CN109606599B - Magnetic drive water jet propulsion pump with impeller with small hub ratio - Google Patents
Magnetic drive water jet propulsion pump with impeller with small hub ratio Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H11/00—Marine propulsion by water jets
- B63H11/02—Marine propulsion by water jets the propulsive medium being ambient water
- B63H11/04—Marine propulsion by water jets the propulsive medium being ambient water by means of pumps
- B63H11/08—Marine propulsion by water jets the propulsive medium being ambient water by means of pumps of rotary type
Abstract
The invention belongs to the field of fluid machinery, and particularly relates to a magnetic drive water jet propulsion pump with an impeller with a small hub ratio. The small hub ratio impeller designed by the invention has reasonable structure and excellent hydraulic performance, and under the condition that the flow and the lift meet the requirements of design working conditions, the hub is reduced by about 64 percent, the outer diameter of the impeller is reduced by about 13 percent, and the flow capacity of the impeller is obviously improved.
Description
Technical Field
The invention belongs to the field of fluid machinery, and particularly relates to a magnetic drive water jet propulsion pump with an impeller with a small hub ratio.
Background
The traditional water jet propulsion pump adopts single-stage impeller transmission, and a motor and a transmission part are arranged around the outer part of a shell. Therefore, the flow capacity and the work capacity of the water jet propulsion pump are low; and the motor and the transmission part are difficult to install, and the sealing performance is poor, so that the service life of the water jet propulsion pump is short, the failure rate is high, and the efficiency is reduced.
In addition, the outer diameters of the hub and the impeller of the traditional water jet propulsion pump are large, the size and the weight are correspondingly large, the flow capacity of the impeller is poor, and the hydraulic efficiency is low.
Disclosure of Invention
In order to solve the above problems, the present invention provides a magnetically driven water jet propulsion pump having an impeller with a small hub ratio, in which the hub and the outer diameter of the impeller are both small, thereby greatly improving the flow capacity of the impeller.
The invention provides the following technical scheme:
a magnetic drive water jet propulsion pump with an impeller with a small hub ratio comprises two groups of impeller assemblies coaxially arranged in a pump cavity, wherein the two groups of impeller assemblies are arranged oppositely, each group of impeller assembly comprises an impeller shaft, a guide vane fixed on the impeller shaft and an impeller arranged on the impeller shaft through a bearing, and the impeller is an impeller with a small hub ratio.
Preferably, the centrifugal pump further comprises a pump shell, a stator assembly, an isolation sleeve and a rotor assembly, wherein the stator assembly, the isolation sleeve and the rotor assembly are located inside the pump shell, the pump shell is formed by installing a left shell, a cylindrical middle shell and a right shell which are sequentially arranged along the axial direction of the impeller, guide vanes in the first group of impeller assemblies are far away from the second group of impeller assemblies and are fixed with the left shell, guide vanes in the second group of impeller assemblies are fixed with the right shell, and the rotor assembly is arranged at the rim of the small hub which is closer to the impeller.
Preferably, the isolation sleeve is positioned on the inner side of the middle shell, one end of the isolation sleeve is in sealing connection with the left shell, the other end of the isolation sleeve is in sealing connection with the right shell to form a pump cavity, the stator assembly is installed on the outer side of the isolation sleeve, and the rotor assembly is installed on the inner side of the isolation sleeve;
the left shell is provided with a water inlet, the right shell is provided with a water outlet, and the water inlet and the water outlet are coaxially arranged with the impeller shaft;
the guide vanes in the first group of impeller assemblies are welded with the impeller shaft in the first group of impeller assemblies and the left shell into a whole; the guide vanes in the second group of impeller assemblies, the impeller shafts in the second group of impeller assemblies and the right shell are welded into a whole;
the inner wall of the left shell is provided with a step for inserting one end of the isolation sleeve, and the inner wall of the right shell is provided with a step for inserting the other end of the isolation sleeve.
Preferably, the method for designing the impeller with the small hub ratio comprises the following steps:
s1, obtaining the outer diameter D of the impeller with the small hub ratio;
s2, determining the number of blades and the blade airfoil of the impeller with the small hub ratio;
s3, obtaining the edge blade cascade of the impeller with small hub ratioDensity syAnd blade row density s at the hubg；
S4, dividing blades of the impeller with the small hub ratio into m cylindrical sections in an equidistant mode, sequentially marking the cylindrical sections as 1-1, 2-2, … … and m-m from the hub to the edge, and respectively obtaining an airfoil arrangement angle β of each cylindrical sectionL；
S5 for airfoil setting angle β in S4LCorrecting the value of (A);
s6, determining the blade thickness of the impeller with the small hub ratio;
s7, modeling parameters of the impeller with the small hub ratio obtained in the S1-S6, carrying out numerical simulation on the established impeller model to obtain a simulation lift value, and if the simulation lift value is within the range of the design lift value, completing the design of the impeller with the small hub ratio;
and if the simulation lift value is out of the design lift value range, switching to S1 for recalculation until the simulation lift value is in the design lift value range.
