| With the intelligence of high-speed trains and the miniaturization of electrical equipment,1GBT is widely used as the main control unit of inverters.The IGBT controls the high-frequency turn-on and turn-off about the electric current,and a large amount of heat is generated during the period.How to release heat in time directly affects the stable operation of trains.The damage rate of IGBT is about 95%because of the excessive temperature of internal nodes.Therefore,it is particularly important to ensure that IGBT operates at normal temperature.With the increase of the power of power electronic equipment,the heat flux density has reached 100 W/cm2,and the traditional cooling technology can not meet the technical needs.In order to release IGBT heat efficiently and quickly,a heat sink with high heat dissipation performance is required.Aiming to improve the performance of the heat sink,the method of adding ribs in the heat dissipation channel was adopted.In this paper,a small-scale channel water-cooled radiator with isosceles trapezoidal ribs was studied.The radiator is composed of IGBT heat dissipation base plate(cold plate)and cover plate.The trapezoidal ribs are arranged transversely in the cavity formed by the two boards.The height of the channel is 2.5 mm,the bottom angles of isosceles trapezoids are 60°,700 and 80°,the ratios of height to width of isosceles trapezoids are 1,1.5 and 2,and the spacings of isosceles trapezoidal ribs are 0.4 mm,0.8 mm and 1.2 mm,respectively.Different geometric parameters are combined into different structures.In this paper,numerical methods are used to study the flow and heat transfer in small-scale channels.The fluid-solid coupling heat transfer model is adapted.The ICEM is used to mesh the channel calculation domain.The Fluent software is used to solve the calculation under the premise of ensuring the mesh quality.Selection of appropriate turbulence models by comparison of smooth channels.In the range of Reynolds number of 500?3300,the effects of different structural parameters of small-scale channel trapezoidal ribs on flow and heat transfer were studied,and the heat transfer performance of the channel was evaluated.The effects of different structures on the horizontal and vertical secondary flows were studied.The comparison with the smooth channels revealed mechanism of the enhanced heat transfer,and the correlations are fitted to the results under all parameters.The paper drew the following conclusions.It could be concluded that in the research range,the larger the aspect ratio and rib spacing of the trapezoidal rib,the better the heat transfer effect,but the greater the drag coefficient;the smaller the isosceles trapezoidal bottom angle,the better the heat transfer performance.The drag coefficient was larger.When the geometry of the trapezoidal rib was constant,as the Reynolds number increases,the heat transfer performance was better and the drag coefficient was smaller.The critical Reynolds number was around 1200.Enhanced heat transfer was enhanced under equal pumping and equal mass flow evaluation criteria.The water-cooled radiator water passed over the trapezoid and the lateral vortices,and longitudinal vortices generated at the same time improved the heat transfer performance of the radiator.In the research range,the larger the aspect ratio of the trapezoidal rib and the larger the rib spacing,the greater the intensity of the horizontal and vertical secondary flows.And the smaller the isosceles trapezoidal bottom angle,the greater the horizontal and vertical secondary flow intensity.The Nusselt number exhibited a certain relationship with the secondary flow.intensity,and the secondary flow intensity was used to characterize the heat transfer capacity.The heat flux in the main direction of the wall were transmitted in a convective manner,and the effects of the horizontal and vertical secondary flows effectively enhanced the transmission contribution of the local heat flux in the main direction on the wall. |
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