Accession Number:

ADA167693

Title:

Sound Enhancement and Modulation of Self-Resonating Cavitating Jets for Underwater Noise Generation.

Descriptive Note:

Technical rept.,

Corporate Author:

TRACOR HYDRONAUTICS INC LAUREL MD

Report Date:

1985-07-01

Pagination or Media Count:

85.0

Abstract:

The natural tendency of an axisymmetric submerged jet to form large scale structures in its shear layer is enhanced using acoustic oscillators and hydroacoustic oscillations. Organ pipe tube lengths are tuned to the jet natural oscillation frequency to form very effective noise generators. The principle of operation of this generator, STRATOJET TM, is described in this report, and the influence of the various parameters tube length, nozzle diameter, pressure drop across the nozzle, and ambient pressure are investigated. Scaling effects, cavitation influence on the oscillations, and characteristics of noise decay with distance are presented. The capability of modulation of the generated noise is investigated and its feasibility is demonstrated. Further improvement of the STRATOJET noise generation capabilities are studied. Several schemes aiming at manipulation of the ring vortex circulation are described. Opposing jets and solid enhancers configurations were found to be very effective, and amplification factors as high as 6 were measured without use of any additional energy. Even without enhancers, the efficiency of a STRATOJET is seen to be more than two orders of magnitude higher than that of conventional cavitating jets. This strongly suggests that a system based on a STRATOJET, possibly with an enhancement scheme, would be very effective noise generation.

Subject Categories:

  • Acoustics
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE