CN102146933A - Method for designing inlet edge of impeller of centrifugal pump - Google Patents

Abstract

The invention discloses a method for designing the inlet edge of an impeller of a centrifugal pump, which comprises the following steps; selecting an excellent hydraulic model, preliminarily determining the hydraulic inlet data identified by a line plan of a square grid blade of the excellent hydraulic model as the hydraulic inlet data of the designed blade to obtain the position of the inlet edge, an inlet angle, a computation fluid flow angle and an angle of attack, thereby solving the direct problem of hydraulic computation; and obtaining the inlet flow parameters of each flow line through the corresponding calculation to ensure that each flow line comforts to the corresponding design standard. The method improves an included angle between the blade and a cover plate and avoids the fluid from being extruded in a flow field through the rational design to the inlet edge of the blade, so that when the fluid uniformly flows into the inside of the impeller, not only the flow rules are met, but also the casting process of the impeller can be improved, and in particular, the operating reliability of the centrifugal pump is greatly improved.

Description

A kind of centrifugal pump impeller inlet side design method

Technical field:

What the present invention relates to is centrifugal pump, relates in particular to a kind of method of centrifugal pump impeller inlet side design.

Background technique:

The essential structure of centrifugal pump is made up of six parts, is respectively: impeller, the pump housing, pump shaft, bearing, seal ring, stuffing box.

1, impeller is the core of centrifugal pump, and the high ouput force of its rotating speed is big, and the blade on the impeller plays main effect again, and impeller will be tested by static balancing before assembling.Inner and outer surface on the impeller requires smooth, to reduce the frictional loss of current.

2, the pump housing also claims pump case, and it is the main body of water pump.Play the support fixation effect, and be connected with bearings mounted carriage.

3, the effect of pump shaft is to borrow coupling to be connected with motor, and the commentaries on classics distance of motor is passed to impeller, so it is the critical piece that transmits mechanical energy.

4, bearing is the member that is enclosed within pump shaft upper support pump shaft, and two kinds on rolling bearing and sliding bearing arranged.Rolling bearing uses butter to refuel as oiling agent and wants suitably, is generally 2/3～3/4 volume and can generates heat too much, and sound and heating are arranged again very little, and what sliding bearing used is that clean oil is made oiling agent, refuels the oil level line.Too many oil will ooze out and drifts out along pump shaft, and overheated again the burning out of bearing causes the accident very little.Generally operate in about 60 ℃ at 85 ℃ in that the temperature of water pump operation process middle (center) bearing is the highest, if high will search reason (whether impurity is arranged, and whether oil turns black, and whether intakes) and in time handle.

5, seal ring claims to subtract the leakage ring again.Excesssive gap between impeller inlet and pump case can cause the water in pump inner high voltage district to flow to low pressure area through this gap, influences the water-outlet quantity of pump, and efficient reduces, and the too small meeting in gap causes impeller and the wearing and tearing of pump case friction-produced.Reduce interior the leakage in order to increase the backflow resistance, delay the working life of impeller and pump case, at pump case inner edge and impeller foreign aid junction seal ring is housed, the gap of sealing remains between 0.25～1.10mm is advisable.

6, stuffing box is mainly by filler, seal cage, and filling tube, Gland, water sealing (sealing water) pipe is formed.The effect of stuffing box mainly is in order to seal the space between pump case and the pump shaft, not allow the interior current of pump not flow to the outside and come also not allow the air of outside enter in the pump.Remain the vacuum in the water pump, friction generates heat will keep a grip on water by water seal and in the water seal circle filler be cooled off, the normal operation of maintenance water pump when pump shaft and filler.So the inspection to stuffing box in the operation tours of inspection process of water pump is to be noted that especially in operation will change filler in about 600 hours.

Impeller is installed in the pump case, and is fastened on the pump shaft, before centrifugal pump starts, fills the liquid that is transferred in the pump case; After the startup, impeller drives high speed rotating by axle, and interlobate liquid also must be along with rotation.Under action of centrifugal force, liquid is thrown to outer rim and is obtained energy from the impeller center, so that leaving impeller outer edge enters the volute pump case at a high speed.

