CN212874037U - Double-layer honeycomb-micro-perforated structure with adjustable back cavity height - Google Patents
Double-layer honeycomb-micro-perforated structure with adjustable back cavity height Download PDFInfo
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- CN212874037U CN212874037U CN202021611681.2U CN202021611681U CN212874037U CN 212874037 U CN212874037 U CN 212874037U CN 202021611681 U CN202021611681 U CN 202021611681U CN 212874037 U CN212874037 U CN 212874037U
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Abstract
The utility model relates to a double-deck honeycomb-microperforated structure of adjustable back of body cavity height, top panel, lower panel, the honeycomb core of clamp between top panel and lower panel, a serial communication port, the top panel is the microperforated panel, be equipped with height-adjustable microperforated panel in the honeycomb core, be equipped with the regulation boss on the microperforated panel, be equipped with adjusting screw in the honeycomb core, be equipped with the external screw thread and the internal thread of mutually supporting in adjusting screw and the regulation boss, adjusting screw's one end is passed panel and this end are provided with down and are used for control adjusting screw's adjust knob changes the distance between top panel and the microperforated panel through rotatory adjust knob to change structural resonance frequency, absorb the noise of different frequencies. The utility model discloses a change the height that contains the microperforated panel in the honeycomb core to the realization structure is to the absorption of different frequency noises, has also improved the application of honeycomb-microperforated panel in making an uproar when having improved the sound absorption effect.
Description
Technical Field
The utility model belongs to a middle and low frequency and broadband noise reduction structure and method which utilizes the honeycomb-micro perforated plate composite structure design, in particular to a double-layer honeycomb-micro perforated structure with adjustable back cavity height and a design method thereof.
Background
The sound absorption structure of the micro-perforated plate is developed on the basis of a common perforated plate structure, and is mainly characterized in that the diameter of a perforated hole is reduced to be less than millimeters, and the relative sound resistivity of the sound absorption structure is controlled by using the sound resistance of the perforated hole, so that a sound absorption material behind the perforated plate can be cancelled, and the sound absorption structure is greatly simplified. The honeycomb sandwich structure has the characteristics of high specific strength, large specific rigidity, good fatigue resistance, flat and smooth surface and the like, is widely used in the field of aviation and the like, and the honeycomb-micro perforated plate structure combining the honeycomb sandwich structure and the micro perforated plate structure has excellent mechanical property and good sound absorption effect.
The sound absorption coefficient of the single-layer micro-perforated plate sound absorption structure is low except a sound absorption peak value, the effective sound absorption frequency band is narrow, the requirement of practical application cannot be well met sometimes, the double-layer micro-perforated plate sound absorption structure can be regarded as two mutually-coupled resonance sound absorption structures, and the double-layer micro-perforated plate sound absorption structure can be used for obtaining higher sound absorption coefficient and wider sound absorption frequency band.
According to the sound absorption principle of the micro-perforated plate, the depth of the plate thickness cavity of the micro-perforated plate structure directly influences the sound absorption performance of the structure, namely the sound absorption frequency and the sound absorption coefficient. In order to improve the sound absorption performance of the structure, one layer of micro-perforated plate of the double-layer honeycomb-micro-perforated structure only keeps vertical up-down freedom and is arranged to be adjustable up and down. Therefore, the height of the board thickness cavity of the micro-perforated board can be changed by changing the position of the layer of micro-perforated board, so that the noise of different frequencies can be absorbed.
SUMMERY OF THE UTILITY MODEL
The utility model discloses to honeycomb-micro-perforated structure sound absorbing structure, designed a double-deck honeycomb-micro-perforated structure of adjustable back of the body chamber height, through the height that contains the microperforated panel in changing the honeycomb core to the realization structure is to the absorption of different frequency noises, has also improved the application of honeycomb-micro-perforated structure in making an uproar when having improved the sound absorption effect.
The utility model discloses a following technical scheme realizes.
A double-layer honeycomb-micro-perforated structure with adjustable back cavity height comprises an upper panel, a lower panel and a honeycomb core clamped between the upper panel and the lower panel, and is characterized in that the upper panel is a micro-perforated panel, a micro-perforated plate with adjustable height is arranged in the honeycomb core, an adjusting boss is arranged on the micro-perforated plate, an adjusting screw is arranged in the honeycomb core, external threads and internal threads which are matched with each other are arranged in the adjusting screw and the adjusting boss, one end of the adjusting screw penetrates through the lower panel, an adjusting knob used for controlling the adjusting screw is arranged at the end of the adjusting screw, a raised line is arranged on the inner wall of the honeycomb core, a groove matched with the raised line is arranged on the outer side of the micro-perforated plate, the raised line is parallel to the axis of the honeycomb core, the distance between the upper panel and the micro-perforated plate is changed by rotating the adjusting knob, absorbing noise at different frequencies.
Preferably, the honeycomb core is arranged in a close-packed circle.
Preferably, the bottom of the adjusting screw penetrates through the lower panel, the bottom of the adjusting screw is in clearance fit with the lower panel to form a self-locking structure, and the middle of the self-locking structure is narrow and the two ends of the self-locking structure are wide.
Preferably, the thread of the adjusting screw is a right-hand rectangular thread.
Preferably, a dial is arranged on the adjusting knob.
A design method of a double-layer honeycomb-micro-perforated structure with adjustable back cavity height is characterized by comprising the following steps:
firstly, verifying the influence of the change of the cavity height on the sound absorption effect of the micro-perforation according to the theory of the micro-perforation plate of the university of Ma 29495 and computer simulation, wherein the sound absorption coefficient when sound waves vertically enter is as follows:
the sound absorption coefficient of the micro-perforated sound absorber reaches the maximum value when the micro-perforated sound absorber resonates, and the maximum sound absorption coefficient value is as follows:
resonant frequency f0Satisfies the following conditions:
2πf0m-cot(2πf0D/c)＝0 (3)
wherein the respective acoustic resistance r and acoustic mass m are:
in the above formulas, k is a perforated plate constant
Mu is kinematic viscosity coefficient of air (1.48X 10)-5m2T is the plate thickness, D is the perforation diameter, D is the cavity height, p is the perforation rate, f is the acoustic frequency, the acoustic resistivity of the cavity behind the plate is
ZD＝-jρccot(ωD/c) (7)
Two-layer microperforated panel m with double-layer microperforated sound absorber1，r1And m2，r2With rear cavities each being D1And D2The relative acoustic impedance of the double-layer series structure can be obtained according to the equivalent circuit
From the above theoretical formulaIt can be known that the resistance of the double-layer microperforated plate is controlled by the parameters of the microperforated plate and the height D of the cavity1、D2Assuming that the microperforated panel parameters are determined, D1And D2The resistance value of the structure is directly influenced, namely, the sound absorption performance of the micro-perforated plate structure can be adjusted by changing the cavity height D of the micro-perforated plate.
Second, based on the above impedance value with the cavity height D1And D2The change rule of (2) designs a double-layer honeycomb-micro-perforated structure with adjustable back cavity height, the structure adopts a densely-arranged circular honeycomb core, and the purpose of changing the acoustic impedance of the cavity behind the plate is achieved by changing the position of a micro-perforated plate in the honeycomb core, so that the absorption of noise with different frequencies is realized.
Compared with the prior art, the utility model has the advantages that:
1. the double-layer honeycomb-micro-perforated structure can realize the best absorption of noise by changing the resonant frequency of the structure by changing the height of the back cavity aiming at the noise with different frequencies;
2. compared with a single-layer honeycomb-micro-perforated structure, the double-layer honeycomb-micro-perforated structure of the utility model has better sound absorption effect;
3. the double-layer honeycomb-micro-perforation structure has simple manufacture and simple operation, and has wide application prospect in the noise reduction field.
Drawings
FIG. 1 is a conventional close-packed circular honeycomb-microperforated structure;
fig. 2 is a schematic diagram of a honeycomb core cell structure according to the present invention;
fig. 3 is a schematic diagram of the internal structure of a honeycomb core cell according to the present invention;
fig. 4 is a schematic view of the self-locking structure of the utility model:
FIG. 5 is a top view of a honeycomb core side wall of the present invention;
FIG. 6 is a top view of the inner microperforated panel of the present invention;
FIG. 7 is a schematic view of the boss of the present invention;
FIG. 8 is a schematic view of the screw structure of the present invention;
FIG. 9 is a schematic view of the knob structure for controlling the rotation of the screw rod according to the present invention;
FIG. 10 is a honeycomb-microperforated structure of modified adjustable back cavity height;
FIG. 11 is a graph of sound absorption effect of an embodiment;
in the figure: 1. the honeycomb core comprises an upper panel, 2, a honeycomb core, 3, a lower panel, 4, a screw, 5, a micro-perforated plate, 6, a boss, 7, a knob, 8, a convex strip, 9 and a groove.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific embodiments, but the present invention is not limited thereto.
As shown in fig. 1, a common densely-arranged circular honeycomb-micro-perforated plate is composed of an upper panel 1, a densely-arranged circular honeycomb core 2 and a lower panel 3, wherein the upper panel is a micro-perforated plate with a certain perforation rate, the honeycomb core is in a densely-arranged circular structure, and the lower panel is a common metal sheet.
The utility model discloses improve ordinary honeycomb core sandwich structure, set honeycomb core structure to the structure that contains screw rod and microperforated panel.
As shown in fig. 2 to 10, a double-layer honeycomb-micro-perforated structure with adjustable back cavity height, an upper panel 1, a lower panel 3, and a honeycomb core 2 sandwiched between the upper panel 1 and the lower panel 3, wherein the upper panel 1 is a micro-perforated panel, a micro-perforated plate 5 with adjustable height is arranged in the honeycomb core 2, an adjusting boss 6 is arranged on the micro-perforated plate 5, an adjusting screw 4 is arranged in the honeycomb core 2, external threads and internal threads which are mutually matched are arranged in the adjusting screw 4 and the adjusting boss 6, one end of the adjusting screw 4 passes through the lower panel 3 and is provided with an adjusting knob 7 for controlling the adjusting screw 4, a raised strip 8 is arranged on the inner wall of the honeycomb core 2, a groove 9 matched with the raised strip 8 is arranged on the outer side of the micro-perforated plate 5, and the raised strip 8 is parallel to the axis of the honeycomb core 2, the distance between the upper panel 1 and the micro-perforated plate 5 is changed by rotating the adjusting knob 7, so that the structural resonance frequency is changed, and noises with different frequencies are absorbed. The ridges 8 and grooves 9 limit the degree of freedom of the microperforated plate 5 so that the microperforated plate 5 can only move up and down along the screw and cannot rotate with the screw.
In a preferred embodiment, the honeycomb core 2 is arranged in a close-packed circular arrangement.
As a preferred embodiment, the bottom of the adjusting screw rod 4 penetrates through the lower panel 3, the bottom of the adjusting screw rod 4 and the lower panel 3 are in clearance fit to form a self-locking structure, and the middle of the self-locking structure is narrow and the two ends of the self-locking structure are wide.
As a preferred embodiment, the thread of the adjusting screw 4 is a right-hand rectangular thread.
In a preferred embodiment, the adjusting knob 7 is provided with a dial.
A single adjustable back cavity height two-layer honeycomb-microperforated structure cell is shown in fig. 2 and 3. Fig. 2 is a schematic structural diagram of a single cell with a double-layer honeycomb-micro-perforated structure and adjustable back cavity height, and the honeycomb core 2 is arranged in a close-packed circular manner. Fig. 3 is a schematic diagram of the internal structure of a cell with a dual-layer honeycomb-micro-perforated structure and adjustable back cavity height. Fig. 4 is the self-locking structure schematic diagram of the utility model, during installation, only need to push the screw rod 4 into the inside self-locking structure that forms of honeycomb core 2, alright guarantee that the screw rod 4 can not fall out. Fig. 5 is the utility model discloses honeycomb core top view, fig. 6 is the utility model discloses inside microperforated panel top view, the recess in the microperforated panel 5 outside cooperatees with the arch of 2 inner walls of honeycomb core in order to restrict the degree of freedom of microperforated panel 5, so that microperforated panel 5 can only reciprocate along the screw rod. Fig. 7 is the utility model discloses the boss schematic diagram, fig. 8 is the utility model discloses the screw rod schematic diagram, the built-in screw hole of 6 of boss of microperforated panel 5 below, screw hole size and 4 screw-thread cooperations of screw rod. Fig. 9 is a schematic diagram of the knob of the present invention, and the ascending height of the microperforated plate 5 inside the honeycomb core can be controlled by the above scale.
A design method of a double-layer honeycomb-micro-perforated structure with adjustable back cavity height is characterized by comprising the following steps:
firstly, verifying the influence of the change of the cavity height on the sound absorption effect of the micro-perforation according to the theory of the micro-perforation plate of the university of Ma 29495 and computer simulation, wherein the sound absorption coefficient when sound waves vertically enter is as follows:
the sound absorption coefficient of the micro-perforated sound absorber reaches the maximum value when the micro-perforated sound absorber resonates, and the maximum sound absorption coefficient value is as follows:
resonant frequency f0Satisfies the following conditions:
2πf0m-cot(2πf0D/c)＝0 (3)
wherein the respective acoustic resistance r and acoustic mass m are:
in the above formulas, k is a perforated plate constant
Mu is kinematic viscosity coefficient of air (1.48X 10)-5m2T is the plate thickness, D is the perforation diameter, D is the cavity height, p is the perforation rate, f is the acoustic frequency, the acoustic resistivity of the cavity behind the plate is
ZD＝-jρccot(ωD/c) (7)
Two-layer microperforated panel m with double-layer microperforated sound absorber1，r1And m2，r2With rear cavities each being D1And D2The relative acoustic impedance of the double-layer series structure can be obtained according to the equivalent circuit
From the above theoretical formula, the resistance of the double-layer micro-perforated plate is determined by the parameters of the micro-perforated plate and the height D of the cavity1、D2Assuming that the microperforated panel parameters are determined, D1And D2The resistance value of the structure is directly influenced, namely, the sound absorption performance of the micro-perforated plate structure can be adjusted by changing the cavity height D of the micro-perforated plate.
Second, based on the above impedance value with the cavity height D1And D2The change rule of (2) designs a double-layer honeycomb-micro-perforated structure with adjustable back cavity height, the structure adopts a densely-arranged circular honeycomb core, and the purpose of changing the acoustic impedance of the cavity behind the plate is achieved by changing the position of a micro-perforated plate in the honeycomb core, so that the absorption of noise with different frequencies is realized.
Example (b):
a single adjustable back cavity height two-layer honeycomb core cell is shown in fig. 3, 4 and 5. Wherein each structure size is as follows: the outer diameter of the honeycomb core 2 is 29mm, the inner diameter is 28mm, and the height is 60 mm; the screw rod 4 is a right-handed rectangular thread with a large diameter of 4mm, a small diameter of 2mm and a thread pitch of 4 mm; the thickness of a micro-perforated plate 1 is 1mm, the aperture is 0.5mm, and the perforation rate is 1%; the microperforated plate 5 had a plate thickness of 1mm, a hole diameter of 0.5mm and a perforation rate of 1%. The microperforated plate 5 has a thickness of only 1mm, and a boss 7 having a height of 5mm and a diameter of 5mm is provided thereunder. The boss 7 is internally provided with a threaded hole, and the size of the threaded hole is matched with the screw rod 4 in a threaded manner. In the present embodiment, the sound absorption coefficients of the three cases, that is, the height of the microperforated panel 5 from the bottom of the honeycomb core is 10mm, the height of the microperforated panel 5 from the bottom of the honeycomb core is 30mm, and the height of the microperforated panel 5 from the bottom of the honeycomb core is 50mm, are calculated, and the structure is set in a cylindrical shape with a diameter of 29mm so as to facilitate measurement in an impedance tube.
