CN114880968B - Water ring vacuum pump shell molded line design method - Google Patents
Water ring vacuum pump shell molded line design method Download PDFInfo
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- CN114880968B CN114880968B CN202210595655.2A CN202210595655A CN114880968B CN 114880968 B CN114880968 B CN 114880968B CN 202210595655 A CN202210595655 A CN 202210595655A CN 114880968 B CN114880968 B CN 114880968B
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 92
- 238000000034 method Methods 0.000 title claims abstract description 54
- 230000004044 response Effects 0.000 claims abstract description 35
- 230000006835 compression Effects 0.000 claims abstract description 34
- 238000007906 compression Methods 0.000 claims abstract description 34
- 238000000605 extraction Methods 0.000 claims abstract description 25
- 238000002474 experimental method Methods 0.000 claims abstract description 16
- 238000005086 pumping Methods 0.000 claims abstract description 13
- 238000005457 optimization Methods 0.000 claims abstract description 9
- 230000005514 two-phase flow Effects 0.000 claims abstract description 8
- 239000007788 liquid Substances 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 6
- 239000012530 fluid Substances 0.000 claims description 5
- 238000011160 research Methods 0.000 claims description 4
- 230000008859 change Effects 0.000 claims description 3
- 230000001502 supplementing effect Effects 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000010587 phase diagram Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000004323 axial length Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000013400 design of experiment Methods 0.000 description 1
- 238000012938 design process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- -1 metallurgy Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
Classifications
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
- G06F30/28—Design optimisation, verification or simulation using fluid dynamics, e.g. using Navier-Stokes equations or computational fluid dynamics [CFD]
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2113/00—Details relating to the application field
- G06F2113/08—Fluids
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
Abstract
The invention discloses a water ring vacuum pump shell molded line design method, which relates to the related field of water ring vacuum pumps and comprises the following steps: the method comprises the steps of setting shell molded lines in sections and control variables, and designing a four-section shell molded line response surface experiment of the 8 factor 3 horizontal water ring vacuum pump based on a response surface method; calculating a new shell molded line based on a NURBS free-form surface deformation method aiming at each group of shell molded line response surface experiments; establishing a water ring vacuum pump calculation domain model aiming at each group of shell molded lines, and performing CFD calculation by adopting a VOF two-phase flow model to obtain extraction quantity; establishing a second-order response surface model of the extraction quantity and a quadratic polynomial regression equation; and (3) taking the maximum extraction amount as an optimization target, and establishing a new shell molded line based on the NURBS free-form surface deformation method. The invention divides the molded line of the water ring vacuum pump housing into 4 sections, and the designed molded line of the housing is connected smoothly, so that the stable operation of the water ring vacuum pump is ensured, the flow loss is reduced, and the pumping efficiency and isothermal compression efficiency of the water ring vacuum pump are improved.
Description
Technical Field
The invention relates to the technical field related to water ring vacuum pumps, in particular to a water ring vacuum pump shell molded line design method.
Background
The water ring vacuum pump belongs to a volumetric pump, uses liquid as an intermediate medium for energy transmission, and is a general machine for pumping gas. The water-ring vacuum pump has the advantages of compact structure, isothermal compression and the like, can be used for sucking flammable and explosive gas and water-containing dust-containing gas, and is widely applied to the fields of industries such as petroleum, metallurgy, medicine, coal mine, electric power, food and the like. The water ring vacuum pump mainly comprises pump shafts, impellers, distribution plates, a shell, air suction and exhaust ports, pump covers and other parts. The impeller of the water ring vacuum pump is eccentrically arranged in the shell, and when the impeller rotates, liquid injected into the pump is thrown to the inner wall of the shell due to the action of centrifugal force, so that a liquid ring with the shape similar to the shell and the thickness approximately equal to the shape of the shell is formed. A crescent space is formed between the inner surface of the liquid ring rotating along with the impeller and the impeller hub, the containing cavity enclosed between two adjacent blades is gradually enlarged, and gas is sucked from the outside. As the impeller continues to rotate, the corresponding chamber becomes smaller from large to small, so that the gas originally sucked in is compressed, and the gas is discharged when the pressure reaches the atmospheric pressure.
