CN108304645A - A kind of cavity noise generates and the integrated Mathematical Modeling Methods of propagation law - Google Patents
A kind of cavity noise generates and the integrated Mathematical Modeling Methods of propagation law Download PDFInfo
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Abstract
The invention discloses a kind of generations of cavity noise and the integrated Mathematical Modeling Methods of propagation law, specifically include following steps：Step S1：Establish the crucial effect parameter of cavity noise problem and the characterization parameter system of cavity noise problem；Step S2：Establish simultaneously abbreviation cavity compressible flows governing equation；Step S3：Establish the integrated mathematical modeling equation that cavity noise is generated and propagated；Step S4：Cavity aeroacoustics boundary condition is established, obtains the governing equation of cavity aeroacoustics wall condition and cavity aeroacoustics far field condition.The beneficial effects of the invention are as follows：It establishes cavity noise and generates mathematical modeling equation integrated with propagation law, can ensure the correctness of established equation from the root cause；Be conducive to the essence and key parameter of catching cavity noise to generate and propagate coupled problem, there is positive directive function for the experiment and numerically modeling of cavity noise research；Improve the cavity Efficiency of noise problem；It is generated for comprehensive analytical cavity noise and mechanism of transmission has established theoretical foundation.
Description
Technical field
The present invention relates to aerodynamics, aeroacoustics interleaving techniques fields, are a kind of cavity noise generations specifically
With the integrated Mathematical Modeling Methods of propagation law.
Background technology
The topology layout of cavity type generally existing in engineer application, for example, in bury weapon-bay, undercarriage cabin, height
Fast railcar join domain etc.；Under high speed inlet flow conditions, stream Induced Oscillation phenomenon easily occurs in cavity, leads to intracavitary noise ring
Border is severe, and one side cavity noise easily causes the vibration of cavity siding recurring structure, accelerates fatigue and the destruction of cavity siding, very
To cause cavity siding recurring structure resonate and cause safety accident；Another aspect cavity noise can also be to space after generation
It propagates, the noise intensity of cavity peripheral region is caused to increase, not only interfere the everyday environments around airport or railway, can also
It influences aircraft and reaches trial voyage or flight standard, cause serious economic loss.
Currently, research institution is outer more for the research of Cavity Flow characteristic both at home and abroad, for cavity noise generation with
The Study on Integration of propagation law is less；Tradition research method mainly with numerical computations and experiment based on, research process usually from
Cavity Flow characteristic is set out, and then on the Research foundation of Cavity Flow characteristic, is based on Lighthill aeroacoustics principles, into
The noise transmission rule of one step research cavity far-field region, hollow cavity far-field region refer in space far from cavity and by
Cavity nonstationary flow dynamic characteristic influences smaller area of space；Traditional cavity aeroacoustics equation is needed in known Cavity Flow spy
Cavity noise is described in the propagation law of far-field region on the basis of property, there are many deficiencies for this research method：
First, tradition research method does not use cavity noise generation to conduct a research with the integrated thinking of propagation law, it is right
In the noise of cavity near-field region generate the interaction relationship between rule and the noise transmission rule of cavity far-field region without
Method illustrates, and hollow cavity near-field region refers to being affected in space near cavity and by cavity nonstationary flow dynamic characteristic
Area of space；
Second is that propagation law of the tradition research method mainly for cavity noise in far-field region establishes equation, research process
Lack cavity noise generation and the integrated Mathematical Modeling Methods of propagation law, does not account for cavity noise and determine in near-field region
The modeling of justice and research regulation；
Third, tradition research method has artificially divided cavity near-field region and cavity far-field region, but cavity near-field region
Not fully aware of with the boundary of cavity far-field region, this dividing mode is unfavorable for the generation to cavity noise and propagation law
Carry out further Analysis on Mechanism.
Invention content
The purpose of the present invention is to provide a kind of cavity noises to generate and the integrated Mathematical Modeling Methods of propagation law, solution
Certainly the prior art generates cavity noise the deficiency with propagation law integrated analysis ability.
