湍流通道散热器结构拓扑优化方法研究

With the increasing heat dissipation of electronic equipment, the heat dissipating problem has become a key factor restricting its development. The turbulent-flow channelled heat sink (TCHS) is a kind of important heat sinks for electronic equipment whose heat dissipating principle is the turbulent flow heat transfer problem with temperature-dependent thermophysical properties. The topology optimization method can greatly enhance the performance of TCHS. However, most of the existing topology optimization methods are based on laminar heat transfer model with constant thermophysical properties. Few topology optimization methods have been proposed for the turbulent flow heat transfer model with variable thermophysical properties because of the difficult problems of the numerical stability and the global optimization performance caused by the strong nonlinearity of the model. Therefore, the present method is difficult to realize precise topology optimization of TCHS’s structure. This project intends to propose a k-ε type Reynolds time-averaged turbulence model based unified equivalent method for establishing a stable topology optimization model; develop a continuous adjoint sensitivity analysis technique for the coupled turbulent flow heat transfer field with variable thermophysical properties, to explore and reveal the topology optimization mechanism and parameter influence mechanisms of turbulent flow heat transfer with temperature-dependent thermophysical properties; propose a global adaptive implicit function method with no gray area, high precision and better global performance for implementing topology optimization of the turbulent flow heat transfer problem with temperature-dependent thermophysical properties; and obtain the topology optimization method for the turbulent flow heat transfer problem with temperature-dependent thermophysical properties. This research provides theories and methods for achieving the precise topology optimization of TCHS’s structure, which is of great significance to ensure the safe and efficient operation of electronic equipment.

随着电子设备热量耗散不断增大，散热问题已成为制约其发展的关键因素。湍流通道散热器是一种重要电子设备散热器，其散热原理是温度依赖变物性湍流传热问题，拓扑优化方法可实现其性能的大幅度提升。然而，现有拓扑优化方法多基于常物性层流传热模型，由于强非线性造成的数值稳定性和优化全局性难题导致尚缺乏变物性湍流传热模型的拓扑优化方法，难以实现湍流通道散热器结构精确化拓扑优化。本项目拟通过提出基于k-ε雷诺时均湍流模型的统一化等效法，建立稳定化拓扑优化模型；发展变物性湍流传热耦合场的连续伴随灵敏度分析技术，探究并揭示温度依赖变物性湍流传热拓扑优化机理和参数影响机理；提出执行变物性湍流传热拓扑优化的无灰度区域、高精度且全局性较好的全局自适应隐函数法；获得解决温度依赖变物性湍流传热问题的拓扑优化方法。本研究为实现湍流通道散热器结构精确化拓扑优化提供理论和方法，对保障电子设备安全高效运行具有重要意义。

电子设备耗散热量和热流密度的不断增大，使得散热问题成为制约其发展和应用的关键因素。湍流散热器可以实现电子设备较高效率的散热，在工程领域具有广泛应用，拓扑优化方法可大幅提升其性能。现有拓扑优化方法多基于常物性层流传热模型，研究基于变物性湍流传热模型的拓扑优化方法能够得到符合实际传热现象且性能更加优异的设计结果，是实现湍流散热结构精确化拓扑优化的必要手段。然而，由于变物性湍流传热模型的强非线性会造成数值求解稳定性和优化全局收敛性等方面的难题，因此基于该模型的拓扑优化研究较少，制约了湍流散热结构的设计创新。.针对上述难题，本项目开展了温度依赖变物性对流传热、湍流流动、湍流强制和自然对流传热等问题的拓扑优化研究，取得了以下重要结果。1) 发展了基于k-ε湍流模型的统一化等效方法，构建了湍流流动问题的稳定化拓扑优化模型；发展了基于k-ω湍流对流模型的统一化等效方法，构建了湍流强制和自然对流传热问题的稳定化拓扑优化模型。2) 发展了耦合场联立式离散伴随灵敏度分析技术，分别揭示了温度依赖变物性层流对流传热、湍流流动、湍流强制和自然对流传热等问题的拓扑优化机理。3) 发展了一种分离式迎风有限元算法进行湍流强制和自然对流传热控制方程的数值求解，以降低内存使用量和提高数值求解速度。4) 运用变密度方法分别实现了变物性纳米流体层流对流传热、湍流流动、湍流强制和自然对流传热等问题的拓扑优化；5) 探究并揭示了物性参数、流动状态、固体导热系数和纳米流体特性参数等对最优设计结果的影响机制。.本项目研究工作为实现湍流散热结构质轻紧凑和高效节能的创新性设计提供理论和方法依据，对保障电子设备安全高效运行具有实际意义。