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为了减小流体对固体壁面的阻力, 基于蚯蚓生物学特征, 对蚯蚓背孔射流特性进行分析, 建立仿蚯蚓背孔射流的仿生射流表面计算模型, 采用SST k-ω 湍流模型对仿生射流表面的减阻特性进行数值模拟, 同时对数值模拟结果进行实验验证, 并以此研究了仿蚯蚓背孔射流表面的减阻机理.结果表明, 在一定条件下, 仿蚯蚓背孔射流的仿生射流表面具有较好的减阻效果; 在同一射流方向角下, 随着射流速度的增加, 减阻率逐渐增大; 在同一射流速度下, 随着射流方向角的增加, 减阻率呈先减小后增大的变化趋势; 数值模拟与实验均在射流速度为1 m·s-1、射流方向角为-30°时达到最大, 分别为8.69%, 7.86%; 射流表面改变了原有光滑壁面的边界层结构, 对壁面边界层进行了有效的控制, 减小了壁面的剪应力, 降低了壁面边界层的速度.In order to reduce the drag reduction of the fluid on the solid wall, based on the biology characteristics of earthworm, the earthworm's back orifice jet characteristic is analyzed. The bionic jet surface is modeled by imitating the earthworm's back orifice jet, and the SST k-ω turbulent model is used for numerically simulating the drag reduction characteristics of bionic jet surface, simultaneously the result of the numerical simulation is verified experimentally. On this account, the drag reduction mechanism of bionic jet surface is studied based on the imitation of the earthworm's back orifice jet. The results show that under certain conditions, the drag reduction characteristics of bionic jet surface for imitating the earthworm's back orifice jet are very effective. At the same angle of jet direction, the drag reduction rate increases with the increase of jet velocity; at the same jet speed, the drag reduction rate presents a tendency to increase after the first decrease with increasing the angle of the jet direction. The maximum drag reduction rates obtained from numerical simulation and experimental measurement both on condition that jet velocity is 1 m·s-1 and the angle of jet direction angel is -30°, are 8.69% and 7.86%, respectively. Jet surface changes the original boundary layer structure in smooth wall, thereby effectively controlling the wall boundary layer, and reducing the wall shear stress and also the velocity of the wall boundary layer.
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Keywords:
- jet/
- drag reduction/
- numerical simulation/
- boundary layer
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