The water ring vacuum pump has the outstanding problems of high energy consumption and low efficiency. The most important factor affecting the working efficiency of water ring vacuum pumps is flow loss. The flow loss is a mechanical energy loss caused by flow resistance, and is closely related to a vortex loss caused by unreasonable flow passage of the housing. Most of domestic and foreign water ring vacuum pump researchers and production manufacturers adopt circular shell molded lines, the design and the manufacture are simple and convenient, but the circular shell molded lines have larger flow loss of the water ring vacuum pump, smaller extraction quantity and low isothermal compression efficiency, and a plurality of water ring vacuum pumps are often required to be connected in parallel to increase the extraction quantity. Foreign researchers have proposed to design a shell profile by a three-segment arc method to optimize the performance of the water ring vacuum pump, and compared with a circular shell profile, the water ring vacuum pump performance is improved to a certain extent, but the three-segment arc shell profile cannot be connected smoothly. The main problems existing in the existing research are that the molded line of the water ring vacuum pump shell is unreasonable, so that the flow loss is large, the pumping quantity is insufficient, and the isothermal compression efficiency is low.
In conclusion, the water-ring vacuum pump shell molded line is scientific and reasonable in design, and has important significance in reducing the flow loss of the shell flow channel and improving the isothermal compression efficiency. Along with the continuous upsizing of the water ring vacuum pump, the design method of the high-efficiency shell molded line of the water ring vacuum pump is an urgent technical problem to be solved by the technicians in the field.
Disclosure of Invention
The invention aims to provide a water ring vacuum pump shell molded line design method, which is used for solving the problems in the prior art, dividing the water ring vacuum pump shell molded line into 4 sections, and realizing smooth connection of the designed high-efficiency shell molded line, ensuring the stable operation of the water ring vacuum pump, reducing the flow loss and improving the pumping efficiency and isothermal compression efficiency of the water ring vacuum pump.
In order to achieve the above object, the present invention provides the following solutions:
the invention provides a water ring vacuum pump shell molded line design method, which comprises the following steps:
1) The method comprises the steps of setting shell molded lines in sections and control variables, and designing a four-section shell molded line response surface experiment of the 8 factor 3 horizontal water ring vacuum pump based on a response surface method;
2) Calculating a new shell molded line based on a NURBS free-form surface deformation method aiming at each group of shell molded line response surface experiments;
3) Establishing a water ring vacuum pump calculation domain model, establishing a water ring vacuum pump calculation model aiming at each group of shell molded lines, and performing CFD calculation by adopting a VOF two-phase flow model to obtain extraction quantity;
4) Establishing a second-order response surface model of the water ring vacuum pump, and a quadratic polynomial regression equation of the pumping capacity;
5) Taking the maximum extraction amount as an optimization target, and establishing a new shell molded line based on the NURBS free-form surface deformation method;
6) And calculating isothermal compression efficiency corresponding to the new shell molded line.
Optionally, in step 1), an xoy rectangular coordinate system is established by taking the initial circular shell molded line as a research object, and the radius of the initial circular shell molded line is set as r 0 When the radius of the circular shell profile which coincides with the positive direction of the x axis rotates clockwise around the circle center, an included angle between the radius and the positive direction of the x axis is theta, when the circular shell profile rotates clockwise for one circle, the theta is changed from 0 to 360 degrees, the water ring vacuum pump shell profile is divided into 4 sections, namely a blade top clearance section (theta is from 225 to 315 degrees clockwise), an air suction section (theta is from 315 to 360 degrees clockwise to 45 degrees), an air compression section (theta is from 45 to 135 degrees clockwise) and an air exhaust section (theta is from 135 to 225 degrees), and 8 direct control points A are taken on the initial circular shell profile 1 、A 2 、A 3 、A 4 、A 5 、A 6 、A 7 、A 8 Corresponding theta is 0 degree, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees and 315 degrees respectively, and each direct control point is connected with a circleThe distance of the heart O, i.e. the radial value, is used as the control variable r i (i=1, 2, …) by controlling the variable r i The change of (2) realizes the molded line deformation of the water ring vacuum pump shell, and in order to ensure the stable operation of the blade top clearance section and the gas compression section, the corresponding control variable r with the theta of 270 DEG is adopted 7 And a control variable r corresponding to θ of 90 degrees 3 The deformation process of the shell molded line is kept unchanged, the rest control variables take 3 levels in the deformation process of the shell molded line, mu is set as deformation, wherein mu is a deformation coefficient set according to the eccentricity e of the water ring vacuum pump, namely r 1 、r 2 、r 4 、r 5 、r 6 、r 8 Designed with 3 levels, i.e. [ r ] 0 -μ*e，r 0 ，r 0 +μ*e]，r 3 、r 7 The 3 levels of design are equal, i.e. [ r ] 0 ，r 0 ，r 0 ]And designing an 8-factor 3 horizontal shell molded line response surface experiment based on a response surface method.
Optionally, in step 2), in order to ensure smooth connection of the shell-shaped line blade tip gap section, the air suction section, the air compression section and the air discharge section, NURBS (non-uniform rational B-spline curve) is used to express the shell-shaped line, and key elements of the NURBS curve include control vertices and weight factors; for each group of shell molded line response surface experiments, the shell molded line is subjected to parameterization deformation control based on NURBS free-form surface deformation method, and the initial shell molded line shape is flexibly changed by adjusting NURBS curve control peaks or weight factors, so that a direct control point A on the shell molded line is realized 1 、A 2 、A 3 、A 4 、A 5 、A 6 、A 7 、A 8 Radially moving to a desired position; and then, according to the adjusted NURBS curve control vertex or weight factor, calculating the position coordinates of other points on the shell type line, and further obtaining the deformed new shell type line.
Optionally, in step 3), for each new set of shell molded lines, a water ring vacuum pump calculation domain model including a shell, impeller blades, an air inlet, an air outlet, an end cover and a fluid supplementing port is built based on SolidWorks software, impeller rotation speed and air suction port pressure under rated working conditions of the water ring vacuum pump are set as boundary conditions, and CFD (computational fluid dynamics) calculation is performed by adopting a VOF gas-liquid two-phase flow model to obtain the water ring vacuum pump air pumping capacity.
Optionally, in step 4), r is used as r on the basis of step 1), step 2) and step 3) 1 、r 2 、r 3 、r 4 、r 5 、r 6 、r 7 、r 8 And (3) taking the extraction quantity Q as an output quantity for a control variable (namely an input variable), establishing a second-order response surface model, and establishing a quadratic polynomial regression equation of the extraction quantity.
Optionally, in step 5), for the second-order response surface model of the extraction quantity Q established in step 4), calculating the control variable r with the maximum extraction quantity as the optimization target 1 、r 2 、r 3 、r 4 、r 5 、r 6 、r 7 、r 8 According to step 2), a new shell molded line expressed by NURBS is obtained by a NURBS free-form surface deformation method, and the shell molded line consists of a blade top clearance section, an air suction section, a gas compression section and an air discharge section which are smoothly connected, and the optimal shell molded line corresponds to the highest isothermal compression efficiency eta of the water-ring vacuum pump because the isothermal compression efficiency of the water-ring vacuum pump is positively related to the air suction quantity under the condition that the impeller rotating speed and the air suction port pressure are kept unchanged.
η＝P is /P in *100％ (1)
P is ＝38.37P 1 *Q*lg(P 2 /P 1 ) (2)
P in ＝M*w/9550+P is (3)
Wherein P is 1 Is the pressure of the water ring vacuum pump suction, P 2 Is the pressure of the exhaust port of the water ring vacuum pump, Q is the extraction quantity, M is the torque of the pump shaft acting on the impeller, w is the angular velocity of the impeller, and P is Is isothermal compression power, P in Is the shaft power.
