CN112699470B - Arrangement method of cavity noise control device - Google Patents

Arrangement method of cavity noise control device Download PDF

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CN112699470B
CN112699470B CN202011602587.5A CN202011602587A CN112699470B CN 112699470 B CN112699470 B CN 112699470B CN 202011602587 A CN202011602587 A CN 202011602587A CN 112699470 B CN112699470 B CN 112699470B
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sound
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pneumatic noise
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CN112699470A (en
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高飞
胡陈映
顾金桃
王美燕
肖乾
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AVIC First Aircraft Institute
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    • G06F30/00—Computer-aided design [CAD]
    • G06F30/10—Geometric CAD
    • G06F30/15—Vehicle, aircraft or watercraft design
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/28—Design optimisation, verification or simulation using fluid dynamics, e.g. using Navier-Stokes equations or computational fluid dynamics [CFD]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/10—Noise analysis or noise optimisation
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    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation

Abstract

The invention belongs to the field of airplane noise control, and provides an arrangement method of a cavity noise control device, which comprises the steps of establishing a cavity pneumatic noise analysis model, and calculating the established cavity pneumatic noise analysis model by utilizing computational fluid mechanics software or computational pneumatic acoustics software according to the determined flow field analysis conditions to obtain the cavity pneumatic noise sound source characteristics; determining a pneumatic noise observation point in the cavity according to the size of a pneumatic noise sound source in the cavity; and judging whether the cavity pneumatic noise sound source characteristic of the pneumatic noise observation point in the cavity meets a set value or not according to the obtained pneumatic noise sound source characteristic of the pneumatic noise observation point, and inputting the position of the turbulence device if the cavity pneumatic noise sound source characteristic of the pneumatic noise observation point in the cavity does not meet the set value. The mounting position of the cavity front edge turbulence device can be optimized; an analysis step of the noise control device arrangement is also proposed.

Description

Arrangement method of cavity noise control device
Technical Field
The invention belongs to the field of airplane noise control, and relates to an arrangement method of a cavity noise control device.
Background
Cavity structures are common structures of aircraft, such as landing gear bays, slat/flap bays, equipment bays, and magazine bays. During the taking off and landing process and the flying process of the airplane, when the cabin door is opened, the cavity is exposed to airflow, the incoming flow shear layer in the front of the cavity interacts with the airflow in the cavity, and self-oscillation is possibly generated to generate strong noise. On one hand, strong noise can affect the environment around an airport, so that noise pollution is caused; on the other hand, strong cavity noise can lead to structural damage inside the cavity, equipment malfunction or malfunction, and in severe cases, flight safety can be compromised.
The current common cavity noise control device is to install a spoiler device, such as a swash plate device, a flat plate device, a sawtooth device, a cylindrical device, a perforated plate device, etc., at the front edge of the cavity. These devices have a cavity noise suppression effect, but the arrangement positions of the devices are closely related to the cavity internal noise.
The invention provides an arrangement method of cavity noise control devices, which can optimize the installation position of a cavity front edge turbulence device and evaluate the noise control effect in a cavity; an analysis step of the noise control device arrangement is also proposed.
Disclosure of Invention
The purpose of the invention is as follows: the arrangement method of the cavity noise control device is provided, and the installation position of the cavity front edge turbulence device can be optimized; an analysis step of the noise control device arrangement is also proposed. Analysis shows that the position of the turbulence device is optimized, and the noise in the cavity can be reduced by 8 dB.
The technical scheme is as follows: there is provided an arrangement method of a cavity noise control device, including the steps of:
step 1: determining the analysis condition of the cavity flow field;
step 2: establishing a cavity pneumatic noise analysis model, and calculating the established cavity pneumatic noise analysis model by utilizing computational fluid mechanics software or computational pneumatic acoustic software according to the determined flow field analysis conditions to obtain the cavity pneumatic noise sound source characteristics;
and step 3: determining a pneumatic noise observation point in the cavity according to the size of a pneumatic noise sound source in the cavity;
and 4, step 4: judging whether the cavity pneumatic noise sound source characteristics of the pneumatic noise observation points in the cavity meet set values or not according to the pneumatic noise sound source characteristics of the pneumatic noise observation points obtained in the step 2 and the step 3, and if not, executing the step 5 until the sound pressure level of the sound field in the cavity obtained by calculation meets the set values; if yes, executing step 6;
and 5: inputting the position of the turbulence device, and repeating the steps 2 to 4;
step 6: establishing a sound field analysis model; calculating the sound field characteristics inside the cavity by using the calculated characteristics of the cavity pneumatic noise sound source as excitation conditions and utilizing an acoustic finite element or acoustic boundary element calculation method for the established sound field analysis model; the cavity interior sound field characteristics include an interior sound field sound pressure level and a sound field frequency.