The design of the inlet side of centrifugal pump impeller enters impeller inside for fluid key effect, can not only effectively improve fluid the flowing of impeller interior flow field, and also can improve the reliability of unit operation.Simultaneously, the reasonable setting of the inlet side of centrifugal pump impeller also affects the technology of impeller casting.And the clear and definite without comparison method of the inlet side of centrifugal pump impeller design in the prior art in the impeller casting, and all has much room for improvement on the uniform inflow of impeller inlet place fluid.

Summary of the invention:

The present invention seeks to be used for remedying the deficiencies in the prior art, and provide a kind of by reasonably designing the impeller inlet limit, improve the angle between blade and the cover plate, avoid shortcomings such as the flow field inner fluid squeezes, impeller casting difficulty, make the uniform inflow of impeller inlet place fluid, improve the centrifugal pump impeller inlet side design method of unit operation reliability.

To achieve these goals, technological scheme of the present invention is as follows:

A kind of centrifugal pump impeller inlet side design method, this design method realizes by following steps:

(1), choose outstanding hydraulic model, know import waterpower data at its square grid leaf type line chart subscript, the waterpower data that identified tentatively are defined as designing the import figure of blade waterpower;

(2), by step (1) inlet side position, inlet angle as can be known, and calculate flow angle and the angle of attack and corresponding flow parameter by inlet side position and inlet angle;

(3), calculate corresponding flow parameter, its computational process is as follows:

Blade liquid β ' ₁The calculating at stream angle:

$\mathrm{tg}{\mathrm{\β}}_1^{\′}=\frac{v_{m1}}{u_1-v_{u1}}$

β ' in the formula ₁-blade flow angle, v _M1-blade import axis plane velocity;

Determine the v of each streamline _uValue:

v _U1Be by suction chamber (the return guide vane exit angle of multistage pump) structures shape, to straight-tapered suction chamber v _U1=0; To the spirality suction chamber, can determine v by empirical correlation _uR then presses v _uThe R=constant is determined the v of each streamline _uValue, its empirical correlation is:

K＝v _uR＝m(Q ²n) ^1/3

M-empirical coefficient in the formula, m=0.055～0.08

Determining of blade import axis plane velocity:

$v_{m1}=\frac{Q}{{\mathrm{\η}}_v{F}_1{\mathrm{\ψ}}_1}$

F in the formula ₁The flow area of-calculation level;

ψ ₁-the blade excretion coefficient, its computational process is as follows:

${\mathrm{\ψ}}_1=1-\frac{{\mathrm{zs}}_{u1}}{2\mathrm{\π}{R}_1}=1-\frac{z{\mathrm{\δ}}_1}{2\mathrm{\π}{R}_1}\sqrt{1+\frac{1}{{\left(\mathrm{tg}{\mathrm{\β}}_1\sin {\mathrm{\λ}}_1\right)}^2}}$

(4), judge and the position of axial plane transversal to be divided into two kinds of situations usually:

1., entrance edge of blade when same axial plane, the axial plane transversal of crossing entrance edge of blade and each streamline intersection point is identical;

2., entrance edge of blade not when same axial plane, the axial plane transversal of crossing entrance edge of blade and each streamline intersection point is inequality;

(5), at the 2. planting situation in the step (4), how summary made the axial plane transversal of each streamline intersection point:

In square grid leaf type line chart, cross certain streamline intersection point and make vertical curve (axial plane), with each streamline (elongation line) intersection point, according to each intersection point position on the streamline (elongation line) in square grid leaf type line chart, in axial plane figure, make respective point, link to each other with smoothed curve, be the axial plane transversal of certain streamline intersection point, remaining streamline intersection point axial plane transversal practice and above-mentioned same.

