Two-stage inducer wheel structure with bubble suppression effect and design method thereof

Abstract

The application discloses a two-stage inducer wheel structure with steam bubble suppression and a design method thereof, which comprises a main body, first-stage inducer wheel blades and second-stage inducer wheel blades arranged in sequence along the axial direction of the main body, a circulating channel formed in the main body, a steam bubble inlet formed in the tail end of the main body and communicated with the circulating channel, a steam bubble outlet formed in the head end of the main body and communicated with the circulating channel, and a steam bubble breaking structure arranged in the circulating channel. In actual use, the steam bubbles generated by the first-stage inducer wheel blades can be recycled in real time, introduced into the circulating channel in the interior through the second-stage inducer wheel blades, and largely eliminated in the circulating channel, so that the number of steam bubbles entering the main impeller is greatly reduced, and the performance of the main impeller and the performance of the unit are well ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of inducer, in particular to a two-stage inducer structure with bubble suppression effect and a design method thereof. BACKGROUND

[0002] An inducer is a device for improving the suction performance of a pump, usually installed in front of the first-stage impeller of a centrifugal pump. The liquid entering the pump is pre-processed to improve the working condition of the pump. In terms of structure, it is similar to a small axial-flow impeller with a hub and a number of twisted blades. The inducer is widely used in high-speed pumps and low net positive suction head (NPSH) applications. Since its own head significantly increases the inlet pressure of the main impeller, it realizes stable output of pump performance under the conditions of large flow, low NPSH and high speed.

[0003] However, in reality, the inducer often operates under a certain degree of cavitation, which produces more bubbles on the back of its inlet blades. Some of the bubbles will collapse before entering the main impeller due to the increase in pressure, and some of the bubbles will enter the downstream main impeller flow passage and collapse in the middle and downstream of the flow passage, causing great damage to the fluid conveying performance and structure, affecting the service life of the unit. SUMMARY

[0004] In order to better protect the performance of the main impeller and the performance of the unit, the present application provides a two-stage inducer structure with bubble suppression effect.

[0005] The present application provides a two-stage inducer structure with bubble suppression effect, which adopts the following technical scheme:

[0006] A two-stage inducer structure with bubble suppression effect, comprising a main body, the main body is sequentially provided with a first-stage inducer blade and a second-stage inducer blade along its axial direction, a circulating channel is formed in the main body, a bubble inlet is formed in the end of the main body and communicates with the circulating channel, a bubble outlet is formed in the front end of the main body and communicates with the circulating channel, and a bubble breaking structure is arranged in the circulating channel.

[0007] Optionally, the second-stage inducer blade is smaller than the first-stage inducer blade.

[0008] Optionally, the first-stage inducer blade and the second-stage inducer blade are both spiral blades, and the first-stage inducer blade and the second-stage inducer blade are both distributed with at least two pieces around the circumference.

[0009] Optionally, the leading edge wrap angle of the first-stage inducer blade is 60°-120°, the shroud wrap angle is 150°-350°, the inlet setting angle is 8°-18°, and the outlet setting angle is 25°-70°.

[0010] Optionally, the front end setting angle of the secondary inducer blade is greater than the rear end setting angle, the inlet setting angle of the secondary inducer blade is 30-60°, the outlet setting angle is 15-30°, and the wrap angle is 150-180°.

[0011] Optionally, the secondary inducer blade starts from the middle position of the outlet flow channel of the primary inducer blade, the steam bubble inlet is located at the outlet flow channel of the secondary inducer blade, the center line of the steam bubble inlet is close to the extension direction of the outlet flow channel of the secondary inducer, and a spiral cut-in structure is formed.

[0012] Optionally, the steam bubble breaking structure comprises a primary grid structure and a secondary grid structure, and the blockage coefficient of the primary grid structure is less than that of the secondary grid structure.

