whole under multiple constraints. The impeller and guide vane blades are three-dimensional structure blades with linear elements. The three-dimensional structure blades with linear elements can be milled as a whole, which improves material utilization, processing efficiency and processing quality, and overcomes casting defects.

[0018] Additional aspects and advantages of this application will become apparent in the following description or may be learned by practice of this application. Attached Figure Description

[0019] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This paper shows a schematic diagram of the structure of a shielded motor core pump hydraulic model according to one embodiment of the present application; Figure 2 A schematic diagram of the impeller structure in one embodiment of this application is shown; Figure 3 A schematic diagram of the guide vane in one embodiment of this application is shown; Figure 4 This illustration shows one of the structural schematic diagrams of the water outlet cylinder in one embodiment of this application; Figure 5 This is a second schematic diagram of the structure of the water outlet cylinder in one embodiment of this application; Figure 6 The third schematic diagram of the water outlet cylinder in one embodiment of this application is shown; Figure 7 A schematic diagram of the blade distribution structure of a guide vane in one embodiment of this application is shown; Figure 8 A schematic diagram of the structure of the blades of an impeller in one embodiment of this application is shown; Figure 9A comparative schematic diagram of a line element three-dimensional structure blade and a point element three-dimensional structure blade in one embodiment of this application is shown; Figure 10 A comparative schematic diagram of a line element three-dimensional structure blade impeller and a point element three-dimensional structure blade impeller in one embodiment of this application is shown; Figure 11 One schematic diagram of the guide vane outlet in one embodiment of this application is shown; Figure 12 A second schematic diagram of the guide vane outlet in one embodiment of this application is shown; Figure 13 This is shown as a third schematic diagram of the guide vane outlet in one embodiment of this application.

[0020] in, Figures 1 to 13 The correspondence between the reference numerals and component names in the attached drawings is as follows: 1 Impeller, 2 Guide vane, 3 Pump casing, 4 Impeller front cover plate, 5 Impeller rear cover plate, 6 Guide vane front cover plate, 7 Guide vane rear cover plate, 8 Water outlet cylinder, 9 Linear element three-dimensional structure blade, 10 Point element three-dimensional structure blade. Detailed Implementation

[0021] To better understand the above-mentioned objectives, features, and advantages of this application, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0022] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below.

[0023] The following reference Figures 1 to 13 The present application describes a hydraulic model of a shielded motor core pump and a shielded motor core pump according to some embodiments.

[0024] like Figure 1As shown, the first aspect of this application proposes a hydraulic model of a shielded motor nuclear main pump, comprising: an impeller 1 for mounting on the shaft of the shielded motor nuclear main pump, the blades of the impeller 1 being three-dimensional linear element blades 9; a guide vane 2, cooperating with the impeller 1, the blades of the guide vane 2 being three-dimensional linear element blades 9; and a pump casing 3, cooperating with the guide vane 2. The shape of the three-dimensional linear element blades 9 is determined by two sets of curve elements located on the front and rear cover plates. The curve elements include leading edge lines, trailing edge lines, pressure surface lines, and suction surface lines, described by meridional curves, mid-arc angle distributions, and thickness distributions. Based on the parameterized meridional curves, mid-arc angle distributions, and thickness distributions, the three-dimensional linear element blades 9 generate leading edge lines, trailing edge lines, pressure surface lines, and suction surface lines on the front and rear cover plates, constructing continuous surfaces through lofting, sweeping, or meshing methods.

[0025] The hydraulic model of the shielded motor nuclear main pump provided in this application includes an impeller 1, guide vanes 2, and a pump casing 3. The blades of the impeller 1 and guide vanes 2 adopt a three-dimensional structure of linear elements, and their shape is determined by two sets of curved elements located on the front and rear cover plates. The blades of the impeller 1 and guide vanes 2 are changed from point element three-dimensional blades 10 in related technologies to line element three-dimensional structure blades 9. On the one hand, this can increase the machinability of the impeller 1 and guide vanes 2. The line element three-dimensional structure blades 9 are easier to mill. Milling can overcome many casting defects of casting processing methods. Moreover, the milling method can increase the accuracy of the internal flow channels and blade profiles of the impeller 1 and guide vanes 2, ensuring the performance of the main pump. On the other hand, compared with point element three-dimensional blades 10, line element three-dimensional structure blades 9 can greatly reduce the processing cost.

