CN113281049A - Fan pipeline sound mode simulation device under incoming flow condition - Google Patents
Fan pipeline sound mode simulation device under incoming flow condition Download PDFInfo
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- CN113281049A CN113281049A CN202110505057.7A CN202110505057A CN113281049A CN 113281049 A CN113281049 A CN 113281049A CN 202110505057 A CN202110505057 A CN 202110505057A CN 113281049 A CN113281049 A CN 113281049A
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- G—PHYSICS
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M15/00—Testing of engines
- G01M15/02—Details or accessories of testing apparatus
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- 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
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
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Abstract
一种有来流条件下风扇管道声模态模拟装置，包括发动机简化模型、扬声器、声衬安装区、整流罩、传声器、短舱外壳、翼型支撑、翼型支撑片，发声控制系统和PXi采集系统，发动机简化模型通过翼型支撑片与短舱外壳连接，在所述的翼型支撑片前方，短舱外壳上沿圆周按一定间隔安装多个扬声器，在所述的扬声器前方，短舱外壳内设有声衬安装区，用来安装消声声衬试验样件，短舱外壳唇口附近，沿短舱外壳内壁面等距固定安装有多个传声器；本发明利用电声源信号模拟风扇噪声，从而满足带来流条件下的风扇前传噪声测量需求，测量不同风速下声衬的降噪性能。相比于传统流管测试法更接近实际应用，提高了试验效率。
A fan duct acoustic modal simulation device under inflow conditions, including a simplified model of the engine, loudspeaker, acoustic lining installation area, fairing, microphone, nacelle shell, airfoil support, airfoil support sheet, sound control system and PXi In the acquisition system, the simplified model of the engine is connected to the nacelle shell through the airfoil support piece. In front of the airfoil support piece, a plurality of speakers are installed on the nacelle shell at certain intervals along the circumference. In front of the speakers, the nacelle There is an acoustic lining installation area in the outer casing, which is used to install the test sample of the anechoic lining. Near the lip of the nacelle casing, a plurality of microphones are fixedly installed at equal distances along the inner wall of the nacelle casing; the present invention uses the electro-acoustic source signal to simulate the fan Noise, so as to meet the requirements of fan front-pass noise measurement under the condition of brought flow, and measure the noise reduction performance of the acoustic lining under different wind speeds. Compared with the traditional flow tube test method, it is closer to practical application and improves the test efficiency.
Description
Technical Field
The invention belongs to the technical field of noise measurement, and particularly relates to a fan pipeline sound mode simulation device under the condition of incoming flow.
Background
When the noise reduction of the fan noise of the aircraft engine is researched, it is important to research how to measure the mode of the fan noise transmitted from the front of the engine. At present, most of common measurement pipeline acoustic modal devices at home and abroad are under the acoustic theoretical research in a no-incoming-flow state, and mostly adopt a cylindrical pipeline structure, so that the comprehensive consideration of pneumatics and acoustics is lacked.
In the prior art, a method for measuring the acoustic mode of an engine pipeline generally adopts that an annular pipeline device is arranged at an inlet and an outlet of the engine pipeline, and an anechoic chamber test is performed on the center of an engine, or a motor-driven engine model is used for scanning rake sensor measurement in an anechoic chamber. For the above methods, there are interference flow effects or unnecessary noise sources added when testing under the condition of incoming flow. Therefore, a technical scheme is needed to be suitable for wind tunnel tests and measure the acoustic modal parameters of the pipeline of the nacelle structure.
Disclosure of Invention
The invention provides a fan pipeline sound mode simulation device under the condition of incoming flow, which simulates fan noise by using an electroacoustic source signal, thereby meeting the measurement requirement of fan forward-transmitted noise under the condition of incoming flow and measuring the noise reduction performance of a sound liner under different wind speeds.
