Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : November 11, 2020 - November 13, 2020
Bubble drag reduction (BDR) is expected as a solution to ship energy saving. However, it has a problem that the combination of bubbles at aft disturbs the drag reduction. This study aims to development of bubble splitter to make bubbles fragmented without external force for superior performance by BDR. We designed three types of protrusions as bubble splitters and examined their performance in a gas–liquid two-phase channel flow through observation of a downstream region of the bubble splitters. The bulk speed in channel flow was about 1 m/s. We also conducted an experiment with surface active agent to consider effects of the size of the splitters. Unfortunately, bubbles did not fragment enough with nor without surface active agent and it led to the conclusion that the bubble splitters do not work in the flow. However, the large air film right downstream from the device was a finding which is expected to enhance performance of gas layer drag reduction or gas cavity drag reduction.