Further, the analysis conditions include gas density, gas temperature, sound velocity, gas flow velocity, flying height of the cavity, and cavity size.
Further, the cavity aerodynamic noise source characteristics include airflow density, pressure, velocity distribution inside the cavity, and pulsating pressure of the cavity interior surface.
Further, the sound pressure level of the sound field inside the cavity refers to the change of the distribution of the pressure inside the cavity along with time.
Further, the method for calculating the characteristics of the cavity aerodynamic noise sound source is to adopt a separation vortex model to calculate turbulence, wherein the air flow speed u of the turbulence is calculated i The calculation formula of (2) is as follows:
Figure BDA0002869707930000021
wherein
Figure BDA0002869707930000022
Is the vortex viscosity coefficient, ρ is the air flow density, u i Is the velocity of the gas stream, x j Is the coordinate, i, j ═ 1,2,3, σ v ,c b2 Is a constant value, S v Is a custom source item;
G v is a term for the generation of a turbulent viscosity,
Figure BDA0002869707930000023
wherein
Figure BDA0002869707930000024
κ,c b1 Is a constant, S is a tensor deformation scale,
Figure BDA0002869707930000025
Ω ij is the mean rate of rotation of the tensor,
Figure BDA0002869707930000026
the length of the first and second support members,
Figure BDA0002869707930000027
d distance of grid from wall, Δ max Is the maximum dimension of the grid, C des The empirical coefficient is 0.65;
Y v is a term for the reduction of the turbulent viscosity,
Figure BDA0002869707930000028
wherein
Figure BDA0002869707930000029
g＝r+c w2 (r 6 -r)，
Figure BDA00028697079300000210
c w1 ,c w2 ,c w3 Is a constant;
Figure BDA00028697079300000211
by using a separation vortex model, according to the calculated airflow speed u of the turbulent flow i The turbulent gas flow pressure, turbulent pressure and pulsating pressure of the inner surface of the cavity are derived.
Further, in step 5, the position of the spoiler
Figure BDA00028697079300000212
The calculation formula of (2) is as follows:
Figure BDA00028697079300000213
wherein p is i Is the pressure at the ith observation point inside the cavity; a. the 1 、A 2 Is a constant, determined analytically or experimentally;
Figure BDA0002869707930000031
is the position of the turbulence device away from the front edge of the cavity,
Figure BDA0002869707930000032
is the position of the observation point inside the cavity,
Figure BDA0002869707930000033
L 0 is a cavityThe characteristic dimension.
Further, in step 5, the characteristic dimension of the cavity includes a length L of the cavity, or a width W of the cavity, or a depth D of the cavity.
Further, in step 6, obtaining the sound pressure p inside the cavity by using an integral calculation formula of an acoustic finite element; wherein, the integral calculation formula of the acoustic finite element is as follows:
Figure BDA0002869707930000034
where p is the sound pressure inside the cavity,
Figure BDA0002869707930000035
is a function of the weight of the image,
Figure BDA0002869707930000036
q is the volume velocity per unit volume in the cavity. V is the cavity volume, Ω is the cavity surface, ρ 0 Is the airflow density, ω is the circular frequency, ω -2 pi f, f is the noise frequency,
Figure BDA0002869707930000037
is a vector of the velocity of the air flow,
Figure BDA0002869707930000038
is the cavity wall direction vector.
Further, in step 6, obtaining the sound pressure p inside the cavity by using an integral calculation formula of the acoustic boundary element; the calculation method of the acoustic boundary element comprises the following steps:
calculating the volume V of the cavity at any point not on the surface omega of the cavity
Figure BDA0002869707930000039
The sound pressure p is calculated by the formula:
Figure BDA00028697079300000310
and is
Figure BDA00028697079300000311
Wherein { C i And { D } i The elements of are respectively:
Figure BDA00028697079300000312
i＝1,2,3,…,n a ，n a is the number of all nodes of the divided grid of the cavity surface,
Figure BDA00028697079300000313
is a function of the green's function,
Figure BDA00028697079300000314
satisfy the requirement of
Figure BDA00028697079300000315
N i Is a matrix of shape functions, N i Are respectively as
Figure BDA00028697079300000316
Wherein
Figure BDA00028697079300000317
And
Figure BDA00028697079300000318
respectively the sound pressure and normal velocity of a point inside a certain grid unit divided by the surface of the cavity pi And a vi Is the sound pressure and normal velocity at the unit node,
Figure BDA00028697079300000319
is an inner point of the grid cell, n e Is the grid cell omega a The number of nodes.
