CN106934134B - A method of the unsteady intensity of pump cavitation is centrifuged for characterizing - Google Patents
A method of the unsteady intensity of pump cavitation is centrifuged for characterizing Download PDFInfo
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Abstract
The present invention relates to the cavitation fields of hydraulic, and in particular to a method of for characterizing the unsteady intensity of cavitation.In order to solve the problem of that there are lag and error using the cavitation development intensity of energy descent method characterization centrifugal pump in the prior art, the invention discloses a kind of methods for characterizing the centrifugation unsteady intensity of pump cavitation.Method includes the following steps: step 1, determines the characteristic parameter in centrifugal pump swing circle；Step 2 establishes model and carries out numerical simulation, obtains the Characteristic pressures pulsation Δ P of centrifugal pump and seeks its standard deviation S；Step 3 is established the dimensionless formula of the centrifugation unsteady intensity of pump cavitation, is calculated the unsteady intensity of cavitation of centrifugal pump under the cavitation conditions, and dimensionless factor Ci is obtained.Obtain by means of the present invention dimensionless number Ci characterization centrifugation pump cavitation develop intensity will than in the prior art using energy descent method characterization centrifugation pump cavitation develop intensity more precisely more rapidly.
Description
Technical field
The present invention relates to the cavitation fields of hydraulic, and in particular to one kind is for characterizing the centrifugation unsteady intensity of pump cavitation
Method.
Background technique
In the operational process of hydraulic, show since the local pressure decline in machinery can cause fluid to generate cavitation
As, cavitation is the phenomenon that one kind includes phase transformation, unsteady, multidimensional turbulent flow and the Various Complexes flowing such as compressible.Due to cavitation
The performance decline that will cause hydraulic is generated, and the vacuole that cavitation generates will cause mechanical surface when crumbling and fall
It destroys.Therefore, how the generation of Accurate Prediction cavitation and the development degree of cavitation are of great significance.
Currently, the method for assessing hydraulic machinery cavitation intensity is mainly energy descent method in the prior art, such as
The lift of water pump is declined into degree, lift coefficient decline degree of hydrofoil etc. develops the standard of intensity as cavitation is measured.Wherein,
The dimensionless group of a possibility that cavitation number occurs as characterization cavitation and description cavitation condition, the inlet pressure with centrifugal pump
It is closely related.It is monitored in the prior art by the lift exported to centrifugal pump under different cavitation numbers, by centrifugal pump lift
Decline cavitation inception point of the corresponding cavitation number as centrifugal pump when 3%.
However, not taken into account since the lift of centrifugal pump is a static critical value for embodying centrifugal pump external characteristics
Influence to cavitation to performance of centrifugal pump in dynamic and continuous cumulative process.Therefore, in the simulation to centrifugal pump operating status
Test during find, there is differences and lag between the slippage of lift and the development degree of cavitation, i.e., cavitation
When occurring and developed in certain phase, the output lift of centrifugal pump is remained unchanged.Therefore, before centrifugal pump
During phase design and test, if using the slippage of detection centrifugal pump lift as characterization centrifugation pump cavitation development degree
Parameter can there is lag and the problem of error, can not then determine fast and accurately in this way centrifugal pump really occur cavitation when
Between and development cavitation early period actual conditions, to be difficult to improve and set to improving centrifugal pump cavitation performance and make better structure
Meter.
