Experimental investigations of thermal and flow characteristics of curved trapezoidal winglet type vortex generators

The performance of a pair of new vortex generators - curved trapezoidal winglet (CTW) has been experimentally investigated and compared with traditional vortex generators - rectangular winglet, trapezoidal winglet and delta winglet using dimensionless factors j/j(0), f/f(0) and R = (j/j(0))/(f/f(0)). The results showed that delta winglet pair is the best in laminar and transitional flow region, while curved trapezoidal winglet pair (CTWP) has the best thermohydraulic performance in fully turbulent region due to the streamlined configuration and then the low pressure drop, which indicates the advantages of using this kind of vortex generators for heat transfer enhancement. Parametric study on CTWP showed that smaller attack angle (beta = 0 degrees = and 15 degrees), larger curvature (b/a = 1/2) and larger angle of inclination (alpha = 20 degrees) gives better thermohydraulic performance under the present conditions. An appropriate spacing between the leading edges of a pair of CTW VG should be considered for different flow regions. In addition, double rows of CTWP do not show better thermohydraulic performance due to the larger pressure drop and the spacing between the two rows of CTWP should also be optimized. (C) 2011 Elsevier Ltd. All rights reserved.