基于相对速度单元坐标系的深海拖曳线列阵动力学建模及其形态稳定控制

The known position and straight shape of the array are key points in improving the exploration-resolution for the system of deep towed seismic array. By means of the depth gauge and gyroscope, the method of inversion improves the ability in calculating the position of the array, but the pulse-dislocation of the seismic wave still exists in the result. What’s more, the method of inversion only predicts the shape of the array, and does not suggest the method that keeps the array straight. The dynamic simulation is proposed here to predict the shape of the array and to find the method that keeps the array straight, so that the exploration-resolution can be improved in the data-inversion and the data-collection two aspects. Firstly，the dynamic model of the array is established using the lumped mass method, and the singularity of the model is solved by a relative-velocity-element-frame that is created with the help of the relative velocity of the array in water; the parameters of the model are determined in the physical experiment, and the accuracy of the model is verified by the experimental test; the past towing environment can be reappeared based on the information of the towed body and the current collected in the said towing activity; after that, the shape of the array is predicted. The relationship between the shape and the disturbances is studied with respect to classical towing environments. The drag is added to stabilize the shape of the array based on that relationship, and the drag is optimized based on the sampling results. This project can improve the exploration-resolution, and promote the development of the device for the high-resolution ocean exploration.

准确计算线列阵位置，稳定其平直形态是提高深海拖曳系统勘查精度的关键，目前反演法借助深度和姿态传感器虽可提高计算线列阵位置的能力，但横向位置未知和传感器累积误差仍使计算结果存在地震脉冲同相轴错位的现象，并且反演法只逆向推算线列阵形态，无法研究控制线列阵平直形态的方法。本项目拟借助运动仿真预报线列阵形态，优化保持线列阵平直形态的拖曳阻力，从数据处理、采集两方面提高勘查精度。首先，基于集中质量法建立线列阵模型，借助线列阵的相对水流速度构建相对速度单元坐标系，解决模型的数学奇异问题；其次通过物理试验获取建模参数、验证线列阵模型的准确性；然后基于拖体运动和海流信息再现深海拖曳环境，预报线列阵形态。最后研究形态与扰动因素的关系，揭示外加拖曳阻力的稳定作用，以典型拖曳工况的仿真结果为样本，采用粒子群算法优化拖曳阻力。研究成果有助于提高深海拖曳地震探测系统的勘查精度，推进高精度海洋探测装备的研发设计。

深海拖曳式地震探测系统是精准勘查天然气水合物等深海战略资源的装备，准确计算拖曳线列阵位置，保持线列阵阵形平直形态是提高勘查精度的关键。鉴于海面反演法使用的全海深平均声速存在不确定性，并且反演法无法解释异常线列阵阵形,无法研究控制线列阵平直形态的方法。因此，本项目基于相对速度单元坐标构建拖曳线列阵动力学模型，借助物理试验和CFD仿真揭示阻力伞的运动-负载关系，最终实现给定拖曳工况的线列阵位置预报。海试结果表明仿真定位结果比传统反演法更合理，帮助反演法修正了全海深平均声速，解决了海面反演法声速不确定问题。其次，仿真设计研究揭示了拖体垂向沉浮扰动沿线列阵逐渐衰减的机制，给出了线列阵内嵌水听器的布放位置建议。第三，指出线列阵呈现“W”形态是由于线阵列缆头重力大于浮力的原因造成，并借助CFD仿真设计了平衡缆头多余重力的浮力块，同时借助线列阵动力学仿真提前证明了加装浮力块和阻力伞的线列阵阵形更平直光滑，该成果也在随后的海试中得到验证。第四，研究了2400多组线列阵尾部稳定装置---锥形阻力伞的运动-负载关系，并采用人工神经网络算法获得了阻力伞的代理模型，为阻力伞的尺寸选型设计奠定了基础。以上研究成果从数据处理、采集两方面提高了深海拖曳地震探测系统的勘查精度，推进高精度海洋探测装备的研发，全面实现了本项目的三个研究目标。此外，本项目还进一步研究拖体的运动-负载关系，采用多目标优化梳理了拖曳速度、拖曳缆长度、拖体俯仰角和拖曳深度之间的关系，为深海拖曳式地震探测系统的海上作业提供指导。