scholarly journals Numerical and Experimental Analysis of Sound Suppressor for a 5.56 mm Calibre

2021 ◽  
Vol 71 (1) ◽  
pp. 12-17
Author(s):  
J. K. Huerta-Torres ◽  
U. S. Silva-Rivera ◽  
V. F. Verduzco-Cedeño ◽  
L. A. Flores-Herrera ◽  
J. M. Sandoval-Pineda
Keyword(s):  
Numerical Simulation ◽  
Acoustic Wave ◽  
Experimental Analysis ◽  
Sound Pressure ◽  
Pressure Level ◽  
Dissipative Systems ◽  
External Device ◽  
Negative Effects ◽  
Average Value ◽  
Geometric Configurations

A sound suppressor is an internal or external device coupled to the barrel of a firearm. Its development has been historically related to the negative effects produced by the noise. This article presents the numerical and experimental analysis of a sound suppressor for a 5.56 mm caliber rifle. It was designed, manufactured, and tested inside a shooting tunnel for 911 m/s and 344 m/s velocities. Three geometric configurations with curved deflectors, conical deflectors, and finally with a reactive spiral capable of dissipating the acoustic wave were compared considering reactive and dissipative systems. The attenuation of the sound inside the silencer depends directly on the reduction of the projectile wave velocity and the deflagration of the gases at the instant of firing. Then the MIL-STD-1474E standard was used to carry out the experiments. The results in the computational numerical simulation show an average value of 143 dB for the considered three models, the Sound Pressure Level in the reactive core model decreased by 25% with respect to other proposals, which have an average value of 141 dB. These results can be useful to improve in the design of sound suppressors based on the needs of the users and under the specific characteristics of each weapon ballistic. 

Thickness-resonance waves in underlays of floating screed

2021 ◽  
Vol 263 (3) ◽  
pp. 2973-2983
Author(s):  
Charlotte Crispin ◽  
Debby Wuyts ◽  
Dijckmans Arne
Keyword(s):  
Finite Element ◽  
Transfer Matrix ◽  
Sound Pressure Level ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Sound Pressure ◽  
Pressure Level ◽  
Experimental Results ◽  
Simplified Model ◽  
Negative Effects

The prediction of the reduction of impact sound pressure level ΔL according to annex C of the standard ISO 12354-2 gives an acceptable estimation of the floating floor's performance for thin resilient layers. However, the performance is often largely overestimated for thick resilient layers or for resilient layers combined with thermal layers. One reason for this is that the simplified model doesn't account for the thickness resonances in the underlays which can greatly affect ΔL. This is confirmed by comparing finite element and transfer matrix method simulations with experimental results. This paper establishes the mechanisms leading to the development of these resonance waves and provides some guidelines to estimate their negative effects on the ΔL.

scholarly journals FEATURES OF TRAFFIC NOISE ASSESSMENT AT ROUNDABOUTS IN IZHEVSK

2020 ◽  
Vol 30 (1) ◽  
pp. 37-42
Author(s):  
S.A. Gagarin ◽  
O.V. Gagarina ◽  
Omar Hazza Al-Subari
Keyword(s):  
Acoustic Wave ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Traffic Noise ◽  
Pressure Level ◽  
Time Range ◽  
Acoustic Measurements ◽  
Traffic Lights ◽  
Noise Assessment ◽  
Simulation Results

The conditions of acoustic wave formation under urban development within traffic roundabouts are considered on the example of Izhevsk. The article refers to 5 single-level road interchanges, and provides the results of multiple acoustic measurements of the equivalent sound pressure level. The observations covered a different time range, typical for the daytime period. The average values vary from 66 to 68 dBA, and the maximum values range from 67 to 69 dBA. Based on the simulation results, acoustic discomfort zones were determined for each interchange. The variation was from 50 to 75 meters at averaged values of flows intensity (up to 1500 u / h) and from 60 to 110 meters at high intensity (up to 2000 u / h). The conclusion is made about the favorability of roundabouts from the position of noise comfort in comparison with traditional intersections equipped with traffic lights. The effectiveness of such measures is 2-3 dB.

DETERMINATION OF MONOPOLE AND DIPOLE SOURCES OF FLOW AROUND A CYLINDER USING A VIRTUAL MICROPHONE ARRAY

Akustika ◽  
2021 ◽  
pp. 76
Author(s):  
Victor Ershov ◽  
Igor Khramtsov ◽  
Oleg Kustov
Keyword(s):  
Numerical Simulation ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Microphone Array ◽  
Pressure Level ◽  
Noise Sources ◽  
Ansys Fluent ◽  
Flow Around A Cylinder ◽  
Vortex Shedding Frequency

In this paper, the problem of localization of noise sources of flow around a cylinder was considered on the basis of a computational experiment using a virtual 54-channel microphone array. Numerical simulation was performed using the computational fluid dynamics software ANSYS Fluent. Several spatial orientations of the cylinder were considered for the generation of dipoles with different directions. Simulation of a simplified two-microphone azimuthal decomposition technique (ADT) is performed to determine the sound pressure level of the generated dipoles at a vortex shedding frequency of 1450 Hz. A procedure of localization of the noise of the flow around a virtual cylinder was performed using monopole and dipole beamforming algorithms. It was found that the numerical simulation results are in good agreement with the data obtained by other researchers, both in terms of the sound pressure level and the results of the localization of dipoles in space.

Numerical Simulation Research of Butterfly Valve in Acoustics Field Variation Characteristics

2017 ◽  
Vol 872 ◽  
pp. 217-222
Author(s):  
Hai Jiao Wei ◽  
Guo Fang Wu ◽  
Fu Hong Zhang ◽  
Jiao Xue ◽  
Kun Sheng Zhou ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Pressure Level ◽  
Opening Angle ◽  
Field Variation ◽  
Butterfly Valve ◽  
Simulation Research ◽  
Excited Vibration ◽  
Opening Process

A numerical simulation research was carried out on vortex and sound pressure level of the butterfly valve in the flow process based on FLUENT, which analyzed the variation of the vorticity and sound pressure level at different opening angles. There was an inverse pressure gradient in the orifice formed by the butterfly plate and pipe, which caused partial particle reflux on the back of butterfly plate in flowing, thus formed the vortex. The vortex formed on the back of the butterfly plate was decreased gradually, with the increasing opening angle of the valve in opening process. The noise was generated by the vortex separated and rupture in flowing. And the sound pressure level on the back of butterfly plate was decreased with the increasing opening angle. At the same time, the vorticity and the maximum sound pressure level position moved from the center to the rotation center of butterfly plate in opening process. The expanding orifice formed by butterfly plate upstream and the pipe and the tapered orifice formed by butterfly plate downstream and the pipe had the different throttling action to the fluid, which made the sound pressure level of upstream was higher than that of downstream in symmetrical position. The vortex generated by the separation of boundary layer would cause vortex excited vibration between plate and fluid, and then resonance occurred. The studies were carried out in the vorticity and the sound pressure level on the downstream of butterfly plate, and the changing law of those was found. It would provide a basis theory for reducing noise and avoiding vortex vibration of butterfly valve.

Vibration Characteristics of Ni Thin Film Diaphragm by Acoustic Wave

2010 ◽  
Vol 97-101 ◽  
pp. 2361-2364
Author(s):  
Gue Serb Cho ◽  
Won Sik Lee ◽  
Se Hyun Ko ◽  
Seong Ho Son ◽  
Chang Woo Lee ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Natural Frequency ◽  
Sound Pressure ◽  
Pressure Level ◽  
Resonance Mode ◽  
Vibration Characteristics ◽  
Unit Size ◽  
Frequency Range ◽  
Increase With Increase ◽  
Out Of Plane

Vibration characteristics of 5μm- thick Ni film were investigated with applying acoustic wave to the Ni diaphragm of 2mm x 2mm unit size. In the modal analysis, the first resonance mode of the diaphragm showed an out-of-plane piston-like movement and the first natural frequency was 1,643 Hz, whereas in this experiment, the first natural frequency appears at about 1,300 Hz under sound pressure of 0.2 Pa. The amplitudes of diaphragm increase with increase of sound pressure level in the applied frequency range from 300 Hz to 1,000 Hz, indicating that area of diaphragm influences directly the amplitude.

scholarly journals Study on acoustic source characteristics of distributed optical fiber acoustic wave monitoring buried natural gas pipeline leakage

2021 ◽  
Vol 252 ◽  
pp. 03043
Author(s):  
Chun Wang ◽  
Zan Wang ◽  
Jia Zhang ◽  
Kelong Yang
Keyword(s):  
Natural Gas ◽  
Acoustic Wave ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Low Frequency ◽  
Pressure Level ◽  
Gas Pipeline ◽  
Sound Waves ◽  
Natural Gas Pipeline ◽  
Distributed Optical Fiber