The present invention is achieved through the following technical solutions：A kind of cavity noise generates and the integrated mathematical modeling of propagation law
Method specifically includes following steps：
Step S1：Establish the crucial effect parameter of cavity noise problem and the characterization parameter system of cavity noise problem；
Step S2：Establish simultaneously abbreviation cavity compressible flows governing equation；
Step S3：Establish the integrated mathematical modeling equation that cavity noise is generated and propagated；
Step S4：Cavity aeroacoustics boundary condition is established, obtains cavity aeroacoustics wall condition and the pneumatic sound of cavity
Learn the governing equation of far field condition.
Further, in order to preferably realize that the present invention, the step S1 specifically refer to：The base flowed by analytical cavity
This rule establishes the crucial effect parameter system of cavity noise problem；According to this characteristic of cavity aeroacoustics, cavity noise is established
The characterization parameter system of problem；
The crucial effect parameter system specifically includes cavity geometric parameter and inlet flow conditions parameter；
The cavity geometric parameter includes cavity length L, cavity depth D and cavity width W；
The inlet flow conditions parameter includes incoming pressure medium ps, incoming Media density ρs, incoming medium temperature Ts, incoming
Dielectric viscosity μ, come flow medium specific heat ratio γ, incoming medium coefficient of heat conduction ks, carry out the specific heat at constant volume C of flow mediumν, carry out flow medium
Specific heat at constant pressure Cp, speed of incoming flow Us, speed of incoming flow direction three azimuth angle alphasl(l=1,2,3), speed edges layer thickness δ,
Displacement boundary layer thickness δ*And momentum boundary layer thickness θ；
The characterization parameter system specifically includes spatial position coordinate xk, time variable t, cavity flow field velocity component uk, it is empty
Sound pressure level p ', cavity noise caused by chamber flow field temperature T, cavity flow field density ρ, cavity fluid field pressure p, cavity noise cause close
Spend changing value ρ '；
Wherein：Subscript k (k=1,2,3) is indicated：Component of the physical quantity in three direction in spaces.
Further, in order to preferably realize that the present invention, the step S2 specifically include following steps：
Step S21：Based on aerodynamics basic principle, Cavity Flow governing equation under high speed inlet flow conditions is established,
Middle equation (1) is continuity equation, and equation (2) is the equation of momentum；
Wherein, in formula：Subscript k is indicated：Component of the physical quantity in three directions in space；
Subscript i, subscript j and subscript r are mute mark；
Step S22：Equation abbreviation is carried out for the basic characteristics of Cavity Flow governing equation, specifically includes following steps：
Step S221：Time derivation is carried out for equation (1), obtains equation (3)：
Step S222：Space derivation is carried out for equation (2), obtains equation (4)：
Step S223：Equation (3) is substituted into equation (4), and abbreviation is carried out to every in equation (1) and equation (2), must be changed
Equation (5) after letter：
Step S224：Items in equation (5) are merged, equation (6) is obtained：
Further, in order to preferably realize that the present invention, the step S3 specifically include following steps：
Step S31：According to aeroacoustics priori, cavity noise induced density pulsation equation (7) is established：
ρ '=ρ-ρs, (7)
Step S32：According to cavity noise fundamental characteristics, cavity flow field velocity of sound expression formula is established；It specifically refers to：It is opened with cavity
The shear layer in mouth region domain is boundary, and the space of shear layer both sides is divided into cavity inside region and cavity perimeter, enables cm(m
=1,2) it is the velocity of sound in cavity flow field, the flow field includes flow field and Flow Field outside；
Subscript m=1 indicates：The physical quantity corresponds to cavity inside flow field regions, and the velocity of sound of corresponding cavity flow field is side
Journey (8)：
Wherein, in formula：MsFor incoming fluid Mach number；
R is that cavity inside temperature restores the factor, it is generally the case that cavity inside temperature restores the factor close to 1；
Subscript m=2 indicate：The physical quantity corresponds to cavity External airflow field region, and the velocity of sound of corresponding cavity Flow Field outside is side
Journey (9)：
Step S33：By equation (7), cmEquation (6) is substituted into, and abbreviation is carried out to every in equation, equation (7) is based on, builds
Vertical cavity aeroacoustics governing equation：
In equation (10)The Evolution fluctuated for space density caused by cavity noise；Equation (10)
InCause the Crack cause that space density fluctuates for cavity noise.