Preferably, the specific step of S1 includes:
s11, obtaining the estimated value D of the outer diameter of the impeller with the small hub ratio by the following formulaEstimated value,
Wherein n is the motor rotation speed, pi is the circumference ratio, nsThe specific rotating speed of the rim driving pump, and H is the lift;
s12, obtaining the small hub ratio impeller hub diameter d through the following formula,
d＝Rd*Destimated value
Wherein R isdAs a hub ratio, DEstimated valueThe estimated value of the outer diameter of the small hub ratio impeller obtained in S11;
s13, obtaining the actual value D of the outer diameter of the impeller with the small hub ratio by the following formula,
wherein Q is the flow, n is the motor speed, pi is the circumferential rate, and d is the diameter of the impeller hub with the small hub ratio obtained in S12.
Preferably, the number of the blades in the S2 is 3-5, and the airfoil profile of the blade is an NACA series airfoil profile;
the actual value D of the small hub ratio impeller outer diameter obtained in S13 is checked by the following equation:
if D isCheckingWithin 0.1-0.3, is within the range of small hub ratios, if DCheckingOutside of 0.1-0.3, the outer diameter D of the impeller with a small hub ratio is retrieved through S11-S13.
Preferably, the specific step of S3 includes:
s31, obtaining the density S of the blade cascade at the wheel edge through the following formulay，
sy＝6.1751k+0.01254
Wherein the content of the first and second substances,
nsthe specific speed of the rim driven pump;
s32, obtaining the blade cascade density S at the hub through the following formulag，
sg＝(1.7～2.1)sy
Preferably, the specific step of S4 includes:
s41, obtaining the inlet setting angle β of each cylindrical section through the following formula1and outlet setting angle beta2，
wherein, beta1' is the inlet flow angle of the liquid,
u is the peripheral speed, vmIs the flow velocity of the axial surface of the inlet of the blade,
is the coefficient of blade displacement, pi is the circumferential ratio, ηvfor pump volumetric efficiency, D is the outer diameter of the impeller with small hub ratio, D is the hub diameter of the impeller with small hub ratio, and Delta beta1β being the angle of attack of the inlet2' is the outlet flow angle,
vu2being the component of the absolute velocity in the circumferential direction,
ηhis the hydraulic efficiency of the pump, xi is the correction coefficient, g is the gravitational acceleration, H is the lift, Delta beta2An exit attack angle;
s42, obtaining the airfoil arrangement angle β of each cylindrical section through the following formulaL，
βL＝(β1+β2)/2
Preferably, the specific process of correcting in S5 is as follows:
respectively obtaining the inlet setting angles β of the m cylindrical sections through the formula in S411is selected to be closest to the rim, and the cross-sectional diameters of the three cylindrical sections closest to the rim and the corresponding inlet seating angles beta are selected1Fitting the values of (a) to obtain the following quadratic polynomial:
y1＝a1x2+b1x+c1
wherein, y1setting an angle beta for the inlet1X is the diameter of the cross section of the cylinder, a1、b1And c1Are all constant and are all provided with the same power,
respectively substituting the cross-sectional diameters of the 1 st to the m-th cylindrical cross-sections into the secondary multi-sectionobtaining the corrected inlet installation angle β of the 1 st to the m th cylindrical sections by using the polynomial1A value of (d);
the outlet setting angles β of the m cylindrical sections are respectively obtained by the formula in S412is selected to be closest to the rim, the cross-sectional diameter of the three cylindrical sections closest to the rim and the corresponding outlet seating angle beta2Fitting the values of (a) to obtain the following quadratic polynomial:
y2＝a2x2+b2x+c2
wherein, y2setting an angle beta for the outlet2X is the diameter of the cross section of the cylinder, a2、b2And c2Are all constant and are all provided with the same power,
respectively substituting the section diameters of the 1 st to the mth cylindrical sections into the quadratic polynomial to obtain the outlet setting angles β of the 1 st to the mth cylindrical sections after being corrected2The value of (a) is,
setting the corrected inlet setting angle beta1and outlet setting angle beta2substituting the formula in S42 to obtain the corrected airfoil setting angle β of each cylindrical sectionLThe value of (c).
