CN107782523A - A kind of new cavity modal noise standing wave decomposition method - Google Patents

A kind of new cavity modal noise standing wave decomposition method Download PDF

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CN107782523A
CN107782523A CN201711047016.8A CN201711047016A CN107782523A CN 107782523 A CN107782523 A CN 107782523A CN 201711047016 A CN201711047016 A CN 201711047016A CN 107782523 A CN107782523 A CN 107782523A
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noise
standing wave
modal noise
modal
cavity
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CN107782523B (en
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杨党国
周方奇
路波
吴军强
刘俊
王显圣
施傲
杨野
郑晓东
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High Speed Aerodynamics Research Institute of China Aerodynamics Research and Development Center
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High Speed Aerodynamics Research Institute of China Aerodynamics Research and Development Center
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M9/00—Aerodynamic testing; Arrangements in or on wind tunnels
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M9/00—Aerodynamic testing; Arrangements in or on wind tunnels
    • G01M9/02—Wind tunnels
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • 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 discloses a kind of new cavity modal noise standing wave decomposition method, comprise the following steps：Step 1: being decomposed using the spectrum signature of the fluctuation pressure data of the different measuring points of cavity floor to modal noise, the spatial distribution of different modalities noise amplitude is obtained；Step 2: the form of mode standing wave is determined using the spatial distribution of cavity floor modal noise amplitude.Compared with prior art, the positive effect of the present invention is：The present invention is directed to the fluctuation pressure data in cavity inner wall face, propose a kind of new modal noise standing wave analysis method, the inventive method extracts spatial distribution of the different modalities noise in intracavitary using the acoustic pressure frequency spectrum at cavity wall measuring point, and passes through the standing wave regularity of distribution of standing wave theory Analysis Mode noise.

