Novel variant design method and system for dynamic adjusting axial flow fan of power station

Abstract

The invention discloses a novel variant design method and system for a dynamic adjusting axial flow fan of a power station, and the method comprises the steps: selecting a fan variant design scheme according to fan technical parameters before and after the energy-saving transformation of the dynamic adjusting axial flow fan; according to the fan variant design scheme, a specific fan variant design method is given; and according to the determined fan variant design scheme and the fan variant design method, dynamic regulation fan variant design transformation is implemented. The system comprises a design scheme selection module, a design method determination module and a design transformation implementation module. The method overcomes the problems of high investment cost, long reconstruction period, general reconstruction effect and the like of a traditional reconstruction scheme, and is suitable for being popularized and applied to various types of thermal power generating units throughout the country.

Description

Technical Field

[0001] The present invention belongs to the technical field of dynamically adjustable axial flow fans for power stations, and in particular relates to a novel variant design method and system for dynamically adjustable axial flow fans for power stations. Background Art

[0002] A dynamically adjustable axial flow fan, also known as an adjustable-blade axial flow fan, is a special type of axial flow fan. Its blades can be adjusted to vary the air volume and pressure. They are named for the axial direction of fluid flow, resulting in high flow rates and low pressure. Their operating principle is based on Newton's third law of action and reaction. When the motor drives the impeller to rotate, the blades draw air in from the air inlet and, propelled by the blades, expel the air axially. By adjusting the blade angle, the fan's flow rate and pressure can be varied.

[0003] Currently, dynamically adjustable axial flow fans are widely used in various types of thermal power units across China. As thermal power units face the need for flexible peak-shaving operations, problems such as low operating opening, high operating energy consumption, and poor regulation capability are becoming increasingly prominent. To improve the applicability of dynamically adjustable axial flow fans during low-load operation, it is necessary to technically upgrade and renovate these fans. Traditional renovation solutions often involve replacing the entire fan, which not only incurs significant investment costs and a long payback period, but also struggles to achieve optimal compatibility between the fan and the system due to the limited number of blade profiles available from fan manufacturers.

[0004] Based on the above problems, it is necessary to propose a new method for the transformation of power station dynamic adjustment axial flow fans. By simply modifying the design of the part of the dynamic adjustment axial flow fan body, it is possible to achieve multiple goals such as saving investment costs, shortening the investment recovery period, achieving deep energy saving of the fan, and ensuring the safe and reliable operation of the fan. Summary of the Invention

[0005] The present invention proposes a novel modified design method and system for a power plant's dynamically adjustable axial flow fan. This method, by modifying the impeller section of the fan's main body, only modifies the fan's impeller section casing and moving blades, while reusing the rest of the fan body. This achieves the dual goals of improving the fan's blade adjustment characteristics and simultaneously enhancing the fan's operating economy. The present invention proposes a new energy-saving modification technology for power plant dynamically adjustable axial flow fans, overcoming the high investment costs, long modification periods, and mediocre modification results of traditional modification schemes. The method is suitable for promotion and application in various types of thermal power units nationwide.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a novel variant design method for a power station dynamically adjustable axial flow fan, comprising: Select the fan variant design scheme based on the technical parameters of the fan before and after the energy-saving transformation of the dynamic axial flow fan; According to the fan variant design scheme, the specific fan variant design method is given; According to the determined fan variant design scheme and fan variant design method, the dynamic adjustment fan variant design transformation is implemented.

[0007] A further improvement of the present invention is to select a fan variant design scheme based on the technical parameters of the fan before and after the energy-saving transformation of the dynamically adjustable axial flow fan, including: Wind turbine blade height Adjustment: Shorten the height of the wind turbine blades after transformation , so that it satisfies , where The height of the blades before the fan is modified. is the blade height after fan modification, in mm. is the flow coefficient corresponding to the TB point selection parameters of the fan before transformation, The flow coefficient corresponding to the TB point selection parameters of the modified fan; Fan casing inner diameter Adjustment: After shortening the fan casing, the inner diameter is , and satisfy: , where The inner diameter of the fan casing before modification, The inner diameter of the fan casing after modification, in mm. At the same time, the fan blade tip clearance before and after modification Remain unchanged.

[0008] A further improvement of the present invention is that the fan variant design is divided into a variant design of the moving blades and a variant design of the inner cylinder of the impeller section casing.

[0009] A further improvement of the present invention is that the modified design of the dynamic adjustment axial flow fan blades includes: The height of the wind turbine blades is determined by Shorten to , using the blade annular cutting method, the moving blade The blades at and below the height remain unchanged. to Part of the blade height is cut in an annular shape. The center of the cutting ring is located at the center line of the fan rotation. The radius of curvature of the ring is , and satisfy: ; The blisk and blade root rounding structure of the wind turbine blade remain unchanged, wherein the blisk includes bolt holes, thus completing the modified design of the dynamic axial flow wind turbine blade.

[0010] A further improvement of the present invention is that the modified design of the inner cylinder of the casing of the dynamic axial flow fan impeller section includes: The impeller section casing inner cylinder is composed of three parts: the front conical cylinder, the cylindrical inner cylinder and the rear conical cylinder, which together form the structure of the impeller section casing inner cylinder; The front cone is a conical cylinder with a front cone angle of , and satisfy: ; The cylinder is a cylindrical cylinder. The radius of curvature of the cylindrical curve inside the cylinder is ; The rear cone is a conical cylinder with a rear cone angle of , and satisfy: .

[0011] A further improvement of the present invention is that the front conical cylinder, the cylindrical cylinder and the rear conical cylinder are connected to the impeller section casing and to each other by welding, and the welding adopts a full welding method, and the weld height is more than 3 mm.

[0012] The present invention also provides a novel variant design system for a power station dynamically adjustable axial flow fan, comprising: The design scheme selection module is used to select fan variant design schemes based on the technical parameters of the fan before and after the energy-saving transformation of the dynamic axial flow fan; The design method determination module is used to provide a specific fan variant design method based on the fan variant design scheme; The design and transformation implementation module is used to implement the dynamic adjustment fan variant design and transformation according to the determined fan variant design scheme and fan variant design method.

[0013] A further improvement of the present invention is that, in the design scheme selection module, a fan variant design scheme is selected based on the technical parameters of the fan before and after the energy-saving transformation of the dynamically adjustable axial flow fan, including: Wind turbine blade height Adjustment: Shorten the height of the wind turbine blades after transformation , so that it satisfies , where The height of the blades before the fan is modified. is the blade height after fan modification, in mm. is the flow coefficient corresponding to the TB point selection parameters of the fan before transformation, The flow coefficient corresponding to the TB point selection parameters of the modified fan; Fan casing inner diameter Adjustment: After shortening the fan casing, the inner diameter is , and satisfy: , where The inner diameter of the fan casing before modification, The inner diameter of the fan casing after modification, in mm. At the same time, the fan blade tip clearance before and after modification Remain unchanged.

[0014] A further improvement of the present invention is that the fan variant design is divided into a variant design of the moving blades and a variant design of the inner cylinder of the impeller section casing.

[0015] A further improvement of the present invention is that the modified design of the dynamic adjustment axial flow fan blades includes: The height of the wind turbine blades is determined by Shorten to , using the blade annular cutting method, the moving blade The blades at and below the height remain unchanged. to Part of the blade height is cut in an annular shape. The center of the cutting ring is located at the center line of the fan rotation. The radius of curvature of the ring is , and satisfy: ; The blisk and blade root rounding structure of the wind turbine blade remain unchanged, wherein the blisk includes bolt holes, thus completing the modified design of the dynamic axial flow wind turbine blade.

[0016] Compared with the prior art, the present invention has at least the following beneficial technical effects: The present invention provides a novel variant design method and system for a dynamically adjustable axial flow fan in a power station. A fan variant design scheme is selected based on the technical parameters of the fan before and after the energy-saving transformation of the dynamically adjustable axial flow fan. Then, a specific fan variant design method is given based on the fan variant design scheme. Finally, the dynamically adjustable fan variant design transformation is implemented based on the fan variant design scheme and variant design method determined above.