[0026] The blade is constructed based on parametric meridional curves, mid-arc angle distribution, and thickness distribution, which allows designers to easily adjust and optimize various blade parameters to adapt to different operating conditions and performance requirements, thus enhancing the flexibility and adaptability of the design.

[0027] By using lofting, sweeping, or meshing methods to construct continuous curved surfaces to form blades, compared to traditional blade construction methods, it is possible to more accurately achieve complex blade shape design, ensure the smoothness and continuity of the blade surface, reduce fluid separation and eddy current generation on the blade surface, and further improve pump performance and stability.

[0028] like Figure 9 and Figure 10As shown, it can be understood that replacing the point element 3D blade 10 with a line element 3D structure blade 9 means approximating a complex point element 3D blade 10 with a series of sequentially arranged 2D straight line segments, i.e., line elements. These straight line segments are "placed" in the correct positions in space, and then the final 3D blade entity is generated through operations such as "sweeping". This is a method that simplifies the modeling process while retaining key geometric features. Specifically, the shape of the blade root and tip, as well as their 3D spatial positions, are first determined. The complex curved surface of the blade is "decomposed" into many small ruled surfaces. It's like using many thin, long ruler pieces, piece by piece, to assemble a curved fan blade shape. Using these small ruler pieces as a skeleton, they are allowed to "grow" curved surfaces from the leading edge to the trailing edge. Then, these curved surfaces are "attached" to the surfaces of the blade root, tip, and tail to form a solid, voluminous blade. The blade root corresponds to the blade's rear cover plate, and the blade tip corresponds to the blade's front cover plate. The specific method is summarized as follows: Input: Meridian outlines of the front and rear cover plates + two 2D leaf shapes attached to the root and top.

[0029] Method: The curved surface of the blade is discretized using a large number of controllable two-dimensional straight line segments.

[0030] Process: Surfaces are generated through sweeping operations of these line elements.

[0031] Output: Stitch these surfaces with the boundary surfaces to generate a 3D solid blade model that can be used for machining and analysis.

[0032] In practical applications, the line element 3D structure blade 9 typically refers to a 3D blade model constructed using line elements. These line elements can be curves or straight lines. The core principle is to define the blade's profile along its height using parametric or geometric constraint methods. The point element 3D blade 10 describes the blade's profile along its height using discrete point clouds, preserving high-precision geometric details across multiple sections from the blade root to the blade tip, such as wrinkles and holes. However, it involves a large amount of data, lacks explicit structural information, making it difficult and costly to manufacture, and it is impossible to complete using a single milling method.

[0033] The shielded motor nuclear main pump hydraulic model provided in this application is a high-power shielded motor nuclear main pump hydraulic model that can be milled as a whole under multiple constraints. The blades of the impeller 1 and guide vane 2 adopt the three-dimensional structure blade 9 of line element. The three-dimensional structure blade 9 of line element can be milled as a whole, which improves the material utilization rate, processing efficiency and processing quality, and overcomes casting defects.

[0034] like Figure 1 and Figure 2As shown, in some embodiments provided in this application, the impeller 1 includes: impeller blades, an impeller front cover plate 4 and an impeller rear cover plate 5. The impeller front cover plate 4 and the impeller rear cover plate 5 are located on both sides of the impeller blades. The impeller blades include four blades arranged circumferentially along the axis of rotation.

[0035] In this embodiment, the impeller 1 includes impeller blades, an impeller front cover plate 4, and an impeller rear cover plate 5. The impeller blades consist of four blades spaced circumferentially along the shaft axis, and the blades are linear element three-dimensional structure blades 9 formed by the airfoil control on both sides of the impeller front cover plate 4 and the impeller rear cover plate 5. This design enables more precise control of the flow direction and velocity distribution of the fluid within the impeller 1, allowing the fluid to achieve more ideal energy conversion within the impeller 1, reducing energy loss, and improving the head and efficiency of the nuclear main pump.

