Considerations for the Reduction of Noise in Ship Installations of Gas Turbines

1960 ◽  
Vol 82 (3) ◽  
pp. 205-214
Author(s):  
Edward M. Herrmann
Keyword(s):  
Noise Reduction ◽  
Gas Turbines ◽  
Sound Absorption ◽  
Sound Insulation ◽  
Specific Information ◽  
Airborne Sound

General noise reduction considerations for shipboard installation of gas turbines are discussed. Specific information relating to sound-absorption materials, duct treatments, structureborne sound isolation, and airborne sound insulation is graphically presented.

scholarly journals Методы определения характеристик звукопоглощения строительных материалов и звукоизоляции конструкций (обзор)

2020 ◽  
Vol 45 (4) ◽  
Author(s):  
Keyword(s):  
Noise Reduction ◽  
Sound Absorption ◽  
Building Materials ◽  
Developed Countries ◽  
Reduction Factor ◽  
Sound Insulation ◽  
Reverberation Chamber ◽  
Normative Documents ◽  
Urban Conditions ◽  
First Time

Исследование акустических характеристик строительных материалов и конструкций необходимо для комфортной жизни людей в городских условиях. Несмотря на то что в нормативных документах развитых государств есть ряд методов их определения, единого понимания самих характеристик и путей их адекватного определения до сих пор нет. В настоящей работе мы попытались систематизировать и дать критический обзор нормативных документов, содержащих методы определения звукопоглощающих свойств материалов и звукоизоляционных характеристик конструкций. Впервые выявлены присущие разным методам закономерности определения характеристик звукопоглощения и звукоизоляции. Определены наиболее характерные показатели звукопоглощения. Произведено ранжирование по коэффициенту уменьшения шума NRC наиболее часто применяемых строительных материалов. Названы области применения рассматриваемых методик, проанализированы их преимущества и ограничения. Ключевые слова: коэффициент уменьшения шума, звукопоглотитель, импедансная труба, реверберационная камера The study of the acoustic characteristics of building materials and structures is necessary for provision of comfortable life of people in urban conditions. Despite the fact that in the normative documents of developed countries there are a number of methods for their determination, there is still no common understanding of the characteristics themselves and the ways of their adequate determination. In this work we tried to systematize and give a critical review of regulatory documents containing the methods for determining the sound-absorbing properties of materials and the sound-insulating characteristics of structures. For the first time the regularities in determination the characteristics of sound absorption and sound insulation inherent in different methods have been revealed. The most characteristic indicators of sound absorption have been determined. The ranking of the most commonly used building materials was made according to the noise reduction factor (NRC). The areas of application of the considered methods are presented, their advantages and limitations are analyzed. Keywords: noise reduction factor, sound absorber, impedance tube, reverberation chamber

Empirical study on the correlation between measurement methods under diffuse and direct sound field conditions for determining sound absorption and airborne sound insulation properties of noise barriers

2021 ◽  
Vol 263 (3) ◽  
pp. 3350-3361
Author(s):  
Andreas Fuchs ◽  
Reinhard Wehr ◽  
Marco Conter
Keyword(s):  
Empirical Study ◽  
Sound Absorption ◽  
Sound Field ◽  
Research Programme ◽  
Measurement Methods ◽  
Field Conditions ◽  
Acoustic Properties ◽  
Sound Insulation ◽  
Noise Barriers ◽  
Airborne Sound

In the frame of the SOPRANOISE project (funded by CEDR in the Transnational Road Research Programme 2018) the database of the European noise barrier market developed during the QUIESST project was updated with newly acquired data. This database gives the opportunity for an empirical study on the correlation between the different measurement methods for the acoustic properties of noise barriers (according to the EN 1793 series) to further investigate the interrelationships between these methods by using single-number ratings and third-octave band data. First a correlation of the measurement methods for sound absorption under diffuse field conditions (EN 1793-1) and sound reflection under direct sound field conditions (EN 1793-5) is presented. Secondly, a correlation of the measurement methods for airborne sound insulation under diffuse field conditions (EN 1793-2) and airborne sound insulation under direct sound field conditions (EN 1793-6) is shown. While for airborne sound insulation a distinct correlation is found due to the wide data range, for sound absorption no robust correlation can be found.