The present invention is by the appropriate design to entrance edge of blade, improved the angle between blade and the cover plate, avoided the flow field inner fluid to squeeze, not only meet flowing law but also can improve the manufacturability that impeller is cast when making fluid evenly enter the impeller interior flow field, more the centrifugal pump reliability of operation is enhanced.

Description of drawings:

Further specify the present invention below in conjunction with the drawings and specific embodiments.

Fig. 1 is an entrance edge of blade schematic representation of the present invention

Fig. 2 is a square grid leaf type line chart of the present invention

Embodiment:

For technological means, creation characteristic that the present invention is realized, reach purpose and effect is easy to understand, below in conjunction with concrete diagram, further set forth the present invention.

A kind of centrifugal pump impeller inlet side design method, this design method realizes by following steps:

(1), choose outstanding hydraulic model, know import waterpower data at its square grid leaf type line chart subscript, the waterpower data that identified tentatively are defined as designing the import figure of blade waterpower;

(2), by step (1) inlet side position, inlet angle as can be known, and calculate flow angle and the angle of attack and corresponding flow parameter by inlet side position and inlet angle;

(3), calculate corresponding flow parameter, its computational process is as follows:

Blade liquid β ' ₁The calculating at stream angle:

$\mathrm{tg}{\mathrm{\β}}_1^{\′}=\frac{v_{m1}}{u_1-v_{u1}}$

β ' in the formula ₁-blade flow angle, v _M1-blade import axis plane velocity,

Determine the v of each streamline _uValue:

v _U1Be by suction chamber (the return guide vane exit angle of multistage pump) structures shape, to straight-tapered suction chamber v _U1=0; To the spirality suction chamber, can determine v by empirical correlation _uR then presses v _uThe R=constant is determined the v of each streamline _uValue, its empirical correlation is:

K＝v _uR＝m(Q ²n) ^1/3

M-empirical coefficient in the formula, m=0.055～0.08

Determining of blade import axis plane velocity:

$v_{m1}=\frac{Q}{{\mathrm{\η}}_v{F}_1{\mathrm{\ψ}}_1}$

F in the formula ₁The flow area of-calculation level

ψ ₁-the blade excretion coefficient, its computational process is as follows:

${\mathrm{\ψ}}_1=1-\frac{{\mathrm{zs}}_{u1}}{2\mathrm{\π}{R}_1}=1-\frac{z{\mathrm{\δ}}_1}{2\mathrm{\π}{R}_1}\sqrt{1+\frac{1}{{\left(\mathrm{tg}{\mathrm{\β}}_1\sin {\mathrm{\λ}}_1\right)}^2}}$

(4), judge and the position of axial plane transversal to be divided into two kinds of situations usually:

1., entrance edge of blade when same axial plane, the axial plane transversal of crossing entrance edge of blade and each streamline intersection point is identical;

2., entrance edge of blade not when same axial plane, the axial plane transversal of crossing entrance edge of blade and each streamline intersection point is inequality;

(5), at the 2. planting situation in the step (4), how summary made the axial plane transversal of each streamline intersection point:

With reference to illustrated in figures 1 and 2: the axial plane transversal of crossing entrance edge of blade and each streamline intersection point when same axial plane is identical, not when same axial plane, as shown above, the axial plane transversal of crossing 4 of inlet side and each streamline intersection point a, b, c, d is different, dotted line among the figure was the axial plane transversal that a is ordered, and calculate the λ of certain point ₁This point should be crossed in angle, axial plane transversal.

