中文摘要：

为揭示微重力环境下加热表面尺寸对气泡动力学行为的影响,通过对比实验研究了不同热流密度条件下两种尺寸芯片表面核态沸腾过程中气泡的动力学行为.结果表明,低热流密度时两种尺寸芯片表面均能维持典型的孤立气泡沸腾,气泡生长合并过程缓慢,仅大芯片表面气泡脱落,并且体积达到小芯片气泡的3.4倍.两芯片在中等热流密度下均呈稳定的核态沸腾,气泡生长合并加速、脱离频率升高.大芯片表面气泡脱离次数明显高于小芯片,脱离气泡产生的尾流效应减小了后续气泡的脱离直径,进而有效抑制了气泡底部干斑的形成.高热流密度时,小芯片处于膜态沸腾状态,沸腾换热显著恶化;而大芯片表面仍能维较持稳定的核态沸腾.因此,增大芯片尺寸能有效促进气泡脱离,提高临界热流密度.继续升高大芯片热流至临界热流密度之上,虽然进入膜态沸腾换热状态,但是气泡无法完全覆盖芯片表面且可缓慢滑移,从而缓和了芯片温度上升速率.

英文摘要：

In order to study the influence of chip size on bubble dynamic behavior in microgravity, the factor of chip size on bubble dynamics under various heat fluxes has been studied by comparison experiments. Typical isolated bubble boiling maintains on both small and large size chips in low heat flux, and the growth and coalescence rates of bubbles are relatively slow. The volume of bubbleon large size chip is about 3.4 times that of the bubble on small size chip. The bubble departure could only be observed on the large chip during the experiment. Fully developed nucleate boiling are sustained in the case of moderate heat flux, the coalescence and departure frequency of bubbles is much higher than that in low heat flux, especially on large size chip. Bubbles detach more frequently on large size chip than that on small size chip. Moreover, the wake effect caused by bubble rising reduces the departure diameter of subsequent bubbles, so the formation of dry portions is effectively suppressed. For the high heat flux, obvious film boiling presents on the small size chip and the deterioration of heat transfer is observed. However, stable nucleate boiling still maintains on large size chip in the high heat flux, only the bubbles coalesce and detach more frequently. Therefore, increasing the chip size can effectively promote the bubble departure and improve critical heat flux. Film boiling is also observed as the heat flux on larger size chip is increased beyond the critical heat flux, but the heating surface could not be completely covered by the bubble, just sliding slowly on the slip, which can reduce the rising rate of temperature on chip effectively.