CN112967708A - Cavity-movable Helmholtz resonator and control method thereof - Google Patents
Cavity-movable Helmholtz resonator and control method thereof Download PDFInfo
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- CN112967708A CN112967708A CN202110135328.4A CN202110135328A CN112967708A CN 112967708 A CN112967708 A CN 112967708A CN 202110135328 A CN202110135328 A CN 202110135328A CN 112967708 A CN112967708 A CN 112967708A
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- 238000000034 method Methods 0.000 title claims abstract description 12
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 6
- 230000005540 biological transmission Effects 0.000 claims description 11
- 238000009304 pastoral farming Methods 0.000 claims description 6
- 239000012530 fluid Substances 0.000 claims description 4
- 230000001743 silencing effect Effects 0.000 claims description 4
- 230000030279 gene silencing Effects 0.000 abstract description 3
- 230000000694 effects Effects 0.000 description 4
- 230000009977 dual effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003584 silencer Effects 0.000 description 1
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/172—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using resonance effects
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/161—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general in systems with fluid flow
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Abstract
The invention discloses a cavity movable type Helmholtz resonator and a control method thereof, wherein the resonator comprises a main air inlet pipeline, a neck short pipe which is vertically arranged with the main air inlet pipeline and is communicated with the main air inlet pipeline is fixedly arranged on the main air inlet pipeline, a rigid back plate is fixedly arranged at the end part of the neck short pipe, a movable cavity component is arranged on the rigid back plate, a resonance cavity which can slide on the movable cavity component is arranged on the movable cavity component, the interior of the resonance cavity is communicated with the neck short pipe, and a system control module is also arranged at the upstream position of the main air inlet pipeline. The invention converts the measured flow velocity signal through a series of signals by the L-shaped pitot tube, transmits the signals to the stepping motor, and drives the double-gear moving guide rod component to move, thereby controlling the offset distance between the resonance cavity and the neck short pipe and achieving the purpose that the Helmholtz resonator always keeps the best silencing performance under different flowing Mach numbers.
Description
Technical Field
The invention relates to a Helmholtz resonator, in particular to a Helmholtz resonator with a movable cavity and a control method thereof.
Background
Helmholtz resonators are widely used in aircraft engines and gas turbines as a typical noise reduction device to reduce the propagation of noise. However, the helmholtz resonator with the asymmetric structure can be designed due to the limited space of the engine, but the traditional helmholtz resonator with the asymmetric structure can only play the maximum sound eliminating effect for a specific flow speed.
The invention patent with application number CN201910966633.0 entitled helmholtz resonator and its working method discloses a structure of two coupled resonant cavities, between which the aperture size is adjusted by diaphragm valve. The device well widens the silencing frequency band of the silencer and increases the number of resonance peaks; however, when the flow mach number changes in the main intake pipe, the muffling effect becomes significantly weak. Therefore, how to always maximize the noise reduction effect of the helmholtz resonator when the flow mach number is changed becomes a problem in designing the helmholtz resonator.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a cavity movable type Helmholtz resonator and a control method thereof, and solves the problem that the traditional Helmholtz resonator has weak noise reduction under the condition that the flowing Mach number is changed. The invention realizes the maximum silencing effect on different grazing incidence sound waves by changing the offset distance between the resonance cavity and the neck short pipe.
The technical scheme is as follows: the invention relates to a cavity movable Helmholtz resonator, which comprises a main air inlet pipeline, wherein a neck short pipe which is vertically arranged with the main air inlet pipeline and is communicated with the main air inlet pipeline is fixedly arranged on the main air inlet pipeline, a rigid back plate is fixedly arranged at the end part of the neck short pipe, a movable cavity component is arranged on the rigid back plate, a resonance cavity which can slide on the movable cavity component is arranged on the movable cavity component, the interior of the resonance cavity is communicated with the neck short pipe, a system control module is also arranged at the upstream position of the main air inlet pipeline, the output end of the system control module is connected with a double-gear movable guide rod component, the double-gear movable guide rod component drives the resonance cavity to slide on the movable cavity component, the system control module is used for collecting the gas flow velocity in the main air inlet pipeline and controlling the double-gear movable guide rod component to move based on the collected gas, thereby changing the offset distance between the resonant cavity and the neck stub.