[0036] The three-dimensional blade 9, with its linear element structure, is formed by the combined control of the blade profiles on both sides of the impeller front cover plate 4 and the impeller rear cover plate 5. This structure provides good support for the blade in both the circumferential and axial directions, enhancing the overall strength and rigidity of the impeller 1. Under high-speed rotation and complex operating conditions, it can effectively resist the impact force and centrifugal force of the fluid, reduce the deformation and vibration of the impeller 1, and improve operational stability.

[0037] By adjusting the blade profile of the impeller front cover plate 4 and the impeller rear cover plate 5, as well as the impeller blade parameters, the pump performance curve can be changed to a certain extent, enabling the hydraulic model to adapt to different flow rates, head, and other operating conditions, thus possessing a certain degree of versatility and flexibility.

[0038] like Figure 8 As shown, in some embodiments provided in this application, the blade wrap angle α on the rear cover plate side and the blade wrap angle β on the front cover plate side of each impeller 1 satisfy the following relationship: 28°≤α-β≤30°; where α is the angle between the leading edge point and trailing edge point of the profile at the rear cover plate and the impeller shaft center on the axial plane projection, and β is the angle between the leading edge point and trailing edge point of the profile at the front cover plate and the impeller shaft center on the axial plane projection.

[0039] In this embodiment, the blade wrap angle α on the rear cover plate side and the blade wrap angle β on the front cover plate side of each impeller 1 satisfy the following relationship: 28°≤α-β≤30°, and both angles α and β are small, which has good machinability and can meet the overall milling process requirements of impeller 1, as well as the requirements of high efficiency, high stability and reliability of impeller 1.

[0040] In some embodiments provided in this application, impeller 1 is a mixed-flow impeller.

[0041] In this embodiment, a mixed-flow impeller is used as impeller 1, combining the advantages of both centrifugal and axial flow impellers. The fluid flows out in an inclined direction, which can achieve a higher head at a larger flow rate, improving pump efficiency; it also operates smoothly with low vibration, adapting to various working conditions and enhancing the performance stability and applicability of the shielded motor core pump.

[0042] like Figure 1 , Figure 3 and Figure 7 As shown, in some embodiments provided in this application, the guide vane 2 includes: a guide vane blade, a guide vane front cover plate 6 and a guide vane rear cover plate 7. The guide vane front cover plate 6 and the guide vane rear cover plate 7 are located on both sides of the guide vane blade. The guide vane blade includes N blades arranged circumferentially along the axis of rotation, where N satisfies: 7≤N≤11, and N is a positive integer.

[0043] In this embodiment, the number N of guide vanes 2 satisfies 7 ≤ N ≤ 11 and is a positive integer. Within this range, a suitable number of guide vanes 2 can effectively guide the flow direction of the fluid at the impeller 1 outlet, allowing the fluid to enter the pump casing 3 more smoothly, reducing hydraulic losses and improving pump efficiency. Simultaneously, it can rationally distribute fluid energy, reducing the impact of the fluid on the pump casing 3, and mitigating vibration and noise. Moreover, this number range ensures performance while considering the feasibility and cost of the manufacturing process, achieving a good balance between performance, reliability, and economy in the canned motor nuclear main pump.

[0044] In some embodiments provided in this application, the exit blade angle of the guide vane 2 includes the exit angle A of the guide vane front cover plate and the exit angle B of the guide vane rear cover plate, which satisfy the following relationship: 44°≤A≤46°, 44°≤B≤46°.

[0045] In this embodiment, in terms of hydraulic performance, this angle range allows the fluid at the outlet of guide vane 2 to achieve an ideal flow direction and velocity distribution. A suitable outlet angle can effectively guide the high-speed fluid thrown out by vane 2 and impeller 1, smoothly converting its kinetic energy into pressure energy, reducing energy loss, improving pump efficiency and head, and allowing the fluid to enter the pump casing 3 more smoothly.

[0046] From the perspective of structural stability, this angle design helps to balance the fluid forces on the front cover plate 6 and the rear cover plate 7 of the guide vane, reduce the risk of vibration and deformation of the guide vane 2 caused by uneven force, ensure that the overall strength and rigidity of the guide vane 2 meet the requirements of operating conditions, and extend its service life.

