scholarly journals Influence of Sugar Palm Ash Fraction and Resonator Configuration on Acoustic Absorption Performance of Expose Brick

2016 ◽  
Vol 4 (01) ◽  
pp. 19
Author(s):  
Zulfa Kamila R ◽  
Iwan Yahya ◽  
Utari U
Keyword(s):  
Performance Improvement ◽  
Performance Optimization ◽  
Sound Absorption ◽  
Low Frequency ◽  
Helmholtz Resonator ◽  
Raw Material ◽  
Frequency Range ◽  
Helmholtz Resonators ◽  
Resonator Structure ◽  
Absorption Performance

<span>Sound absorption performance optimization of expose brick has been conducted in associated with <span>the fraction of sugar palm ash in its raw material and configuration of Helmholtz resonators inside <span>the brick structure. The testing was conducted experimentally refer to ASTM E-1050-98 standard <span>procedure. In this case there are three variations sugar palm ash fractions of 0%, 5%, and 10%, as <span>well as two array resonator configurations. The results showed that the brick with fraction of 10% <span>sugar palm ash has the best sound absorption performance. As for the configuration of array <span>identical Helmholtz resonator giving better performance improvement at low frequency span than <span>complex resonator structure with coupled cavity where the best performance occur on(376-488) <span>Hz frequency range with the absorption coefficient α of 0.54.</span></span></span></span></span></span></span></span><br /></span>

scholarly journals Numerical investigation on low-frequency noise damping performances of Helmholtz resonators with an extended neck in presence of a grazing flow

2021 ◽  
pp. 146134842110205
Author(s):  
Weiwei Wu ◽  
Yiheng Guan
Keyword(s):  
Resonant Frequency ◽  
Stokes Equations ◽  
Transmission Loss ◽  
Low Frequency ◽  
Helmholtz Resonator ◽  
Frequency Noise ◽  
Frequency Range ◽  
Helmholtz Resonators ◽  
Numerical Predictions ◽  
Grazing Flow

In this work, modified designs of Helmholtz resonators with extended deflected neck are proposed, numerically evaluated and optimized aiming to achieve a better transmission loss performance over a broader frequency range. For this, 10 Helmholtz resonators with different extended neck configurations (e.g. the angle between extended neck and the y-axis) in the presence of a grazing flow are assessed. Comparison is then made between the proposed resonators and the conventional one, i.e. in the absence of an extended neck (i.e. Design A). For this, a two-dimensional linearized Navier Stokes equations-based model of a duct with the modified Helmholtz resonator implemented was developed in frequency domain. The model was first validated by comparing its numerical predictions with the experimental results available in the literature and the theoretical results. The model was then applied to evaluate the noise damping performance of the Helmholtz resonator with (1) an extended neck on the upstream side (Design B); (2) on the downstream side (Design C), (3) both upstream and downstream sides (Design D), (4) the angle between the extended neck and the y-axis, i.e. (a) 0°, (b) 30°, and (c) 45°, (d) 48.321°. In addition, the effects of the grazing flow Mach number (Ma) were evaluated. It was found that the transmission loss peaks of the Helmholtz resonator with the extended neck was maximized at Ma = 0.03 than at the other Mach numbers. Conventional resonator, i.e. Design A was observed to be associated with a lower transmission loss performance at a lower resonant frequency than those as observed on Designs B–D. Moreover, the optimum design of the proposed resonators with the extended neck is shown to be able to shift the resonant frequency by approximately 90 Hz, and maximum transmission loss could be increased by 28–30 dB. In addition, the resonators with extended necks are found to be associated with two or three transmission loss peaks, indicating that these designs have a broader effective frequency range. Finally, the neck deflection angles of 30° and 45° are shown to be involved with better transmission loss peaks than that with a deflection angle of 0°. In summary, the present study sheds light on maximizing the resonator’s noise damping performances by applying and optimizing an extended neck.

scholarly journals Modifikasi Permukaan Elemen Peredam Bising Dengan Profil Berbentuk Prisma

2016 ◽  
Vol 6 (01) ◽  
Author(s):  
Hanif Azimut
Keyword(s):  
High Frequency ◽  
Sound Absorption ◽  
Coupling Effect ◽  
Low Frequency ◽  
The Other ◽  
Frequency Range ◽  
Closed Type ◽  
Wave Resonance ◽  
Half Wave ◽  
Absorption Performance

