Ryuji Ikeda

On abnormal change in loss coefficient of branch ducts within the subcavitating range.

Our previous report clarified the curvature effects on cavitation characteristics for right-angled branch ducts having corner radii of R/b=0, 0.25, 0.5 and 1.0, where R was the radius of the curvature and b was the width of the duct. The loss coefficient in branch side ξ13 was almost constant for R/b=0, 0.5 and 1.0, while ξ13 was not constant, but unexpectedly showed an abnormal change with respect to cavitation number σ1 for R/b=0.25. The purpose of this paper is to clarify such an abnormal change. Therefore, the present experiments wee conducted by changing R/b around 0.25 as 0.1, 0.2, 0.3 and 0.4. This abnormal phenomenon was observed in wide ranges of the curvature and the flow ratio, especially at a flow ratio K=1.0 and R/b=0.2. As a result, it is concluded that this phenomenon is principally related to the effect of fluid viscosity, not to cavitation.