Abstract A detailed experimental investigation of the heat transfer and fluid flow characteristics of finned surfaces was conducted for airflow ( Re L = 6250–25,000) at a flat plate boundary layer and narrow duct corresponding to 200 mm and 20 mm duct height, respectively. Short rectangular fins of either aluminum or resin material were attached in 7 × 7 arrays to a heating surface and the fin height, inclination angle and fin pattern (co-angular and zigzag) were varied. The fin spacing to length ratios along the streamwise and spanwise directions were kept at S x / L = 2 and S z / L = 1, respectively. T-type thermocouples and an infrared camera with a 160 × 120-point In–Sb sensor were used to measure the wall temperature and the detailed heat transfer at the endwall along with fin base. Dye flow in a water channel and titanium oxide oil film flow patterns around the fins were observed to study the flow behavior and its effect on heat transfer. In case of co-angular pattern flow stagnated in front of the fin and formed a strong horseshoe vortex around the fin while the longitudinal vortexes generated by the side top edges touched the fin surface and the endwall. On the other hand in case of zigzag pattern a weak horse shoe vortex appeared in front of the fin while the longitudinal vortex struck the endwall mainly and a sinusoidal wavy flow behavior was observed. The friction factor value was found to be almost constant and somewhat larger for a zigzag pattern of fins than for a co-angular pattern. The heat transfer results show that a narrow rectangular duct of 20 mm height with fin arrays in a zigzag pattern is the most effective, exhibiting a heat transfer enhancement at the endwall of more than four times over the case without fins wherein co-angular is the least recommended as it exhibits enhancement about a factor of more than three times. At flat plate boundary layer, i.e. in tall duct case both co-angular and zigzag patterns show almost same overall heat transfer enhancement about a factor of three times over the case without fins.
[1]
C. Herman.
Experimental Visualization of Temperature Fields and Measurement of Heat Transfer Enhancement in Electronic System Models
,
1994
.
[2]
E. Sparrow,et al.
Enhanced and local heat transfer, pressure drop, and flow visualization for arrays of block-like electronic components
,
1983
.
[3]
Kenyu Oyakawa,et al.
The Effects of the Channel Width on Heat-Transfer Augmentation in a Sinusoidal Wave Channel
,
1989
.
[4]
Ephraim M Sparrow,et al.
Heat transfer and pressure drop characteristics of arrays of rectangular modules encountered in electronic equipment
,
1982
.
[5]
Cila Herman,et al.
Experimental visualization of temperature fields and study of heat transfer enhancement in oscillatory flow in a grooved channel
,
2001
.
[6]
Mohammad Faghri,et al.
A Correlation for Heat Transfer and Wake Effect in the Entrance Region of an In-Line Array of Rectangular Blocks Simulating Electronic Components
,
1995
.
[7]
Ephraim M Sparrow,et al.
Transfer characteristics of two-row plate fin and tube heat exchanger configurations
,
1976
.
[8]
A. Turk.
HEAT TRANSFER ENHANCEMENT DOWNSTREAM OF VORTEX GENERATORS ON A FLAT PLATE
,
1986
.
[9]
A. M. Abdel-latif,et al.
Investigation of turbulent heat transfer and fluid flow in longitudinal rectangular-fin arrays of different geometries and shrouded fin array
,
2002
.
[10]
G. J. Vanfossen.
Heat transfer coefficients for staggered arrays of short pin fins
,
1981
.
[11]
T. Igarashi.
Local heat transfer from a square prism to an airstream
,
1986
.
[12]
Ryosuke Matsumoto,et al.
Effect of Pin Fin Arrangement on Endwall Heat Transfer
,
1996
.