[0013] Optionally, the steam bubble inlet and the steam bubble outlet are uniformly distributed in multiple around the circumference of the main body, the diameter of the steam bubble inlet is greater than that of the steam bubble outlet, the steam bubble outlet is radially opened on the main body, and the steam bubble inlet is obliquely opened on the main body.

[0014] Optionally, the circulation channel is a reducing channel, the diameter of the circulation channel gradually decreases from one end close to the steam bubble inlet to the other end, and the flow rate of the circulation channel is 3-5% of the total flow rate of the pump.

[0015] The application also provides a design method of a two-stage inducer structure with steam bubble suppression effect, which adopts the following technical scheme:

[0016] A design method of a two-stage inducer structure with steam bubble suppression effect, comprising the following steps:

[0017] S1, determining the design target and determining the basic parameters of the pump;

[0018] S2, calculating and determining the basic parameters of the conventional inducer according to the basic parameters of the pump;

[0019] S3, designing the primary inducer blade according to the basic parameters of the conventional inducer;

[0020] S4, designing the secondary inducer blade according to the geometric parameters of the primary inducer blade;

[0021] S5, after obtaining the main body profile of the inducer blade, designing the circulation channel inside;

[0022] S6, arranging the grid structure in the circulation channel inside.

[0023] In summary, the application has at least one of the following beneficial technical effects:

[0024] 1. In actual use, the vapor bubbles generated by the primary inducer blade can be recycled in real time, introduced into the internal circulation channel through the secondary inducer blade, and largely eliminated in the circulation channel, thereby greatly reducing the number of vapor bubbles entering the main impeller, ensuring the performance of the main impeller and the performance of the unit.

[0025] 2. Two-stage grid structures with different blockage coefficients are arranged in the circulation channel, and the vapor bubbles are eliminated and broken as the shaft rotates, thereby achieving better elimination effect.

[0026] 3. The primary inducer blade is limited by the inlet and outlet installation angle to achieve a total pressure increase of about 3-50 meters. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a perspective view of the embodiment of the present application.

[0028] Figure 2 is a side view of the embodiment of the present application.

[0029] Figure 3 is a sectional view of the embodiment of the present application.

[0030] Figure 4 is a structure diagram of the two-stage grid structure in the embodiment of the present application.

[0031] Figure 5 is a structure diagram of the one-stage grid structure in the embodiment of the present application.

[0032] Figure 6 is a structure diagram of the embodiment of the present application in use.

[0033] Figure 7 is a design flowchart of the embodiment of the present application.

[0034] BRIEF DESCRIPTION OF DRAWINGS

[0035] 1. main body; 2. primary inducer blade; 3. secondary inducer blade; 4. circulation channel; 5. vapor bubble inlet; 6. vapor bubble outlet; 7. one-stage grid structure; 8. two-stage grid structure; 9. grid bar; 10. flow channel. DETAILED DESCRIPTION

[0036] The following will be described in detail in combination with the accompanying drawings. Figures 1-7 The present application will be further described in detail.

[0037] A two-stage inducer structure with vapor bubble suppression effect, as shown in Figures 1-3As shown, including the central columnar body 1, the outer diameter of the body 1 gradually increases from one end to the other end, the small end of the outer diameter of the body 1 is the water inlet end, the body 1 is provided with a primary inducer blade 2 and a secondary inducer blade 3 on one side along the axis direction of the water inlet of the body 1, the primary inducer blade 2 and the secondary inducer blade 3 are both spiral blades, and are evenly distributed around the axis of the body 1, 2-4 in this embodiment, the secondary inducer blade 3 is smaller than the primary inducer blade 2, a circulating channel 4 is opened in the inner center of the body 1, the length direction of the circulating channel 4 is arranged along the axial direction of the body 1, in addition, a bubble inlet 5 is opened in the end of the body 1 and communicates with the circulating channel 4, a bubble outlet 6 is opened in the head of the body 1 and communicates with the circulating channel 4, the bubble inlet 5 and the bubble outlet 6 are both evenly distributed around the circumference of the body 1, and a bubble breaking structure is arranged in the circulating channel 4 to break the bubbles, the bubble outlet 6 is radially opened on the body 1, and the bubble inlet 5 is obliquely opened on the body 1.