[0047] like Figure 11 , Figure 12 and Figure 13As shown, in some embodiments provided in this application, the guide vane outlet inclination angle γ satisfies the following relationship: -14°≤γ≤+9°; wherein, the guide vane outlet inclination angle γ is the angle between the line connecting the center of the trailing edge of the guide vane front cover plate 6 and the guide vane rear cover plate 7 and a straight line passing through the center of the trailing edge of the guide vane rear cover plate 7 and parallel to the axis of rotation.

[0048] In this embodiment, in terms of hydraulic performance, a suitable guide vane outlet inclination angle range can optimize the fluid flow path within the guide vane 2. When the inclination angle is between -14° and 9°, it can effectively guide the fluid with rotational kinetic energy at the outlet of the impeller 1 and the blade 2, causing it to flow in an ideal direction, reducing the impact of the fluid on the pump casing 3 and the backflow within the pump casing 3, reducing hydraulic losses, and thus improving pump efficiency and increasing performance parameters such as head. A negative angle indicates backward tilting of the blade, and a positive angle indicates forward tilting of the guide vane. The three cases—guide vane outlet inclination angle γ greater than 0, equal to 0, and less than 0—are respectively as follows: Figure 11 , Figure 12 and Figure 13 As shown.

[0049] From a structural stability perspective, this inclination angle range helps improve the flow uniformity of the fluid at the outlet of guide vane 2, reducing the alternating fluid forces caused by the interaction between the turbulent water flow and the pump casing. It avoids guide vane 2 being subjected to alternating stress for extended periods due to excessively large or small inclination angles, reducing vibration and deformation of guide vane 2, ensuring that the strength and rigidity of guide vane 2 meet operating requirements, and extending its service life.

[0050] like Figure 7 As shown, in some embodiments provided in this application, the difference between the wrap angle D of the guide vane rear cover plate and the wrap angle C of the guide vane front cover plate satisfies the following relationship: 9°≤DC≤11°.

[0051] In this embodiment, the difference range can optimize the flow characteristics of the fluid within the guide vane 2 in terms of hydraulic performance. A suitable wrap angle difference allows the fluid to obtain different guiding effects at the front cover plate 6 and the rear cover plate 7 of the guide vane, making the fluid flow more uniform and smooth within the guide vane 2 channel, reducing fluid separation and secondary flow phenomena, reducing hydraulic losses, and thus improving pump efficiency and head, and enhancing fluid delivery capacity.

[0052] From a structural stability perspective, this wrap angle difference helps balance the fluid forces acting on the guide vane's front cover plate 6 and rear cover plate 7. This avoids problems such as deformation and vibration of the guide vane 2 caused by excessive or uneven stress concentration, ensuring that the strength and rigidity of the guide vane 2 meet operational requirements and extending its service life.

[0053] like Figure 4 , Figure 5 and Figure 6As shown, in some embodiments provided in this application, the pump housing 3 includes a spherical body and a water outlet cylinder 8 protruding from the outer surface of the spherical body. The spherical body and the water outlet cylinder 8 are connected by a tapering structure from approximately rectangular to circular.

[0054] In this embodiment, the pump casing 3 adopts a design with a spherical body and a specific outlet cylinder 8. The spherical body has high structural strength, can evenly withstand the internal fluid pressure, reduce the risk of stress concentration, and improve the durability of the pump casing 3. The spherical body and the outlet cylinder 8 are connected by a gradually narrowing structure from an approximately rectangular shape to a circle, which can rectify the fluid, making the fluid flow more concentrated and stable when flowing out, reducing turbulence and energy loss, thereby improving the pump's outlet pressure and efficiency. At the same time, this structure can also reduce the impact force of the fluid on the outlet of the pump casing 3 to a certain extent, reduce vibration and noise, and ensure the stable and reliable operation of the shielded motor nuclear main pump.

[0055] The second aspect of this application proposes a shielded motor nuclear main pump, comprising: a shielded motor nuclear main pump hydraulic model as described in any of the above embodiments.

[0056] The shielded motor nuclear main pump provided in this application includes the hydraulic model of the shielded motor nuclear main pump in any of the above embodiments, and therefore has all the beneficial technical effects of the hydraulic model of the shielded motor nuclear main pump, which will not be repeated here.

