CN102444612B - Design method for three-screw axial-flow pump impeller - Google Patents

Abstract

The invention provides a design method for a three-screw axial-flow pump impeller. Three screw blades can automatically balance un-balanced centrifugal inertia force when the impeller rotates, so that vibration and noise in the operating process of the pump can be reduced; the design method gives a design formula of main geometric parameters consisting of impeller inlet diameter D1, impeller hub diameter dh, impeller maximum outer diameter D2max, outlet side tilt angle alpha2, impeller minimum outer diameter D2min, outlet side width b2 and impeller axial length L, of the impeller. The impeller designed by the design method not only has no blockage, good anti-winding performance, good balance effect, but also improves the restriction capacity of the axial-flow pump blade to the medium, thus, under the same flow rate, the impeller has a lift higher than that of single-screw, double-screw blade axial-flow pump. Therefore, the screw axial-flow pump employing the impeller is in particular suitable for wastewater treatment industry.

Description

Triple helical 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 triple helical 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.Because its structural feature of axial-flow pump of single-screw blade has determined the nonsymmetry of its shape, its non-uniform mass.When wheel rotation, just produce unbalanced centrifugal inertia force, thereby make the pump housing produce vibration and noise, the not stationarity when having increased pump operation.The impeller that this just requires us to design can improve mobility status, and good static balancing effect is arranged again.

Summary of the invention

For solving the deficiency of existing axial-flow pump impeller performance, the invention provides a kind of triple helical 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.Impeller with the present invention's design does not only have obstruction, antiwind performance is good, has good counterbalance effect, has improved the restriction ability of axial flow pump blade inner to medium again simultaneously, under same traffic, and more single, double helical blade axial flow lift of pump height.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 $D_{}$ ${}_1=K_0\sqrt[5]{Q/\mathrm{<figure-callout\; id="5"\; label="n"\; filenames="HSA00000618999100011.png"\; state="\{\{state\}\}">n</figure-callout>}};$

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: ${\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HSA00000618999100011.png"\; state="\{\{state\}\}">D</figure-callout>}}_{2\max }=K_1{\left(\frac{n_s}{100}\right)}^{-0.4}\sqrt[3]{Q/\mathrm{<figure-callout\; id="3"\; label="n"\; filenames="HSA00000618999100011.png"\; state="\{\{state\}\}">n</figure-callout>}};$

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

K ₁-correction factor, K ₁=(2.5～5);

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;

The n-wheel speed, rev/min;

n _s-specific speed.

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=100 °～300 °.

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 °～15 °, specific speed gets the small value greatly, and the number of blade many persons get the small value.

The invention has the beneficial effects as follows: can improve the impeller counterbalance effect, improve lift of pump.

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

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, impeller inlet is the spiral protrusive type, and inlet side (13) looks that just as the reaping hook shape blade (3) rises along wheel hub (4) spiral, and its blade (3) number Z is less than 3, and blade (3) number too much can influence the conveyance capacity of impeller.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).

${\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="HSA00000618999100011.png"\; state="\{\{state\}\}">D</figure-callout>}}_1=K_0\sqrt[5]{Q/\mathrm{<figure-callout\; id="5"\; label="n"\; filenames="HSA00000618999100011.png"\; state="\{\{state\}\}">n</figure-callout>}};$

d _h＝19.65+0.071n _s；

${\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HSA00000618999100011.png"\; state="\{\{state\}\}">D</figure-callout>}}_{2\max }=K_1{\left(\frac{n_s}{100}\right)}^{-0.4}\sqrt[3]{Q/\mathrm{<figure-callout\; id="3"\; label="n"\; filenames="HSA00000618999100011.png"\; state="\{\{state\}\}">n</figure-callout>}};$

${\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HSA00000618999100011.png"\; state="\{\{state\}\}">b</figure-callout>}}_2={\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="HSA00000618999100011.png"\; state="\{\{state\}\}">K</figure-callout>}}_2\sqrt{2\mathrm{gH}}/n;$

L＝(0.9～1.05)D _2max；

φ＝100°～300°；

α ₂＝40°～70°；

D _2min＝D _2max-b ₂tanα ₂；

β ₂＝5°～15°。

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=100 °～300 °.

Claims (1)

1. a triple helical 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:

$D_1=K_0\sqrt[3]{Q/n};$

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°～15°；

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=(2.5～5);

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

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