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The rotary subwoofer: A controllable infrasound source
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10.1121/1.3082115
/content/asa/journal/jasa/125/4/10.1121/1.3082115
http://aip.metastore.ingenta.com/content/asa/journal/jasa/125/4/10.1121/1.3082115

Figures

Image of FIG. 1.
FIG. 1.

The rotary subwoofer consists of a hub of radius rotating at a fixed rate of with blades of length and width modulated in pitch by signal with frequency .

Image of FIG. 2.
FIG. 2.

Photograph of the installed source. (a) view inside the building showing the function generator, amplifier, motor controller, and motor and (b) view from the exterior showing the main rotor hub and blades.

Image of FIG. 3.
FIG. 3.

Acoustic power spectra measured at range of with fan rotation frequency of . (a) shows signal frequencies of and and (b) and .

Image of FIG. 4.
FIG. 4.

SPL from measurements at with versus signal frequency . rms voltage amplitude of the drive signal is denoted next to each measurement.

Image of FIG. 5.
FIG. 5.

SPL from measurements at 1 and with versus signal frequency . Solid symbols were recorded at a range of ; open symbols were recorded at a range of and corrected to . rms voltage amplitude of the drive signal is denoted next to each measurement.

Image of FIG. 6.
FIG. 6.

Composite signal transfer function with values of coherence .

Image of FIG. 7.
FIG. 7.

Angular response measured at a range of for the drive frequencies , 8, . Data are SPL in units of . The axis of the fan is aligned at 0°.

Image of FIG. 8.
FIG. 8.

Blade velocity distributions from the blade pitch modulation frequency and the fan rotation .

Image of FIG. 9.
FIG. 9.

Effective particle velocity normal to the blade is modeled as the sum of the normal component of fan rotational velocity with the effective velocity from the blade pitch modulation .

Tables

Generic image for table
TABLE I.

Blade pitch angles in degrees as a function of rms input signal voltage

Generic image for table
TABLE II.

Model results for a fan speed of compared to measured values (SPL shown in Fig. 5) at a range of . Data and model SPL are decibels re .

Generic image for table
TABLE III.

Model results for a fan speed of compared to measured values (SPL shown in Fig. 4) at a range of . Data and model SPL are decibels re .

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/content/asa/journal/jasa/125/4/10.1121/1.3082115
2009-04-01
2014-04-19
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: The rotary subwoofer: A controllable infrasound source
http://aip.metastore.ingenta.com/content/asa/journal/jasa/125/4/10.1121/1.3082115
10.1121/1.3082115
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