The technical scheme adopted by the invention is as follows: a fan pipeline sound mode simulation device under the condition of incoming flow comprises an engine simplified model, a loudspeaker, a sound lining installation area, a fairing, a microphone, a nacelle shell, a wing section support sheet, a sound production control system and a PXi acquisition system,
the engine simplified model is connected with a nacelle shell through a wing type supporting sheet, the nacelle shell is connected with an acoustic wind tunnel wing type supporting device through a wing type support, the wing type support is used for supporting and fixing the whole nacelle model and reducing the pneumatic noise influence caused by interference on incoming flow, the wing type support is vertically and fixedly connected to a wind tunnel test stand, so that the nacelle model is stable in strength during a wind tunnel test, and the wing type supporting sheet adopts a wing type structure to reduce the pneumatic noise influence on air flow interference in the nacelle model;
a plurality of loudspeakers are arranged in front of the wing section supporting sheet on the nacelle shell at certain intervals along the circumference, and the phase and amplitude of the loudspeakers are controlled by a sound production control system and are used for synthesizing and simulating a circumferential sound mode generated by a fan so as to realize the simulation of a pipeline sound mode;
in front of the loudspeaker, a sound lining installation area is arranged in the nacelle shell and used for installing a sound-deadening sound lining test sample piece, a sound-absorbing hole of the sound lining is flush with the inner wall surface of the nacelle shell, the sound-deadening sound lining test sample piece is sealed by a cover plate when the sound lining is measured, and the sound-absorbing hole of the sound-deadening sound lining test sample piece is flush with the inner wall surface of the nacelle shell;
a plurality of microphones are fixedly arranged in front of the sound lining mounting area and near the lip of the nacelle shell at equal intervals along the inner wall surface of the nacelle shell;
a fairing is arranged outside the nacelle shell and comprises a loudspeaker and a projecting part of a microphone to prevent the loudspeaker and the sensor from being exposed in a flow field, and connecting cables are converged in the fairing and penetrate through the wing-shaped support to be respectively connected with an external sound production control system and a PXi acquisition system through electric signals;
an acoustic mode simulation control program is installed in the sounding control system and used for setting the amplitude and phase of each loudspeaker, finally high-sound-intensity plane waves are emitted by the loudspeakers, and the high-sound-intensity plane waves are axially synthesized in the nacelle shell and transmitted to the downstream of the flow field; the PXi acquisition system acquires time domain signals through a plurality of microphones, respectively measures sound pressure fluctuation quantities of measurement points in a non-acoustic lining state and an acoustic lining state, obtains a main mode amplitude and a circumferential mode order after decomposition through a space Fourier method, and compares the main mode amplitude and the circumferential mode order to obtain the sound absorption effect of the acoustic lining in a specific mode.
In order to enable the sound pressure level to meet the test standard, through holes are designed on the surface of the nacelle shell to form the equal-section wave guide pipes. Since the speaker's ability to emit sound is concentrated in the throat, the waveguide size is consistent with the speaker's throat diameter. The sounding amplitudes of the loudspeakers are consistent, and the phase difference of the adjacent loudspeakers is the same, so that the sounding requirement of simulating the sound mode of the fan pipeline can be met.
The invention has the advantages that: the invention simulates the fan noise by using the electroacoustic source signal, thereby meeting the measurement requirement of fan forward noise under the current-carrying condition and measuring the noise reduction performance of the acoustic liner under different wind speeds. The device can be used for testing the sound absorption effect of the sound liner on the noise of the engine fan under the condition of incoming flow, is closer to practical application compared with the traditional flow pipe testing method, simultaneously avoids the problem of low testing efficiency of the sound liner installed on a real engine, and improves the testing efficiency.
Drawings
Fig. 1 is a cross-sectional view of a fan duct acoustic mode simulation apparatus under an incoming flow condition according to an embodiment of the present invention.
Fig. 2 is a cross-sectional view of the speaker position of section a in fig. 1.
Fig. 3 is a schematic diagram of the sound source simulation apparatus controlling the speaker to sound.
FIG. 4 is a flowchart of an acoustic simulation control process for a fan duct.
