ISSN Online: 2377-424X
International Heat Transfer Conference 12
Experiments on convective heat transfer of air-flows at low Reynolds Number through wavy and grooved channels
Resumo
This paper presents experimental data on heat transfer coefficients and pressure drops of air-flows at Reynolds
number ranging between 500 and 7000 inside a wavy channel and two grooved channels. Data for a plain
channel are also reported for comparison. All channels have a rectangular cross-section with ribs or grooves
perpendicular to the streamwise direction; the channel height is 15 or 18 mm. The wavy channel is characterized
by triangular cross-section ribs spaced by flat strips, which alternate staggered on the lower and upper walls; the
other two channels have grooves only on the lower wall with an aspect ratio of 1:1 and 2:1, respectively. Local
heat transfer characteristics are investigated by non-intrusive measurements of velocity and temperature fields by
means of LDV and holographic interferometry; data on average coefficients and pressure drops are also reported.
Data for Re≤2000 are compared to the results of direct numerical simulations obtained by means of a CFD
commercial code. For the wavy channel, the heat transfer enhancement is quite small (20%) within laminar
regime while it becomes a quickly increasing function of Re for values greater than 1300; however, pressure
drops also start to steeply increase. The grooved channels are characterized by a poor enhancement (30%) but
without significant penalization in pressure drops.