A cavitating flow around a single rotating wing is calculated and analysed using the finite differential method with the BTF (Bubble Two-Phase Flow) model as a cavitation model which has been developed in author's laboratory.
The Navier-Stokes equation and the continuity equation with the BTF cavitation model are used as governing equations. A cylindrical coordinate system fixed to the rotating blade is applied to simulate the flow around the wing.
A single fan-shaped wing are chosen as an object of the calculation because of its orthogonality in cylindrical coordination system that is the essential requirement of the finite differential calculation. The flow around a straight wing is calculated at the same time in order to compare its result with the rotating wing qualitatively.
The computed results of the rotating wing have significant difference from those of the straight wing in a place from where the cavity grows. In case of rotating wing, the cavity has aptitude to grow near the tip of the wing. Whereas in case of the straight wing, the cavity grows from the central part of the foil. The low pressure domain induced by the rotation causes this difference. On the other hand, a centrifugal effect of the rotating wing is verified by watching the secondary flow vector in the vicinity of the wing whose direction is outward.
While the rotating wing in this calculation is a very simple version of a marine propeller concerning the shape, the boundary conditions and the Reynolds numbers, this calculation method may develop to simulate the flow with cavitation around a real marine propeller with a fine grid and proper boundary conditions.