Application of Quasi-Continuous Method to Open-Water Characteristics Predictions of Propellers with Energy Saving Ducts

The quasi-continous method (QCM) was applied to open-water thrust and torque predictions of ducted propellers with different positions of the propeller and duct. Two methods to calculate the resultant velocity were discussed. The QCM results are in good agreement with the experimental data of the propellers positioned inside a duct. The results of propellers in the downstream part of the duct show no significant dependence on the length of the straight trailing vortex of the duct. Comparison with the results calculated without any duct indicates no improvement of the open-water characteristics calculated by positioning the present duct in front of the present propeller.