Research and Application of Building Enclosing Structure Used in Equipment Noise Control

2013 ◽  
Vol 423-426 ◽  
pp. 1272-1278
Author(s):  
Nan Xu
Keyword(s):  
Porous Material ◽  
Sound Absorption ◽  
Noise Control ◽  
Building Envelope ◽  
Sound Insulation ◽  
Hard Material ◽  
Noise Elimination ◽  
Control Engineering ◽  
Airborne Sound ◽  
Properties Of Materials

Porous material has a function of sound absorption, dense hard material can prevent the spread of airborne sound. The building envelope which is made up of different properties of materials, with good effects on sound insulation, sound absorption and noise elimination, can be widely used in noise control engineering.

An Alternative Method for Measurement of Airborne Sound Insulation

2001 ◽  
Vol 8 (1) ◽  
pp. 57-74 ◽  
Author(s):  
Karl-Ola Lundberg
Keyword(s):  
Transmission Coefficient ◽  
Impulse Response ◽  
Physical System ◽  
Sound Absorption ◽  
Sound Insulation ◽  
Power Balance ◽  
Propagation Time ◽  
Time Varying ◽  
Airborne Sound ◽  
Absorption Area

A method for determination of the transmission coefficient from Complex Modulation Transfer Functions CMTF:s based on measured impulse-responses is shown. In the method a separate measurement of the equivalent sound absorption area is not needed in contrast to in the standardised measurement. By averaging over a number of estimates of the impulse-response the influence of background noise can be reduced substantially, implying that low-power sources can be used. A model for the power balance in the receiving room with time-varying power is considered. In the model the quotient of the receiving room intensity and the source room intensity has one pole, which is proportional to the equivalent sound absorption area in the receiving room, and a gain, proportional to the transmission coefficient. In the physical system the power can be time-varied by letting the system excitation signal consist of random noise modulated with a deterministic time-varying function. However, since the ensemble average of the squared response is proportional to the squared impulse-response convolved with the squared modulating function, random excitation is avoided and replaced by impulse-response measurements. The quotient of intensities in the model is in the physical system a quotient of CMTF:s. Experiments are carried out in an airborne sound insulation laboratory. For comparison, standardised measurements are also carried out. It is found that the presented method gives as result comparatively small transmission coefficients, though the relative differences are small. By refining the power balance model by introducing an energy propagation time delay, and selecting an appropriate delay, the differences were diminished.

Theoretical End Experimental Evaluation of Perforations Effect on Sound Insulation

2017 ◽  
Author(s):  
Olga Khrystoslavenko ◽  
Raimondas Grubliauskas
Keyword(s):  
Noise Reduction ◽  
High Frequency ◽  
Sound Absorption ◽  
Low Frequency ◽  
Experimental Methods ◽  
Glass Wool ◽  
Acoustic Properties ◽  
Sound Insulation ◽  
Frequency Noise ◽  
Sound Reduction

To design a sound-absorbing panel, it is important to identify factors that affect the maximum sound absorption of low, middle and high frequency sounds. Perforation effect is very important for the noise-reducing and noiseabsorbing panels. Perforations are often used for sound reduction. Experimental data shows that the perforation is very effective to absorb low-frequency noise. In the presented study, influence of perforation coefficient of noise reduction was analyzed with theoretical and experimental methods. The experiments were conducted in noise reduction chamber using an perforated construction with glass wool filler. Sound reductions index of 15 dB indicates good acoustic properties of the panel.

scholarly journals Sound-Absorption Coefficient of Bark-Based Insulation Panels

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1012 ◽  
Author(s):  
Eugenia Mariana Tudor ◽  
Anna Dettendorfer ◽  
Günther Kain ◽  
Marius Catalin Barbu ◽  
Roman Réh ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Noise Reduction ◽  
Sound Absorption ◽  
Residential Buildings ◽  
Coarse Grained ◽  
Sound Absorption Coefficient ◽  
Sound Insulation ◽  
Formaldehyde Resin ◽  
Frequency Interval ◽  
Spruce Bark

The objective of this study was to investigate the sound absorption coefficient of bark-based insulation panels made of softwood barks Spruce (Picea abies (L.) H. Karst.) and Larch (Larix decidua Mill.) by means of impedance tube, with a frequency range between 125 and 4000 Hz. The highest efficiency of sound absorption was recorded for spruce bark-based insulation boards bonded with urea-formaldehyde resin, at a level of 1000 and 2000 Hz. The potential of noise reduction of larch bark-based panels glued with tannin-based adhesive covers the same frequency interval. The experimental results show that softwood bark, an underrated material, can substitute expensive materials that involve more grey energy in sound insulation applications. Compared with wood-based composites, the engineered spruce bark (with coarse-grained and fine-grained particles) can absorb the sound even better than MDF, particleboard or OSB. Therefore, the sound absorption coefficient values strengthen the application of insulation panels based on tree bark as structural elements for the noise reduction in residential buildings, and concurrently they open the new ways for a deeper research in this field.

