Heat transfer adjacent to the attached end of a cylinder in crossflow

Wind-tunnel experiments were performed to determine heat-transfer coefficients in the region of wall-cylinder interaction for a wall-attached cylinder in crossflow. Quasi-local transfer coefficients were measured with a small (one-quarter-diameter-long) disklike sensing element positioned at various axial stations along the cylinder. The experiments spanned the Reynolds number range from 3500 to 23,000 and were supplemented by velocity-profile measurements and flow visualization. It was found that the wall-cylinder interactions were confined to a length of the cylinder extending about one diameter from the wall. In the interaction region, the quasi-local coefficients were lower than those in the wall-unaffected region. The decreases were accentuated with decreasing distance from the wall, but this trend was reversed in the immediate neighborhood of the wall due to the presence of a compact, vigorous vortex. The largest decrease was in the 15 percent range, while the average decrease for the entire wall-affected region was about 9 percent.