Experimental characterization of the sound power radiated by impinging supersonic jets

In recent years, the aerodynamic noise generated by centrifugal fans is receiving increasing attention because of strict environmental noise level restrictions and customer demands. The noise generated by fans is due to aerodynamic sources and to other several sources, such as, for instance, by the fan drive, by bearings and gearing, and, when present, by the inverter. Additional noise sources can be also due to structural resonance effects induced by periodic forces associated with the blade passing frequency or vortex shedding. Usually, these additional noise sources are dominated by aerodynamic noise generated by the fan, in particular when the intake and outlet of the fan are free. On the other side, if fan intake and outlet are ducted, the additional sources can relevantly contribute to overall sound generation. In this paper, an experimental characterization of the noise generated by industrial centrifugal fans when both inlet and outlet are ducted is presented. To do this, an experimental facility has been design and set up, and the sound power measured by means of the procedures outlined in the ISO 3746 international standard. A number of different type of centrifugal fan (straight-, forward- and backward blade) in different working conditions were tested, resulting in 133 different runs. These amount of data were then processed and a general formula for fan noise estimation obtained as a function of the geometrical and fluid dynamic parameters is derived. Moreover, specific coefficients with respect to blade geometry for the determination of the A-weighted frequency spectrum are presented. Finally, auxiliary devices or other features, such as inverter, thickness of the casing, acoustic insulation, electric motor shaft, are analyzed and some general rules to estimate their influence on sound power level quantified.

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Experimental Characterization and Evaluation of the Vibroacoustic Field of Hydraulic Pumps: The Case of an External Gear Pump

Energies ◽

10.3390/en13246639 ◽

2020 ◽

Vol 13 (24) ◽

pp. 6639

Author(s):

Sangbeom Woo ◽

Andrea Vacca

Keyword(s):

Operating Conditions ◽

Plate Motion ◽

Sound Power ◽

Gear Pump ◽

Experimental Characterization ◽

Noise Performance ◽

Noise Sources ◽

Iso Standards ◽

Minimum Number

This paper presents the experimental characterization of the vibroacoustic fields and the evaluation of noise performances of hydraulic pumps. Research on hydraulic pump noise has traditionally focused on the fluid-borne noise sources, and very often the analyses of vibration and noise have been performed focusing on a few local points. This trend results in the lack of investigation on the overall behaviors of vibroacoustic fields of hydraulic pumps, and it has been one of the obstacles to understand the complete mechanisms of noise generation. Moreover, despite the existence of the ISO standards for the determination of noise levels, diverse metrics have been used for the evaluation of noise performances of the pumps, but the adequacy of these metrics has not been carefully examined. In this respect, this paper aims at introducing a way to characterize and interpret the measured vibroacoustic field and providing proper methods which are also capable of applying the ISO standards for the fair assessment of pump noise performances. For the characterization of the vibroacoustic field, operational deflection shapes (ODS) and corresponding radiated sound fields are visualized at harmonics of the pumping frequency by using a spectral analysis. Observations are made regarding the motions of the pump and its mounting plate and the resultant radiated noise, depending on the frequency, as well as their correlation. A numerical analysis using the Rayleigh integral equation is also performed to further investigate the contribution of the mounting plate motion on the noise radiation. For the evaluation of noise performance, two different units are tested at multiple operating conditions, and comparisons are made based on their measured sound power levels (SWLs) and sound pressure levels (SPLs). The results emphasize the importance of SWL measurement for the fair noise performance evaluation, and the two methods are proposed as practices to determine the minimum number of measurement points for practicability and to have reliable sound power determination for hydraulic pumps.

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Experimental characterization of the solid phase chaotic dynamics in three-phase fluidization

International Journal of Multiphase Flow ◽

10.1016/s0301-9322(97)88294-8 ◽

1996 ◽

Vol 22 ◽

pp. 113

Author(s):

M Cassanello

Keyword(s):

Chaotic Dynamics ◽

Solid Phase ◽

Experimental Characterization ◽

Three Phase

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Experimental characterization of a laminar diffusion flame in micro-gravity

Journal de Chimie Physique ◽

10.1051/jcp:1999190 ◽

1999 ◽

Vol 96 (6) ◽

pp. 1022-1030 ◽

Cited By ~ 3

Author(s):

T. Vietoris ◽

P. Joulain ◽

J. L. Torero

Keyword(s):

Diffusion Flame ◽

Experimental Characterization ◽

Laminar Diffusion Flame ◽

Laminar Diffusion ◽

Micro Gravity

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Experimental Characterization of the Reliability of 3-Terminal Dual-Damascene Copper Interconnect Trees

MRS Proceedings ◽

10.1557/proc-716-b8.13 ◽

2002 ◽

Vol 716 ◽

Cited By ~ 4

Author(s):

C. L. Gan ◽

C. V. Thompson ◽

K. L. Pey ◽

W. K. Choi ◽

F. Wei ◽

...

Keyword(s):

Stress Conditions ◽

Experimental Characterization ◽

Contact Lines ◽

Tree Structures ◽

Similar Test ◽

Dual Damascene ◽

Copper Interconnect ◽

Test Conditions

AbstractElectromigration experiments have been carried out on simple Cu dual-damascene interconnect tree structures consisting of straight via-to-via (or contact-to-contact) lines with an extra via in the middle of the line. As with Al-based interconnects, the reliability of a segment in this tree strongly depends on the stress conditions of the connected segment. Beyond this, there are important differences in the results obtained under similar test conditions for Al-based and Cu-based interconnect trees. These differences are thought to be associated with variations in the architectural schemes of the two metallizations. The absence of a conducting electromigrationresistant overlayer in Cu technology, and the possibility of liner rupture at stressed vias lead to significant differences in tree reliabilities in Cu compared to Al.

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EXPERIMENTAL CHARACTERIZATION OF VVER-440 REACTOR CONTAINMENT TYPE SPRAY NOZZLE

Atomization and Sprays ◽

10.1615/atomizspr.2015011801 ◽

2016 ◽

Vol 26 (3) ◽

pp. 235-255 ◽

Cited By ~ 1

Author(s):

Jeanne Malet ◽

Z. Parduba

Keyword(s):

Spray Nozzle ◽

Experimental Characterization

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Experimental Characterization of Mechanical Behavior of Cord-Rubber Composites

Tire Science and Technology ◽

10.2346/1.2150974 ◽

1982 ◽

Vol 10 (1) ◽

pp. 37-54 ◽

Cited By ~ 11

Author(s):

M. Kumar ◽

C. W. Bert

Keyword(s):

Response Characteristic ◽

Cord Compression ◽

Complete Characterization ◽

Strain Response ◽

Strain Gages ◽

Experimental Characterization ◽

Rubber Composites ◽

Stress Strain ◽

Strain Data

Abstract Unidirectional cord-rubber specimens in the form of tensile coupons and sandwich beams were used. Using specimens with the cords oriented at 0°, 45°, and 90° to the loading direction and appropriate data reduction, we were able to obtain complete characterization for the in-plane stress-strain response of single-ply, unidirectional cord-rubber composites. All strains were measured by means of liquid mercury strain gages, for which the nonlinear strain response characteristic was obtained by calibration. Stress-strain data were obtained for the cases of both cord tension and cord compression. Materials investigated were aramid-rubber, polyester-rubber, and steel-rubber.

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