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Thin film type Helmholtz muffler

A technology of Helmholtz cavity and muffler, which is applied in the direction of sensors, sensor parts, frequency/direction characteristic devices, etc., can solve the problems of narrow frequency range of noise reduction and increase the range of noise reduction frequency band, and achieve the increase of noise reduction frequency range , Solve the effect of the narrow frequency range of noise reduction

Pending Publication Date: 2019-02-22
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

By setting multiple Helmholtz cavities in the muffler, the range of the anechoic frequency band can be further increased, effectively solving the problem that the anechoic frequency range is too narrow

Method used

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  • Thin film type Helmholtz muffler
  • Thin film type Helmholtz muffler
  • Thin film type Helmholtz muffler

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Experimental program
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Embodiment 1

[0028] Figure 5 , Figure 6 As shown, the present invention provides a film-type Helmholtz muffler, the muffler includes a cylindrical pipe body with a diameter of r, and the middle part of the cylindrical pipe body is a rectangular intermediate pipe; the cylindrical pipe body The axial direction of the inner extension tube body is coaxially provided with several layers of films, and the inside of the cylindrical tube body is cut along the axial direction of the tube body and divided into several Helmholtz cavities.

[0029] Further, the intermediate pipe runs through the cylindrical pipe body, and its length is greater than the thickness of the cylindrical pipe body.

[0030] Further, the cylindrical tube body includes four equally divided Helmholtz cavities.

[0031] As a preference, the inside of the cylindrical tube body is provided with less than or equal to three film layers along the axial direction of the tube body and coaxially.

[0032] The novel thin-film Helmho...

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Abstract

The invention proposes a novel thin film type Helmholtz muffler. The location of a muffling frequency band is changed by changing the number of thin films in the muffler, and the muffling frequency iseffectively approached to low frequency without changing the volume of a hollow cavity. A plurality of Helmholtz cavities are disposed in the muffler, so that the range of the muffling frequency bandcan be further increased, and the problem that the muffling frequency range is too narrow is effectively solved.

Description

technical field [0001] The invention relates to the technical field of low-frequency noise reduction devices, in particular to a film-type Helmholtz noise reduction device, which acts on the surface of a submarine and plays the role of low-frequency noise reduction within a certain frequency range. Background technique [0002] The traditional Helmholtz muffler usually consists of a closed cavity and a long neck. Since the volume of the neck is much smaller than the volume of the cavity, it can be approximated that the fluid in the neck is incompressible. However, the volume of the cavity can be compressed and can be regarded as a spring. When the excitation frequency is close to the frequency of the resonant cavity, the response of the bulk modulus type will be excited, thereby achieving the purpose of noise reduction. Due to the traditional Helmholtz type muffler With simple structure and high noise reduction, it is widely used to suppress the sound transmission in the ven...

Claims

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Application Information

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IPC IPC(8): H04R1/28
CPCH04R1/2869
Inventor 邵瀚波陈岩何欢陈国平何晋丞陈腾飞
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS