Abstract
Injection of microbubbles within water has been investigated for several years as a method to achieve pipe friction loss reduction. However, the physical mechanism of this phenomenon is not yet understood. So, the purpose of our study is to understand the mechanism. We researched pipe friction loss reduction by the experimental device, which was constructed by a circular pipe. Adherence of bubbles to the wall had an effect on pipe friction loss. In the case of void fraction 0.1% ± 0.02%, the effect was shown Re ≦10000, and influenced pipe friction loss reduction. In addition, in the event Re = 5000, 20000, pipe friction loss reduction became enlarged by increasing void fraction. Meanwhile, at Re = 10000, pipe friction loss reduction didn't change widely by increasing void fraction. As the result, void fraction had a relationship with pipe friction loss.
