附加质量CFD计算方法研究

Numerical studies of added mass based on the CFD method

为了形成具体的数值计算流程、探讨计算结果的影响因素,并研究外形对流态及附加质量的影响,以通用CFD软件FLUENT为平台,运用其中的动态网格技术,以三维水下物体为对象,进行了基于RANS方程的全粘流的附加质量计算方法研究.共计算了2种外形,计算结果分别与基于细长体假设的切片理论估算结果进行了比较.结果表明:圆台加圆柱形式的回转体较之单纯圆台形式(具有相同的长度与头尾端面大小)拥有较小的阻力和较低的附加质量;不同的外形计算,对时间步长的要求也不同.

In order to provide a concrete computation method,to find the affecting factors of computed results,and to explore the effects of shape on flow patterns and consequently added masses,added masses of 3D underwater objects considering viscosity were computed by the dynamic mesh method.These computations were based on general CFD FLUENT code and were made possible by solving Reynolds averaged Navier-Stokes equations.Two shapes were computed,and results were compared with those predicted by the strip theory and slender body assumption.It was shown that the combination of the cutoff cone and cutoff cylinder has a lower resistance force and lower added mass than that of the pure cutoff cone,which has the same length and section of the ends.Different shapes have different requirements on the time step of computation.