CN104088811B - A kind of anti-eddy current high voltage motor double rotational directions centrifugal fan method for designing - Google Patents

Abstract

The present invention relates to a kind of anti-eddy current high voltage motor double rotational directions centrifugal fan method for designing. In motor operation course, blade can be produced certain eddy current by wind side region, for suppress eddy current, on the basis of former fan, increased guide vane. Guide vane is positioned at two interlobate eddy current positions, because the rotation direction of fan is two-way, thus a slice guide vane is each side being set, because flow deflector has increased the frictional dissipation of fan, so former fan blade suitably can be reduced. It is comparatively reasonable that blade quantity is reduced to the 1/2-2/3 of former fan, can calculate fan blade number by formula without original design. Two flow deflector designs have ensured no matter fan rotates to which direction, and the eddy current between fan blade all can be suppressed.

Description

A design method of anti-eddy-current high-voltage motor double-rotation centrifugal fan

technical field

The invention relates to a design method for a double-rotational centrifugal fan of an anti-eddy current high-voltage motor, belonging to the field of high-voltage motor cooling fans.

Background technique

With the country's emphasis on energy conservation and emission reduction, various measures and norms have been introduced successively. Among them, the induction motor has a large volume and a wide range, and the annual power consumption accounts for about 57% of the entire power generation, while the high-voltage three-phase asynchronous motor accounts for a large proportion of the loads supported by the induction motor, and the high-voltage motor usually works for a long time The load rate is generally high, so it is of great significance to improve the efficiency of high-voltage motors.

As the electromagnetic design of high-voltage three-phase asynchronous motors has become mature, it has become more and more difficult to improve the efficiency of the motor by rationally designing the electromagnetic structure of the motor. Due to the rationality of the structure of the high-voltage motor and its high efficiency, it is necessary to increase a large amount of effective materials on the basis of the original motor to improve the efficiency, which greatly increases the manufacturing cost and consumes non-renewable resources such as copper, aluminum, and iron. It can be seen that through Increasing the effective material of the motor to improve the efficiency has become outweighed, and the role of improving the efficiency of the motor through other means is becoming more and more important.

Compared with small and medium-sized motors, high-voltage motors are larger in size, generate more heat, and have more complicated ventilation. The mechanical loss of high-voltage motors accounts for about 20%-30% of the total loss, which is a large proportion. The two poles of traditional high-voltage motors use axial flow fans, while 4, 6, 8, 10, and 12 pole motors can only use centrifugal fans due to their low speed. The installation position of centrifugal fans is shown in Figure 1. The structure of the fans Including fan blade B and fan plate C, fixed on the shaft E of the motor through the rib D, when the motor is running, the fan rotates with the shaft, and the air is used to cool the end A of the stator winding. Because the insulation at the end A of the stator winding is thicker and not as good as the thermal conductivity of the material around the winding in the core, high-voltage motors are generally ventilated and dissipated by centrifugal fans, which are widely used. Common types of traditional high-voltage motor centrifugal fan blades are shown in Figures 2A to 2C, of which the forward-leaning type is shown in Figure 2A, the radial type is shown in Figure 2B, and the backward-leaning type is shown in Figure 2C. The eddy current between the blades of the backward inclined fan is small, the air volume is small, and the fan efficiency is high; the eddy current of the forward inclined fan is large, the air volume is large, and the fan efficiency is low; the radial blade is a divergent fan, the eddy current is large, and the loss and The air volume is in the middle and the fan efficiency is low. Too few fan blades of high-voltage motors will easily lead to shedding phenomenon, and the efficiency of the fan will decrease. Too many blades will easily increase the friction loss along the process, which will also reduce the efficiency of the fan. The number of blades commonly used in high-voltage motors is generally between 12 and 24.

At this stage, the centrifugal fans of high-voltage motors have the following defects:

1. Although the performance of the backward inclined fan is superior, but the direction of rotation is single, the application range is very limited, and it cannot be used in many working conditions;

2. The forward-leaning fan has a large air volume, but the loss is large, which is not conducive to improving the efficiency of the motor, and the rotation direction is a single rotation direction, which limits the application range and cannot be used in many working conditions;

3. The blades of the radial fan are vertically distributed, and the direction of rotation is bidirectional, so it has a strong ability to apply to working conditions and is the most widely used. However, due to the large eddy current between the fan blades, the efficiency of the fan is low.

