CN103671237A - Efficient layering-type centrifugal pump blade waterpower design method - Google Patents

Abstract

The invention provides an efficient layering-type centrifugal pump blade waterpower design method. One blade of a traditional centrifugal pump is segmented into more than two layers, small blades close to a blade outlet layer are encrypted, it is guaranteed that the number of blades on the Nth layer is greater than that of blades on the N-1th layer, the phenomena of flow slide, backflow and the like of fluid on a blade outlet can be effectively reduced or eliminated, and centrifugal pump blade waterpower efficiency is further improved. By determining the relationship among the number Z1 of blades on the first layer, the number ZN of blades on the Nth layer, the Nth layer of blade inlet setting angles and the N-1th layer of blade outlet setting angles, waterpower design of multiple layers of blades is completed. The efficient layering-type centrifugal pump blade waterpower design method has the advantages that the phenomena of flow slide, backflow and the like of the fluid on the centrifugal pump blade outlet can be effectively reduced or eliminated, and the purpose of improving efficiency of the centrifugal pump is achieved.

Description

A kind of layer-stepping efficient centrifugal pump blade Hydraulic Design Method

Technical field

The present invention relates to centrifugal pump the Hydraulic Design field, particularly a kind of layer-stepping efficient centrifugal pump blade Hydraulic Design Method.

Background technique

Centrifugal pump is a kind of for fluid provides the workalike product of energy, relates to field very extensive.Blade is centrifugal pump " heart ", directly affect centrifugal pump performance, at present, set up a collection of outstanding blade hydraulic model, obtained certain achievement in research, conventional centrifugal pump design method mainly contains velocity coefficient method, scale model scaling method, enlargement discharge method etc., these design method all design for an intact leaf, because the circumferential length of entrance edge of blade will be far smaller than exit edge of blade circumferential length, and be subject to the impact of inlet vane excretion coefficient, the number of blade should not be got too much, general 2-7 sheet left and right, will make like this blade exit place there will be the fluid slippage of flowing, fluid comes off, the phenomenons such as backflow, and then affect centrifugal blade efficiency.

Summary of the invention

The object of the invention is for solving the mobile slippage of existing centrifugal blade outlet port fluid, the phenomenons such as backflow and the problem that improves the aspects such as efficiency of centrifugal pump, design a kind of layer-stepping efficient centrifugal pump blade Hydraulic Design Method, blade of conventional centrifugal pump is divided into N(N and is more than or equal to 2) layer, carry out hierarchical design, and to being encrypted near blade exit layer small leaf, guarantee that the N layer number of blade is more than or equal to the first layer number of blade, and then can effectively reduce, eliminate the mobile slippage of blade exit place fluid, the phenomenons such as backflow, further improve centrifugal blade hydraulic efficiency.

The present invention utilizes following key parameter, mainly comprises: first layer blade inlet diameter

first layer blade exit diameter

first layer blade is imported and exported laying angle

with n layer blade inlet diameter

n layer blade exit diameter

n layer blade imported and exported laying angle with blade exit width b ₂deng.

Further, first according to Centrifugal Pump Design flow Q, lift H, the performance parameters such as rotating speed are determined the appearance profile physical dimension of centrifugal pump, i.e. first layer blade inlet diameter

with N layer blade exit diameter first layer blade import laying angle

with N layer blade exit laying angle

blade exit width b ₂.

1. first layer blade inlet diameter

$D_1^1=k_1\sqrt[3]{\frac{Q}{n}}$

In formula, k ₁-coefficient, gets 3-6

N-design speed

2. N layer blade exit diameter

$D_2^N=k_2\sqrt[3]{\frac{Q}{n}}$

In formula, ${\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="1312271716481.png"\; state="\{\{state\}\}">k</figure-callout>}}_2=9.35k_{D2}{\left(\frac{n_s}{100}\right)}^{-0.5}$

K _d2-be correction factor, get 1.0～1.18

N _s-specific speed, $n_s=\frac{3.65n\sqrt{Q}}{H^{3/4}}$

3. blade exit width b ₂

${\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="1312271716481.png"\; state="\{\{state\}\}">b</figure-callout>}}_2=k_b\sqrt[3]{\frac{Q}{n}}$