FIG. 11 shows the sound absorption effect of the structure in the first case, i.e., the sound absorption coefficient of the structure in which the height of the microperforated panel 5 from the bottom of the honeycomb core is 10mm, and D in this case1And D250mm and 10mm respectively; second caseThe sound absorption coefficient of the structure with the height of the micro-perforated plate 5 being 30mm from the bottom of the honeycomb core, and the structure D at the moment1And D2Are all 30 mm; third case microperforated panel 5 has a sound absorption coefficient of the structure at 50 f from the height of the honeycomb core bottom, when D of the structure1And D210mm and 50mm respectively. According to the figure, the double-layer honeycomb-micro-perforated structure with the height-adjustable back cavity has good absorption effect on noise at low frequency, medium frequency and medium frequency, and the best absorption of the structure on different frequencies is realized by changing the height of the micro-perforated plate inside the honeycomb core from the bottom of the honeycomb core.
The above description is only an example of the preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and those skilled in the art should be able to realize the equivalent alternatives and obvious variations of the present invention.
Claims (5)
1. A double-layer honeycomb-micro perforation structure with adjustable back cavity height comprises an upper panel (1), a lower panel (3) and a honeycomb core (2) clamped between the upper panel (1) and the lower panel (3), and is characterized in that the upper panel (1) is a micro perforation panel, a micro perforation plate (5) with adjustable height is arranged in the honeycomb core (2), an adjusting boss (6) is arranged on the micro perforation plate (5), an adjusting screw rod (4) is arranged in the honeycomb core (2), external threads and internal threads which are matched with each other are arranged in the adjusting screw rod (4) and the adjusting boss (6), one end of the adjusting screw rod (4) penetrates through the lower panel (3) and is provided with an adjusting knob (7) used for controlling the adjusting screw rod (4), a raised strip (8) is arranged on the inner wall of the honeycomb core (2), a groove (9) matched with the raised strip (8) is arranged on the outer side of the micro perforation plate (5), the convex strips (8) are parallel to the axis of the honeycomb core (2), and the distance between the upper panel (1) and the micro-perforated plate (5) is changed by rotating the adjusting knob (7), so that the structural resonance frequency is changed, and noises with different frequencies are absorbed.
2. The double-layered honeycomb-microperforation structure with adjustable back cavity height of claim 1, characterized in that the honeycomb core (2) is in a close-packed circular arrangement.
3. The double-layer honeycomb-micro perforated structure with the adjustable back cavity height of claim 1, characterized in that the bottom of the adjusting screw (4) penetrates through the lower panel (3), the bottom of the adjusting screw (4) and the lower panel (3) are in clearance fit to form a self-locking structure, and the self-locking structure is narrow in the middle and wide at two ends.
4. The double-layered honeycomb-microperforation structure with adjustable back cavity height of claim 1, characterized in that the thread of the adjusting screw (4) is a right-hand rectangular thread.
5. Double-layered honeycomb-microperforation structure with adjustable back cavity height according to claim 1, characterized in that a dial is provided on the adjusting knob (7).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021611681.2U CN212874037U (en) | 2020-08-05 | 2020-08-05 | Double-layer honeycomb-micro-perforated structure with adjustable back cavity height |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202021611681.2U CN212874037U (en) | 2020-08-05 | 2020-08-05 | Double-layer honeycomb-micro-perforated structure with adjustable back cavity height |
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| CN212874037U true CN212874037U (en) | 2021-04-02 |
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| CN202021611681.2U Expired - Fee Related CN212874037U (en) | 2020-08-05 | 2020-08-05 | Double-layer honeycomb-micro-perforated structure with adjustable back cavity height |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111816151A (en) * | 2020-08-05 | 2020-10-23 | 南昌航空大学 | Double-layer honeycomb-micro-perforated structure with adjustable back cavity height and design method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111816151A (en) * | 2020-08-05 | 2020-10-23 | 南昌航空大学 | Double-layer honeycomb-micro-perforated structure with adjustable back cavity height and design method thereof |
| CN111816151B (en) * | 2020-08-05 | 2024-11-08 | 南昌航空大学 | Double-layer honeycomb-microperforation structure with adjustable back cavity height and design method thereof |
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