Sound absorption characterization of aluminum foam made by press infiltration casting

2016 ◽  
Vol 12 (4) ◽  
pp. 737-747 ◽  
Author(s):  
J.X. Sun ◽  
C.Y. Duan ◽  
P.S. Liu
Keyword(s):  
Experimental Data ◽  
Absorption Coefficient ◽  
Sound Wave ◽  
Sound Absorption ◽  
Aluminum Foam ◽  
Peak Frequency ◽  
Experimental Result ◽  
Content Type ◽  
Improved Model ◽  
Good Agreement

Purpose The purpose of this paper is to investigate the sound absorption by modeling for the aluminum foam produced by press infiltration casting. Design/methodology/approach First use Johnson-Allard-Champoux (JAC) model to calculate the sound absorption coefficient of the present aluminum foam, and then improve it after finding its deviation from the experimental data, so as to get an improved model that could have a good agreement with the experimental result. Findings Using JAC model to calculate the sound absorption coefficient of the present aluminum foam, it is found that the model may have a good agreement with the experimental data only for the sound wave frequency below the absorption peak frequency, but a large deviation from the experimental result for the sound wave frequency above this frequency. Originality/value Improving JAC model by means of two factors, i.e., the absorption peak frequency and the specific surface area, the resultant improved model could be in good agreement with the experimental data.

Research on Dropwise Condensation for Binary Mixed Vapor

2012 ◽  
Vol 190-191 ◽  
pp. 1355-1360
Author(s):  
Shen Hua Hu ◽  
Xiang Rong Ma ◽  
Fan Wu
Keyword(s):  
Experimental Data ◽  
Size Distribution ◽  
Mass Concentration ◽  
Drop Size ◽  
Pure Water ◽  
Maximum Error ◽  
Vertical Surface ◽  
Experimental Result ◽  
Vapor Velocity ◽  
Good Agreement

An experiment for Marangoni condensation of ethanol-water mixtures was carried out and the departing radius and drop size distribution on vertical surface was presented. An amended formula was obtained after considering the effect of ethanol mass concentration, vapor velocity and condensing temperature difference based on Le Fevre’s formula concerning departing radius of pure water, The calculations were in good agreement with experimental result, had a maximum error less than 23%. Owing to the significant effect on drop size contribution, vapor velocity was introduced into Rose’s formula, and the correctional result compared well with the experimental data.

THEORY OF THE PRESSURE-INDUCED ROTATIONAL SPECTRUM OF HYDROGEN

1959 ◽  
Vol 37 (10) ◽  
pp. 1187-1198 ◽  
Author(s):  
J. Van Kranendonk ◽  
Z. J. Kiss
Keyword(s):  
Experimental Data ◽  
Distribution Function ◽  
Absorption Coefficient ◽  
Pair Distribution Function ◽  
Wave Functions ◽  
Rotational Line ◽  
Induction Effect ◽  
Rotational Spectrum ◽  
Absorption Coefficients ◽  
Good Agreement

The theory of induced infrared absorption developed previously is applied to the pressure-induced rotational spectrum of hydrogen. The intensity of the rotational band is due mainly to the quadrupolar induction effect, and to a small interference effect between the quadrupolar and overlap moments. From the experimental data on the binary absorption coefficients, values of the angle-dependent overlap moments are obtained for H2–He, H2–H2, H2–Ne, H2–N2, and H2–A. A calculation of the overlap moment for pure H2 is presented. Rosen-type wave functions appear to be inadequate for a calculation of the small angle-dependent rotational as well as vibrational overlap moments. The temperature dependence of the binary absorption coefficient is calculated, taking into account the quantum effects in the pair distribution function, and found to be in good agreement with the experimental data. The dependence on the ortho–para ratio is also discussed. The double rotational line S(1) + S(1) has been observed and its intensity measured.

A theoretical model to study melting of metals under pressure

2015 ◽  
Vol 29 (27) ◽  
pp. 1550161 ◽  
Author(s):  
Kuldeep Kholiya ◽  
Jeewan Chandra
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Melting Temperature ◽  
Present Model ◽  
Melting Curve ◽  
Experimental Result ◽  
Thermal Equation ◽  
Simple Theoretical Model ◽  
Pressure Melting ◽  
Good Agreement

On the basis of the thermal equation-of-state a simple theoretical model is developed to study the pressure dependence of melting temperature. The model is then applied to compute the high pressure melting curve of 10 metals (Cu, Mg, Pb, Al, In, Cd, Zn, Au, Ag and Mn). It is found that the melting temperature is not linear with pressure and the slope [Formula: see text] of the melting curve decreases continuously with the increase in pressure. The results obtained with the present model are also compared with the previous theoretical and experimental data. A good agreement between theoretical and experimental result supports the validity of the present model.