In formula, $k_b=0.64k_{b2}{\left(\frac{n_s}{100}\right)}^{5/6}$

K _b2-correction factor, gets 1.0～2.0

4. first layer blade import laying angle

Get ${\mathrm{\&beta;}}_1^1={\mathrm{\&beta;}}_1^{\&prime;}+\mathrm{\&Delta;\&beta;}$

In formula, Δ β is the import liquid stream angle of attack, generally gets 3 °-15 °;

wherein, v _m1for the flow rate on axial surface of liquid, q is Centrifugal Pump Design flow, η _vfor volumetric efficiency, F ₁first layer discharge section area,

for first layer import excretion coefficient; u ₁peripheral velocity for liquid; v _u1for the peripheral compoent of velocity of liquid, to straight-tapered suction chamber v _u1=0.

5. N layer blade exit laying angle

Get

be 9 °～45 °, what subtended angle of blade was large gets the small value.

Secondly, by blade layering.From 1-5 relation can be fixed the appearance profile physical dimension of blade, blade is divided into N layer, n layer blade exit diameter wherein

the outlet diameter that is described N layer blade is 0.5～1 times of N-1 layer blade exit diameter.

6. first layer number of blade Z ₁

$Z_1=K\frac{D_{m1}}{e_1}\sin {\mathrm{\&beta;}}_{m1},$ Result of calculation rounds.

In formula, K is empirical, when impeller is general cast member, gets 6.5; e ₁length of run for center line in first layer impeller channel axis plane projection;

${\mathrm{\&beta;}}_{m1}=\frac{1}{2}({\mathrm{\&beta;}}_1+{\mathrm{\&beta;}}_2^1).$

7. N layer number of blade Z _n

General satisfaction Z _n>=Z _n-1>=...>=Z ₁, special Z _n=2Z _n-1=...=2 ^n-1z ₁or Z _n=3Z _n-1=...=3 ^n-1z ₁deng.

8. n layer blade import laying angle

${\mathrm{\&beta;}}_1^N={\mathrm{\&beta;}}_1^{N^{\&prime;}}+{\mathrm{\&Delta;\&beta;}}_1^N;{\mathrm{\&beta;}}_1^{N^{\&prime;}}=\arctan \frac{v_{1m}^N}{v_{\mathrm{uN}}},$

be that N layer import liquid flows the angle of attack, generally get to be less than or equal to ± 5 °.

In formula, N layer axial plane inlet velocity

f _nn layer discharge section area, it is N layer import excretion coefficient; v _uNit is N layer import peripheral velocity.

9. N-1 layer blade exit laying angle

with N layer blade import laying angle

relation

${\mathrm{\&beta;}}_2^{N-1}={\mathrm{\&beta;}}_1^N+{\mathrm{\&Delta;\&beta;}}_1^N.$

The beneficial effect of layer-stepping efficient centrifugal pump blade Hydraulic Design Method of the present invention is: can effectively reduce and eliminate the phenomenons such as the mobile slippage of centrifugal blade outlet port fluid, backflow, compare with traditional design method, can effectively improve the hydraulic efficiency of centrifugal pump 2-8 percentage point.

Accompanying drawing explanation

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

Fig. 2 is the half-open impeller axial plane figure of one embodiment of the present of invention.

Fig. 3 is the location map of layering blade.

In figure, the implication of mark is as follows: 1-front shroud of impeller, 2-back shroud of impeller, 3-impeller, 4-first layer blade, the 5-the N layer blade, 6-half-opened impeller.

Embodiment

As Figure 1-3, jointly having determined the blade shape of the embodiment of the present invention, is double shrouded wheel, as shown in Figure 1, or be half-open impeller, as shown in Figure 2, when half-open by front shroud 1(without front shroud), back shroud 2, first layer blade 4 to N layer blade 5 parts such as grade form.The present invention utilizes following relation to determine the main geometric parameters of impeller, comprising: first layer blade inlet diameter

first layer blade exit diameter

first layer blade is imported and exported laying angle

with

n layer blade inlet diameter

n layer blade exit diameter n layer blade imported and exported laying angle

with

blade exit width b ₂deng.

