VELOCITY OF SOUND | ScienceGate

A galvanic current passes from the batteries at the Royal Observatory, Cape Town, at 1 o’clock, and discharges a gun at the Castle, and through relays drops a time-ball at Port Elizabeth. It appeared to the author that a valuable determination of the velocity of sound might be obtained by measuring upon the chronograph of the Observatory the interval between the time of the sound reaching some point near the gun and that of its arrival at the Observatory. As there is only a single wire between the Observatory and Cape Town, some little difficulty was experienced in making the necessary arrangements, without any interference with the 1 o’clock current to Port Elizabeth; but this difficulty was overcome by a plan which the author describes, and which was brought into successful operation on Feb. 27, 1871. The experiments could not have been carried out, on account of the encroachment they would have made on the time of the Observatory staff, had it not been for the assistance of J. Den, Esq., the acting manager of the Cape Telegraph Company, to whom the author is indebted for the preparation of a good earth-connexion near the gun, for permission to Mr. Kirby, a gentleman attached to the telegraph office, to assist in the experiments, and for a general superintendence of the arrangements at Cape Town. The observed times of hearing the sound were recorded on the chronograph by two observers, situated one (Mr. Kirby) at a distance of 641 feet from the gun, the other (Mr. Mann) at the Observatory, at a distance of 15,449 feet from the gun. The former distance was sufficient to allow the connexion of the main wire to be broken at the telegraph office after the gun had been fired, but before the sound reached the first observer.

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Detailed Analysis of the Acoustic Mode Shapes of an Annular Combustion Chamber

Volume 2: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations ◽

10.1115/99-gt-113 ◽

1999 ◽

Cited By ~ 4

Author(s):

Günther Walz ◽

Werner Krebs ◽

Stefan Hoffmann ◽

Hans Judith

Keyword(s):

Boundary Conditions ◽

Acoustic Mode ◽

Mode Shapes ◽

Maximum Deviation ◽

Minor Importance ◽

Velocity Of Sound ◽

Fe Method ◽

Shift Frequency ◽

Space Dependence ◽

Eigenfrequency Spectrum

To get a better understanding of the formation of thermoacoustic oscillations in an annular gasturbine combustor, an analysis of the acoustic eigenmodes has been conducted using the Finite Element (FE) method. The influence of different boundary conditions and a space dependent velocity of sound has been investigated. The boundary conditions actually define the eigenfrequency spectrum. Hence, it is crucial to know e.g. the burner impedance. In case of the combustion system without significant mixing air addition considered in this paper, the space dependence of the velocity of sound is of minor importance for the eigenfrequency spectrum leading to a maximum deviation of only 5% in the eigenvalues. It is demonstrated that the efficiency of the numerical eigenvalue analysis can be improved by making use of symmetry, by splitting the problem into several steps with alternate boundaries conditions, and by choosing the shift frequency ωs in the range of frequencies one is interested in.

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Magnetic field dependence of the velocity of sound in ultrapure Cd and Cu (Experimental determination using a continuous-wave resonance technique)

Ultrasonics ◽

10.1016/0041-624x(69)90957-3 ◽

1969 ◽

Vol 7 (3) ◽

pp. 212

Keyword(s):

Magnetic Field ◽

Experimental Determination ◽

Field Dependence ◽

Magnetic Field Dependence ◽

Continuous Wave ◽

Velocity Of Sound ◽

Resonance Technique ◽

Wave Resonance

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