CN102400946B - Method for designing single-screw axial-flow pump impeller - Google Patents

Abstract

The invention provides a method for designing a single-screw axial-flow pump impeller. The method provides a design formula of the main geometric parameters of the impeller such as the diameter D1 of an impeller inlet, the diameter dh of an impeller hub, the maximum outer diameter D2max of the impeller, the inclined angle alpha2 of an outlet edge, the minimum outer diameter D2min of the impeller, the width b2 of the outlet edge and the axial length L of the impeller. By application of the impeller designed by the invention, not only is need for sewage treatment met, but also the flowing condition is improved simultaneously, and the flowing capability, no destruction and no winding of an axial flow pump are improved. Therefore, the single-screw axial-flow pump applying the impeller is especially suitable for the sewage treatment industry.

Description

Single-screw axial-flow pump impeller design method

Technical field

The present invention relates to a kind of design method of axial-flow pump impeller, particularly a kind of single-screw axial-flow pump impeller design method.

Background technique

At present, what known axial-flow pump impeller adopted is airfoil fan, namely adopts lift method and streamline method design axial flow pump blade inner.With the airfoil fan of this two kinds of design method design, strict requirement has been proposed all for working environment and the laying of blade of axial-flow pump.Namely can only be for delivery of clear water or slight sewage, as use the blowdown pumping plant, the water quality complexity, silt is many, foreign material are many, cause impeller blade to twine foreign material easily, stop up, cause outer end mechanical seal distortion, cause mechanical seal to be lost efficacy, the motor water inlet, pump is frequently reported to the police, increase maintenance frequency, even burn out motor; And if its blade angle can cause operational shock inconsistent, and the cavitation performance of while pump is variation also.Thereby, adopt the axial-flow pump of airfoil fan can not satisfy the condition of under complex environment, moving.

Do not take place to twine and stop up for axial-flow pump can be moved under the operating mode of complexity, need to adopt the screw type blade, and for guaranteeing its conveyance capacity, the number of blade can not be too much.The impeller that this just requires us to design can improve mobility status, is unlikely to influence axial flow lift of pump and efficient again.

Summary of the invention

For solving the deficiency of existing axial-flow pump impeller performance, the invention provides a kind of single-screw axial-flow pump impeller design method.Utilize following relation to determine the main geometric parameters of impeller, mainly comprise: inlet diameter D ₁, the impeller hub diameter d _h, impeller maximum outside diameter D _2max, outlet limit inclined angle alpha ₂, impeller minimum outer diameter D _2min, outlet hem width degree b ₂With the impeller axial length L.Not only satisfy the needs of sewage treatment with the impeller of the present invention design, improved mobility status simultaneously, improved the conveyance capacity of axial-flow pump and non-destructive, no winding performance.Therefore, the spiral axial-flow pump of using this kind impeller is particularly suitable for sewage treatment industry.Realize that above-mentioned purpose adopts technological scheme:

1, the inlet diameter D of impeller ₁

Its formula $D_{}$ ${}_1=K_0\sqrt[5]{Q/n};$

In the formula: D ₁-impeller inlet diameter, rice;

The flow of Q-design conditions, cube meter per second;

The n-wheel speed, rev/min;

K ₀-correction factor, K ₀Big value is got to suction performance is demanding in=(1～2.5).

2, hub diameter d _h

Its formula: d _h=19.65+0.071n _s

In the formula: d _h-impeller hub diameter, rice;

n _s-specific speed.

3, impeller maximum outside diameter D _2max

Its formula: ${\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HSA00000618966100011.png"\; state="\{\{state\}\}">D</figure-callout>}}_{2\max }=K_1{\left(\frac{n_s}{100}\right)}^{-0.4}\sqrt[3]{Q/\mathrm{<figure-callout\; id="3"\; label="n"\; filenames="HSA00000618966100011.png"\; state="\{\{state\}\}">n</figure-callout>}};$

In the formula: D _2max-impeller maximum outside diameter, rice;

K ₁-correction factor, K ₁=(5～7.5);

n _s-specific speed;

The flow of Q-design conditions, cube meter per second;

The n-wheel speed, rev/min.

4, impeller outlet width b ₂

Its formula: $b_2=K_2\sqrt{2\mathrm{gH}}/n;$

In the formula: b ₂-impeller outlet width, rice;

K ₂-correction factor, K ₂=(0.024～0.032) n _s

H-design conditions point lift, rice;

n _s-specific speed;

The n-wheel speed, rev/min.

5, impeller axial length L

Its formula: L=(0.9～1.05) D _2max

In the formula: L-impeller axial length, rice;

D _2max-impeller maximum outside diameter, rice.

6, impeller cornerite φ

Impeller cornerite φ=200 °～500 °, 400 ° commonly used.

7, outlet limit inclined angle alpha ₂

Outlet limit inclined angle alpha ₂=40 °～70 °.

