CN104895832A - Hydraulic design method for high-viscosity centrifugal pump impeller - Google Patents

Abstract

The invention relates to a hydraulic design method for a high-viscosity centrifugal pump impeller. According to the physical characteristics of high-viscosity fluids, the flow area of a flow channel is properly enlarged, and the high-viscosity centrifugal pump impeller is hydraulically designed according to theoretical knowledge of fluid mechanics and past excellent hydraulic model design characteristics by a velocity coefficient method, and has high efficiency and fine non-blocking performance. Main design parameters of the hydraulic design method for the high-viscosity centrifugal pump impeller mainly include an impeller inlet diameter D1, an impeller hub diameter dh, a blade inlet laying angle beta1, a blade outlet laying angle beta2, an impeller outlet diameter D2, a blade outlet width b2, the number z of blades, a blade wrapping angle phi and the like. The high-viscosity centrifugal pump impeller has the advantages of working stability, high efficiency, fine non-blocking performance and wider applicable range.

Description

A kind of Hydraulic Design Method of high viscosity centrifugal pump impeller

Technical field

The present invention relates to a kind of Hydraulic Design Method of high viscosity centrifugal pump, be mainly used in using as transfer of highly viscous liquid in industry, also can be used for the slurry of the industry transmission such as electric power, metallurgy, coal containing solid particle, and ensure its high efficiency and good nonblocking performance.

Background technique

High-viscosity pump is mainly used in the conveying of industrial production medium-high viscosity liquid, and domestic demand is huge, and the structural design of industrial medium-high viscosity pump many employings gear pump and volute pump, this high-viscosity pump efficiency is low, flow is little, and pulsation is large, the shortcomings such as noise is large.And the invention of high viscosity centrifugal pump solves the deficiency of traditional high-viscosity pump, there is flow large and adjustable, the features such as efficiency is high, stable working.Impeller is the main flow passage components of high viscosity centrifugal pump, the direct performance characteristics affecting high viscosity centrifugal pump, traditional centrifugal pump Hydraulic Design Method has velocity-coefficient method, scale model scaling method, increasing discharge method etc., mainly carry out Similar improvement according to some outstanding hydraulic models, be not optimized from the design of theoretic to pump.The present invention considers the physical property of high viscosity fluid, the area of passage of suitable increasing runner, adopt velocity-coefficient method the knowwhy of integrated fluid mechanics and in the past outstanding hydraulic model design feature carry out the Hydraulic Design to high viscosity centrifugal pump impeller, make it have higher efficiency and good nonblocking performance.

Summary of the invention

Object of the present invention is providing in corresponding designing requirement parameter (flow Q, lift H etc.) situation, design one and have greater efficiency and good nonblocking performance high viscosity centrifugal pump, the invention provides and be a kind ofly applicable to the Hydraulic Design Method that hydrodynamic range of viscosities is the centrifugal pump impeller of 0.01 ~ 100mPas.

Realize above-mentioned purpose, the design method of employing is as follows:

1). impeller outlet diameter is designed:

$D_2=154.39{n_s}^{-0.606}.\sqrt[3]{\frac{Q}{n}};40\≤n_s\≤130;$

$D_2=(0.0187{n_s}^{0.5}+88.97{n_s}^{-0.5})\&CenterDot;\sqrt[3]{\frac{Q}{n}};130<n_s<300;$

D ₂₁＝(1.35～1.55)·D ₂

2). impeller inlet diameter is designed:

D ₁＝0.04087n _s ^0.5353·D ₂₁

3). impeller outlet hem width degree is designed:

$\mathrm{\&mu;}=\frac{\mathrm{\&tau;}}{du/dy}$

$b_2=0.1035{n_s}^{0.4223}.\sqrt[3]{\frac{Q}{n}};$

b ₂₁＝k ₀b ₂＝(1.5～1.8)b ₂；

4). impeller blade cornerite is designed:

5). according to the number of blade that the selection of specific speed of pump is suitable:

$\left\{\begin{array}{cc}z=5~7,& 40\&le;n_s<90\\ z=4~5,& 90\&le;n_s<210\\ z=3,& 210\&le;n_s<300\end{array}\right\}$

In formula:

D ₂-impeller outlet diameter, mm;

D ₂₁-high viscosity centrifugal pump impeller outlet diameter, mm;

N _s-high viscosity centrifugal pump specific speed;

Q-pump duty, m ³/ h;

N-revolution speed;

D ₁-impeller inlet diameter, mm;

μ-kinetic viscosity, mPas;

B ₂-Ordinary Centrifugal Pumps blade exit width, mm;

B ₂₁-high viscosity centrifugal blade exit width, mm;

-impeller blade cornerite, °;

Z-impeller blade number;

6). impeller outlet diameter is followed proportional, research finds when pump specific angular speed is 130, its Proportional coefficient K _dminimum, there is its scaling factor relation in therefore different specific speed range intervals, by the Proportional coefficient K in high viscosity Excellent Hydraulic Model Database of Centrifugal Pump outstanding in a large number and design experiences determination different specific speed interval _d.

