阅读说明：本技术 一种可自动切换的并列式赫姆霍兹共鸣器及其工作方法 (Parallel Helmholtz resonator capable of being automatically switched and working method thereof ) 是由 赵丹 吴维维 潘伟宸 徐啸 陆拯礼 赵鹤 于 2020-12-23 设计创作，主要内容包括：本发明公开了一种可自动切换的并列式赫姆霍兹共鸣器,包括主管道,与主管道连接并用于采集声学信号的控制系统,设置在控制系统一侧与主管道连接并用于消声的消声组件以及设置在消声组件外与控制系统信号连接并用于控制消声组件沿主管道移动的齿轮齿板传动系统；消声组件由若干赫姆霍兹工作器并列设置组成,赫姆霍兹工作器包括共振腔以及与用于与主管道连接的颈部,主管道上设置有与颈部对应连接的消声孔；赫姆霍兹工作器的共振腔内设有用于调节阻尼频率的刚性挡板。本发明通过齿轮的转动从而移动并列式赫姆霍兹共鸣器,不但大幅提高了消声效果,产生了多个传递损失峰值,而且扩充了可以用于消声的工作频率范围,以达到最优的消声效果。(The invention discloses a parallel Helmholtz resonator capable of automatically switching, which comprises a main pipeline, a control system, a silencing assembly and a toothed plate transmission system, wherein the control system is connected with the main pipeline and is used for collecting acoustic signals; the noise elimination assembly is formed by arranging a plurality of Helmholtz working devices in parallel, each Helmholtz working device comprises a resonant cavity and a neck part used for being connected with the main pipeline, and the main pipeline is provided with noise elimination holes correspondingly connected with the neck parts; a rigid baffle for adjusting the damping frequency is arranged in the resonant cavity of the Helmholtz working device. The parallel Helmholtz resonators are moved through the rotation of the gears, so that the noise elimination effect is greatly improved, a plurality of transmission loss peak values are generated, and the working frequency range which can be used for noise elimination is expanded to achieve the optimal noise elimination effect.)

1. The utility model provides a but parallel helmholtz resonator of automatic switch-over, includes trunk line (1), its characterized in that: the noise-abatement device also comprises a control system which is connected with the main pipeline (1) and is used for collecting acoustic signals, a noise-abatement component which is arranged on one side of the control system and is connected with the main pipeline (1) and is used for abating noise, and a gear toothed plate transmission system which is arranged outside the noise-abatement component and is in signal connection with the control system and is used for controlling the noise-abatement component to move along the main pipeline (1); the noise elimination assembly is formed by arranging a plurality of Helmholtz working devices (11) in parallel, each Helmholtz working device (11) comprises a resonant cavity (111) and a neck (112) connected with a main pipeline (1), and each main pipeline is provided with a noise elimination hole (101) correspondingly connected with the neck (112); a rigid baffle (113) for adjusting the damping frequency is arranged in the resonant cavity of the Helmholtz working device (11).

2. The automatically switchable parallel helmholtz resonator of claim 1, wherein: the damping frequency increases with the number of rigid baffles (113).

3. The automatically switchable parallel helmholtz resonator of claim 1 or 2, wherein: the rigid baffle (113) is transversely arranged along the resonant cavity (111) and equally divides the resonant cavity (111), a through hole (1131) aligned with the neck (112) is formed in the rigid baffle (113), and the diameter of the through hole (1131) is consistent with that of the neck (112).

4. The automatically switchable parallel helmholtz resonator of claim 1 or 2, wherein: the thickness of the rigid baffle (113) is one third to two thirds of the height of the neck (112).

