一种基于低速、小振幅周期运动CFD数值模拟的水下滑翔机附加质量求解方法

Method for Solving Added Mass of Underwater Glider Based on CFD of Low-Speed and Small-Amplitude Periodic Motion

水下滑翔机在流体中变速运动会带动周围流体一起做变速运动,这一部分流体的质量称为水下滑翔机的附加质量.附加质量对水下滑翔机的动力学行为具有重要影响.本文提出了一种水下滑翔机附加质量求解方法,即利用计算流体动力学(computational fluid dynamics,CFD)方法对水下滑翔机在静止的无黏流体中低速、小振幅周期运动进行数值模拟,进而求得附加质量.使用商用CFD软件STAR-CCM+计算了海燕-L水下滑翔机的附加质量,与基于势流理论的H-S面元法计算结果相差5%以内;与水下滑翔机模型水池试验结果相比,除垂直于水下滑翔机机翼方向的附加质量λ_(22)以外,其他附加质量的相对误差在6%以内,优于常规的平面运动机构试验的CFD数值模拟等其他求解方法.该方法只需要建模一次,在同一个流体域中模拟水下滑翔机的4种运动方式,监控其所受水动力和力矩,即可得到水下滑翔机的附加质量,极大提高了附加质量求解效率.同时,该方法能适用于任意尺寸、形状的水下滑翔机,对不同型号水下滑翔机水动力外形设计、动力学建模都具有较大的参考价值.

The variable speed of the underwater glider in the fluid drives the surrounding fluid to undergo variable speed motion together with the underwater glider.The mass of this part of the fluid is called the added mass of the underwater glider.The added mass affects the dynamic behavior of the underwater glider.Using computational fluid dynamics(CFD),this paper proposes a method for determining the added mass of the underwater glider to numeri-cally simulate the low-speed and small-amplitude periodic motion of the underwater glider in a static inviscid fluid.The commercial CFD software STAR-CCM+is used to calculate the added mass of the Petrel-L underwater glider,which is within 5%of the calculation results according to the H-S method based on the potential flow theory.Com-pared with the underwater glider model pool test results,in addition to λ_(22) perpendicular to the wing direction of the underwater glider,the relative error of other added mass is within 6%,which is better than that in other solution methods,such as CFD numerical simulation of the vertical plane motion mechanism test.This method only needs to model once,simulates the four motion modes of the underwater glider in the same fluid domain,monitors the hy-drodynamic force and torque,and then obtains the added mass of the underwater glider,greatly improving the effi-ciency of the added mass solution.At the same time,this method can be applied to underwater gliders of any size and shape,with a great reference value for the hydrodynamic shape design and dynamic modeling of different types of underwater gliders.