The technical effects are as follows: the invention provides an arrangement method of a cavity noise control device, which can optimize the installation position of a cavity front edge turbulence device; an analysis step of the noise control device arrangement is also proposed. Analysis shows that the noise in the cavity can be reduced by 8dB by optimizing the position of the turbulence device. The arrangement method of the cavity noise control device is easy to realize; the used cavity noise control method is effective, and the cavity noise can be obviously reduced.
Drawings
FIG. 1 is a flow chart of a method of arranging a cavity noise control device;
fig. 2 is a schematic layout of a cavity noise control device.
Detailed Description
Fig. 1 is a flow chart of an arrangement method of a cavity noise control device, and in combination with fig. 1, an arrangement method of a cavity noise control device includes the following steps:
step 1: determining the analysis condition of the cavity flow field; the analysis conditions include gas density, gas temperature, sonic velocity, gas flow velocity, flight height of the cavity, cavity size.
And 2, step: and establishing a cavity pneumatic noise analysis model, and calculating the established cavity pneumatic noise analysis model by utilizing computational fluid mechanics software or computational pneumatic acoustics software according to the determined flow field analysis conditions to obtain the cavity pneumatic noise sound source characteristics. The cavity aerodynamic noise source characteristics include airflow density, pressure, velocity distribution inside the cavity, and pulsating pressure of the cavity interior surface.
The method for calculating the characteristics of the cavity aerodynamic noise sound source comprises the steps of calculating turbulence by adopting a separation vortex model, wherein the air flow speed u of the turbulence i The calculation formula of (2) is as follows:
Figure BDA0002869707930000041
wherein
Figure BDA0002869707930000042
Is the vortex viscosity coefficient, ρ is the air flow density, u i Is the velocity of the gas stream, x j Is the coordinate, i, j ═ 1,2,3, σ v ,c b2 Is a constant value, S v Is a custom source item;
G v is a term for the generation of a turbulent viscosity,
Figure BDA0002869707930000043
wherein
Figure BDA0002869707930000044
κ,c b1 Is a constant, S is a tensor deformation scale,
Figure BDA0002869707930000045
Ω ij is the mean rate of rotation of the tensor,
Figure BDA0002869707930000046
the length of the first and second support members,
Figure BDA0002869707930000047
d distance of grid from wall, Δ max Is the maximum dimension of the grid, C des The empirical coefficient is 0.65;
Y v is a term for the reduction of the turbulent viscosity,
Figure BDA0002869707930000048
wherein
Figure BDA0002869707930000049
g＝r+c w2 (r 6 -r)，
Figure BDA00028697079300000410
c w1 ,c w2 ,c w3 Is a constant;
Figure BDA00028697079300000411
using a separation vortex model, based on the calculated air velocity u of the turbulent flow i The turbulent gas flow pressure, turbulent pressure and pulsating pressure of the inner surface of the cavity are derived.
And step 3: and determining a pneumatic noise observation point in the cavity according to the pressure of the pneumatic noise source in the cavity.
And 4, step 4: judging whether the cavity pneumatic noise sound source characteristics of the pneumatic noise observation points in the cavity meet set values or not according to the pneumatic noise sound source characteristics of the pneumatic noise observation points obtained in the step 2 and the step 3, and if not, executing the step 5 until the sound pressure level of the sound field in the cavity obtained by calculation meets the set values; if yes, go to step 6.
And 5: FIG. 2 is a schematic diagram of an arrangement of a cavity noise control device, which is combined with the position of the input spoiler shown in FIG. 2
Figure BDA00028697079300000516
Obtaining the pressure p of the ith observation point in the cavity i Repeating the step 2 to the step 4; wherein the position of the flow-disturbing means
Figure BDA00028697079300000517
The calculation formula of (2) is as follows:
Figure BDA0002869707930000051
wherein p is i Is the pressure at the ith observation point inside the cavity; a. the 1 、A 2 Is a constant, determined analytically or experimentally;
Figure BDA0002869707930000052
is the position of the turbulence device away from the front edge of the cavity,
Figure BDA0002869707930000053
is the position of the observation point inside the cavity,
Figure BDA0002869707930000054
L 0 is the characteristic dimension of the cavity. The cavity characteristic dimension includes a cavity length L, or a cavity width W, or a cavity depth D.
And 6: establishing a sound field analysis model; calculating the sound field characteristics inside the cavity by using the calculated cavity pneumatic noise sound source characteristics as excitation conditions and using an acoustic finite element or acoustic boundary element calculation method for the established sound field analysis model; the cavity interior sound field characteristics include an interior sound field sound pressure level and a sound field frequency.