Further, first according to Centrifugal Pump Design flow Q, lift H, the performance parameters such as rotation speed n are determined the appearance profile physical dimension of centrifugal pump, i.e. first layer blade inlet diameter

with N layer blade exit diameter

first layer blade import laying angle

with N layer blade exit laying angle

blade exit width b ₂.

1. first layer blade inlet diameter

$D_1^1=k_1\sqrt[3]{\frac{Q}{n}}$

In formula, k ₁-coefficient, gets 3-6

N-design speed

2. N layer blade exit diameter

$D_2^N=k_2\sqrt[3]{\frac{Q}{n}}$

In formula, ${\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="1312271716481.png"\; state="\{\{state\}\}">k</figure-callout>}}_2=9.35k_{D2}{\left(\frac{n_s}{100}\right)}^{-0.5}$

K _d2-be correction factor, get 1.0～1.18

N _s-specific speed, $n_s=\frac{3.65n\sqrt{Q}}{H^{3/4}}$

3. blade exit width b ₂

${\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="1312271716481.png"\; state="\{\{state\}\}">b</figure-callout>}}_2=k_b\sqrt[3]{\frac{Q}{n}}$

In formula, $k_b={0.64k}_{b2}{\left(\frac{n_s}{100}\right)}^{5/6}$

K _b2-correction factor, gets 1.0～2.0

4. first layer blade import laying angle

Get ${\mathrm{\&beta;}}_1^1={\mathrm{\&beta;}}_1^{\&prime;}+\mathrm{\&Delta;\&beta;}$

In formula, Δ β is the import liquid stream angle of attack, generally gets 3 °-15 °;

wherein, v _m1for the flow rate on axial surface of liquid,

q is Centrifugal Pump Design flow, η _vfor volumetric efficiency, F ₁first layer discharge section area,

for first layer import excretion coefficient; u ₁peripheral velocity for liquid; v _u1for the peripheral compoent of velocity of liquid, to straight-tapered suction chamber v _u1=0.

5. N layer blade exit laying angle

Get

be 9 °～45 °, what subtended angle of blade was large gets the small value.

Secondly, by blade layering.From 1-5 relation can be fixed the appearance profile physical dimension of blade, blade is divided into N layer, n layer blade exit diameter wherein

the outlet diameter that is described N layer blade is 0.5～1 times of N-1 layer blade exit diameter.

6. first layer number of blade Z ₁

$Z_1=K\frac{D_{m1}}{e_1}\sin {\mathrm{\&beta;}}_1,$ Result of calculation rounds.

In formula, K is empirical, when impeller is general cast member, gets 6.5; e ₁length of run for center line in first layer impeller channel axis plane projection;

${\mathrm{\&beta;}}_{m1}=\frac{1}{2}({\mathrm{\&beta;}}_1+{\mathrm{\&beta;}}_2^1).$

7. N layer number of blade Z _n

General satisfaction Z _n>=Z _n-1>=...>=Z ₁, special Z _n=2Z _n-1=...=2 ^n-1z ₁or Z _n=3Z _n-1=...=3 ^n-1z ₁deng.

8. N layer blade import laying angle

${\mathrm{\&beta;}}_1^N={\mathrm{\&beta;}}_1^{N^{\&prime;}}+{\mathrm{\&Delta;\&beta;}}_1^N;{\mathrm{\&beta;}}_1^{N^{\&prime;}}=\arctan \frac{v_{1m}^N}{v_{\mathrm{uN}}},$

be that N layer import liquid flows the angle of attack, generally get to be less than or equal to ± 5 °.

In formula, N layer axial plane inlet velocity f _nn layer discharge section area,

it is N layer import excretion coefficient; v _uNit is N layer import peripheral velocity.

9. N-1 layer blade exit laying angle with N layer blade import laying angle

relation

${\mathrm{\&beta;}}_2^{N-1}={\mathrm{\&beta;}}_1^N+{\mathrm{\&Delta;\&beta;}}_1^N.$

Embodiment one

Described impeller outer profile form as shown in Figure 1, the impeller 3 that meets above-mentioned relation formula is enclosed blade shape, by blade is carried out to hierarchical design, can effectively reduce and eliminate the centrifugal blade outlet port fluid phenomenons such as slippage, backflow that flow, because the selection of first layer to the N layer number of blade should meet the requirement of relation 6 and relation 7.