Among the patents related to the fan design of high-voltage three-phase asynchronous motors, the patent No. CN101383541A "Design method of high-efficiency backward centrifugal cooling external fan for high-voltage asynchronous motors" and the patent No. CN202172334U "a centrifugal fan for high-power high-speed motors" are both The single-rotation backward-tilted fan cannot solve the problem of the two-way rotation of the motor.

In the design of radial fans for high-voltage motors, there is no design method for specifically suppressing eddy currents.

The above-mentioned defects of the high-voltage motor centrifugal fan make it impossible to achieve the unity of efficiency and application range in the design of the high-voltage motor fan. Due to their own characteristics, the forward inclined fan and the backward inclined fan cannot be used in both directions, so they cannot be widely used in high-voltage motors.

Contents of the invention

The technical problem to be solved by the present invention is to rationally design the structure of the high-voltage motor radial fan, reduce the eddy current between the blades, increase the air volume of the fan, and thus improve the efficiency of the fan.

In order to solve the above-mentioned technical problems, the technical solution of the present invention is to provide a design method for a double-rotating centrifugal fan of an anti-eddy current high-voltage motor, which is characterized in that the steps are:

The first step is to select the standard high-voltage motor radial fan;

The second step is to calculate the eddy current range and fan air volume between the adjacent blades of the radial fan of the benchmark high-voltage motor;

The third step is to reduce the number of blades of the standard high-voltage motor radial fan to the original 1/2-2/3, or find the number N of fan blades, N is smaller than the standard high-voltage motor radial fan The number of blades of the , and D ₁ and D ₂ are the inner diameter and outer diameter of the fan blade, respectively;

The fourth step is to add two guide vanes arranged left and right between two adjacent fan blades, namely the left guide vane and the right guide vane, and define the fan blade adjacent to the left guide vane as the left fan blade , the fan blade adjacent to the right guide vane is defined as the right fan blade, area 1 is formed between the left fan blade and the left guide vane, area 2 is formed between the left guide vane and the right guide vane, right guide vane Area three is formed between the blade and the right fan blade; the length of the left fan blade and the right fan blade is equal to h1, the length of the left guide vane and the right guide vane is equal to h2, and the distance between the left guide vane and the left fan blade The distance between is equal to the distance between the right guide vane and the right fan blade is L2, and the distance between the left fan blade and the right fan blade is L1;

The fifth step, select the value of h2/h1 and L2/L1;

The sixth step is to calculate the eddy current range of each area one (I), area two (II) and area three (III). At this time, it should be ensured that in area one (I), area two (II) and area three (III) Inside:

1) There will be no obvious eddy current and backflow phenomenon due to the small value of h1/h2;

2) There will be no obvious vortex phenomenon on both sides of the left guide vane and the right guide vane due to the large value of h1/h2;

3) No obvious vortex phenomenon will be generated between the left guide vane and the right guide vane because the value of L2/L1 is too small;

4) Large-scale eddy currents will not be generated between the left guide vane and the left fan blade and between the right guide vane and the right fan blade due to the large value of L2/L1;

Step 7: After re-selecting the values of h2/h1 and L2/L1, repeat step 6 until multiple schemes with the least obvious eddy current between the blades are obtained. A set of h2/h1 and L2/L1 values corresponds to a square;

The eighth step is to calculate the fan air volume of each scheme, and select the scheme with the largest fan air volume as the final design scheme of the anti-eddy current high-voltage motor double-rotation centrifugal fan, and the fan air volume of the final design scheme must be greater than the fan air volume value obtained in the second step .

During the operation of the motor, a certain vortex will be generated in a certain area of the blade on the windward side. In order to suppress the vortex, guide vanes are added on the basis of the original fan. The guide vane is located in the vortex between the two blades. Since the rotation direction of the fan is bidirectional, a guide vane is installed on the left and right sides. Since the guide vane increases the friction loss of the fan, the original fan blade can be properly decrease. It is more reasonable to reduce the number of blades to 1/2-2/3 of the original fan. Without the original design, the number of fan blades can be calculated by formula. The double deflector design ensures that no matter which direction the fan rotates, the eddy flow between the fan blades will be suppressed.