Summary of the invention
In order to solve to develop intensity using the cavitation of energy descent method characterization centrifugal pump in the prior art, there are lag and mistake
The problem of difference, the invention proposes a kind of methods for characterizing the centrifugation unsteady intensity of pump cavitation.This method includes following step
It is rapid:
Step 1 determines the characteristic parameter in centrifugal pump swing circle, including characteristic dimension L, characteristic density ρ, feature speed
Spend U, the saturated vapour pressure P of characteristic time t and fluid media (medium)v；
Step 2 establishes model and carries out numerical simulation, one swing circle of centrifugal pump is obtained under determining cavitation conditions
Interior Characteristic pressures pulsation Δ P simultaneously seeks its standard deviation S, and wherein Characteristic pressures pulsation Δ P is equal to Characteristic pressures and fluid media (medium)
Saturated vapour pressure between difference:
Firstly, establishing model, N equal part is carried out to the unsteady computation time step number in one swing circle of centrifugal pump, and
And the time step of each equal part is Δ t；
Then, numerical simulation is carried out, t is extractednThe Characteristic pressures P at momentnWith void volume score αvn, obtain tnMoment
Characteristic pressures pulsation Δ Pn；Wherein tn=t0+ n Δ t, Δ Pn=Pn-Pv, t0For the initial time of unsteady cavitating flows, n is
Integer and 1≤n≤N；
Then, low pressure function Characteristics time formula is established, t is calculatednThe low pressure function Characteristics time t at momentln, and to tnWhen
The low pressure function Characteristics time t at quarter1nNondimensionalization is carried out, corresponding nondimensionalization coefficient k is obtainedn；Its mesolow function Characteristics
Time formulaDimensionless factor kn=tln/t；
Finally, with low pressure function Characteristics time tlnNondimensionalization coefficient knAs weight, to one revolution of centrifugal pump
Characteristic pressures pulsation Δ P in phasenIts standard deviation S is obtained after being weighted processing；Wherein standard deviation
Step 3 establishes the dimensionless formula of the centrifugation unsteady intensity of pump cavitation, to the sky of centrifugal pump under the cavitation conditions
Change unsteady intensity and calculate simultaneously nondimensionalization processing, obtains dimensionless factor Ci, wherein
Preferably, in said step 1, the characteristic dimension L chooses the radius size of centrifugal pump impeller, the feature
Density p chooses the density of fluid media (medium) in centrifugal pump, and the characteristic velocity U chooses the peripheral speed in centrifugal pump impeller exit,
The characteristic time t chooses the time that centrifugal pump impeller rotates a circle.
Preferably, in the step 2, centrifugal pump is carried out using SST k- ω turbulence model and Kubota cavitation model
The numerical simulation of interior full three-dimensional non-steady vacuole flowing.
Preferably, in the step 2, second swing circle for choosing centrifugal pump is non-as characterization centrifugation pump cavitation
The swing circle of permanent intensity.
Preferably, in the step 2, using centrifugal pump impeller 3 ° as one time step of every rotation, by centrifugal pump one
Unsteady computation time step number in a swing circle carries out 120 equal parts.
Preferably, in the step 2, tnThe Characteristic pressures P at momentnWith void volume score αvnIt is respectively as follows:WithWherein M is control unit sum, P in centrifugal pump impellermFor corresponding control
Absolute pressure value in unit, αvmFor the vapour phase volume fraction in corresponding control unit, VmFor the volume of corresponding control unit, V
For the volume for crossing flow medium in centrifugal pump impeller.
It is further preferred that adjusting the cavitation conditions in the step 2, the Ci value under different cavitation conditions is obtained, and intend
Close out the graph of relation under different cavitation conditions between cavitation number σ and dimensionless factor Ci.
Develop compared with intensity with energy descent method characterization centrifugation pump cavitation is used in the prior art, using side of the invention
The method characterization centrifugation unsteady intensity of pump cavitation has the advantages that
The present invention by establish model and formula introduce embody the dimensionless number Ci of the unsteady intensity of centrifugal pump characterize from
Cavitation development degree of the heart pump within the flowing special card period.By introducing inside centrifugal pump during establishing model and formula
The characteristic parameter of cavitating flow and flow field itself flow characteristics parameter, make the dimensionless number Ci finally obtained and fluid field pressure arteries and veins
Dynamic variation is consistent, and directly embodies the unsteady characteristic inside centrifugal pump.Due to the nascent and hair in centrifugation pump cavitation
The pace of change of unsteady characteristic and change intensity be all faster more than the variation of centrifugal pump external characteristics during exhibition, inside centrifugal pump
Precisely, therefore developing intensity using dimensionless number Ci characterization centrifugation pump cavitation will be characterized using energy descent method than in the prior art
Be centrifuged pump cavitation develop intensity more precisely more rapidly.In this way during the design early period of centrifugal pump and test, by establishing mould
Type and numerical simulation obtain dimensionless factor Ci, can judge the time of origin and hair of centrifugal pump interior cavitation fast and accurately
Exhibition situation improves the cavitation performance in centrifugal pump practical application to more accurately optimize to centrifugal pump structure.
Detailed description of the invention
Fig. 1 is the present invention for characterizing the flow diagram of the centrifugation unsteady intensity method of pump cavitation；
Fig. 2 is to be obtained under different cavitation conditions using the present invention for characterizing the unsteady intensity method of centrifugation pump cavitation, nothing
Graph of relation between dimension coefficient Ci and cavitation number σ；
Fig. 3 is obtained under different cavitation conditions using energy descent method in the prior art, and centrifugal pump exports lift H2 and sky
Change the graph of relation between number σ；
Fig. 4 is cavitation form schematic diagram in the centrifugal pump intercepted under different cavitation conditions in numerical simulation.