Description

A kind of new cavity modal noise standing wave decomposition method
Technical field
The present invention relates to experimental fluid mechanics field, and in particular to a kind of new cavity modal noise standing wave decomposition method, Realized by decomposition of the formation to cavity standing wave with propagating physical process special to mode noise profile rule in cavity and radiation Sign is analyzed.
Background technology
When high velocity air passes through cavity, because flow separation forms shear layer above chamber, multiple dimensioned rotation in shear layer be present The generation and motion in whirlpool, the noise for producing high intensity is hit with cavity trailing edge, can not only cause the vibration of cavity structure, bring knot Structure fatigue rupture, and then the service life and safety of structure are influenceed, but also the normal operation of equipment in aircraft can be influenceed, separately Outer noise pollution also results in the health of personnel.Therefore, the mechanism of production to modal noise in cavity and propagation law research meaning Justice is great.
Noise in cavity mainly contains two parts, and a part is due to that the stream that the micelle motion in fluid triggers causes to make an uproar Sound (turbulence noise), belongs to wideband random noise；Another part is that Shedding Vortex periodically hits production to cavity trailing edge in shear layer Raw modal noise, belong to the peak noise with typical excited frequency, the energy of wherein modal noise is usually higher, frequency Feature is more apparent, easily causes mesomerism, and the emphasis of research and suppression.Turbulence noise occurs mainly with non-fixed in flow field Often disturbance, the mainly external radiation into cavity by shear layer, and modal noise is then mainly from trailing edge upward propagation forward, thus two Kind noise interacts and is superimposed when intracavitary is moved, so as to form the complicated noise profile feature of intracavitary and propagation law.
During wind tunnel test, the pressure fluctuation in flow field nearby is gathered by the oscillatory pressure pick-up of cavity wall, Wherein contain direct current and exchange two kinds of compositions.Processing removes flip-flop after filtering, retains alternating component p (t), under Formula calculates its root mean square：
So as to obtain the overall sound pressure level SPL of fluctuation pressure time domain samples：
Wherein T is sample length, prefFor reference pressure 2.0 × 10-5Pa.Overall sound pressure level at different measuring points, which reflects, makes an uproar Sound intensity provides certain support in the overall distribution situation of intracavitary, can be made an uproar for research intracavitary sonic propagation and development.But Both stream broadening frequency discrete noise had been contained in overall sound pressure level, multi-modes noise has been also contains, can not therefrom reflect high intensity The distribution situation of main composition-modal noise in noise.
Analysis for intracavitary modal noise, the method typically used are to carry out Fourier's change to fluctuation pressure time domain data Change, obtain power spectral density PSD of the fluctuation pressure on frequency domain, it is acoustic pressure then to calculate sound pressure level distribution of the noise on frequency domain Frequency spectrum SPFS：
Acoustic pressure frequency spectrum reflects the distribution situation on noise intensity different frequency, wherein due to pure tone form modal noise Intensity is much larger than wideband discrete noise, and strong sharp peaks characteristic is shown in spectrum curve, thus divides from the peak value in curve Cloth feature can extract the frequency and amplitude of different modalities noise.Acoustic pressure frequency spectrum reflects distribution shape of the noise in frequency Condition, but it is just for the data of single measuring point, thus the distribution situation of modal noise spatially can not be reflected.
The content of the invention
In order to overcome the disadvantages mentioned above of prior art, the present invention proposes a kind of new cavity modal noise standing wave decomposition side Method.
The technical solution adopted for the present invention to solve the technical problems is：A kind of new cavity modal noise standing wave decomposition side Method, comprise the following steps：
Step 1: modal noise is divided using the spectrum signature of the fluctuation pressure data of the different measuring points of cavity floor Solution, obtain the distribution of different modalities noise amplitude spatially；
Step 2: the form of mode standing wave is determined using the spatial distribution of cavity floor modal noise amplitude.
Compared with prior art, the positive effect of the present invention is：
The present invention is directed to the fluctuation pressure data in cavity inner wall face, it is proposed that a kind of new modal noise standing wave analysis side Method, the inventive method extract spatial distribution of the different modalities noise in intracavitary using the acoustic pressure frequency spectrum at cavity wall measuring point, And pass through the standing wave regularity of distribution of standing wave theory Analysis Mode noise.
Brief description of the drawings
Examples of the present invention will be described by way of reference to the accompanying drawings, wherein：
Fig. 1 is that cavity mode sound wave is superimposed schematic diagram；
Fig. 2 is cavity floor different measuring points acoustic pressure spectrum distribution；