Analysis of the Influence of Static Flow Resistance on the Sound Absorption Properties of Aluminum Foam

2012 ◽  
Vol 535-537 ◽  
pp. 1459-1462 ◽  
Author(s):  
Huai Qian Bao ◽  
Ning Zhang ◽  
Xue Gang Hou
Keyword(s):  
Sound Absorption ◽  
Flow Resistance ◽  
Aluminum Foam ◽  
Circular Tube ◽  
Peak Frequency ◽  
Absorption Properties ◽  
Absorption Frequency ◽  
Porous Aluminum ◽  
Static Flow ◽  
Resistance Value

For the complexity of the internal microstructure of porous aluminum foam, on the basis of Rayleigh-Kirchhoff circular tube model, taking viscosity loss and thermal transmission, the paper establishes a simplified theoretical model for sound absorption properties of aluminum foam. The paper also calculates and analyzes the influence of Static flow resistance on the sound absorption properties in the rigidity and cavity backing. The results show that the peak frequency moves to lower with the increasing of the thickness of the air layer. What’s more, there is a direct corresponding relation between flow resistance and the best sound absorption frequency range of aluminum foam. In a reasonable range of flow resistance value, the capability of sound absorption reach optimal, Aluminum Foam won’t have fine sound absorption capability if the value of flow resistance is too big or small.

scholarly journals Improving the Morphological Parameters of Aluminum Foam for Maximum Sound Absorption Coefficient using Genetic Algorithm

2021 ◽  
Vol 55 (2) ◽  
pp. 117-130
Author(s):  
Mohammad Javad Jafari ◽  
Mohsen Niknam Sharak ◽  
Ali Khavanin ◽  
Touraj Ebadzadeh ◽  
Mahmood Fazlali ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Aluminum Foam ◽  
Sound Absorption Coefficient ◽  
Morphological Parameters

Preparation and Sound Absorption Coefficient Test of Aluminum Foam with CaO Granules Infiltrating Agent

2018 ◽  
Vol 933 ◽  
pp. 55-60
Author(s):  
Yong Zhang ◽  
Zong Min Chen ◽  
Zhao Jun Wang ◽  
Jing Hui Liu
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Aluminum Foam ◽  
Low Frequency ◽  
Processing Parameters ◽  
Sound Absorption Coefficient ◽  
Pressure Infiltration ◽  
Pure Alcohol ◽  
Infiltration Pressure ◽  
High Sound

Three kinds of aluminum foam of different pore sizes were prepared with a tailor-made low-pressure infiltration device. CaO granules in three sizes (0.45~0.71mm,0.71~090mm and 1.25~1.60mm) were selected as infiltrating agents. The processing parameters were as follows: granules preheat temperature of 700 °C,infiltration pressure of 0.04 MPa and aluminum liquid temperature of 720 °C. In order to improve the removal performance and porosity, mixture of CaO powder of finer than 300 mesh and pure alcohol was mixed uniformly with granules, which made the slurry-coating granules conformal contacts rather than point contacts as in the traditional infiltration method. The testing results show that among all aluminum foam specimens tested with transfer function methods, two kinds have high sound absorption coefficient in low frequency (250~1600Hz).

Sound absorption of textile curtains – theoretical models and validations by experiments and simulations

2016 ◽  
Vol 88 (1) ◽  
pp. 36-48 ◽  
Author(s):  
Reto Pieren ◽  
Beat Schäffer ◽  
Stefan Schoenwald ◽  
Kurt Eggenschwiler
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Planning Process ◽  
Measurement Data ◽  
Theoretical Models ◽  
Sound Absorption Coefficient ◽  
Absorption Coefficients ◽  
Semi Empirical ◽  
Field Sound ◽  
Good Agreement