Furthermore, the movable cavity assembly comprises a linear track and a square perforated sliding block, the linear track is installed on the rigid back plate, and the square perforated sliding block is installed on the linear track in a sliding mode. The square perforated slide block can move smoothly left and right on the linear track.
Further, the resonance cavity is a hollow and bottomless cylindrical cavity.
Further, the system control module includes L type pitot tube, the one end of L type pitot tube is located the trunk line that admits air, and the other end of L type pitot tube is connected with the pitot tube instrument, the pitot tube instrument is connected with signal processor, step motor controller and step motor in proper order, install drive gear on step motor's the output shaft. The L-shaped pitot tube is installed at the upstream of the main air inlet pipeline and serves as the input end of the system control module, and the L-shaped pitot tube is used for detecting the flowing Mach number of the air in the main air inlet pipeline.
Furthermore, the double-gear movable guide rod assembly comprises a first gear and a second gear, the first gear is meshed with the transmission gear and the second gear respectively, a vertical guide rod is clamped on the second gear, and one end of the vertical guide rod is fixedly connected with the resonance cavity. The first gear drives the second gear to rotate, and then the second gear drives the vertical guide rod to move left and right, so that the offset distance between the resonance cavity and the neck short pipe is changed.
Furthermore, a clamping groove used for clamping the second gear is arranged on the vertical guide rod.
Furthermore, through holes corresponding to the inner positions of the neck short pipe are formed in the linear track and the rigid back plate.
The invention also provides a control method of the cavity movable Helmholtz resonator, which comprises the following steps:
(1) the method comprises the following steps that an L-shaped pitot tube measures the flow velocity of fluid in a main air inlet pipeline, displays the flow velocity on a pitot tube instrument, and then transmits data to a signal processor;
(2) the signal processor converts the signals transmitted by the L-shaped pitot tube into electric signals and transmits the electric signals to the stepping motor controller;
(3) the stepping motor controller controls the stepping motor to rotate through an electric signal, and the stepping motor drives the double-gear movable guide rod assembly to move through a transmission gear of the output shaft;
(4) the second gear in the double-gear moving guide rod component moves to drive the vertical guide rod to move, so that the resonance cavity moves, and the maximum silencing effect of different grazing incidence sound waves is realized by changing the offset distance between the resonance cavity and the neck short pipe.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
the invention converts the measured flow velocity signal through a series of signals by the L-shaped pitot tube, transmits the signals to the stepping motor, and drives the double-gear moving guide rod component to move, thereby controlling the offset distance between the resonance cavity and the neck short pipe and achieving the purpose that the Helmholtz resonator always keeps the best silencing performance under different flowing Mach numbers.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic view of a dual gear shift guide bar assembly;
FIG. 3 is a schematic view of a movable chamber assembly;
FIG. 4 is a partial enlarged view of the offset distance between the resonant cavity and the neck stub;
figure 5 is a graph of helmholtz transmission loss at different mach numbers of the swept flow and different eccentricities.
Detailed Description
The invention is further described below with reference to the following figures and examples:
as shown in fig. 1 to 5, the helmholtz resonator with a movable cavity of the present invention includes a main intake pipe 1, a neck pipe stub 2 vertically disposed with the main intake pipe 1 and communicated with the main intake pipe 1 is fixedly mounted on the main intake pipe 1, the neck pipe stub 2 is a hollow structure, a rigid back plate 3 is fixedly mounted at an end of the neck pipe stub 2, the rigid back plate 3 is perpendicular to the neck pipe stub 2, a movable cavity assembly 4 is mounted on the rigid back plate 3, a resonance cavity 5 capable of sliding on the movable cavity assembly 4 is mounted on the movable cavity assembly 4, the resonance cavity 5 is a hollow and bottomless cylindrical cavity, the interior of the resonance cavity 5 is communicated with the neck pipe stub 2, so that through holes 6 corresponding to the interior positions of the neck pipe stub 2 are respectively disposed on a linear track 41 and the rigid back plate 3;
the movable cavity assembly 4 comprises a linear track 41 and a square perforated slider 42, the linear track 41 is installed on the rigid backboard 3, the square perforated slider 42 is installed on the linear track 41 in a sliding manner, and the square perforated slider 42 can move smoothly on the linear track 41, namely, the resonance cavity 5 can be driven to move smoothly; the square perforated sliding block 42 is coaxially and hermetically connected with the resonance cavity 5, and the perforated diameter of the square perforated sliding block 42 is the same as that of the resonance cavity 5;
the system control module 7 is further installed at the upstream position of the main air inlet pipeline 1, the output end of the system control module 7 is connected with the double-gear moving guide rod assembly 8, the double-gear moving guide rod assembly 8 drives the resonance cavity 5 to slide on the moving cavity assembly 4, the system control module 7 is used for collecting the flow rate of gas in the main air inlet pipeline 1 and controlling the double-gear moving guide rod assembly 8 to move based on the collected flow rate of gas so as to drive the resonance cavity 5 to move, and therefore the offset distance between the resonance cavity 5 and the neck short pipe 2 is changed;
the system control module 7 comprises an L-shaped pitot tube 71, one end of the L-shaped pitot tube 71 is positioned in the main air inlet pipe 1, the other end of the L-shaped pitot tube 71 is connected with a pitot tube instrument 72, and the L-shaped pitot tube 71 is installed at the upstream of the main air inlet pipe 1 and serves as the input end of the system control module 7 and is used for detecting the gas flow Mach number in the main air inlet pipe 1;
the Mach number calculation formula is as follows:
wherein, cfMeasured by an L-shaped pitot tube 71 as a flow velocity, c is a sound velocity, K is a pitot tube coefficient, P is a dynamic pressure measured by the pitot tube, and rho is a fluid density;
the pitot tube instrument 72 is sequentially connected with a signal processor 73, a stepping motor controller 74 and a stepping motor 75, and a transmission gear is arranged on an output shaft of the stepping motor 75; the stepping motor 75 is used as the output end of the system control module 7, and the output shaft thereof is provided with a transmission gear which is meshed with the first gear 81 of the double-gear moving guide rod component 8;
the double-gear moving guide rod assembly 8 comprises a first gear 81 and a second gear 82, the first gear 81 is respectively meshed with the transmission gear and the second gear 82, a vertical guide rod 83 is clamped on the second gear 82, and one end of the vertical guide rod 83 is fixedly connected with the resonance cavity 5; the transmission gear on the output shaft of the stepping motor 75 drives the first gear 81 to rotate, the first gear 81 drives the second gear 82 to rotate, then the second gear 82 drives the vertical guide rod 83 to move, the offset distance between the resonance cavity 5 and the neck short pipe 2 is changed, and the vertical guide rod 83 is provided with a clamping groove 84 for clamping the second gear 82, so that when the second gear 82 rotates, the vertical guide rod 83 can only be driven to move left and right, but the vertical guide rod 83 cannot be driven to move up and down, and the operation stability of the device is ensured;
the offset distance between the resonant cavity 5 and the neck stub 2 is expressed in terms of eccentricity as:
wherein e iscRepresents the distance between the center of the bottom surface of the neck short pipe 2 and the center of the bottom surface of the resonant cavity 5, asRepresenting the radius of the bottom surface of the resonant cavity 5.
The invention also provides a control method of the cavity movable Helmholtz resonator, which comprises the following steps:
(1) the L-shaped pitot tube 71 measures the flow velocity of the fluid in the main intake air pipeline 1, displays the flow velocity on a pitot tube instrument 72 and then transmits data to a signal processor 73;
(2) the signal processor 73 converts the signal transmitted by the L-shaped pitot tube 71 into an electrical signal through a series of signal processing, and transmits the electrical signal to the stepping motor controller 74;
(3) the stepping motor controller 74 controls the stepping motor 75 to rotate through an electric signal, and the stepping motor 75 drives the double-gear moving guide rod 8 assembly to move through a transmission gear of an output shaft;
(4) the second gear 82 of the dual gear moving guide rod assembly 8 moves to drive the vertical guide rod 83 to move, so as to move the resonant cavity 5, by changing the offset distance (e) between the resonant cavity 5 and the neck pipe stub 2c/as) The maximum noise reduction effect on different grazing incidence sound waves is realized.