7). according to the inlet diameter of outlet diameter determination pump, finding by studying high viscosity Excellent Hydraulic Model Database of Centrifugal Pump outstanding in a large number, under a certain specific speed, importing and exporting the ratio of diameter there is optimum interval, there is exponential relationship ε=0.04087n in ratio ε optimum value and specific speed _s ^0.5353, can the inlet diameter of the better more determination pump of system by impeller outlet diameter.

8). Hydraulic Design Method according to claim 1, is characterized in that: impeller outlet width and be directly proportional, according to a large amount of outstanding high viscosity Excellent Hydraulic Model Database of Centrifugal Pump databases, set up exit width COEFFICIENT K _bmathematical model, and adopt multiple target hydraulic design optimization method for its efficiency and cavitation performance 2, set up mathematical model modified, matching K _boptimum formula.

9). adopt double shrouded wheel structure, as specific speed n _swhen≤130, impeller blade import laying angle β ₁get 15 ° ~ 26 °, impeller blade outlet laying angle β ₂get 12 ° ~ 21 °, as specific speed n _sduring > 130, impeller blade import laying angle β ₁get 22 ° ~ 34 °, impeller blade outlet laying angle β ₂get 18 ° ~ 30 °, when design discharge, blade incidence Δ β adopts high incidence, and Δ β gets 3 ° ~ 5 °.

10). the design of subtended angle of blade is derived from mathematical model aspect, and the formula to cornerite is modified according to fluid mechanics knowledge and design experiences, when for there being the high viscosity centrifugal pump of particular/special requirement can increase cornerite to meet design requirement.

11). along with the increase of pump specific angular speed, number of blade z trends towards getting smaller value, and entrance edge of blade suitably protracts to suction port.

Accompanying drawing explanation

Fig. 1 is the axis projection of the impeller of one embodiment of the invention

Fig. 2 is the blade wheel structure sketch of one embodiment of the invention

In figure: 1. impeller inlet diameter D ₁, 2. impeller hub diameter d _h, 3. vane inlet laying angle β ₁, 4. blade exit laying angle β ₂, 5. impeller outlet diameter D ₂, 6. blade exit width b ₂, 7. number of blade z, 8. subtended angle of blade φ.

Embodiment

To provide the specific implementation process of the inventive method below, it is that 40mPas centrifugal pump impeller step is as follows that design is applicable to fluid viscosity:

Impeller outlet diameter is according to required high viscosity centrifugal pump lift H, flow Q, rotating speed n, and employing formula (1), (2) and (3) are determined:

$D_2=154.39{n_s}^{-0.060}\sqrt[3]{\frac{Q}{n}};n_s\&le;130;---\left(1\right)$

$D_2=(0.0187{n_s}^{0.5}+88.97{n_s}^{-0.5})\sqrt[3]{\frac{Q}{n}};n_s>130;---\left(2\right)$

D ₂₁＝1.5·D ₂(3)

The outlet diameter that impeller inlet diameter calculates according to corresponding specific speed and step 1, adopts formula (4) to determine:

D ₁＝0.04087n _s ^0.5353D ₂₁(4)

Impeller outlet hem width degree is determined by formula (5):

$b_{21}=0.1660{n_s}^{0.4223}\sqrt[3]{\frac{Q}{n}};---\left(5\right)$

Impeller blade cornerite is according to import and export diameter D ₁, D ₂and specific speed, determined by formula (6):

There is certain relation in impeller blade number and specific speed, is determined by formula (7):

$\left\{\begin{array}{cc}z=5~7,& 40\&le;n_s<90\\ z=4~5,& 90\&le;n_s<210\\ z=3,& 210\&le;n_s<300\end{array}\right\}---\left(7\right)$

Adopt double shrouded wheel structure, as specific speed n _swhen≤130, impeller blade import laying angle β ₁get 15 ° ~ 26 °, impeller blade outlet laying angle β ₂get 12 ° ~ 21 °, as specific speed n _sduring > 130, impeller blade import laying angle β ₁get 22 ° ~ 34 °, impeller blade outlet laying angle β ₂get 18 ° ~ 30 °, when design discharge, blade incidence Δ β adopts high incidence, and Δ β gets 3 ° ~ 5 °, and along with the increase of pump specific angular speed, number of blade z trends towards getting smaller value, and entrance edge of blade suitably protracts to suction port.

The experimental technique specified according to " experimental technique of GB3216-1989 centrifugal pump, mixed flow pump, axial-flow pump and peripheral pump " under the same experimental condition of same pump case obtains the hydraulic efficiency of high viscosity centrifugal pump model under design conditions of the inventive method, than the high viscosity centrifugal pump hydraulic efficiency height 2%-5% of traditional design method, and there is good nonblocking performance.

Claims (7)

1. the Hydraulic Design Method of a high viscosity centrifugal pump impeller, described impeller comprises front shroud (1), blade (2), back shroud (3), specific features is, according to designing requirement lift H, flow Q, the parameters such as efficiency eta, the impeller outlet diameter D of design centrifugal pump ₂, impeller inlet diameter D ₁, impeller blade exit width b ₂, subtended angle of blade number of blade z is determined by following relation:

D ₂₁＝(1.35～1.55)·D ₂

D ₁＝ε·D ₂＝0.0409n _s ^0.5353·D ₂₁；

b ₂₁＝k ₀b ₂＝(1.5～1.8)b ₂

In formula:

D ₂-Ordinary Centrifugal Pumps impeller outlet diameter, mm;

D ₂₁-high viscosity centrifugal pump impeller outlet diameter, mm;

N _s-chemical pump specific speed,

Q-pump duty, m ³/ h;

N-revolution speed;

D ₁-impeller inlet diameter, mm;

μ-kinetic viscosity, mPas;

B ₂-Ordinary Centrifugal Pumps blade exit width, mm;

B ₂₁-high viscosity centrifugal blade exit width, mm;

-impeller blade cornerite, °;

β ₁-vane inlet laying angle, °;

β ₂-blade exit laying angle, °;

Z-impeller blade number.

2. the Hydraulic Design Method of a kind of high viscosity centrifugal pump impeller according to claim 1, the kinetic viscosity scope of its main applicable liquid is 0.1 ~ 100mPas, it is characterized in that: impeller outlet diameter is followed proportional, research finds when pump specific angular speed is 130, its Proportional coefficient K _dminimum, therefore different specific speed range intervals matching different proportion Relationship of Coefficients formulas, eventually through the Proportional coefficient K in theoretical and outstanding in a large number Excellent Hydraulic Model Database of Centrifugal Pump determination different specific speed interval _d.

3. the Hydraulic Design Method of a kind of high viscosity centrifugal pump impeller according to claim 1, it is characterized in that: according to the inlet diameter of outlet diameter determination pump, finding by studying Excellent Hydraulic Model Database of Centrifugal Pump outstanding in a large number, under a certain specific speed, importing and exporting the ratio of diameter there is optimum interval, there is exponential relationship ε=0.04087n in ratio ε optimum value and specific speed _s ^0.5353, can the inlet diameter of the better more determination pump of system by impeller outlet diameter.

4. the Hydraulic Design Method of a kind of high viscosity centrifugal pump impeller according to claim 1, is characterized in that: impeller outlet width and be directly proportional, according to a large amount of outstanding Excellent Hydraulic Model Database of Centrifugal Pump databases, set up exit width COEFFICIENT K _bmathematical model, and adopt multiple target hydraulic design optimization method for its efficiency and vapour nonblocking performance 2, set up mathematical model modified, matching K _boptimum formula.

5. the Hydraulic Design Method of a kind of high viscosity centrifugal pump impeller according to claim 1, is characterized in that: adopt double shrouded wheel structure, as specific speed n _swhen≤130, impeller blade import laying angle β ₁get 15 ° ~ 26 °, impeller blade outlet laying angle β ₂get 12 ° ~ 21 °, as specific speed n _sduring > 130, impeller blade import laying angle β ₁get 22 ° ~ 34 °, impeller blade outlet laying angle β ₂get 18 ° ~ 30 °, when design discharge, blade incidence Δ β adopts high incidence, and Δ β gets 3 ° ~ 5 °.

6. the Hydraulic Design Method of a kind of high viscosity centrifugal pump impeller according to claim 1, it is characterized in that: the design of subtended angle of blade is derived from mathematical model aspect, and the formula to cornerite is modified according to fluid mechanics knowledge and design experiences, when for there being the centrifugal pump of particular/special requirement can increase cornerite to meet design requirement, and entrance edge of blade suitably protracts to suction port.

7. the Hydraulic Design Method of a kind of high viscosity centrifugal pump impeller according to claim 1, it is characterized in that: along with the increase of pump specific angular speed, number of blade z trends towards getting smaller value.