The invention has the advantages of effectively reducing the eddy current between the fan blades and increasing the air volume of the high-voltage motor. On the one hand, while ensuring the same amount of motor materials, the ventilation air volume is increased, the temperature rise of the motor is reduced, that is, the copper and aluminum consumption of the motor is reduced, and electric energy is saved; on the other hand, while the motor ventilation air volume is guaranteed to be the same In some cases, the amount of effective materials used in the motor can be reduced, the cost of the motor can be effectively reduced, and non-renewable resources such as copper, iron, and aluminum can be saved.

Description of drawings

Figure 1 is an installation diagram of a high-voltage motor centrifugal fan;

Fig. 2A is a schematic diagram of a forward-leaning fan blade;

Fig. 2B is a schematic diagram of a radial fan blade;

Fig. 2C is a schematic diagram of a backward inclined fan blade;

Figure 3 is a diagram of a high-voltage motor radial centrifugal fan;

Fig. 4 is a diagram of a radial centrifugal fan of an anti-eddy current high voltage motor;

Figure 5 is a partial view of the anti-eddy current high voltage motor radial centrifugal fan;

Figure 6 shows the design process of the anti-eddy current high voltage motor radial centrifugal fan.

detailed description

In order to make the present invention more comprehensible, preferred embodiments are described in detail below with accompanying drawings.

In this embodiment, a H500-4 high-voltage three-phase asynchronous motor is used as an object. By reducing the number of blades and adding guide vanes on the original fan of the motor, the eddy current between the fan blades is reduced, and the air volume of the fan is increased, so as to improve the fan. performance purposes.

Referring to Fig. 6, the steps of a design method for a bi-rotating centrifugal fan of an anti-eddy current high-voltage motor disclosed in this embodiment are as follows:

Step A. Select a H500-4 ordinary high-voltage three-phase asynchronous motor fan as a reference. The structure diagram of the fan is shown in Figure 3. The number of blades is 14 and the speed is set to 1450r/min.

In step B, a certain vortex will be generated in the area IV on the windward side of the blade, and the calculated vortex range in the area IV is very large, which is close to 1/2 of the width of the channel between the blades. The calculated air volume of the fan is 1.38697[kgs^-1].

CFD software can be used for computer-aided calculation; or the space between the two fans can be divided into several small areas, and calculated according to the formula (1) and formula (2) of the RNGk-ε model commonly used in engineering:

$\frac{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; k</span>}}{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; div</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; \&PartialD;</span>}{<span\; class="notranslate">\; \&PartialD;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; \&PartialD;</span>}_{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; eff</span>}}\frac{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; k</span>}}{<span\; class="notranslate">\; \&PartialD;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$

$\frac{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; div</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; \&PartialD;</span>}{<span\; class="notranslate">\; \&PartialD;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; \&PartialD;</span>}_{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; eff</span>}}\frac{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}{<span\; class="notranslate">\; \&PartialD;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&rho;\&epsiv;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$

In formula (1) and formula (2): ${\mathrm{\&mu;}}_{eff}={\mathrm{\&rho;C}}_{\mathrm{\&mu;}}\frac{k^2}{\mathrm{\&epsiv;}},$ $G_k=2{\mathrm{\&mu;}}_t\stackrel{\&OverBar;}{S_{\mathrm{ij}}{S}_{\mathrm{ij}}},$ $\stackrel{\&OverBar;}{S_{\mathrm{ij}}}=\frac{1}{2}(\frac{\&PartialD;{\mathrm{\&mu;}}_i}{\&PartialD;x_j}+\frac{\&PartialD;{\mathrm{\&mu;}}_j}{\&PartialD;x_i}),$ μ _i , μ _j (i, j=1, 2, 3) are time-uniform velocity components, x _i , x _j (i, j=1, 2, 3) are coordinate components representing space, ρ is fluid density, μ _eff is fluid dynamic viscosity, G _k is turbulent kinetic energy generation item, S _ij is average strain rate tensor, C ₁ =1.42, C ₂ =1.68, α _k =1.39, C _μ =0.0845, t is time variable, k is the turbulent pulsating kinetic energy, ε is the dissipation rate of turbulent pulsating kinetic energy.