Detailed Description
The invention is further illustrated by way of example in the accompanying drawings of the specification:
example 1
As shown in fig. 1-2, a fan duct acoustic modal simulation apparatus under an incoming flow condition includes an engine simplified model 1, a speaker 2, an acoustic liner installation region 3, a fairing 4, a microphone 5, a nacelle housing 6, a wing support 7, a wing support sheet 8, a sound production control system and a PXi acquisition system, wherein the engine simplified model 1 is connected with the nacelle housing 6 through the wing support sheet 8, and the nacelle housing 6 is connected with an acoustic wind tunnel wing support apparatus through the wing support 7; in front of the wing section supporting sheet 8, a plurality of loudspeakers 2 are arranged on the nacelle shell 6 at certain intervals along the circumference, and the phases and amplitudes of the loudspeakers are controlled by a sounding control system, so that circumferential acoustic modes generated by a fan are synthesized and simulated, and the simulation of the pipeline acoustic modes is realized;
the sound liner installation area 3 is arranged in front of the loudspeaker 2 along the axial direction and in the nacelle shell 6 and used for installing a sound-absorbing sound liner test sample piece and measuring the noise reduction performance of the sound liner at different wind speeds; when the anechoic lining test sample piece is measured, the anechoic lining test sample piece is sealed by a cover plate;
the nacelle housing is divided into two sections at the acoustic liner mounting section for ease of mounting the acoustic liner, connected by rivets. The nacelle shell is in threaded connection with the fairing.
A plurality of microphones 5 are fixedly arranged in front of the acoustic liner mounting area along the axial direction and near the lip of the nacelle shell 6 at equal intervals along the inner wall surface of the nacelle shell 6;
a fairing 4 is arranged outside the nacelle shell 6 and comprises a part where the loudspeaker 2 and the microphone 5 protrude, and connecting cables are converged in the fairing 4 and penetrate through a wing-shaped support 7 to be respectively connected with an external sound production control system and a PXi acquisition system through electric signals;
an acoustic mode simulation control program is installed in the sounding control system and used for setting the amplitude and phase of each loudspeaker 2, finally, the loudspeakers 2 emit high-sound-intensity plane waves, the fan acoustic modes are axially synthesized in the nacelle shell and transmitted to the downstream of the flow field; the PXi acquisition system acquires time domain signals through a plurality of microphones, respectively measures sound pressure fluctuation quantities of measurement points in a non-acoustic lining state and an acoustic lining state, obtains a main mode amplitude and a circumferential mode order after decomposition through a space Fourier method, and compares the main mode amplitude and the circumferential mode order to obtain the sound absorption effect of the acoustic lining in a specific mode.
The surface of the nacelle shell 6 is provided with a plurality of through holes which are used as equal-section wave guide pipes 10, and the size of each wave guide pipe is consistent with the throat diameter 9 of the loudspeaker 2.
The sound absorption hole of the sound attenuation lining test sample piece is flush with the inner wall surface of the nacelle shell 6.
The fairing is annular and slightly larger than the outer diameter of the nacelle housing so that the speaker and the sensor can be enclosed therein. By arranging the loudspeaker near the wing section supporting sheet and utilizing the fan pipeline acoustic mode synthesis principle, a sound source emitted by forward noise of the analog fan can be controlled; by arranging the sensor near the lip and utilizing the space Fourier decomposition principle, the circumferential sound modal order and the sound pressure level of the fan front-transmitted noise subjected to sound liner sound absorption can be detected.
Fig. 3 is a schematic diagram of controlling speaker sounding. The sound production control system adopts an industrial personal computer to control a sound card 13 to output voltage signals to a driver audio processor 12, the driver audio processor controls 4 power amplifiers 11, and each power amplifier 11 controls 4 loudspeakers 2 to produce sound. The sound wave emitted by each loudspeaker 2 is regarded as plane wave, and each loudspeaker 2 is provided with two frequency dividing lines for controlling sound production and can emit medium and low frequency sound wave. The whole cabinet is placed outside the wind tunnel flow field.
Fig. 4 is a flow chart of a fan duct acoustic simulation control program developed using a Labview graphical programming language, having a GUI interface, capable of inputting a circumferential modal order m, selecting a corresponding signal output channel, sampling a clock, determining a sampling frequency and a maximum voltage amplitude, determining a specific driving signal for each speaker, and calibrating and compensating the amplitude and phase of the speaker one by one. The program should be used in conjunction with hardware devices such as NI data controllers, power amplifiers, speakers, etc. The program is divided into four modules according to functions:
a first module: and setting signal parameters, selecting a corresponding signal output channel in the module, sampling a clock, and determining a sampling frequency and a maximum voltage amplitude.
