anemometer

anemometer
—anemometric /an'euh moh me"trik/, anemometrical, adj. —anemometrically, adv.
/an'euh mom"i teuhr/, n. Meteorol.
any instrument for measuring the speed of wind.
[1720-30; ANEMO- + -METER]

* * *

Instrument for measuring the speed of airflow.

The most familiar instruments for measuring wind speeds are the revolving cups that drive an electric generator (useful range approximately 5–100 knots). For very low airspeeds, a unit in which revolving vanes operate a counter measures the airspeed. For strong, steady wind speeds (in wind tunnels and aboard aircraft in flight), a pitot-tube anemometer is often used; the pressure difference between the interior of the tube and the surrounding air can be measured and converted to airspeed.

* * *

 device for measuring the speed of airflow in the atmosphere, in wind tunnels, and in other gas-flow applications. Most widely used for wind-speed measurements is the revolving-cup electric anemometer, in which the revolving cups drive an electric generator. The output of the generator operates an electric meter that is calibrated in wind speed. The useful range of this device is approximately from 5 to 100 knots. A propeller may also be used to drive the electric generator, as in the propeller anemometer. In another type of wind-driven unit, revolving vanes operate a counter, the revolutions being timed by a stopwatch and converted to airspeed. This device is especially suited for the measurement of low airspeeds.

      The fact that a stream of air will cool a heated object (the rate of cooling being determined by the speed of the airflow) is the principle underlying the hot-wire anemometer. An electrically heated fine wire is placed in the airflow. As the airflow increases, the wire cools. In the most common type of hot-wire anemometer, the constant-temperature type, power is increased to maintain a constant wire temperature. The input power to the hot wire is then a measure of airspeed, and a meter in the electrical circuit of the hot wire can be calibrated to indicate airspeed. This device is useful for very low airspeeds, below about 5 miles (8 km) per hour. The kata thermometer is a heated-alcohol thermometer; the time it takes to cool is measured and used to determine air current. It is useful for measuring low speeds in studies of air circulation.

      A stream of air striking the open end of a tube closed at the other end will build up pressure within the tube. The difference in pressure between the interior of this tube (called a pitot tube) and the surrounding air can be measured and converted to airspeed. Pitot tubes are also used to measure the flow of liquids, particularly in the course of flume studies in fluid mechanics. This anemometer is most useful, however, in strong, steady air streams, such as in wind tunnels and aboard aircraft in flight. With modifications, it can be used to measure supersonic air flow. Another type of pressure anemometer is the venturi tube, which is open at both ends and of larger diameter at the ends than at the middle. Airspeed is determined by measuring the pressure at the constriction in the tube. Venturi tubes have some applications in industry.

* * *


Universalium. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • Anemometer [1] — Anemometer (Windmesser), Instrumente zur Bestimmung der Geschwindigkeit bewegter Luft, finden sowohl auf meteorologischen Stationen zur Ermittlung der Windgeschwindigkeit, des Winddrucks und häufig auch der Windrichtung, als auch im Bergbau zur… …   Lexikon der gesamten Technik

  • Anemometer [5] — Anemometer. Die Firma Georg Rosenmüller in Dresden Neustadt baut neuerdings Anemometer zum Einbau und Anschluß an das Ende einer Rohrleitung zur Messung der in Rohrleitungen fließenden Luft oder Gasmengen (Fig. 1 u. 2). Durch schlanke konische… …   Lexikon der gesamten Technik

  • Anemometer [4] — Anemometer. Zur Messung von Gichtgasmengen führt die Firma R. Fueß neuerdings Anemometer nach nebenstehender Fig. 1 aus. Dasselbe besteht aus einem Schutzring von ca. 70 mm Durchmesser, in welchem das Windrad in Steinlagern läuft und den Zeiger… …   Lexikon der gesamten Technik

  • Anemomēter — (griech., »Windmesser«), Instrument zur Bestimmung der Stärke oder Geschwindigkeit des Windes. Fig. 1. Wildsche Windfahne. Bei der Wildschen Windfahne (Fig. 1) dreht sich oberhalb der eigentlichen Windfahne eine senkrecht herabhängende… …   Meyers Großes Konversations-Lexikon

  • Anemometer [2] — Anemometer, in der Meteorologie Instrumente zur Messung der Windgeschwindigkeit. Sie zerfallen in Druck , Sang und Rotationsanemometer; die beiden ersteren liefern Einzelwerte: die Windgeschwindigkeit zur Zeit der Beobachtung; letztere liefern… …   Lexikon der gesamten Technik

  • Anemometer [3] — Anemometer sind in den letzten Jahren infolge der Wichtigkeit der Windmessungen für die Aeronautik und wegen ihrer Bedeutung für technische Zwecke vielfach ausgestaltet worden. [14] Die Sang und Druckanemometer eignen sich ihrer kleinen, dem Wind …   Lexikon der gesamten Technik

  • Anemometer — An e*mom e*ter, n. [Gr. ? wind + meter.] An instrument for measuring the force or velocity of the wind; a wind gauge. [1913 Webster] …   The Collaborative International Dictionary of English

  • anemometer — (n.) 1727, from ANEMO (Cf. anemo ) wind + METER (Cf. meter) …   Etymology dictionary

  • anemometer — ► NOUN ▪ an instrument for measuring the speed of the wind or other flowing gas. ORIGIN from Greek anemos wind …   English terms dictionary

  • anemometer — [an΄ə mäm′ət ər] n. a gauge for determining the force or speed of the wind, and sometimes its direction; wind gauge …   English World dictionary

  • Anemometer — A hemispherical cup anemometer of the type invented in 1846 by John Thomas Romney Robinson Cup ty …   Wikipedia

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”