Acoustic Modeling of Charge Air Coolers

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Magnus Knutsson ◽  
Mats Åbom
Keyword(s):  
Gas Exchange ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Acoustic Properties ◽  
Passenger Cars ◽  
Air Intake ◽  
Ic Engines ◽  
Reactive Properties ◽  
Good Agreement

The necessity of reducing CO2 emissions has lead to an increased number of passenger cars that utilize turbocharging to maintain performance when the internal combustion (IC) engines are downsized. Charge air coolers (CACs) are used on turbocharged engines to enhance the overall gas exchange efficiency. Cooling of charged air increases the air density and thus the volumetric efficiency and also increases the knock margin (for petrol engines). The acoustic properties of charge coolers have so far not been extensively treated in the literature. Since it is a large component with narrow flow passages, it includes major resistive as well as reactive properties. Therefore, it has the potential to largely affect the sound transmission in air intake systems and should be accurately considered in the gas exchange optimization process. In this paper, a frequency domain acoustic model of a CAC for a passenger car is presented. The cooler consists of two conical volumes connected by a matrix of narrow ducts where the cooling of the air takes place. A recently developed model for sound propagation in narrow ducts that takes into account the attenuation due to thermoviscous boundary layers and interaction with turbulence is combined with a multiport representation of the tanks to obtain an acoustic two-port representation where flow is considered. The predictions are compared with experimental data taken at room temperature and show good agreement. Sound transmission loss increasing from 5 to over 10 dB in the range 50–1600 Hz is demonstrated implying good noise control potential.

scholarly journals 3D Acoustic Modelling of Dissipative Silencers with Nonhomogeneous Properties and Mean Flow

2014 ◽  
Vol 6 ◽  
pp. 537935 ◽  
Author(s):  
E. M. Sánchez-Orgaz ◽  
F. D. Denia ◽  
J. Martínez-Casas ◽  
L. Baeza
Keyword(s):  
Bulk Density ◽  
Acoustic Analysis ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Acoustic Properties ◽  
Mean Flow ◽  
Absorbent Material ◽  
Outer Chamber ◽  
Nonhomogeneous Properties ◽  
Flow Effects

A finite element approach is proposed for the acoustic analysis of automotive silencers including a perforated duct with uniform axial mean flow and an outer chamber with heterogeneous absorbent material. This material can be characterized by means of its equivalent acoustic properties, considered coordinate-dependent via the introduction of a heterogeneous bulk density, and the corresponding material airflow resistivity variations. An approach has been implemented to solve the pressure wave equation for a nonmoving heterogeneous medium, associated with the problem of sound propagation in the outer chamber. On the other hand, the governing equation in the central duct has been solved in terms of the acoustic velocity potential considering the presence of a moving medium. The coupling between both regions and the corresponding acoustic fields has been carried out by means of a perforated duct and its acoustic impedance, adapted here to include absorbent material heterogeneities and mean flow effects simultaneously. It has been found that bulk density heterogeneities have a considerable influence on the silencer transmission loss.

scholarly journals Development and Investigation of Fully Ventilated Deep Subwavelength Absorbers

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1835
Author(s):  
Heng Wang ◽  
Qibo Mao
Keyword(s):  
Theoretical Model ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Acoustic Metamaterial ◽  
Acoustic Performance ◽  
Half Wave ◽  
Quarter Wave ◽  
New Type ◽  
Good Agreement

A new type of deep subwavelength acoustic metamaterial (AMM) absorber with 100% ventilation is presented in this study. The proposed ventilation absorber consists of coiled-up half-wave resonators (HWRs) and quarter-wave resonators (QWRs). First, the sound absorption and sound transmission performances for absorbers were analyzed considering the thermal viscosity dissipation. Then, the prototype with ten HWRs and three QWRs composed of acrylic plates was manufactured based on the theoretical model. The acoustic performance of the absorber was tested in an air-filled acoustic impedance tube to determine the sound absorption and transmission loss performances. Good agreement was found between the measured and theoretically predicted results. The experimental results show that the proposed ventilation AMM absorber is able to achieve sound absorption in a range between 330 Hz and 460 Hz with a thickness of only 32 mm (about 3% of the wavelength in the air). Furthermore, the sound transmission loss can achieve 17 dB from 330 Hz to 460 Hz. The main advantage of the proposed absorber is that it can be completely ventilated in duct noise control.

Experimental Study of Sound Transmission Loss in Electrorheological Liquids

2002 ◽  
Author(s):  
Marek L. Szary ◽  
Maciej Noras
Keyword(s):  
Electric Field ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Active Vibration Control ◽  
Sound Transmission ◽  
Sound Transmission Loss ◽  
Frequency Range ◽  
Field Density ◽  
Active Vibration ◽  
College Of Engineering

Electrorheological (ER) liquids possess the ability to change their physical properties like the apparent viscosity and modulus of elasticity under the influence of an external electric field. They serve successfully in the field of active vibration control—as well as in many other areas. In the Acoustic Laboratory at the College of Engineering, Southern Illinois University in Carbondale, research on the possibility of applying ER liquids to the control of a sound transmission loss (STL) was conducted. The STL was investigated for various kinds of ER suspensions in the frequency range 100 Hz to 2 kHz. An influence of the electric field density on the STL was different for normal and shear stress developed by DC voltage. In both cases the STL decreased with the increasing electric field density. These properties could be potentially useful in sound propagation control applications.

Characterizing the Sound Insulation of a Specially Orthotropic Multi-Layered Medium

2007 ◽  
Vol 23 (1) ◽  
pp. 63-68 ◽  
Author(s):  
H.-J. Lin ◽  
C.-N. Wang ◽  
Y.-M. Kuo
Keyword(s):  
Boundary Conditions ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Single Layer ◽  
Sound Insulation ◽  
Sound Transmission Loss ◽  
Reinforced Plastics ◽  
Fiber Reinforced Plastics ◽  
Sound Transmission Class

AbstractThis work explores the sound transmission loss provided by the orthotropic multi-layers to elucidate the sound insulation of FRP (Fiber Reinforced Plastics). Mat is the major material considered in the numerical works. The transfer matrices of a single layer of the orthotropic laminate and the fluid are determined. Further, the boundary conditions on the various interface planes are arranged into matrix form. Combining the transfer matrixes and the boundary conditions and applying the transfer matrix method (TMM) yields the surface impedance and the sound transmission loss. The sound-propagation characteristics are studied. Additionally, the STC (Sound Transmission Class) of FRP and steel are compared and discussed.

Incorporation of Nanofiber Layers in Nonwoven Materials for Improving Their Acoustic Properties

2013 ◽  
Vol 8 (4) ◽  
pp. 155892501300800 ◽  
Author(s):  
Amir Rabbi ◽  
Hossein Bahrambeygi ◽  
Ahmad Mousavi Shoushtari ◽  
Komeil Nasouri
Keyword(s):  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Wide Band ◽  
Acoustic Properties ◽  
Sound Insulation ◽  
Sound Transmission Loss ◽  
Factors Affecting ◽  
Nonwoven Materials ◽  
Field Noise

Due to numerous developments in most industries and the increase in the usage of massive and powerful machines in every field, noise has become an unavoidable part of mechanized life and has brought about serious health hazards. The main aim of this work was to investigate the usability of polyurethane and polyacrylonitrile nanofibers for improving sound insulation properties over a wide band of frequencies and reducing weight and thickness of conventional polyester and wool nonwovens. The effect of the number of nanofiber layers and associated surface densities on acoustic properties was investigated. Sound transmission loss and sound absorption analysis using the impedance tube method were carried out as the main factors affecting acoustic behavior of samples. The results show that incorporation of nanofiber layers in nonwoven materials can improve both sound absorption and sound transmission loss simultaneously, especially in mid and lower frequencies, which are difficult to detect by conventional materials.

