Abstract The net buoyancy, driving force of underwater gliders, decreases gradually when the gliders dive or climb in the seawater, which increases the energy consumption and reduces the gliding range. The neutrally buoyant hull is an effective measure to reduce this buoyancy loss of underwater gliders. In this paper, a multiple intersecting spheres (MIS) pressure hull is designed to provide neutral buoyancy. A mechanical model of the hull is established with the thin shell theory, based on which the optimization is carried out by combining the penalty function method (PFM) and multiple population genetic algorithm (MPGA). Thickness of the spherical shell, reinforcing rib, width of the reinforcing rib, and intersection angle of the spherical shell are optimized for minimizing the buoyancy factor which is defined as the ratio of pressure hull mass to the undeformed displacement. Additionally, the mechanical model is verified by the finite element analysis and the pressure test. The results show that the MIS pressure hull can increase the buoyancy compensation by 69.69% and increase battery capacity of the glider by 12.89% as compared with conventional cylindrical hull. This will improve the navigation range and duration of Petrel-L glider more obviously when its hotel load is lower.

中文翻译：

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水下滑翔机中性浮力船体优化设计

摘要 水下滑翔机在海水中下潜或爬升时，净浮力即驱动力逐渐减小，增加了能耗，缩小了滑翔距离。中性浮力的船体是减少水下滑翔机这种浮力损失的有效措施。在本文中，设计了一个多相交球体 (MIS) 耐压船体以提供中性浮力。采用薄壳理论建立船体力学模型，在此基础上结合惩罚函数法（PFM）和多种群遗传算法（MPGA）进行优化。球壳厚度、加强筋、加强筋宽度、优化球壳的相交角以最小化浮力因子，浮力因子定义为耐压船体质量与未变形位移的比值。此外，力学模型通过有限元分析和压力测试进行验证。结果表明，与常规圆柱体相比，MIS耐压船体可使浮力补偿增加69.69%，使滑翔机的电池容量增加12.89%。这将在酒店负载较低时更明显地提高Petrel-L滑翔机的导航范围和持续时间。69%，滑翔机电池容量比传统圆柱形船体增加12.89%。这将在酒店负载较低时更明显地提高Petrel-L滑翔机的导航范围和持续时间。69%，滑翔机电池容量比传统圆柱形船体增加12.89%。这将在酒店负载较低时更明显地提高Petrel-L滑翔机的导航范围和持续时间。