Further, in order to preferably realize that the present invention, the step S4 specifically refer to：It is special according to cavity aeroacoustics
Property, establish cavity aeroacoustics boundary condition；The cavity aeroacoustics boundary condition includes cavity aeroacoustics wall condition
With cavity aeroacoustics far field condition；
According to aerodynamics and aeroacoustics priori, it is assumed that cavity wall surface meets adiabatic condition, the cavity
The governing equation of aeroacoustics wall condition is：
Wherein, in formula：DwIndicate that the cavity that cavity UNSTEADY FLOW is affected consolidates wall surface region；
According to aerodynamics and aeroacoustics priori, it is assumed that cavity far-field region meets hydrodynamics thermal insulation item
The governing equation of part, the cavity aeroacoustics far field condition is：
Wherein, in formula：D∞Indicate that cavity UNSTEADY FLOW influences the area of space of smaller separate cavity.
Compared with prior art, the present invention haing the following advantages and advantageous effect：
(1) present invention establishes cavity noise generation and propagation law from aerodynamics, aeroacoustics basic principle
Integrated mathematical modeling equation, can ensure the correctness of established equation from the root cause；
(2) cavity noise that the present invention establishes generates mathematical modeling equation integrated with propagation law and boundary condition,
The essence and key parameter for being conducive to catch cavity noise to generate and propagate coupled problem, for cavity noise research experiment with
Numerically modeling has positive directive function；
(3) hollow cavity noise of the present invention is generated can improve cavity noise with the integrated Mathematical Modeling Methods of propagation law
The Efficiency of problem；
(4) cavity noise that the present invention establishes generates mathematical modeling equation integrated with propagation law and boundary condition,
Include the mathematical modeling of cavity far-field region noise transmission mechanism, improves the simulation energy of cavity near-field region noise generation mechanism
Power generates for comprehensive analytical cavity noise and mechanism of transmission has established theoretical foundation.
Specific implementation mode
The present invention is described in further detail with reference to embodiment, embodiments of the present invention are not limited thereto.
Embodiment 1：
The present invention is achieved through the following technical solutions, and a kind of cavity noise generates and the integrated mathematical modeling of propagation law
Method, it is characterised in that：Specifically include following steps：
Step S1：Establish the crucial effect parameter of cavity noise problem and the characterization parameter system of cavity noise problem；
Step S2：Establish simultaneously abbreviation cavity compressible flows governing equation；
Step S3：Establish the integrated mathematical modeling equation that cavity noise is generated and propagated；Establish cavity noise generate with
The integrated mathematical modeling equation of propagation law, can ensure the correctness of established equation from the root cause；
Step S4：Cavity aeroacoustics boundary condition is established, obtains cavity aeroacoustics wall condition and the pneumatic sound of cavity
Learn the governing equation of far field condition.
The other parts of the present embodiment are same as the previously described embodiments, and so it will not be repeated.
Embodiment 2：
The present embodiment advanced optimizes on the basis of the above embodiments, further, in order to preferably realize this hair
Bright, the step S1 is specifically referred to：Basic law is flowed by analytical cavity, establishes the crucial effect parameter of cavity noise problem
System；According to this characteristic of cavity aeroacoustics, the characterization parameter system of cavity noise problem is established；
The crucial effect parameter system specifically includes cavity geometric parameter and inlet flow conditions parameter；
The cavity geometric parameter includes cavity length L, cavity depth D and cavity width W；
The inlet flow conditions parameter includes incoming pressure medium ps, incoming Media density ρs, incoming medium temperature Ts, incoming
Dielectric viscosity μ, come flow medium specific heat ratio γ, incoming medium coefficient of heat conduction ks, carry out the specific heat at constant volume C of flow mediumν, carry out flow medium
Specific heat at constant pressure Cp, speed of incoming flow Us, speed of incoming flow direction three azimuth angle alphasl(l=1,2,3), speed edges layer thickness δ,
Displacement boundary layer thickness δ*And momentum boundary layer thickness θ；
The characterization parameter system specifically includes spatial position coordinate xk, time variable t, cavity flow field velocity component uk, it is empty
Sound pressure level p ', cavity noise caused by chamber flow field temperature T, cavity flow field density ρ, cavity fluid field pressure p, cavity noise cause close
Spend changing value ρ '；
Wherein：Subscript k (k=1,2,3) is indicated：Component of the physical quantity in three direction in spaces.