[0057] like Figures 1 to 10 As shown in the specific embodiment, this application provides a hydraulic model of a shielded motor nuclear main pump. This hydraulic model of a shielded motor nuclear main pump is a high-power shielded motor nuclear main pump hydraulic model that is efficient and easy to manufacture under multiple constraints. It includes: an impeller 1 and matching radial guide vanes 2 and pump casing 3.

[0058] Impeller 1 consists of four blades. The blades of impeller 1 are three-dimensional linear structure blades 9 formed by the blade shape control on both sides of its front cover plate and rear cover plate. The blade shape wrap angle on the rear cover plate side is 29° larger than the wrap angle on the front cover plate side. Both wrap angles are relatively small, which has good machinability and can meet the overall milling process requirements of impeller 1. It can also meet the requirements of high efficiency, high stability and reliability of impeller 1.

[0059] The guide vane 2 consists of 7 to 11 blades. The blades of the guide vane 2 are three-dimensional structure blades 9 with linear elements formed by two cross sections on the front cover plate and the rear cover plate. The circumferential arrangement of the blades is adapted to the structure of the pump casing 3. This design helps the water flow from the guide vane 2 at the bottom of the pump casing 3 to flow smoothly directly out of the pump casing 3 along the water outlet cylinder. It effectively reduces the large-area backflow of water flow in the bottom right area of ​​the water outlet cylinder caused by the unreasonable circumferential arrangement of the guide vane 2 at the bottom of the water outlet cylinder and the flow loss caused by it.

[0060] The pump casing 3 consists of a spherical body and a water outlet cylinder 8. The structure of the water outlet cylinder 8 of the pump casing 3 has changed from a previous circular-to-circular tapering structure to an approximately rectangular-to-circular tapering structure.

[0061] The specific improvements are as follows: First, to address the issue of integral milling of impeller 1 and reduce machining costs, the following improvements were made to impeller 1: The inlet blade angle of impeller 1 was optimized to adapt to the upstream flow; the blade angle distribution was improved, resulting in a reasonable load distribution that exhibits a standard normal distribution. The impeller 1 blades were changed from point-element three-dimensional structure blades 10 to line-element three-dimensional structure blades 9. The benefits of this method in the improved design of impeller 1 include reducing the number of intermediate cross-sections in the blade profile and simplifying the optimization and improvement design work of the impeller 1 blade profile.

[0062] Secondly, to achieve integral milling of impeller 1, the number of blades was reduced from 5 to 4. Furthermore, by decreasing the wrap angles of the front and rear shrouds and the difference between them, the wrap angle on the rear shroud side was made only 29° larger than that on the front shroud side, thus reducing the impeller 1's head and blade twist. Finally, the meridian and blade profile of impeller 1 were parametrically fitted using the Design3D module of NUMECA software, and targeted automatic optimization designs were performed on its meridian profile and blade profile, improving the efficiency of impeller 1 while meeting the requirements for head, flow rate, and net positive suction head (NPSH).

[0063] Guide vane 2 optimization: Using impeller 1, which has sufficient head margin and optimal efficiency, as the upstream element, and combining it with guide vane 2 for analysis, the inlet blade angle, meridional profile, and blade angle distribution of guide vane 2 were adjusted based on the analysis results to obtain the required channel area distribution, annular area distribution, and suitable pressure recovery coefficient. The blades of guide vane 2 were changed from point element three-dimensional blades (10) to line element three-dimensional structure blades (9). The number of blades in guide vane 2 was gradually reduced from the original 18 to 7-11. The meridional profile of guide vane 2 was changed from a Bezier curve to a combination of circular arcs and straight lines. The inclination angle distribution of guide vane 2 was gradually optimized from +10° to -47° to +9° to -14°. The outlet blade angle of guide vane 2 was increased by 13° compared to the original design. The wrap angle difference between the front and rear cover plates of guide vane 2 was reduced to approximately 10°. The minimum distance between the blades on the rear cover plate side was increased to 1.57 times that of the original design. These improvements to guide vane 2 not only improved hydraulic efficiency but also improved manufacturability.

