Article
Engineering, Aerospace
Yiheng Guan, Sid Becker, Dan Zhao, Jingyuan Xu, Mohammad Shahsavari, Jorg Schluter
Summary: In this work, a 2D numerical model is developed to simulate a Y-shaped bifurcating combustor with a Helmholtz resonator. Propane is used as fuel and burnt with air. Experimental measurements validate the numerical findings, showing good agreement in frequency and amplitude of the dominant mode.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Acoustics
Leandro Rego, Francesco Avallone, Daniele Ragni, Damiano Casalino, Herve Denayer
Summary: A Helmholtz resonator with a curved cavity is studied for reducing jet-installation noise in a configuration comprised by a subsonic jet and a nearby flat plate. The results show that the resonators not only reduce the strength of the acoustic source, but also lower the sound pressure levels of the plate, achieving a noise reduction of approximately 7 dB at the resonance frequency of the single degree-of-freedom liner. The double degree-of-freedom resonator can further reduce the noise by about 3 dB at higher frequencies.
JOURNAL OF SOUND AND VIBRATION
(2022)
Article
Acoustics
Weiwei Wu, Yiheng Guan
Summary: This article investigated the performance of a modified Helmholtz resonator with a rigid baffle in terms of noise attenuation and frequency band widening. A numerical model was developed to evaluate the effects of different designs, and Design C was found to have better performance.
JOURNAL OF LOW FREQUENCY NOISE VIBRATION AND ACTIVE CONTROL
(2022)
Article
Acoustics
Zhiguo Zhang, Chenzhen Ji, Yin Mya Win
Summary: Helmholtz resonators are commonly used in industries to reduce unwanted noise transmission and attenuate tonal noise in pipes/ducts. However, a major drawback of conventional Helmholtz resonators is the narrow bandwidth. Different improved designs, such as array of resonators or mechanical-coupled resonators, have been proposed to broaden the effective noise damping frequency range. This review focuses on the aeroacoustics damping performance of coupled Helmholtz resonators over low frequency range, and discusses their transmission loss and sound absorption coefficient. Comparison is made between separately working resonators and mechanical-coupled ones, and the effect of mean grazing flow is examined. A case study and brief overview of neck design and numerical simulation approaches are included.
JOURNAL OF LOW FREQUENCY NOISE VIBRATION AND ACTIVE CONTROL
(2023)
Article
Acoustics
J. Dandsena, D. P. Jena
Summary: This research demonstrates a significant improvement in the bandwidth of interest by installing porous material in the cavity of periodic Helmholtz resonators. The peak amplitude of transmission loss at the resonance frequency regime is damped and impractical when the porous material is installed inside a single resonator. However, with an array of resonators having porous cores, the observed transmission loss has the desired amplitude and elevated bandwidth, making it practical.
Article
Acoustics
Weiwei Wu, Yiheng Guan
Summary: This study focuses on maximizing the noise damping performance of resonators by optimizing and applying extended neck designs, showing that extended neck designs can achieve higher transmission loss performance over a broader frequency range.
JOURNAL OF LOW FREQUENCY NOISE VIBRATION AND ACTIVE CONTROL
(2021)
Article
Multidisciplinary Sciences
Shuping Wang, Jiancheng Tao, Xiaojun Qiu, Ian S. Burnett
Summary: This study found that staggered windows outperform traditional single-glazed windows in noise reduction at mid to high frequencies while allowing for natural ventilation. To achieve noise attenuation in the low frequency range, a novel coiled-up silencer design with coupled tubes is proposed, showing improved noise reduction capability across a wider spectrum.
SCIENTIFIC REPORTS
(2021)
Article
Acoustics
Ahmad Yusuf Ismail, Jisan Kim, Se-Myong Chang, Bonyong Koo
Summary: This paper presents a study on the impact of Helmholtz resonator-based acoustic metasurface on sound transmission loss. By optimizing the design variables of the metasurface, such as the number of cells, thickness, and multilayering, the noise reduction performance of the system can be improved. Experimental validation and numerical results demonstrate the effectiveness of the proposed design.
