Presentation Title

Controlling the Spatial Orientation of a Resonant Acoustic Mode

Faculty Mentor

Dr. Paul K. Dixon

Start Date

23-11-2019 10:45 AM

End Date

23-11-2019 11:30 AM

Location

242

Session

poster 4

Type of Presentation

Poster

Subject Area

physical_mathematical_sciences

Abstract

Controlling the Spatial Orientation of a Resonant Acoustic Mode

Authors: Alexis Lopez, David Gonzalez Cornejo

Mentor: Paul K. Dixon, Department of Physics, California State University San Bernardino

We have investigated resonant acoustic mode selection in a simple cylindrical system. The overarching long-term objective of the larger project, of which this is an early part, is to induce a nonlinear coupling of slowly rotating high power acoustic modes to the macroscopic flow of gas through a chamber, with the hope of inducing a macroscopic flow of the gas purely acoustically. We designed and built a thin cylindrical resonant cavity with six small speakers arranged uniformly around the outer edge of the cavity. We also designed and built the electronics and software so that we could control the frequency, amplitude, and turn the six speakers on and off automatically. We monitored the signal with small microphones (up to three simultaneously) that could be positioned as desired; this data was collected automatically as well. Our first experiments were frequency sweeps of the system to identify and characterize the various cylindrical acoustical modes of the system. Once we identified the (1,0) mode, we then drove that particular mode using opposing speakers in opposite polarity. By switching from one pair of speakers to the next, it was our hope to rotate the spatial orientation of the resonant mode, cycling through the three pairs of speakers sequentially to rotate the mode. Surprisingly, we found that the system does not freely switch mode orientation to align with the drive speakers as expected.

[Keywords: Acoustic modes, helical mode, resonant frequency]

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Nov 23rd, 10:45 AM Nov 23rd, 11:30 AM

Controlling the Spatial Orientation of a Resonant Acoustic Mode

242

Controlling the Spatial Orientation of a Resonant Acoustic Mode

Authors: Alexis Lopez, David Gonzalez Cornejo

Mentor: Paul K. Dixon, Department of Physics, California State University San Bernardino

We have investigated resonant acoustic mode selection in a simple cylindrical system. The overarching long-term objective of the larger project, of which this is an early part, is to induce a nonlinear coupling of slowly rotating high power acoustic modes to the macroscopic flow of gas through a chamber, with the hope of inducing a macroscopic flow of the gas purely acoustically. We designed and built a thin cylindrical resonant cavity with six small speakers arranged uniformly around the outer edge of the cavity. We also designed and built the electronics and software so that we could control the frequency, amplitude, and turn the six speakers on and off automatically. We monitored the signal with small microphones (up to three simultaneously) that could be positioned as desired; this data was collected automatically as well. Our first experiments were frequency sweeps of the system to identify and characterize the various cylindrical acoustical modes of the system. Once we identified the (1,0) mode, we then drove that particular mode using opposing speakers in opposite polarity. By switching from one pair of speakers to the next, it was our hope to rotate the spatial orientation of the resonant mode, cycling through the three pairs of speakers sequentially to rotate the mode. Surprisingly, we found that the system does not freely switch mode orientation to align with the drive speakers as expected.

[Keywords: Acoustic modes, helical mode, resonant frequency]