CN205744629U - A kind of ejector improving jet-type centrifugal pump cavitation performance - Google Patents

Abstract

This utility model relates to a kind of ejector improving jet-type centrifugal pump cavitation performance, including nozzle, Drainage Section, mixing section, trunnion, diffuser and pressurized hole.When jet-type centrifugal pump runs at big flow rate working conditions, pressurized hole is designed at ejector trunnion position, highly pressurised liquid in pump chamber is introduced trunnion area of low pressure by pressurized hole, increase the pressure of trunnion area of low pressure, suppression ejector trunnion is internal there is cavitation induced vibration, noise, improve ejector trunnion internal generation cavitation and cause jet-type centrifugal pump lift drastically to decline phenomenon, by lift snap point to big flow excursion, increase the range of operation of jet-type centrifugal pump.

Description

A kind of ejector improving jet-type centrifugal pump cavitation performance

Technical field

This utility model relates to the critical piece ejector of a kind of jet-type centrifugal pump, is related specifically to a kind of can improvement and penetrates The ejector of flow centrifugal pump cavitation performance.

Background technology

Jet-type centrifugal pump is a kind of electric pump using ejector and the design of centrifugal pump compound mode, and it is tight that it has structure Gather, easy to operate, restarting without pouring water, without installing bottom valve, the advantages such as self-priming can be realized, in gardens drip irrigation, agricultural spray The water-saving systems such as filling are widely used.Compared with conventional centrifugal pump, the operation logic of jet-type centrifugal pump: go out to flow to from pump stator The highly pressurised liquid entering pump chamber forms parital vacuum by injection stream at mixing section, makes the liquid in pump water inlet pipeline at atmospheric pressure The mixing section of ejector, and then the liquid mixing gone out with injection stream is entered by Drainage Section, jointly through trunnion, diffusion under effect Section flows into centrifugal impeller and discharges from stator, and wherein, a part of liquid discharges pump chamber, and another part liquid is then entered by ejector Mouth continues to flow into impeller, such circular flow with liquid mixing in inlet tube.Based on jet-type centrifugal pump operation principle special Property, find according to research, in running, jet-type centrifugal pump internal pressure extreme lower position produces in trunnion region, and this is just The cavitation determining such pump does not occurs at impeller inlet, and is to occur at a certain position of ejector trunnion.Along with flow Increase, cause jet-type centrifugal pump lift drastically to decline generation cavitation inside ejector trunnion, simultaneously induced vibration with Noise, limits its flow operating range.

Therefore, design is a kind of in big flow running, by the highly pressurised liquid in pump chamber is introduced ejector throat Region, in order to increase the pressure in this region, and then the ejector improving jet-type centrifugal pump cavitation performance is most important.

Summary of the invention

The purpose of this utility model is to provide a kind of ejector improving jet-type centrifugal pump cavitation performance, including spray Mouth, Drainage Section, mixing section, trunnion, diffuser and pressurized hole.A number of pressurized hole is offered at ejector trunnion position, will Highly pressurised liquid in pump chamber introduces ejector trunnion area of low pressure, in order to increase the pressure in this region, in suppression ejector trunnion There is cavitation induced vibration, noise in portion, improves ejector trunnion internal generation cavitation and cause jet-type centrifugal pump lift drastically Decline phenomenon, by lift snap point to big flow excursion, increase the flow operating range of jet-type centrifugal pump.

For achieving the above object, the following scheme of this utility model employing:

First according to design requirement, nozzle diameter is determined

$D_1=\sqrt{\frac{4Q_1}{3.14\mathrm{\μ}\sqrt{2g\mathrm{\α}\frac{{\mathrm{\Δp}}_0}{\mathrm{\γ}}}}}$

In formula: Q₁For nozzle injection flow, wherein, nozzle injection flow Q₁Equal to centrifugal impeller inlet flow rate Q₀Deduct pump Inlet flow rate Q₂, centrifugal impeller inlet flow rate Q₀With pump inlet flow Q₂Can draw according to jet-type centrifugal pump design requirement；

μ is solid particle and liquid velocity slip correction factor, and in water medium, its numerical value is 1；

α is ejector trunnion import function, and empirical value takes 1～1.05；

Δp₀For the pressure differential of nozzle inlet Yu Drainage Section import department, Drainage Section inlet pressure can be approximately at pump inlet Pressure；

γ is the unit weight of liquid.

