Acoustic Tests of Industrial Vehicles International (IVI) Marine Vibrators
Abstract
The acoustic performance of a commercially available marine vibrator was measured under a variety of conditions at the NUSC Lake Seneca Test Facility. One setup used calibrated hydrophones in the horizontal and vertical planes of vibrator's acoustic center to measure the free-field performance of the single vibrator. Another similar setup was used to measure the performance of two vibrators spaced a quarter-wavelength apart at 100 Hz. Interaction between the two vibrators was assessed with the latter setup and azimuthal pattern for various phase differences between the vibrators were also measured. Definitive free-field source level results under controlled conditions show that the vibrator is omnidirectional at least up to 100 Hz. The maximum value of source level is 213 dB re 1 Pa at 1 m at 165 Hz. Parametric results of source depth, hydraulic supply pressure and drive signal level are presented. For example, for a given hydraulic flow rate, the source level varies approximately as the ratio of the hydraulic supply pressures. Interaction between two vibrators spaced 12 ft. apart is minimal at least down to 25 Hz. Measured directivity patterns of the two vibrators agreed well with simple theory. Keywords: Underwater sound generators; Projectors (Sound Generators).
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 24, 1989
- Accession Number
- ADA206982
Entities
People
- Roy C. Johnson
Organizations
- United States Naval Research Laboratory