Compared with the prior art, the invention has the following technical effects:
the invention divides the molded line of the water-ring vacuum pump housing into 4 sections, and the direct control points cover all the blade top clearance sections, the air suction sections, the air compression sections and the air discharge sections in the design process of the molded line of the housing, and the designed high-efficiency molded line of the housing ensures the stable operation of the water-ring vacuum pump, reduces the flow loss and improves the pumping efficiency and isothermal compression efficiency of the water-ring vacuum pump. The invention adopts the high-efficiency shell molded line designed by the NURBS free-form surface deformation method, ensures the smooth connection of the shell molded line blade top gap section, the air suction section, the air compression section and the air discharge section, and further reduces the flow loss.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for designing a high-efficiency four-section NURBS shell molded line of a water ring vacuum pump;
FIG. 2 is a graph of direct control points on the water ring vacuum pump casing profile of the present invention;
FIG. 3 is a flow of the water ring vacuum pump housing molded line NURBS freeform surface deformation control of the present invention;
FIG. 4 is a flow chart of calculation of pumping capacity of a water ring vacuum pump;
fig. 5 is an efficient four-segment NURBS housing profile designed in an embodiment.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a water ring vacuum pump shell molded line design method, which is used for solving the problems in the prior art, dividing the water ring vacuum pump shell molded line into 4 sections, and realizing smooth connection of the designed high-efficiency shell molded line, ensuring the stable operation of the water ring vacuum pump, reducing the flow loss and improving the pumping efficiency and isothermal compression efficiency of the water ring vacuum pump.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
The invention provides a water ring vacuum pump shell molded line design method, which is shown in fig. 1,2, 3, 4 and 5 and comprises the following steps:
1) The method comprises the steps of setting shell molded lines in sections and control variables, and designing a four-section shell molded line response surface experiment of the 8 factor 3 horizontal water ring vacuum pump based on a response surface method; 2) Calculating a new shell molded line based on a NURBS free-form surface deformation method aiming at each group of shell molded line response surface experiments; 3) Establishing a water ring vacuum pump calculation domain model, establishing a water ring vacuum pump calculation model aiming at each group of shell molded lines, and performing CFD calculation by adopting a VOF two-phase flow model to obtain extraction quantity; 4) Establishing a second-order response surface model of the water ring vacuum pump, and a quadratic polynomial regression equation of the pumping capacity; 5) Taking the maximum extraction amount as an optimization target, and establishing a new shell molded line based on the NURBS free-form surface deformation method; 6) And calculating isothermal compression efficiency corresponding to the new shell molded line.
Further preferably, in step 1) of the present invention, an xoy rectangular coordinate system is established by taking an initial circular shell molded line as a research object, and the radius of the initial circular shell molded line is set as r 0 When the radius of the circular shell profile which coincides with the positive direction of the x axis rotates clockwise around the circle center, an included angle between the radius of the circular shell profile and the positive direction of the x axis is theta, when the circular shell profile rotates clockwise for one circle, the theta changes from 0 degree to 360 degrees, the water ring vacuum pump shell profile is divided into 4 sections, namely, a blade top clearance section theta changes from 225 degrees to 315 degrees, an air suction section theta changes from 315 degrees to 360 degrees and then changes from 45 degrees, a gas compression section theta changes from 45 degrees to 135 degrees and an air discharge section theta changes from 135 degrees to 225 degrees, and 8 direct control points A are taken on the initial circular shell profile 1 、A 2 、A 3 、A 4 、A 5 、A 6 、A 7 、A 8 Corresponding theta is 0 degree, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees and 315 degrees respectively, and each is directly controlledThe distance between the control point and the circle center O, namely the radial value, is taken as a control variable r i (i=1, 2, …) by controlling the variable r i The change of (2) realizes the molded line deformation of the water ring vacuum pump shell, and in order to ensure the stable operation of the blade top clearance section and the gas compression section, the corresponding control variable r with the theta of 270 DEG is adopted 7 And a control variable r corresponding to θ of 90 degrees 3 The deformation process of the shell molded line is kept unchanged, the rest control variables take 3 levels in the deformation process of the shell molded line, mu is set as deformation, wherein mu is a deformation coefficient set according to the eccentricity e of the water ring vacuum pump, namely r 1 、r 2 、r 4 、r 5 、r 6 、r 8 Designed with 3 levels, i.e. [ r ] 0 -μ*e，r 0 ，r 0 +μ*e]，r 3 、r 7 The 3 levels of design are equal, i.e. [ r ] 0 ，r 0 ，r 0 ]And designing an 8-factor 3 horizontal shell molded line response surface experiment based on a response surface method.
