A nuclear power centrifugal fan impeller with splitter blades

Abstract

This utility model discloses a nuclear power centrifugal fan impeller with splitting blades, comprising a front plate, main blades, a first splitting blade, a second splitting blade, and a rear plate forming an integral structure; a circular through hole is provided at the center of the rear plate for the installation and positioning of the drive shaft; the main blades are evenly arranged on the inner surface of the rear plate along the circumference of the impeller, and the first splitting blade and the second splitting blade are arranged sequentially between adjacent main blades, arranged in the following order along the impeller rotation direction (counterclockwise): main blade, first splitting blade, second splitting blade; the front plate and the rear plate are separated by the first splitting blade, the second splitting blade, and the main blade to form an internal flow channel; this utility model reduces airflow impact and eddy current loss, improves aerodynamic efficiency, effectively suppresses pressure pulsation, and reduces noise through the optimized structure of the backward-inclined inlet and splitting blades, solving the problems of low efficiency, unstable flow field, and high noise in nuclear power centrifugal fans, and meeting the special environmental requirements of nuclear islands.

Description

Technical Field

[0001] This utility model belongs to the technical field of centrifugal fan equipment, and relates to a nuclear power centrifugal fan impeller with diverter blades. Background Technology

[0002] Centrifugal fans are widely used in aviation, home appliances, energy, and other fields due to their simple structure and stable and reliable operation, playing an irreplaceable role, especially in the ventilation systems of nuclear power plants. As the power source component of the ventilation system, the centrifugal fan impeller has a significant impact on gas flow control, temperature regulation, and overall environmental safety. However, the complex internal flow field of the centrifugal impeller involves various flow phenomena such as three-dimensional unsteady flow, boundary layer separation, and secondary flow. Furthermore, its performance is affected by numerous geometric parameters, which are strongly coupled with each other, making impeller design challenging. The key to improving impeller aerodynamic efficiency lies in effectively suppressing pressure pulsations in the flow field and reducing flow losses, thereby achieving efficient and stable operation.

[0003] Currently, centrifugal fans used in nuclear power plant nuclear islands mostly employ all-blade impellers. Their designs typically follow established aerodynamic models from traditional fan design manuals, failing to fully incorporate the latest advancements in aerodynamic research. While this design meets the basic functional requirements of the nuclear island ventilation system for airflow and pressure, there is still significant room for improvement in aerodynamic efficiency. In actual operation, these impellers often exhibit high shaft power and low energy utilization, impacting the overall economic efficiency of the fan. Furthermore, under the current mainstream blade structure design, the flow state within the impeller channel is not uniform, particularly in the impeller outlet region, where unstable flow phenomena easily occur, leading to significantly enhanced pressure pulsation. This unstable flow characteristic not only generates substantial operating noise but may also induce vibration, further affecting the fan's operational stability and service life.

[0004] Composite impeller structures employing split-flow blades can improve flow field distribution to some extent, making them particularly suitable for low-flow-rate, high-pressure-ratio operating conditions. However, under the low-pressure-ratio, high-flow-rate conditions commonly used in nuclear power plants, existing structures still suffer from problems such as excessively low blade consistency, unreasonable axial positioning of the split-flow blades, and improper radial length settings. These issues prevent them from effectively guiding the main flow field and instead easily cause secondary flow and wake losses, exacerbating pressure pulsation and ultimately affecting fan efficiency and noise performance. Furthermore, centrifugal fans used in nuclear power plant nuclear islands must meet a series of special requirements, including radiation resistance, vibration resistance, wear resistance, and long service life. This places higher demands on the selection of impeller materials and structural design.

[0005] Therefore, in order to meet the actual needs of nuclear power plants for efficient, low-noise, safe and long-life ventilation systems, it is urgent to propose a new centrifugal fan impeller structure to overcome the shortcomings of existing technologies and improve its comprehensive performance and engineering applicability. Summary of the Invention

[0006] To achieve the above objectives, this utility model provides a nuclear power centrifugal fan impeller with flow divider blades, which solves the problems of low structural efficiency, unstable flow field, and high noise in the prior art, and meets the special environmental requirements of nuclear power plant nuclear island.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is: a nuclear power centrifugal fan impeller with splitting blades, comprising a front disc, main blades, a first splitting blade, a second splitting blade, and a rear disc forming an integral structure.

[0008] The rear disc has a circular through hole at its shaft center for mounting and positioning the drive shaft; the main blades are evenly arranged on the inner surface of the rear disc along the circumference of the impeller, and a first diversion blade and a second diversion blade are arranged sequentially between adjacent main blades, arranged in the following order along the impeller rotation direction (counterclockwise): main blade, first diversion blade, second diversion blade; the front disc and the rear disc are separated into an internal flow channel by the first diversion blade, the second diversion blade, and the main blade.