Fig. 3 is the distribution map of each rank modal noise amplitude of cavity floor；
Fig. 4 is the curve matching of each rank modal noise amplitude spatially.
Embodiment
The present invention proposes a kind of new cavity modal noise standing wave decomposition method, utilizes mode in standing wave theory analysis cavity The regularity of distribution of noise, including following content：
1) modal noise decomposes
Spectrum analysis is carried out for the time-domain information that oscillatory pressure pick-up obtains, because modal noise mainly produces from trailing edge It is raw, thus from the acoustic pressure frequency spectrum of fluctuation pressure at trailing edge measuring point, different modalities noise is told by the peak feature of curve Frequency and sound pressure amplitude.Modal noise is propagated in intracavitary in the form of a sound wave, and its frequency is basic in communication process to be kept not Become, thus the sound pressure level of same modal frequency causes by the modal noise in different measuring points in intracavitary noise, modal frequency Sound pressure level reflects intensity of the modal noise in point position.By the sound pressure level of modal frequency at different measuring points, and combine The position of measuring point can obtain spatial distribution state of the modal noise intensity in intracavitary.Divided for different modalities frequency noise Analysis, the sound pressure level of modal noise is extracted at different measuring points using each rank modal frequency, you can obtain different modalities noise and exist The distribution situation of intracavitary, realize the decomposition to intracavitary modal noise.
2) standing wave analysis of modal noise distribution
Modal noise is mainly produced from cavity trailing edge and upward propagation forward, and when being collided with antetheca, a part of sound wave can be sent out Raw reflection, its frequency and velocity of wave are held essentially constant after reflection, and the sound wave of up modal waves and reflection is superimposed can be in intracavitary shape Into standing wave, thus the regularity of distribution of modal noise can be analyzed by standing wave theory.
As shown in figure 1, Simplified analysis is carried out to communication process of a certain mode sound wave in the intracavitary that length is L, it is assumed that its Frequency is f, and the amplitude of sound wave is being propagated and do not decayed in reflection process, remains A0.The mode sound of upward propagation Ripple is reduced to：
The mode sound wave reflected through antetheca is reduced to：
Up sound wave is superimposed to the distribution that can obtain modal noise in intracavitary with reflection sound wave：
Wherein A1For the amplitude of standing wave：
The amplitude of standing wave is unrelated with the time, and spatially in cosine distribution, wherein λ=u/f represents standing wave amplitude in space On wavelength.
By being found after carrying out mode decomposition to intracavitary noise, the amplitude of each rank modal noise is then basic upwards in intracavitary exhibition It is constant, and be then distributed in flow direction in wave, change wavelength reduces with the increase of modal frequency.Modal noise amplitude is flowing Upward distribution is consistent with stationary wave characteristic, thus intracavitary modal noise is analyzed using standing wave formula, so as to obtain mode The standing wave regularity of distribution of the noise in intracavitary.
Below by way of length L=200mm under Ma1.5 inlet flow conditions, long depth-to-width ratio example is 6:1:The wind tunnel test knot of 2 cavitys Exemplified by fruit analysis, specific steps are introduced to realize.
Step 1: the decomposition of modal noise：
(1) for cavity floor different measuring points time domain ripple pressure data result, using Fourier transformation by its turn The acoustic pressure frequency spectrum of frequency domain is changed to, and is depicted as spectrum curve (Fig. 2)；
(2) sharp peaks characteristic in spectrum curve extracts the frequency and amplitude (table 1 and 2) of different modalities noise；
(3) position of fluctuation pressure measuring point is combined, obtains the spatial distribution of different modalities noise amplitude.
Each rank modal frequency of Ma1.5 space-time intracavitary of table 1
First-order modal frequency Second-order modal frequency Three rank modal frequencies
531Hz 1275Hz 2044Hz
The amplitude of each rank modal noise at the Ma1.5 space-time intracavitary different measuring points of table 2
Step 2: determine the form of mode standing wave：
(1) spatial distribution of cavity floor modal noise amplitude is utilized, the change for drawing out each rank modal noise amplitude is bent Line (Fig. 3)；
(2) according to the change curve of modal noise amplitude, with reference to the standing wave regularity of distribution, the distribution letter of modal noise is constructed Number：Y=(aX+b) cos (cX+d)+eX+f, wherein y represent the amplitude change of modal noise, and unit dB, X represent space Change, using nondimensionalization length X=x/L, L is that cavity length 200mm, x are physical location, unit mm, a, b, c, d, e and F is parameter to be asked.
(3) by Matlab softwares built in fitting tool, use the spatial distribution of above-mentioned function pair modal noise amplitude It is fitted, so that it is determined that respectively parameter to be asked in function, and each rank modal noise is in the distribution form of intracavitary, as a result such as Fig. 4 It is shown：
y1=(- 4.5X-4.0) cos (7.6X+3.0)+3.78X+129.6
y2=(- 6.1X+9.57) cos (14.23X+6.2)+8.6X+142.5
y3=(4.5X+1.4) cos (- 18.51X-13)+10.3X+124.1