In the step 2), in order to ensure the smooth connection of the shell type line blade tip clearance section, the air suction section, the air compression section and the air discharge section, NURBS, namely a non-uniform rational B spline curve is used for expressing the shell type line, and key elements of the NURBS curve comprise control peaks and weight factors; for each group of shell molded line response surface experiments, the shell molded line is subjected to parameterization deformation control based on NURBS free-form surface deformation method, and the initial shell molded line shape is flexibly changed by adjusting NURBS curve control peaks or weight factors, so that a direct control point A on the shell molded line is realized 1 、A 2 、A 3 、A 4 、A 5 、A 6 、A 7 、A 8 Radially moving to a desired position; and then, according to the adjusted NURBS curve control vertex or weight factor, calculating the position coordinates of other points on the shell type line, and further obtaining the deformed new shell type line.
In the step 3), a water ring vacuum pump calculation domain model comprising a shell, impeller blades, an air inlet, an air outlet, an end cover and a fluid supplementing port is established based on SolidWorks software aiming at each group of new shell molded lines, the impeller rotating speed and the air inlet pressure under the rated working condition of the water ring vacuum pump are set as boundary conditions, and CFD (computational fluid dynamics) calculation is carried out by adopting a VOF gas-liquid two-phase flow model to obtain the water ring vacuum pump suction pump.
In the step 4), r is used as r on the basis of the steps 1), 2) and 3) 1 、r 2 、r 3 、r 4 、r 5 、r 6 、r 7 、r 8 For a control variable, namely an input variable, a second-order response surface model is built by taking the extraction quantity Q as an output quantity, and a quadratic polynomial regression equation of the extraction quantity is built:
Q＝β 0 +∑(i＝1,8)β i *r i +∑(i<j,8)β ij *r i *r j +∑(i＝1,8)β ii *r i *r i (1)
in step 5), aiming at the second-order response surface model of the extraction quantity Q established in step 4), calculating a control variable r by taking the maximum extraction quantity as an optimization target 1 、r 2 、r 3 、r 4 、r 5 、r 6 、r 7 、r 8 According to step 2), a new shell molded line expressed by NURBS is obtained by a NURBS free-form surface deformation method, and the shell molded line consists of a blade top clearance section, an air suction section, a gas compression section and an air discharge section which are smoothly connected, and the optimal shell molded line corresponds to the highest isothermal compression efficiency eta of the water-ring vacuum pump because the isothermal compression efficiency of the water-ring vacuum pump is positively related to the air suction quantity under the condition that the impeller rotating speed and the air suction port pressure are kept unchanged.
η＝P is /P in *100％ (2)
P is ＝38.37P 1 *Q*lg(P 2 /P 1 ) (3)
P in ＝M*w/9550+P is (4)
Wherein P is 1 Is the pressure of the water ring vacuum pump suction, P 2 Is the pressure of the exhaust port of the water ring vacuum pump, Q is the extraction quantity, M is the torque of the pump shaft acting on the impeller, w is the angular velocity of the impeller, and P is Is isothermal compression power, P in Is the shaft power.
Example 1
The embodiment uses the shell molded line of the 2BEA-703 type water ring vacuum pumpThe optimization design is verified by taking an example. 2BEA-703 water ring vacuum pump impeller radius 700mm, hub radius 343mm, eccentricity 90.5mm, 18 blades, impeller rated rotation speed 330r/min, suction pressure 400hpa, circular shell molded line adopted before optimization, radius 808mm, suction quantity 365m 3 The isothermal compression efficiency was 27.1%.
By adopting the design method, 8 direct control points A are selected 1 、A 2 、A 3 、A 4 、A 5 、A 6 、A 7 、A 8 As shown in fig. 2; setting a deformation coefficient mu as 0.27 according to the eccentricity of the water ring vacuum pump, setting the deformation quantity as 24.4mm, and designing an 8-factor 3 horizontal shell molded line response surface experimental model, wherein a control variable r 1 、r 2 、r 3 、r 4 、r 5 、r 6 、r 7 、r 8 The values of (2) are shown in Table 1.
Table 1 level of control variables in shell-type line response surface experiments
Based on the control variable r 1 、r 2 、r 3 、r 4 、r 5 、r 6 、r 7 、r 8 The designed shell profile response surface experiments are shown in table 2.
Table 2 design of experiments on the shell profile response surface
After a steady-state phase diagram is obtained by adopting a VOF gas-liquid two-phase flow model to carry out CFD calculation, the phase diagram is imported into CAD software and the drawing proportion is calculated, when the water ring boundary is tangential with the hub, the air suction amount is completely determined by the maximum chamber area of the air suction section, when the water ring boundary is not tangential with the hub, the equivalent air suction area is calculated according to the chamber areas of the air suction section and the air discharge section, the water ring vacuum pump suction area Q is calculated according to the impeller rotating speed and the impeller axial length, and the water ring vacuum pump suction area Q is filled into the table 2.
On the basis of the circular shell molded line of the 2BEA-703 type water ring vacuum pump, the optimized high-efficiency four-section NURBS shell molded line of the water ring vacuum pump is adopted, as shown in figure 5, the working stability of the water ring vacuum pump is ensured, the smooth connection of a blade top clearance section, an air suction section, a gas compression section and an air discharge section of the shell molded line is ensured, the flow loss is reduced, and the air suction quantity reaches 428m under the condition that the rated rotation speed and the air suction pressure of an impeller are unchanged 3 The time per minute is increased by 17.3 percent; the isothermal compression efficiency reaches 30.4%, and the improvement is 3.3%.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "top", "bottom", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The principles and embodiments of the present invention have been described in detail with reference to specific examples, which are provided to facilitate understanding of the method and core ideas of the present invention; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (6)
1. A water ring vacuum pump shell molded line design method is characterized in that: the method comprises the following steps:
1) The method comprises the steps of setting shell molded lines in sections and control variables, and designing a four-section shell molded line response surface experiment of the 8 factor 3 horizontal water ring vacuum pump based on a response surface method;
2) Calculating a new shell molded line based on a NURBS free-form surface deformation method aiming at each group of shell molded line response surface experiments;
3) Establishing a water ring vacuum pump calculation domain model, establishing a water ring vacuum pump calculation model aiming at each group of shell molded lines, and performing CFD calculation by adopting a VOF two-phase flow model to obtain extraction quantity;
4) Establishing a second-order response surface model of the water ring vacuum pump, and a quadratic polynomial regression equation of the pumping capacity;
5) Taking the maximum extraction amount as an optimization target, and establishing a new shell molded line based on the NURBS free-form surface deformation method;
6) And calculating isothermal compression efficiency corresponding to the new shell molded line.
2. The water ring vacuum pump housing profile design method of claim 1, wherein: in the step 1), an initial circular shell molded line is taken as a research object to establish an xoy rectangular coordinate system, and the radius of the initial circular shell molded line is set as r 0 When the radius of the circular shell molded line which coincides with the positive direction of the x axis rotates clockwise around the circle center, the included angle between the radius of the circular shell molded line and the positive direction of the x axis is theta, when the circular shell molded line rotates clockwise, the theta is changed from 0 degree to 360 degrees, the molded line of the water ring vacuum pump shell is divided into a blade top gap section, an air suction section, a gas compression section and an air discharge section, and 8 direct control points A are taken on the initial circular shell molded line 1 、A 2 、A 3 、A 4 、A 5 、A 6 、A 7 、A 8 Corresponding theta is 0 degree, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees and 315 degrees respectively, and the radial value which is the distance between each direct control point and the circle center O is taken as a control variable r i By controlling the variable r i The change of (2) realizes the molded line deformation of the water ring vacuum pump shell, and corresponds to a control variable r with the theta of 270 DEG 7 And a control variable r corresponding to θ of 90 degrees 3 The method is characterized in that the deformation process of the shell molded line is kept unchanged, the rest control variables are in 3 levels in the deformation process of the shell molded line, mu is set as deformation, mu is a deformation coefficient set according to the eccentricity e of the water ring vacuum pump, and an 8-factor 3-level shell molded line response surface experiment is designed based on a response surface method.