5. The automatically switchable parallel helmholtz resonator of claim 1, wherein: the gear and toothed plate transmission system comprises a gear rotating shaft rod (8), a gear (7), a toothed plate (9) and a moving clamping groove (10), the moving clamping groove (10) is fixed on the outer surface of the main pipeline (1), the toothed plate (9) is arranged in the moving clamping groove (10), one end of the toothed plate (9) is fixedly connected with the neck (112) of the Helmholtz working device, the gear rotating shaft rod (8) is arranged on one side of the toothed plate (9), the end of the gear rotating shaft rod (8) is provided with the gear (7), and the gear (7) is meshed with toothed plate teeth (901) on the toothed plate (9).

6. The automatically switchable parallel helmholtz resonator of claim 5, wherein: the control system comprises an acoustic sensor (2), a signal processor (4), a stepping motor controller (5) and a stepping motor (6); the acoustic sensor (2) is embedded into the inner wall of the main pipeline (1), and the signal output end of the acoustic sensor (2) is connected with the signal input end of the signal processor (4); the signal output end of the signal processor (4) is connected with the signal input end of the stepping motor controller (5); the signal output end of the stepping motor controller (5) is connected with the signal input end of the stepping motor (6), and the signal output end of the stepping motor (6) is connected with the gear rotating shaft rod (8).

7. The automatically switchable parallel helmholtz resonator of claim 6, wherein: and a sealing ring (3) for sealing and fixing is arranged at the position where the acoustic sensor (2) is connected with the main pipeline (1).

8. A method of operating an automatically switchable parallel helmholtz resonator as claimed in claim 1, comprising the steps of:

step one, an acoustic sensor (2) collects the tangential flow velocity in a main pipeline (1) to form an acoustic signal, and sends the acoustic signal to a signal processor (4);

step two, the signal processor (4) converts the acoustic signals into electric signals and sends the electric signals to the stepping motor controller (5);

step three, the stepping motor controller (5) controls the stepping motor (6) to rotate according to the electric signal, the stepping motor (6) drives the gear (7) to rotate through the gear shaft lever (8), the gear (7) and the toothed plate teeth of the toothed plate (9) act to drive the toothed plate (9) to move, and the noise is eliminated according to different damping frequencies by changing the relative positions of the noise elimination assembly and the main pipeline.

9. The method of operating an automatically switchable parallel helmholtz resonator as set forth in claim 8, wherein: in the third step, the damping frequency range is 0-500 Hz.

Technical Field

The invention relates to a common silencer, in particular to a parallel Helmholtz resonator capable of being automatically switched and a working method thereof.

Background

The traditional helmholtz resonance is widely used in aircraft engines and gas turbines as a noise damping device. The neck of Helmholtz resonator is equivalent to a base, and the air of sympathetic response intracavity is equivalent to a spring, and the resonance takes place when the air sound wave of sympathetic response intracavity is unanimous with the frequency of resonator to reach the biggest noise elimination effect. In addition, the vibration friction of air on the wall surface of the opening can cause acoustic energy loss due to viscous damping and heat conduction, and the acoustic effect of the air is acoustic resistance. However, there are fewer individual helmholtz resonator peaks and a lower resonance frequency. Therefore, in order to widen the damping frequency range, the helmholtz resonator needs to be switched according to different practical situations, so as to achieve an ideal noise elimination effect.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a parallel Helmholtz resonator which has a plurality of resonance peaks and wide damping frequency; a second object of the present invention is to provide a method of operating the helmholtz resonator.

The technical scheme is as follows: the invention relates to an automatically-switched parallel Helmholtz resonator, which comprises a main pipeline, a control system, a silencing assembly and a toothed plate transmission system, wherein the control system is connected with the main pipeline and is used for collecting acoustic signals; the noise elimination assembly is formed by arranging a plurality of Helmholtz working devices in parallel, each Helmholtz working device comprises a resonant cavity and a neck part used for being connected with a main pipeline, and the main pipeline is provided with noise elimination holes correspondingly connected with the neck parts; a rigid baffle plate for adjusting damping frequency is arranged in the resonant cavity of the Helmholtz working device.