And a second module: and setting a synthetic mode, wherein the order m, the frequency and the corresponding intensity of the synthetic circumferential mode are required to be specified in the module. The total number of the loudspeakers is set, the phase difference of signals between two adjacent loudspeakers can be determined according to the input modal order, and then the specific driving signal of each loudspeaker can be determined according to the set signal frequency and the set signal amplitude. Which drives the speaker to sound through the power amplifier.
And a third module: the calibration parameters of the loudspeakers are input, and the loudspeakers do not correspond to the driving signals perfectly due to the difference of the loudspeakers, so that the amplitude and the phase difference of the loudspeaker array cannot be completely consistent, and calibration and compensation may be needed. If the loudspeaker quality is good, the amplitude and phase difference generally has little influence on the final synthesized modal quality, calibration can be omitted, and the corresponding supplementary constant is set to be zero.
And a module IV: and the signal display output is used for displaying a final output signal, so that a user can conveniently check and confirm the signal state and check possible faults.
The acoustic simulation control program is used for inputting the circumferential modal order m, selecting a corresponding signal output channel, sampling a clock, determining a sampling frequency and a maximum voltage amplitude, determining a specific driving signal of each loudspeaker, calibrating and compensating the amplitude and the phase of the loudspeaker one by one,
the PXi acquisition system acquires time domain signals through a microphone and obtains a main mode amplitude and a circumferential mode order after decomposition through a space Fourier method.
Example 2
The main test steps of the invention for measuring the sound mode of the fan pipeline in the wind tunnel comprise the following steps:
the method comprises the following steps: and opening the cover plate of the acoustic liner mounting section, and mounting the tested acoustic liner test piece. The sound liner test piece is of an annular structure, and the nacelle shell can be divided into two sections in the sound liner mounting area. And (3) splitting the nacelle shell, clamping the sound lining test piece into the groove, and finally connecting the two sections of nacelle shells by using rivets.
Step two: and connecting the nacelle shell with a fairing, a wing section support sheet, an engine simplified model and a wing section support, and moving the nacelle shell to a wind tunnel test platform, wherein the engine simplified model corresponds to the center of a wind tunnel collector.
Step three: and the fan pipeline acoustic simulation device is connected, the cabinet is connected with the loudspeaker cable, and the cabinet is placed outside the wind tunnel. 16 loudspeakers are controlled to sound through a main control system, the sound emission amplitude of each loudspeaker is consistent, and the phase difference of adjacent loudspeakers is increased progressively. Thus, the sound source mode with the circumferential modal order of 8 can be synthesized.
Step four: and the synthesized sound source is transmitted to the downstream of the nacelle model along the incoming flow direction, and the sensor receives the time domain signal and obtains the main mode amplitude and the circumferential mode order after spatial Fourier decomposition.
Step five: and (4) under the state of a soundless lining (mounting a cover plate), repeating the test measurement according to the steps from two to four, measuring the sound pressure amplitude of the measurement point under the state of the soundless lining, and comparing the measured sound pressure amplitude with the sound lining under the test condition to obtain the sound lining sound absorption effect.
The steps are 8-order circumferential modal synthesis and acoustic liner testing schemes, and the steps can be correspondingly modified according to the steps if the order of the tested sound source and the acoustic liner sample piece need to be replaced. Finally, it should be pointed out that: the above embodiments are only used to illustrate the technical solutions of the present solution, and not to limit the same. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will appreciate that the present invention is not limited thereto. Modifications of the technical solutions described in the embodiments or equivalent replacements of some technical features may still be made. And the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
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Cited By (2)
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| CN115371947A (en) * | 2022-08-23 | 2022-11-22 | 中国航空工业集团公司哈尔滨空气动力研究所 | Wing/fan installation effect fan nacelle simulation device for wind tunnel noise test |
| CN115614309A (en) * | 2021-12-30 | 2023-01-17 | 西安交通大学 | Circumferential acoustic modal measurement method of aero-engine based on Lp norm regularization |
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