The specific method for the stepper motor controller 74 to control the rotation of the stepper motor 75 through the electrical signal is as follows: when different gas flowing Mach numbers in the main air inlet pipeline 1 detected by the L-shaped pitot tube 71 are detected, the stepping motor controller 74 controls the stepping motor 75 to rotate by different rotating amplitudes, then the stepping motor 75 is in a power-off state, the offset distance between the resonance cavity 5 and the neck short tube 2 is changed along with the different gas flowing Mach numbers, and the maximum silencing effect on different grazing incidence sound waves is achieved. Therefore, under the condition of different grazing flow Mach numbers, the offset distance between the cavity and the neck short pipe can be controlled within a certain range, and the purpose of better noise reduction is achieved.
Claims (8)
1. A kind of cavity movable Helmholtz resonator, characterized by that: the device comprises an air inlet main pipeline, wherein a neck short pipe which is vertically arranged with the air inlet main pipeline and is communicated with the air inlet main pipeline is fixedly arranged on the air inlet main pipeline, a rigid back plate is fixedly arranged at the end part of the neck short pipe, a movable cavity assembly is arranged on the rigid back plate, a resonance cavity which can slide on the movable cavity assembly is arranged on the movable cavity assembly, the inside of the resonance cavity is communicated with the neck short pipe, a system control module is also arranged at the upstream position of the air inlet main pipeline, the output end of the system control module is connected with a double-gear movable guide rod assembly, the double-gear movable guide rod assembly drives the resonance cavity to slide on the movable cavity assembly, the system control module is used for collecting the gas flow rate in the air inlet main pipeline and controlling the double-gear movable guide rod assembly to move based on the collected, thereby changing the offset distance between the resonant cavity and the neck stub.
2. A helmholtz resonator with movable cavity according to claim 1, characterized in that: the movable cavity assembly comprises a linear track and a square perforated sliding block, the linear track is installed on the rigid back plate, and the square perforated sliding block is installed on the linear track in a sliding mode.
3. A helmholtz resonator with movable cavity according to claim 1, characterized in that: the resonance cavity is a hollow cylindrical cavity without a bottom.
4. A helmholtz resonator with movable cavity according to claim 1, characterized in that: the system control module comprises an L-shaped pitot tube, one end of the L-shaped pitot tube is located in an air inlet main pipeline, the other end of the L-shaped pitot tube is connected with a pitot tube instrument, the pitot tube instrument is sequentially connected with a signal processor, a stepping motor controller and a stepping motor, and a transmission gear is installed on an output shaft of the stepping motor.
5. A Helmholtz resonator with a movable cavity according to claim 4, wherein: the double-gear movable guide rod assembly comprises a first gear and a second gear, the first gear is meshed with the transmission gear and the second gear respectively, a vertical guide rod is clamped on the second gear, and one end of the vertical guide rod is fixedly connected with the resonance cavity.
6. A Helmholtz resonator with a movable cavity according to claim 5, wherein: and a clamping groove for clamping the second gear is arranged on the vertical guide rod.
7. A helmholtz resonator with movable cavity according to claim 2, characterized in that: and through holes corresponding to the inner positions of the neck short pipes are formed in the linear track and the rigid back plate.
8. The method for controlling a Helmholtz resonator with a movable cavity according to claim 5, comprising the following steps:
(1) the method comprises the following steps that an L-shaped pitot tube measures the flow velocity of fluid in a main air inlet pipeline, displays the flow velocity on a pitot tube instrument, and then transmits data to a signal processor;
(2) the signal processor converts the signals transmitted by the L-shaped pitot tube into electric signals and transmits the electric signals to the stepping motor controller;
(3) the stepping motor controller controls the stepping motor to rotate through an electric signal, and the stepping motor drives the double-gear movable guide rod assembly to move through a transmission gear of the output shaft;
(4) the second gear in the double-gear moving guide rod component moves to drive the vertical guide rod to move, so that the resonance cavity moves, and the maximum silencing effect of different grazing incidence sound waves is realized by changing the offset distance between the resonance cavity and the neck short pipe.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110135328.4A CN112967708A (en) | 2021-02-01 | 2021-02-01 | Cavity-movable Helmholtz resonator and control method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110135328.4A CN112967708A (en) | 2021-02-01 | 2021-02-01 | Cavity-movable Helmholtz resonator and control method thereof |
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