scholarly journals Analyzing and evaluation of effective parameters on sound transmission loss of the triple-layered acoustic panels with sound-absorbing middle layer

2015 ◽  
Vol 4 (2) ◽  
pp. 250
Author(s):  
Nader Mohammadi
Keyword(s):  
Boundary Condition ◽  
Porous Material ◽  
Elastic Layer ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Air Gap ◽  
Acoustic Properties ◽  
Sound Transmission Loss ◽  
Static Young’S Modulus ◽  
Wide Range

In this research, a triple-layered acoustic panel with sound-absorbing intermediate layer materials is modeled analytically in order to calculate the sound transmission loss in the normal incidence field. This information provides an appropriate platform for optimum noise control. In this paper, porous material is used as an absorbent layer between two elastic panels. In modeling these triple-layered panels, theory of wave propagation in porous materials is used and bounded boundary condition of the first elastic layer and unbounded boundary condition of the second elastic layer is applied. To validate the model, the results of this model are compared with the results of the Bolton. Comparison of results revealed very good compatibility. Here, the effect of the length of the air gap between the elastic layers, density and the material of the elastic plate, the thickness and vibro-acoustic properties of the intermediate porous material on the values of transmission loss is investigated.In a wide range of frequencies, increasing air gap, density of elastic panels and porous layer thickness, increase the transmission loss up to 10 dB. At frequencies above 10 kHz, a reduction in porosity, static Young's modulus, the loss coefficient, increasing bulk density of the solid phase, the factor of geometrical structure and viscosity of porous material, increase the sound transmission loss up to 15 dB.

Low frequency acoustic properties of a honeycomb-silicone rubber acoustic metamaterial

2017 ◽  
Vol 31 (11) ◽  
pp. 1750118 ◽  
Author(s):  
Nansha Gao ◽  
Hong Hou
Keyword(s):  
Silicone Rubber ◽  
Transmission Loss ◽  
Layer Structure ◽  
Low Frequency ◽  
Sound Transmission ◽  
Honeycomb Structure ◽  
Acoustic Properties ◽  
Sound Insulation ◽  
Control Zone ◽  
Acoustic Metamaterial

In order to overcome the influence of mass law on traditional acoustic materials and obtain a lightweight thin-layer structure which can effectively isolate the low frequency noises, a honeycomb-silicone rubber acoustic metamaterial was proposed. Experimental results show that the sound transmission loss (STL) of acoustic metamaterial in this paper is greatly higher than that of monolayer silicone rubber metamaterial. Based on the band structure, modal shapes, as well as the sound transmission simulation, the sound insulation mechanism of the designed honeycomb-silicone rubber structure was analyzed from a new perspective, which had been validated experimentally. Side length of honeycomb structure and thickness of the unit structure would affect STL in damping control zone. Relevant conclusions and design method provide a new concept for engineering noise control.

scholarly journals Effect of Subsurface Mediterranean Water Eddies on Sound Propagation Using ROMS Output and the Bellhop Model

Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3617
Author(s):  
Seyed Hossein Hassantabar Bozroudi ◽  
Daniele Ciani ◽  
Mahdi Mohammad Mahdizadeh ◽  
Mohammad Akbarinasab ◽  
Ana Claudia Barbosa Aguiar ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Acoustic Energy ◽  
Acoustic Properties ◽  
Angular Distributions ◽  
Northeastern Atlantic Ocean ◽  
Mediterranean Water ◽  
Northeastern Atlantic

