SUPERCAVITATING PROPELLERS, MOMENTUM THEORY
HYDRONAUTICS INC LAUREL MD
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Based entirely on momentum and other simple considerations a reasonably complete picture of the one dimensional pressure and velocity fields associated with heavily supercavitating propellers and drag discs was constructed. It is shown that the flow is very often retarded while approaching a heavily supercavitating propeller, so that the so-called ideal efficiency of such a propeller takes on values in excess of unity. The ideal efficiency actually increases with decreasing blade cavitational efficiency however, the net efficiency at the same time decreases. This retardation causes a reduction of thrust deduction, or even a change in its sign. Charts are provided from which the inflow speed may readily be estimated. The effect of water tunnel boundaries are discussed, particularly the phenomena of choking.
- Marine Engineering
- Fluid Mechanics