[0064] like Figure 9 and Figure 10As shown, light gray represents the line element three-dimensional structure blade 9, and dark gray represents the point element three-dimensional structure blade 10. The purpose of changing the impeller 1 blade and guide vane 2 blades from point element three-dimensional blades 10 to line element three-dimensional structure blades 9 is twofold: firstly, to increase the machinability of the main pump impeller 1 and guide vane 2; milling can increase the precision of the internal flow channels and blade profiles of impeller 1 and guide vane 2, ensuring the performance of the main pump; secondly, compared to point element three-dimensional blades 10, line element three-dimensional structure blades 9 can significantly reduce processing costs.

[0065] The integrally milled impeller 1 and guide vane 2 are significantly superior to the cast impeller 1 in terms of material utilization, processing efficiency, processing quality, and the absence of casting defects. Therefore, the hydraulic model of the shielded motor nuclear main pump provided in this application optimizes the meridional profile and blade angle distribution while meeting hydraulic performance requirements, resulting in better machinability of the impeller 1 and guide vane 2, facilitating milling and reducing processing costs.

[0066] In terms of design methodology, the traditional method for designing a hydraulic model of a shielded motor nuclear main pump involves preliminary design and development of the entire pump model based on parameters such as flow rate, head, efficiency, and speed. This is followed by analysis and optimization using commercial CFD software. Based on the results of numerical analysis and experiments, and the discrepancies between the design and the required parameters, further design improvements are made. For example, if the head is insufficient, it can be increased by adjusting the impeller 1 outer diameter, blade outlet installation angle, and impeller 1 outlet width. If the efficiency is insufficient, the impeller 1 efficiency is improved first, followed by the matching design of impeller 1 and guide vane 2, and then the matching design of guide vane 2 and pump casing 3. The drawback of this method is that increasing the efficiency of impeller 1, guide vane 2, and pump casing 3 during the research process increases the overall pump head, necessitating subsequent methods such as cutting the impeller 1 outer diameter, reducing the impeller 1 outlet width, and decreasing the impeller 1 outlet installation angle to reduce the overall pump head. This results in numerous back-and-forth processes, low efficiency, and slow progress in the entire development process. The hydraulic model development method of this patent adopts the order of progressively deducing the respective loss indicators from back to front, based on the optimization target: pump casing 3-guide vane 2-impeller 1. This reduces the back-and-forth of the R&D process, improves R&D efficiency, and accelerates the R&D progress.

[0067] Regarding manufacturing process, the existing impeller 1 and guide vane 2 have a large number of blades, which are three-dimensional point element blades. Both impeller 1 and guide vane 2 are manufactured using casting methods, resulting in numerous casting defects. In particular, casting defects in the area of ​​significant alternating stress variation at the leading edge of the impeller 1 blades can easily lead to blade fatigue failure even after repair, failing to guarantee the design requirement of a 60-year lifespan for the main pump.

[0068] Furthermore, the internal flow channel of the existing point element impeller 1 is difficult to machine and the machining cost is very high, and it is impossible to complete the machining using the integral milling method. The existing guide vane 2 also has problems with poor machinability, such as a large number of blades, a large blade wrap angle, a narrow channel between blades, and an excessively large blade inclination angle.

[0069] The hydraulic model of the shielded motor nuclear main pump provided in this application features an impeller 1 and guide vane 2 integrally machined from forgings. The design incorporates fewer blades, smaller wrap angles, smaller inclination angles, and wider channels. Compared to castings, forging improves the microstructure and mechanical properties of the metal. After hot working deformation via forging, the original coarse dendrites and columnar grains transform into finer, more uniform equiaxed recrystallized grains due to metal deformation and recrystallization. This compacts and welds away existing segregation, porosity, pores, and inclusions within the ingot, resulting in a denser microstructure and improved plasticity and mechanical properties. The mechanical properties of castings are lower than those of forgings of the same material. Forging ensures the continuity of the metal fibrous structure, maintaining consistency between the fibrous structure and the shape of the forging, resulting in complete metal flow lines and guaranteeing good mechanical properties and a long service life for the impeller 1 and guide vane 2. During the forging process, a very fine granular structure is formed, further improving the physical properties of the metal. In practical use, if impeller 1 and guide vane 2 are designed properly, the particle flow can be directed in the direction of the main pressure. Compared to casting, milling can more accurately ensure that the profile of the hydraulic model meets the requirements.

