Numerical investigation of cooling down and aerodynamic resistance processes in ribbed tubular elements

The improvement of technological processes determines the requirement to increase the energy efficiency of heat exchange devices and leads to the essential complication of heat removal surface geometry. One of the most common types of convective heat exchange device elements is bundles of ribbed tubes; however, there are no unambiguous dependencies for estimating their thermal efficiency and aerodynamic drag. This paper presents the results of a numerical study of the cooling down and aerodynamic resistance processes in a single ribbed tubular element when the heat exchange device is operating in extreme modes. To solve the conjugate problem of external aeromechanics, internal hydrodynamics, and heat transfer within models of heat-conducting viscous compressible gas and incompressible fluid, the chtMultiRegionSimpleFoam solver is used that belongs to the open integrable platform for the numerical solution of flow mechanics problems. The specific topological features of implemented modes of gas flow around the ribbed element are revealed and described. The influence of the gas-dynamic flow background on characteristics of the gas / tube / liquid heat transfer process and of the character of the gas flow near the ribbed tubular surface on parameters of the boundary layer formed in the coolant flow is shown. The dependence for determining the thermal gradient for a single gas passage through a heat exchange device with one tube is obtained and presented. For the first time, a generalized temperature profile in the rib longitudinal section is obtained by mathematical modeling.