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

Abstract

The invention discloses a two-stage inducer structure with a bubble inhibition effect and a design method thereof, the two-stage inducer structure comprises a main body, the main body is sequentially provided with a first-stage inducer blade and a second-stage inducer blade along the axial direction, the main body is internally provided with a circulation channel, the tail end of the main body is provided with a bubble inlet communicated with the circulation channel, and the bubble inlet is communicated with the circulation channel. The head end of the main body is provided with a steam bubble outlet communicated with the circulation channel, a steam bubble breaking structure is arranged in the circulation channel, steam bubbles generated by the first-stage inducer blade can be recycled in real time in actual use, the steam bubbles are introduced into the internal circulation channel through the second-stage inducer blade, and a large number of steam bubbles are eliminated in the circulation channel. Finally, the number of bubbles entering the main impeller is greatly reduced, and the performance of the main impeller and the performance of a unit are well guaranteed.

Description

Technical Field

[0001] The invention relates to the field of inducer wheels, and in particular to a two-stage inducer wheel structure with bubble suppression function and a design method thereof. Background Art

[0002] The inducer is a device used to improve the suction performance of the pump, usually installed in front of the first-stage impeller of the centrifugal pump. The liquid entering the pump is treated in advance to improve the working condition of the pump. From the structural point of view, it is similar to a small axial flow impeller with a hub and several twisted blades. The inducer is widely used in high-speed pumps and low NPSH occasions. Due to its own head, it significantly increases the inlet pressure of the main impeller, and realizes the stable output of pump performance under large flow, low NPSH and high speed conditions.

[0003] However, in reality, the inducer often operates under a certain degree of cavitation, which will produce more bubbles on the back of its inlet blades. Some bubbles will burst due to the increase in pressure before entering the main impeller, and some bubbles will flow into the downstream main impeller flow channel and collapse in the middle and downstream of the flow channel, causing great damage to the fluid transport performance and structure, affecting the life of the unit. Summary of the invention

[0004] In order to better guarantee 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 solution: A two-stage inducer structure with bubble suppression function comprises a main body, wherein the main body is provided with a primary inducer blade and a secondary inducer blade in sequence along its axial direction, a circulation channel is provided inside the main body, a bubble inlet connected to the circulation channel is provided at the rear end of the main body, a bubble outlet connected to the circulation channel is provided at the front end of the main body, and a bubble crushing structure is provided inside the circulation channel.

[0006] Optionally, the secondary inducer blades are smaller than the primary inducer blades.

[0007] Optionally, the first-stage inducer blades and the secondary inducer blades are both spiral blades, and there are at least two first-stage inducer blades and two secondary inducer blades distributed around the circumference.

[0008] Optionally, the leading edge wrap angle of the first-stage inducer blade is 60°-120°, the rim wrap angle is 150°-350°, the inlet placement angle is 8°-18°, and the outlet placement angle is 25°-70°.

[0009] Optionally, the front end placement angle of the secondary inducer blade is greater than the rear end placement angle, the inlet placement angle of the secondary inducer blade is 30°-60°, the outlet placement angle is 15°-30°, and the wrap angle is 150°-180°.

[0010] Optionally, the secondary inducer blade starts at the middle position of the outlet flow channel of the first-stage inducer blade, the bubble inlet is located at the outlet flow channel of the secondary inducer blade, the center line of the bubble inlet is close to the extension line of the outlet flow channel of the secondary inducer and forms a spiral inlet structure.

[0011] Optionally, the bubble breaking structure includes a primary grid structure and a secondary grid structure, and a blockage coefficient of the primary grid structure is smaller than a blockage coefficient of the secondary grid structure.

[0012] Optionally, the bubble inlet and the bubble outlet are uniformly distributed around the circumference of the main body, the caliber of the bubble inlet is larger than the caliber of the bubble outlet, the bubble outlet is radially opened on the main body, and the bubble inlet is obliquely opened on the main body.

[0013] Optionally, the circulation channel is a reducing channel, the diameter of the circulation channel gradually decreases from one end close to the 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.

[0014] The present application also provides a design method for a two-stage inducer structure with a bubble suppression effect, which adopts the following technical solution: A design method for a two-stage inducer structure with a bubble suppression effect comprises the following steps: S1, clarify the design objectives 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 first stage inducer blades according to the basic parameters of conventional inducers; S4, designing the secondary inducer blades according to the geometric parameters of the first-stage inducer blades; S5, after obtaining the main contour of the inducer blade, design the internal circulation channel; S6, a grid structure is arranged in the internal circulation channel.

