零质量射流控制翼型跨声速激波抖振特性

Investigation on control characteristics of zero-net-mass-flux jet for transonic shock buffeting of airfoil

  • 摘要: 跨声速激波抖振严重影响飞行器的安全性能和操纵性能。针对激波抖振的控制问题,提出采用基于尾缘吹/吸气的零质量射流方法,以翼型NASA SC(2)-0714为研究对象,通过风洞实验获得激波抖振的基本特性,基于雷诺应力模型求解非定常雷诺平均Navier-Stokes方程开展数值模拟,研究了改变射流介入的时刻、攻角和自由来流的马赫数以及射流的强度对控制效果的影响。结果表明:零质量射流能够完全抑制翼型跨声速激波抖振,能否成功抑制以及控制效果的优劣与射流的介入时刻无关。射流在给定的多个翼型攻角和来流马赫数下都有效抑制了激波抖振,俯仰力矩系数的标准差基本下降了一个数量级以上,翼型升阻比平均提升超过10%,气动特性得到明显改善。射流强度对跨声速激波抖振的抑制作用存在临界值,当低于临界值时激波振荡减缓,当高于临界值时激波振荡完全被抑制。

     

    Abstract: Transonic shock buffeting poses a significant threat to aircraft safety and performance. This paper presents a novel approach utilizing a zero-net-mass-flux (ZNMF) jet method, implemented through trailing edge blowing/suction on the NASA SC(2)-0714 airfoil, to tackle the critical issue of transonic shock buffeting control. The fundamental characteristics of transonic shock buffeting were obtained through wind tunnel experiments. Numerical simulations, validated against experimental data, were carried out to investigate the control effects by the unsteady Reynolds-averaged Navier-Stokes equations based on the Reynolds stress model. Key parameters including jet intervention timing, angle of attack, free stream Mach number, and the jet strength, were analyzed to optimize the suppression of transonic shock buffeting. Results show that the ZNMF jet can completely suppress the airfoil transonic shock buffeting, independent of the specific jet intervention timing. This suppression is maintained across a range of angles of attack and free stream Mach numbers, yielding significant improvement in aerodynamic characteristics. Specifically, the standard deviation of the pitching moment coefficient is reduced by more than an order of magnitude, and the lift-drag ratio is increased by more than 10% on average. Furthermore, the study identifies a critical threshold for the jet strength in suppressing the transonic shock buffeting. Sub-critical jet strengths result in reduced shock wave oscillation, while application of jet strengths above this threshold completely suppresses shock wave oscillation, offering valuable insights for pratical implementation in aircraft design and operation.

     

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