Further, in order to preferably realize that the present invention, the step S2 specifically include following steps：
Step S21：Based on aerodynamics basic principle, Cavity Flow governing equation under high speed inlet flow conditions, institute are established
It includes continuity equation and the equation of momentum to state Cavity Flow governing equation under high speed inlet flow conditions；Wherein equation (1) is continuity equation,
Equation (2) is the equation of momentum；
Wherein, in formula：Subscript k is indicated：Component of the physical quantity in three directions in space；
Subscript i, subscript j and subscript r are mute mark；
Step S22：Equation abbreviation is carried out for the basic characteristics of Cavity Flow governing equation, specifically includes following steps：
Step S221：Time derivation is carried out for equation (1), obtains equation (3), equation (3) is：
Step S222：Space derivation is carried out for equation (2), obtains equation (4), equation (4) is：
Step S223：Equation (3) is substituted into equation (4), and abbreviation is carried out to every in equation (1) and equation (2), must be changed
Equation (5) after letter：
Step S224：Items in equation (5) are merged, equation (6) is obtained：
Further, in order to preferably realize that the present invention, the step S3 specifically include following steps：
Step S31：According to aeroacoustics priori, cavity noise induced density pulsation equation (7) is established：
ρ '=ρ-ρs, (7)
Step S32：According to cavity noise fundamental characteristics, cavity flow field velocity of sound expression formula is established；It specifically refers to：It is opened with cavity
The shear layer in mouth region domain is boundary, and the space of shear layer both sides is divided into cavity inside region and cavity perimeter, enables cm(m
=1,2) it is the velocity of sound in cavity flow field, the flow field includes flow field and Flow Field outside；
Subscript m=1 indicates：The physical quantity corresponds to cavity inside flow field regions, and the velocity of sound of corresponding cavity flow field is side
Journey (8)：
Wherein, in formula：MsFor incoming fluid Mach number；
R is that cavity inside temperature restores the factor, it is generally the case that cavity inside temperature restores the factor close to 1；
Subscript m=2 indicate：The physical quantity corresponds to cavity External airflow field region, and the velocity of sound of corresponding cavity Flow Field outside is side
Journey (9)：
Step S33：By equation (7), CmEquation (6) is substituted into, and abbreviation is carried out to every in equation, equation (7) is based on, builds
Vertical cavity aeroacoustics governing equation：
Further, in order to preferably realize that the present invention, the step S4 specifically refer to：It is special according to cavity aeroacoustics
Property, establish cavity aeroacoustics boundary condition；The cavity aeroacoustics boundary condition includes cavity aeroacoustics wall condition
With cavity aeroacoustics far field condition；
According to aerodynamics and aeroacoustics priori, it is assumed that cavity wall surface meets adiabatic condition, the cavity
The governing equation of aeroacoustics wall condition is：
Wherein, in formula：DwIndicate that the cavity that cavity UNSTEADY FLOW is affected consolidates wall surface region；
According to aerodynamics and aeroacoustics priori, it is assumed that cavity far-field region meets hydrodynamics thermal insulation item
The governing equation of part, the cavity aeroacoustics far field condition is：
Wherein, in formula：D∞Indicate that cavity UNSTEADY FLOW influences the area of space of smaller separate cavity.
The other parts of the present embodiment are same as the previously described embodiments, and so it will not be repeated.
Embodiment 3：
The present embodiment is highly preferred embodiment of the present invention：A kind of generation of cavity noise is built with the integrated mathematics of propagation law
Mould method, specifically includes following steps：
Step S1：Establish the crucial effect parameter of cavity noise problem and the characterization parameter system of cavity noise problem；Institute
Step S1 is stated to specifically refer to：The basic law flowed by analytical cavity, establishes the crucial effect system of parameters of cavity noise problem
System；According to this characteristic of cavity aeroacoustics, the characterization parameter system of cavity noise problem is established；
The crucial effect parameter system specifically includes cavity geometric parameter and inlet flow conditions parameter；
The cavity geometric parameter includes cavity length L, cavity depth D and cavity width W；
The inlet flow conditions parameter includes incoming pressure medium ps, incoming Media density ρs, incoming medium temperature Ts, incoming
Dielectric viscosity μ, come flow medium specific heat ratio γ, incoming medium coefficient of heat conduction ks, carry out the specific heat at constant volume C of flow mediumν, carry out flow medium
Specific heat at constant pressure Cp, speed of incoming flow Us, speed of incoming flow direction three azimuth angle alphasl(l=1,2,3), speed edges layer thickness δ,
Displacement boundary layer thickness δ*And momentum boundary layer thickness θ；
The characterization parameter system specifically includes spatial position coordinate xk, time variable t, cavity flow field velocity component uk, it is empty
Sound pressure level p ', cavity noise caused by chamber flow field temperature T, cavity flow field density ρ, cavity fluid field pressure p, cavity noise cause close
Spend changing value ρ '；
Wherein：Subscript k (k=1,2,3) is indicated：Component of the physical quantity in three direction in spaces.
