A numerical study for the efficacy of flow injection

초록

cavitation due to the gap flow between fixed and movable portion of a horn type rudder system is not easy to avoid entirely. It is a common practice to attach a half round prismatic bar protruding beyond the concave surface of the horn facing the gap and laid along the centerplane of a rudder to lessen the gap flow, but employment of such an device does not always yield satisfiable results. Previously, the authors have shown that a pair of blocking bar attached on the convex surface of the movable portion gains an advantage over the single centre bar installed on the concave surface in enhancing the blocking ability of gap flows and circumventing the difficulties that might occur in practical applications. In the present study, it is shown through a series of numerical computations that flow injected into the gap of a rudder can also block the flow within, without employment of any physical divices such as a half circular bar. It is also shown that combination of flow injection and blocking bars may result in synergic augmentation of blocking efficiency of gap flow as demonstrated in computations for a three dimensional rudder system.