Preferably, in S6, the blade thickness is smaller under the condition of satisfying the requirement of mechanical strength, the blade thickness at the wheel rim is 2 to 4 times of the blade thickness at the wheel hub, and the blade thickness in the rest part is changed in a uniform and smooth transition manner.
The invention has the beneficial effects that:
1. the magnetic drive water jet propulsion pump is different from the structure of the traditional magnetic drive water jet propulsion pump, a double-stage impeller assembly is adopted in the magnetic drive water jet propulsion pump, and when two impellers rotate in the same direction at the same time, the water jet propulsion pump has double power, so that the overcurrent capacity is improved; when the two impellers do not rotate simultaneously, the impeller which does not rotate has the functions of rectifying and stabilizing the flow field in the pump cavity; when the two impellers rotate in opposite directions simultaneously, the ship can be in a static state.
The invention has simple assembly mode and good sealing effect. The invention is assembled: the guide vane and the impeller are installed on the impeller shaft to complete installation of the impeller assembly, the first impeller assembly is fixed with the left shell through the guide vane, the second impeller assembly is fixed with the right shell through the guide vane, then the isolation sleeve is in sealing connection with the left shell and the right shell, then the stator assembly is installed on the outer side of the isolation sleeve, and finally the middle shell is fixed with the left shell and the right shell respectively to complete installation.
2. According to the impeller pump, the left shell is provided with the water inlet, the right shell is provided with the water outlet, and the water inlet, the water outlet and the impeller shaft are coaxially arranged.
3. In order to facilitate installation, the guide vanes in the first group of impeller assemblies, the impeller shafts in the first group of impeller assemblies and the left shell are welded into a whole, and the guide vanes in the second group of impeller assemblies, the impeller shafts in the second group of impeller assemblies and the right shell are welded into a whole. When the impeller assembly is installed, the impeller assembly can be installed on the impeller shaft only by installing the corresponding impeller through the bearing, then the isolation sleeve is hermetically connected with the left shell and the right shell, then the stator assembly is installed on the outer side of the isolation sleeve, and finally the middle shell is respectively fixed with the left shell and the right shell, so that the installation is completed.
4. The inner walls of the left shell and the right shell can be semi-ellipsoidal, the left shell and the right shell are respectively provided with a step, an O-shaped sealing ring is placed in each step during installation, and two ends of the isolation sleeve are respectively inserted into the steps in the left shell and the right shell, so that the connection tightness is greatly improved, and the installation mode is more convenient.
5. The small hub ratio impeller designed by the invention has reasonable structure and excellent hydraulic performance, and under the condition that the flow and the lift meet the requirements of design working conditions, the hub is reduced by about 64 percent, the outer diameter of the impeller is reduced by about 13 percent, and the flow capacity of the impeller is obviously improved.
Drawings
FIG. 1 is a schematic diagram of a magnetically driven water jet propulsion pump;
FIG. 2 is a schematic structural view of a small hub ratio impeller blade;
FIG. 3 is a three-dimensional view of a small hub ratio impeller blade;
FIG. 4 is a flow Q-head H curve and a flow Q-efficiency η curve of a numerical simulation of a small hub ratio impeller;
FIG. 5 is a velocity flow diagram of a numerical simulation of a low hub ratio impeller;
FIG. 6 is a total pressure profile at a mid-section of an impeller blade;
fig. 7A is a comparison of small hub ratio impeller head to model experimental head results;
figure 7B is a comparison of the low hub ratio impeller efficiency and the model experiment efficiency results.
The designations in the drawings have the following meanings:
111-left casing 112-middle casing 113-right casing 12-stator assembly 13-spacer sleeve 14-rotor assembly 151-hub 152-guide vane 153-impeller 154-bearing 155-nut a-water inlet b-water outlet
Detailed Description
The present invention will be described in detail with reference to the following examples.
Example 1
As shown in fig. 1, the pump comprises two sets of impeller assemblies coaxially arranged in a pump cavity, wherein the two sets of impeller assemblies are arranged oppositely, each set of impeller assembly comprises an impeller shaft 151, a guide vane 152 fixed on the impeller shaft 151 and an impeller 153 installed on the impeller shaft 151 through a bearing 154, and the impeller is a small hub ratio impeller.
