CN106202795A - Centrifugal pump impeller and the method for designing thereof of constraint is combined based on entropy product and blade loading - Google Patents

Abstract

The present invention relates to combine centrifugal pump impeller and the method for designing thereof of constraint based on entropy product and blade loading.The method that purpose is to provide can improve design efficiency, it is provided that centrifugal pump impeller can reduce centrifugal pump energy loss.Technical scheme is: a kind of design method for centrifugal pump impeller combining constraint based on entropy product and blade loading, it is characterised in that comprise the following steps: 1) determine that runner blade load is distributed；2) blade geometry model is drawn out；3) verify whether to meet desired physical considerations；4) if leaf model is unsatisfactory for desired physical considerations, then step 1 is returned) repaint blade；5) the energy loss distribution situation of blade is calculated；6) balance pipe of at least one circle is opened；7) CFD simulating, verifying is carried out.A kind of centrifugal pump impeller: comprising six blades, each blade has balance pipe, balance pipe is positioned at the position, middle section that blade is axial, and the distance at the center of balance pipe to vane inlet is the 70%～80% of length of blade.

Description

Centrifugal pump impeller and the method for designing thereof of constraint is combined based on entropy product and blade loading

Technical field

The present invention relates to centrifugal pump impeller technical field, a kind of produce based on entropy and blade loading combine constraint from Heart impeller of pump method for designing, and a kind of centrifugal pump impeller.

Background technology

The internal complicated three-dimensional unsteady flow turbulent of centrifugal pump, often resulting in some affects the bad existing of centrifugal pump operation characteristic As, such as pressure fluctuation, flow separation, hydraulic vibration etc., have a strong impact on run stability and the working life of unit.

At present, traditional Centrifugal Pump Design method, when being designed centrifugal pump, is all to define blade geometry, then enters Row CFD emulates, and the most experimentally revises blade geometry, and CFD result of calculation and how to revise blade geometry without necessary connection, Wherein most amendment is wrong or unnecessary, relies primarily on the design experiences of engineer, causes the wave of time and manpower Take.

Summary of the invention

The technical problem to be solved in the present invention is the deficiency overcoming above-mentioned background technology, it is provided that a kind of Centrifugal Impeller Design Method, it is possible to increase design efficiency, saves design cost, the centrifugal pump impeller designed according to this method for designing, can ensure While lift and efficiency, reduce centrifugal pump energy loss, to improve life-span and the run stability of centrifugal pump.

The technical solution used in the present invention is: a kind of Centrifugal Impeller Design combining constraint based on entropy product and blade loading Method, it is characterised in that comprise the following steps:

1) in the CFD system of computer, archetypal pump is emulated, according to computing formula Determine that runner blade load is distributed；

In formula: p⁺And p^-It is respectively blade pressure surface and suction surface pressure, unit Pa；Z is the number of blade；W_mblFor blade streamline On relative velocity, unit m/s；ρ is the density of water；For velocity circulation, unit m²/s；M is opposite axial faces streamline length；For blade loading；

2) according to loading conditions, after determining two blade loading curves, according to the vane type line differential equationDraw out blade geometry model；

3) the blade geometry model drawn out is carried out whether CFD simulating, verifying meets desired physical considerations；

4) if leaf model is unsatisfactory for desired physical considerations, then step 1 is returned), adjust blade loading distribution, repaint leaf Sheet；

5) if the impeller of design meets desired physical considerations, then theoretical based on Energy-Entropy, according to formula Calculate the energy loss distribution situation of blade；

S″′_DValue obtained by average Navier-Stokes equation, S " '_D′Can be by formulaDrawing, wherein κ and ω is respectively Being the tubulence energy in SST κ-ω model and characteristic frequency, α=0.09 is empirical, and V represents runner volume, in T is centrifugal pump Portion's temperature；

6) according to the energy loss distribution situation of blade, blade occur the main positions of energy loss open at least one Circular balance pipe, balance pipe radius is the 1/5～1/6 of blade exit end width, and balance pipe axial location is positioned in blade and cuts Face；

7) leaf model after perforate is carried out CFD simulating, verifying, if the energy loss of blade is still unsatisfactory for requirement, then change Become blade loading distribution, return step 2), meet, until designing, the blade that energy loss requires.

As preferably, a kind of centrifugal pump impeller, it is characterised in that: comprise six blades, each blade has flat Weighing apparatus hole, balance pipe radius is 4～5mm, and described balance pipe is positioned at the position, middle section that blade is axial, and the center of balance pipe is to blade The distance of import is the 70%～80% of length of blade.

As preferably, described vane thickness is 2～3mm, and vane inlet a diameter of 300～320mm, blade exit is a diameter of 600～640mm, the width of blade exit is 20～25mm, and vane inlet laying angle is 29-30 degree, and blade exit laying angle is 20～24 degree.

