仿生机器人拍翼非定常水动力特性

Unsteady Hydrodynamic Characteristics of Bionic Robot Flapping

本文参照蝠鲼推进过程,以二维Clark Y翼型近似代表蝠鲼鳍的剖面形状,对拍翼的非定常水动力特性进行了模拟.采取动态混合网格对计算域进行离散,使用高效的Delaunay映射方法进行流场更新,避免了传统动网格方法易产生负体积的缺点.由计算流体力学(CFD)方法得到了不同上区比例(p)和最大俯仰角度下的升阻力结果,提炼了不同p值对平均升阻力的影响规律,并针对合适的p值,比较了不同最大俯仰角度对升阻力的影响.结果表明:平均推力关于p值对称,且标准的正弦拍动过程(p=0.5)能使蝠鲼运动产生最大的平均推力,瞬时最大推力在等效迎角为8.6°时取得;在p=0.5时,最大拍动角不易过大,取为5°可使平均推力与升力达到最优状态,对应拍动效率为65.1%.

In this study,the mandala propulsion process is combined,and the two-dimensional Clark Y airfoil approximation is used to represent the cross-sectional shape of the manta fin and its unsteady hydrodynamic characteristics are simulated. The dynamic hybrid mesh is used to discretize the computational domain. The efficient Delaunay mapping method is used to update the flow field,which avoids the disadvantage that the traditional dynamic mesh method easily generates negative volume. The results of the lift resistance at different upper zone ratios( p) and maximum pitch angles were obtained by the computational fluid dynamics method.The influence of different p values on the average lift resistance was refined,and the different maximum pitch angles were compared to obtain the appropriate p values. The effect on the lift resistance was analyzed. The results show that the average thrust is symmetric with respect to the p value. Moreover,the standard sinusoidal flapping process( p = 0.5) can produce the maximum average thrust of the movement of the manta fin. The instantaneous maximum thrust is obtained at the equivalent angle of attack of 8.6° . At 0.5 o’clock,the maximum flapping angle is small. Taking 5° makes the average thrust and lift force reach the optimal state,and the corresponding flapping efficiency is 65.1%.