Example 2
As shown in fig. 1, on the basis of embodiment 1, the magnetically driven water jet propulsion pump further includes a pump casing, a stator assembly 12, an isolation sleeve 13, and a rotor assembly 14, the pump casing is formed by installing a left casing 111, a cylindrical middle casing 112, and a right casing 113, which are sequentially arranged along an impeller axial direction, wherein guide vanes in the first group of impeller assemblies are far away from the second group of impeller assemblies and fixed with the left casing 111, guide vanes in the second group of impeller assemblies are fixed with the right casing 113, and the rotor assembly is disposed at a rim of a small hub than the impeller.
Example 3
As shown in fig. 1, on the basis of embodiment 2, the separation sleeve 13 is located inside the middle housing 112, one end of the separation sleeve 13 is hermetically connected with the left housing 111, and the other end of the separation sleeve 13 is hermetically connected with the right housing 113 and forms a pump chamber, the stator assembly 12 is installed outside the separation sleeve 13, and the rotor assembly 14 is installed inside the separation sleeve 13;
the left shell 111 is provided with a water inlet a, the right shell 113 is provided with a water outlet b, and the water inlet a and the water outlet b are coaxially arranged with the impeller shaft 151;
the vanes 152 of the first set of impeller assemblies are welded to the impeller shaft 151 of the first set of impeller assemblies and to the left casing 111; the guide vanes 152 in the second set of impeller assemblies are welded with the impeller shaft 11 in the second set of impeller assemblies and the right casing 113 as a whole;
the inner wall of the left shell 111 is provided with a step for inserting one end of the isolation sleeve 13, and the inner wall of the right shell 113 is provided with a step for inserting the other end of the isolation sleeve 13.
Example 4
On the basis of any one of embodiments 1 to 3, the hydraulic design parameters of the small hub ratio impeller design of a certain magnetic drive water jet propulsion pump are as follows: head H2 m, flow Q270 m3H, the motor speed n is 1450r/min, the specific speed ns＝862。
S1, obtaining the outer diameter D of the impeller with the small hub ratio;
s11, obtaining the estimated value D of the outer diameter of the impeller with the small hub ratio by the following formulaEstimated value,
Estimated outer diameter D of impellerEstimated valueTaking the integer of 188mm as the reference,
s12, obtaining the small hub ratio impeller hub diameter d through the following formula,
d＝Rd*Destimated value＝37.6mm
The hub diameter d is 38mm in integer.
S13, obtaining the actual value D of the outer diameter of the impeller with the small hub ratio by the following formula,
the actual value D of the outer diameter of the impeller with small hub ratio is 164mm in integer
Checking the external dimension of the impeller by the following formula:
d is 164mmh38mm as a parameter for the basic pump size, Rd＝dh/D20.232, between 0.1 and 0.3, falls within the range of small hub ratios.
S2, determining the number of blades and the blade airfoil of the impeller with the small hub ratio;
the phenomenon of squeezing fluid by the blades at the hub is obviously aggravated by the excessive number of the blades of the impeller with small hub ratio, the number of the blades is determined to be 3-5, and the blade is rotated with the specific speed nsIs increased and decreased. The specific speed n of the pump of the embodimentsAnd the number of blades belongs to an intermediate specific speed interval, so that 4 blades are counted, and the blade airfoil adopts an NACA4406 series airfoil.
S3, obtaining the blade cascade density S at the edge of the impeller with small hub ratioyAnd blade row density s at the hubg；
S31, obtaining the density S of the blade cascade at the wheel edge through the following formulay，
sy＝6.1751k+0.01254
Wherein the content of the first and second substances,
through calculation, sy＝0.8153，
When a small-hub impeller is designed by using a traditional design method, the impeller is seriously twisted near the hub, the chord length is too small, and even the situation that the direction of the fluid flowing out of the hub is opposite to the main flow direction occurs, so that the blade cannot be designed. Therefore, the conventional calculation formula needs to be corrected. The general correction strategy is to increase the chord length of the impeller near the hub, increase the density of the blade cascade at the hub by a proper amount and increase the outlet lift near the hub under the condition of not causing too serious displacement.
S32, obtaining the blade cascade density S at the hub through the following formulag，
sg＝(1.7～2.1)sy
Wherein s isgWhen the specific rotating speed is high, the value is large,
for the present embodiment, sg＝1.7sy，sg＝1.3859。
The density of the blade cascade at other positions is uniformly increased from the wheel rim to the wheel hub according to a linear change rule.
