Propeller Steady Performance Optimization based on Discrete Vortex Method

Abstract

The optimization procedure based on the variational method is formulated to get the optimum circulation distribution using the numerical lifting-surface theory. The discrete circulations are determined by solving the non-linear simultaneous equations obtained by variational formulations. The linearized numerical procedure, dealing with the non-linear terms through iteration, is found fast, efficient and robust. Comparative study with the well-known DTNSRDC Propeller 4119 shows that the new numerical code is reliable and produces a consistent result with the known optimum design. Sample design optimizations for three existing modern vessels were performed, and the propeller models were manufactured and tested for the open-water and self-propulsion performances in the towing tank. The gain in the quasi-propulsive efficiency for all the vessels tested is not significant but not negligible. The improvement in the efficiency is shown always possible and can be achieved by numerical procedures and verified by experiments.