过载下细小通道内自驱动气液振荡相变传热机理及载荷适应性强化

Phase change heat transfer of self-driven vapor-liquid oscillation in minichannel not only possesses a good energy and mass transport performance, but also shows a great potential for the overload adaptability, which provides an attractive candidate for the highly-efficient cooling of avionic device. Therefore, the project will fabricate a heat transfer device with embedded closed-loop microchannels, set up a centrifugal turntable for simulating the overload environment, and then carry out a visualization experiment of the self-driven vapor-liquid oscillating phase change heat transfer in minichannels. An unsteady theoretical model of vapor-liquid two-phase oscillating phase change heat transfer will be developed via lattice Boltzmann method and numerically simulated, in which the load effect, flow pattern evolutions and coupled evaporation-condensation phase change are considered. Through combining the visualization experiment and numerical simulation, the coupling thermodynamic and kinetic mechanisms of self-driven vapor-liquid oscillating operation, flow pattern evolutions and evaporation/boiling-condensation phase change heat transfer under overload will be revealed. The effects of overload intensity and load application mode on the self-driven vapor-liquid oscillation and phase change heat transfer are going to be expounded. The occurrence and critical conditions for the startup and heat transfer limit of the self-driven vapor-liquid oscillation under overload will be elucidated. In addition, the project will develop the method for the overload adaptability enhancement of the self-driven vapor-liquid oscillating phase change heat transfer in minichannels and fabricate the corresponding heat transfer device with strong overload adaptability. This project will be of significant scientific value in the theory development for the micro/mini-scale vapor-liquid two-phase flow and phase change heat transfer. It will also provide important technical supports for the development of cooling technology for avionics in the aircraft with high maneuverability.

细小通道内自驱动气液振荡相变传热不仅具有高效能质输运性能，更有着良好的过载适应性发展潜力，这为航空电子设备的高效冷却散热提供了一种有效途径。为此，本项目拟研制闭合回路细小通道传热样件，搭建离心式过载环境模拟转台，开展细小通道内自驱动气液振荡相变传热可视化实验；建立综合考虑载荷影响、流型演化及蒸发/沸腾-冷凝耦合的气液振荡相变传热格子Boltzmann非稳态理论模型并进行数值模拟。结合实验与数值模拟，揭示过载下自驱动气液振荡运行状态、流型演化及蒸发/沸腾-冷凝相变传热的热力学与动力学耦合机制，阐明过载强度、施载模式等对自驱动气液振荡相变传热的影响规律，掌握过载下自驱动气液振荡启动与传热极限的产生机理与临界条件，研发细小通道内自驱动气液振荡相变传热过载适应性强化方法与样机。本项目不仅有助于进一步完善微小尺度气液两相流动与相变传热基础理论，也将为高机动航空飞行器电子散热技术发展提供关键技术支撑。

本项目研制了一种双通道串联型板式自驱动气液相变传热样件，搭建了离心式过载环境模拟实验转台，建立了细小通道内自驱动气液脉动相变传热格子玻尔兹曼理论模型；结合实验观测与数值模拟，探明了过载条件下细小通道内自驱动气液两相的运行模式及其与相变传热机制间的内在联系，揭示了过载强度、施载模式等对流动与传热性能的影响规律，掌握了过载下自驱动气液振荡启动与传热极限特性。基于此，引入壁面烧结吸液芯并配合大小交替变截面通道结构设计，研发了过载适应性强化方法与传热样机。.研究结果表明：1) 过载条件下，随着热负荷的升高，细小通道内自驱动气液振荡行为以此呈现“停滞-启动”间歇式运行、持续脉动运行和循环运行；随着过载强度的升高，产生各类运行状态所需的临界热负荷增大；持续脉动运行下，强制对流蒸发-冷凝传热作用凸显，并直至循环运行时开始成为主导传热机制。2) 适当强度的顺载过载（≤3.0g0（g0=9.8m/s2））强化了管间压力分布与传播的不均匀性，有助于提升工质的启动速度与稳定性；侧载过载则始终不利于成功启动。3) 适当强度的顺载过载（≤2.0g0）促进了蒸发段的回流补液，有助于提升烧干极限。4) 顺载和侧载过载均会削弱“气泡泵效应”，进而降低细小通道内自驱动气液振荡相变传热性能，但侧向过载的负面影响更为明显；5) 载适应性强化样机具有良好的传热性能与载荷适应性：平均当量导热性能为6063航空铝合金的3.85倍；1g0~3.6g0载荷范围内，样件导热系数相对变化率≤29%。.基于以上研究成果，在International Journal of Heat and Mass Transfer、Energy Conversion and Management等权威期刊上发表SCI收录论文33篇，申请发明专利6项（已授权3项）；受邀做特邀报告2次；培养研究生5名；项目负责人获评江苏省工程热物理学会科学技术一等奖。

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