[0015] In summary, the present application includes at least one of the following beneficial technical effects: 1. In actual use, the bubbles generated by the first-stage inducer blades can be recovered in real time, introduced into the internal circulation channel through the secondary inducer blades, and a large number of bubbles are eliminated in the circulation channel, ultimately greatly reducing the number of bubbles entering the main impeller, thus well ensuring the performance of the main impeller and the performance of the unit; 2. Two levels of grid structures with different blockage coefficients are arranged in the circulation channel, which can realize the function of bubble elimination and crushing as the shaft system rotates, thereby achieving a better elimination effect; 3. The first-stage inducer blades are limited by the inlet and outlet placement angles to achieve an overall pressurization of approximately 3-50 meters head. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a stereogram of an embodiment of the present application.

[0017] Figure 2 It is a side view of an embodiment of the present application.

[0018] Figure 3 It is a cross-sectional view of an embodiment of the present application.

[0019] Figure 4 It is a structural diagram of the secondary grid structure in the embodiment of the present application.

[0020] Figure 5 It is a structural diagram of the primary grid structure in an embodiment of the present application.

[0021] Figure 6 It is a schematic diagram of the structure when used in the embodiment of the present application.

[0022] Figure 7 It is a design flow chart of an embodiment of the present application.

[0023] Description of reference numerals: 1. Main body; 2. First-stage inducer blades; 3. Secondary inducer blades; 4. Circulation channel; 5. Bubble inlet; 6. Bubble outlet; 7. First-stage grid structure; 8. Secondary grid structure; 9. Grid bars; 10. Flow channel. DETAILED DESCRIPTION

[0024] The following is combined with Figure 1-7 This application is described in further detail.

[0025] A two-stage inducer structure with bubble suppression effect, such as Figure 1-Figure 3As shown, it includes a central columnar body 1, the outer diameter of the body 1 gradually increases from one end to the other end, the end of the body 1 with a smaller outer diameter is the water inlet end, and the main body 1 is provided with a first-stage inducer blade 2 and a secondary inducer blade 3 on one side along the axial direction of the water inlet, the first-stage inducer blade 2 and the secondary inducer blade 3 are both spiral blades, and 2-4 of them are evenly distributed around the circumference of the axis of the main body 1. In this embodiment, the secondary inducer blade 3 is smaller than the first-stage inducer blade 2, and a circulation channel 4 is opened at the inner center of the main body 1, and the length direction of the circulation channel 4 is arranged along the axial direction of the main body 1. In addition, a bubble inlet 5 connected with the circulation channel 4 is opened at the end of the main body 1, and a bubble outlet 6 connected with the circulation channel 4 is opened at the head end of the main body 1. Both the bubble inlet 5 and the bubble outlet 6 are evenly distributed around the circumference of the main body 1, and a bubble crushing structure for crushing bubbles is arranged inside the circulation channel 4, the bubble outlet 6 is radially opened on the main body 1, and the bubble inlet 5 is inclinedly opened on the main body 1.

[0026] like Figure 6 As shown, in actual use, the bubbles generated by the first-stage inducer blades 2 can be recovered in real time, introduced into the internal circulation channel 4 through the secondary inducer blades 3, and a large number of bubbles are eliminated in the circulation channel 4, ultimately greatly reducing the number of bubbles entering the main impeller, thereby well ensuring the performance of the main impeller and the performance of the unit.

[0027] like Figure 1-Figure 3 As shown, the first-stage inducer blade 2 is a variable pitch structure, with 2-4 blades, the leading edge wrap angle of the blade is 60°-120°, the blade rim wrap angle is 150°-350°, and the inlet and outlet structure is limited by the inlet and outlet installation angles, the inlet installation angle is 8°-18°, and the outlet installation angle is 25°-70°, achieving an overall pressurization of about 3-50 meters head.

[0028] like Figure 1-Figure 3 As shown, secondary inducer blade 3 starts at the middle position of the outlet flow channel of primary inducer blade 2, with a large front end placement angle and a small rear end placement angle. The inlet placement angle of secondary inducer blade 3 is in the range of 30°-60°, the outlet placement angle is in the range of 15°-30°, the wrap angle is in the range of 150°-180°, and bubble inlet 5 is located at the outlet flow channel of secondary inducer blade 3. The center line of bubble inlet 5 is close to the direction of the extension line of the outlet flow channel of secondary inducer blade 3 and forms a spiral cut-in structure. In this way, in actual use, secondary inducer blade 3 can well guide bubbles from bubble inlet 5 into circulation channel 4 to achieve the purpose of backflow and elimination.

[0029] like Figure 4 and Figure 5As shown, in this embodiment, the bubble crushing structure includes a primary grid structure 7 and a secondary grid structure 8, and the primary grid structure 7 and the secondary grid structure 8 are spaced apart along the direction of the circulation channel 4, wherein the primary grid structure 7 has 4 grid bars 9 at the center and forms 4 flow channels 10 for the medium to pass through, wherein the secondary grid structure 8 has 5 grid bars 9 at the center and forms 5 flow channels 10 for the medium to pass through, and both the primary grid structure 7 and the secondary grid structure 8 are fixed in the circulation channel 4 of the main body 1 and rotate with the main body 1. In this embodiment, the blocking coefficient of the primary grid structure 7 is smaller than the blocking coefficient of the secondary grid structure 8, and the blocking coefficient of the primary grid structure 7 is 0.6-0.8 times that of the blocking coefficient of the secondary grid structure 8; in this way, the small blocking coefficient of the primary grid structure 7 is convenient for large bubbles to enter, and is also the position of the primary crushed bubbles, and the secondary grid structure 8 is the position for further eliminating smaller bubbles, so as to achieve a more comprehensive elimination of bubbles and achieve the purpose of secondary elimination.

[0030] like Figure 1-Figure 3 As shown, in this embodiment, the circulation channel 4 is a reduction channel, and the diameter of the circulation channel 4 gradually decreases from one end close to the bubble inlet 5 to the other end. Since the bubbles burst and the volume flow rate decreases when the gas-liquid mixture passes through the bubble crushing structure, the volume flow rate in the circulation channel 4 is a process of decreasing, and the reduction type circulation channel 4 can be well applied to this; the flow rate of the circulation channel 4 is 3%-5% of the total flow rate of the pump, and the above-mentioned geometric parameters satisfy the relationship q=(3%-5%)Q / N; wherein Q is the total flow rate of the pump, N is the number of bubble inlets 5, and q is the flow rate of each bubble inlet 5, so that the circulation flow rate is neither too small nor too large, because if the circulation flow rate is too small, it will make it difficult to eliminate the bubbles by reflux, and if the circulation flow rate is too large, the volume loss will be relatively large.

[0031] like Figure 1-Figure 3 As shown, in this embodiment, the caliber of the bubble inlet 5 is larger than the caliber of the bubble outlet 6. The caliber of the bubble inlet 5 is d1, and the caliber of the bubble outlet 6 is d2, d1=nd2 (n=1.5-2). In this way, the caliber of the bubble outlet 6 is smaller, which can effectively reduce the damage to the flow field at the inlet of the inducer.

[0032] like Figure 7 As shown, a design method of a two-stage inducer structure with bubble suppression effect comprises the following steps: S1, clarify the design objectives and determine the basic parameters of the pump; First determine the design goals: the basic parameters of the pump flow Q, head H, speed n, NPSHr, efficiency, and medium properties.

[0033] S2, calculate and determine the basic parameters of the conventional inducer according to the basic parameters of the pump; Based on the initial data, the conventional inducer parameters are calculated with reference to manuals such as "Modern Pump Theory and Design", including the inlet diameter D1, outlet diameter D2, blade inlet angle β1, blade outlet angle β2, rim, hub wrap angle, displacement coefficient, pitch and other basic design parameters of the inducer.

[0034] S3, designing the first-stage inducer blade 2 according to the basic parameters of a conventional inducer; According to the geometric parameters of the above-mentioned 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 rim wrap angle is 150°-350°, and its inlet and outlet structure is 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 achieve an overall pressurization of about 3-50 meters head.

[0035] S4, designing the secondary inducer blade 3 according to the geometric parameters of the primary inducer blade 2; According to the geometric parameters of the first-stage inducer, the secondary inducer blade 3 is designed. The secondary inducer blade 3 starts from the middle position of the first-stage inducer tail flow channel 10, has a large front end placement angle, a small rear end placement angle, an inlet placement angle range of 30°-60°, an outlet placement angle of 15°-30°, and a wrap angle of 150°-180.

[0036] S5, after obtaining the main contour of the inducer blade, design the internal circulation channel 4; Through the above steps, the main contour of the inducer blade of the present invention is obtained, and the design of the internal circulation channel 4 of the inducer is further determined. A radial bubble inlet 5 is arranged at the outlet hub position of the secondary inducer blade 3, and the center line of the bubble inlet 5 is close to the extension line direction of the outlet flow channel 10 of the secondary inducer blade 3, forming a spiral inlet structure, and a bubble outlet 6 is arranged at the left inlet position of the first-stage inducer blade 2. The aperture of the bubble inlet 5 is about d1, the aperture of the bubble outlet 6 is about d2, and the shape of the circulation channel 4 gradually shrinks, so that the flow rate of the circulation channel 4 is 3%-5% of the total flow rate of the pump. The inlet flow rate is q=(3%-5%)Q / N, the aperture size of the bubble inlet 5 is d1=nd2(n=1.5~2), the inlet speed u2=(0.6-0.8)u1, and the aperture size of the bubble outlet 6 is d2=4*(3%~5%)Q / (πnu2).

[0037] S6, arranging a grid structure in the internal circulation channel 4.

[0038] After the design of the internal circulation channel 4 of the main body 1 of the inducer is completed, a two-stage grid structure is arranged on the circulation channel 4 inside the main body 1 of the inducer, and at the same speed, the grid blockage coefficient near the bubble inlet 5 is smaller 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.

[0039] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A two-stage inducer structure with bubble suppression function, characterized in that: The invention comprises a main body (1), wherein the main body (1) is provided with a primary inducer blade (2) and a secondary inducer blade (3) in sequence along its axial direction, wherein a circulation channel (4) is provided inside the main body (1), wherein a bubble inlet (5) communicating with the circulation channel (4) is provided at the rear end of the main body (1), wherein a bubble outlet (6) communicating with the circulation channel (4) is provided at the front end of the main body (1), and wherein a bubble crushing structure is provided inside the circulation channel (4).

2. A two-stage inducer structure with bubble suppression function according to claim 1, characterized in that: The secondary inducer blades (3) are smaller than the primary inducer blades (2).

3. The two-stage inducer structure with bubble suppression function according to claim 1, characterized in that: The first-stage inducer blade (2) and the secondary inducer blade (3) are both spiral blades, and at least two of the first-stage inducer blade (2) and the secondary inducer blade (3) are distributed around the circumference.

4. The two-stage inducer structure with bubble suppression function according to claim 1, characterized in that: The leading edge wrap angle of the first-stage inducer blade (2) is 60°-120°, the rim wrap angle is 150°-350°, the inlet placement angle is 8°-18°, and the outlet placement angle is 25°-70°.

5. The two-stage inducer structure with bubble suppression function according to claim 1, characterized in that: The front end placement angle of the secondary inducer blade (3) is greater than the rear end placement angle, the inlet placement angle of the secondary inducer blade (3) is 30°-60°, the outlet placement angle is 15°-30°, and the wrap angle is 150°-180°.

6. The two-stage inducer structure with bubble suppression function according to claim 1, characterized in that: The secondary inducer blade (3) starts at the middle position of the outlet flow channel of the primary inducer blade (2), 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 direction of the extension line of the outlet flow channel of the secondary inducer blade (3), and a spiral inlet structure is formed.

7. The two-stage inducer structure with bubble suppression function according to claim 1, characterized in that: The bubble breaking structure comprises a primary grid structure (7) and a secondary grid structure (8), and the blockage coefficient of the primary grid structure (7) is smaller than the blockage coefficient of the secondary grid structure (8).

8. The two-stage inducer structure with bubble suppression function according to claim 1, characterized in that: The bubble inlet (5) and the bubble outlet (6) are both evenly distributed in plurality around the circumference of the main body (1); the caliber of the bubble inlet (5) is larger than the caliber of the bubble outlet (6); the bubble outlet (6) is radially opened on the main body (1); and the bubble inlet (5) is obliquely opened on the main body (1).

9. The two-stage inducer structure with bubble suppression function according to claim 1, characterized in that: The circulation channel (4) is a contraction channel, the diameter of which gradually decreases from one end close to the 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.

10. A design method for a two-stage inducer structure with bubble suppression effect, characterized in that: The following steps are involved: S1, clarify the design objectives 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, designing the first-stage inducer blades (2) according to basic parameters of a conventional inducer; S4, designing the secondary inducer blade (3) according to the geometric parameters of the primary inducer blade (2); S5, after obtaining the main contour of the inducer blade, designing the internal circulation channel (4); S6, arranging a grid structure in the internal circulation channel (4).

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