8, impeller minimum outer diameter D _2min

Its formula: D _2min=D _2max-b ₂Tan α ₂

In the formula: D _2min-impeller minimum outer diameter, rice;

D _2max-impeller maximum outside diameter, rice;

b ₂-impeller outlet width, rice;

α ₂-outlet tilt angle, limit, degree.

9, blade exit laying angle β ₂

Blade exit laying angle β ₂=5 °～25 °, specific speed gets the small value greatly.

The invention has the beneficial effects as follows: impeller can improve mobility status, improves its conveyance capacity and does not have winding, non-destructive.

The present invention is on probation through the user, and reaction effect is good.

Description of drawings

Fig. 1 is the impeller axial plane figure of one embodiment of the invention.

Fig. 2 is same embodiment's impeller blade planimetric map.

Fig. 3 is same embodiment's impeller design sketch.

Among Fig. 1: 1. impeller inlet diameter D ₁, 2. hub diameter d _h, 3. helical blade, 4. wheel hub, 5. axis hole, 6. impeller maximum outside diameter D _2max, 7. export the limit inclined angle alpha ₂, 8. export hem width degree b ₂, 9. impeller axial length L, 10. impeller minimum outer diameter D _2min

Among Fig. 2: 4. wheel hub, 11. impeller outlet laying angle β ₂, 12. subtended angle of blade φ, 13. impeller inlet limits, 14. impeller outlet limits.

Embodiment

Fig. 1, Fig. 2 and Fig. 3 have determined this embodiment's impeller shape jointly.It and common axial-flow pump impeller are different, and impeller inlet is the spiral protrusive type, and inlet side (13) looks just as the reaping hook shape, blade (3) rises along wheel hub (4) spiral, and its blade (3) number has only one, thereby possesses very big runner, has good performance and the non-destructive of passing through.The present invention determines impeller inlet diameter D by following relation ₁(1), impeller hub diameter d _h(2), impeller maximum outside diameter D _2max(6), outlet limit inclined angle alpha ₂(7), outlet hem width degree b ₂(8), impeller axial length L (9) and impeller minimum outer diameter D _2min(10).

${\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="HSA00000618966100011.png"\; state="\{\{state\}\}">D</figure-callout>}}_1=K_0\sqrt[5]{Q/n};$

d _h＝19.65+0.071n _s；

${\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HSA00000618966100011.png"\; state="\{\{state\}\}">D</figure-callout>}}_{2\max }=K_1{\left(\frac{n_s}{100}\right)}^{-0.4}\sqrt[3]{Q/\mathrm{<figure-callout\; id="3"\; label="n"\; filenames="HSA00000618966100011.png"\; state="\{\{state\}\}">n</figure-callout>}};$

${\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HSA00000618966100011.png"\; state="\{\{state\}\}">b</figure-callout>}}_2={\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="HSA00000618966100011.png"\; state="\{\{state\}\}">K</figure-callout>}}_2\sqrt{2\mathrm{gH}}/n;$

L＝(0.9～1.05)D _2max；

φ＝200°～500°；

α ₂＝40°～70°；

D _2min＝D _2max-b ₂tanα ₂

β ₂＝5°～25°。

In the drawings, blade exit laying angle (11) chooses and specific speed n _sSize relevant, specific speed is big, the outlet laying angle (11) get the small value.Subtended angle of blade is according to casting and the difficulty or ease situation of sand removal, chooses between φ=200 °～500 °.

Claims (1)

1. a single-screw axial-flow pump impeller design method provides impeller main geometric parameters inlet diameter D ₁, hub diameter d _h, maximum outside diameter D _2max, outlet limit inclined angle alpha ₂, minimum outer diameter D _2minWith outlet hem width degree b ₂Design formula; It is characterized in that: be fit to following relation between impeller geometric parameter and the pump design conditions point performance parameter:

$D_1=K_0\sqrt[5]{Q/n};$

d _h＝19.65+0.071n _s；

$D_{2\max }=K_1{\left(\frac{n_s}{100}\right)}^{-0.4}\sqrt[3]{Q/n};$

$b_2=K_2\sqrt{2\mathrm{gH}}/n;$

D _2min＝D _2max-b ₂tanα ₂

α ₂＝40°～70°；

β ₂＝5°～25°；

In the formula: D ₁-impeller inlet diameter, rice; The flow of Q-design conditions, cube meter per second;

The n-wheel speed, rev/min; d _h-impeller hub diameter, rice; n _s-specific speed;

D _2max-impeller maximum outside diameter, rice; b ₂-impeller blade exit width, rice;

H-design conditions point lift, rice; D _2min-impeller minimum outer diameter, rice;

α ₂-exit edge of blade tilt angle, degree; β ₂-impeller blade outlet laying angle, degree;

K ₀-correction factor, K ₀=(1～2.5); K ₁-correction factor, K ₁=(5～7.5);

K ₂-correction factor, K ₂=(0.024～0.032) n _s

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