[0038] As shown in Figure 6 , the actual use can recycle the bubbles generated by the primary inducer blade 2 in real time, introduce them into the internal circulating channel 4 through the secondary inducer blade 3, and eliminate a large number of bubbles in the circulating channel 4, so as to finally greatly reduce the number of bubbles entering the main impeller, and well guarantee the performance of the main impeller and the performance of the unit.

[0039] As shown in Figures 1-3 , the primary inducer blade 2 is a variable pitch structure, the number of blades is 2-4, the leading edge wrap angle of the blade is 60°-120°, the blade rim wrap angle is 150°-350°, the inlet and outlet structures are limited by the inlet and outlet installation angles, the inlet installation angle is 8°-18°, and the outlet installation angle is 25°-70°, so as to realize the pressure increase of the overall head of about 3-50 meters.

[0040] As shown in Figures 1-3 , the secondary inducer blade 3 starts from the middle position of the outlet flow channel of the primary inducer blade 2, the front end installation angle is large, the rear end installation angle is small, the inlet installation angle of the secondary inducer blade 3 is in the range of 30°-60°, the outlet installation angle is in the range of 15°-30°, and the wrap angle is in the range of 150°-180°, and the bubble inlet 5 is located at the outlet flow channel of the secondary inducer blade 3, the center line of the bubble inlet 5 is close to the extension line direction of the outlet flow channel of the secondary inducer blade 3 and forms a spiral cutting structure, so that in actual use, the secondary inducer blade 3 can guide the bubbles to enter the circulating channel 4 from the bubble inlet 5 to achieve the purpose of backflow and elimination.

[0041] As shown in Figure 4 and Figure 5As shown, the bubble breaking structure in the embodiment includes a first grid structure 7 and a second grid structure 8, the first grid structure 7 and the second grid structure 8 are spaced along the direction of the circulation channel 4, wherein the first grid structure 7 has 4 grid bars 9 in the center and forms 4 flow channels 10 for the medium to pass through, and the second grid structure 8 has 5 grid bars 9 in the center and forms 5 flow channels 10 for the medium to pass through, the first grid structure 7 and the second grid structure 8 are fixed in the circulation channel 4 of the main body 1 and rotate with the main body 1, the blockage coefficient of the first grid structure 7 is less than that of the second grid structure 8, and the blockage coefficient of the first grid structure 7 is 0.6-0.8 times the blockage coefficient of the second grid structure 8; in this way, the small blockage coefficient of the first grid structure 7 facilitates the entry of large bubbles, and it is also the position of the first bubble breaking, and the second grid structure 8 is the position for further eliminating smaller bubbles, realizing more comprehensive elimination of bubbles and achieving the purpose of two-stage elimination.

[0042] As shown in the figure, Figures 1-3 In the embodiment, the circulation channel 4 is a tapered channel, and the diameter of the circulation channel 4 gradually decreases from the end close to the bubble inlet 5 to the other end. Since the vapor-liquid mixture breaks bubbles when passing through the bubble breaking structure, the volume flow rate decreases, so the volume flow rate decreases in the circulation channel 4. The tapered circulation channel 4 can be well adapted to this. The circulation channel 4 flow is 3%-5% of the total pump flow, and the above geometric parameters satisfy the relationship q=(3%-5%)Q / N; wherein Q is the total pump flow, N is the number of bubble inlets 5, and q is the flow rate of each bubble inlet 5. In this way, the circulation flow rate is neither too small nor too large. If the circulation flow rate is too small, it will be difficult for the bubbles to return and eliminate. If the circulation flow rate is too large, the volume loss will be large.

