Baskova O. Management of vortex heat and mass transfer in the elements of power equipment

The dissertation is devoted to the study of the influence of surface geometry, the value of the Reynolds number and non - isothermal conditions in the wall region on the energy efficiency of the initial sections of tubes with corrugated inserts in the transient flow regime. The generation and development of perturbations in a flow and their effect on heat transfer processes in a wide range of Reynolds transition numbers were investigated. It is found that at a certain ratio of dimensionless lengths and amplitudes of the surface waves, related to the radius of the tube, corrugated inserts can be both flow stabilizers at the initial section of the pipe and generators of low-frequency perturbations at the corresponding Reynolds number, which leads to heat transfer. It is shown that the energy efficiency of tubes with corrugated inserts of the "non-cluttering" type can be determined only by the ratio of Nusselt numbers in the tube with corrugated insert and in the smooth tube, due to the fact that the additional resistance of the tube with corrugated insert of "non-cluttering" type does not exceed 7%, in contrast to corrugated inserts of the "cluttering" type, where additional hydraulic resistance exceeds 15%. The threshold values of the corrugation wavelength and the corresponding amplitude, the corrugation angle of inclination to the tube axis, and the length of the corrugated section are determined for a certain value of the Reynolds number at which the highest energy efficiency of the corrugated insert is achieved.