翼端渦の解像を考慮したCFDによるプロペラキャビテーションの数値シミュレーション

摘要

Marine propellers are operating in the unsteady ship wake flow, which causes the repeat of cavitation occurrence and disappearance. Such cavitation causes the serious vibration and erosion problems. Therefore, the decrease of the erosion risk is one of the very important issues in the propeller design. Especially, latest propeller design for high efficiency is based on detail estimation of cavitation performance. It is necessary to estimate the process of cavitation disappearance related to both blade cavitation and tip vortex cavitation near the very local tip region for the evaluation of the erosion risk.rnRecently, RANS method becomes the common useful design tool for the analysis of the flow field around marine propellers, and the application to the cavitation simulation is highly expected. It is thought that it becomes an effective method for the evaluation of the erosion risk, if it may simulate the blade cavitation and the tip vortex cavitation in detail.rnFirst of all, numerical simulation of the tip vortex of the DTMB P4119 propeller in non-cavitating condition was performed in order to examine the effectiveness of the adaptive mesh generation. Numerical results of flow field behind the propeller were compared with LDV measurement results.rnFinally, the cavitation simulation including tip vortex for Seiun Maru -I propellers was performed by and the cavitation patterns were compared with the experiments.%プロペラが船後の不均一な流れの中で作動するために、プrnロペラ周囲で、キャビテーションが発生・消滅を繰り返し、rn船尾振動、エロージョンなどの深刻な問題を引き起こす。rnエロージョンリスク低減のために、十分大きい翼面積を採rn用し、キャビテーションの発生面積を減らすことが有効であrnることが、経験上分かっている。また、キャビテーションのrn発生範囲の大小は種々の理論計算で捉えることが可能であrnり、キャビテーションの発生範囲を設計段階で調整することrnもある程度可能である。