CN109141519B

CN109141519B - Test bench for testing acoustic and flow field characteristics of silencing element

Info

Publication number: CN109141519B
Application number: CN201810759480.8A
Authority: CN
Inventors: 郭荣; 汤铖; 赵翔宇; 付十豪; 韩帅; 王立婷
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2018-07-11
Filing date: 2018-07-11
Publication date: 2021-09-03
Anticipated expiration: 2038-07-11
Also published as: CN109141519A

Abstract

The invention relates to a test bench for testing acoustic and flow field characteristics of a silencing element, which comprises a fan, an air heater, a flow guide pipe, an air flow meter, a main pipe and a tail end silencer which are sequentially connected, wherein the silencing element to be tested is arranged in the middle of the main pipe, an air outlet of the fan is provided with a plurality of fan outlet noise silencers, the middle of the main pipe, which is positioned at the front end and the rear end of the silencing element to be tested, is symmetrically provided with test units for testing gas pressure, gas temperature and noise, the front end of the main pipe is provided with a branch pipe, one end of the branch pipe is provided with a loudspeaker, the test bench is provided with a controller, and the controller is connected with the loudspeaker, the test units and a flow sensor. Compared with the prior art, the device can measure the transmission loss and the pressure loss of the silencer to be measured in the flowing and different temperature environments by adding the controllable air source and the air heater and adjusting the flow and the temperature, can be used for measuring the transmission loss and the pressure loss of the automobile air inlet and exhaust silencer, and has the advantages of compact device and better universality.

Description

Test bench for testing acoustic and flow field characteristics of silencing element

Technical Field

The invention relates to industrial noise reduction, in particular to a test bench for testing acoustic and flow field characteristics of a silencing element

Background

With the increasing demand of consumers for the comfort of the automobile, the noise of the air intake and exhaust of the automobile has a considerable proportion in the noise of the whole automobile, and with the development of the high speed of the engine and the popularization of the turbocharged engine, the proportion of the noise of the air intake and exhaust system is increased, and in the measure of controlling the noise of the air intake and exhaust, the silencer is arranged to effectively attenuate the noise energy.

At present, all mufflers adopted by an air intake and exhaust system mainly comprise an expansion muffler, a Helmholtz muffler, an 1/4 wave pipe, a perforated muffler and the like, and during actual design, due to the fact that the appearance structure is complex, single theoretical calculation cannot well predict the transmission loss of the mufflers, from the experimental angle, the two-load method can well predict the transmission loss of the mufflers, and the measurement is accurate and reliable. But there is the unmatched problem of microphone interval irreconcilable silencer pipe diameter and measurement main pipe diameter among the traditional two carry method experimental apparatus, needs longer experiment preparation time during actual test.

From the current publications and related data, the transmission loss and the pressure loss of the silencer are separately tested, and the consistency of experimental conditions is difficult to guarantee. In addition, the test error of the test bench with flow transmission loss is large under the working condition of high-speed airflow, and airflow regeneration noise can occur. Therefore, in the present stage, a set of high-precision test bench for transmission loss and pressure loss of the silencing element in the flowing environment needs to be developed, so as to provide experimental verification for the theoretical research of acoustic characteristic and flow characteristic prediction of the irregular multi-cavity broadband silencer.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a test bench for testing the acoustic and flow field characteristics of a silencing element, which considers the changes of air flow and temperature.

The purpose of the invention can be realized by the following technical scheme: the utility model provides a test bench for noise elimination component acoustics and flow field characteristic test, this test bench is including fan, air heater, honeycomb duct, air flowmeter, the person in charge and the tail end muffler that connects gradually, and the amortization component that awaits measuring is installed the middle part of being responsible for, the air outlet of fan is equipped with a plurality of fan export noise mufflers, the person in charge middle part is located the front end and the rear end symmetry that await measuring the amortization component and is equipped with the test unit who is used for testing gas pressure, gas temperature and noise, the branch pipe is seted up to the front end of being responsible for, the one end of branch pipe is equipped with the speaker, the test bench is equipped with the controller, the controller is connected with speaker, test unit, flow sensor.

Preferably, the number of the fan outlet noise mufflers is at least 5. Set up a plurality of fan export noise silencers, can get rid of the noise that the fan produced, avoid producing the influence to the noise source of amortization component that awaits measuring.

