Unsteady simulation of AUVs approaching seafloor by self-propulsion using multi-block hybrid dynamic grid method
Unsteady simulation of AUVs approaching seafloor by self-propulsion using multi-block hybrid dynamic grid method
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DOI：
10.1016/j.jfluidstructs.2022.103728
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发表时间：
2022-09-22
影响因子：
3.6
通讯作者：
Hu, Weifeng
中科院分区：
文献类型：
--
作者：
Wu, Lihong;Li, Shuo;Hu, Weifeng
自主水下航行器（AUV）已广泛应用于海底附近的各种用途，包括管道、电缆和结构检查；底部检测和跟踪；和底部安装的对接系统。下蹲是在海底附近巡航时出现的一个关键问题，它影响AUV的机动性和安全性。因此，需要对AUV水动力性能进行高精度预测，以获得安全的自动引导控制器。在这项研究中，采用多块混合动态网格方法，结合六自由度（6DOF）、用户定义函数（UDF）和任意拉格朗日-欧拉（ALE）方法，通过基于物理的自航式AUV接近海底的非定常模拟来研究其水动力性能。该模拟用于探索 AUV 在海底附近垂直面作业时所经历的复杂非定常运动的原理。结果表明，当 AUV 速度高于临界速度（0.5 m/s，H/D = 1.832，其中 R-e = 5.49 x 10(5)）时，AUV 会出现速度损失，阻力、推力和吸力增加。速度损失是由于阻力增量大于推力增量造成的。配平力矩的大小和方向对由两个低压区域引起的 AUV 速度变化高度敏感。一个区域位于由船头涡引起的 AUV 船首颈处，另一区域位于由旋转螺旋桨引起的 AUV 尾颈处。通过流动分析阐明了AUV自推进过程中AUV与海底之间的非稳态相互作用。 (C) 2022 Elsevier Ltd. 保留所有权利。
Autonomous underwater vehicles (AUVs) have been widely applied in the vicinity of the seafloor for various purposes, including pipeline, cable, and structure inspection; bottom detection and following; and bottom-mounted docking systems. Squatting is a crucial problem that occurs when cruising in the vicinity of the seafloor, which affects the maneuverability and safety of an AUV. Therefore, it is necessary to have a high-accuracy prediction of the AUV hydrodynamic performance to obtain an automatic guidance controller for safety. In this study, the hydrodynamic performance was investigated by a physics-based unsteady simulation of a self-propelled AUV approaching seafloor using multi-block hybrid dynamic grid method, combined with six degrees of freedom (6DOF), user-defined functions (UDFs), and Arbitrary Lagrangian-Eulerian (ALE) approach. This simulation was used to explore the principle of the complex unsteady motions experienced by an AUV operating at the vertical plane in the vicinity of the seafloor. The results indicated that, for an AUV speed higher than the critical speed (0.5 m/s at H/D = 1.832, where R-e = 5.49 x 10(5)), the AUV experienced a speed loss and increased resistance, thrust, and suck force. The speed loss was due to the larger increment in resistance than that in thrust. The magnitude and direction of the trim moment were highly sensitive to variations in AUV speed, resulting from the two low-pressure regions. One region was at the AUV bow neck induced by the bow vortex and the other was at the AUV stern neck induced by the rotating propeller. The unsteady interaction between the AUV and seafloor during AUV self-propulsion was elucidated by flow analysis. (C) 2022 Elsevier Ltd. All rights reserved.