The damping frequency increases with the number of rigid baffles. The rigid baffle is transversely arranged in the resonant cavity and equally divides the resonant cavity, and the equal division aims to increase the number of Helmholtz working devices, so that the noise elimination performance is improved; the rigid baffle is provided with a through hole aligned with the neck, the diameter of the through hole is consistent with that of the neck, the consistent diameter can ensure that tangential flow in the main pipeline still keeps an initial motion state after entering the resonant cavity, and test errors caused by external environment changes are reduced. The thickness of the rigid baffle is one third to two thirds, preferably one half of the height of the neck, and the thicker rigid baffle can be adopted to regulate and control the internal volume of the resonant cavity.

Foretell pinion rack transmission system includes gear rotating shaft pole, gear, pinion rack and moving clamping groove, moving clamping groove fix at the trunk line surface, the pinion rack arrange moving clamping groove in, the one end of pinion rack and the neck fixed connection of helmholtz worker, one side of pinion rack is equipped with the gear rotating shaft pole, gear rotating shaft pole tip be equipped with the gear, pinion rack tooth intermeshing on gear and the pinion rack.

The control system comprises an acoustic sensor, a signal processor, a stepping motor controller and a stepping motor; the acoustic sensor is embedded in the inner wall of the main pipeline, and the signal output end of the acoustic sensor is connected with the signal input end of the signal processor; the signal output end of the signal processor is connected with the signal input end of the stepping motor controller; the signal output end of the stepping motor controller is connected with the signal input end of the stepping motor, and the signal output end of the stepping motor is connected with the gear rotating shaft rod.

And a sealing ring for sealing and fixing is arranged at the position where the acoustic sensor is connected with the main pipeline.

The invention also provides a working method of the parallel Helmholtz resonator capable of automatically switching, which comprises the following steps:

step one, an acoustic sensor collects the tangential flow velocity in a main pipeline to form an acoustic signal, and sends the acoustic signal to a signal processor;

secondly, the signal processor converts the acoustic signals into electric signals and sends the electric signals to the stepping motor controller;

and step three, the step motor controller controls the step motor to rotate according to the electric signal, the step motor drives the gear to rotate through the gear shaft lever, the gear and the toothed plate of the toothed plate act to drive the toothed plate to move, and the noise is eliminated according to different damping frequencies by changing the relative position of the noise elimination assembly and the main pipeline.

Furthermore, in the third step, the damping frequency range is 0-500 Hz.

Further, in the third step, a specific method for controlling the stepping motor to rotate by the stepping motor controller according to the electric signal is as follows: if the current electric signal is larger than the previous electric signal, the stepping motor controller controls the stepping motor to rotate forwards according to the change of the electric signal; otherwise, the process is reversed.

Further, in the second step, the signal processor converts the acoustic signal into an electrical signal, and the detailed steps are as follows: firstly, carrying out Fourier transform on the acoustic signal obtained in the first step to form a frequency domain signal; then, the main noise frequency is extracted from the frequency domain signal, so that the required electric signal is formed.

The working principle is as follows: the damping frequency formula of the helmholtz working machine is as follows:where c is the speed of sound, V is the volume of the resonant cavity, L_effIs the effective length of the neck, and S is the cross-sectional area of the neck. According to the formula, the factors affecting the damping frequency include the volume of the resonant cavity, the effective length and cross-sectional area of the neck, and the like, and different resonant frequencies correspond to different transmission losses. In the invention, a plurality of Helmholtz workers are arranged in parallel, different Helmholtz workers can be selected for silencing according to the actual noise environment under the control of a gear transmission system, the internal volume of a resonant cavity is divided again by a rigid baffle arranged in the Helmholtz workers, an expansion cavity which can generate transmission loss in cooperation with the resonant cavity is formed, and the transmission loss of the expansion cavity is as follows:wherein, m is the expansion ratio, and S is the cavity cross-sectional area, and k is the constant coefficient, and l is the height of cavity, and the transmission loss of solitary Helmholtz resonator is whole from the resonant cavity, and the transmission loss of the Helmholtz resonator of the baffle of trompil in the middle of the area is except coming from Helmholtz resonator itself, still includes because the resonant cavity has added the extra transmission loss that the expansion chamber that the baffle formed brought, consequently can produce a plurality of formants in order to widen the noise elimination frequency band, increase noise cancelling effect. And along with the increase of the number of the rigid baffles, the volume change in the resonant cavity is large, different transmission loss peak values are also changed continuously, and the adjusted damping frequency can be further improved.

Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: the signal processor is used for collecting and processing the acoustic signals to convert the acoustic signals into electric signals, and the stepping motor controller receives the electric signals, so that the forward and reverse rotation of the stepping motor is adjusted to switch the plurality of Helmholtz resonators arranged in parallel, and the required resonance frequency is achieved. The parallel Helmholtz resonators are moved through the rotation of the gears, so that the noise elimination effect is greatly improved, a plurality of transmission loss peak values are generated, and the working frequency range which can be used for noise elimination is expanded to achieve the optimal noise elimination effect.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a partial view of the seal mounting location of the speed sensor of the present invention;

FIG. 3 is an enlarged view of a portion of the gear system mounting location of the present invention;

FIG. 4 is a schematic structural view of the gear system of the present invention;

fig. 5 is a graph showing a comparison of resonance frequencies corresponding to transmission loss peaks of resonators at different mach numbers in the embodiment of the present invention;

FIG. 6 is a graph showing a comparison of transmission loss of the acoustic resonator at Mach number 0;

FIG. 7 is a graph showing a comparison of transmission loss of the acoustic resonator at Mach number 0.03;

FIG. 8 is a graph showing a comparison of transmission loss of the acoustic resonator at a Mach number of 0.07;

fig. 9 is a comparison of transmission loss peaks at different mach numbers for resonators according to embodiments of the invention.

Detailed Description

The invention is further illustrated by the following figures and examples.

Referring to fig. 1-4, an automatically switchable parallel helmholtz resonator includes a main pipe 1, a control system, a muffler assembly and a toothed plate gear system. A tangent flow is introduced into the main pipeline 1, a control system is installed on the main pipeline 1, the control system comprises an acoustic sensor 2, a signal processor 4, a stepping motor controller 5 and a stepping motor 6, the acoustic sensor 2 adopts Shanghai Muxi PM8 model and is embedded into the inner wall of the main pipeline, and a sealing ring 3 is arranged on the side of the acoustic sensor for fixing and used as the input end of the control system; the acoustic sensor 2 is in signal connection with a signal processor 4, a stepping motor controller 5 and a stepping motor 6 in sequence, the signal processor 4 adopts a Beijing Square control SK2018 model, the stepping motor controller 5 adopts a Leqing DM556 model controller, and the stepping motor 6 adopts a Leqing 86 model stepping motor.

Be equipped with a hole 101 of silencing on trunk line 1, be equipped with the noise elimination subassembly on hole 101 of silencing, this noise elimination subassembly comprises the consistent helmholtz worker 11 of three shape and sets up side by side, the outer wall of adjacent helmholtz worker 11 is laminated fixedly each other, every helmholtz worker 11 includes a cylindric resonance chamber 111 and the neck 112 of being connected with trunk line 1, resonance chamber 111 is cylindrical structure, resonance chamber 111's whole height is 24.42cm, neck 112's whole height is 8.05cm, height and sectional area are all unchangeable, neck 112 is connected with hole 101 of silencing, hole 101 of silencing can also set up a plurality ofly according to actual helmholtz worker 11, thereby can communicate with a plurality of helmholtz workers 11, and then can improve the effect of silencing. In this embodiment, three helmholtz working devices 11 are arranged from left to right, one rigid baffle 113 is arranged in the resonance cavity 111 of the left helmholtz working device 11 at the waist position, no rigid baffle 113 is arranged in the resonance cavity 111 of the middle helmholtz working device 11, two rigid baffles 113 are arranged in the resonance cavity 111 of the right helmholtz working device 11 at one-third height and two-thirds height respectively, the rigid baffles 113 are transversely arranged in the resonance cavity 111, a through hole 1131 aligned with the neck 112 is arranged on the rigid baffle 113, the diameter of the through hole 1131 is identical to the diameter of the neck 112, and the thickness of the rigid baffle 113 is half of the neck, that is, 4.025 cm.

