Aj. Neely et al., EXTENDED SURFACE CONVECTIVE COOLING STUDIES OF ENGINE COMPONENTS USING THE TRANSIENT LIQUID-CRYSTAL TECHNIQUE, Proceedings of the Institution of Mechanical Engineers. Part A, Journal of power and energy, 211(3), 1997, pp. 273-287
A heat transfer tunnel used for local convective heat transfer coeffic
ient measurements on liquid crystal instrumented models is described.
The tunnel uses the new mesh heater device to produce a good approxima
tion to a step change in the test section flow temperature. A simple a
nalytical model of the cooling performance of cylindrical extended sur
faces is derived from empirical relations obtained from the literature
. Experiments conducted on a smooth cylinder and selected cylindrical
finned geometries are discussed. In the configurations investigated, t
he relative sizes of the fin diameter to the fin array greatly exceed
any geometries previously reported. The use of liquid crystal mapping
techniques is shown to provide the full distribution of local heat tra
nsfer coefficients across the fin surface. This enables a greater unde
rstanding of the convective cooling process than could be obtained fro
m the simple average measurements of h previously reported in the lite
rature. Existing finned tube correlations are shown to be unable to pr
edict the measured heat transfer levels. The investigation shows that
correct selection of fin geometry can result in a significant increase
in overall convective cooling performance.