【摘要】 射流冷却是高热流密度换热的有效方法之一,射流尺度及热沉结构均对换热性能产生显著影响。本文对一种微小单锥体热沉结构,采用Realizableκ-ε湍流模型对热沉表面流动及换热特性进行研究,并进行实验验证。结果表明:在本文研究范围内(锥体直径为5 mm,锥体高度h分别为5 mm、7.5 mm和10 mm,射流雷诺数Re_j分别为2000、4000、6000、8000),在锥体附近产生环形的带状区域。Re_j对区域半径影响显著,当Re_j分别为2000、4000、6000、8000时,对应的区域半径分别约为5 mm、12 mm、18 mm、23 mm。根据流动结构和压力分布特点,单锥体热沉表面可分为四个区域,分别为驻点区、斜掠区、折冲区和附壁射流区,锥体热沉局部努塞尔数与局部压力系数分布相对应.与h=5mm和h=10 mm的热沉相比,当h=7.5 mm时热沉对流换热效果较好,平均努塞尔数可提升3.4%~6.2%,在h=7.5mm、Re_j=8000的情况下,当热流密度小于0.192~0.324 MW/m~2时,锥体热沉可对热源实现有效散热。更多还原

【Abstract】 Jet cooling is one of the effective methods to transfer the great flux density heat, both the jet scale and the structure of heat sink have significant effect on the performance of heat transfer. The result of surface flow and heat transfer characteristics of small single cone heat sink proposed in this paper is simulated by using the Realizable κ-ε turbulence model, which is varified by experiments.In this study, the cone diameter value is 5 mm, the cone height values(h) are 5 mm, 7.5 mm and10 mm respectively, and the injection Reynolds number values(Re_j) are 2000, 4000, 6000 and 8000 respectively. The results show that the Reynolds number has a significant effect on the radius of looping region in the area near the cone, the radius values are about 5 mm, 12 mm, 18 mm and 23 mm when the values of Re_j are 2000, 4000, 6000 and 8000 respectively. According to the characteristics of flow structure and pressure distribution, the couping surface of the heat sink can be divided into four zones, stagnation zone, scour zone, baffling zone and wall attachment jet zone in radial direction. The distribution of local Nusselt number is matching with the local pressure coefficient distribution. As average Nusselt number could be increased from 3.4% to 6.2%, the heat sink which cone height value is 7.5 mm has better performance on heat transfer in comparison with heat sinks which values are 5 mm and 10 mm. In the case of Re_j=8000, when the heat flux is less than 0.192~0.324 MW/m~2, the heat from the heat source could be effectively dissipated by the cone heat sink with h=7.5 mm.更多还原