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Licentiate seminar

Experimental study of rotating pipe and jet flows


Defendant Main Advisor Extra Advisor Date
Luca Facciolo Henrik Alfredsson 2003-11-20

Opponent
Mats Sandberg, Högskolan i Gävle

Evaluation committee

Abstract

The present study is an experimental investigation on rotating flows. A special facility has been built in order to produce a turbulent swirling jet generated by a fully developed rotating pipe flow. The work is so naturally divided into two main parts: the turbulent rotating pipe flow and the swirling jet. The turbulent pipe flow has been investigated at the outlet of the pipe both by hot-wire anemometry and LDV. The LDV has been also used to measure the axial velocity component inside the pipe. The research presents the e ects of the rotation and Reynolds number (12000< Re <33500) on a turbulent flow providing a theoretical curve for the azimuthal-radial Reynolds stress and comparing the experimental results with theory and simulations. Especially a comparison with the recent theoretical results by Oberlack (1999) is made. The rotating pipe flow also represents the initial condition of the jet. The rotation applied to the jet drastically changes the characteristics of the flow field. The present experiment has been performed mainly for weak swirl numbers (0< S <0.5). All the velocity components and their moments are presented together with spectra along the centreline as well as entrainment data. The data from the two di erent techniques used have been compared to prove the accuracy of the results since hot-wire and LDV measurements are a ected by di erent kind of problems. In the specific case a X-hot wire that su er a velocity gradient has been used and its data have been treated with an a posteriori correction and then validated using the LDV measurements. Descriptors: Fluid mechanics, rotating pipe flow, swirling jet, turbulence, hot-wire anemometry, LDV.
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