Based on predictions of lower pressure drop penalties in fractal-like branching channels compared to parallel channels, an experimental investigation of two-phase void fraction variations was performed. The flow network, mimicking flow networks found in nature, was designed with a self-similar bifurcating channel configuration and etched into a 38.1 mm silicon disk. A Pyrex cover was anodically bonded to the silicon disk to allow for flow visualization. The length and width scale ratios between channels on either side of a bifurcation are fixed. The channel widths range in size from 100 (mu)m to 400 (mu)m over a total channel length of approximately 17 mm. The experimental study of flow boiling in the fractal-like heat sink was performed for two energy input levels of 61 W and 66 W and two flow rates of 45 g/min and 50 g/min. The inlet fluid temperature was held constant. High-speed, high-resolution imaging was used to visualize flow regimes and quantify void fraction variations in several channels within the branching structure, using water as the working fluid. Both time-averaged and instantaneous images are presented, showing correlation effects between channels in different levels and between channels in the same level.
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