CN100559144C - Open closed formula is pneumatic-the low frequency structure for restraining flutter of acoustic wind tunnel - Google Patents
Open closed formula is pneumatic-the low frequency structure for restraining flutter of acoustic wind tunnel Download PDFInfo
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- CN100559144C CN100559144C CNB2007100938642A CN200710093864A CN100559144C CN 100559144 C CN100559144 C CN 100559144C CN B2007100938642 A CNB2007100938642 A CN B2007100938642A CN 200710093864 A CN200710093864 A CN 200710093864A CN 100559144 C CN100559144 C CN 100559144C
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Abstract
The invention discloses a kind of open closed formula pneumatic-the low frequency structure for restraining flutter of acoustic wind tunnel, described wind-tunnel is successively by blower fan, the blower fan diffuser, the 3rd turning, heat interchanger, the 4th turning, honeycomb, damping screen, contraction section, spout, jet segment, collect mouth, diffuser, first turning, first transition section, second turning and blower fan wind inlet section are formed, spout wherein, jet segment and collection mouth all are contained in wind-tunnel and stay indoor, at a diffuser that links to each other with the collection mouth, first turning, the top at first transition section and second turning is provided with cavity structure, and described cavity structure is provided with a plurality of air vents and wind-tunnel runner, staying the chamber communicates.The present invention has reduced the low frequency flutter, improves the experimental measurement environment of test section flow field and sound field.
Description
Technical field
The present invention relates to the pneumatic acoustic wind tunnel of a kind of open closed formula, particularly relate to the low frequency structure for restraining flutter of this wind-tunnel.
Background technology
Highway, high-speed rail transportation speed of development make rapid progress, and except that automobile, other high-speed rail transportation instrument (as bullet train, magnetic suspension train etc.) also continues to bring out.Like this, lightweight car that the design air kinematic behavior is good and high-speed rail transportation rolling stock, improve the aerodynamic stability of rapid, improve their dynamic property and the inner flowing characteristic of economy and pilothouse, improve the usefulness of engine, brake system, reduce the primary study exploitation content that aerodynamic noise becomes this class automobile and high-speed rail transportation instrument.Vehicle complete vehicle wind tunnel test equipment plays irreplaceable effect in these research work.But still there are many technological difficulties in automobile wind tunnel design and the construction, wherein, low frequency flutter problem directly has influence on the flow quality of test section, influence pneumatic and acoustics (in the acoustic wind tunnel) performance measurement of testpieces, the experimental ability of wind-tunnel is restricted, always be the world-famous puzzle of open-jet wind tunnel research field, also do not have effective solution up to now.
Since the seventies in last century, people recognize that gradually ubiquity low frequency flutter phenomenon in the automobile wind tunnel, promptly in full-scale wind tunnel, several tangible resonance peaks appear in the interior meeting of frequency range that is lower than 20Hz, and the frequency that these peak values occur is relevant with wind speed, the wind speed that peak-peak occurs also is uncertain, the size of its peak value is difficult to prediction especially, thereby the research that how to reduce low frequency flutter amplitude also becomes one of essential scientific research project gradually in the design process of automobile wind tunnel.External wind-tunnel construction experiences shows, if can not effectively suppress low frequency flutter phenomenon, brings not only can for relevant wind tunnel experiment and seriously influence, even might destroy the structure of wind-tunnel itself.Because people are not very clear producing such flutter mechanism, thereby control method miscellaneous occurred, however different control methods stress results for different wind-tunnel and also be not quite similar, its relative merits are respectively arranged.The control technology of low frequency flutter in the past has following several:
1) the spout place adds spoiler: this technology is to arrange the big flakelet of some certain sizes symmetrically on two sides in spout exit and an end face, destroy large-scale eddy current in the wind tunnel spout place shear layer with this, thereby reach the effect that suppresses low-frequency noise;
2) flow-disturbing groove: this technology is to collect the different groove of epistome layout, makes air-flow arrival can be scatter when collecting mouth, collects mouth and the aerodynamic noise of generation thereby reduce airflow collision;
3) opening angle of change collection mouth, thus spout and the area ratio change of collecting mouth made;
4) in having covered the test bypass line of resilient material, process hole, thereby change the acoustics mode of this bypass line, its resonant frequency is improved;
5) adopt the control technology (for example wind-tunnel of AUDI motor corporation) that initiatively resonates, suppress acoustic resonance in the wind-tunnel loop by the use speaker system;
6) make in the chamber and communicate, change the acoustics mode of staying the chamber with atmosphere.
These control methods all have the limitation of himself.The method that adds spoiler as the spout place is easy to generate the noise of high frequency; Layout groove or change collection mouthful opening angle need repeatedly be tested repeatedly and be made amendment before collecting mouth, and very consuming time; The method of utilizing loudspeaker that Adui company is adopted is the cost costliness then, needs strict control flow table just can get a desired effect simultaneously, or the like.Common shortcoming be with strong points, versatility is poor, and it is different because of different wind-tunnel to reduce the effect of low frequency flutter.
So the present technology that also needs the new inhibition low frequency flutter of continuous experimental study makes automobile wind tunnel obtain good experiment measuring environment.
