Simulation of Submarine Manoeuvring

Abstract: The best way to save money in a submarine design project is to, in an as early stage as possible, be able to find errors in a design or construction. A powerful method to find such errors is to put the design through rigorous testing in simulation software. This project has created a simulation program for a submarines cruising fully submerged. The software is using well-known and established equations of motion (EOM’s) that has been developed through the years. These equations describe the forces and moments acting on the submarine in six degrees of freedom and can be described with Newton’s second law of motion. The equations accelerations are integrated using the scipy.integrate.odeint module in Python to obtain the translational and rotational velocities for a time series. By integrating the EOM’s with different initial values and conditions a library of standard manoeuvring tests have been created together with graphically tailored representation for each test result. The software has been verified by comparing a few chosen test results with simulation software currently used by FOI. Through this comparison it is seen that the software correlates well with the current one in every aspect except one. There is an uncorrelated phenomenon when stern-plane diving is simulated. The error is identified to the stern-plane drag term in the surge equation, Xδsδs . Evidence shows that an error might exist in the current software and a dialogue with the manufacturer has been commenced. Until the error is solved, results from tests using stern-plane diving motions should be handled with care.