Accession Number:

AD0608808

Title:

EXPERIMENTS CONCERNING THE HARTMANN WHISTLE

Descriptive Note:

Corporate Author:

CALIFORNIA UNIV LOS ANGELES

Personal Author(s):

Report Date:

1964-09-01

Pagination or Media Count:

82.0

Abstract:

The Hartmann whistle, in its most basic configuration, consists of a flat-bottomed, cylindrical cavity which is axially aligned with a supersonic air jet of the same diameter. Discrete-frequency oscillations of the enclosed air column are driven at large amplitudes when the cavity is located within certain regions of the cellular structure of the jet. An optical and acoustical study of the phenomenon is described, together with that of the Hartmann pulsator. In the latter form the whistle has the small cavity replaced by a large Helmholtz-type resonator with the same orifice diameter, resulting in a large- amplitude aeroacoustic oscillator with a periodic time of several orders of magnitude greater than for the regular whistle. The underlying cause of the newly discovered bistable condition of the normal shock-disc located in the air stream between the nozzle and the cavity orifice is an important aspect which makes possible a presently qualitative theory of operation which accounts for the principal features of the Hartmann whistle and its direct derivatives. Some other aspects still requiring further elucidation and which are the subject of continuing effort are mentioned. The Report includes a brief review of the currently available literature pertaining to the phenomenon. Author

Subject Categories:

  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE