The Eckert number phenomenon: experimental investigations on the heat transfer from a moving wall in the case of a rotating cylinder

Date
2004
Authors
Gschwendtner, MA
Supervisor
Item type
Journal Article
Degree name
Journal Title
Journal ISSN
Volume Title
Publisher
Springer-Verlag
Abstract

The Eckert number phenomenon was investigated theoretically by Geropp in 1969 and describes a reversal in heat transfer from a moving wall at an Eckert number Ec ≈ 1. In this report the Eckert number phenomenon is confirmed experimentally for the first time. For that purpose the heat transfer from a heated, vertically rotating cylinder in a crossflow was investigated. In order to perform the experiments in a range where the predicted phenomenon occurs, extreme rotational speeds were necessary. A heating concept had to be developed which allowed an input of heating power independent of the speed and which therefore had to be contact-free. The results show, among other things, that the temperature difference between the wall and the surrounding fluid has a significant effect on the predicted reversal of heat transfer at the wall. Moreover, maximum heat transfer occurs at an Eckert number Ec ≈ 0.3, which is of great importance for the cooling of hot surfaces in a gas-flow.

Description
Keywords
Eckert number , Nusselt number , Heat transfer , Rotating cylinder , Adiabatic wall temperature , Boundary layer , Dissipation , Frictional heat
Source
Heat and Mass Transfer/Waerme- und Stoffuebertragung, vol.40(6-7), pp.551 - 559
Publisher's version
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