摘要:

A class of hydrodynamic oscillators is being developed which shows considerable promise for sonic and ultrasonic applications involving large acoustic power requirements. These devices convert liquid flow energy into acoustic energy with conversion efficiencies that can exceed 50% in favorable circumstances. The performance characteristics of a low‐frequency (1000 cps) and a high‐frequency (20 kcps) oscillator will be described. Problems associated with the delivery of the generated acoustic energy to the site of its application will be discussed. [This work was supported by the Office of Naval Research.]

ISSN:0001-4966    

DOI:10.1121/1.1918394

出版商:Acoustical Society of America    

年代:1956

数据来源: AIP

摘要:

New technical possibilities continually arise from theoretical studies. However, transposing promising laboratory experiences into industrial applications is only possible with powerful, simple, and good efficiency transmitters. Research is being pursued and has already given interesting results. Among other aims, they specially concern: 1. A friction loudspeaker of long service high acoustical power with high efficiency. 2. A spark generator producing very high peak power pulses for a few microseconds. This device would have to be used for dislocation.

ISSN:0001-4966    

DOI:10.1121/1.1918399

出版商:Acoustical Society of America    

年代:1956

数据来源: AIP

摘要:

Information on the basic characteristics of aircraft noise sources during flight requires that a methodology be established which can adequately determine total acoustic power, directivity, and frequency characteristics from sound pressure measurements. A procedure is presented for transposing from sound‐pressure‐time information received at a stationary ground point to information on the radiation characteristics of the moving source. Included are such physical mechanisms as propagation time lags, energy losses through a diverging sound field, atmospheric absorption losses, and Doppler shifts in frequency. A graphical approach is utilized wherever feasible to facilitate calculation. The method is equally applicable to cases where the microphone is in motion parallel to the axis of an axially symmetrical sound source at rest.

ISSN:0001-4966    

DOI:10.1121/1.1918401

出版商:Acoustical Society of America    

年代:1956

数据来源: AIP