Step C. Reduce the number of fans of the original fan to about 2/3. Since the number of blades of the original fan is 14 pieces, the number of fans is preferably 10 pieces now.

also available through To determine the number N of fans, D ₁ and D ₂ are the inner and outer diameters of the fan blades, respectively.

Step D, as shown in Figure 4 and Figure 5, add two guide vanes arranged left and right between the adjacent two fan blades, which are respectively the left guide vane 2 and the right guide vane 3, which will be connected with the left guide vane 2 The adjacent fan blades are defined as left fan blades 1, and the fan blades adjacent to the right guide vane 3 are defined as right fan blades 4, and an area I, left A zone II II is formed between the guide vane 2 and the right guide vane 3 , and a zone III III is formed between the right guide vane 3 and the right fan blade 4 . The lengths of the left fan blade 1 and the right fan blade 4 are equal to h1, the lengths of the left guide vane 2 and the right guide vane 3 are equal to h2, and the distance between the left guide vane 2 and the left fan blade 1 is equal to the right The distance between the guide vane 3 and the right fan blade 4 is L2, and the distance between the left fan blade 1 and the right fan blade 4 is L1. The shape of the guide vane coincides with the shape of the track swept by the fan blade, and the outer diameter of the guide vane is the same as that of the fan. Take h2/h1=1/2 and L2/L1=1/3.

Step E, calculation can be obtained that the vortex between the fan blades is mainly concentrated in the area I between the left fan blade 1 and the left guide vane 2, which accounts for 1/3 of the channel between the fan blades, and the left guide vane 2 and the right guide vane There is no obvious eddy current in the area II II between the blades 3, and there is a small eddy current on the right side of the right guide vane 3 (windward side) in the area III III. This scheme has a smaller eddy current and is an alternative.

The calculation method can use CFD software to carry out computer-aided calculation, and can also perform calculation according to the above-mentioned formula (1) and formula (2).

Step F, considering whether the vortex range between the left fan blade 1 and the left guide vane 2 can be further reduced, shortening the distance L2 between the right guide vane 3 and the right fan blade 4 .

Repeat step D, and shorten the L2 distance on the basis of step D, taking h2/h1=1/2 and L2/L1=2/7.

Repeat step E and calculate that the vortex after adding the guide vane is still mainly concentrated in the area I between the left fan blade 1 and the left guide vane 2, which accounts for 2/7 of the channel between the fan blades, which is smaller than that in step D There is no obvious vortex in area II II between left guide vane 2 and right guide vane 3, and there is very small vortex on the right side (windward side) of right guide vane 3 in area three III. It can be seen that the scheme of L2/L1=2/7 should be slightly better than the scheme of L2/L1=1/3. This option is option two.

Repeat step F, and continue to shorten the distance L2 between the right guide vane 3 and the right fan blade 4 .

Repeat step D, shorten the L2 distance on the basis of step D, take h2/h1=1/2 and L2/L1=1/4.

Repeating step E and calculating, the vortex between the fan blades after the guide vane is added is mainly concentrated in the area II II between the left guide vane 2 and the right guide vane 3, and the vortex phenomenon is very obvious. It can be seen that this plan is unreasonable.

Repeat step F. Considering that shortening the length of the guide vane can reduce friction loss, shorten the length h2 of the guide vane.

Repeat step D, shorten the length h2 of the guide vane on the basis of step D-1, and take h2/h1=1/3 and L2/L1=2/7.

Repeat step E and calculate that the vortex after adding the guide vane is still mainly concentrated in the area I between the left fan blade 1 and the left guide vane 2, which accounts for 2/7 of the channel between the fan blades, which is smaller than that in step D 1/3 of that, but there is a backflow phenomenon on both sides of the right guide vane 3, that is, a part of the fluid in area 2 II flows around the bottom of the right guide vane to area 3 III, but it is not very obvious. This solution is an alternative third solution.

Repeat step F, considering whether the vortex between the fan blades can be reduced by lengthening the length h2 of the guide vane, and increase the length h2 of the guide vane.