Described first layer blade 4 is twisted blade, the 2nd to N-1 layer blade can be prismatic blade, can be also twisted blade, described N layer blade 5 is prismatic blade.

Embodiment two

Described impeller 3 forms can for semi-open type structural type as shown in Figure 2.

The first to N described layer blade 4 is twisted blade.

Claims (9)

1. a layer-stepping efficient centrifugal pump blade Hydraulic Design Method, is characterized in that a blade of centrifugal pump impeller to be divided into N layer, and N is more than or equal to 2; First layer blade inlet diameter

first layer blade exit diameter

first layer blade is imported and exported laying angle

with

n layer blade inlet diameter

n layer blade exit diameter n layer blade imported and exported laying angle

with

blade exit width b ₂, relation is as follows:

The first layer number of blade

result of calculation rounds;

In formula, K is empirical; e ₁length of run for center line in first layer blade passage axis plane projection; $D_{m1}=\frac{1}{2}(D_1+D_2^1);{\mathrm{\&beta;}}_{m1}=\frac{1}{2}({\mathrm{\&beta;}}_1+{\mathrm{\&beta;}}_2^1);$

N layer number of blade Z _nmeet Z _n>=Z _n-1>=...>=Z ₁;

N layer blade import laying angle ${\mathrm{\&beta;}}_1^N={\mathrm{\&beta;}}_1^{N^{\&prime;}}+{\mathrm{\&Delta;\&beta;}}_1^N;{\mathrm{\&beta;}}_1^{N^{\&prime;}}=\arctan \frac{v_{1m}^N}{v_{\mathrm{uN}}},$

it is the N layer import liquid stream angle of attack;

In formula, N layer axial plane inlet velocity

f _nbe N layer discharge section area, it is N layer import excretion coefficient; v _uNit is N layer import peripheral velocity;

N-1 layer blade exit laying angle

with N layer blade import laying angle pass is ${\mathrm{\&beta;}}_2^{N-1}={\mathrm{\&beta;}}_1^N+{\mathrm{\&Delta;\&beta;}}_1^N.$

2. layer-stepping efficient centrifugal pump blade Hydraulic Design Method as claimed in claim 1, is characterized in that: blade is prismatic blade or twisted blade.

3. layer-stepping efficient centrifugal pump blade Hydraulic Design Method as claimed in claim 1, is characterized in that: impeller form is double shrouded wheel or half-open impeller.

4. layer-stepping efficient centrifugal pump blade Hydraulic Design Method as claimed in claim 1, is characterized in that: the described N layer number of blade or Z _n=3Z _n-1=...=3 ^n-1z ₁.

5. layer-stepping efficient centrifugal pump blade Hydraulic Design Method as claimed in claim 1, is characterized in that: first layer import laying angle

In formula, Δ β is the import liquid stream angle of attack, gets 3 °-15 °;

wherein, v _m1for the flow rate on axial surface of liquid, q is Centrifugal Pump Design flow, η _vfor volumetric efficiency, F ₁for first layer discharge section area,

for first layer import excretion coefficient; u ₁peripheral velocity for liquid; v _u1the peripheral compoent of velocity for liquid.

6. layer-stepping efficient centrifugal pump blade Hydraulic Design Method as claimed in claim 1, is characterized in that: N layer outlet laying angle be 9 °～45 °, what subtended angle of blade was large gets the small value.

7. layer-stepping efficient centrifugal pump blade Hydraulic Design Method as claimed in claim 1, is characterized in that: the outlet diameter of described N layer blade is 0.5～1 times of N-1 layer blade exit diameter.

8. layer-stepping efficient centrifugal pump blade Hydraulic Design Method as claimed in claim 1, is characterized in that: when impeller is general cast member, K gets 6.5.

9. layer-stepping efficient centrifugal pump blade Hydraulic Design Method as claimed in claim 5, is characterized in that: the peripheral compoent of velocity v of the liquid of straight-tapered suction chamber _u1=0.

Images