The invention has the beneficial effects as follows:

1) method using Energy-Entropy, analyzes the main region of impeller energy loss, and the adjustment for load distribution provides Reference；

2) produce based on entropy and blade loading theory combines constraint, solve centrifugal pump the Hydraulic Design problem, improve design Efficiency, shortens the Centrifugal Pump Design cycle；

3) based on the complete three-dimensional mimetic design method that blade loading is theoretical, calculated by adjustment blade loading distribution and meet The blade geometry of the flow distribution optimized, is greatly improved desin speed, saves a large amount of manpower and time；

4) being no longer strongly depend on the design experiences of engineer, new hand also can attempt being designed；

5) impeller designed by this Optimization Design, can effectively reduce the energy loss of centrifugal pump, improves pump Run stability and service life.

Accompanying drawing explanation

Fig. 1 is the design flow diagram of method for designing of the present invention；

Fig. 2 is impeller axial plane sectional view；

Fig. 3 is impeller front view；

Fig. 4 is blade loading curve；

Fig. 5 is performance curve comparison diagram before and after impeller optimizes；

Fig. 6 is energy loss profiles versus figure before and after impeller optimizes.

Wherein: 1, blade；2, balance pipe；3, front shroud；4, runner；5, back shroud；6, rotating shaft.

Detailed description of the invention

The invention will be further described below, but the invention is not limited in following example.

Seeing Fig. 1 to Fig. 6, a kind of centrifugal pump impeller combining constraint based on entropy product and blade loading that the present invention provides sets Meter method, its archetypal pump design discharge is Q_d=0.008m³/s,H_d=0.1m, n=40r/min.

This method for designing comprises the following steps:

1) to existing archetypal pump, the CFD system of computer carries out numerical simulation (emulation), by according to computing formulaCalculate archetypal pump impeller channel 4 and divide near the blade loading of front shroud 3, back shroud 5 position Cloth, thus determine that the blade loading curve near front shroud and the blade near back shroud carry according to blade loading distribution situation Lotus curve, its front and rear cover plate load is distributed as: front load(ing) point m1=0.38, rear load(ing) point m2=0.82, and middle main loading zone is oblique Rate k=0.8；In formula: p⁺And p^-It is respectively blade pressure surface and suction surface pressure, unit Pa；Z is the number of blade；W_mblFor blade flow Relative velocity on line, unit m/s；ρ is the density of water；For velocity circulation, unit m²/s；M is that opposite axial faces streamline is long Degree；For blade loading；

2) it is distributed according to two blade loading curves (each blade loading curve of front shroud, back shroud) of front and rear cover plate Situation, by the vane type line differential equationDraw out blade geometry model；In formula: v_mBeing flow rate on axial surface, f is leaf Sheet cornerite, ω is blade angular velocity of rotation, and r is the radius of node, V on blade_θFor the peripheral compoent of velocity of node, s is axial plane stream Line length,

3) leaf model drawn out being carried out CFD simulating, verifying, it meets desired physical considerations；

4) by CFD system-computed result, below equation centrifugal pump internal energy loss S is calculated " ' distribution situation:

${\stackrel{\·}{S}}^{\′\′\′}={\stackrel{\·}{S}}_D^{\′\′\′}+{\stackrel{\·}{S}}_{D^{\′}}^{\′\′\′}$

${\stackrel{\·}{S}}_D^{\′\′\′}=\frac{\mathrm{\μ}}{T}(2\[{\left(\frac{\∂\stackrel{\‾}{u}}{\∂x}\right)}^2+{\left(\frac{\∂\stackrel{\‾}{v}}{\∂y}\right)}^2+{\left(\frac{\∂\stackrel{\‾}{w}}{\∂z}\right)}^2\]+{\left(\frac{\∂\stackrel{\‾}{u}}{\∂y}+\frac{\∂\stackrel{\‾}{v}}{\∂x}\right)}^2+{\left(\frac{\∂\stackrel{\‾}{u}}{\∂z}+\frac{\∂\stackrel{\‾}{v}}{\∂x}\right)}^2+{\left(\frac{\∂\stackrel{\‾}{v}}{\∂z}+\frac{\∂\stackrel{\‾}{w}}{\∂y}\right)}^2)$

${\stackrel{\·}{S}}_{D^{\′}}^{\′\′\′}=\frac{\mathrm{\μ}}{T}(2\[{\left(\frac{\∂u^{\′}}{\∂x}\right)}^2+{\left(\frac{\∂v^{\′}}{\∂y}\right)}^2+{\left(\frac{\∂w^{\′}}{\∂z}\right)}^2\]+{\left(\frac{\∂u^{\′}}{\∂y}+\frac{\∂v^{\′}}{\∂x}\right)}^2+{\left(\frac{\∂u^{\′}}{\∂z}+\frac{\∂v^{\′}}{\∂x}\right)}^2+{\left(\frac{\∂v^{\′}}{\∂z}+\frac{\∂w^{\′}}{\∂y}\right)}^2)$

Total rate of entropy production is

In formula: u represents the velocity component along x-axis, v represents the velocity component along y-axis, and w represents the velocity component along z-axis, μ It it is dynamic viscosity.