Repeat step D, lengthen the length h2 of the guide vane on the basis of step D-1, take h2/h1=2/3 and L2/L1=2/7.

Repeat step E, and calculate that after the guide vane is added, there are large vortices in the area I, area II, and area III III between the fan blades. It can be seen that the length h2 of the guide vane is longer, resulting in the guide vane The eddy current phenomenon is generated by itself, that is, the overall eddy current between the fan blades is relatively large, which shows that this scheme is unreasonable.

Through repeated calculations between steps D and E, the alternatives are obtained in order of streamline rationality:

Alternative 1 design: h2/h1 = 1/2 and L2/L1 = 2/7

Alternative 2 design: h2/h1 = 1/2 and L2/L1 = 1/3

Alternative 3 design: h2/h1 = 1/3 and L2/L1 = 2/7

The air volumes of the three schemes in step G and calculation step F are obtained:

Option 1 Air volume: 2.11208[kg/s]

Option 2 Air volume: 2.02231[kg/s]

Option 3 Air volume: 1.40079[kg/s]

It can be seen that the air volume of the above three alternatives is better than 1.38697 [kg/s] of the original motor fan, and the design of alternative 1 is the most reasonable.

Note: This example is only to illustrate the design process. In actual design, the values of h2/h1 and L2/L1 can be adjusted more carefully according to this method to obtain the maximum air volume.

Claims (1)

1. an anti-eddy current high voltage motor double rotational directions centrifugal fan method for designing, is characterized in that, step is:

The first step, select benchmark high-voltage motor radial fan;

Second step, calculate eddy current scope and fan wind between the adjacent flabellum of benchmark high-voltage motor radial fanValue;

The 3rd step, the sheet number of the flabellum of benchmark high-voltage motor radial fan is reduced to original 1/2-2/3,Or the sheet of asking for flabellum counts N, N is less than the sheet number of the flabellum of benchmark high-voltage motor radial fan, andD₁And D₂Be respectively internal diameter and the external diameter of flabellum;

The 4th step, two guide vanes that increase left and right is arranged between adjacent two flabellums, be respectively left water conservancy diversion leafSheet (2) and right guide vane (3), be defined as left flabellum (1) by the flabellum adjacent with left guide vane (2),The flabellum adjacent with right guide vane (3) is defined as to right wing leaf (4), left flabellum (1) and left guide vane(2) between, form between region one (I), left guide vane (2) and right guide vane (3) and form regionBetween two (II), right guide vane (3) and right wing leaf (4), form region three (III); Left flabellum (1)With the h1 that is equal in length of right wing leaf (4), the length of left guide vane (2) and right guide vane (3)Equate to be h2, the distance between left guide vane (2) and left flabellum (1) equals right guide vane (3)And the distance between right wing leaf (4) is L2, the distance between left flabellum (1) and right wing leaf (4) is L1;

The value of the 5th step, selected h2/h1 and L2/L1;

The 6th step, calculate the eddy current of regional one (I), region two (II) and region three (III)Scope, now should ensure in region one (I), region two (II) and region three (III):

1) can not produce because h1/h2 value is too little obvious eddy current and backflow phenomenon;

2) can not produce at left guide vane (2) and right guide vane (3) both sides too greatly because of h1/h2 valueRaw obvious vortex phenomenon;

3) can between left guide vane (2) and right guide vane (3), not produce because L2/L1 value is too littleObviously vortex phenomenon;

4) can be too not large between left guide vane (2) and left flabellum (1) and lead on the right side because of L2/L1 valueBetween stream blade (3) and right wing leaf (4), produce vortex phenomenon on a large scale;

After the value of the 7th step, again selected h2/h1 and L2/L1, repeat the 6th step, until obtain between flabellumThe least obvious multiple schemes of eddy current, the corresponding scheme of value of one group of h2/h1 and L2/L1;

The 8th step, calculate the air quantity of fan of each scheme, choose the maximum scheme of air quantity of fan as anti-eddy current high voltageThe final design scheme of motor double rotational directions centrifugal fan, and the air quantity of fan of this final design scheme must be greater thanThe fan wind value that second step obtains.