仿生射流表面优化设计与减阻机理分析

来源期刊:中南大学学报(自然科学版)2014年第5期

论文作者:赵刚 李芳 杜军伟

文章页码:1449 - 1457

关键词:射流表面;减阻;数值模拟;正交试验设计;边界层

Key words:jet surface; drag reduction; numerical simulation; orthogonal experimental design; boundary layer

摘    要:针对不同射流表面参数减阻问题,建立仿生射流表面模型,利用SST k-ω湍流模型对其进行数值模拟,所得结果与实验数据吻合良好。运用正交试验设计法对影响射流表面摩擦阻力的因素进行分析,得到各因素对减阻效果和节能效果的影响规律:形状因子对减阻率和节能率的影响最大,流速比其次,流速比与减阻率和节能率呈抛物线关系,形状因子与减阻率呈线性关系,且随着形状因子增大减阻率增大,最大减阻率为15.06%,最大节能率为13.57%。由于射流流体的阻碍作用,在射流孔背流面形成逆流区,逆流区近壁面形成的剪应力方向与来流方向相反,局部摩擦因数为负值,并且由于射流流体对主流场的推力作用,使得边界层黏性底层厚度增大,速度梯度减小,摩擦阻力减小。

Abstract: To solve the problem of the drag reduction on different jet surfaces, a bionic surface was built. The numerical simulation was completed by using the turbulence model of shear-stress transport SST k-ω. The result of the simulation is in conformity with the result of the experiment. The factors which affect the effect of the drag reduction on the jet surface were analyzed by using the orthogonal experimental .The results show that the effect of the shape factor on the drag reduction rate and the energy conservation rate is the best and the effect of the velocity ratio follows. The relationships between the velocity ratio and the drag reduction as well as the energy conservation are like a parabola. The relationship between the shape factor and the drag reduction rate is linear. The drag reduction rate increases with the increase of the shape factor, the drag reduction rate can reach the maximum of 15.06% and the energy conservation can reach the maximum of 13.57%. Because the fluid coming from the jet hole hinders the fluid on the surface, it will lead to a reverse flow region on the lee side of the jet hole. The direction of the shear stress near the wall of the reverse flow region is contrary to the direction of the fluid on the surface. The topical friction factor is negative. Because the fluid from the jet hole thrust the fluid on the surface, the thickness of the viscous sublayer of the boundary layer increases, the velocity gradient decreases, and the friction resistance decreases.

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