The integral calculation formula of the acoustic finite element is as follows:
Figure BDA0002869707930000055
where p is the sound pressure inside the cavity,
Figure BDA0002869707930000056
is a function of the weight of the image,
Figure BDA0002869707930000057
q is the volume velocity per unit volume in the cavity. V is the cavity volume, Ω is the cavity surface, ρ 0 Is the airflow density, ω is the circular frequency, ω -2 pi f, f is the noise frequency,
Figure BDA0002869707930000058
is a vector of the velocity of the air flow,
Figure BDA0002869707930000059
is the cavity wall direction vector.
Obtaining the sound pressure p in the cavity by utilizing an integral calculation formula of the acoustic boundary element; the method for calculating the acoustic boundary element comprises the following steps: calculating the volume V of the cavity at any point not on the surface omega of the cavity
Figure BDA00028697079300000510
The sound pressure p is calculated by the formula:
Figure BDA00028697079300000511
and is
Figure BDA00028697079300000512
Wherein { C i And { D } i The elements of (h) are:
Figure BDA00028697079300000513
i＝1,2,3,…,n a ，n a all node numbers of the division grid which is the surface of the cavity，
Figure BDA00028697079300000514
Is a function of the green's function,
Figure BDA00028697079300000515
satisfy the requirement of
Figure BDA0002869707930000061
N i Is a matrix of shape functions, N i Are respectively as
Figure BDA0002869707930000062
Wherein
Figure BDA0002869707930000063
And
Figure BDA0002869707930000064
respectively the sound pressure and normal velocity of a point inside a certain grid unit divided by the surface of the cavity pi And a vi Is the sound pressure and normal velocity at the unit node,
Figure BDA0002869707930000065
is an inner point of the grid cell, n e Is the grid cell omega a The number of nodes.
The invention relates to an arrangement method of a cavity noise control device. In the cavity flowing process, an incoming flow boundary layer is separated at the front end of the cavity, wherein the unstable shear layer collides with the rear wall of the cavity to generate disturbance waves, and then the disturbance waves are fed back to the front end of the cavity in an aerodynamic or acoustic mode to form a further coupling effect on the incoming flow boundary layer, so that self-excited oscillation is formed when specific conditions are met, and strong noise is generated. According to the cavity noise generation mechanism, the turbulent flow device is arranged at the proper position of the front edge of the cavity to force the airflow to deflect upwards and reduce the impact on the rear wall of the cavity. The arrangement method of the cavity noise control device can optimize the installation position of the cavity front edge turbulence device.

Claims (9)

1. A method of arranging cavity noise control devices, comprising the steps of:
step 1: determining the analysis condition of the cavity flow field;
step 2: establishing a cavity pneumatic noise analysis model, and calculating the established cavity pneumatic noise analysis model by utilizing computational fluid mechanics software or computational pneumatic acoustic software according to the determined flow field analysis conditions to obtain the cavity pneumatic noise sound source characteristics;
and step 3: determining a pneumatic noise observation point in the cavity according to the size of a pneumatic noise sound source in the cavity;
and 4, step 4: judging whether the cavity pneumatic noise sound source characteristics of the pneumatic noise observation points in the cavity meet set values or not according to the pneumatic noise sound source characteristics of the pneumatic noise observation points obtained in the step 2 and the step 3, and if not, executing the step 5 until the sound pressure level of the sound field in the cavity obtained by calculation meets the set values; if yes, executing step 6;
and 5: inputting the position of the turbulence device, and repeating the steps 2 to 4;
step 6: establishing a sound field analysis model; calculating the sound field characteristics inside the cavity by using the calculated characteristics of the cavity pneumatic noise sound source as excitation conditions and utilizing an acoustic finite element or acoustic boundary element calculation method for the established sound field analysis model; the cavity interior sound field characteristics include an interior sound field sound pressure level and a sound field frequency.
2. The method according to claim 1, wherein the analysis conditions include gas density, gas temperature, sound velocity, gas flow velocity, flying height of the cavity, and cavity size.
3. The arrangement method of the cavity noise control device according to claim 1, wherein the cavity pneumatic noise source characteristics include an air flow density, a pressure, a velocity distribution inside the cavity, and a pulsating pressure of an inner surface of the cavity.
4. The arrangement method of the cavity noise control device according to claim 1, wherein the sound pressure level of the sound field inside the cavity is a change of distribution of pressure inside the cavity with time.
