RU139581U1 - NOISE DOWN SCREEN - Google Patents

Abstract

1. Noise-reducing screen, characterized in that it includes a hermetically connected panel and duct made of dense materials, and on the surface of the panel holes are made in the form of vertically arranged slots, while the profile of the duct is constructed so that the distance between the inner surfaces of the rear wall of the duct and the panel was unstable, and the width of the slit, its depth and the vertically varying distance between the inner surfaces of the back wall of the box and panel are selected so that, in accordance Corollary to zavisimostyugde h - distance between the inner surfaces of the panels and box rear wall, m; b - slot width, m; f is the resonant frequency, Hz; L is the distance between the cracks, m; l is the depth of the gap, m; c - the speed of sound in air at 20 ° С, to provide the required spectrum of absorbed frequencies. 2. A noise reduction screen according to claim 1, characterized in that the selection of the aspect ratio can be carried out in accordance with the dependence 3. Noise-reducing screen for PP. 1 and 2, characterized in that in addition, stiffeners are used that connect the box and the panel. 4. Noise-reducing screen for PP. 1-3, characterized in that the depth of the slit may have a profile of variable width. 5. Noise-reducing screen for PP. 1-3, characterized in that the width of the slit may have a profile of variable width. 6. Noise reducing screen according to any item, characterized in that the slot is provided with damping material.

Description

The claimed technical solution relates to noise reduction structures and, in particular, to noise insulation screen elements designed to protect urban areas from the negative noise effects of vehicles, industrial equipment, etc.

From the prior art, a panel is known from layered homogeneous sound-absorbing materials used in construction and engineering to protect a person from noise [1, pp. 71-75, Fig. 25]. Its disadvantage is the low sound absorption efficiency with a wide frequency range of the acoustic field.

The problem to which the claimed device is directed is to expand the ability to adapt the spectrum of the frequencies absorbed by the screen to the conditions of a specific urbanized area, which, in the final result, provides an increase in the effectiveness of protection against acoustic pollution.

, где h - расстояние между внутренними поверхностями панели и задней стенки короба, м; b - ширина щели, м; f - резонансная частота, Гц; L - расстояние между щелями, м; l - глубина щели, м; с - скорость звука в воздухе при 20°C, обеспечить требуемый спектр поглощаемых частот.This goal is achieved due to the fact that the screen is composed of hermetically connected panels and ducts made of dense materials, and on the surface of the panel holes are made in the form of vertically located slots, while the duct profile is constructed so that the distance between the inner surfaces of the rear wall of the duct and the panel was unstable, and the width of the slit, its depth and the vertically varying distance between the inner surfaces of the back wall of the box and panel are selected so that according to the relation

where h is the distance between the inner surfaces of the panel and the rear wall of the box, m; b - slot width, m; f is the resonant frequency, Hz; L is the distance between the cracks, m; l is the depth of the gap, m; c - the speed of sound in air at 20 ° C, to provide the required spectrum of absorbed frequencies.

.Additionally, the choice of aspect ratio can be carried out in accordance with the dependence

.

Additionally, the noise reduction screen may have stiffeners connecting the duct and panel to each other.

Additionally, slot perforation can be performed with a variable width profile.

Additionally, slot perforation can be performed with a variable depth profile.

Additionally, the slots may contain damping material.

The technical result provided by the given set of features is the possibility of adapting the spectral characteristics of the sound frequencies absorbed by the screen to the application conditions and increasing the efficiency of protection against acoustic noise pollution.

Figure 1 presents the noise reduction screen from the front panel. Figure 2 is a section A-A of figure 1, figure 3 is a section of a screen with damping material in the neck of the resonator, and figure 4 is a section of a screen with installed stiffeners.

The noise reduction screen consists of a panel 1 with holes 2, as well as a duct 3. In addition, stiffening ribs 4 and damping material 5 can be included in the device.

The tight connection of the panel 1 and the duct 3 creates a closed volume. The presence of slots 2 on the panel 1 provides the formation of a set of Helmholtz resonators, which allows the absorption (attenuation) of the acoustic noise signal to reach the screen installation area. The width and depth of the slit 2, the distance between the inner surfaces of the rear wall of the box 3 and panel 1 are determined based on the frequency range in which it is necessary to provide noise absorption. Thus, the device implements a set of slotted Helmholtz resonators. Upon reaching the installation zone of the noise absorber of the acoustic noise signal propagating in an urbanized environment, its absorption is ensured. The presence of stiffeners 4 increases the rigidity of the structure, increasing the ability of the resonators to absorb signals. The damping material 5 provides an increase in the active acoustic resistance and, as a consequence, the absorption coefficient of the resonator as a whole.

, где b - ширина щели, м; L - расстояние между отверстиями, м; h - расстояние между внутренними поверхностями панели и задней стенки короба, м; l -глубина щели, м; с - скорость звука в воздухе при 20°С [2, стр.66]. Проведя несложные преобразования, получим выражения для вычисления одного из определяемых параметров при заданных остальных, например

.The resonant frequency f of the Helmholtz resonator for the case of holes in the form of slots is determined by the expression

where b is the width of the slit, m; L is the distance between the holes, m; h is the distance between the inner surfaces of the panel and the rear wall of the box, m; l is the depth of the slit, m; C is the speed of sound in air at 20 ° C [2, p. 66]. After performing simple transformations, we obtain expressions for calculating one of the determined parameters for the given others, for example

.

With a known frequency range in which it is necessary to absorb, such a profile of the rear wall of the box or the dimensions of the slit can be formed, which ensures effective absorption of acoustic noise in the selected frequency range.

Information sources

1. E.Ya. Yudin et al. Sound-absorbing materials. - M.: Stroyizdat, 1966.

2. Bulkin V.V., Belyaev V.E., Sergeev V.N. Design calculations of elements of RES in the conditions of mechanical and acoustic influences: Textbook. allowance / Ed. V.V. Bulkin. - Murom: CPI MI VlSU, 2004.132 s.

Claims (6)

1. Noise-reducing screen, characterized in that it includes a hermetically connected panel and duct made of dense materials, moreover, holes are made in the form of vertically arranged slots on the surface of the panel, while the duct profile is constructed so that the distance between the inner surfaces of the rear wall of the duct and the panel was unstable, and the width of the slit, its depth and the vertically varying distance between the inner surfaces of the back wall of the box and panel are selected so that, in accordance Corollary addiction $$h=2.54\cdot {10}^{-2}\frac{b\cdot c^2}{f^2\cdot L\cdot l},$$

where h is the distance between the inner surfaces of the panel and the rear wall of the box, m; b - slot width, m; f is the resonant frequency, Hz; L is the distance between the cracks, m; l is the depth of the gap, m; c - the speed of sound in air at 20 ° С, to provide the required spectrum of absorbed frequencies. 2. Noise-reducing screen according to claim 1, characterized in that the choice of aspect ratio can be carried out in accordance with the dependence $$f=\frac{c}{2\pi }\sqrt{\frac{b}{L\cdot h\cdot l}}.$$

3. Noise-reducing screen for PP. 1 and 2, characterized in that additionally used stiffeners connecting the duct and the panel. 4. Noise reducing screen according to paragraphs. 1-3, characterized in that the depth of the slit may have a profile of variable width. 5. Noise-reducing screen for PP. 1-3, characterized in that the width of the slit may have a profile of variable width. 6. Noise reduction screen according to any item, characterized in that the slot is provided with damping material.

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