Specific embodiment
It describes in detail with reference to the accompanying drawing to technical solution of the present invention, the partial function symbol being related in the present invention
Meaning represented by number is as shown in the table.
As shown in connection with fig. 1, the characteristic parameter in centrifugal pump swing circle is determined；Model is established in centrifugal pump swing circle
Unsteady computation time step number divided；Carry out Characteristic pressures P, the vacuole in numerical simulation acquisition centrifugal pump swing circle
Volume fraction αvWith Characteristic pressures pulsation Δ P；It establishes low pressure function Characteristics time formula and seeks low pressure function Characteristics time tl, and
To low pressure signature time tlCarry out nondimensionalization processing；Again with low pressure function Characteristics time tlNondimensionalization COEFFICIENT KnAs power
Standard deviation is carried out to Characteristic pressures pulsation Δ P again to seek；Finally establish the dimensionless of the assessment centrifugation unsteady intensity of pump cavitation
Formula obtains the dimensionless factor Ci of the characterization centrifugation unsteady intensity of pump cavitation.
Specific step is as follows:
Step 1 determines the characteristic parameter in centrifugal pump swing circle, including characteristic dimension L, characteristic density ρ, feature speed
Spend U, the saturated vapour pressure P of characteristic time t and fluid media (medium)v.Wherein, characteristic dimension L is chosen for the radius of centrifugal pump impeller
Size, characteristic density ρ are chosen for the density of fluid media (medium) in centrifugal pump, and characteristic velocity U is chosen for centrifugal pump impeller exit
Peripheral speed, characteristic time t choose the time that centrifugal pump impeller rotates a circle.
Step 2, establishes model and carries out numerical simulation, and centrifugal pump is obtained under determining cavitation conditions in specific revolution
Characteristic pressures pulsation Δ P in phase, and calculate the standard deviation S of Characteristic pressures pulsation Δ P.Wherein, Characteristic pressures pulsation Δ P etc.
In the saturated vapour pressure P of Characteristic pressures P and fluid media (medium)vBetween difference.Detailed process are as follows:
Firstly, establishing model, a swing circle of centrifugal pump is chosen as the acquisition centrifugation unsteady intensity of pump cavitation
Specific swing circle, and N equal part, the time of each equal part are carried out to the unsteady computation time step number in the specific swing circle
Step-length is Δ t.
Preferably, it in the present invention, is carried out complete three in centrifugal pump using SST k- ω turbulence model and Kubota cavitation model
The numerical simulation of unsteady cavitation flowing is tieed up, and flowing is controlled using 15.0 fully implicit solution coupling technique of commercialization code ANSYS CFX
Equation group processed is solved.To in centrifugal pump impeller runner carry out hexahedral mesh division, centrifugal pump spiral casing using adaptability compared with
Strong tetrahedral grid accurately to capture centrifugal pump interior flow field structure, and checks final determining net by grid independence
Unit number M is controlled in lattice control unit number, number of nodes and impeller.
Model boundary condition is set, and wherein entrance is arranged to stagnation pressure import, and outlet is arranged to mass flow outlet, system ginseng
It examines pressure and is set as 0atm, cavitation critical pressure takes under room temperature the saturated vapour pressure of (25 DEG C) fluid media (medium), solid-surface boundary
It is arranged to without sliding wall surface (No Slip Wall).Sound interface is set as freezing rotor (Frozen in permanent calculating
Rator), using the result of convergent permanent calculating as the initial fields of unsteady computation, sound interface is set in unsteady computation
It is set to transient state and freezes rotor (TransientFrozen Rator).To the unsteady computation in the specific swing circle of centrifugal pump
Time step number carries out N equal part, and the time step of each equal part is Δ t.In addition, in the process for solving Fluid Control Equation group
The convection current discrete type of middle governing equation uses second order high accurate scheme, and time term discrete scheme is after second order to Euler's difference lattice
Formula, library bright number (CFL) lower limit are set as 0.5, and the upper limit is set as 1 to accelerate the convergence of each time step number, using maximum residul difference value as
Convergent discrimination standard is solved, convergence precision is set as 10-4。
Preferably, in the present invention, first swing circle for giving up centrifugal pump chooses second swing circle as table
The specific swing circle of the sign centrifugation unsteady intensity of pump cavitation, stable flowing shape is entered with the fluid media (medium) guaranteed in centrifugal pump
State.In addition, using centrifugal pump impeller 3 ° as one time step of every rotation, by the unsteady meter in the specific swing circle of centrifugal pump
Evaluation time step number carries out 120 equal parts.The temporal resolution that numerical value calculating can be improved in this way, guarantees the accurate of numerical simulation
Degree.
Then, numerical simulation is carried out under determining cavitation conditions, that is, determines that centrifugal pump inlet pressure boundary condition is laggard
Row numerical simulation.In numerical simulation, t in the specific swing circle of centrifugal pump is obtainednThe Characteristic pressures P at momentnWith vacuole body
Fraction αvnAnd tnThe Characteristic pressures pulsation Δ P at momentn.Wherein, tn=t0+ n Δ t,ΔPn=Pn-Pv；t0For the initial time of unsteady cavitating flows,
N is integer and 1≤n≤N, M are that unit number, P are controlled in centrifugal pump impellermFor the absolute pressure value in corresponding control unit, αvm
For the vapour phase volume fraction in corresponding control unit, VmFor the volume of corresponding control unit, V is that flow medium is crossed in centrifugal pump impeller
Volume, i.e. impeller computational domain.
In the present invention, due to using second swing circle of centrifugal pump as specific swing circle, and by specific rotation
Period is divided into 120 parts.Therefore, t0For the completion moment of first swing circle of centrifugal pump, i.e., centrifugal pump rotate a circle when
Between t；N is integer and 1≤n≤120；Pm、αvmAnd VmIt is to be obtained by numerical simulation calculation；V is determined by the structural parameters of centrifugal pump
Fixed.In this way by numerical simulation calculation, the Characteristic pressures P under 120 different moments may finally be obtainednWith void volume point
Number αvnAnd corresponding Characteristic pressures pulsation Δ Pn。
Then, low pressure function Characteristics time formula is established, t is calculatednWhen the low pressure function Characteristics time t that inscribesln, and to tn
When the low pressure function Characteristics time t that inscribes1nNondimensionalization is carried out, to obtain tnWhen inscribe low pressure function Characteristics time t1nNothing
Dimension coefficient kn.Wherein, tnWhen the low pressure function Characteristics time formula inscribed are as follows:
Low pressure function Characteristics time t1nNo quantization equation are as follows: kn=tln/t.In this way, t can be obtainednWhen inscribing low pressure function Characteristics
Between t1nNondimensionalization coefficient kn。
Finally, with low pressure function Characteristics time t1nNondimensionalization coefficient knAs weight, to the specific revolution of centrifugal pump
Characteristic pressures pulsation Δ P in phasenStandard deviation calculating is carried out after weighting processing, obtains Characteristic pressures pulsation Δ PnQuasi- difference S,
Wherein
Step 3 establishes the dimensionless formula of the centrifugation unsteady intensity of pump cavitation, calculates and characterizes centrifugation under the cavitation conditions
The dimensionless factor Ci of the unsteady intensity of pump cavitation.Wherein
It is further preferred that changing the inlet-pressure set in numerical simulation by adjusting the cavitation conditions in step 2
Force boundary condition obtains the dimensionless factor Ci that the unsteady intensity of pump cavitation is centrifuged under different cavitation conditions, and according to different skies
Corresponding relationship under the conditions of change between cavitation number σ and dimensionless factor Ci fits graph of relation between the two, thus right
The development of the centrifugation unsteady intensity of pump cavitation is assessed.
A centrifugal pump is chosen below as experimental subjects and characterization of the present invention is carried out using pure water as Experimental Flowing Object medium
It is centrifuged the calculating of the dimensionless factor Ci of the unsteady intensity of pump cavitation, and the cavitation aspect graph by obtaining in numerical simulation
It is compared with the energy descent method for characterizing centrifugal pump cavitation intensity in the prior art.
The structural parameters of centrifugal pump are as shown in the table:
Characteristic ginseng value in centrifugal pump swing circle is respectively as follows: characteristic dimension and takes impeller radius L=0.155m, feature speed
Degree takes the peripheral speed U=8.2m/s at impeller outlet, and the characteristic time takes impeller to rotate a circle time t=0.12s used, feature
Density takes pure water density p=1000kg/m3, the saturated vapor pressure P of fluid media (medium)v=3169Pa.At this point, by the specific of centrifugal pump
After swing circle carries out 120 parts of equal parts, the time step Δ t=t/120=0.001s of each equal part.In addition, in numerical simulation
In, to hexahedral mesh division is carried out in centrifugal pump impeller runner, centrifugal pump spiral casing uses the stronger tetrahedral grid of adaptability
Afterwards, it is checked by grid independence, final to determine that grid control unit number is 1017321, number of nodes 838520, wherein impeller
Interior control unit number M is 675917.
Cavitation number σ is adjusted in numerical simulation and sets different inlet pressure boundary conditions, obtains corresponding dimensionless
Coefficient Ci.Wherein, it when inlet pressure boundary condition corresponding with cavitation number σ=0.14 is set in numerical simulation, is corresponded to
Dimensionless factor Ci=-6.7；When inlet pressure boundary condition corresponding with cavitation number σ=0.09 is set in numerical simulation,
Obtain corresponding dimensionless factor Ci=-3.9；Inlet pressure corresponding with cavitation number σ=0.015 side is set in numerical simulation
When boundary's condition, corresponding dimensionless factor Ci=-1.67 is obtained.And according to cavitation number σ and dimensionless factor Ci, fit sky
Change the graph of relation between number σ and dimensionless factor Ci, as shown in Figure 2.
In addition, being controlled using commercial 15.0 fully implicit solution coupling technique of code ANSYS CFX flowing in numerical simulation
Equation group carries out permanent calculating, uses SST k- ω model in turbulence model and does not choose the item of cavitation (Cavitation) option
Under part, lift value H of the centrifugal pump when cavitation does not occur is calculated1.Then cavitation (Cavitation) option is chosen
And cavitation model uses Kubota cavitation model, by adjusting cavitation conditions, i.e. inlet pressure side in adjustment numerical simulation
Boundary's condition calculates lift value H of the centrifugal pump under different cavitation conditions2And lift slippage Δ H, wherein Δ H=H2-
H1.It fits under the centrifugal pump difference cavitation conditions, cavitation number σ and lift H2Between graph of relation, as shown in Figure 3.Together
When, in numerical simulation, the cavitation form schematic diagram under different cavitation conditions in centrifugal pump is intercepted, as shown in Figure 4.Its
In, each width cavitation form schematic diagram in Fig. 4 all simultaneously cavitation number σ, lift slippage Δ H under the corresponding cavitation conditions with
And dimensionless factor Ci.
Known to the variation corresponding relationship between cavitation number σ and dimensionless factor Ci as shown in Figure 2: when the cavitation of centrifugal pump
When i.e. cavitation number σ changes when condition changes, the dimensionless factor Ci of the characterization centrifugation unsteady intensity of pump cavitation is at once
Change along with the variation of cavitation number σ.And cavitation intensity is continuously increased therewith, i.e., and it is when cavitation number σ gradually becomes smaller, immeasurable
Guiding principle coefficient Ci then becomes larger and keeps increase tendency.Situation of change can be worth according to dimensionless factor Ci in this way, to centrifugation
The cavitation development trend and degree of pump are tentatively judged.Cavitation number σ and centrifugal pump as shown in Figure 3 exports lift value H2Between
Variation corresponding relationship known to: in occurrence and development early period of cavitation, especially cavitation number σ was reduced to for 0.03 stage by 0.14
Process, the output lift value H of centrifugal pump2Be kept approximately constant i.e. characterization centrifugal pump cavitation not yet occurs, this and centrifugation pump cavitation
The actual development of development has differences, and has serious hysteresis quality.In addition, as shown in connection with fig. 4, by observation centrifugal pump in different skies
Cavitation form schematic diagram under the conditions of change can intuitively be found, during cavitation number σ is gradually decreased as 0.03 by 0.14, due to
The increase of cavitation intensity and cause the void volume inside centrifugal pump impeller to become larger, wherein in Fig. 4 symbol 1 indicate region
For vacuole caused by cavitation.During this period, dimensionless factor Ci gradually increases to -2.27 by -6.70 and quickly reflects centrifugal pump
Cavitation develops the variation of intensity.But it is 0 that the lift drop-out value Δ H of centrifugal pump, which is but always showed,.When cavitation number σ reaches 0.02
When, just there is variation characterization centrifugal pump and enters the cavitation inception stage in lift drop-out value Δ H, and actually the cavitation of centrifugal pump has been at this time
Through entering developing stage.