5. The arrangement method of the cavity noise control device according to claim 1, wherein the calculation method of the cavity aerodynamic noise sound source characteristic is a turbulence calculation using a separation vortex model, and the air flow velocity u of the turbulence is calculated i The calculation formula of (2) is as follows:
Figure FDA0002869707920000011
wherein
Figure FDA0002869707920000012
Is the vortex viscosity coefficient, ρ is the air flow density, u i Is the velocity of the gas stream, x j Is the coordinate, i, j ═ 1,2,3, σ v ,c b2 Is a constant value, S v Is a custom source item;
G v is a term for the generation of a turbulent viscosity,
Figure FDA0002869707920000013
wherein
Figure FDA0002869707920000014
κ,c b1 Is a constant, S is a tensor deformation scale,
Figure FDA0002869707920000015
Ω ij is the mean rate of rotation of the tensor,
Figure FDA0002869707920000016
Figure FDA0002869707920000017
is the length of the beam of light,
Figure FDA0002869707920000021
d is the distance of the grid from the wall, Δ max Is the maximum dimension of the grid, C des The empirical coefficient is 0.65;
Y v is a term for the reduction of the turbulent viscosity,
Figure FDA0002869707920000022
wherein
Figure FDA0002869707920000023
g＝r+c w2 (r 6 -r)，
Figure FDA0002869707920000024
c w1 ,c w2 ,c w3 Is a constant;
c b1 ＝0.1355,c b2 ＝0.622,σ v ＝2/3,
Figure FDA0002869707920000025
c w2 ＝0.3,c w3 ＝2.0,κ＝0.4187；
using a separation vortex model, based on the calculated air velocity u of the turbulent flow i The turbulent gas flow pressure, turbulent pressure and pulsating pressure of the inner surface of the cavity are derived.
6. The method as claimed in claim 1, wherein the spoiler is positioned at step 5
Figure FDA00028697079200000217
The calculation formula of (2) is as follows:
Figure FDA0002869707920000026
wherein p is i Is the pressure at the ith observation point inside the cavity; a. the 1 、A 2 Is a constant, determined analytically or experimentally;
Figure FDA0002869707920000027
is the position of the turbulence device away from the front edge of the cavity,
Figure FDA0002869707920000028
Figure FDA0002869707920000029
is the position of the observation point inside the cavity,
Figure FDA00028697079200000210
L 0 is the characteristic dimension of the cavity.
7. The arrangement method of the cavity noise control devices according to claim 6, wherein in the step 5, the characteristic dimension of the cavity comprises a cavity length L, or a cavity width W, or a cavity depth D.
8. The layout method of the cavity noise control devices according to claim 1, wherein in step 6, the sound pressure p inside the cavity is obtained by using an integral calculation formula of an acoustic finite element; wherein, the integral calculation formula of the acoustic finite element is as follows:
Figure FDA00028697079200000211
wherein p is the sound pressure inside the cavity,
Figure FDA00028697079200000212
is a function of the weight of the image,
Figure FDA00028697079200000213
q is the volume velocity per unit volume in the cavity. V is the cavity volume, Ω is the cavity surface, ρ 0 Is the airflow density, ω is the circular frequency, ω -2 pi f, f is the noise frequency,
Figure FDA00028697079200000216
is a vector of the velocity of the air flow,
Figure FDA00028697079200000214
is the cavity wall direction vector.
9. The arrangement method of the cavity noise control device according to claim 1, wherein in step 6, the sound pressure p inside the cavity is obtained by using an integral calculation formula of the acoustic boundary element; the calculation method of the acoustic boundary element comprises the following steps:
calculating the volume V of the cavity at any point not on the surface omega of the cavity
Figure FDA00028697079200000215
The sound pressure p is calculated by the formula:
Figure FDA0002869707920000031
and is
Figure FDA0002869707920000032
Wherein { C i And { D } i The elements of are respectively:
Figure FDA0002869707920000033
n a is the number of all nodes of the divided grid of the cavity surface,
Figure FDA0002869707920000034
is a function of the green's function,
Figure FDA0002869707920000035
Figure FDA0002869707920000036
satisfy the requirement of
Figure FDA0002869707920000037
N i Is a matrix of shape functions, N i Are respectively as
Figure FDA0002869707920000038
Wherein
Figure FDA0002869707920000039
And
Figure FDA00028697079200000310
respectively the sound pressure and normal velocity of a point inside a certain grid unit divided by the surface of the cavity pi And a vi Is the sound pressure and normal velocity at the unit node,
Figure FDA00028697079200000311
is an inner point of the grid cell, n e Is the grid cell omega a The number of nodes.
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