And then determine:

Throat pipe diameter:Wherein, area ratio R represents the ratio of throat area and nozzle area, its value with Flow-rate ratio M is correlated with, and flow-rate ratio M represents centrifugal impeller inlet flow rate Q₀With nozzle injection flow Q₁Ratio；

Nozzle cylindrical outlet length: L₁=(0.3～0.5) D₁；

Larynx mouth is away from L₂=(0.5～1) D₂, the larynx mouth distance away from the length for mixing section, i.e. jet expansion to trunnion import；

Length of throat: L₃=(1.5～3) D₂；

Diffuser length: L₄=(2～5) D₂, wherein, L₄Being determined by diffusion angle beta, β takes 5 °～8 °.

In such scheme, pressurized hole is to trunnion import distance L₀With length of throat L₃Ratio be 1/6～1/2.

In such scheme, in pressurized hole, liquid goes out flow path direction and with trunnion to flow impact loss should be can reduce as far as possible Preferably, i.e. pressurized hole is θ with the direction of trunnion wall angle, 30 °≤θ≤90 °.

In such scheme, pressurized hole diameter D₀With throat pipe diameter D₂Ratio be 1/20～1/12.

In such scheme, pressurized hole number 2≤N≤4, and circumferencial direction is uniformly distributed.

The beneficial effects of the utility model are:

Using the ejector of this structure, can be effectively improved when big flow rate working conditions runs, ejector trunnion is internal to be occurred The vibration and noise of cavitation induction；When improving the operation of big flow rate working conditions, ejector trunnion is internal occurs cavitation to cause lift anxious Acute decline problem, by lift snap point to big flow excursion, increases the range of operation of jet-type centrifugal pump.

Accompanying drawing explanation

Fig. 1 is the jet-type centrifugal pump schematic diagram of existing two kinds of different jet device structures, figure (a) be ejector be straight tube-like Jet-type centrifugal pump, figure (b) is the jet-type centrifugal pump of ejector band bend pipe；

Fig. 2 is the ejector schematic diagram of existing two kinds of different structures, and figure (a) is the ejector in straight tube-like, and figure (b) is band The ejector of bend pipe；

Fig. 3 is the ejector schematic diagram of two kinds of different structures described in the utility model, and figure (a) is the jet in straight tube-like Device, figure (b) be that in figure (a), F-F is to the schematic diagram in cross section, and figure (c) is the ejector of band bend pipe, figure (d) for scheme in (c) F-F to The schematic diagram in cross section；

Fig. 4 is the ejector internal flow situation schematic diagram of two kinds of different structures described in the utility model.

Description of reference numerals:

1-inlet ductwork, 2-ejector, 21-nozzle, 22-Drainage Section, 23-mixing section, 24-trunnion, 25-diffuser, 26- Pressurized hole, 3-centrifugal impeller, 4-stator, 5-pump chamber, 6-export pipeline, 7-motor.

Detailed description of the invention

Fig. 3 show the structure of a kind of ejector 2 that can improve jet-type centrifugal pump cavitation performance described in the utility model Schematic diagram, the ejector 2 of described jet-type centrifugal pump, including nozzle 21, Drainage Section 22, mixing section 23, trunnion 24, diffuser 25 With pressurized hole 26.

As in figure 2 it is shown, when jet-type centrifugal pump runs at big flow rate working conditions, ejector trunnion is internal by generation cavitation Pump lift is caused drastically to decline, simultaneously induced vibration noise.As shown in Figure 4, when designing pressurized hole at ejector 2 trunnion 24 position After 26, the highly pressurised liquid in pump chamber 5 is introduced trunnion 24 area of low pressure by pressurized hole 26, increases the pressure of trunnion 24 area of low pressure, Improve the anti-cavitation performance of jet-type centrifugal pump ejector 2.Reach expected design effect.

As it is shown on figure 3, pressurized hole 26 and trunnion 24 wall angle theta are 30 °≤θ≤90 °, it is preferred that the trunnion of ejector 2 24 length L₃Time longer, pressurized hole 26 and trunnion 24 wall angle theta are 30 °≤θ≤60 °.Pressurized hole 26 to trunnion 24 import away from From L₀With trunnion 24 length L₃Ratio be 1/6～1/2.Pressurized hole 26 diameter D₀With trunnion 24 diameter D₂Ratio be 1/20～ 1/12.Pressurized hole 26 number is 2≤N≤4, and circumferencial direction is uniformly distributed.

Last it is noted that above example is only in order to illustrate the technical solution of the utility model, it is not intended to limit； The pressurized hole being wherein used for improving trunnion area of low pressure flow stream pressure is indispensable part in this programme, but does not enter it Row limits, as long as by the highly pressurised liquid introducing trunnion area of low pressure in pump chamber thus can play by pressurized hole described ejector To improving the scheme of cavitation performance all at the row of protection of the present utility model.Although with reference to foregoing embodiments to this utility model It is described in detail, it will be understood by those within the art that；It still can be to described in previous embodiment Technical scheme is modified, or wherein portion of techniques feature is carried out equivalent；And these amendments or replacement, do not make The essence of appropriate technical solution departs from the spirit and scope of this utility model each embodiment technical scheme.

Claims (6)

1. the ejector improving jet-type centrifugal pump cavitation performance, it is characterised in that include nozzle (21), Drainage Section (22), mixing section (23), trunnion (24), diffuser (25) and pressurized hole (26), described pressurized hole (26) is arranged at ejector (2) Trunnion (24) position, described pressurized hole (26) arrive trunnion import distance L₀With length of throat L₃Ratio be 1/6～1/2, supercharging Hole (26) is θ with the direction of trunnion (24) wall angle, 30 °≤θ≤90 °.

A kind of ejector improving jet-type centrifugal pump cavitation performance the most according to claim 1, it is characterised in that: described The diameter D of pressurized hole (26)₀Diameter D with trunnion (24)₂Ratio be 1/20～1/12.

A kind of ejector improving jet-type centrifugal pump cavitation performance the most according to claim 1, it is characterised in that: described The number of pressurized hole (26) is that N, 2≤N≤4, and circumferencial direction are uniformly distributed.

A kind of ejector improving jet-type centrifugal pump cavitation performance the most according to claim 1, it is characterised in that: described A diameter of D of nozzle (21)₁,

In formula:

Q₁For nozzle injection flow, wherein, nozzle injection flow Q₁Equal to centrifugal impeller inlet flow rate Q₀Deduct pump inlet flow Q₂, Centrifugal impeller inlet flow rate Q₀With pump inlet flow Q₂Can draw according to jet-type centrifugal pump design requirement；

μ is solid particle and liquid velocity slip correction factor, and in water medium, its numerical value is 1；

α is ejector trunnion import function, and empirical value takes 1～1.05；

Δp₀For the pressure differential of nozzle inlet Yu Drainage Section import department, Drainage Section inlet pressure can be approximately pressure at pump inlet；

γ is the unit weight of liquid.

A kind of ejector improving jet-type centrifugal pump cavitation performance the most according to claim 4, it is characterised in that: described A diameter of D of trunnion (24)₂:

Wherein, area ratio R represents the ratio of throat area and nozzle area, and its value is relevant to flow-rate ratio M, flow-rate ratio M represent from Lobus cardiacus wheel inlet flow rate Q₀With nozzle injection flow Q₁Ratio；

The a length of L of cylindrical outlet of nozzle (21)₁: L₁=(0.3～0.5) D₁。

A kind of ejector improving jet-type centrifugal pump cavitation performance the most according to claim 5, it is characterised in that: described The a length of larynx mouth of mixing section (23) away from, larynx mouth is away from L₂=(0.5～1) D₂, i.e. jet expansion is to the distance of trunnion import；

The a length of L of trunnion (24)₃: L₃=(1.5～3) D₂；

The a length of L of diffuser (25)₄: L₄=(2～5) D₂, wherein, L₄Being determined by diffusion angle beta, β takes 5 °～8 °.