Step S2：Establish simultaneously abbreviation cavity compressible flows governing equation；The step S2 specifically includes following steps：
Step S21：Based on aerodynamics basic principle, Cavity Flow governing equation under high speed inlet flow conditions, institute are established
It includes continuity equation and the equation of momentum to state Cavity Flow governing equation under high speed inlet flow conditions；Wherein equation (1) is continuity equation,
Equation (2) is the equation of momentum；
Wherein, in formula：Subscript k is indicated：Component of the physical quantity in three directions in space；
Subscript i, subscript j and subscript r are mute mark；
Step S22：Equation abbreviation is carried out for the basic characteristics of Cavity Flow governing equation, specifically includes following steps：
Step S221：Time derivation is carried out for equation (1), obtains equation (3)：
Step S222：Space derivation is carried out for equation (2), obtains equation (4)：
Step S223：Equation (3) is substituted into equation (4), and abbreviation is carried out to every in equation (1) and equation (2), must be changed
Equation (5) after letter：
Step S224：Items in equation (5) are merged, equation (6) is obtained：
Step S3：Establish the integrated mathematical modeling equation that cavity noise is generated and propagated；The step S3 is specifically included
Following steps：
Step S31：According to aeroacoustics priori, cavity noise induced density pulsation equation (7) is established：
ρ '=ρ-ρs, (7)
Step S32：According to cavity noise fundamental characteristics, cavity flow field velocity of sound expression formula is established；It specifically refers to：It is opened with cavity
The shear layer in mouth region domain is boundary, and the space of shear layer both sides is divided into cavity inside region and cavity perimeter, enables cm(m
=1,2) it is the velocity of sound in cavity flow field, the flow field includes flow field and Flow Field outside；Shear layer refers to having significantly speed in space
Spend a laminar flow body region of graded.
Subscript m=1 indicates：The physical quantity corresponds to cavity inside flow field regions, and the velocity of sound of corresponding cavity flow field is side
Journey (8)：
Wherein, in formula：MsFor incoming fluid Mach number；
R is that cavity inside temperature restores the factor；Under normal conditions, the value range of the cavity inside temperature recovery factor is：1
＞ r ＞ 0；
The optimal selected value that cavity inside temperature restores the factor usually requires to be obtained according to experiment or numerical simulation, using sky
Chamber internal temperature, which restores the factor, can more efficiently describe energy loss caused by the factors such as cavity inside viscous dissipation.
Subscript m=2 indicate：The physical quantity corresponds to cavity External airflow field region, and the velocity of sound of corresponding cavity Flow Field outside is side
Journey (9)：
Step S33：By equation (7), cmEquation (6) is substituted into, and abbreviation is carried out to every in equation；Based on equation (7), build
Vertical cavity aeroacoustics governing equation：
The item on equation (10) left side：The Evolution fluctuated for space density caused by cavity noise；
Item on the right of equation (10)：Cause space density wave for cavity noise
Dynamic Crack cause.
Item in cavity near-field region, equation (10) on the right of equal sign：By
To being affected for cavity nonstationary flow dynamic characteristic, equation (10) essentially describes the generation rule of cavity noise；
In cavity far-field region, the item in equation (10) on the right of equal sign：By
Influence to cavity nonstationary flow dynamic characteristic is smaller, and equation (10) essentially describes the propagation law of cavity noise；Therefore, equation
(10) it is capable of generation and the propagation law of Unify legislation space hollow cavity noise.