Ocean processes can locally modify the upper ocean density structure, leading to an attenuation or a deflection of sound signals. Among these phenomena, eddies cause significant changes in acoustic properties of the ocean; this suggests a possible characterization of eddies via acoustics. Here, we investigate the propagation of sound signals in the Northeastern Atlantic Ocean in the presence of eddies of Mediterranean Water (Meddies). Relying on a high-resolution simulation of the Atlantic Ocean in which Meddies were identified and using the Bellhop acoustic model, we investigated the differences in sound propagation in the presence and absence of Meddies. Meddies create sound channels in which the signals travel with large acoustic energy. The transmission loss decreases to 80 or 90 dB; more signals reach the synthetic receivers. Outside of these channels, the sound signals are deflected from their normal paths. Using receivers at different locations, the acoustic impact of different Meddies, or of the same Meddy at different stages of its life, are characterized in terms of angular distributions of times of arrivals and of energy at reception. Determining the influence of Meddies on acoustic wave characteristics at reception is the first step to inverting the acoustic signals received and retrieving the Meddy hydrological characteristics.

scholarly journals Utilisation of High Energy Propellant Waste in Manufacturing of Fired Clay Bricks to Enhance the Acoustic Properties

2021 ◽  
Vol 71 (5) ◽  
pp. 639-646
Author(s):  
P.K. Mehta ◽  
A. Kumaraswamy ◽  
V.K. Saraswat ◽  
B. Praveen Kumar
Keyword(s):  
Waste Management ◽  
Transmission Loss ◽  
Experimental Studies ◽  
Sound Transmission ◽  
High Energy ◽  
Environmental Hazards ◽  
Acoustic Properties ◽  
Sound Transmission Loss ◽  
Clay Bricks ◽  
Directional Orientation

The disposal and waste management of solid high energy propellant (HEP) is a considerate conservational problem. HEP waste is currently disposed in open or confined burning which may cause environmental hazards. In this paper, we examined and discussed results on recycling of HEP waste into fired clay bricks baked in different orientation. HEP modified bricks with 1.5%, 3% and 5 wt. % HEP waste content were manufactured and tested, and then compared against virgin clay bricks without HEP content. The effect of directional orientation of bricks baked with varying HEP content on acoustic properties were experimented and discussed. The sound transmission loss decreases with increase in HEP waste due to formation of independently closed directional pores. The transmission loss of horizontally baked during firing of bricks is nearly 5dB lower than vertically baked bricks. Results of the experimental studies indicate that HEP waste can be utilised in fired clay bricks and different orientation baking further enhances the acoustic properties.

scholarly journals Ultralight Graphene Oxide/Polyvinyl Alcohol aerogel for broadband and tuneable acoustic properties

2021 ◽  
Author(s):  
Mario Rapisarda ◽  
Gian-Piero Malfense Fierro ◽  
Michele Meo
Keyword(s):  
Graphene Oxide ◽  
Polyvinyl Alcohol ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Acoustic Properties ◽  
Low Density ◽  
Transmission Losses ◽  
New Class ◽  
Processing Times

Abstract An ultralight Graphene Oxide/Polyvinyl Alcohol (GO/PVA) aerogel is proposed as a new class of acoustic materials with tuneable and broadband sound absorption and transmission loss. The interaction between GO sheets and PVA molecules are exploited in our environmentally friendly manufacturing process to fabricate aerogels with hierarchical and tuneable porosity embedded in a honeycomb scaffolding. The developed aerogels show an enhanced dissipation of sound energy, with an extremely low density of 2.10 kg m-3 , one of the lowest values ever reported for acoustic materials. We have first experimentally evaluated and optimized the effects of composition and thickness on the acoustic properties, namely sound absorption and sound transmission losses. Subsequently, we have employed a semi-analytical approach to evaluate the effect of different processing times and find the relationships between the acoustic and non-acoustic properties of the materials. Over the 400 – 2500 Hz range, the reported average sound absorption coefficients are as high as 0.79 for low density aerogels, while the average sound transmission losses can reach 15.8 dB for higher density aerogels. We envision our subwavelength aerogel-based design, tailored at achieving optimal acoustic performance, as a novel lightweight material for advanced engineering applications.

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