A toothed wheel toothed plate transmission system used for controlling the noise elimination assembly to move along the main pipeline 1 is arranged outside the noise elimination assembly, the toothed wheel toothed plate transmission system comprises a gear rotating shaft rod 8, a gear 7, a toothed plate 9 and a moving clamping groove 10, the moving clamping groove 10 is fixed on the outer surface of the main pipeline 1 and is wholly parallel to the main pipeline 1, the toothed plate 9 is arranged in the moving clamping groove 10, one end of the toothed plate 9 is fixedly connected with the necks 112 of the three Helmholtz working devices respectively, the gear rotating shaft rod 8 is arranged on one side of the toothed plate 9, the gear 7 is arranged at the end part of the gear rotating shaft rod 8, the gear 7 is meshed with toothed plates 901 on the toothed plate 9, the gear rotating shaft rod 8 is in signal connection with a stepping motor 6 and rotates under the control of the stepping motor 6, the gear 7 is further driven to rotate, the gear 7 is meshed with the toothed plate 9, and therefore the, because pinion rack 9 and helmholtz worker's neck 112 fixed connection, consequently can drive holistic noise elimination subassembly and remove on the surface of trunk line 1 to helmholtz worker 11 that can select the difference is connected with the trunk line.

When tangential flow noise gets into trunk line 1, the velocity sensor 2 that is in trunk line 1 upper reaches is to tangential flow noise acoustic signal sampling, acoustic sensor 2 gives signal amplifier with sampled signal transmission, signal amplifier amplifies sampled signal, the signal after the amplification passes through AD converter and converts the acoustic signal of amplifying into the distinguishable signal of signal processor 6, signal processor 6 carries out the analysis to the signal of telecommunication, calculate and draw the noise frequency size, thereby control step motor 6 through step motor controller 5 and control the rotation that gear shaft pole 8, and then control gear 7's rotation, the gear is through the removal that comes the drive pinion rack with pinion rack tooth 901 effect. As can be seen from the comsol5.4 simulation, the noise reduction amount and the noise reduction frequency band of the three parallel helmholtz resonators are much larger than those of the conventional single helmholtz resonator, and referring to fig. 5 to 8, the noise reduction effect when switching to the helmholtz resonator with the single partition and the helmholtz resonator with the double partition is much better than that of the helmholtz resonator without the partition, and especially, the helmholtz resonator with the single partition and the double partition has the best noise reduction effect. However, when the mach number is less than 0.03, the acoustic suppression effects of the helmholtz resonators having three different resonance cavity structures are almost the same in the frequency range of 10 to 200Hz, but when the mach number is more than 0.03, the acoustic suppression effect of the helmholtz resonator having no baffle in the resonance cavity is relatively poor in the frequency range of 10 to 200 Hz. In addition, with the increase of the baffles, the silencing frequency band is continuously expanded and a plurality of resonance peaks are generated, and the selection of the frequency modulation range is more, wherein the sound absorber with one rigid baffle on the left can be selected to be silenced at 200hz and 300hz, the sound absorber without the rigid baffle in the middle can be selected to be silenced at 0-200 hz, and the sound absorbers with two rigid baffles on the right can be selected to be silenced at 400-500 hz. Referring to fig. 8, it can be seen that helmholtz resonance with two baffles on the right has more resonance peaks and the sum of the transmission loss peaks is the highest, and in addition, the muffling channel is greatly expanded.