Constrained Multi-objective Large Deformation Shape Optimization of Blended-Wing-Body Underwater Glider

There is a strong relationship of mutual influence between different performance indexes of Blended-Wing-Body Underwater Gliders (BWBUGs). For example, the shape with better hydrodynamic efficiency often limits the allowable internal volume, and further affects energy carrying capacity of BWBUGs. In this paper, two design objectives for BWBUGs are considered: lift-to-drag ratio (LDR) and internal volume, and the size and position of internal equipment are changeable. Due to the variable layout size and position, the interference between shape and internal layout is more likely to occur, which is a complex and harsh constraint. To solve this constrained multi-objective engineering problem, the surrogate-based TCOR-NSGA-II method is presented, where a new constraint-handling method (TCOR) is proposed to handle constraints more effectively. This novel constraint-handling technique combines with Non-dominated Sorting Genetic Algorithm (TCOR-NSGA-II) to tackle constrained multi-objective optimization problems. TCOR-NSGA-II has been tested on the MW test suites, and the experimental results show high effectiveness and strong robustness compared with several existing algorithms. Finally, the surrogate-based TCOR-NSGA-II is used for the shape optimization of BWBUG, and a set of non-dominant solutions are attained, which can provide a variety of glider shapes, including large LDR, large internal volume and trade-off individuals between the two indexes.