[0017] This invention allows for the development of customized, customized, and modified designs for dynamically adjustable axial flow fans based on actual user needs. By modifying only the impeller section of the fan body (including the fan blades and impeller section housing), all other parts of the fan body can be reused, precisely reducing fan output and achieving deep energy savings. This also effectively improves fan regulation performance and expands the fan's operating range, resulting in significant energy-saving improvements. This invention proposes a novel energy-saving retrofit technology for dynamically adjustable axial flow fans in power plants, overcoming the challenges of traditional retrofit solutions, such as high investment costs, long renovation periods, and limited effectiveness. It offers a promising market for widespread application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 The present invention is a flow chart of a new variant design method for a dynamically adjustable axial flow fan in a power station.

[0020] Figure 2 This is a schematic diagram of the new variant design structure of the power station dynamically adjustable axial flow fan of the present invention.

[0021] Figure 3 This is a structural block diagram of a new variant design system for a dynamically adjustable axial flow fan in a power station according to the present invention.

[0022] Explanation of the accompanying symbols: 1. fan rotor blade, 2. fan impeller section casing inner cylinder, 21. front conical cylinder, 22. cylindrical cylinder, 23. rear conical cylinder.

[0023] in, is the flow coefficient corresponding to the TB point selection parameters of the fan before transformation, is the pressure coefficient corresponding to the TB point selection parameters of the fan before transformation, The flow coefficient corresponding to the TB point selection parameter of the modified fan is: It is the pressure coefficient corresponding to the TB point selection parameter of the modified fan.

[0024] The height of the moving blades before the fan is modified. is the height of the moving blades after the fan is modified, The inner diameter of the fan casing before modification, The inner diameter of the fan casing after modification. is the radius of curvature of the blade annular cutting, and the above units are all in mm.

[0025] is the front cone angle, is the back cone angle, and the above units are all in degrees. DETAILED DESCRIPTION

[0026] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0027] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0028] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0029] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0030] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0031] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0032] Example 1 like Figure 1 As shown, this embodiment provides a novel variant design method for a power station dynamically adjustable axial flow fan, including: Select the fan variant design scheme based on the technical parameters of the fan before and after the energy-saving transformation of the dynamic axial flow fan; According to the fan variant design scheme, the specific fan variant design method is given; According to the determined fan variant design scheme and fan variant design method, the dynamic adjustment fan variant design transformation is implemented.

[0033] In this embodiment, based on the technical parameters of the dynamically adjustable axial flow fan before and after the energy-saving transformation, a fan variant design scheme is selected, including: Wind turbine blade height Adjustment: Shorten the height of the wind turbine blades after transformation , so that it satisfies , where The height of the blades before the fan is modified. is the blade height after fan modification, in mm. is the flow coefficient corresponding to the TB point selection parameters of the fan before transformation, The flow coefficient corresponding to the TB point selection parameters of the modified fan; Fan casing inner diameter Adjustment: After shortening the fan casing, the inner diameter is , and satisfy: , where The inner diameter of the fan casing before modification, The inner diameter of the fan casing after modification, in mm. At the same time, the fan blade tip clearance before and after modification Remain unchanged.

[0034] In this embodiment, the fan variant design scheme is divided into a variant design of the moving blades 1 and a variant design of the impeller section casing inner cylinder 2.

[0035] Furthermore, the modified design of the dynamically adjustable axial flow fan blade 1 includes: The height of wind turbine blade 1 is Shorten to , using the blade annular cutting method, the moving blade 1 The blades at and below the height remain unchanged. to Part of the blade height is cut in an annular shape. The center of the cutting ring is located at the center line of the fan rotation. The radius of curvature of the ring is , and satisfy: ; The blade disk and the rounded structure of the blade root of the wind turbine blade 1 remain unchanged, wherein the blade disk includes bolt holes, thus completing the modified design of the dynamic axial flow wind turbine blade 1 .

[0036] Among them, the moving blades usually consist of a blade body, a connecting piece, and an adjusting mechanism. The blade body is the main part that generates aerodynamic force, the connecting piece is used to fix the blade to the hub, and the adjusting mechanism is used to adjust the inclination angle of the blade. The working principle of the moving blades of a dynamic axial flow fan is based on the principles of fluid mechanics and aerodynamics. When the fan is started, the motor drives the impeller to rotate, and the moving blades rotate accordingly and generate aerodynamic force. By adjusting the inclination angle of the blades, the propulsion effect of the blades on the gas can be changed, thereby changing the flow rate and wind pressure of the fan. Specifically, when the inclination angle of the blades increases, the propulsion effect of the blades on the gas increases, and the flow rate and wind pressure of the fan increase accordingly; conversely, when the inclination angle of the blades decreases, the propulsion effect of the blades on the gas weakens, and the flow rate and wind pressure of the fan decrease.

[0037] The modified design of the inner cylinder 2 of the casing of the dynamic axial flow fan impeller section includes: The impeller section casing inner cylinder 2 is composed of three parts: a front conical cylinder 21, a cylindrical inner cylinder 22 and a rear conical cylinder 23, which together constitute the structure of the impeller section casing inner cylinder 2; The front cone 21 is a conical cylinder with a front cone angle of , and satisfy: ; The cylinder 22 is a cylindrical cylinder, and the curvature radius of the cylindrical curve inside the cylinder is ; The rear cone 23 is a cone-shaped cylinder with a rear cone angle of , and satisfy: .

[0038] The tapered structures of the front and rear cones help guide the fluid smoothly into and out of the impeller section, ensuring efficient interaction between the fluid and the impeller. The inner cylindrical barrel provides a stable flow path for the fluid, reducing turbulence and resistance within the impeller section, thereby improving fluid stability and efficiency. The structure consisting of the front, inner, and rear cones not only offers advantages in fluid dynamics but also possesses excellent structural strength, capable of withstanding fluid pressure and mechanical loads.

[0039] Furthermore, the front conical cylinder 21, the cylindrical cylinder 22 and the rear conical cylinder 23 are connected to the impeller section casing and to each other by welding. The welding adopts a full welding method, and the weld height is more than 3 mm.

[0040] Example 2 like Figure 3 As shown, this embodiment provides a new variant design system for a power station dynamically adjustable axial flow fan, including: The design scheme selection module is used to select fan variant design schemes based on the technical parameters of the fan before and after the energy-saving transformation of the dynamic axial flow fan; The design method determination module is used to provide a specific fan variant design method based on the fan variant design scheme; The design and transformation implementation module is used to implement the dynamic adjustment fan variant design and transformation according to the determined fan variant design scheme and fan variant design method.

[0041] In this embodiment, in the design scheme selection module, a fan variant design scheme is selected based on the technical parameters of the fan before and after the energy-saving transformation of the dynamically adjustable axial flow fan, including: Wind turbine blade height Adjustment: Shorten the height of the wind turbine blades after transformation , so that it satisfies , where The height of the blades before the fan is modified. is the blade height after fan modification, in mm. is the flow coefficient corresponding to the TB point selection parameters of the fan before transformation, The flow coefficient corresponding to the TB point selection parameters of the modified fan; Fan casing inner diameter Adjustment: After shortening the fan casing, the inner diameter is , and satisfy: , where The inner diameter of the fan casing before modification, The inner diameter of the fan casing after modification, in mm. At the same time, the fan blade tip clearance before and after modification Remain unchanged.

[0042] In this embodiment, the fan variant design scheme is divided into a variant design of the moving blades 1 and a variant design of the impeller section casing inner cylinder 2.

[0043] Furthermore, the modified design of the dynamically adjustable axial flow fan blade 1 includes: The height of wind turbine blade 1 is Shorten to , using the blade annular cutting method, the moving blade 1 The blades at and below the height remain unchanged. to Part of the blade height is cut in an annular shape. The center of the cutting ring is located at the center line of the fan rotation. The radius of curvature of the ring is , and satisfy: ; The blade disk and the rounded structure of the blade root of the wind turbine blade 1 remain unchanged, wherein the blade disk includes bolt holes, thus completing the modified design of the dynamic axial flow wind turbine blade 1 .

