射流表面射流角度与射流速度耦合减阻特性

Drag Reduction Characteristics on Jetting Surface with Jet Angle-Jet Velocity Coupling

针对射流的仿生非光滑表面的减阻问题,运用可拓学基本原理建立了射流角度与射流速度耦元、耦合的可拓模型.利用SSTk-ω湍流模型在对射流表面射流角度与射流速度耦合情况下的减阻特性进行了数值模拟,并以此研究了射流表面压差阻力和黏性阻力减小的原因和射流表面边界层的控制行为.结果表明:在射流的角度、速度耦合的情况下,射流表面的减阻性能较好;当耦合的射流角度为30°、射流速度为1.2m/s时,减阻率最大,为28.10%;角度、速度耦合下的射流表面有助于减小模型壁面的速度梯度,增加壁面黏性底层的厚度,继而降低了模型壁面的压差阻力和黏性阻力,并且表现出良好的减阻性能;耦合下的压差阻力在一定程度上可以作为一种附加的动力,对射流表面流体起到推动的作用.

An extension model for coupling elements and coupling ways of the jet angle and jet velocity was built to reduce the resistance of unsmoothed bionics surfaces from the basic extension theory. With the SST k-w turbulence model, the simulation on the drag reduction characteristics with the jet angle-jet velocity coupling was performed, and then the reasons for reducing the viscous resistance and pressure resistance of the jetting surface and the controlling behavior of jetting surface towards the boundary layer were explored. The results show that the drag reduction effect of the jetting surface is better when the jet angle and the jet velocity are coupled. The maximum drag reduction rate reaches 28. 10% when the jet angle is 30° coupled with the jet velocity of 1.2 m/s. With the jet angle-jet velocity coupling, the jetting surface can reduce the velocity gradient at the wall and increase the viscous sublayer thickness, thus reducing the pressure resistance and viscous resistance at the wall and then leading to the drag reduction. In addition, the pressure resistance with the coupling, as an additional power to a certain extent, has a propelling effect on the fluid of the jetting surface.