FLOW AND HEAT TRANSFER IN LOUVERED AND OFFSET-STRIP FIN ARRAYS: THE EFFECTS OF VORTEX SHEDDING AND BOUNDARY-LAYER RE-STARTING

Data from offset-strip and louvered fins are used to explore vortex shedding and boundary-layer re-starting effects on heat exchanger performance. Both mechanisms are important to offset-strips, but only boundary-layer effects are important to louvers. The shedding structure in irregular arrays vitiates the expected heat transfer impact. Unless the effects of array regularity on vortex structure are understood, strategies for enhancing offset-strip fin arrays should focus on shedding, and louver enhancements should exploit boundary-layer thinning.