<p class="AbstractText">The influence of surface modification by using prism shaped profile on the sound absorption of absorber element was investigated experimentally. A prime number based configuration of the two types opened and closed type rism shaped profile inclusion was tested by using impedance tube according ASTM E1050 standard. The result shows that sound absorption at low frequency band below 200 Hz increased with the increasing of closed prism number. It is related to the coupling effect between the cavities of the absorber element and the prisms that changes reactance of the coupled structure. In the other side, a half wave resonance like effect occur on the use of opened prisms inclusion, which is increase the sound absorption performance at mid to high frequency range between 800 Hz to 1,25 kHz.  </p>

scholarly journals Modifikasi Permukaan Elemen Peredam Bising dengan Profil Berbentuk Prisma

2016 ◽  
Vol 6 (01) ◽  
pp. 23
Author(s):  
Julius Indra Kusuma ◽  
H Harjana ◽  
Iwan Yahya
Keyword(s):  
High Frequency ◽  
Sound Absorption ◽  
Coupling Effect ◽  
Low Frequency ◽  
The Other ◽  
Frequency Range ◽  
Closed Type ◽  
Wave Resonance ◽  
Half Wave ◽  
Absorption Performance

The influence of surface modification by using prism shaped profile on the sound absorption of absorber element was investigated experimentally. A prime number based configuration of the two types opened and closed type rism shaped profile inclusion was tested by using impedance tube according ASTM E1050 standard. The result shows that sound absorption at low frequency band below 200 Hz increased with the increasing of closed prism number. It is related to the coupling effect between the cavities of the absorber element and the prisms that changes reactance of the coupled structure. In the other side, a half wave resonance like effect occur on the use of opened prisms inclusion, which is increase the sound absorption performance at mid to high frequency range between 800 Hz to 1.25 kHz.

scholarly journals Diffuse Sound Absorptive Properties of Parallel-Arranged Perforated Plates with Extended Tubes and Porous Materials

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1091 ◽  
Author(s):  
Dengke Li ◽  
Daoqing Chang ◽  
Bilong Liu
Keyword(s):  
Boundary Condition ◽  
Porous Material ◽  
Porous Materials ◽  
Sound Absorption ◽  
Azimuthal Angle ◽  
Octave Band ◽  
Frequency Range ◽  
Absorption Coefficients ◽  
Perforated Plates ◽  
Absorption Performance

The diffuse sound absorption was investigated theoretically and experimentally for a periodically arranged sound absorber composed of perforated plates with extended tubes (PPETs) and porous materials. The calculation formulae related to the boundary condition are derived for the periodic absorbers, and then the equations are solved numerically. The influences of the incidence and azimuthal angle, and the period of absorber arrangement are investigated on the sound absorption. The sound-absorption coefficients are tested in a standard reverberation room for a periodic absorber composed of units of three parallel-arranged PPETs and porous material. The measured 1/3-octave band sound-absorption coefficients agree well with the theoretical prediction. Both theoretical and measured results suggest that the periodic PPET absorbers have good sound-absorption performance in the low- to mid-frequency range in diffuse field.

Numerical study for increasement of low frequency sound insulation of double-panel structure using sonic crystals with distributed Helmholtz resonators

2019 ◽  
Vol 33 (14) ◽  
pp. 1950138
Author(s):  
Myong-Jin Kim
Keyword(s):  
Free Space ◽  
Transmission Loss ◽  
Numerical Study ◽  
Low Frequency ◽  
Helmholtz Resonator ◽  
Sound Insulation ◽  
The Finite Element Method ◽  
Helmholtz Resonators ◽  
Sonic Crystal ◽  
Sonic Crystals

Numerical simulations of the sound transmission loss (STL) of a double-panel structure (DPS) with sonic crystal (SC) comprised of distributed local resonators are presented. The Local Resonant Sonic Crystal (LRSC) consists of “C”-shaped Helmholtz resonator columns with different resonant frequencies. The finite element method is used to calculate the STL of such a DPS. First, the STLs of LRSC in free space and the DPS with LRSC are calculated and compared. It is shown that the sound insulations of the local resonators inserted in the double panel are higher than that in free space for the same size of the SCs and the same number of columns. Next, STL of the DPS in which the SC composed of three columns of local resonators having the same outer and inner diameters but different slot widths are calculated, and a reasonable arrangement order is determined. Finally, the soundproofing performances of DPS with distributed LRSC are compared with the case of insertion of general cylindrical SC for SC embedded in glass wool and not. The results show that the sound insulation of the DPS can be significantly improved in the low frequency range while reducing the total mass without increasing the thickness.