[0044] Example 3 The fan of a 600MW unit in China is a single-stage axial flow fan with adjustable blades. The fan has 22 blades, an impeller diameter of 2660mm, and an inner diameter of the fan casing. mm, blade height mm, the rated speed of the motor is 990r / min, and the flow rate at point TB of the fan is 232m 3 / s, TB point pressure is 4730Pa, and intake air density is 1.183kg / m 3 After energy-saving transformation, the flow rate of fan TB point is 175 m 3 / s, TB point pressure is 3000Pa, and intake air density is 1.146kg / m 3 After calculation, the flow coefficient corresponding to the TB point selection parameters of the fan before transformation is obtained. , the pressure coefficient corresponding to the fan TB point selection parameters before transformation , after the transformation, the flow coefficient corresponding to the TB point selection parameters of the fan , the pressure coefficient corresponding to the TB point selection parameters of the fan after transformation Follow the steps below to implement the modified design of the dynamic axial flow fan: 1. Flow coefficient ratio before and after fan transformation ,satisfy Therefore, the modified design method of the dynamic axial flow fan of the present invention is adopted to implement the energy-saving transformation of the fan.

[0045] 2. Adjust the height of wind turbine blades. According to the method of the present invention, mm.

[0046] 3. Adjust the inner diameter of the fan casing. According to the method of the present invention, the inner diameter of the fan casing after the transformation is shortened. mm, fan blade tip clearance before and after transformation mm remains unchanged.

[0047] 4. According to the method of step 2 of the present invention, the modified design of the dynamic axial flow fan moving blade (1) and the impeller section casing inner cylinder (2) is completed.

[0048] 5. According to the method of step 3 of the present invention, implement the modified design of the dynamic axial flow fan.

[0049] After completing the above steps, the modified design and renovation of the dynamically adjustable axial flow fan was completed. After the modified design and renovation, the fan not only meets the output requirements of the newly selected operating point after the energy-saving renovation, but also reduces the fan's overall energy consumption by over 30%, increases the fan's blade angle adjustment range by over 20%, and significantly improves the fan's operating economy and equipment applicability. The energy-saving renovation of this fan has achieved remarkable results.

[0050] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all points of view, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and range of equivalents of the claims are included in the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0051] In addition, it should be understood that although this specification describes the embodiments, not every embodiment contains only one independent technical solution. This description is for clarity only. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for the purpose of illustrating the technical concept of the present invention and cannot be used to limit the scope of protection of the present invention. Any changes made based on the technical solution in accordance with the technical concept proposed by the present invention fall within the scope of protection of the claims of the present invention.

Claims

1. A new variant design method for a power station dynamically adjustable axial flow fan, characterized in that: include: Select a fan variant design scheme based on the technical parameters of the fan before and after the energy-saving transformation of the dynamic axial flow fan; According to the fan variant design scheme, the specific fan variant design method is given; According to the determined fan variant design scheme and fan variant design method, the dynamic adjustment fan variant design transformation is implemented.

2. A novel variant design method for a power station dynamically adjustable axial flow fan according to claim 1, characterized in that: Based on the technical parameters of the dynamic axial flow fan before and after energy-saving transformation, the fan variant design scheme is selected, including: Wind turbine blade height Adjustment: Shorten the height of the wind turbine blades after modification , so that it satisfies , where The height of the blades before the fan is modified. is the blade height after fan modification, in mm. is the flow coefficient corresponding to the TB point selection parameters of the fan before transformation, The flow coefficient corresponding to the TB point selection parameters of the modified fan; Fan casing inner diameter Adjustment: After shortening the fan casing, the inner diameter is , and satisfy: , where The inner diameter of the fan casing before modification, The inner diameter of the fan casing after modification, in mm. At the same time, the fan blade tip clearance before and after modification Remain unchanged.