Claims (6)

  1. A kind of 1. new cavity modal noise standing wave decomposition method, it is characterised in that：Comprise the following steps：
    Step 1: modal noise is decomposed using the spectrum signature of the fluctuation pressure data of the different measuring points of cavity floor, Obtain the spatial distribution of different modalities noise amplitude；
    Step 2: the form of mode standing wave is determined using the spatial distribution of cavity floor modal noise amplitude.
  2. A kind of 2. new cavity modal noise standing wave decomposition method according to claim 1, it is characterised in that：Step 1 institute Stating the method decomposed to modal noise is：
    (1) the time domain ripple pressure data of the different measuring points of cavity floor is converted to the acoustic pressure frequency of frequency domain using Fourier transformation Spectrum, and it is depicted as spectrum curve；
    (2) frequency and amplitude of different modalities noise are extracted from spectrum curve；
    (3) position of fluctuation pressure measuring point is combined, obtains the spatial distribution of different modalities noise amplitude.
  3. A kind of 3. new cavity modal noise standing wave decomposition method according to claim 2, it is characterised in that：It is bent from frequency spectrum The frequency of different modalities noise and the method for amplitude are extracted in line to be extracted using the sharp peaks characteristic of spectrum curve.
  4. A kind of 4. new cavity modal noise standing wave decomposition method according to claim 1, it is characterised in that：Step 2 institute State and determine that the method for form of mode standing wave is：
    (1) spatial distribution of cavity floor modal noise amplitude is utilized, draws out the change curve of each rank modal noise amplitude；
    (2) according to the change curve of modal noise amplitude, the distribution function of modal noise is constructed；
    (3) by Matlab softwares built in fitting tool, utilize distribution function to carry out the spatial distribution of modal noise amplitude Fitting, so that it is determined that respectively parameter to be asked in distribution function, and each rank modal noise is in the distribution form of intracavitary.
  5. A kind of 5. new cavity modal noise standing wave decomposition method according to claim 4, it is characterised in that：The mould of construction The distribution function of state noise is y=(aX+b) cos (cX+d)+eX+f, and wherein y represents the amplitude change of modal noise, unit The change in space is represented for dB, X, a, b, c, d, e and f are parameter to be asked.
  6. A kind of 6. new cavity modal noise standing wave decomposition method according to claim 5, it is characterised in that：The X= X/L, using nondimensionalization length, wherein L is cavity length, and x is physical location, and unit is mm.
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Cited By (5)

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CN109724764A (en) * 2019-03-11 2019-05-07 中国人民解放军国防科技大学 Experimental device and method for evaluating noise of wind tunnel flow field
CN110287607A (en) * 2019-06-27 2019-09-27 淮阴师范学院 A kind of method of integrated modeling and system of cavity noise generation and propagation law
CN111564149A (en) * 2020-04-30 2020-08-21 中国飞机强度研究所 Cavity structure noise control method and device based on controllable impedance boundary
CN111766039A (en) * 2020-07-10 2020-10-13 中国空气动力研究与发展中心高速空气动力研究所 Method for calculating measurement result of compressible fluid disturbance mode of subsonic wind tunnel
CN112549868A (en) * 2020-12-23 2021-03-26 青岛森麒麟轮胎股份有限公司 Detection and analysis method for tire cavity noise and application thereof

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109724764A (en) * 2019-03-11 2019-05-07 中国人民解放军国防科技大学 Experimental device and method for evaluating noise of wind tunnel flow field
CN110287607A (en) * 2019-06-27 2019-09-27 淮阴师范学院 A kind of method of integrated modeling and system of cavity noise generation and propagation law
CN111564149A (en) * 2020-04-30 2020-08-21 中国飞机强度研究所 Cavity structure noise control method and device based on controllable impedance boundary
CN111564149B (en) * 2020-04-30 2023-11-21 中国飞机强度研究所 Cavity structure noise control method and device based on controllable impedance boundary
CN111766039A (en) * 2020-07-10 2020-10-13 中国空气动力研究与发展中心高速空气动力研究所 Method for calculating measurement result of compressible fluid disturbance mode of subsonic wind tunnel
CN111766039B (en) * 2020-07-10 2022-04-15 中国空气动力研究与发展中心高速空气动力研究所 Method for calculating measurement result of compressible fluid disturbance mode of subsonic wind tunnel
CN112549868A (en) * 2020-12-23 2021-03-26 青岛森麒麟轮胎股份有限公司 Detection and analysis method for tire cavity noise and application thereof
CN112549868B (en) * 2020-12-23 2022-05-27 青岛森麒麟轮胎股份有限公司 Detection and analysis method for tire cavity noise and application thereof

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