Concept Exploration of a Surface Effect Patrol Combatant Using a Multiobjective Synthesis Model

This paper demonstrates a concept design methodology for naval SESs that is adapted from modern surface combatant optimization techniques. Similar to current methods, a synthesis model is constructed that uses a variety of discrete and continuous input values to calculate ship characteristics and performance data. The model outputs are generated using a combination of first-principles and exact 3D geometry along with parametrics aggregated from conventional monohulls and SES historical data. A specifically formulated multiobjective genetic algorithm is integrated with the model. The algorithm explores the highly nonlinear and non-convex SES objective space to identify non-dominated design variants. The synthesis model and the associated design space for a patrol boat with a novel SES hullform is detailed. Tradeoffs are evaluated in objective criteria of cost and performance in high-speed littoral operations that include surveillance, reconnaissance, and surface warfare.

The Sea Striker: Foilers are back in the game

This paper presents how the recent evolutions of naval missions, threats and operation theatres have led to the need for a new kind of surface players in the modern warfare. Then, an innovative surface combatant, the Sea Striker, is introduced and her various assets and advantages explained and detailed, along with her limitations. Finally, some example of computation of Measure of Performance in different scenario are exposed, followed by a brief analysis and contextualization in order to justify the relevance of using ships like the Sea Striker in various naval operations.

Numerical Simulation of Viscous Flows Around a Surface Combatant Model at Different Drift Angles Using Overset Grids

Viscous flows around ship hull is of great complexity, and when the ship is advancing with drift angles, the flow field can be more complicated. In this paper, the viscous flow field around an obliquely towed surface combatant DTMB 5512 is computed using the unsteady Reynolds-averaged Navier–Stokes (URANS) method. The numerical simulations are carried out by the in-house CFD solver naoe-FOAM-SJTU, which is developed on the open source platform OpenFOAM. To refine local grids and simulate dynamic ship motions, the overset grid approach is applied. Grid convergence study is first performed at straight-ahead towed condition with three sets of grid number and the results show monotonically convergence. Six different drift angles for the DTMB 5512 model at Froude number of 0.28 are simulated and the predicted hydrodynamic forces and flow field are presented. During the simulation, the ship hull is free to trim and sinkage at a free surface environment. As for straight-ahead towed condition, the total resistance coefficient and flow field, i.e., wave pattern and wake region, between this work and the experiment are compared. Both force coefficients and flow field show good agreement with the available experimental data. For oblique towed conditions, the lateral force, yaw moment and the derived hydrodynamic derivatives are also presented and compared with the experimental results. The variation of wave pattern and wake region at different drift angles are presented and analyzed. The results show that the current approach can be an effective tool to predict the viscous flows and hydrodynamic loads for oblique towed ships.