The aim of this research is to study the heat transfer characteristics on an internal surface of
rectangular wind tunnel by mounting pin array. The cylindrical pins which have diameter of D=10 mm
were arranged with inline and staggered configurations and were normal to flow direction inside wind
tunnel. The pin-to-pin spacing in streamwise and spanwise directions were varied at S/D=2, 4, and 6.
The pin height was varied at H/D= 1, 2 and 3. The Reynolds number of internal flow was fixed at
Re=30,000. The temperature distributions on the heat transfer surface were measured by using
Thermochromic Liquid Crystal sheet ( TLCs) , and Nusselt number distributions were evaluated by
using image processing technique. The results show that effect of pin height ratio (H/D) and pin-to-pin
spacing ratio (S/D) were more significant on increasing heat transfer. In case staggered arrangement,
heat transfer with low S/D and high H/D is the highest. The thermal performance that is equal to 1.08
is the highest at the case of H/D=1 and S/D=4 with inline arrangement.