[0043] As shown in the figure, Figures 1-3 In the embodiment, the diameter of the bubble inlet 5 is larger than the diameter of the bubble outlet 6, the diameter of the bubble inlet 5 is d1, the diameter of the bubble outlet 6 is d2, and d1=nd2 (n=1.5-2). In this way, the diameter of the bubble outlet 6 is small, which can effectively reduce the damage to the flow field of the inducer inlet.

[0044] As shown in the figure, Figure 7 A design method of a two-stage inducer structure with bubble suppression effect, comprising the following steps:

[0045] S1, determining the design target and determining the basic parameters of the pump;

[0046] First, determine the design target: the basic parameters of the pump, such as flow rate Q, head H, speed n, NPSHr, efficiency, and medium properties.

[0047] S2, calculating and determining the basic parameters of the conventional inducer according to the basic parameters of the pump;

[0048] According to the initial data, the parameters of the conventional inducer are calculated by referring to the manuals such as Modern Pump Theory and Design, including the inlet diameter D1, the outlet diameter D2, the blade inlet angle β1, the blade outlet angle β2, the hub and shroud wrap angle, the throw ratio, the pitch, and other basic parameters of the inducer design.

[0049] S3, the first-stage inducer blade 2 is designed according to the basic parameters of the conventional inducer;

[0050] According to the geometric parameters of the conventional inducer, the first-stage inducer blade 2 is designed, the inlet velocity u1 = nπD1 / 60 is calculated, the blade leading edge wrap angle is 60°-120°, the blade shroud wrap angle is 150°-350°, the inlet and outlet structures are limited by the inlet and outlet setting angles, the inlet setting angle is 8°-18°, the outlet setting angle is 25°-70°, and the pressure boost of the overall head of 3-50 meters is realized.

[0051] S4, the second-stage inducer blade 3 is designed according to the geometric parameters of the first-stage inducer blade 2;

[0052] According to the geometric parameters of the first-stage inducer, the second-stage inducer blade 3 is designed, the second-stage inducer blade 3 starts from the middle position of the tail flow passage 10 of the first-stage inducer, the front end setting angle is large, the rear end setting angle is small, the inlet setting angle ranges from 30° to 60°, the outlet setting angle ranges from 15° to 30°, and the wrap angle ranges from 150° to 180°.

[0053] S5, the internal circulation passage 4 is designed after the main profile of the inducer blade is obtained;

[0054] The main profile of the inducer blade of the present application is obtained through the above steps, and the design of the internal circulation passage 4 of the inducer is further determined. The radial bubble inlet 5 is arranged at the outlet hub position of the second-stage inducer blade 3, the center line of the bubble inlet 5 is close to the extension line direction of the outlet flow passage 10 of the second-stage inducer blade 3, a spiral cut-in structure is formed, and the bubble outlet 6 is arranged at the left inlet position of the first-stage inducer blade 2. The hole diameter of the bubble inlet 5 is about d1, the hole diameter of the bubble outlet 6 is about d2, the shape of the circulation passage 4 is gradually contracted, and the flow rate of the circulation passage 4 is 3%-5% of the total flow rate of the pump. The inlet flow rate is q = (3%-5%)Q / N, the hole diameter of the bubble inlet 5 is d1 = nd2 (n = 1.5-2), the inlet velocity u2 = (0.6-0.8)u1, and the hole diameter of the bubble outlet 6 is d2 = 4*(3%-5%)Q / (πnu2).

[0055] S6, a grid structure is arranged in the internal circulation passage 4.

[0056] After the circulation channel 4 inside the main body 1 of the inducer is designed, two-stage grid structures are arranged on the circulation channel 4 inside the main body 1 of the inducer. At the same rotating speed, the grid blockage coefficient near the bubble inlet 5 is less than that at the bubble outlet 6. The grid blockage coefficient at the bubble inlet 5 is φ1, and the grid blockage coefficient at the bubble outlet 6 is φ2, wherein the relationship is φ1=(0.6-0.8)φ2.