S4, dividing blades of the impeller with the small hub ratio into m cylindrical sections in an equidistant mode, sequentially marking the cylindrical sections as 1-1, 2-2, … … and m-m from the hub to the edge, and respectively obtaining an airfoil arrangement angle β of each cylindrical sectionL；
S41, obtaining the inlet setting angle β of each cylindrical section through the following formula1and outlet setting angle beta2，
wherein β'1Is an inlet liquid flow angle and is characterized in that,
u is the peripheral speed, vmIs the flow velocity of the axial surface of the inlet of the blade,
is the coefficient of blade displacement, pi is the circumferential ratio, ηvFor pump volumetric efficiency, D is smallthe outer diameter of the impeller with hub ratio, d is the diameter of the impeller with small hub ratio, delta β1β being the angle of attack of the inlet2' is the outlet flow angle,
vu2being the component of the absolute velocity in the circumferential direction,
ηhis the hydraulic efficiency of the pump, xi is the correction coefficient, g is the gravitational acceleration, H is the lift, Delta beta2An exit attack angle;
s42, obtaining the airfoil arrangement angle β of each cylindrical section through the following formulaL
βL＝(β1+β2)/2
the inlet seating angles β of the first to mth cylindrical sections are obtained by the formula in S411is selected to be closest to the rim, and the cross-sectional diameters of the three cylindrical sections closest to the rim and the corresponding inlet seating angles beta are selected1Fitting the values of (a) to obtain the following quadratic polynomial:
y1＝a1x2+b1x+c1
wherein, y1setting an angle beta for the inlet1X is the diameter of the cross section of the cylinder, a1、b1And c1Is a constant number of times, and is,
respectively substituting the diameters of the cross sections of the first to the mth cylindrical cross sections into the quadratic polynomial to obtain the corrected inlet placement angles β of the first to the mth cylindrical cross sections1A value of (d);
the outlet setting angles β of the first to m-th cylindrical sections are obtained by the formula in S412is selected to be closest to the rim, the cross-sectional diameter of the three cylindrical sections closest to the rim and the corresponding outlet seating angle beta2Fitting the values of (a) to obtain the following quadratic polynomial:
y2＝a2x2+b2x+c2
wherein, y2setting an angle beta for the outlet2X is a circleCross-sectional diameter of column section, a2、b2And c2Is a constant number of times, and is,
respectively substituting the diameters of the first to the mth cylindrical sections into the quadratic polynomial to obtain the corrected outlet placement angles β of the first to the mth cylindrical sections2The value of (a) is,
the corrected inlet placement angle β described above is substituted by the formula in S421and outlet setting angle beta2obtaining corrected airfoil lay-up angles beta of the cylindrical sectionsLThe value of (c).
The value of m in this example is 7,
the inlet seating angle β of each cylindrical section is obtained by the formula in S411Wherein section 1-1 is 57.83, section 2-2 is 44.90, section 3-3 is 36.31, section 4-4 is 30.54, section 5-5 is 26.57, section 6-23.78, section 7-7 is 21.83;
selecting inlet placement angles β for sections 4-4, 5-5 and 6-61Is a dependent variable y, the section diameter of the corresponding section is an independent variable x, fitting is carried out to obtain the following formula,
y＝59.25-0.38x+0.00095x2
the inlet setting angle beta of each cylindrical section according to the formula1Correcting the value of (a) to obtain a corrected value, wherein the section 1-1 is 46.05, the section 2-2 is 39.93, the section 3-3 is 34.64, the section 4-4 is 30.19, the section 5-5 is 26.57, the section 6-6 is 23.78, and the section 7-7 is 21.83;
the outlet setting angle β of each cylindrical section is obtained by the formula in S412Wherein the section 1-1 is-46.56, the section 2-2 is-85.37, the section 3-3 is 61.96, the section 4-4 is-43.99, the section 5-5 is 34.14, the section 6-6 is 28.18, and the section 7-7 is 24.30;
selecting outlet placement angles β for sections 4-4, 5-5 and 6-62Is a dependent variable y, the section diameter of the corresponding section is an independent variable x, fitting is carried out to obtain the following formula,
y＝109.89-0.91x+0.0024x2
for each cylinder section according to the above formulaoutlet setting angle beta2The value of (a) is corrected to obtain a corrected value, wherein the section 1-1 is 48.77, the section 2-2 is 64.49, the section 3-3 is 52.30, the section 4-4 is 42.18, the section 5-5 is 34.14, the section 6-6 is 28.18, and the section 7-7 is 24.30;
the corrected inlet placement angle β described above is substituted by the formula in S421and outlet setting angle beta2obtaining corrected airfoil lay-up angles beta of the cylindrical sectionsLWherein the value of (1) is 62.41 for the section 1-1, 52.21 for the section 2-2, 43.37 for the section 3-3, 36.19 for the section 4-4, 30.36 for the section 5-5, 25.98 for the section 6-6, 23.07 for the section 7-7
S6, determining the blade thickness of the impeller with the small hub ratio;
the blade maximum thickness at the wheel edge is 10mm, and the blade maximum thickness at the wheel hub is 5mm, and the thickening is carried out according to the NACA4406 airfoil profile.