The test unit comprises gas pressure gauges, temperature sensors and two microphones, the two gas pressure gauges located at the front end and the rear end of the to-be-tested silencing element are symmetrically arranged relative to the to-be-tested silencing element, the two temperature sensors located at the front end and the rear end of the to-be-tested silencing element are symmetrically arranged relative to the to-be-tested silencing element, and the four microphones located at the front end and the rear end of the to-be-tested silencing element are symmetrically arranged relative to the to-be-tested silencing element.

The controller comprises a data acquisition unit and a computer connected with the data acquisition unit, the data acquisition unit is connected with a gas pressure gauge, a temperature sensor, a microphone, a loudspeaker and an air flow meter, and the computer is connected with the fan.

The fan be equipped with the converter, the converter is connected with the computer.

The distance between the two microphones positioned in the same test unit is adjustable and is 15-160 mm. The spacing is selected to be different depending on the frequency of the noise emitted by the speaker, as shown in table 1.

TABLE 1 effective frequency Range at different microphone spacings

Microphone spacing/mm	Integrated effective frequency band/Hz
		15	[1133～4331]
20	[850～4331]
		25	[680～4331]
35	[486～3886]
		40	[425～3400]
55	[309～2472]
		60	[283～2267]
80	[213～1700]
		100	[170～1360]
120	[141～1133]
		140	[121～971]
160	[106～850]

The branch pipe is vertically connected with the main pipe, and the connection part is isolated by a thin film so as to avoid the influence of high-temperature and high-pressure gas on the work of the loudspeaker.

The tail end silencer is an anechoic guide tail pipe, so that the air flow is ensured to be uniform and stable while the sound is absorbed completely.

The working principle of the test bench is as follows:

the fan is located initial end, and the exit is connected with fan export noise silencer. The loudspeaker is positioned at the initial end of the branch pipe, and the branch pipe and the initial end of the main pipe are arranged at a right angle. White noise is generated by a speaker. The tail end of the main pipe is provided with a detachable tail end silencer which is an anechoic flow guide tail pipe and can ensure uniform and stable air flow while absorbing sound completely. Two different outlet boundary conditions are realized by disassembling and assembling the anechoic diversion tail pipe, and the two different outlet boundary conditions are used for calculating the transmission loss measurement by the two-load method. The front end of the main pipe is connected with an air flow meter, is connected with a data acquisition instrument, and adaptively adjusts the frequency of the fan through a computer, so that the air velocity in the pipeline of the whole test bench is ensured to be stabilized at a set value. Two microphone interfaces and a gas pressure gauge interface are uniformly arranged in front of and behind a silencer to be detected in the middle of the main pipe, a sound pressure signal measured by the microphone is connected to a data acquisition instrument, two times of data acquisition are carried out before and after the tail pipe is disassembled and assembled, and the transmission loss of the silencing element to be detected can be obtained based on a two-load method. And the gas pressure signal measured by the gas pressure gauge is also connected to the data acquisition and analysis system, so that the pressure loss of the silencing element is measured in real time.

Compared with the prior art, the invention has the beneficial effects that: the controllable air source and the air heater are added, the flow and temperature are adjusted during experiments, the transmission loss and the pressure loss of the silencer to be measured in the flowing environment and in the environment with different temperatures can be measured, the device can be used for measuring the transmission loss and the pressure loss of the automobile air inlet and outlet silencer, and is compact and good in universality.

Drawings

FIG. 1 is a schematic connection diagram of the present invention;

fig. 2 is an enlarged schematic view of a portion a in fig. 1.

The system comprises a frequency converter 1, a fan 2, an air inlet pipe 3, an air heater 4, a flow guide pipe 5, an air flow meter 6, a branch pipe 7, a main pipe 8, a loudspeaker 9, a tail end silencer 10, a gas pressure gauge 11, a temperature sensor 12, a microphone 13, an air filter 14, a fan outlet noise silencer 15, a computer 16, a data acquisition instrument 17 and a measured silencer 18.

Detailed Description

The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.

