Kondratyuk V. Heat transfer and aerodynamics of flat-oval tube banks in the cross flow

Dissertation is devoted to solving the actual problem of the development of scientific bases of creating a new type of heat transfer surfaces from the flat-oval tube banks, the implementation of which leads to significant savings in material and energy resources. Comprehensive experimental and numerical study of heat transfer and aerodynamics of single flat-oval tubes and its staggered banks were carried out in the range of values of the geometrical and operational characteristics important for applications. It is shown that the use of these tubes in heat exchangers at the cross flow is expedient through increase of the heat exchange intensity and reduce of the aerodynamic drag. Methods of complete thermal simulation, surface flow visualization and CFD modeling were applied. The results of image and numerical studies on the basis of which are disclosed features of the transfer mechanisms in the cross flow of flat-oval tubes are shown. According to the results of studies in a wide range of geometrical characteristics of d2/d1, S1/S2, H/F their impact on the heat transfer rate and the aerodynamic drag of the flat-oval tube banks was determined. It is shown an ineffectiveness of dimple intensifiers on the sides of flat-oval tubes. The techniques of thermal and aerodynamic calculation of staggered flat-oval tube banks were offered. Computational and engineering development of new type series of regenerators-air heaters for GTU of gas compressor unit GCU-10 was made on the basis of the offered techniques.