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Licentiate seminar

A study of heat transfer from cylinders in turbulent flows by using thermochromic liquid crystals


Defendant Main Advisor Extra Advisor Date
Roland Wiberg Noam Lior Fritz Bark 2004-01-23

Opponent
Dan Loyd, Linköpings universitet

Evaluation committee

Abstract

In gas quenching, metal parts are rapidly cooled from high temperatures, and the convection heat transfer coefficient distributions are of importance for the hardness and the distortion (the shape nonuniformities) of the quenched parts. Thermochromic liquid crystals (TLC) and a thin foil techniques, were investigated and used for studies of a circular cylinder in axial flows, affected and not affected by upstream flow modifying inserts. Quadratic prisms in cross flows were also studied, a single prism, two prisms arranged in-line, and for four prisms arranged in a square pattern. In this study, particle image velocimetry (PIV) was used for visualization of the flow, giving physical insight to the convection heat transfer data. Further, relations of the type Nu=CRe^e were established. The TLC and thin foil techniques were also used to indicate the dimensions of separated flow regions.
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