Croatian Union of Mechanical Engineers and Naval Architects
Abstract
The utilization of constant temperature anemometry (CTA) system for the
measurement of mean oscillating velocity of air at negligible compressibility
is discussed in this paper. The measurements were conducted at a station of
self-excited oscillations in a circular cross sectional pipe following the collapse
of the elastic test tube of a Starling resistor in a flow Reynolds number range
of 7,000 ≤ Re ≤ 94,000. The cross-sectional traverse of the hot-wire probe at
the measurement station in a frequency (f) range of 13Hz ≤ f ≤ 107Hz were
conducted. The cross sectional oscillating velocity profile was determined
by using the ensembled averages of oscillating velocity data. The position of
the hot-wire probe corresponding to the mean axial oscillating velocity was
determined to be approximately 0.755 of pipe radius from the centreline in the
covered ranges of Re and f.U ovom radu je prikazana upotreba anemometra u načinu rada s konstantnom temperaturom za mjerenje srednjih oscilirajućih brzina zraka pri zanemarivoj stlačivosti. Mjerenja su vršena pri samopobudnim oscilacijama u cijevi kružnog poprečnog presjeka postavljene nakon prigušne Starling-ove cijevi, u rasponu Reynoldsove značajke 7 000 ? Re ? 94,000. Raspon frekvencija mjerne sonde je u rasponu 13Hz ? f ? 107Hz.
Profil oscilirajućih brzina toka zraka u poprečnom presjeku cijevi je određen skupom uprosječenih podataka dobivenih mjerenjem. Pozicija mjerne sonde anemometra s toplom niti u odnosu na srednju
aksijalnu brzinu toka zraka je određena da iznosi 0.755 radijusa cijevi od simetrale cijevi za navedene raspone Re značajke i frekvencije