Step S4：Establish cavity aeroacoustics boundary condition.The step S4 is specifically referred to：
According to cavity aeroacoustics characteristic, cavity aeroacoustics boundary condition is established；The cavity aeroacoustics perimeter strip
Part includes cavity aeroacoustics wall condition and cavity aeroacoustics far field condition；
According to aerodynamics and aeroacoustics priori, it is assumed that cavity wall surface meets adiabatic condition, the cavity
The governing equation of aeroacoustics wall condition is：
Wherein, in formula：DwIndicate that the cavity that cavity UNSTEADY FLOW is affected consolidates wall surface region；
According to aerodynamics and aeroacoustics priori, it is assumed that cavity far-field region meets hydrodynamics thermal insulation item
The governing equation of part, the cavity aeroacoustics far field condition is：
Wherein, in formula：D∞Indicate that cavity UNSTEADY FLOW influences the area of space of smaller separate cavity.
It should be noted that by above-mentioned improvement, the present invention is built from aerodynamics, aeroacoustics basic principle
Vertical cavity noise generates mathematical modeling equation integrated with propagation law, can ensure the correct of established equation from the root cause
Property；
The cavity noise that the present invention establishes generates mathematical modeling equation integrated with propagation law and boundary condition, favorably
In the essence and key parameter of catching cavity noise to generate and propagate coupled problem, the experiment for cavity noise research and numerical value
Research has positive directive function；
Hollow cavity noise generation of the present invention can improve cavity noise with the integrated Mathematical Modeling Methods of propagation law and ask
The Efficiency of topic；
The cavity noise that the present invention establishes generates mathematical modeling equation integrated with propagation law and boundary condition, including
The mathematical modeling of cavity far-field region noise transmission mechanism improves the analog capability of cavity near-field region noise generation mechanism, is
Comprehensive analytical cavity noise generation has established theoretical foundation with mechanism of transmission.
The other parts of the present embodiment are same as the previously described embodiments, and so it will not be repeated.
Embodiment 4：
The present embodiment is another statement of the present invention, and the present invention proposes that a kind of cavity noise generates and propagation law
The technical solution of integrated Mathematical Modeling Methods, the method for the invention is as follows：
1. establishing the crucial effect parameter and characterization parameter system of cavity noise problem；
As shown in table 1- tables 3, analytical cavity noise generates the basic law with propagation, establishes the key of cavity noise problem
Affecting parameters and characterization parameter system.
The first step：Establish cavity noise key to the issue affecting parameters system.
According to the physical meaning of these parameters, by these parameters according to cavity geometric parameter as shown in Table 1 and such as 2 institute of table
The inlet flow conditions parameter shown is divided into two classes.
Second step：Establish the characterization parameter system of cavity noise problem.According to this characteristic of cavity aeroacoustics, cavity is established
The characterization parameter system of noise problem, as shown in table 3.
| Geometric parameter | Physical meaning |
| L | Cavity length |
| D | Cavity depth |
| W | Cavity width |
Table 1
Table 2
| Physical quantity | Physical meaning |
| xk | Spatial position coordinate |
| t | Time variable |
| uk | Cavity flow field velocity component |
| T | Cavity flow field temperature |
| ρ | Cavity flow field density |
| p | Cavity fluid field pressure |
| p′ | Sound pressure level caused by cavity noise |
| ρ′ | Cavity noise causes variable density value |
Table 3
2. establishing simultaneously abbreviation cavity compressible flows governing equation
The first step：Based on aerodynamics basic principle, Cavity Flow governing equation under high speed inlet flow conditions is established, wherein
Equation (1) is continuity equation, and equation (2) is the equation of momentum.
Wherein, subscript k is indicated：For physical quantity in the component in three directions in space, subscript i, subscript j and subscript r are mute mark.
Second step：Equation abbreviation is carried out for the basic characteristics of Cavity Flow governing equation；
1) it is directed to continuity equation (1) and carries out time derivation：
2) it is directed to the equation of momentum (2) and carries out space derivation：
3) equation (3) is substituted into equation (4), and abbreviation is carried out to every in continuity equation and the equation of momentum, abbreviation can be obtained
Equation afterwards is：
4) items in equation (5) are merged, can be obtained：
3. establishing the integrated mathematical modeling equation that cavity noise is generated and propagated
The first step：According to aeroacoustics priori, cavity noise induced density pulsation expression formula is established：
ρ '=ρ-ρs, (7)
Second step：According to cavity noise fundamental characteristics, cavity internal and external flow field velocity of sound expression formula is established.
