Research Of Propulsion System Efficiency For Dynamic Positioning System

For dynamic positioning system the most important factor determining the positioning capability are behaviors of thruster in the water. In contrast with ordinary vessel's propulsion system, the propulsion system of DPS value thruster output at low speed rather than high speed. Focusing on research of thrust loss possibly generated by DPS propulsion, hydrodynamic performance of DP propulsion system was studied in this thesis. Based on numerical simulation method and model test, it has researched the interaction between thruster and thruster, thruster and current, thrust and wave, aiming for reducing thrust loss and improving efficiency. It is proved that thrust loss could reach to 80% due to thruster-thruster interaction, and 44% due to thruster-hull interaction. The main factors causing thruster-hull interaction include Coanda Effect, fiction loss, pontoon effect (semi-platform) and so on.Also this research could provide theory basis for designing propulsion of DPS. To those who have already installed DPS propulsion system, the effective way to improve efficiency of propulsion system is optimizing the thrust allocation algorithms. The main methods to reduce thrust loss are to arrange thrusters with reasonable and effective distance. Beside, setting forbidden vector boundary in the optimal thrust allocation logic could greatly improve thruster-thruster interaction characteristics as well.This thesis provides a valuable reference for the practical engineering design of DPS, and an important analytical tool for thruster hydrodynamic interaction study.