COLUMN

PBCF was born from heavy and hard R/D works. Reverse Propeller Open Test (Rev. POT) has been thought up and utilized for the development, and this experimental methodology would be the key factor of the PBCF birth.
In this POT experiment, "Reverse POT" arrangement was used instead of normal POT to determine the influence of hub vortex more precisely. In this arrangement, the propeller driving shaft at the boss end was shifted to the upstream side.

The torque and thrust measurement of the propeller and the PBCF in propeller open-water test (POT) was carried out, and also significant torque decrease, thrust increase and the improvement of the propeller efficiency were obtained. (See figure upper right).

These papers introduce computational fluid-dynamics method (CFD) to be able to solve a hydrodynamic mechanism of PBCF behind a propeller.
CFD simulation has proceeded on the 5 bladed propeller in model scale and has given various and interesting knowledge.
The pressure distribution on the boss cap surface looking from aft is shown in Figure. High negative pressure appears on the center region of the boss cap for the case without PBCF.