In formula, S " '_DValue obtained by average Navier-Stokes equation, S " '_D′Can be by formulaDraw, wherein κ and ω Being the tubulence energy in SST κ-ω model and characteristic frequency respectively, α=0.09 is empirical, and V represents runner volume, and T is centrifugal Pump internal temperature (centrifugal pump is internal is isothermal Flow of Single, and what T referred to is also this stationary temperature)；

By analytical calculation, total energy loss distribution situation can be drawn；

5) at axial blade middle section (blade geometrically axially in the middle of position), diametrically blade streamline (i.e. along blade streamline, balance pipe is leaf with the distance of blade inlet to open the balance pipe 2 that radius is 5mm at 75% extension position 75% position of sheet streamline total length), by balance pipe, break up this flow instabilities whirlpool, region, to reduce energy loss；

6) adjust curve of load distribution, impeller be optimized, current load(ing) point m1=0.4, rear load(ing) point m2=0.78, During main loading zone slope k=-4, Minimal energy loss, its energy loss distribution situation can be drawn simultaneously；Designed by optimization, if In the case of its lift of the impeller counted out and efficiency do not reduce, energy loss substantially reduces and (reduces the energy damage of 10% to 20% Lose).

The present invention also provides for a kind of centrifugal pump impeller designed according to above-mentioned method for designing, comprises rotating shaft 6 and six leaves Sheet 1, each blade has balance pipe 2, and balance pipe radius is 4～5mm, described balance pipe be positioned at blade axial in cut Position, face；Along blade streamline, the distance at the center of balance pipe to vane inlet is the 70～80% of length of blade.

Described vane thickness is 2～3mm, vane inlet a diameter of 300～320mm, blade exit a diameter of 600～ 640mm, the width of blade exit is 20～25mm, and vane inlet laying angle is 29-30 degree, and blade exit laying angle is 20～24 Degree.

It is only the specific embodiment of the present invention finally it should be noted that listed above.It is clear that the invention is not restricted to Above example, it is also possible to have many variations.Those of ordinary skill in the art directly can lead from present disclosure The all deformation gone out or associate, are all considered as protection scope of the present invention.

Claims (3)

1. the design method for centrifugal pump impeller combining constraint based on entropy product and blade loading, it is characterised in that include following Step:

1) in the CFD system of computer, archetypal pump is emulated, according to computing formulaDetermine Runner blade load is distributed；

In formula: p⁺And p^-It is respectively blade pressure surface and suction surface pressure, unit Pa；Z is the number of blade；W_mblFor on blade streamline Relative velocity, unit m/s；ρ is the density of water；For velocity circulation, unit m²/s；M is opposite axial faces streamline length；For blade loading；

2) according to loading conditions, after determining two blade loading curves, according to the vane type line differential equationDraw out blade geometry model；

3) the blade geometry model drawn out is carried out whether CFD simulating, verifying meets desired physical considerations；

4) if leaf model is unsatisfactory for desired physical considerations, then step 1 is returned), adjust blade loading distribution, repaint blade；

5) if the impeller of design meets desired physical considerations, then theoretical based on Energy-Entropy, according to formulaCalculate Go out the energy loss distribution situation of blade；

S_D" ' value obtained by average Navier-Stokes equation, S_D′" ' can be by formulaDrawing, wherein κ and ω is SST respectively Tubulence energy in κ-ω model and characteristic frequency, α=0.09 is empirical, and V represents runner volume, and T is the internal temperature of centrifugal pump Degree；

6) according to the energy loss distribution situation of blade, blade occur the main positions of energy loss open at least one circular Balance pipe, balance pipe radius is the 1/5～1/6 of blade exit end width, and balance pipe axial location is positioned at blade middle section；

7) if the energy loss of blade is still unsatisfactory for requirement, then change blade loading distribution, return step 2), until designing full Till the blade that foot energy loss requires.

The centrifugal pump impeller of method for designing design the most according to claim 1, it is characterised in that: comprise six blades, each Having balance pipe on blade, balance pipe radius is 4～5mm, and described balance pipe is positioned at the position, middle section that blade is axial, flat The center in weighing apparatus hole is to distance is length of blade 70%～the 80% of vane inlet.

Centrifugal pump impeller the most according to claim 2, it is characterised in that: described vane thickness is 2～3mm, vane inlet A diameter of 300～320mm, blade exit a diameter of 600～640mm, the width of blade exit is 20～25mm, and vane inlet is pacified Putting angle is 29-30 degree, and blade exit laying angle is 20～24 degree.