[0070] In this application, the term "multiple" refers to two or more unless otherwise expressly defined. The terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "linking" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0071] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0072] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A hydraulic model for a shielded motor-driven nuclear main pump, characterized in that, include: An impeller is used to mount the shaft of a shielded motor nuclear main pump. The blades of the impeller are three-dimensional blades with linear elements. Guide vanes, which cooperate with the impeller, have blades that are three-dimensional linear element structures. Pump casing, which mates with the guide vanes; The shape of the three-dimensional structure blade of the line element is determined by two sets of curve elements located on the front cover plate and the rear cover plate. The curve elements include the leading edge line, trailing edge line, pressure surface line and suction surface line, which are described by the meridional curve, the mid-arc angle distribution and the thickness distribution. Based on the parameterized meridional curve, the mid-arc angle distribution and the thickness distribution, the leading edge line, trailing edge line, pressure surface line and suction surface line of the front cover plate and the rear cover plate are generated, and the continuous surface is constructed by lofting, sweeping or meshing.

2. The hydraulic model of the shielded motor-driven main pump according to claim 1, characterized in that, The impeller includes: impeller blades, an impeller front cover plate, and an impeller rear cover plate. The impeller front cover plate and the impeller rear cover plate are located on both sides of the impeller blades. The impeller blades include four blades spaced circumferentially along the axis of rotation.

3. The hydraulic model of the shielded motor-driven main pump according to claim 2, characterized in that, The blade wrap angle α on the rear cover plate side and the blade wrap angle β on the front cover plate side of each impeller blade satisfy the following relationship: 28°≤α-β≤30°; Wherein, α is the angle between the leading and trailing edges of the profile at the rear cover plate and the impeller shaft center on the axial projection, and β is the angle between the leading and trailing edges of the profile at the front cover plate and the impeller shaft center on the axial projection.

4. The hydraulic model of the shielded motor-driven main pump according to claim 1, characterized in that, The impeller is a mixed-flow impeller.

5. The hydraulic model of the shielded motor-driven nuclear main pump according to claim 1, characterized in that, The guide vane includes: a guide vane blade, a guide vane front cover plate, and a guide vane rear cover plate. The guide vane front cover plate and the guide vane rear cover plate are located on both sides of the guide vane blade. The guide vane blade includes N blades arranged circumferentially along the axis of rotation, where N satisfies: 7≤N≤11, and N is a positive integer.

6. The hydraulic model of the shielded motor-driven nuclear main pump according to claim 5, characterized in that, The exit blade angle of the guide vane includes the exit angle A of the guide vane front cover plate and the exit angle B of the guide vane rear cover plate, which satisfy the following relationship: 44°≤A≤46°, 44°≤B≤46°.

7. The hydraulic model of the shielded motor-driven nuclear main pump according to claim 5, characterized in that, The guide vane outlet inclination angle γ satisfies the following relationship: -14°≤γ≤+9°; Wherein, the guide vane outlet inclination angle γ is the angle between the line connecting the centers of the trailing edges of the guide vane front cover plate and the guide vane rear cover plate, and a straight line passing through the center of the trailing edge of the guide vane rear cover plate and parallel to the axis of the rotating shaft.

8. The hydraulic model of the shielded motor-driven main pump according to claim 5, characterized in that, The difference between the wrap angle D of the guide vane rear cover plate and the wrap angle C of the guide vane front cover plate satisfies the following relationship: 9°≤DC≤11°.

9. The hydraulic model of the shielded motor-driven nuclear main pump according to claim 1, characterized in that, The pump casing includes a spherical body and a water outlet cylinder protruding from the outer surface of the spherical body. The spherical body and the water outlet cylinder are connected by a gradually tapering structure from approximately rectangular to circular.

10. A shielded motor-driven nuclear main pump, characterized in that, include: The hydraulic model of the shielded motor nuclear main pump as described in any one of claims 1 to 9.

Images