Summary of the invention
Pneumatic-acoustic wind tunnel structure that the technical problem to be solved in the present invention provides a kind of open closed formula that can effectively suppress wind-tunnel medium and low frequency flutter phenomenon.
In order to solve the problems of the technologies described above, the present invention adopts following technical scheme: the low frequency structure for restraining flutter of the pneumatic acoustic wind tunnel of a kind of open closed formula, described wind-tunnel is successively by blower fan, the blower fan diffuser, the 3rd turning, heat interchanger, the 4th turning, honeycomb, damping screen, contraction section, spout, jet segment, collect mouth, diffuser, first turning, first transition section, second turning and blower fan wind inlet section are formed, spout wherein, jet segment and collection mouth all are contained in wind-tunnel and stay indoor, at a diffuser that links to each other with the collection mouth, first turning, the top at first transition section and second turning is provided with cavity structure, and described cavity structure is provided with a plurality of air vents and wind-tunnel runner, staying the chamber communicates.
Preferably, described cavity structure is positioned at the top of collecting mouth with the air vent that communicates in the chamber.
Preferably, the air vent that communicates with the wind-tunnel runner of described cavity structure is positioned at the top of diffuser and the top at second turning.
Preferably, the adjustable size of described air vent.
The present invention stays the inducement of indoor generation low frequency flutter phenomenon from research, add and stay the cavity structure that chamber and runner communicate, absorbed the low frequency flutter energy under the resonant frequency, also changed ducted resonance acoustic mode attitude, changed and stayed indoor Flow Field Distribution, and then changed the feedback mechanism of collecting mouthful, thus reduced the low frequency flutter, improve the experimental measurement environment of test section flow field and sound field.
Description of drawings
Below in conjunction with the drawings and specific embodiments the present invention is described in further detail.
Fig. 1 is the vertical view (analysing and observe) of original construction of wind tunnel.
Fig. 2 is the front view of original construction of wind tunnel.
Fig. 3 is the right view of original construction of wind tunnel.
Fig. 4 is the vertical view (analysing and observe) of construction of wind tunnel of the present invention.
Fig. 5 is the front view of construction of wind tunnel of the present invention.
Fig. 6 is the right view of construction of wind tunnel of the present invention.
Fig. 7 is the situation of change of original structure different wind speed downforce ripple factors at standard measuring point place.
Fig. 8 is the pressure fluctuation coefficient figure after the employing structure of the present invention.
Fig. 9 is the another kind of pressure fluctuation coefficient figure after the employing structure of the present invention.
Among the figure: 1 is spout, 2 is jet segment, and 3 for collecting mouth, and 4 is diffuser, 5 is first turning, 6 is first transition section, and 7 is second turning, and 8 for staying the chamber, 9,10,12 is air vent, 11 is that three different frequency sections have been represented in cavity structure, cp range1～3, and cp OA represents a broad frequency band, the maximal value in the cp peak max broad frequency band.
Embodiment
Along the direction of following current, open closed formula low-speed wind tunnel is made up of blower fan, blower fan diffuser, the 3rd turning, heat interchanger, the 4th turning, honeycomb, damping screen, contraction section, spout, jet segment, collection mouth, diffuser, first turning, first transition section, second turning and blower fan wind inlet section successively.Fig. 1, Fig. 2 and Fig. 3 show wherein one section, and wherein spout 1, jet segment 2 and collection mouth 3 all are contained in wind-tunnel in chamber 8, and diffuser 4, first turning 5, first transition section 6 and second turning 7 have constituted one section runner of wind-tunnel.
Structure of the present invention such as Fig. 4, Fig. 5 and shown in Figure 6, with collect mouthful 3 diffusers that link to each other 4, first turning 5, first transition section 6 and second turning 7 above increased a cavity structure 11, above collection mouth 3, be provided with an air vent 12, make cavity structure 11 and communicate in chamber 8, be provided with an air vent 9 at the top of diffuser 4 and communicate, be provided with an air vent 10 at the top at second turning 7 and communicate with cavity structure with cavity structure 11.
The present invention has added and has stayed the cavity structure that chamber and runner communicate, and is suppressing the low frequency flutter, is improving and using aspect acoustic enviroment in the chamber and the flow field quality.Use the present invention to produce different inhibition effects for low frequency flutter amplitude, can pass through calculating pressure ripple factor Cp, peak weighs the effect that reduces the low frequency flutter, and computing method are as follows:
Cp, peak---pressure fluctuation coefficient in peak value place under a certain frequency band;
p
Dyn---the measuring point dynamic pressure;
p
0---reference pressure (20 μ Pa)
Lp, peak---peak value place sound pressure level under a certain frequency band.
Compare experiment with original structure and structure of the present invention, by drawing pressure fluctuation coefficient figure structure of the present invention as can be seen in the effect aspect the flutter of inhibition low frequency.
Experiment 2: adopt construction of wind tunnel of the present invention, collect mouthful fair water fin corner 0 degree, throat is seamless, the first diffuser The initial segment is seamless, spout top aperture area is area of injection orifice 25%, collect a mouthful top aperture area is 30% of area of injection orifice, the air vent at diffuser top opens 1/3.By the experiment measuring of different wind speed, the pressure fluctuation coefficient as shown in Figure 9, as can be seen, its maximum pressure fluctuation coefficient is 1.5%.Compare (about 7%) with the low frequency flutter maximum amplitude of original structure, decreased by 78.6%.
From result of experiment, the present invention has obtained good effect, the maximum range of decrease of low frequency flutter amplitude of place, axis in chamber standard measuring point can reach 78.6%, the flutter peak value that occurs at different wind speed sections particularly, can connect cavity by different air vents and different perforated areas controls, these all help carrying out in the wind-tunnel aerodynamics and noise analysis experiment, thereby obtain believable experimental data.
Claims (4)
- An open closed formula pneumatic-the low frequency structure for restraining flutter of acoustic wind tunnel, described wind-tunnel is successively by blower fan, the blower fan diffuser, the 3rd turning, heat interchanger, the 4th turning, honeycomb, damping screen, contraction section, spout, jet segment, collect mouth, diffuser, first turning, first transition section, second turning and blower fan wind inlet section are formed, spout wherein, jet segment and collection mouth all are contained in wind-tunnel and stay indoor, it is characterized in that: at a diffuser that links to each other with the collection mouth, first turning, the top at first transition section and second turning is provided with cavity structure, described cavity structure is provided with a plurality of air vents, wherein the part air vent communicates with the wind-tunnel runner, the part air vent with stay the chamber and communicate.
- 2. open closed formula according to claim 1 is pneumatic-the low frequency structure for restraining flutter of acoustic wind tunnel, it is characterized in that: described cavity structure with stay air vent that the chamber communicates and be positioned at the top of collecting mouthful.
- 3. open closed formula according to claim 1 is pneumatic-the low frequency structure for restraining flutter of acoustic wind tunnel, and it is characterized in that: the air vent that described cavity structure communicates with the wind-tunnel runner is positioned at the top of diffuser and the top at second turning.
- According to claim 1,2 or 3 described open closed formulas pneumatic-the low frequency structure for restraining flutter of acoustic wind tunnel, it is characterized in that: the adjustable size of described air vent.
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| CNB2007100938642A CN100559144C (en) | 2007-06-14 | 2007-06-14 | Open closed formula is pneumatic-the low frequency structure for restraining flutter of acoustic wind tunnel |
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| CNB2007100938642A CN100559144C (en) | 2007-06-14 | 2007-06-14 | Open closed formula is pneumatic-the low frequency structure for restraining flutter of acoustic wind tunnel |
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| CN100559144C true CN100559144C (en) | 2009-11-11 |
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Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101696695B (en) * | 2009-10-23 | 2011-11-23 | 上海鼓风机厂有限公司 | Axial flow compressor serially connected by multiple single-stage axial flow fans in L-shaped arrangement |
| RU2547473C1 (en) * | 2013-12-12 | 2015-04-10 | Федеральное государственное унитарное предприятие "Центральный аэрогидродинамический институт имени профессора Н.Е. Жуковского" (ФГУП "ЦАГИ") | Test section of wind tunnel |
| CN106323586B (en) * | 2016-08-02 | 2019-01-18 | 中国航天空气动力技术研究院 | Experimental rig for multi-port lateral jet |
| CN108344555B (en) * | 2018-04-13 | 2019-01-29 | 中国空气动力研究与发展中心低速空气动力研究所 | A kind of anechoic room inhibiting opening jet stream wind-tunnel far field low frequency pulsation |
| CN113494988B (en) * | 2020-03-20 | 2023-06-23 | 上海汽轮机厂有限公司 | Ventilation system and application thereof |
| CN111929026B (en) * | 2020-09-29 | 2020-12-15 | 中国空气动力研究与发展中心低速空气动力研究所 | Low-frequency pressure pulsation suppression method for wind tunnel 3/4 opening test section |
| CN112197933B (en) * | 2020-12-10 | 2021-02-26 | 中国空气动力研究与发展中心低速空气动力研究所 | Width-adjustable opening jet flow wind tunnel chamber and opening jet flow wind tunnel test method |
| CN112985746B (en) * | 2021-04-23 | 2021-11-23 | 中国空气动力研究与发展中心低速空气动力研究所 | Opening jet flow wind tunnel collector capable of moving back and forth and adjusting width and test method |
| CN112985749B (en) * | 2021-05-12 | 2021-08-03 | 中国航空工业集团公司沈阳空气动力研究所 | Cavity noise suppression wind tunnel test device based on sound absorption material |
| CN115962911B (en) * | 2023-03-16 | 2023-05-12 | 中国航空工业集团公司沈阳空气动力研究所 | Safe and stable operation control system of cross supersonic wind tunnel and design method |
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Non-Patent Citations (2)
| Title |
|---|
| 一种抑制低频颤振的控制方法在模型风洞中的试验研究. 郑志强等.汽车工程，第29卷第5期. 2007 |
| 一种抑制低频颤振的控制方法在模型风洞中的试验研究. 郑志强等.汽车工程，第29卷第5期. 2007 * |
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