Cavity internal and external flow field velocity of sound difference is larger, can be according to this feature, using the shear layer in cavities open region as boundary
Limit, is divided into two regions inside and outside two cavitys by the space of shear layer both sides, enables cm(m=1,2) it is the sound of cavity internal and external flow field
Speed；
M=1 is indicated：The physical quantity corresponds to cavity inside flow field regions：
Wherein, MsFor incoming fluid Mach number；R is that cavity inside temperature restores the factor, it is generally the case that cavity inside temperature
Degree restores the factor close to 1；
M=2 is indicated：The physical quantity corresponds to cavity inside flow field regions：
Third walks：Equation (7), equation (8) and equation (9) are substituted into equation (6), and abbreviation is carried out to every in equation,
Based on cavity noise induced density pulsation expression formula, cavity aeroacoustics governing equation is established：
Item in cavity near-field region, equation (10) on the right of equal sign：By
To being affected for cavity nonstationary flow dynamic characteristic, equation (10) essentially describes the generation rule of cavity noise；
In cavity far-field region, the item in equation (10) on the right of equal sign：By
Influence to cavity nonstationary flow dynamic characteristic is smaller, and equation (10) essentially describes the propagation law of cavity noise；Therefore, equation
(10) it is capable of generation and the propagation law of Unify legislation space hollow cavity noise.
4. establishing cavity aeroacoustics boundary condition
According to cavity aeroacoustics characteristic, cavity aeroacoustics boundary condition includes cavity aeroacoustics wall condition and sky
Chamber aeroacoustics far field condition.
In cavity near-field region, cavity noise is affected by cavity nonstationary flow dynamic characteristic, according to aerodynamics
And aeroacoustics priori, it is assumed that cavity wall surface meets adiabatic condition, then the control of the cavity aeroacoustics wall condition
Equation processed can be expressed as：
Wherein, DwIndicate that the cavity that cavity UNSTEADY FLOW is affected consolidates wall surface region；
In cavity far-field region, cavity noise influenced by cavity nonstationary flow dynamic characteristic it is smaller, according to aerodynamics
And aeroacoustics priori, it is assumed that cavity far-field region meets hydrodynamics adiabatic condition, then the cavity aeroacoustics
The governing equation of far field condition can be expressed as：
Wherein, D∞Indicate that cavity UNSTEADY FLOW influences the area of space of smaller separate cavity.
The other parts of the present embodiment are same as the previously described embodiments, and so it will not be repeated.
The above is only presently preferred embodiments of the present invention, not does limitation in any form to the present invention, it is every according to
According to the technical spirit of the present invention to any simple modification, equivalent variations made by above example, the protection of the present invention is each fallen within
Within the scope of.
Claims (5)
1. a kind of cavity noise generates and the integrated Mathematical Modeling Methods of propagation law, it is characterised in that：It specifically includes following
Step：
Step S1：Establish the crucial effect parameter of cavity noise problem and the characterization parameter system of cavity noise problem；
Step S2：Establish simultaneously abbreviation cavity compressible flows governing equation；
Step S3：Establish the integrated mathematical modeling equation that cavity noise is generated and propagated；
Step S4：Cavity aeroacoustics boundary condition is established, show that cavity aeroacoustics wall condition and cavity aeroacoustics are remote
The governing equation of field condition.