[0009] Furthermore, the leading edges of the main blade, the first split blade, and the second split blade all adopt variable diameter fillets with a fillet diameter of 2mm-4mm, and the trailing edges are all cut perpendicularly along the radial direction of the impeller and aligned with the outer diameter of the impeller.

[0010] Furthermore, the total number of the main blade, the first splitter blade, and the second splitter blade is Z. At the impeller outlet section, the circumferential angle between the main blade and its adjacent first and second splitter blades is [missing information]. Spend.

[0011] Furthermore, the starting positions of the first and second diverter blades are 70% of the radial length of the main blade; the outlet diameters of the first and second diverter blades are the same as those of the main blade, both being 506 mm, while the inlet diameter of the main blade is 137.6 mm. The inlet diameters of the first and second diverter blades are 0.93 times the outlet diameter of the main blade.

[0012] Furthermore, the inlet back tilt angle of the main blade is 42 degrees, and the inlet back tilt angle of the first and second split blades is 35 degrees.

[0013] Furthermore, the main blade has a uniform thickness of 3mm, and the first and second diversion blades have the same thickness as the main blade.

[0014] The beneficial effects of this utility model are:

[0015] 1. This invention, by designing the blade inlet to be backward-sloping when the fluid enters the impeller, gradually increases the size of the fan channel, effectively reducing impact losses at the airflow inlet. Furthermore, the use of diverting blades to constrain the flow direction not only suppresses fluid diffusion to a certain extent but also significantly reduces the possibility of vortex formation at the impeller outlet, thereby reducing flow losses. These design optimizations work together to improve the impeller's aerodynamic efficiency from 77.8% to 80.8%.

[0016] 2. In the process of fluid passing through the impeller channel, the probability of pressure pulsation is effectively reduced due to the more stable flow state, thereby significantly reducing the fluid noise generated during the operation of the fan. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, 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 utility model. 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 impeller structure of this utility model.

[0019] Figure 2 This is a schematic diagram of the wheel structure of this utility model.

[0020] In the diagram, 1. Front disc, 2. Main blade, 3. First splitter blade, 4. Second splitter blade, 5. Rear disc. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0022] This utility model provides an impeller for a nuclear power centrifugal fan with flow-diverting blades, the structure of which is as follows: Figure 1-2As shown, the impeller includes a front disc 1, main blades 2, first splitter blades 3, second splitter blades 4, and a rear disc 5. A circular through-hole is provided at the center of the rear disc 5 for mounting and positioning the drive shaft. The main blades 2 are evenly arranged on the inner surface of the rear disc 5 along the circumference of the impeller. A first splitter blade 3 and a second splitter blade 4 are sequentially arranged between adjacent main blades 2, arranged in the following order along the impeller rotation direction (counterclockwise): main blade 2, first splitter blade 3, second splitter blade 4. An internal flow channel is created between the front disc 1 and the rear disc 5 through the first splitter blade 3, second splitter blade 4, and main blades 2. Both the front disc 1 and the rear disc 5 are formed by stamping, while the main blades 2, first splitter blades 3, and second splitter blades 4 are formed by casting. The front disc 1, main blades 2, first splitter blades 3, second splitter blades 4, and rear disc 5 are welded together to form a closed impeller.

[0023] Furthermore, the leading edges of the main blade 2, the first split blade 3, and the second split blade 4 all adopt variable diameter fillets with a fillet diameter of 2mm-4mm, and the trailing edges are all cut perpendicularly along the radial direction of the impeller and aligned with the outer diameter of the impeller.

[0024] Furthermore, the total number of main blade 2, first splitter blade 3, and second splitter blade 4 is Z. At the impeller outlet section, the circumferential angle between the main blade 2 and its adjacent first splitter blade 3 and second splitter blade 4 is [missing information]. Spend.

[0025] Furthermore, the starting positions of the first splitter blade 3 and the second splitter blade 4 are 70% of the radial length of the main blade 2; the outlet diameters of the first splitter blade 3 and the second splitter blade 4 are the same as those of the main blade 2, both being 506 mm; the inlet diameter of the main blade 2 is 137.6 mm; and the inlet diameters of the first splitter blade 3 and the second splitter blade 4 are 0.93 times the outlet diameter of the main blade 2.

[0026] Furthermore, the inlet back tilt angle of the main blade 2 is 42 degrees, and the inlet back tilt angle of the first split blade 3 and the second split blade 4 is 35 degrees.

[0027] Furthermore, the main blade 2 has a uniform thickness of 3mm, and the first splitter blade 3 and the second splitter blade 4 have the same thickness as the main blade 2.

