基于计算流体动力学的两栖车辆水动力特性数值计算

Numerical Calculation on Hydrodynamic Characteristics for the Amphibious Vehicle Based on Computational Fluid Dynamics

应用计算流体动力学(Computational fluid dynamics,CFD)理论,建立某型两栖车模型带自由表面粘性绕流场的数学模型,阐述求解的数值计算方法。采用RNG k?ε湍流模型、流体体积法(Volume of fluid,VOF)和压力隐式算子分割(Pressure implicit with splitting of operators,PISO)算法,运用FLUENT软件对车体绕流场进行三维瞬态数值计算,得到绕流场的速度与压力分布、阻力和兴波特性,并结合相关试验数据验证了数值方法的正确性,解决了以往由于忽略兴波特性导致数值计算结果随航速提高误差不断增大的问题。在此基础上,对该两栖车外形提出了优化方案,计算分析车体首、尾端切角及车轮不同收、放状态对绕流场的影响。计算结果表明,两栖车改进后的水动力性能有了较大改善,航速10km/h时,减阻效果可达原车总阻力的51.2%,为减阻提速的研究提供了一定的参考。

The mathematical model of the flow field of an amphibious vehicle is established with accounting flee surface effort and the solving algorithm is explained by using the computational fluid dynamics （CFD） theory. The three-dimensional numerical simulation of the free surface flow is carried out by using FLUENT software based on RNG κ-ε turbulence model, volume of fluid （VOF） method and pressure implicit with splitting of operators （PISO） method. The velocity, pressure, resistance and wave of the models are obtained, the computational results agree well with the experimental results. Then primary research is carried out on optimizing the geometrical characteristics of the amphibious vehicle model and analyzing the influence of its cut angle and the state of the wheel. The computational results show that the hydrodynamic characteristics of the modified model are better than those of the original model, which reduces resistance by 51.2% and provides an effective reference for the study on reducing resistance and raising speed.