whistle

(redirected from whistles)
Also found in: Dictionary, Thesaurus, Medical, Idioms.

whistle

1. a device for making a shrill high-pitched sound by means of air or steam under pressure
2. Music any pipe that is blown down its end and produces sounds on the principle of a flue pipe, usually having as a mouthpiece a fipple cut in the side

Whistle

 

a generator that converts the energy of a fluid stream into the energy of acoustic vibrations. Unlike a siren, a whistle has no moving parts and is therefore simpler to manufacture and use. Depending on the working fluid for which they are designed, whistles are classified as gas-jet or jet liquid. Gas-jet whistles in turn are subdivided into low- and high-pressure types. As a rule, low-pressure whistles have a relatively high efficiency but generate little power, and until recently they were used only for signaling. However, with methods for increasing power output, uses have now been found for whistles in industry, for example, in the coagulation of aerosols and in the acceleration of processes of heat and mass transfer.

The simplest low-pressure whistle is the familiar lip whistle, which consists of a slotted inlet and a resonance chamber, usually cylindrical in shape. Air fed into the inlet is split into two streams by the sharp edge of the resonator. One stream exits into the surrounding medium, while the other enters the resonance chamber, thereby increasing the pressure. After a period of time that depends on the size of the chamber, the second stream interrupts the main flow, as a result of which there is a periodic compression and rarefaction of the air that is propagated as acoustic waves. Lip whistles ordinarily operate at air pressures not exceeding 1.4 atmospheres and generate acoustic power of the order of 1 watt. Some designs enable several kilowatts of power to be generated.

The ultrasonic Galton whistle and vortex whistles are further examples of low-pressure devices. Vortex whistles have a cylindrical chamber into which a gas or liquid is introduced tangentially. A narrow tube extends along the axis of the chamber, and it is through this tube that the gas exits, radiating sound energy. Elastic vibrations are induced by a combination of the pressure decrease along the whistle axis that results from vortex motion and the periodic pressure equalization that results from the rush of gas from the atmosphere into the tube’s outlet. At frequencies up to 30 kilohertz, the power output of a vortex whistle is usually of the order of several watts. A representative high-pressure whistle is the Hartmann generator, which has a maximum power output of 0.5 kilowatt.

The design and operating principles of jet liquid whistles are analogous to those of the gas-jet type. The most common are lamellar jet liquid whistles, which function by using a liquid stream under high pressure to excite resonant vibrations of the vibrator—a blade or rod.

REFERENCES

Shkol’nikova, P. Sh. “Vozdukhostruinye generatory akusticheskikh kolebanii dlia koaguliatsii aerozolei.” Akusticheskii zhurnal, 1963, vol. 9, no. 3, pp. 368–75.
Bergmann, L. Ul’trazvuk i ego primenenie v nauke i tekhnike, 2nd ed. Moscow, 1957. (Translated from German.)

IU. IA. BORISOV

References in classic literature ?
He wondered if ever he could get used to working in a place like this, where the air shook with deafening thunder, and whistles shrieked warnings on all sides of him at once; where miniature steam engines came rushing upon him, and sizzling, quivering, white-hot masses of metal sped past him, and explosions of fire and flaming sparks dazzled him and scorched his face.
When you combine the ideas of whistles at night, the presence of a band of gipsies who are on intimate terms with this old doctor, the fact that we have every reason to believe that the doctor has an interest in preventing his stepdaughter's marriage, the dying allusion to a band, and, finally, the fact that Miss Helen Stoner heard a metallic clang, which might have been caused by one of those metal bars that secured the shutters falling back into its place, I think that there is good ground to think that the mystery may be cleared along those lines.
That ain't a police whistle: that's a sporting whistle.
A sound of carts and 'orses there was, and a sound of cabs and omnibuses, and then a lot of whistling, shrill whistles, whistles that froze 'is marrer.
It is frightful--this taking to buying whistles and blowing them in everybody's hearing.
Next comes Nibs, the gay and debonair, followed by Slightly, who cuts whistles out of the trees and dances ecstatically to his own tunes.
As a stepping-stone I obtained an appointment in the American ambulance service and was on my way to France when three shrill whistles altered, in as many seconds, my entire scheme of life.
fashion on straight moose meat, now heard the hoarse whistles calling his hundreds of laborers to work, and watched them toil under the white glare of the arc-lamps.
No wind whistles outside the lonely dwelling--no cry of bird or beast is heard.
He drops his bridle on the pommel of his saddle, whistles to his pony, and disappears in the mist; riding with his hands in his pockets, and his pipe in his mouth, as composedly as if he were sitting by his own fireside at home.
He bounced out at her from behind doors, booed at her in dark entries, clutched her feet as she went up stairs, startled her by shrill whistles right in her ear, or sudden tweaks of the hair as he passed her in the street; and as sure as there was company to dinner, he fixed his round eyes on her, and never took them off till she was reduced to a piteous state of confusion and distress.
If the engine whistles, let it whistle till it is hoarse for its pains.