大型深海AUV无动力螺旋下潜运动特性分析

为了合理地设计大型深海自主水下航行器（autonomous underwater vehicle, AUV），针对其无动力螺旋下潜时的静力配置问题展开研究，重点分析其无动力螺旋下潜运动特性。首先，基于拉格朗日方程推导了大型深海AUV的动力学模型，并利用CFD（computational fluid dynamics，计算流体动力学）软件对其直航试验、斜航试验、悬臂水池试验和平面运动机构试验进行数值模拟，通过最小二乘线性回归法拟合得到了相应的水动力系数；同时通过对比给定推力条件下AUV的直航速度验证了动力学模型的有效性。然后，基于所构建的动力学模型，利用MATLAB/Simulink和S函数建立了大型深海AUV的六自由度运动仿真模型，分析了其净负浮力、重心纵向位移和稳心高度与无动力螺旋下潜稳态参数之间的关系。最后，设计了1∶10的大型深海AUV缩比样机，通过水池试验验证了动力学仿真结果的正确性。结果表明：净负浮力作为大型深海AUV下潜时的主要动力来源，决定了AUV的下潜速度和偏航角速度；净负浮力和重心纵向位移与稳心高度的比值越大，AUV的垂向下潜速度越快，下潜至6 000 m深度的用时越短；由于该AUV的体量较大，其纵倾角主要由重心纵向位移与稳心高度的比值决定，压载质量对重心位置和转动惯量的影响几乎可以忽略。研究结果可为大型深海AUV无动力螺旋下潜时的静力配置提供参考。

Analysis of motion characteristics of large deep-sea AUV unpowered spiral diving

In order to reasonably design the large deep-sea autonomous underwater vehicle (AUV), the static configuration problem of its unpowered spiral dive was studied, and the motion characteristics of its unpowered spiral dive were analyzed. Firstly, the dynamic model of large deep-sea AUV was derived based on the Lagrange equation and its direct route test, oblique towing test, cantilever pool test and plane motion mechanism test were numerically simulated by the CFD (computational fluid dynamics) software, and the corresponding hydrodynamic coefficients were fitted by the least square linear regression method; at the same time, the validity of the dynamic model was verified through comparing the route speed of this AUV under the given thrust condition. Then, based on the constructed dynamic model, the six-degree-of-freedom motion simulation model of large deep-sea AUV was established by using the MATLAB/Simulink and S-function, and the relationship between the net negative buoyancy, longitudinal displacement of gravity center, metacentric height and the unpowered spiral diving steady-state parameters was analyzed. Finally, a 1∶10 scaled-down prototype of large deep-sea AUV was designed, and the correctness of dynamic simulation results was verified by the pool test. The results showed that net negative buoyancy was the main power source of large deep-sea AUV, which determined the diving speed and yaw angular speed of the AUV; the greater the net negative buoyancy and the ratio of longitudinal displacement of gravity center to metacentric height, the faster the vertical diving speed of the AUV and the shorter the time to dive to a depth of 6 000 m; due to the large volume of this AUV, its longitudinal inclination angle was mainly determined by the ratio of longitudinal displacement of gravity center to metacentric height, and the influence of ballast mass on the gravity center position and moment of inertia could be almost ignored. The research results can provide a reference for the static configuration of large deep-sea AUV during unpowered spiral diving.