四种扑动方式对水下扑翼推进性能影响数值分析

为了对比四种最常见的扑动方式对水下扑翼推进性能的影响规律，研究其对流场的影响机理，分别建立二自由度水下刚性扑翼计算模型。基于Realizable k-ε湍流方程，利用有限体积法（FVM）求解非定常雷诺平均N-S（URANS）方程，结合动网格技术对不同扑动方式下的扑翼非定常水动力性能展开数值计算，并对流场结构进行分析，揭示其影响规律。计算结果表明:四种扑动方式对扑翼推进性能的影响明显，方式3能够产生最大的平均推力，且整体不产生阻力，方式1次之，方式2与方式4不产生平均推力；四种扑动方式产生的平均升力均为0左右，但是方式1升力峰值最大，方式3升力峰值最小。

NUMERICAL ANALYSIS OF INFLUENCE OF FOUR FLAPPING MODES ON PROPULSION PERFORMANCE OF UNDERWATER FLAPPING FOILS

Four 2-DOF computational models of rigid underwater flapping foil are established to compare the propulsion performance, and to study the influence mechanism on flow fields, respectively. Based on the Realizable k-ε turbulent model, the Unsteady Reynolds Average N-S (URANS) equations are solved by finite volume method (FVM), and the numerical simulations about unsteady hydrodynamic characteristics of four underwater flapping foil motion modes are performed through dynamic mesh technique, and the structure of flow fields and the influence on it are analyzed. Numerical results indicate that:the influence of four flapping modes on the propulsion performance of underwater flapping foil is extremely diverse. The mean thrust corresponding to mode 3 is the largest, and there exists no drag during the whole motion cycle; the mean thrust corresponding to mode 1 is less than the former, and the mean thrusts corresponding to mode 2 and 4 are negative; the mean lifts corresponding to the four modes are all nearly zero, the instantaneous lift peak of mode 1 are the largest, and mode 3 can generate the smallest instantaneous lift peak.