Article
Engineering, Aerospace
Hadi Dastourani, Iman Bahman-Jahromi
Summary: This study investigates the impact of resonator cavity shape on the aeroacoustic performance of a Helmholtz resonator system. By utilizing a three-dimensional numerical approach and considering various Mach numbers, it was found that changing the resonator cavity shape can significantly affect the acoustic performance, with variations in resonant frequency and peak transmission loss. Spheres and cylinders were shown to have better performance compared to other considered cavity shapes.
JOURNAL OF AEROSPACE ENGINEERING
(2021)
Article
Acoustics
Charlie Bricault, Yang Meng, Sebastien Goude
Summary: In this work, a general design strategy for passive acoustic treatments dealing with low frequency, broadband noise is proposed. The design involves the use of arrays of Helmholtz resonators along the walls of a rectangular waveguide. An analytical model based on the transfer matrix method is used to relate the resonator parameters and acoustic response of the system. Optimization is carried out to find the optimal structural design that minimizes the transmission coefficient in the desired frequency range. Two specific designs are provided and their acoustic performances are validated through simulations and measurements. The proposed design method can be easily applied to waveguides with different cross-sectional shapes and has broad applications in engineering projects involving noise reduction in HVAC systems.
Article
Acoustics
Pyung-Sik Ma, Hyun-Sil Kim, Seong-Hyun Lee, Ji-Wan Kim
Summary: This paper studies the improvement of sound transmission loss (STL) in a finite plate by attaching a slit-type Helmholtz resonator or a slit resonator. The resonant frequency of the slit resonator is tuned to enhance the poor STL at the dip corresponding to the first natural frequency of the plate. Analytical derivations are used to determine the STL of the slit resonator, plate, and the combined structure. The effects of slit geometry and cavity size on the resonance frequency are explained using an equivalent circular neck of a Helmholtz resonator. The proposed method is validated through experimental results, showing good agreement.
Article
Acoustics
Rong Xue, Cheuk Ming Mak, Dizi Wu, Kuen Wai Ma
Summary: This study investigated the influence of neck length, cavity volume, and flow Mach number on the noise attenuation performance of a dual Helmholtz resonators (HR) system. The results showed that the second neck length affected the second resonance frequency and maximum transmission loss (TL). Changing the cavity volume had a significant impact on noise attenuation ability at lower flow rates. The flow Mach number had a more pronounced effect on the first TL peak than the second TL peak. This study provides guidance in designing suitable dual HRs for aero-engine systems.
INTERNATIONAL JOURNAL OF AEROACOUSTICS
(2023)
Article
Instruments & Instrumentation
Lei Han, Hongli Ji, Jinhao Qiu
Summary: This paper proposes a modified theory for synthesizing the acoustic impedance of an absorbing panel by considering the interference among parallel absorbers. The results of validation on different absorbing panels and the comparison with the mutual-radiation-impedance method show that the modified theoretical model is better at predicting the absorption coefficient than is the traditional theory.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Acoustics
F. Langfeldt, A. J. Khatokar, W. Gleine
Summary: This paper investigates a new approach for improving the bandwidth of plate-type acoustic metamaterials (PAM) by using Helmholtz resonators. By adding Helmholtz resonators to PAM, the bandwidth of sound transmission loss can be increased without significant reductions in sound transmission loss.
Article
Thermodynamics
Hiroshi Yokoyama, Yasuaki Omori, Masashi Kume, Masahito Nishikawara, Hideki Yanada
Summary: This research investigated the flow conditions for an effective thermoacoustic heat pump driven by acoustic radiation in cavity flows. Computational simulations were conducted to analyze the coupled phenomena between fluid and acoustic interactions as well as heat conduction in the flat plates installed in the cavity. The results showed that the installation of the stack reduced sound pressure levels and power of velocity fluctuations compared to the cavity flow without a stack. The computational method used in this study is expected to be valuable for exploring the utilization of aerodynamical sound energy for heat energy conversion.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Engineering, Aerospace
Andre F. P. Ribeiro, Carlos Ferreira, Damiano Casalino
Summary: This study compares a filament-based free wake panel method to experimental and validated numerical data in order to simulate propeller slipstreams and their interaction with aircraft components. The results show that the free wake panel method is able to successfully capture the slipstream deformation and shearing, making it a useful tool for propeller-wing interaction in preliminary aircraft design.
AEROSPACE SCIENCE AND TECHNOLOGY
(2024)