Flow Drag Reduction And Cooling Characteristics Of Nanofluids In Bionic Electronic Component Heat Sinks

With the development of technological society,the use of electronic products is increasing,and while achieving a high level of integration,it also brings an increase in the heat generation inside electronic components.In order to reduce the heat loss of electronic components,many scholars have replaced the traditional heat transfer medium with nanofluids.Although this can better enhance heat transfer,it also increases the flow resistance inside the fluid,thus increasing energy consumption.From this perspective,referring to the drag reduction principle of shark shield scale structure in bionics,the flow resistance and cooling characteristics of micro electronic components were investigated by numerical simulation and experimental research,and the main research contents are as follows:（1）In this thesis,Fe₃O₄-H₂O nanofluids with different concentrations were prepared.The shark shield scale structure was abstractly extracted and a bionic enhanced structure cooling system with different heights,opening angles,spacing distances and arrangement modes was designed.A cooling system test bench was built to study the effects of bionic reinforced structure and nanofluids mass fractions on the flow resistance and heat transfer effect of the cooling system,and the thermal-hydraulic performance of the cooling system was evaluated by the comprehensive evaluation index.Results indicated that the Nussle number of the cooling system increases first and then decreases with the increase of nanofluids mass fraction,and when the mass fraction of Fe₃O₄-H₂O nanofluids is 0.3%,it shows the best comprehensive performance.（2）In the experimental study stage:Firstly,two groups of six structures were designed with ordinary symmetrical V-grooves,and the conclusion that the comprehensive performance was optimal at an opening angle of 53°and a groove height of 2 mm was obtained.Therefore,with reference to the conclusion,the adjacent shark shield scale bionic structure and the spaced shark shield scale bionic structure（total 5 groups of 15 structures）were further designed.The experimental results showed that compared with the ordinary symmetrical V-grooves with a single size structure,the new bionic grooves with different heights,different angles and different spacing arrangements are closer to the real shape of shark shield scales,and their flow drag reduction and heat transfer effects are better.Comparing all the bionic grooves horizontally,it was found that the bionic grooves with better cooling characteristics have weaker flow drag reduction performance,among all the bionic strengthening structures,the spacing shark shield scale grooves with different angles have the best comprehensive performance.（3）In the simulation stage:the physical model of spaced shark shield scale grooves with different angles was established based on the experimental results,and the pressure cloud,trace,velocity vector,temperature cloud and wall shear stress on the surface of the grooves during the longitudinal and transverse flow were analyzed.Results showed that the"secondary vortex"with opposite directions appears at the top of the longitudinal groove,and the"secondary vortex"reduces the frequency and intensity of turbulent burst,thus weakening the surface turbulence intensity.The existence of vortex clusters enhances the disturbance to the heat transfer medium.The existence of vortices destroys the laminar flow boundary layer,and also enhances the heat transfer effect while playing a drag reduction effect.Small size vortices appear at the bottom of the transverse groove in the same direction as the fluid flow above,and each vortex is stable at the bottom of the groove and does not spread outward.The low-speed vortex separates the wall from the flowing medium,and the fluid flows over the vortex,changing the sliding friction into rolling friction,which is similar to a"rolling bearing",thus reducing the flow resistance,and the vortex also enhances the disturbance to the heat transfer medium,and at the same time enhances its heat transfer effect.There are 10 tables,68 figures and 114 references in this thesis.