2025S-GS3-4 Investigation on the Analysis Procedure of the Results of Self-propulsion Tests and Fitting of the Obtained Self-propulsion Factors by Polynomial Functions

Abstract

In the previous paper 1)， the author tried to apply the method of linear-superposition of numerical functions to express the self-propulsion test results in calm water. By using numerical approximations of non-dimensional coefficients of the measured thrust， torque and revolution of propeller， he could get the better shape of self-propulsion factors than the ones by individual analysis.

In this paper， he tries to investigate how to express the obtained self-propulsion factors by suitable functions of Froude number. He checked the application of polynomial functions， more specifically 2-nd， 3-rd and 4-th order functions. From the values calculated from the fitted 2-nd， 3-rd and 4-th order functions of self-propulsion factors， he calculated back the values of thrust， torque and revolution of propeller， and then， the difference of them from the measured ones.

By the examinations of the values of the difference， the author concludes the 3-rd order function of Froude number is suitable to fit the variation of self-propulsion factors， in the case of the examined test data.