In order to study the leakage of buried natural gas pipeline caused serious environmental pollution and human casualties, the acoustic propagation characteristics of buried natural gas pipeline leakage monitored by distributed optical fiber were studied. At present, the research on the leakage of buried pipeline mainly focuses on the propagation of sound waves along the pipe wall, while the study on the propagation of sound waves in the soil is still lacking. The acoustic attenuation of acoustic wave propagation in soil by the size of leakage hole and leakage pressure is studied, and the evolution process of acoustic wave in soil is revealed. The conclusion is that the acoustic source of buried natural gas pipeline leakage belongs to broadband noise, and the acoustic energy of leakage is prominent in the low frequency band of 15kHz. The lower frequency, the higher sound pressure level. The oscillation of the sound pressure level attenuates with the increase of frequency. Fiber optic monitoring of buried natural gas pipeline leakage early warning provides theoretical support for the conclusion. The sound pressure level in low frequency band is of great significance for buried pipeline leakage monitoring.

Contributions of Voice and Nonverbal Communication to Perceived Masculinity–Femininity for Cisgender and Transgender Communicators

2020 ◽  
Vol 63 (4) ◽  
pp. 931-947
Author(s):  
Teresa L. D. Hardy ◽  
Carol A. Boliek ◽  
Daniel Aalto ◽  
Justin Lewicke ◽  
Kristopher Wells ◽  
...  
Keyword(s):  
Fundamental Frequency ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Vocal Tract ◽  
Presentation Mode ◽  
Pressure Level ◽  
Presentation Modes ◽  
Audiovisual Stimuli ◽  
Vocal Tract Resonance ◽  
Point Light

Purpose The purpose of this study was twofold: (a) to identify a set of communication-based predictors (including both acoustic and gestural variables) of masculinity–femininity ratings and (b) to explore differences in ratings between audio and audiovisual presentation modes for transgender and cisgender communicators. Method The voices and gestures of a group of cisgender men and women ( n = 10 of each) and transgender women ( n = 20) communicators were recorded while they recounted the story of a cartoon using acoustic and motion capture recording systems. A total of 17 acoustic and gestural variables were measured from these recordings. A group of observers ( n = 20) rated each communicator's masculinity–femininity based on 30- to 45-s samples of the cartoon description presented in three modes: audio, visual, and audio visual. Visual and audiovisual stimuli contained point light displays standardized for size. Ratings were made using a direct magnitude estimation scale without modulus. Communication-based predictors of masculinity–femininity ratings were identified using multiple regression, and analysis of variance was used to determine the effect of presentation mode on perceptual ratings. Results Fundamental frequency, average vowel formant, and sound pressure level were identified as significant predictors of masculinity–femininity ratings for these communicators. Communicators were rated significantly more feminine in the audio than the audiovisual mode and unreliably in the visual-only mode. Conclusions Both study purposes were met. Results support continued emphasis on fundamental frequency and vocal tract resonance in voice and communication modification training with transgender individuals and provide evidence for the potential benefit of modifying sound pressure level, especially when a masculine presentation is desired.

Influence of the Acoustic Reflex on Vowel Recognition

1986 ◽  
Vol 29 (3) ◽  
pp. 420-424 ◽  
Author(s):  
Michael Dorman ◽  
Ingrid Cedar ◽  
Maureen Hannley ◽  
Marjorie Leek ◽  
Julie Mapes Lindholm
Keyword(s):  
Auditory System ◽  
Sound Pressure ◽  
Dynamic Range ◽  
Recognition Accuracy ◽  
Pressure Level ◽  
Acoustic Reflex ◽  
The Poor ◽  
Stapedial Reflex ◽  
Vowel Recognition ◽  
High Sound

Computer synthesized vowels of 50- and 300-ms duration were presented to normal-hearing listeners at a moderate and high sound pressure level (SPL). Presentation at the high SPL resulted in poor recognition accuracy for vowels of a duration (50 ms) shorter than the latency of the acoustic stapedial reflex. Presentation level had no effect on recognition accuracy for vowels of sufficient duration (300 ms) to elicit the reflex. The poor recognition accuracy for the brief, high intensity vowels was significantly improved when the reflex was preactivated. These results demonstrate the importance of the acoustic reflex in extending the dynamic range of the auditory system for speech recognition.

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