Experimental investigation of the influence of the outflow parameters of two-duct, nonisothermal jets on the level of sound pressure and the frequency spectrum of emitted noise

1990 ◽  
Vol 58 (4) ◽  
pp. 393-398
Author(s):  
S. Yu. Krasheninnikov ◽  
M. N. Tolstosheev
Keyword(s):  
Experimental Investigation ◽  
Frequency Spectrum ◽  
Sound Pressure ◽  
Level Of Sound Pressure

scholarly journals The Effect of Frequency Acoustic Stimulation Sound on Intrauterine Weakening of Pregnant Sheep

2017 ◽  
Vol 3 (6) ◽  
pp. 125
Author(s):  
Djamil Suherman ◽  
Hermanto Tri Joewono ◽  
I Komang Wiarsa Sardjana
Keyword(s):  
Abdominal Wall ◽  
Sound Pressure ◽  
Acoustic Stimulation ◽  
Uterine Wall ◽  
Sound Frequency ◽  
Pregnant Sheep ◽  
Post Test ◽  
The Difference ◽  
Level Of Sound Pressure ◽  
Veterinary Faculty

Research to determine changes in intrauterine sound pressure in pregnant sheep after administration acoustic stimulation outside of the abdominal wall at some frequency sounds. The study was conducted at the Animal Hospital of Veterinary Faculty of Airlangga University. Pre test experimental design with pre- and post-test one group to assess intra-uterine sound pressure changes. The study was conducted at two lambs pregnant aterm after acoustic stimulation at a distance of 10 cm from the surface of the abdominal wall to the sound pressure 80,85,90,95 and 100 decibels and sound frequency of 31.5, 63, 125, 250, 500, 1000, 2000, 4000, 6000 and 8000 hertz. The results showed that the difference between the sound pressure outside of the abdominal wall with intrauterine sound pressure on both the pregnant sheep by an average of 16.7570 ± 8.0797 decibels. This shows their weakening sound after passing through the abdominal wall and the uterine wall. By using a paired t-test, this weakening statistically significant. At frequencies from 31.5 to 1000 hertz weakening values from 5.2 to 17.1 decibels while in 2000-8000 hertz frequency weakening value of 20.2 to 30.8 decibels. The conclusion that the stimulation of noise from outside the walls of the abdomen weakening sound after penetrating the abdominal wall and the uterine wall. Weakening occur at every level of sound pressure and at every level of a given frequency. Weakening value becomes greater at frequencies above 1000 hertz.                                                                                                       Keywords: weakening, sound pressure, sound frequency, pregnant sheep.

Spectrum Analysis of Infrasound Signal

2014 ◽  
Vol 644-650 ◽  
pp. 4334-4337
Author(s):  
Bin Wang
Keyword(s):  
Frequency Spectrum ◽  
Frequency Distribution ◽  
Spectrum Analysis ◽  
Sound Pressure ◽  
Power Level ◽  
Amplitude Spectrum ◽  
Frequency Component ◽  
Pressure Amplitude ◽  
Frequency Spectrum Analysis ◽  
Infrasound Signal

In this paper, frequency spectrum of infrasound signal collected was analyzed based on MATLAB. The infrasound power level of change with frequency distribution and the infrasound harmonic of each frequency component of the sound pressure amplitude can be made up judgment visually by frequency spectrum analysis and amplitude spectrum analysis, and thus we can obtain different conditions of infrasound properties scientifically and quantitatively.

scholarly journals EXPERIMENTAL INVESTIGATION OF ACOUSTIC FIELD INFLUENCE FOR AEROSOLS PARTICLES / AKUSTINIO LAUKO ĮTAKOS AEROZOLIO DALELIŲ KOAGULIACIJAI EKSPERIMENTINIAI TYRIMAI

2016 ◽  
Vol 7 (6) ◽  
pp. 609-612
Author(s):  
Ina Tetsman ◽  
Irina Grinbergienė
Keyword(s):  
Experimental Investigation ◽  
Acoustic Field ◽  
Sound Pressure ◽  
Particle Diameter ◽  
Particle Coagulation ◽  
Experimental Stand ◽  
Coagulation Of Particles ◽  
Field Excitation ◽  
Field Sound ◽  
Field Influence

There were made tests of particulate matter (aerosol), of coagula-tion efficiency, depending on the acoustic field sound pressure and frequency. It is described experimental stand that is used to do researches and methodology of experiments performance. It is used two sound generators for acoustic field excitation: piezoe-lectric and aero-acoustic. It was determined after researches, that increasing the frequency of the acoustic field, it is increased rate of particle coagulation when particle diameter not greater than 1 μm. Effectively coagulation of particles up to 1 μm in diameter must subsonic acoustic field frequencies, as the particles over 1 μm in diameter must be lower than the frequency of ultrasonic acoustic field. Atlikti labai mažo skersmens kietųjų dalelių koaguliacijos efektyvumo, priklausomai nuo akustinio lauko garso slėgio ir dažnio, tyrimai. Aprašytas tyrimams atlikti naudotas eksperimentinis stendas ir eksperimentų atlikimo metodika. Akustiniam laukui žadinti naudoti du garso generatoriai: pjezoelektrinis ir aeroakustinis. Atlikus tyrimus nustatyta, kad, didėjant akustinio poveikio dažniui, dalelių koaguliacijos greitis didėja, kai dalelių skersmuo neviršija 1 μm. Efektyviausiai dalelių iki 1 μm skersmens koaguliacijai reikia ultragarsinių dažnių, didesnio nei 1 μm skersmens dalelėms reikia žemesnio dažnio už ultragarsinį.

scholarly journals Influence of Contextual Factors on Soundscape in Urban Open Spaces

2018 ◽  
Vol 8 (12) ◽  
pp. 2524 ◽  
Author(s):  
Xiaolong Zhao ◽  
Shilun Zhang ◽  
Qi Meng ◽  
Jian Kang
Keyword(s):  
Sound Pressure ◽  
Contextual Factors ◽  
Open Spaces ◽  
Acoustic Environment ◽  
Crowd Density ◽  
Significant Difference ◽  
Parabolic Shape ◽  
Acoustic Comfort ◽  
Level Of Sound Pressure ◽  
Central Avenue

The acoustic environment in urban open spaces has played a key role for users. This study analyzed the different effects of contextual factors, including shop openness, season, and commercial function, on the soundscape in two typical commercial pedestrian streets. The following observations were based on a series of measurements, including crowd measurements, acoustic environment measurements, and a questionnaire survey. First, the number of talkers in Central Avenue was greater than the number of talkers in Kuan Alley in cases with the same crowd density, while there was no significant difference in the sound pressure level. When the crowd density increased, acoustic comfort trended downward in Kuan Alley, while the value of acoustic comfort in Central Avenue took a parabolic shape. Second, there was no significant difference between the number of talkers in summer and the number of talkers in winter; however, when crowd density increased by 0.1 persons/m2, the level of sound pressure increased by 1.3 dBA in winter and 2.2 dBA in summer. Acoustic comfort took a parabolic shape that first increased and then decreased in both winter and summer. Regarding commercial function, as the crowd density increased, the number of talkers and the level of sound pressure both increased, while acoustic comfort decreased in three zones with different commercial functions. In addition, a cross-tab analysis was used to discuss the relationship between the number of talkers and the level of sound pressure, and it was found to be positive.

Experimental Investigation of Vortex-Induced Vibration Responses of Tension Riser Transporting Fluid

2009 ◽  
Author(s):  
Yongbo Zhang ◽  
Fanshun Meng ◽  
Haiyan Guo
Keyword(s):  
Experimental Investigation ◽  
Frequency Spectrum ◽  
Cross Flow ◽  
Internal Flow ◽  
Strain Gauges ◽  
Test Results ◽  
Amplitude Response ◽  
Flowing Fluid ◽  
Vortex Induced Vibrations ◽  
Vibration Responses

This paper presents the test results of a vertically tensioned riser model under vortex-induced vibrations. The influence of internal flowing fluid and top tensions on the riser behavior is investigated. Twelve strain gauges were mounted on the riser and both the in-line and cross-flow responses at locations were measured. The frequency spectrum and amplitude response were derived from the strain date. The influences of internal flow and top tensions on two kinds of model risers are analyzed and some conclusions are drawn.

Experimental Investigation of Rotor Rubbing Faults

2012 ◽  
Vol 490-495 ◽  
pp. 1048-1052 ◽  
Author(s):  
Gui Zhen Liu ◽  
Ya Zhe Chen ◽  
Yang Liu ◽  
Bang Chun Wen
Keyword(s):  
Experimental Investigation ◽  
Detailed Analysis ◽  
Frequency Spectrum ◽  
High Frequency ◽  
Nonlinear Response ◽  
Test Bench ◽  
Single Point ◽  
Rotor System ◽  
Rotor Vibration ◽  
Before And After

Established a single-disc rubbing rotor system test-bench ,and can simulate the design of a single point of rubbing and rubbing of the rotor part. In the case of constant speed to ensure that observed in the rubbing rotor vibration under different conditions, the use of waveform, frequency spectrum, Orbit and other detailed analysis of the system before and after rubbing and chaotic properties of nonlinear response the experimental. results show that the occurrence rub rotor system, the system will stimulate a high frequency and fractional-octave, when there will be a serious rub chaos.

Inverse Aeroacoustic Design of Axial Fans Using Genetic Optimization and the Lattice-Boltzmann Method

2013 ◽  
Vol 136 (4) ◽  
Author(s):  
Michael Stadler ◽  
Michael B. Schmitz ◽  
Wolfgang Laufer ◽  
Peter Ragg
Keyword(s):  
Frequency Spectrum ◽  
Lattice Boltzmann ◽  
Design Theory ◽  
Sound Pressure ◽  
Inverse Design ◽  
Free Form ◽  
Geometrical Parameters ◽  
Axial Fan ◽  
Axial Fans ◽  
Free Form Surfaces

The noise emitted by axial fans plays an integral role in product design. When conventional design procedures are applied, the aeroacoustic properties are controlled via an extensive trial-and-error process. This involves building physical prototypes and performing acoustic measurements. In general, this procedure makes it difficult for a designer to gain an understanding of the functional relationship between the noise and geometrical parameters of the fan. Hence, it is difficult for a human designer to control the aeroacoustic properties of the fan. To reduce the complexity of this process, we propose an inverse design methodology driven by a genetic algorithm. It aims to find the fan geometry for a set of given objectives. These include, most notably, the sound pressure frequency spectrum, aerodynamic efficiency, and pressure head. Individual bands of the sound pressure frequency spectrum may be controlled implicitly as a function of certain geometric parameters of the fan. In keeping with inverse design theory, we represent the design of axial fans as a multi-objective multiparameter optimization problem. The individual geometric components of the fan (e.g., rotor blades, winglets, guide vanes, shroud, and diffusor) are represented by free-form surfaces. In particular, each blade of the fan is individually parameterized. Hence, the resulting fan is composed of geometrically different blades. This approach is useful when studying noise reduction. For the analysis of the flow field and associated objectives, we utilize a standard Reynolds averaged Navier–Stokes (RANS) solver. However, for the evaluation of the generated noise, a meshless lattice-Boltzmann solver is employed. The method is demonstrated for a small axial fan, for which tonal noise is reduced.

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