Be example with a point now, how summary made the axial plane transversal of this point: in square grid leaf type line chart, cross a point and make vertical curve (axial plane), with each streamline (elongation line) intersection point, according to each intersection point position on the streamline (elongation line) in square grid leaf type line chart, in axial plane figure, make respective point, link to each other, be the axial plane transversal that a is ordered with smoothed curve.Cross b, c ... the axial plane transversal practice of putting and above-mentioned same, four streamlines that draw in square grid are exactly four molded lines of blade surface.Remove to cut these four streamlines with axial plane (vertical line that is equivalent to square grid), be equivalent to remove to wear blade with axial plane, 4 the line of cutting is an axial plane transversal.In the square grid every the vertical line of several angle and the intersection point of four streamlines, the position of reference numeral a, b, c......, put respectively on corresponding four streamlines of axis projection with insertion, institute's invocation point is linked to be smooth curve, just obtain the axial plane transversal of blade, the axial plane transversal should be smooth, changes according to certain rules, the included angle X of axial plane transversal and streamline generally is not less than 60 ° preferably near 90 °.

The present invention is by the appropriate design to entrance edge of blade, improved the angle between blade and the cover plate, avoided the flow field inner fluid to squeeze, not only meet flowing law but also can improve the manufacturability that impeller is cast when making fluid evenly enter the impeller interior flow field, the centrifugal pump reliability of operation is enhanced.

More than show and described basic principle of the present invention and major character and advantage of the present invention.The technician of the industry should understand; the present invention is not restricted to the described embodiments; that describes in the foregoing description and the specification just illustrates principle of the present invention; without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications, and these changes and improvements all fall in the claimed scope of the invention.The claimed scope of the present invention is defined by appending claims and equivalent thereof.

Claims (1)

1. centrifugal pump impeller inlet side design method is characterized in that this design method realizes by following steps:

(1), choose outstanding hydraulic model, know import waterpower data at its square grid leaf type line chart subscript, the waterpower data that identified tentatively are defined as designing the import figure of blade waterpower;

(2), by step (1) inlet side position, inlet angle as can be known, and calculate flow angle and the angle of attack and corresponding flow parameter by inlet side position and inlet angle;

(3), calculate corresponding flow parameter, its computational process is as follows:

Blade liquid β ' ₁The calculating at stream angle:

$\mathrm{tg}{\mathrm{\β}}_1^{\′}=\frac{v_{m1}}{u_1-v_{u1}}$

β ' in the formula ₁-blade flow angle, v _M1-blade import axis plane velocity;

Determine the v of each streamline _uValue:

v _U1By the suction chamber structures shape, to straight-tapered suction chamber v _U1=0; To the spirality suction chamber, can determine v by empirical correlation _uR then presses v _uThe R=constant is determined the v of each streamline _uValue, its empirical correlation is:

K＝v _uR＝m(Q ²n) ^1/3

M-empirical coefficient in the formula, m=0.055～0.08

Determining of blade import axis plane velocity:

$v_{m1}=\frac{Q}{{\mathrm{\η}}_v{F}_1{\mathrm{\ψ}}_1}$

F in the formula ₁The flow area of-calculation level;

ψ ₁-the blade excretion coefficient, its computational process is as follows:

${\mathrm{\ψ}}_1=1-\frac{{\mathrm{zs}}_{u1}}{2\mathrm{\π}{R}_1}=1-\frac{z{\mathrm{\δ}}_1}{2\mathrm{\π}{R}_1}\sqrt{1+\frac{1}{{\left(\mathrm{tg}{\mathrm{\β}}_1\sin {\mathrm{\λ}}_1\right)}^2}}$

(4), judge and the position of axial plane transversal to be divided into two kinds of situations usually:

1., entrance edge of blade when same axial plane, the axial plane transversal of crossing entrance edge of blade and each streamline intersection point is identical;

2., entrance edge of blade not when same axial plane, the axial plane transversal of crossing entrance edge of blade and each streamline intersection point is inequality;

(5), at the 2. planting situation in the step (4), how summary made the axial plane transversal of each streamline intersection point, its concrete steps are as follows:

In square grid leaf type line chart, cross certain streamline intersection point and make vertical curve, with each streamline intersection point, according to each intersection point position on the streamline in square grid leaf type line chart, in axial plane figure, make respective point, link to each other with smoothed curve, be the axial plane transversal of certain streamline intersection point, remaining streamline intersection point axial plane transversal practice and above-mentioned same.

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