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Development of a two-wire thermal flow sensor for industrial applications (2003)

Al-Salaymeh, A. ; Alhusein, M. ; Durst, F.

Bingley : Emerald

Journal of quality in maintenance engineering 9 (2003), S. 113-131

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ISSN: 1355-2511

Source: Emerald Fulltext Archive Database 1994-2005

Topics: Technology , Economics

Notes: Thermal flow sensors with a wide dynamic range are at present not available in spite of the large demand which exists for such sensors in practical fluid flow measurements. In this paper, it is shown that the velocity range of a "time-of-flight" thermal flowmeter for slowly changing flows can be increased by using wires (or other heating/sensing elements) with large thermal inertia (time constant) and heating the sending wire with a continuous sinusoidal current, instead of discrete, very short, square-wave pulses as in the usual pulsed-wire anemometer. The device described here uses two parallel wires of 12.5µm diameter and its usable speed range is 0.05 to 25m/s. Although the present thermal flowmeter can be applied as a point measurement device, the main applications are in pipe flow, especially at very low flow rates. The high sensitivity at low flow rates makes the device especially suitable for this purpose.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1108/13552510310482370

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Experimental investigation of contraction in single- and two-phase flow through sharp-edged short orifice (1999)

Shannak, B. ; Friedel, L. ; Alhusein, M. ; [et al.]

Springer

Forschung im Ingenieurwesen 64 (1999), S. 291-295

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ISSN: 1434-0860

Source: Springer Online Journal Archives 1860-2000

Topics: Technology

Description / Table of Contents: Zusammenfassung Der eingeschnürte bzw. engste Strömungsquerschnitt (Vena Contracta) bei der Strömung von Wasser, Luft und von Luft/Wassergemischen durch scharfkantige, kurze Blenden in Rohren wurde gemessen. Bei unterkritischer Einphasenströmung liegt die Kontraktionszahl zwischen 0,62 und eins. Bei Zweiphasenströmung stellt sich eine Kontraktion nur bei Blasen- und bei Sprühströmung ein.

Notes: Abstract The flow contraction through sharp-edged short orifices respectively the narrowest flow cross-section or the vena contracta has been measured for water, air and air/water mixture. The results demonstrate that the contraction in the case of subcritical single-phase flow is restricted to values between 0.62 and one, while in the two-phase flow it is limited to very narrow ranges of air mass flow qualities where the flow regime is specified as bubbly or spray.