Vibration reduction optimization structure for open impeller of centrifugal pump under low-flow working condition

Abstract

The invention relates to the field of centrifugal pumps, in particular to a centrifugal pump open type impeller low-flow working condition vibration reduction optimization structure which comprises an impeller, the impeller is provided with a rear cover plate, a plurality of blades which are evenly arranged at intervals in the circumferential direction are fixedly installed on one side of the rear cover plate, and notches are formed in the sides, away from the rear cover plate, of the blades; the internal flow stability of the impeller can be obviously improved, the torque fluctuation of the pump shaft is inhibited, the vibration of the pump under the low-flow working condition is improved, and the running stability of the pump is improved.

Description

Technical Field

[0001] This invention relates to the field of centrifugal pumps, and more specifically to a vibration reduction and optimization structure for an open impeller of a centrifugal pump under low flow conditions. Background Technology

[0002] An open impeller in a centrifugal pump is a type of impeller without a front cover plate. Because there is no front cover plate, there is a gap between the blade tips and the pump body, known as the tip clearance. Due to this tip clearance, fluid leaks through it during impeller rotation, forming leakage vortices. The formation and rupture of these vortices cause pressure pulsations, resulting in pump vibration. Traditional vibration reduction methods (such as cutting the entire impeller height) are effective, but they suffer from significant head and efficiency losses. Summary of the Invention

[0003] The purpose of this invention is to provide a vibration reduction and optimization structure for an open impeller of a centrifugal pump under low flow conditions, which improves flow stability through blade notch design to solve the defects mentioned in the background art.

[0004] To achieve the above object, the present invention provides the following technical solutions: A vibration reduction and optimization structure for an open impeller of a centrifugal pump under low flow conditions includes an impeller with a rear cover plate. A plurality of blades are fixedly installed on one side of the rear cover plate at uniform intervals in the circumferential direction, and a notch is provided on the side of the blades away from the rear cover plate.

[0005] As a further improvement, the rear cover plate has a central shaft hole, and the blade extends from the shaft hole to the edge of the rear cover plate.

[0006] As a further improvement, the blades are positioned at the same height along the impeller axis.

[0007] As a further improvement, the height of the blade along the impeller axis is H, and the depth of the notch along the impeller axis is H1, where H1 = 1 / 3 * H.

[0008] As a further improvement, the diameter of the impeller is D, and the diameter of the inner circle containing the plurality of notches is D2, where D2≥2 / 3*D and D2≤0.7D.

[0009] As a further improvement, the diameter of the outer circle containing the multiple notches is D1, where D1 ≥ 0.1 * D + D2.

[0010] As a further improvement, D1≤0.95D.

[0011] Compared with the prior art, the beneficial effects of the present invention are: This invention can significantly improve the internal flow stability of the impeller, suppress pump shaft torque fluctuations, thereby improving pump vibration under low flow conditions and enhancing pump operation stability. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a structural schematic diagram of an embodiment of the present invention.

[0014] In the diagram: 1-Impeller; 2-Rear cover plate; 3-Blade; 4-Notch; 5-Shaft hole; 6-Pump casing. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0016] like Figure 1 As shown, a vibration reduction and optimization structure for an open impeller of a centrifugal pump under low flow conditions includes an impeller 1. The impeller 1 is provided with a circular rear cover plate 2. Multiple blades 3 are welded on the side of the rear cover plate 2 near the pump casing 6, and the blades 3 are provided with a notch 4 on the side of the blades 3 near the pump casing 6.

[0017] The rear cover plate 2 has a shaft hole 5 at its center, and the blade 3 extends from the shaft hole 5 to the edge of the rear cover plate 2.

[0018] The blades 3 are at the same height along the axial direction of the impeller 1 at all positions, and there is a blade tip clearance L between the blades 3 and the pump casing 6.

[0019] The height of blade 3 along the axial direction of impeller 1 is H, and the depth of notch 4 along the axial direction of impeller 1 is H1, where H1 = 1 / 3 * H.

[0020] The diameter of impeller 1 is D, the outer diameter of the back cover plate 2 is the diameter of impeller 1, and the diameter of the inner circle containing the multiple notches 4 is D2, where D2≥2 / 3*D and D2≤0.7D.

[0021] The diameter of the outer circle containing multiple notches 4 is D1, where D1≥0.1*D+D2 and D1≤0.95D.

[0022] Taking the JHXL20-40 pump as an example (D=295mm, H=30mm), with a speed of 1450RPM, the original design was for a head of 30 meters when the flow rate Qc was 50 cubic meters. According to the customer's operating point requirements, the rated flow rate needs to be changed to 20 cubic meters. At this point, the pump exhibits significant vibration and noise. To meet the usage requirements, a vibration reduction modification design is needed. The traditional modification solution is to cut the impeller height as a whole. After the blades are cut by 5mm, the vibration basically meets the requirements.

[0023] To illustrate the design effect of this invention, a comparative analysis is conducted with the aforementioned traditional modification schemes. Option 1: D2≥2 / 3*D and D2≤0.7D, D2 is taken as the middle value of 200mm, D1≥0.1*D+D2, D1 is rounded to 260mm, H1=1 / 3*H=10mm; Option 2: D2≥2 / 3*D and D2≤0.7D, D2 takes the median value of 200mm, D1≥0.1*D+D2, D1 takes 270mm, H1=1 / 3*H=10mm; Option 3: D2≥2 / 3*D and D2≤0.7D, take the middle value of D2 as 200mm, D1≤0.95D, round D1 to 280mm, H1=1 / 3*H=10mm.

[0024] Transient numerical calculations of the pump were performed using CFD. The vibration reduction effect of the pump was analyzed using the collected instantaneous torque data (collection frequency 2000Hz) and the torque standard deviation. The standard deviation formula is as follows: S 2 Let X be the sample variance, and X be the variable. Here, n is the sample mean, and n is the number of samples. The CFD calculation results at the rated flow point are shown in the table below: As can be seen, compared with the traditional modification scheme (cutting the impeller height as a whole), the torque standard deviation of the first scheme of the present invention is close to that of the traditional modification scheme, and the reduction in head and efficiency are better than those of the traditional modification scheme, indicating that the first scheme of the present invention is better when achieving the same vibration reduction effect.

[0025] The standard deviation of torque in Scheme 2 and Scheme 3 of the present invention is further reduced, and the head difference and efficiency difference in Scheme 3 are close to those of the traditional modification scheme, indicating that Scheme 2 and Scheme 3 of the present invention also have certain vibration reduction advantages.

[0026] The CFD calculation results for different flow points are shown in the table below: The first solution of the present invention has a vibration reduction effect in both low flow conditions (Q=0.8Qc) and high flow conditions (Q=1.2Qc). The head decrease is less in the low flow condition (Q=0.8Qc), indicating that the present invention has certain advantages for the modification of open impellers of centrifugal pumps under low flow conditions.

[0027] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A vibration reduction and optimization structure for an open impeller of a centrifugal pump under low flow conditions, characterized in that: Includes an impeller (1), the impeller (1) is provided with a rear cover plate (2), a plurality of blades (3) are fixedly installed on one side of the rear cover plate (2) and evenly spaced in the circumferential direction, and the blades (3) are provided with a notch (4) on the side away from the rear cover plate (2).

2. The vibration reduction and optimization structure for an open impeller of a centrifugal pump under low flow conditions as described in claim 1, characterized in that: The rear cover plate (2) has a shaft hole (5) at its center, and the blade (3) extends from the shaft hole (5) to the edge of the rear cover plate (2).

3. The vibration reduction and optimization structure for an open impeller of a centrifugal pump under low flow conditions as described in claim 1, characterized in that: The blades (3) are at the same height along the axial direction of the impeller (1) at each position.

4. The vibration reduction and optimization structure for an open impeller of a centrifugal pump under low flow conditions as described in claim 3, characterized in that: The height of the blade (3) along the axial direction of the impeller (1) is H, and the depth of the notch (4) along the axial direction of the impeller (1) is H1, where H1 = 1 / 3 * H.

5. The vibration reduction and optimization structure for an open impeller of a centrifugal pump under low flow conditions as described in claim 1, characterized in that: The diameter of the impeller (1) is D, and the diameter of the inner circle where the multiple notches (4) are located is D2, where D2≥2 / 3*D and D2≤0.7D.

6. The vibration reduction and optimization structure for an open impeller of a centrifugal pump under low flow conditions as described in claim 5, characterized in that: The diameter of the outer circle where the multiple notches (4) are located is D1, D1≥0.1*D+D2.

7. The vibration reduction and optimization structure for an open impeller of a centrifugal pump under low flow conditions as described in claim 6, characterized in that: D1≤0.95D.

Images