Prediction of Ship Effective Wake Field Using a Pure RANS-Based Methodology

摘要

Ship effective wake field is complex but very important for an optimum propeller design. Considering that ship effective wake field cannot be measured directly because of propeller induced velocity a pure RANS-based methodology was proposed for predicting ship effective wake field, and a detailed numerical procedure was given. First, RANS simulation of "hull with propeller" was conducted to predict the total velocity field, which is the resultant velocity field of the effective velocity field and the propeller induced velocity field. Second, the propeller was simulated alone using the nominal wake field as velocity inlet condition to predict the propeller induced velocity field. Here, the rotation rate of the propeller was adjusted to generate the same thrust as the propeller generates in the simulation of "hull with propeller" to guarantee the same propeller induced velocity field based on the wake assessment by thrust identity method. Free surface and hull boundary above the propeller were considered using a specially designed dummy stern. Third, by subtracting the propeller induced velocity field from the total velocity field, the effective wake field was obtained. Numerical results including the effective wake coefficient were validated by available experimental data.