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The problem of improving heat transfer surfaces made in the form of the bundles of transversely finned tubes remains very pressing. Studying the works, devoted to this problem, and a number of patents, including patents of the USA, Great Britain, Germany, and Japan, revealed that the ways of increasing thermoaerodynamic efficiency of the transversely finned surfaces mainly involve a search for the most rational types of finning and arrangement of the finned tube bundles. A great many works on developing intensified surfaces are associated with setting up conditions for the breakdown of thickened boundary layers on relatively high fins and for the organization of a developed vortex flow, if possible, over the entire surface. Such conditions are attained by corrugation of the transverse fins (Tolubinskiy & Lyogkiy, 1964), their perforation (Migai et al., 1992; Eckels & Rabas, 1985), cutting into short sections with ends bent to the opposite sides (Taranyan et al., 1972; Sparrow & Myrum, 1985) and with the use of the so-called segment finning. Analyzing these developmental works and related investigations allows us to note the following. The fin corrugation leads to a noticeable augmentation of heat transfer, but the heat enhancement is accompanied in this case by a still more noticeable increase of the aerodynamic drag: by data (Tolubinskiy & Lyogkiy, 1964), the replacement of smooth fins on a single finned cylinder by corrugated fins at Re = 104 enhances heat transfer by 12-15% with a drag increase by 65-70%. This circumstance, in conjunction with a difficult manufacturability of the tubes with corrugated fins, renders their wide use problematic. The literature offers ample coverage of the results for thermoaerodynamic characteristics of bundles of tubes with cut fins (Taranyan et al., 1972; Kuntysh & Iokhvedov, 1968; Antufiev & Gusyev, 1968; Iokhvedov et al., 1975; Antufiev, 1965) (Fig. 1). Such heat transfer surfaces are fabricated from the tubes with a typical helical finning by cutting the fins into short sections by a thin mill along the generatrix of a carrying cylinder or along a helical line at an angle of 45o. Cutting does not practically diminish the fin surface and, according to data of the above-mentioned works, enhances heat transfer by 12-36% depending on the fin parameters and the method of cutting fins. The effect of flow turbulization, produced in this case, is the more appreciable, the higher are the cut fins. However, in all cases an increase in aerodynamic drag markedly outstrips an increase in heat transfer which on the whole noticeably reduces the total effect of heat transfer enhancement. Besides, the production of tubes with cut fins requires additional technological operations, which, in conjunction with

Enhancement of Heat Transfer in the Bundles of Transversely-Finned Tubes