[0057] The above are preferred embodiments of the present application, and do not limit the protection scope of the present application. Any equivalent changes made on the basis of the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A two-stage inducer wheel structure having a vapor bubble suppression effect, characterized by: The utility model provides a kind of pump inducer, including main body (1), the main body (1) is sequentially provided with primary inducer blade (2) and secondary inducer blade (3) along its axial, the inside of the main body (1) is opened with circulation channel (4), the end of the main body (1) is opened with steam bubble inlet (5) with circulation channel (4) intercommunication, the first end of the main body (1) is opened with steam bubble outlet (6) with circulation channel (4) intercommunication, the inside of the circulation channel (4) is provided with steam bubble breaking structure, the steam bubble breaking structure includes primary grid structure (7) and secondary grid structure (8), the blockage coefficient of the primary grid structure (7) is less than the blockage coefficient of secondary grid structure (8).

2. A two-stage inducer wheel structure having a bubble suppression effect according to claim 1, characterized in that: The secondary inducer blade (3) is smaller than the primary inducer blade (2).

3. A two-stage inducer wheel structure having a bubble suppression effect according to claim 1, characterized in that: The primary inducer blade (2) and the secondary inducer blade (3) are both spiral blades, and the primary inducer blade (2) and the secondary inducer blade (3) are both distributed with at least two pieces around the circumference.

4. A two-stage inducer wheel structure having a bubble suppression effect according to claim 1, characterized in that: The leading edge wrap angle of the primary inducer blade (2) is 60°-120°, the rim wrap angle is 150°-350°, the inlet setting angle is 8°-18°, and the outlet setting angle is 25°-70°.

5. A two-stage inducer wheel structure having a bubble suppression effect according to claim 1, characterized in that: The leading end setting angle of the secondary inducer blade (3) is greater than the trailing end setting angle, the inlet setting angle of the secondary inducer blade (3) is 30°-60°, the outlet setting angle is 15°-30°, and the wrap angle is 150°-180°.

6. A two-stage inducer wheel structure having a bubble suppression effect according to claim 1, characterized in that: The secondary inducer blade (3) starts from the middle position of the outlet flow passage of the primary inducer blade (2), the steam bubble inlet (5) is located at the outlet flow passage of the secondary inducer blade (3), and the center line of the steam bubble inlet (5) is close to the extension line direction of the outlet flow passage of the secondary inducer blade (3) and forms a spiral cutting inlet structure.

7. A two-stage inducer wheel structure having a bubble suppression effect according to claim 1, characterized in that: The steam bubble inlet (5) and the steam bubble outlet (6) are uniformly distributed with multiple around the circumference of the main body (1), the diameter of the steam bubble inlet (5) is greater than the diameter of the steam bubble outlet (6), the steam bubble outlet (6) is radially opened on the main body (1), and the steam bubble inlet (5) is obliquely opened on the main body (1).

8. A two-stage inducer wheel structure having a bubble suppression effect according to claim 1, characterized in that: The circulation channel (4) is a reducing channel, the diameter of the circulation channel (4) gradually decreases from one end close to the steam bubble inlet (5) to the other end, and the flow rate of the circulation channel (4) is 3%-5% of the total flow rate of the pump.

9. A design method applied to the two-stage inducer structure with bubble suppression effect according to claim 1, characterized in that, The method comprises the following steps: S1, clearly design target and determine the basic parameters of the pump; S2, calculate and determine the basic parameters of the conventional inducer according to the basic parameters of the pump; S3, design the primary inducer blade (2) according to the basic parameters of the conventional inducer; S4, design the secondary inducer blade (3) according to the geometric parameters of the primary inducer blade (2); S5, design the internal circulation channel (4) after obtaining the main body profile of the inducer blade; S6, arrange the grid structure in the internal circulation channel (4).

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