2. a kind of cavity noise according to claim 1 generates and the integrated Mathematical Modeling Methods of propagation law, spy
Sign is：The step S1 is specifically referred to：The basic law flowed by analytical cavity, establishes the crucial shadow of cavity noise problem
Ring parameter system；According to this characteristic of cavity aeroacoustics, the characterization parameter system of cavity noise problem is established；
The crucial effect parameter system specifically includes cavity geometric parameter and inlet flow conditions parameter；
The cavity geometric parameter includes cavity length L, cavity depth D and cavity width W；
The inlet flow conditions parameter includes incoming pressure medium ps, incoming Media density ρs, incoming medium temperature Ts, carry out flow medium
Sticky μ, come flow medium specific heat ratio γ, incoming medium coefficient of heat conduction ks, carry out the specific heat at constant volume C of flow mediumν, carry out determining for flow medium
The hot C of pressure ratiop, speed of incoming flow Us, speed of incoming flow direction three azimuth angle alphasl(l=1,2,3), speed edges layer thickness δ, displacement
Boundary layer thickness δ*And momentum boundary layer thickness θ；
The characterization parameter system specifically includes spatial position coordinate xk, time variable t, cavity flow field velocity component uk, cavity stream
Sound pressure level p ', cavity noise caused by field temperature T, cavity flow field density ρ, cavity fluid field pressure p, cavity noise cause density to become
Change value ρ '；
Wherein：Subscript k (k=1,2,3) is indicated：Component of the physical quantity in three direction in spaces.
3. a kind of cavity noise according to claim 2 generates and the integrated Mathematical Modeling Methods of propagation law, spy
Sign is：The step S2 specifically includes following steps：
Step S21：Based on aerodynamics basic principle, Cavity Flow governing equation under high speed inlet flow conditions is established, wherein just
Journey (1) is continuity equation, and equation (2) is the equation of momentum；
Wherein, in formula：Subscript k is indicated：Component of the physical quantity in three directions in space；
Subscript i, subscript j and subscript r are mute mark；
Step S22：Equation abbreviation is carried out for the basic characteristics of Cavity Flow governing equation, specifically includes following steps：
Step S221：Time derivation is carried out for equation (1), obtains equation (3)：
Step S222：Space derivation is carried out for equation (2), obtains equation (4), equation (4) is：
Step S223：Equation (3) is substituted into equation (4), and abbreviation is carried out to every in equation (1) and equation (2), after obtaining abbreviation
Equation (5)：
Step S224：Items in equation (5) are merged, equation (6) is obtained：
4. a kind of cavity noise according to claim 3 generates and the integrated Mathematical Modeling Methods of propagation law, spy
Sign is：The step S3 specifically includes following steps：
Step S31：According to aeroacoustics priori, cavity noise induced density pulsation equation (7) is established：
ρ '=ρ-ρs, (7)
Step S32：According to cavity noise fundamental characteristics, cavity flow field velocity of sound expression formula is established；It specifically refers to：With cavities open area
The shear layer in domain is boundary, and the space of shear layer both sides is divided into cavity inside region and cavity perimeter, enables cm(m=1,
2) it is the velocity of sound in cavity flow field, the flow field includes flow field and Flow Field outside；
Subscript m=1 indicates：The physical quantity corresponds to cavity inside flow field regions, and the velocity of sound of corresponding cavity flow field is equation
(8)：
Wherein, in formula：MsFor incoming fluid Mach number；
R is that cavity inside temperature restores the factor, it is generally the case that 1 ＞ r ＞ 0；
Subscript m=2 indicate：The physical quantity corresponds to cavity External airflow field region, and the velocity of sound of corresponding cavity Flow Field outside is equation
(9)：
Step S33：By equation (7), cmEquation (6) is substituted into, and abbreviation is carried out to every in equation, equation (7) is based on, establishes empty
Chamber aeroacoustics governing equation：
。
5. a kind of cavity noise according to claim 4 generates and the integrated Mathematical Modeling Methods of propagation law, spy
Sign is：The step S4 is specifically referred to：According to cavity aeroacoustics characteristic, cavity aeroacoustics boundary condition is established；It is described
Cavity aeroacoustics boundary condition includes cavity aeroacoustics wall condition and cavity aeroacoustics far field condition；
According to aerodynamics and aeroacoustics priori, it is assumed that cavity wall surface meets adiabatic condition, and the cavity is pneumatic
The governing equation of acoustics wall condition is：
Wherein, in formula：DwIndicate that the cavity that cavity UNSTEADY FLOW is affected consolidates wall surface region；
According to aerodynamics and aeroacoustics priori, it is assumed that cavity far-field region meets hydrodynamics adiabatic condition,
The governing equation of the cavity aeroacoustics far field condition is：
Wherein, in formula：D∞Indicate that cavity UNSTEADY FLOW influences the area of space of smaller separate cavity.
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