Example 1

The utility model provides a test bench for test of noise cancelling component acoustics and flow field characteristic, its structure is as shown in figure 1, figure 2, including fan 2 that connects gradually, air heater 4, honeycomb duct 5, air flowmeter 6, be responsible for 8 and tail end muffler 10, the noise cancelling component 18 that awaits measuring is installed in the middle part of being responsible for 8, the air outlet of fan 2 is equipped with 5 fan export noise mufflers 15, the front end and the rear end that are located the noise cancelling component 18 that awaits measuring in the middle part of being responsible for are equipped with the test unit that is used for testing gas pressure, gas temperature and noise to the symmetry, branch pipe 7 is seted up to the front end of being responsible for 8, the one end of branch pipe 7 is equipped with speaker 9, the test bench is equipped with the controller, controller and speaker 9, the test unit, flow sensor is connected. The fan outlet noise silencer 15 is connected with the air heater 4 through the air inlet pipe 3, the air inlet pipe 3 is connected with the air heater 4 through a flange, and the same flange interfaces are used among the air inlet pipe 3, the air heater 4, the flow guide pipe 5, the air flow meter 6 and the main pipe 8.

The testing unit comprises gas pressure gauges 11, temperature sensors 12 and microphones 13, the two gas pressure gauges 11 located at the front end and the rear end of the to-be-tested silencing element 18 are symmetrically arranged relative to the to-be-tested silencing element 18, the two temperature sensors 12 located at the front end and the rear end of the to-be-tested silencing element 18 are symmetrically arranged relative to the to-be-tested silencing element 18, and the four microphones 13 located at the front end and the rear end of the to-be-tested silencing element 18 are symmetrically arranged in pairs relative to the to-be-tested silencing element 18.

The controller comprises a data acquisition unit 17 and a computer 16 connected with the data acquisition unit 17, the data acquisition unit 17 is connected with the gas pressure gauge 11, the temperature sensor 12, the microphone 13, the loudspeaker 9 and the air flow meter 6, and the computer 16 is connected with the fan 2.

The fan 2 is provided with a frequency converter 1, the frequency converter 1 is connected with a computer 16, and an inlet facility air filter 14 of the fan 2.

The branch pipe 7 is vertically connected with the main pipe 8, and the connection part is isolated by a film so as to avoid the influence of high-temperature and high-pressure gas on the operation of the loudspeaker 9. The tail end silencer 10 is an anechoic guide tail pipe, and can ensure uniform and stable air flow while absorbing sound completely.

Claims

1. A test bench for testing acoustic and flow field characteristics of a silencing element is characterized by comprising a fan, an air heater, a flow guide pipe, an air flow meter, a main pipe and a tail end silencer which are sequentially connected, wherein the silencing element to be tested is installed in the middle of the main pipe, a plurality of fan outlet noise silencers are arranged at an air outlet of the fan, and test units for testing gas pressure, gas temperature and noise are symmetrically arranged at the front end and the rear end of the silencing element to be tested in the middle of the main pipe;

the testing unit comprises gas pressure gauges, temperature sensors and two microphones, the two gas pressure gauges positioned at the front end and the rear end of the silencing element to be tested are symmetrically arranged relative to the silencing element to be tested, the two temperature sensors positioned at the front end and the rear end of the silencing element to be tested are symmetrically arranged relative to the silencing element to be tested, and the four microphones positioned at the front end and the rear end of the silencing element to be tested are symmetrically arranged in pairs relative to the silencing element to be tested;

the front end of the main pipe is provided with a branch pipe, one end of the branch pipe is provided with a loudspeaker, the test bench is provided with a controller, and the controller is connected with the loudspeaker, the test unit and the flow sensor;

TABLE 1

The distance between the two microphones positioned in the same test unit is 15-160 mm, and the distance is adjusted according to the table 1.

2. The test bench for acoustic and flow field characterization of sound attenuating elements according to claim 1, wherein the number of fan outlet noise attenuators is at least 5.

3. The test bench for testing the acoustic and flow field characteristics of the silencing element according to claim 1, wherein the controller comprises a data collector and a computer connected with the data collector, the data collector is connected with the gas pressure gauge, the temperature sensor, the microphone, the loudspeaker and the air flow meter, and the computer is connected with the fan.

4. The test bench for testing the acoustic and flow field characteristics of the muffling element according to claim 3, wherein the fan is provided with a frequency converter, and the frequency converter is connected with a computer.

5. A test rig for acoustic and flow field characterization of a sound damping element according to claim 1, wherein the branch pipe is connected perpendicularly to the main pipe and is separated at the connection by a membrane.

6. The test rig for acoustic and flow field characterization of a muffling element of claim 1, wherein the tail muffler is an anechoic tail pipe.