| 摘要 |
PURPOSE:To decrease the resistance loss of a flow by introducing and rectifying the flow in a streamline, as well as to enhance the heat transferring effect of the surfaces of fins, by mainly utilizing the effect of the front edges of fins, and by arranging the fins in a row in series, vertically next to its row along the fow line, on a different streamline from each other. CONSTITUTION:A fin is divided into twelve pieces of finlets 11, 12, 13, 14, 15, 16, 16', 15', 14', 13', 12', and 11' per one winding around the outer periphery of a tube. The finlets are bent in a circular arc. An projected finlet and a recessed one are alternately arranged. The tangential angles of their front and rear edges to the surface at right angles with the axis of a tube are determined as + or -theta. The heating medium flowing outside of the tube proceeds in zigzag, in front and in the rear among the rows of finlets. During that time, heat is exchanged by the surfaces of finlets of which heat transferring efficiency is very high, by the effect of the front edges of fins, and by division of each flow line, turning of directions (introduction of flow), mixing of thinness and denseness, and confluence of the flow. Besides, the pressure loss in the flow path is comparatively small by the rectifying action of the finlets. In order to decrease the resistance to the front and the rear edges of a tube against the flowing direction at right angles with the axis of a tube, the roots of finlets 11, 11', 16, 16' in the corresponding positions are bent as shown in 21, 21', 26, 26' to cover the distances of the front and the rear of the fins, so that the flow is introduced in a streamline to the direction at right angles with the axis of a tube. |