S7, verifying the method by adopting a Computational Fluid Dynamics (CFD) technology, and firstly, carrying out two-position design on the small hub ratio impeller hydraulic model designed according to the design method in a computer-aided design (CAD); secondly, guiding the designed hydraulic model into three-dimensional design software to generate a three-dimensional impeller entity (as shown in figure 3), and further processing on the basis to obtain a three-dimensional calculation water body; thirdly, the processed model is led into meshing software ANSYS ICEM for meshing; and finally, performing numerical simulation by using fluid mechanics analysis software ANSYS CFX or ANSYS FLUENT and the like, wherein the calculation method and the boundary condition are set as follows
The method is characterized in that a finite volume method is adopted to disperse a three-dimensional incompressible fluid control equation, and the control equation of three-dimensional turbulence numerical simulation comprises a cavitation model based on a two-phase flow mixing model, a Reynolds time average (RANS) Navier-Stokes (N-S) equation and an SST k-omega (shear stress transport) turbulence model more suitable for fluid separation. The control equation dispersion adopts a control volume method, an equation diffusion term is in a central difference format, and a convection term is in a second-order windward format. The equation solution adopts a separation semi-implicit pressure coupling algorithm. The inlet boundary condition adopts total pressure inlet, the outlet boundary condition adopts mass flow outlet, and the wall function adopts non-slipThe wall surface has a reference pressure of 0Pa, the energy transmission between the rotating member (impeller) and the stationary member (guide vane) is performed by a Frozen Rotor method, and the calculation convergence criterion is set to 10-5The medium is 25 degrees of water.
And (4) analyzing a calculation result:
FIG. 4 is a flow Q-lift H curve and a flow Q-efficiency η curve of a numerical simulation of an impeller with a small hub ratio, which can be obtained from the graph, wherein the lift of the pump is 2.05m under a design condition, and the numerical simulation result and the design lift H are obtaineddesCompared with 2m, the error is 2.5%, and the error is within the allowable range of engineering error, and the accuracy of the design method is verified.
Fig. 5 is a velocity flow diagram of numerical simulation of an impeller with a small hub ratio, and it can be seen from the figure that the water flow is relatively uniform before entering the impeller, the water continuously rotates to do work after passing through the impeller rotating at a high speed, and the water flow shows a spiral motion near the outlet under the influence of the rotation of the impeller. In general, no obvious secondary reflux phenomenon exists, and the flowing effect of water is better.
Fig. 6 is a total pressure distribution diagram at the middle section of the impeller blade, and it can be seen from the diagram that under the influence of the rotation of the blade, a low-pressure area is uniformly distributed at the inlet of the blade, and the pressure distribution at the outlet of the blade is relatively uniform.
In order to further verify the accuracy of the method, the numerical simulation result and the model experiment result are compared and analyzed. From fig. 7A, 7B, it can be derived that at the design operating point, the experimental head H of the pumpexpThe numerical simulation result is compared with the model experiment with an error of 1.99 percent when the value is 2.01 m. The comparison of the efficiency curves can result in a numerical simulation efficiency of 84.5%, a model experiment efficiency of 80.7% and an error of only 4.7%. Therefore, the impeller obtained by the design method of the impeller with the small hub ratio can completely meet the design requirement, and meanwhile, the accuracy of the method is verified.
Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (3)
1. The magnetic drive water jet propulsion pump with the impeller with the small hub ratio is characterized by comprising two groups of impeller assemblies which are coaxially arranged in a pump cavity, wherein the two groups of impeller assemblies are arranged oppositely, each group of impeller assembly comprises an impeller shaft (151), a guide vane (152) fixed on the impeller shaft (151) and an impeller (153) arranged on the impeller shaft (151) through a bearing (154), and the impeller is the impeller with the small hub ratio;
the design method of the impeller with the small hub ratio comprises the following steps:
s1, obtaining the outer diameter D of the impeller with the small hub ratio;
s2, determining the number of blades and the blade airfoil of the impeller with the small hub ratio;
s3, obtaining the blade cascade density S at the edge of the impeller with small hub ratioyAnd blade row density s at the hubg；
S4, dividing blades of the impeller with the small hub ratio into m cylindrical sections in an equidistant mode, sequentially marking the cylindrical sections as 1-1, 2-2, … … and m-m from the hub to the edge, and respectively obtaining an airfoil arrangement angle β of each cylindrical sectionL；
S5 for airfoil setting angle β in S4LCorrecting the value of (A);
s6, determining the blade thickness of the impeller with the small hub ratio;
s7, modeling parameters of the impeller with the small hub ratio obtained in the S1-S6, carrying out numerical simulation on the established impeller model to obtain a simulation lift value, and if the simulation lift value is within the range of the design lift value, completing the design of the impeller with the small hub ratio;
if the simulation lift value is out of the design lift value range, the simulation lift value is shifted to S1 for recalculation until the simulation lift value is in the design lift value range;
the specific steps of S1 include:
s11 byThe estimated value D of the outer diameter of the impeller with the small hub ratio is obtained by the following formulaEstimated value,
Wherein n is the motor rotation speed, pi is the circumference ratio, nsThe specific rotating speed of the rim driving pump, and H is the lift;
s12, obtaining the small hub ratio impeller hub diameter d through the following formula,
d＝Rd*Destimated value
Wherein R isdAs a hub ratio, DEstimated valueThe estimated value of the outer diameter of the small hub ratio impeller obtained in S11;
s13, obtaining the actual value D of the outer diameter of the impeller with the small hub ratio by the following formula,
wherein Q is flow, n is motor speed, pi is circumferential rate, and d is the diameter of the impeller hub with the small hub ratio obtained in S12;
the number of the blades in the S2 is 3-5, and the airfoil profile of each blade is an NACA series airfoil profile;
the actual value D of the small hub ratio impeller outer diameter obtained in S13 is checked by the following equation:
if D isCheckingWithin 0.1-0.3, is within the range of small hub ratios, if DCheckingOutside of 0.1-0.3, the outer diameter D of the impeller with a small hub ratio is obtained again through S11-S13;
the specific steps of S3 include:
s31, obtaining the density S of the blade cascade at the wheel edge through the following formulay，
sy＝6.1751k+0.01254
Wherein the content of the first and second substances,
k＝-5.0162×10-11×ns 3+3.04657×10-7×ns 2-6.32312×10-4×ns+0.4808
nsthe specific speed of the rim driven pump;
s32, obtaining the blade cascade density S at the hub through the following formulag，
sg＝(1.7～2.1)sy
The specific steps of S4 include:
s41, obtaining the inlet setting angle β of each cylindrical section through the following formula1and outlet setting angle beta2，
wherein, beta1' is the inlet flow angle of the liquid,
u is the peripheral speed, vmIs the flow velocity of the axial surface of the inlet of the blade,
is the coefficient of blade displacement, pi is the circumferential ratio, ηvfor pump volumetric efficiency, D is the outer diameter of the impeller with small hub ratio, D is the hub diameter of the impeller with small hub ratio, and Delta beta1β being the angle of attack of the inlet2' is the outlet flow angle,
vu2being the component of the absolute velocity in the circumferential direction,
ηhis the hydraulic efficiency of the pump, ξ is a correction coefficient, and g isacceleration of gravity, H being lift, delta beta2An exit attack angle;
s42, obtaining the airfoil arrangement angle β of each cylindrical section through the following formulaL，
βL＝(β1+β2)/2
The specific process of correction in S5 is as follows:
respectively obtaining the inlet setting angles β of the m cylindrical sections through the formula in S411is selected to be closest to the rim, and the cross-sectional diameters of the three cylindrical sections closest to the rim and the corresponding inlet seating angles beta are selected1Fitting the values of (a) to obtain the following quadratic polynomial:
y1＝a1x2+b1x+c1
wherein, y1setting an angle beta for the inlet1X is the diameter of the cross section of the cylinder, a1、b1And c1Are all constant and are all provided with the same power,
respectively substituting the section diameters of the 1 st to the mth cylindrical sections into the quadratic polynomial to obtain the corrected inlet placement angles β of the 1 st to the mth cylindrical sections1A value of (d);
the outlet setting angles β of the m cylindrical sections are respectively obtained by the formula in S412is selected to be closest to the rim, the cross-sectional diameter of the three cylindrical sections closest to the rim and the corresponding outlet seating angle beta2Fitting the values of (a) to obtain the following quadratic polynomial:
y2＝a2x2+b2x+c2
wherein, y2setting an angle beta for the outlet2X is the diameter of the cross section of the cylinder, a2、b2And c2Are all constant and are all provided with the same power,
respectively substituting the section diameters of the 1 st to the mth cylindrical sections into the quadratic polynomial to obtain the outlet setting angles β of the 1 st to the mth cylindrical sections after being corrected2The value of (a) is,
setting the corrected inlet setting angle beta1and outlet setting angle beta2Substituting into the formula in S42 to obtain the corrected airfoil setting angle of each cylindrical sectionβLA value of (d);
the thickness of the blade in the S6 is smaller under the condition of meeting the requirement of mechanical strength, the thickness of the blade at the wheel edge is 2-4 times of that of the blade at the wheel hub, and the thickness of the blade at the rest part is changed in a uniform and smooth transition mode.
