Patent ID: 8381802

Claim:
A heat transfer device comprising: a linear or tubular heat transfer object in heat transfer contact with a heat carrier fluid, the heat transfer object having a rear end portion, a heat transfer fin which is formed integrally with the heat transfer object for heat transmission between the fin and the heat transfer object, and a plurality of longitudinal vortex generator winglets on the fin, each of which causes the fluid in vicinity of the heat transfer object to be conducted to a separation wake zone behind the heat transfer object for reducing the separation wake zone, each of which generates a longitudinal vortex behind the winglet, and each of which has a rear end; the plurality of winglets being arranged in a spanwise direction on each side of the heat transfer object, wherein the winglets on each side are positioned parallel to each other for deflecting the fluid to the same direction and conducting the fluid to an area behind the heat transfer object; wherein each of the winglets has a delta profile gradually decreasing in its height toward an upstream side of a flow of the fluid so that the longitudinal vortex is produced by the fluid flowing rearward beyond the winglet; wherein adjacent winglets located on the same side of the heat transfer object are partially overlapped: in a spanwise direction in a range of ⅓-⅔ of the winglet as seen from the downstream side of the flow so as not to cause interaction between the longitudinal vortices generated thereby, as seen from the lateral side of the flow, and as seen from the downstream side of the flow; wherein the rear ends of said winglets are located in stepwise offsetting positions toward the heat transfer object and in a streamwise direction of the flow, and the rear end of the winglet closest to said object is placed in a lateral position or on upstream side with respect to a rear end portion of the heat transfer object; and wherein an attack angle of said winglets with respect to a streamwise direction of said fluid is set to be a predetermined angle in a range from 10 degrees to 45 degrees.