Broadening of the Sound Absorption Bandwidth of the Perforated Panel Using a Membrane-Type Resonator

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Xuezhi Zhu ◽  
Zhaobo Chen ◽  
Yinghou Jiao ◽  
Yanpeng Wang
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Degrees Of Freedom ◽  
Low Frequency ◽  
Absorption Capacity ◽  
Sound Absorption Coefficient ◽  
Sound Waves ◽  
Frequency Range ◽  
Absorption Bandwidth ◽  
Membrane Type

In order to broaden the sound absorption bandwidth of a perforated panel in the low frequency range, a lightweight membrane-type resonator is installed in the back cavity of the perforated panel to combine into a compound sound absorber (CSA). Because of the great flexibility, the membrane-type resonator can be vibrated easily by the incident sound waves passing through the holes of the perforated panel. In the low frequency range, the membrane-type resonator and the perforated panel constitute a two degrees-of-freedom (DOF)-resonant type sound absorption system, which generates two sound absorption peaks. By tuning the parameters of the membrane type resonator, a wide frequency band having a large sound absorption coefficient can be obtained. In this paper, the sound absorption coefficient of CSA is derived analytically by combining the vibration equation of the membrane-type resonator with the acoustic impedance equation of the perforated panel. The influences of the parameters of the membrane-type resonator on the sound absorption performance of the CSA are numerically analyzed. Finally, the wide band sound absorption capacity of the CSA is validated by the experimental test.

Analysis of Sound Absorption Properties of Three-Leaf Microperforated Panel Absorbers without a Rigid Backing

2014 ◽  
Vol 937 ◽  
pp. 465-471
Author(s):  
Xiao Ling Gai ◽  
Xian Hui Li ◽  
Rui Wu ◽  
Bin Zhang ◽  
Jun Juan Zhao
Keyword(s):  
Sound Absorption ◽  
Low Frequency ◽  
Wide Frequency Range ◽  
Structure Design ◽  
Frequency Region ◽  
Theoretical Development ◽  
Frequency Range ◽  
Absorption Properties ◽  
High Frequency Region ◽  
Energy Dissipated

Microperforated panel (MPP) absorbers have been developed rapidly and used in many fields in recent years. First, based on the Maa’s theory, the theoretical development of MPP is reviewed in this paper. Furthermore, structure design and processing technology of MPP are introduced. Finally, the further development of MPP is discussed. Based on the MPP theory and electro-acoustical equivalent circuit principle, sound absorption properties of three-leaf microperforated panel (TMPP) absorbers without a rigid backing are studied to broaden the sound absorption bandwidth of MPP structure. Simulation results show that TMPP absorbers without a rigid backing have two resonance peaks and the energy dissipated coefficient remains constant in the low frequency range. The resonance frequency moves toward low frequency region with the increasing of the distance, thickness and pore diameter of MPP and moves toward high frequency region with the increasing of the perforation when other parameters keep invariant. The energy dissipated coefficient more than 0.5 over 8 octaves by choosing proper parameters. In conclusion, TMPP absorbers without a rigid backing have good sound absorption properties in a wide frequency range.

scholarly journals High-Temperature and Low-Frequency Acoustic Energy Absorption by a Novel Porous Metamaterial Structure

2021 ◽  
Author(s):  
Qihang Liu ◽  
Xuewei Liu ◽  
Chuanzeng Zhang ◽  
Fengxian Xin
Keyword(s):  
High Temperature ◽  
Theoretical Model ◽  
Porous Material ◽  
Energy Absorption ◽  
Low Frequency ◽  
Acoustic Energy ◽  
Frequency Range ◽  
Metamaterial Structure ◽  
Equivalent Inclusion ◽  
Absorption Performance

AbstractIn this paper, we propose a novel porous metamaterial structure with an improved acoustic energy absorption performance at high-temperature and in the low-frequency range. In the proposed novel porous metamaterial structure, a porous material matrix containing periodically perforated cylindrical holes arranged in a triangular lattice pattern is applied, and additional interlayers of another porous material are introduced around these perforations. The theoretical model is established by adopting the double porosity theory for the interlayer and the cylindrical hole which form an equivalent inclusion and then applying the homogenization method to the porous metamaterial structure formed by the equivalent inclusion and the porous matrix. The temperature-dependent air and material parameters are considered in the extended theoretical model, which is validated by the finite element results obtained by COMSOL Multiphysics. The acoustic or sound energy absorption performance can be improved remarkably at very low frequencies and high temperature. Furthermore, the underlying acoustic energy absorption mechanism inside the unit-cell is investigated by analyzing the distribution of the time-averaged acoustic power dissipation density and the energy dissipation ratio of each constituent porous material. The results reveal that regardless of the temperature, the acoustic energy is mostly dissipated in the porous material with a lower airflow resistivity, while the acoustic energy dissipated in the porous material with a higher airflow resistivity also becomes considerable in the high-frequency range. The novel porous metamaterial structure proposed in this paper can be efficiently utilized to improve the acoustic energy absorption performance at high temperature.

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