2. The magnetic drive water jet propulsion pump with the impeller with the small hub ratio is characterized by further comprising a pump shell, a stator assembly (12), an isolation sleeve (13) and a rotor assembly (14), wherein the stator assembly, the isolation sleeve and the rotor assembly are positioned inside the pump shell, the pump shell is formed by installing a left shell (111), a cylindrical middle shell (112) and a right shell (113) which are sequentially arranged along the axial direction of the impeller, guide vanes in a first group of impeller assemblies are far away from a second group of impeller assemblies and are fixed with the left shell (111), guide vanes in a second group of impeller assemblies are fixed with the right shell (113), and the rotor assembly is arranged at the rim of the impeller with the small hub ratio.
3. A magnetically driven water jet propulsion pump with a low hub ratio impeller according to claim 2, characterized in that the spacer sleeve (13) is located inside the middle housing (112), the spacer sleeve (13) is sealingly connected to the left housing (111) at one end and to the right housing (113) at the other end and forms a pump chamber, the stator assembly (12) is mounted outside the spacer sleeve (13), and the rotor assembly (14) is mounted inside the spacer sleeve (13);
a water inlet (a) is formed in the left shell (111), a water outlet (b) is formed in the right shell (113), and the water inlet (a) and the water outlet (b) are coaxially arranged with the impeller shaft (151);
the guide vanes (152) in the first group of impeller assemblies are welded with the impeller shaft (151) in the first group of impeller assemblies and the left shell (111) into a whole; the guide vanes (152) in the second group of impeller assemblies are welded with the impeller shaft (11) in the second group of impeller assemblies and the right shell (113) into a whole;
the inner wall of the left shell (111) is provided with a step for inserting one end of the isolation sleeve (13), and the inner wall of the right shell (113) is provided with a step for inserting the other end of the isolation sleeve (13).
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|---|---|---|---|---|
| US6379113B1 (en) * | 1999-11-16 | 2002-04-30 | Chang Sun Kim | Propeller apparatus |
| US6991426B2 (en) * | 2001-01-11 | 2006-01-31 | Paolo Pietricola | Variable pitch fan |
| CN101888948A (en) * | 2007-12-28 | 2010-11-17 | 川崎重工业株式会社 | Thrust generator |
| CN107226189A (en) * | 2017-05-24 | 2017-10-03 | 武汉理工大学 | A kind of electromagnetism peculiar to vessel is to turning to have hub wheel rim hydraulic propeller |
| CN206943021U (en) * | 2017-04-28 | 2018-01-30 | 合肥工业大学 | A kind of Magnetic driving formula water jet propulsion pump |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6379113B1 (en) * | 1999-11-16 | 2002-04-30 | Chang Sun Kim | Propeller apparatus |
| US6991426B2 (en) * | 2001-01-11 | 2006-01-31 | Paolo Pietricola | Variable pitch fan |
| CN101888948A (en) * | 2007-12-28 | 2010-11-17 | 川崎重工业株式会社 | Thrust generator |
| CN206943021U (en) * | 2017-04-28 | 2018-01-30 | 合肥工业大学 | A kind of Magnetic driving formula water jet propulsion pump |
| CN107226189A (en) * | 2017-05-24 | 2017-10-03 | 武汉理工大学 | A kind of electromagnetism peculiar to vessel is to turning to have hub wheel rim hydraulic propeller |
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