水下拖曳系统临界运动特性快速确定方法

Rapid Determination Method of Critical Motion Conditions of Underwater Towing System

在进行水文要素的剖面测量时,拖体需要做起伏运动,预设轨迹的周期和振幅决定了测量精度和范围。为了实现拖曳系统的自主化控制,确定预设轨迹的可行性条件十分重要。文中基于尾翼摆动角与拖体攻角的线性化假设,通过反演拖曳系统的预设运动轨迹,建立了尾翼摆动控制的动力学模型,推导出尾翼摆动角的解析表达式。经典型算例验证,结果与试验数据具有一致性。进一步,采用建立的模型快速确定水下拖曳系统的临界运动特性,以及母船前行速度与拖体起伏运动的协调关系,研究表明可将斯特努哈尔数作为预设轨迹能否实现的必要限制条件之一,该无量纲数与母船速度、预设轨迹的振幅和周期相关,反映了运动的非定常性。在斯特努哈尔数小于0.22范围内,可以通过控制尾翼摆动的方式,自主化实现设定运行轨迹。

The towing body is the main part of a towing profiler. It can realize waveform track movement and measure real-time multi-parameters of the ocean. Therefore, the period and amplitude of the preset trajectory determine measurement accuracy and range. To realize autonomous control of the towing profiler, it is important to determine the feasibility conditions of the preset trajectory. Based on the assumption of linearization of the tail swing angle and towing body attack angle, a dynamic model with tail swing control was established in this study by inverting the preset motion trajectory of the towing system and deriving the analytical expression of the tail swing angle. The theoretical results were in good agreement with the experimental data. Furthermore, the established model was used to determine the critical motion characteristics of the underwater towing system as well as the coordination relationship between the forward speed of the mother ship and the undulating motion of the towing body. The study verified that the Strouhal number can be considered as a condition for the realization of the preset trajectory, which is related to the speed of the mother ship as well as the amplitude and period of the preset trajectory and reflects the unsteady nature of motion. When the Strouhal number was less than 0.22, the trajectory could be reproduced autonomously by controlling the tail swing.