Jet device and jet centrifugal pump
By setting a check valve on the jet hose of the jet centrifugal pump, the valve plate status is automatically adjusted to increase the pressure in the low pressure area of the throat, the cavitation phenomenon that the jet centrifugal pump may occur under large flow conditions is solved, and the cavitation phenomenon is improved. Noise, head and efficiency issues.
Patent Information
- Application Number
- CN202411142041.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-20
- Publication Date
- 2025-02-18
AI Technical Summary
When the jet centrifugal pump is operating at a high flow operating point, the liquid pressure at the throat position may be lowered below the saturation pressure, resulting in cavitation, which in turn causes problems such as increased noise, head and efficiency.
Design a jet with a one-way valve on the throat. The one-way valve is closed under small flow conditions and opens automatically under large flow conditions. High-pressure liquid is introduced to increase the pressure in the low-pressure area of the throat and suppress airflow. Transformation phenomenon.
It effectively suppresses the occurrence of cavitation phenomenon, improves the reduction of noise, vibration, head and efficiency caused by cavitation, and improves the coverage area of the head curve.
Smart Images
Figure CN119467439A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of ejectors, and in particular to an ejector and a jet centrifugal pump. Background Art
[0002] The jet centrifugal pump is developed on the basis of the internal mixing centrifugal pump. It adds a self-circulating ejector with a "Venturi tube" at the inlet of the ordinary centrifugal pump. When the pump is started, the low pressure formed at the throat of the ejector accelerates the pump inlet pipeline gas suction, thereby improving the self-priming performance. The jet centrifugal pump has the advantages of light structure, simple operation, no need to fill water before each use, and can achieve self-priming. The pump is widely used in many industries and fields such as pure water systems, rural household well water pumping, floor pipeline pressurization, car spraying, oil tank pumping, fountains, gardening irrigation, etc. due to its strong low-level water extraction capacity and good self-priming performance. Research has found that the lowest internal pressure of the jet centrifugal pump occurs at the throat position during operation. When operating at a large flow rate operating point, it may cause the pressure in the liquid at this location to drop below the saturation pressure, thereby causing cavitation, and causing a series of hazards such as a sharp increase in noise, a sharp drop in head and efficiency. Summary of the invention
[0003] In view of the deficiencies in the prior art, one of the purposes of the present application is to provide an ejector and a jet centrifugal pump, which have the advantage of suppressing the occurrence of cavitation.
[0004] The above-mentioned purpose of the present application is achieved through the following technical solutions: An ejector comprises a throat pipe, wherein a one-way valve is arranged on the throat pipe and the one-way valve is unidirectionally conducted toward the throat pipe.
[0005] In a preferred example, the present application can be further configured as follows: the ratio of the distance from the location of the one-way valve to the throat inlet to the length of the throat is 1 / 6 to 1 / 3.
[0006] In a preferred example, the present application can be further configured as follows: a mounting hole is provided on the throat pipe, the one-way valve includes a valve plate, the valve plate is installed on the throat pipe, and the valve plate and the mounting hole constitute the one-way valve.
[0007] In a preferred example, the present application can be further configured as follows: the ratio of the diameter of the mounting hole to the diameter of the throat is 1 / 12 to 1 / 15.
[0008] In a preferred example, the present application can be further configured as follows: there are multiple one-way valves, which are distributed circumferentially on the throat.
[0009] In a preferred example, the present application can be further configured as follows: the thickness of the valve plate is 1 / 3 to 1 / 2 of the thickness of the ejector tube.
[0010] In a preferred example, the present application can be further configured as follows: the valve plate area is 1.5 to 2 times the installation hole area.
[0011] In a preferred example, the present application can be further configured as follows: the valve plate is a cantilever beam type, and the cross-sectional displacement of the valve plate is: In the formula: q is the uniformly distributed load acting on the valve plate; a is the length of the unstressed valve plate; c is the length of the stressed valve plate; E represents the elastic modulus; I is the moment of inertia of the section.
[0012] In a preferred example, the present application can be further configured as follows: Under the action of pressure, the flow rate through the valve plate can be expressed as Where: C is the flow coefficient, δ max is the maximum deflection of the cantilever valve end, ρ is the fluid density, r is the characteristic length of the cantilever, and ΔP is the pressure difference at both ends of the cantilever.
[0013] The present application also discloses a jet centrifugal pump, comprising an ejector as described in any one of the above items.
[0014] This application has at least the following advantages: The one-way valve is in a closed state when operating under low flow conditions, and will automatically open when operating under high flow conditions and when the pressure in the ejector is close to the cavitation low pressure, introducing the high-pressure liquid in the pump chamber into the low-pressure area of the ejector throat to increase the pressure in this area, thereby suppressing the occurrence of cavitation, improving the noise, vibration, head and efficiency drop caused by cavitation, and increasing the coverage area of the head curve. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 It is a schematic diagram of the cross-sectional structure of the throat pipe of this application.
[0016] Figure 2 It is a schematic diagram of the cross-sectional structure of the valve plate and the mounting hole of the present application.
[0017] Figure 3 This application adds a cavitation cloud map before the elastic valve plate.
[0018] Figure 4 This is the cavitation cloud diagram after the elastic valve plate is added in this application.
[0019] Figure numerals: 1, throat; 11, mounting hole; 2, one-way valve; 21, valve plate. DETAILED DESCRIPTION
[0020] The present application is further described in detail below in conjunction with the accompanying drawings.