By being characterized to using dimensionless factor Ci characterization cavitation development intensity and using the lift drop-out value Δ H of centrifugal pump
Cavitation develop intensity comparative analysis can be apparent discovery, dimensionless factor Ci can more rapidly, more accurately characterize from
The occurrence and development progress of heart pump cavitation.
Claims (6)
1. a kind of method for characterizing the centrifugation unsteady intensity of pump cavitation, which is characterized in that method includes the following steps:
Step 1, determines the characteristic parameter in centrifugal pump swing circle, including characteristic dimension L, characteristic density ρ, characteristic velocity U,
The saturated vapour pressure P of characteristic time t and fluid media (medium)v；
Step 2 establishes model and carries out numerical simulation, obtains in one swing circle of centrifugal pump under determining cavitation conditions
Characteristic pressures pulsation Δ P simultaneously seeks its standard deviation S, and wherein Characteristic pressures pulsation Δ P is equal to the full of Characteristic pressures and fluid media (medium)
Difference between vapour pressure:
Firstly, establishing model, N equal part is carried out to the unsteady computation time step number in one swing circle of centrifugal pump, and every
The time step of one equal part is Δ t；
Then, numerical simulation is carried out, t is extractednThe Characteristic pressures P at momentnWith void volume score αvn, obtain tnThe feature at moment
Pressure fluctuation Δ Pn；Wherein tn=t0+ n Δ t, Δ Pn=Pn-Pv, t0For the initial time of unsteady cavitating flows, n is integer
And 1≤n≤N；
Then, low pressure function Characteristics time formula is established, t is calculatednThe low pressure function Characteristics time t at momentln, and to tnMoment
Low pressure function Characteristics time t1nNondimensionalization is carried out, corresponding nondimensionalization coefficient k is obtainedn；Its mesolow function Characteristics time
FormulaDimensionless factor kn=tln/t；
Finally, with low pressure function Characteristics time tlnNondimensionalization coefficient knAs weight, in one swing circle of centrifugal pump
Characteristic pressures pulse Δ PnIts standard deviation S is obtained after being weighted processing；Wherein standard deviation
Step 3 establishes the dimensionless formula of the centrifugation unsteady intensity of pump cavitation, non-to the cavitation of centrifugal pump under the cavitation conditions
Permanent intensity calculate and nondimensionalization processing, obtains dimensionless factor Ci；Wherein
In said step 1, the characteristic dimension L chooses the radius size of centrifugal pump impeller, the characteristic density ρ choose from
The density of fluid media (medium) in heart pump, the characteristic velocity U choose the peripheral speed in centrifugal pump impeller exit, the characteristic time
T chooses the time that centrifugal pump impeller rotates a circle.
2. the method according to claim 1 for characterizing the centrifugation unsteady intensity of pump cavitation, which is characterized in that the step
In rapid two, full three-dimensional non-steady vacuole flowing in centrifugal pump is carried out using SST k- ω turbulence model and Kubota cavitation model
Numerical simulation.
3. the method according to claim 1 for characterizing the centrifugation unsteady intensity of pump cavitation, which is characterized in that described
In step 2, swing circle of second swing circle of centrifugal pump as the assessment centrifugation unsteady intensity of pump cavitation is chosen.
4. the method according to claim 1 for characterizing the centrifugation unsteady intensity of pump cavitation, which is characterized in that described
It, will be unsteady in one swing circle of centrifugal pump using centrifugal pump impeller 3 ° as one time step of every rotation in step 2
It calculates time step number and carries out 120 equal parts.
5. the method according to claim 1 for characterizing the centrifugation unsteady intensity of pump cavitation, which is characterized in that described
In step 2, tnThe Characteristic pressures P at momentnWith void volume score αvnIt is respectively as follows:WithWherein M is control unit sum, P in centrifugal pump impellermFor the absolute pressure in corresponding control unit
Value, αvmFor the vapour phase volume fraction in corresponding control unit, VmFor the volume of corresponding control unit, V is mistake in centrifugal pump impeller
The volume of flow medium.
6. the method described in any one of -5 for characterizing the centrifugation unsteady intensity of pump cavitation according to claim 1, special
Sign is, adjusts the cavitation conditions in the step 2, obtains the Ci value under different cavitation conditions, and fits different cavitation items
Graph of relation under part between cavitation number σ and dimensionless factor Ci.
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| 《空化条件下离心泵泵腔内不稳定流动数值分析》;司乔瑞等;《农业机械学报》;20140531;第85-90页 |
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