PRODUCT SOLUTION

Neighbor Duct

Generating Thrust Using Bilge Vortices

The Neighbor Duct is an energy-saving appendage designed to reduce hull resistance by generating forward thrust through the flow that runs along the side of the hull. It features a vertically elongated elliptical shape and is a completely new type of stern duct installed near the ship’s stern.
The Neighbor Duct is designed based on a combination of ship hull data and model test results, such as self-propulsion tests with a bare hull and measurements of hull resistance and wake distribution.

Neighbor Duct Design Process

Using hull geometry data, CFD analysis is performed to observe the flow lines around the bare hull condition. A parameter survey is then conducted for duct width, angle of attack, and installation position to determine the optimized duct shape. Further CFD-based self-propulsion calculations are carried out to assess changes in self-propulsion factors and to examine detailed fluid phenomena such as longitudinal vortex behavior, completing the design process.

Validation of Energy-Saving Effects on Actual Vessels

In a joint study with the National Maritime Research Institute of the National Institute of Maritime, Port and Aviation Technology (Japan), self-propulsion tests using a model of an 82BC vessel confirmed a 4.7% reduction in required shaft power.
Notably, the improvement in thrust deduction factor was significant, verifying that the Neighbor Duct effectively increases thrust. (Patent granted)
When installed on actual vessels, sea trial results confirmed energy-saving effects equivalent to those observed in the model tests.