3. According to claimThe water ring vacuum pump housing molded line design method is characterized by comprising the following steps: in the step 2), NURBS is used for expressing the shell molded line, for each group of shell molded line response surface experiments, the shell molded line is subjected to parameterization deformation control based on a NURBS free-form surface deformation method, and the initial shell molded line shape is flexibly changed by adjusting the NURBS curve control vertex or weight factor, so that a direct control point A on the shell molded line is realized 1 、A 2 、A 3 、A 4 、A 5 、A 6 、A 7 、A 8 Radially moving to a desired position; and then, according to the adjusted NURBS curve control vertex or weight factor, calculating the position coordinates of other points on the shell type line, and further obtaining the deformed new shell type line.
4. The water ring vacuum pump housing profile design method of claim 1, wherein: in the step 3), a water ring vacuum pump calculation domain model comprising a shell, impeller blades, an air inlet, an air outlet, an end cover and a fluid supplementing port is established based on software aiming at each group of new shell molded lines, the impeller rotating speed and the air inlet pressure under the rated working condition of the water ring vacuum pump are set as boundary conditions, and the CFD calculation is carried out by adopting the VOF gas-liquid two-phase flow model to obtain the water ring vacuum pump air pumping capacity.
5. The water ring vacuum pump housing profile design method of claim 1, wherein: in the step 4), r is used as r on the basis of the steps 1), 2) and 3) 1 、r 2 、r 3 、r 4 、r 5 、r 6 、r 7 、r 8 And (3) taking the extraction quantity Q as an output quantity for controlling the variable, establishing a second-order response surface model, and establishing a quadratic polynomial regression equation of the extraction quantity.
6. The water ring vacuum pump housing profile design method of claim 1, wherein: in step 5), aiming at the second-order response surface model of the extraction quantity Q established in step 4), calculating a control variable r by taking the maximum extraction quantity as an optimization target 1 、r 2 、r 3 、r 4 、r 5 、r 6 、r 7 、r 8 The method comprises the steps of carrying out a first treatment on the surface of the According to step 2), a new shell molded line expressed by NURBS is obtained by a NURBS free-form surface deformation method, the shell molded line is formed by smoothly connecting a blade top clearance section, an air suction section, a gas compression section and an air discharge section, and the shell molded line corresponds to the highest isothermal compression efficiency eta of the water-ring vacuum pump:
η＝P is /P in *100％ (1)
P is ＝38.37P 1 *Q*lg(P 2 /P 1 ) (2)
P in ＝M*w/9550+P is (3)
wherein P is 1 Is the pressure of the water ring vacuum pump suction, P 2 Is the pressure of the exhaust port of the water ring vacuum pump, Q is the pumping speed of the water ring vacuum pump, M is the torque of the pump shaft acting on the impeller, w is the angular speed of the impeller, and P is Is isothermal compression power, P in Is the shaft power.
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| CN107515996A (en) * | 2017-09-27 | 2017-12-26 | 西安理工大学 | A kind of Optimization Design of darrieus hydraulic turbine kuppe molded line |
| CN110750855A (en) * | 2019-09-06 | 2020-02-04 | 华中科技大学 | Volute molded line design method under shape sizing limitation |
| CN113505435A (en) * | 2021-07-01 | 2021-10-15 | 青岛澎湃海洋探索技术有限公司 | Carbon fiber shell analysis method based on response surface model |
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| CN107515996A (en) * | 2017-09-27 | 2017-12-26 | 西安理工大学 | A kind of Optimization Design of darrieus hydraulic turbine kuppe molded line |
| CN110750855A (en) * | 2019-09-06 | 2020-02-04 | 华中科技大学 | Volute molded line design method under shape sizing limitation |
| CN113505435A (en) * | 2021-07-01 | 2021-10-15 | 青岛澎湃海洋探索技术有限公司 | Carbon fiber shell analysis method based on response surface model |
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| "利用VOF模型模拟水环真空泵的气液两相流";郑志富等;《真空科学与技术学报》;第第42卷卷(第第2期期);139-144 * |
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