3. A novel variant design method for a power station dynamically adjustable axial flow fan according to claim 2, characterized in that: The fan variant design scheme is divided into a variant design of the moving blades (1) and a variant design of the inner cylinder of the impeller section casing (2).

4. A novel variant design method for a power station dynamically adjustable axial flow fan according to claim 3, characterized in that: The variant design of the dynamic axial flow fan blade (1) includes: The height of the wind turbine blade (1) is determined by Shorten to , using the blade annular cutting method, the moving blade (1) The blades at and below the height remain unchanged. to Part of the blade height is cut in an annular shape. The center of the cutting ring is located at the center line of the fan rotation. The radius of curvature of the ring is , and satisfy: ; The blade disk and the rounded structure of the blade root of the wind turbine blade (1) remain unchanged, wherein the blade disk includes bolt holes, thus completing the modified design of the dynamically adjustable axial flow wind turbine blade (1).

5. A novel variant design method for a power station dynamically adjustable axial flow fan according to claim 3, characterized in that: The variant design of the inner cylinder (2) of the impeller section of the dynamic axial flow fan includes: The impeller section casing inner cylinder (2) is composed of three parts: a front conical cylinder (21), a cylindrical inner cylinder (22) and a rear conical cylinder (23), which together form the structure of the impeller section casing inner cylinder (2); The front cone (21) is a conical cylinder with a front cone angle of , and satisfy: ; The cylinder (22) is a cylindrical cylinder, and the curvature radius of the cylindrical curve inside the cylinder is ; The rear cone (23) is a conical cylinder with a rear cone angle of , and satisfy: .

6. A novel variant design method for a power station dynamically adjustable axial flow fan according to claim 5, characterized in that: The front conical cylinder (21), the cylindrical cylinder (22) and the rear conical cylinder (23) are connected to the impeller section casing and to each other by welding, and the welding adopts a full welding method, and the weld height is more than 3 mm.

7. A new variant design system for a power station dynamically adjustable axial flow fan, characterized in that: include: The design scheme selection module is used to select fan variant design schemes based on the technical parameters of the fan before and after the energy-saving transformation of the dynamic axial flow fan; The design method determination module is used to provide a specific fan variant design method based on the fan variant design scheme; The design and transformation implementation module is used to implement the dynamic adjustment fan variant design and transformation according to the determined fan variant design scheme and fan variant design method.

8. A novel variant design system for a power station dynamically adjustable axial flow fan according to claim 7, characterized in that: In the design scheme selection module, fan variant design schemes are selected based on the technical parameters of the dynamic axial flow fan before and after energy-saving transformation, including: Wind turbine blade height Adjustment: Shorten the height of the wind turbine blades after modification , so that it satisfies , where The height of the blades before the fan is modified. is the blade height after fan modification, in mm. is the flow coefficient corresponding to the TB point selection parameters of the fan before transformation, The flow coefficient corresponding to the TB point selection parameters of the modified fan; Fan casing inner diameter Adjustment: After shortening the fan casing, the inner diameter is , and satisfy: , where The inner diameter of the fan casing before modification, The inner diameter of the fan casing after modification, in mm. At the same time, the fan blade tip clearance before and after modification Remain unchanged.

9. A novel variant design system for a power station dynamically adjustable axial flow fan according to claim 8, characterized in that: The fan variant design scheme is divided into a variant design of the moving blades (1) and a variant design of the inner cylinder of the impeller section casing (2).

10. A novel variant design system for a power station dynamically adjustable axial flow fan according to claim 9, characterized in that: The variant design of the dynamic axial flow fan blade (1) includes: The height of the wind turbine blade (1) is determined by Shorten to , using the blade annular cutting method, the moving blade (1) The blades at and below the height remain unchanged. to Part of the blade height is cut in an annular shape. The center of the cutting ring is located at the center line of the fan rotation. The radius of curvature of the ring is , and satisfy: ; The blade disk and the rounded structure of the blade root of the wind turbine blade (1) remain unchanged, wherein the blade disk includes bolt holes, thus completing the modified design of the dynamically adjustable axial flow wind turbine blade (1).

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