Our customer is a large shipbuilder of naval vessels. They are engaged in design and development of medium sized ship. As part of the design improvement plan of the ship structure, the customer wishes to optimize the hull for reduction in drag. As per the requirements of the user, the RCS of the ship is to be reduced to acceptable levels. Contribution of hull and superstructure on the ship must be studied where the problem in hull is coupled with hydrodynamics. Constraints of space and ship stability during the design changes are given by the customer.
Multiple techniques were used for the simulation of hydrodynamics of the ship. Time Domain Boundary Element Method was used to predict the hydrodynamic characteristics like drag, trim and sinkage of sea vessel. Sea keeping simulations were done to estimate the dynamics of ship in motion. Simulations were done for even sea state five (rough sea). This was followed by RANS CFD simulations on the ship. Multiple simulations were carried out at different surge speeds to calculate Resistance. Design changes were mutually discussed and simulated. After the hull was redesigned, RCS calculations were done using PO-PTD-SBR method. The code also simulated the effect of waves on the RCS of the ship.
To simulate the customer vehicle validations were carried out for Wigley’s case. Excellent matching was found between the experiment and simulations. Simulations were done for Zig-Zag manoeuvre, turning circle, pull-out manoeuvre etc. Hull design was changed as per the obtained results. For each design change RCS was also estimated. Superstructure had large scattering and the same was also modified. Project culminated in 70percentage reduction in RCS after three design changes.