Textile curtains can be designed to be good sound absorbers. Their acoustical performance, as usually described by the sound absorption coefficient, not only depends on the textile itself but also on the drapery fullness and the backing condition, that is, the spacing between the fabric and a rigid backing wall, or the absence of a backing in the case of a freely hanging curtain. This article reviews existing models to predict the diffuse-field sound absorption coefficient, which to date can only predict the case of flat curtains. A set of existing models is extended to the case of curtains with drapery fullness using a semi-empirical approach. The models consider different backing conditions, including freely hanging curtains. The existing and new models are validated by comparing predicted sound absorption coefficients with data measured in a reverberation room. Hereby, curtains consisting of different fabrics and with different degrees of fullness are considered. Besides situations with rigid backing, also the measurement data of textiles hung freely in space are included in this study. Comparisons reveal a very good agreement between measured and predicted sound absorption coefficients. Compared to currently available commercial sound absorption prediction software that can only handle the situation of flat textiles with rigid backing, the results of the presented models not only show a better agreement with measured data, but also cover a broader range of situations. The presented models are thus well applicable in the design and development of new textiles as well as in the room acoustical planning process.

DIELECTRIC LOSSES IN ISOTENAX N

2003 ◽  
Vol 17 (07) ◽  
pp. 273-279 ◽  
Author(s):  
MIHAI RAZVAN MITROI ◽  
VLADIMIR IANCU ◽  
DOINA ELENA GAVRILA
Keyword(s):  
Experimental Data ◽  
Statistical Analysis ◽  
Composite Materials ◽  
Frequency Dependence ◽  
Dielectric Losses ◽  
Wagner Model ◽  
Improved Model ◽  
Good Agreement

The limits of the Maxwell–Wagner model for interfacial losses in composite materials are discussed. The model is improved by taking into account the frequency dependence of the loss resistances. The improved model is applied to the statistical analysis of the experimental data obtained on Isotenax N. The results of the model are in very good agreement with the experiment.

The role of hollow silica nanospheres and rigid silica nanoparticles on acoustic wave absorption of flexible polyurethane foam nanocomposites

2019 ◽  
Vol 56 (4) ◽  
pp. 395-410
Author(s):  
Zohreh Zangiabadi ◽  
Mohammad Jafar Hadianfard
Keyword(s):  
Absorption Coefficient ◽  
Silica Nanoparticles ◽  
Polyurethane Foam ◽  
Sound Wave ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Silica Nanospheres ◽  
Hollow Silica ◽  
The Matrix ◽  
Hollow Silica Nanospheres

Pure polyurethane foam and nanocomposite foam are used to absorb sound. In this study, hollow silica nanospheres and rigid silica nanoparticles were added to the polyurethane matrix and their sound absorption properties were investigated by impedance tube and compared with pure polyurethane foam. Reinforcement phase influences on the morphology of the matrix were studied by scanning electron microscopy. Due to greater effects of the rigid silica nanoparticles on the morphology of the matrix, it was expected to increase the sound absorption coefficient of the rigid silica nanoparticles/polyurethane, more than hollow silica nanospheres/polyurethane, but the results show that the hollow silica nanospheres increased absorption coefficient of the composite more efficiently. The crust of hollow silica nanospheres increases the number of boundaries in a sound wave, and the air gap inside them cause the sound wave to damp. So the intrinsic property of the hollow silica nanospheres is more effective than the matrix morphology. Thus, by the same content of reinforcement in the matrix, hollow silica nanosphere/polyurethane sample with sound absorption coefficient of 0.87 for a thickness of 9 cm has the highest sound absorption coefficient compared to the rigid silica nanoparticles/polyurethane sample and pure polyurethane foam. In pure and nanocomposite samples, sound absorption coefficient increased by increasing the thickness of samples.

scholarly journals Оптические свойства спироида C-=SUB=-300-=/SUB=-

2019 ◽  
Vol 89 (2) ◽  
pp. 169
Author(s):  
С.Г. Ястребов ◽  
М.С. Чекулаев ◽  
A. Siklitskaya
Keyword(s):  
Experimental Data ◽  
Matrix Element ◽  
Optical Absorption ◽  
Absorption Coefficient ◽  
Exchange Interaction ◽  
Optical Absorption Coefficient ◽  
Local Curvature ◽  
The Matrix ◽  
Strong Coupling Method ◽  
Good Agreement

AbstractCalculation results of the electronic spectrum of carbon nanospiroid C_300 are presented. The π-electron structure of the spiroid is calculated using the strong coupling method, in which the matrix element of the exchange interaction of neighboring electrons (the resonance integral) is considered as being dependent on the local curvature of the spiroid surface. The optical absorption coefficient is calculated in the framework of the Tautz model and the result is compared with experimental and astrophysical observational data. The calculated and experimental data are in good agreement.

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