楔形夹缝内部液体核态沸腾特性

针对楔形夹缝内部液体核态沸腾状况进行可视化实验研究。实验利用表面平整均匀的铜板作为加热平板,用玻璃作为盖板形成楔形夹缝。实验现象表明沸腾核化现象比较容易在狭缝中相对较大的空间中形成,而在狭缝中相对较小的空间里形成沸腾需要更高的热流密度。实验现象还表明,在同一空间尺度条件处的核化和气泡演化情况基本相同,气泡的生长速率在无量纲参数D≥0.1时受到空间尺度的明显影响。 

Nucleation Boiling Characteristics of Liquid in Wedged Gaps

An experimental investigation was conducted to visually observe nucleate boiling phenomena in wedged gaps.A flat and uniform copper plate was used as a heater.The surfase of copper plate was ground by polishing method in order to reduce rugosity.A glass plate was used as a sheet for forming a wedged gap in the experiments.Ethanol was the object for observing and measuring.The phenomena showed that boiling nucleation favorably occurs and bubble growing is faster in areas with larger space in narrow gaps.The nucleation on the surface in relatively narrow zone was more difficult and needed higher heat flux than that in larger space zone.Images and figures shot by CCD camera were used to record bubble growth processes.It is observed that nucleation and bubble dynamical evolution in the same gap spacing zone are identical and the growth rate was maintained at a constant value for ≥0.1.