Comprehensive Hydrodynamics Optimization For Hull Form Via MDO

Offshore oil and gas exploration is a high technology intensive field, mainly concentrated in offshore oil and gas geophysical exploration techniques and drilling technology. High-performance deep sea seismic vessel is an important link in offshore oil & gas exploration, development and utilization industrial chain. It is ocean-going vessel with small scale (less than 100 meters), to be navigated in unrestricted navigation area and operated in rough sea, which puts forward a higher request of the operability, so does the speed requirement of freedom of navigation for the mobility and flexibility in different area. So essentially, it's a multidisciplinary optimization (MDO) problem with multiple objectives for the design of this type of vessel.The research of hydrodynamic performance for the vessel at present, mainly involves the study of Resistance, Seakeeping and Stability. Our study was based just on the advanced idea of MDO.With iSight platform, the integration of different sub-disciplines, such as the module for the mould transformation and generation and the CFD solver with high accuracy, is available.We take the performance of resistance and seakeep as the optimization objective, and establish a comprehensive hydrodynamics optimization platform, which can automatically vary the shape of a parent hull by the major design parameters and do evaluate by invoking corresponding CFD solver.To evaluate the performance indicators of a new design, we direct use simulation code to analysis numerically. Thanks to the analytical model automatic generation system, it makes the design process more accuracy and flexibility. We don't have to spend a lot of time to collect relevant empirical formulas and consider their applicability. We mainly focus attention on selecting optimization strategy. For instance, we can use the high accuracy analysis tools to establish the high quality metamodel of performance indicators for the major design parameters by limited analysis, replacing the costly simulation calculation and improving the efficiency of the optimization process.Different approximation model technology will be used in the optimize platform. We introduce the high-order response surface model (RSM) techniques to improve the efficiency of the design space exploration when we use the Shipflow for numerical calculation in the process of the resistance optimization presented in case 1 in the chapter 5; For the establishment of the seakeepingability analysis and prediction model in the chapter 3, a neural model(NN) is introduced and trained by the vast quantities of database calculated by the Wasim, a software based on 3-dimensional time-domain panel method. With its good adaptability and self-learning function, we can get a metamodel with high quality.Different from the traditional method of weighting by transforming the multiobjective optimization problem into single solving problems, multi-objective genetic algorithm is adopted in the optimization method, through the comprehensive consideration of resistance and seakeeping performance, which takes into account the stability and the bound variable, a Pareto optimal solution set to be obtained. We can achieve the final solution by the trade-off analysis based on the solution set. Such multi-objective optimization algorithm can obtain the optimal solutions efficiently in the feasible region, and can be widely used in the field of vessel design.The system to be used in a late-model streamer seismic vessel's hull form design and optimization, and optimize the case.