scholarly journals A Novel Acoustic Sandwich Panel Based on Sheep Wool

Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 148
Author(s):  
Daniela-Roxana Tămaş-Gavrea ◽  
Tünde-Orsolya Dénes ◽  
Raluca Iştoan ◽  
Ancuţa Elena Tiuc ◽  
Daniela Lucia Manea ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Sandwich Panel ◽  
Bending Strength ◽  
Hydrated Lime ◽  
Acoustic Properties ◽  
Sound Insulation ◽  
Partition Wall ◽  
Airborne Sound ◽  
Composite Face ◽  
Sheep Wool

The aim of this paper is to propose a novel sandwich panel, which would be suitable for sound absorption and airborne sound insulation, used as applied cladding or independent lightweight partition wall. As far as the authors are concerned, this is the first sheep wool-based sandwich panel using only natural materials. The structure was prepared using hydrated lime-based composite face sheets and a sheep wool-based core. Several parameters of the sandwich panel were determined, including sound absorption coefficient, airborne sound insulation, thermal conductivity, thermal resistance, compressive strength, and bending strength, respectively. The results indicate that the maximum sound absorption value of 0.903 was obtained at the frequency of 524 Hz in the case of the unperforated sample, 0.822 at 536 Hz in the case of the sample with 10% perforations, 0.780 at 3036 Hz in the case of the sample with 20% perforations, and 0.853 at 3200 Hz in the case of the sample with 30% perforations. The registered airborne sound insulation index of the panel was 38 dB. Based on the obtained data, it can be concluded that the studied panel recorded comparable values with other synthetic noise control solutions, which are suitable as applied cladding or an independent lightweight partition wall, with good acoustic properties.

Study on Sound Insulation Performance of Pressure Relief Wall of Transformer Chamber

2021 ◽  
Vol 263 (1) ◽  
pp. 5197-5202
Author(s):  
Fabing Rong ◽  
Zhongjie Cheng ◽  
Peijie Liu
Keyword(s):  
Noise Reduction ◽  
Sound Absorption ◽  
Vibration Isolation ◽  
Noise Control ◽  
Sound Insulation ◽  
Noise Emission ◽  
Pressure Relief ◽  
Actual Case ◽  
Noise Interference ◽  
Insulation Performance

The problem of noise nuisance in indoor substation becomes more and more sensitive. The noise emission index of substation has become an important technical index of substation design. The noise control of indoor substation mainly adopts "auxiliary noise reduction technology" such as sound absorption, sound insulation and vibration isolation. The sound insulation performance of the pressure relief wall in the main transformer room of indoor substation is the key link of noise control. In order to reduce the noise interference, this paper selects the common sound insulation structure of the pressure relief wall, analyzes the main influencing factors of noise reduction, selects the sound insulation structure suitable for the pressure relief wall in the main transformer room of indoor substation, and tests the effectiveness of noise reduction of the sound insulation structure in the actual case. Based on the research results, the sound absorption structure in the main transformer room is arranged on the other indoor wall outside the pressure relief wall, and the pressure relief wall mainly considers the structure of sound insulation, which can effectively reduce the noise impact of the main transformer room.

Noise Character of Cooling Tower and Control Discussion

2012 ◽  
Vol 217-219 ◽  
pp. 2674-2677
Author(s):  
Huan Liu ◽  
Chang Zheng Chen ◽  
Hao Zhou
Keyword(s):  
Noise Reduction ◽  
Sound Absorption ◽  
Cooling Tower ◽  
Noise Control ◽  
Sound Insulation ◽  
Controlling Measures ◽  
And Control

This article takes the noise control of a cooling tower for a residence area as an example. On the base of measuring data, the noise resource is analyzed and the character of the noise resource is discussed. In the aspects of sound elimination, sound absorption and sound insulation, a set of practical controlling measures are elaborated. The result shows that the effect of noise reduction in this scheme is evident, and in the meantime the wind volume and temperature for the equipment are satisfying as well. Perfect effects of noise reduction can be obtained in the working project.

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