CFD

KCS Self-Propulsion With a Biomimetic Fluke

Client:

Topic:

CFD self-propulsion analysis of the KCS vessel using a biomimetic propulsion system

Summary:

DOLPROP INDUSTRIES AB is developing a fluke propulsion technology. This biomimetic alternative propulsion generates thrust by performing a sine-wave oscillating motion, known as thunniform swimming. This is a primary mode of locomotion for numerous swimmers such as dolphins, whales, and some of the fastest fish species such tunas or barracudas.

The project main goal was to answer if the fluke oscillating propulsor significantly affects the pitching dynamics of the hull, in order to support the commercial phase and further system development. To achieve the aforementioned the following tasks were performed:

Analysis of benchmark towed barehull KCS ship case. Verification and Validation against Gothenburg 2010 workshop results.
Study of the pitching and sinking dynamics of the KCS hull propelled with a simplified fluke oscillating propulsor, at self-propulsion conditions.
Comparison of the previous system with the KCS using a standard propeller.

The total resistance, trim and sinkage were calculated and compared with the Gothenburg results at model and full scale, followed by the self-propelled simulations at full scale without wall functions to approximate the boundary layer. Viscous layers were added to achieve an average of y+ = 1.

Test cases:

Towed KCS barehull – Model-scale
Towed KCS barehull -Full-scale
Self-propulsion of KCS with fluke – Open-water fluke
Self-propulsion of KCS with fluke – KCS with fluke
Self-propulsion of KCS with KP505 – Fixed condition
Self-propulsion of KCS with KP505 – Free condition

Results:

The results demonstrated that ReFRESCO is suitable to capture and provide accurate solutions for this hydrodynamic problem with differences against the experiments, and published results, of less than 5%. It was numerically proven that the fluke can provide the required thrust (at lower RPMs than a conventional propeller) to propel the KCS and that bow and stern vertical displacements are not significantly different in magnitude for the oscillatory propulsor.