[0021] Reference Figure 1-Figure 4 , is an ejector disclosed in the present application, comprising a throat 1, a one-way valve 2 is provided on the throat 1, and the one-way valve 2 is one-way toward the throat 1. The ratio of the distance from the location of the one-way valve 2 to the inlet of the throat 1 to the length of the throat 1 is 1 / 6 to 1 / 3. A mounting hole 11 is provided on the throat 1, and the one-way valve 2 comprises a valve plate 21, which is mounted on the throat 1. The thickness of the valve plate 21 is 1 / 3 to 1 / 2 of the thickness of the ejector tube, and the area of the valve plate 21 is 1.5 to 2 times the area of the mounting hole 11. The valve plate 21 and the mounting hole 11 constitute the above-mentioned one-way valve 2. In other embodiments, the one-way valve 2 can adopt an existing one-way valve and be mounted in the mounting hole 11.
[0022] The ratio of the diameter of the mounting hole 11 to the diameter of the throat 1 is 1 / 12 to 1 / 15. There are multiple one-way valves 2 distributed circumferentially on the throat 1. In the present embodiment, there are 2 to 4 one-way valves 2. In other embodiments, the number may be no less than 4.
[0023] The material of the valve plate 21 can be selected from beryllium bronze, PET (polyethylene terephthalate), PDMS (polydimethylsiloxane) and stainless steel, etc. The above materials can be selected from adhesives or bonding processes, or mechanical fixing methods such as screw fixing, welding fixing, etc. The valve plate 21 is a cantilever beam type, and the cross-sectional displacement of the valve plate 21 is: Where: q is the uniform load acting on the valve plate 21, in N / m; a is the length of the stress-free valve plate 21, in meters (m); c is the length of the stressed valve plate 21, in meters (m); E represents the elastic modulus, in Pa; I is the moment of inertia of the section, in m 4 , δ is the displacement of the free end, unit is m, δ max It is the maximum deflection of the cantilever valve end, in m.
[0024] Under the action of pressure, the flow rate through the valve plate 21 can be expressed as Where: C is the flow coefficient, δ max is the maximum deflection of the cantilever valve end, in m, and ρ is the fluid density, in kg / m 3 , r is the characteristic length of the cantilever beam, that is, the distance from the fixed end to the free end, the unit is meter (m), ΔP is the pressure difference between the two ends of the cantilever beam, the unit is Pascal (Pa).
[0025] The present application also discloses a jet centrifugal pump, comprising the above-mentioned ejector.
[0026] In this embodiment, the number of mounting holes 11 and elastic valve disc 21 is 2, which are evenly distributed along the circumference. The ratio of the distance from the boost hole position to the throat pipe 1 inlet to the throat pipe 1 length is 1 / 3, the ratio of the opening diameter to the throat pipe 1 diameter is 1 / 12, and the elastic valve disc 21 is a circular valve disc 21, whose area is twice that of the boost hole area, and whose thickness is 1 / 3 of the ejector tube thickness.
[0027] The implementation principle of this embodiment is: the valve plate 21 is in a closed state when operating under low flow conditions. It will automatically open when operating under high flow conditions and when the pressure in the ejector is close to the cavitation low pressure, and introduce the high-pressure liquid in the pump cavity into the low-pressure area of the ejector throat 1 to increase the pressure in this area, improve the anti-cavitation performance of the ejector of the jet centrifugal pump, and achieve the expected design effect.
[0028] The embodiments of this specific implementation method are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.
Claims
1. An ejector, characterized in that: The invention comprises a throat pipe (1), wherein a one-way valve (2) is arranged on the throat pipe (1), and the one-way valve (2) is unidirectionally conducted toward the throat pipe (1).
2. An ejector according to claim 1, characterized in that: The ratio of the distance from the location of the one-way valve (2) to the inlet of the throat pipe (1) to the length of the throat pipe (1) is 1 / 6 to 1 / 3.
3. An ejector according to claim 1, characterized in that: A mounting hole (11) is provided on the throat pipe (1). The one-way valve (2) comprises a valve plate (21). The valve plate (21) is mounted on the throat pipe (1). The valve plate (21) and the mounting hole (11) constitute the one-way valve (2).
4. An ejector according to claim 3, characterized in that: The ratio of the diameter of the mounting hole (11) to the diameter of the throat (1) is 1 / 12 to 1 / 15.
5. The ejector according to claim 1, characterized in that: The one-way valves (2) are multiple and are distributed in a circular pattern on the throat (1).
6. An ejector according to claim 3, characterized in that: The thickness of the valve plate (21) is 1 / 3 to 1 / 2 of the thickness of the ejector tube.
7. An ejector according to claim 3, characterized in that: The area of the valve plate (21) is 1.5 to 2 times the area of the mounting hole (11).
8. An ejector according to claim 3, characterized in that: The valve plate (21) is a cantilever beam type. The cross-sectional displacement of the valve plate (21) is: Wherein: q is the uniformly distributed load acting on the valve plate (21); a is the length of the stress-free valve plate (21); c is the length of the stressed valve plate (21); E represents the elastic modulus; and I is the moment of inertia of the section.
9. An ejector according to claim 3, characterized in that: Under the action of pressure, the flow rate through the valve plate (21) can be expressed as Where: C is the flow coefficient, δ max is the maximum deflection of the cantilever valve end, ρ is the fluid density, r is the characteristic length of the cantilever, and ΔP is the pressure difference at both ends of the cantilever.
10. A jet centrifugal pump, characterized in that: Comprising an ejector as described in any one of claims 1-9.