Abstract

This article presents the results of experimental studies of the efficiency of heat transfer under conditions of intense fields of mass forces on a flat rectangular (\(16 \times 24\) mm²) heat-transfer surface (HS) modified by additive manufacturing. A porous sinusoidal-form coating consisting of spherical bronze granules of average diameter of 35 \(\mu\)m was 3D printed on the brass base of the heat-transfer unit. The thickness of the coating was 150 \(\mu\)m in the deepenings and 300 \(\mu\)m on the ridges. Comparative experimental studies were carried out on an unmodified HS and modified HS in liquid nitrogen under conditions of centrifugal accelerations of up to 4090 g. The heat transfer was studied in the range of heat flux densities of \(4 \cdot 10^{4}{-}8.9\cdot 10^{5}\) W/m². It has been shown that in the range of heat flux densities of \(80,000<q< 320,000\) W/m², increase in the intensity of the mass force fields leads to growth in the heat transfer coefficient up to 4 times at transition from the developed boiling regime to the single-phase convection regime. In the region of developed boiling, for the heat flux density range corresponding to a given overload, the heat transfer coefficient normalized to the value of the heat transfer coefficient calculated as per the Borishansky relation for these conditions decreases with increasing centrifugal overload. The dependence of the relative heat transfer coefficient on the overload is close to the ratio \(\alpha_{\rm s}/\alpha_{\rm sB} \sim \eta^{-1/6}\).

中文翻译：

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低温恒温器高速旋转强质量力条件下毛细管多孔涂层氮气沸腾过程中传热的增强

摘要

本文介绍了在通过增材制造改性的扁平矩形 ( \(16 \times 24\)  mm ²）传热表面 ( HS ) 上的强质量力场条件下传热效率的实验研究结果。在传热单元的黄铜底座上 3D 打印出由平均直径为 35 µm 的球形青铜颗粒组成的多孔正弦形涂层 。涂层厚度 在加深处为 150 μm， 在脊部为 300 μm 。对未修饰的HS和修饰的HS进行了对比实验研究在液氮中，离心加速度高达 4090 g。研究了热流密度 \(4 \cdot 10^{4}{-}8.9\cdot 10^{5}\)  W/m ²范围内的传热。研究表明，在热流密度 \(80,000<q< 320,000\)  W/m ^2范围内，质量力场强度的增加导致从发达的沸腾状态过渡到单相对流状态时传热系数增长高达 4 倍。在发展沸腾的区域中，对于与给定过载相对应的热流密度范围，归一化为根据这些条件的Borishansky关系计算的传热系数值的传热系数随着离心过载的增加而减小。相对传热系数对过载的依赖性接近于比率 \(\alpha_{\rm s}/\alpha_{\rm sB} \sim \eta^{-1/6}\)。