[0028] This invention employs a composite splitter blade structure and optimizes the axial arrangement of the first splitter blade 3 and the second splitter blade 4. The initial position of the first splitter blade 3 and the second splitter blade 4 is 70% of the radial length of the main blade 2, avoiding premature interference with the mainstream flow and providing good guidance in the later stages of flow, thus helping to suppress boundary layer separation and secondary flow generation. Regarding blade angle design, a differentiated inlet backslope angle strategy is adopted. The inlet backslope angle of the main blade 2 is 42 degrees to enhance inlet guidance capacity and reduce airflow impact loss. The inlet backslope angles of the first splitter blade 3 and the second splitter blade 4 are 35 degrees, balancing flow control and drag characteristics to avoid excessive compression of the mainstream flow. Simultaneously, the diameter ratio of the first splitter blade 3 and the second splitter blade 4 is optimized, making the inlet diameter of the first splitter blade 3 and the second splitter blade 4 approximately 0.93 times the outlet diameter of the main blade 2. This achieves a smooth transition between the flow fields of the first splitter blade 3 and the second splitter blade 4 and the outlet flow field of the main blade 2, reducing wake loss.

[0029] The working mechanism of this invention is as follows: The first splitter blade 3 and the second splitter blade 4 divide the main flow into multiple sub-flows, reducing the velocity gradient within the impeller channel, decreasing turbulent kinetic energy dissipation, and improving flow field uniformity; simultaneously, they constrain the fluid diffusion trend and suppress the formation of secondary vortices at the impeller outlet. Experimental data shows that the pressure pulsation amplitude is reduced by 15% (compared to a design without splitter blades). The backward tilting design at the blade inlet reduces intake impact losses, and the optimized streamline distribution of the splitter blades makes the airflow expansion smoother, reducing flow separation, and increasing the impeller aerodynamic efficiency from 77.8% to 80.8% (compared to a design without splitter blades).

[0030] The comparative test results of this utility model and the design without a splitter blade are as follows: In terms of aerodynamic performance, the efficiency under rated operating conditions is increased by 3 percentage points (77.8%→80.8%), and the shaft power is reduced by 8%; in terms of noise characteristics, according to the ISO 3744 standard test, the sound pressure level at 1 meter is reduced by 7 dB(A) (85→78), and the pressure pulsation amplitude is significantly reduced; in terms of flow field characteristics, CFD simulation shows that the splitter blade improves the uniformity of the outlet velocity distribution by 30% and reduces the intensity of the secondary flow by 40%.

[0031] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0032] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model are included within the scope of protection of this utility model.

Claims

1. A nuclear power centrifugal fan impeller with splitting blades, comprising a front disc (1), main blades (2), a first splitting blade (3), a second splitting blade (4), and a rear disc (5) forming an integral structure; characterized in that: The rear disc (5) has a circular through hole at its shaft center for the installation and positioning of the drive shaft; the main blades (2) are evenly arranged on the inner surface of the rear disc (5) along the circumference of the impeller, and the first diversion blade (3) and the second diversion blade (4) are arranged sequentially between adjacent main blades (2), and are arranged sequentially along the impeller rotation direction as: main blade (2), first diversion blade (3), second diversion blade (4); the front disc (1) and the rear disc (5) are separated into an internal flow channel by the first diversion blade (3), the second diversion blade (4), and the main blades (2).

2. A nuclear centrifugal fan impeller with splitter blades according to claim 1, characterized in that, The leading edges of the main blade (2), the first split blade (3), and the second split blade (4) all adopt variable diameter rounded corners with a rounded corner diameter of 2mm-4mm, and the trailing edges are all cut vertically along the radial direction of the impeller and aligned with the outer diameter of the impeller.

3. A nuclear centrifugal fan impeller with splitter blades according to claim 1, characterized in that, The total number of the main blades (2), the first splitter blades (3) and the second splitter blades (4) is Z, and the circumferential included angle between the main blade (2) and the first splitter blade (3) and the second splitter blade (4) adjacent to both sides of the main blade (2) at the outlet section of the impeller is degrees.

4. A nuclear centrifugal fan impeller with splitter blades according to claim 2, characterized in that, The starting positions of the first splitter blade (3) and the second splitter blade (4) are 70% of the radial length of the main blade (2); the outlet diameters of the first splitter blade (3) and the second splitter blade (4) are the same as those of the main blade (2), both being 506 mm; the inlet diameter of the main blade (2) is 137.6 mm; and the inlet diameters of the first splitter blade (3) and the second splitter blade (4) are 0.93 times the outlet diameter of the main blade (2).

5. A nuclear centrifugal fan impeller with splitter blades as claimed in claim 3, characterized in that, The main blade (2) has an inlet back tilt angle of 42 degrees, and the first split blade (3) and the second split blade (4) have an inlet back tilt angle of 35 degrees.

6. A nuclear power centrifugal fan impeller with splitter blades according to any one of claims 1-5, characterized in that, The thickness of the main blade (2), the first diverter blade (3), and the second diverter blade (4) is 3 mm.

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