双侧滑动纳秒脉冲等离子体激励特性及其控制非对称涡的机理研究

The development of high-maneuverability aircraft of next generation requires new technology for controlling asymmetric separated vortices at high angles of attack. Nanosecond pulsed plasma actuation is a burgeoning type of active flow control technology. Some preliminary investigations on the control of asymmetric vortices over slender bodies by nanosecond pulsed plasma actuation have been performed in the world, but there are still some problems worthy of further studies, for example, the stimulation strength is not strong enough, the region of influence is small, and the control mechanism is not yet clear. This project proposes a double-side sliding nanosecond pulsed dielectric barrier discharge actuator (abbreviated as DSNP-DBD below) which combines nanosecond pulsed plasma actuation with a negative DC component. A new flow control method has been developed to control the asymmetric vortices by large area of controllable disturbance induced by this newly developed plasma actuator. Aiming at the key scientific issue of DSNP-DBD and the coupling mechanism between the vortices induced by DSNP-DBD and the asymmetric separation vortices, the characteristics of DSNP-DBD under the static atmosphere and different flow conditions will be revealed through wind tunnel experiment, numerical simulation and theoretical analysis. The flow control ability of DSNP-DBD will be verified, and the regularity and rules in the influence of various plasma actuation parameters on flow control effect will be acquired. It is expected that the coupling mechanism between the shock waves induced by the DSNP-DBD, the boundary layer and asymmetric separation vortices on slender bodies will be revealed. The achievements of this project will lay a foundation for the development of plasma flow control techniques for the aerodynamic design optimization of the slender body aircraft.

新一代高机动飞行器的发展迫切需要探索新的细长体大攻角非对称涡控制技术。纳秒脉冲等离子体激励是等离子体流动控制研究领域的前沿热点，国际上对纳秒脉冲激励控制细长体非对称涡进行了初步探索，但还存在激励强度低、区域小以及流动控制机理不清晰的关键问题。本项目以等离子体激励及其作用方式创新为突破口，提出纳秒脉冲与直流偏压组合的双侧滑动纳秒脉冲等离子体激励新布局，以及等离子体激励诱导宽范围可控扰动控制细长体分离涡的新思路。针对双侧滑动纳秒脉冲等离子体激励及其与非对称涡耦合的关键科学问题，通过实验、数值模拟和理论分析，揭示静止大气和典型气压、速度环境的激励特性，验证新型激励提升非对称涡控制效果的能力，获得激励参数对流动控制效果的影响规律、主导流动控制效果的关键参数，揭示等离子体激励诱导的冲击波、旋涡与细长体边界层和非对称分离涡耦合的作用机制，研究可为基于等离子体流动控制的细长体飞行器气动优化设计奠定基础。

为了获得战术优势，世界各国在先进战斗机和战术导弹的研发过程中，往往要求飞行器具有较高的机动性和敏捷性。而提高飞行器的机动性和敏捷性主要依赖于大迎角飞行状态的改善。当细长体飞行器在大迎角状态下飞行时，即使侧滑角为零，仍会产生方向随机、强度不定的侧向力。研究表明：飞行器细长体前机身背风区的非对称涡是产生这些随机侧向力的直接原因。本项目以等离子体激励及其作用方式创新为突破口，提出脉冲放电与直流偏压组合的双侧滑动脉冲等离子体激励新布局，以及等离子体激励诱导宽范围可控扰动控制细长体分离涡的新思路。针对双侧滑动纳秒脉冲等离子体激励及其与非对称涡耦合的关键科学问题，通过实验、数值模拟和理论分析，验证新型激励提升非对称涡控制效果的能力，获得激励参数对流动控制效果的影响规律、主导流动控制效果的关键参数，揭示等离子体激励诱导旋涡与细长体边界层和非对称分离涡耦合的作用机制，研究可为基于等离子体流动控制的细长体飞行器气动优化设计奠定基础。研究结果表明：诱导涡形成、演变和相互作用的非定常过程发生在归一化时间t *≤0.1（20ms）范围内，如果测量时间大于20 ms，将无法观察启动涡的动态演化过程；扩展DBD可以产生较强的瞬时气动效果，而TED滑动放电更有能力在激励器表面上方的立体空间内产生较强的气动作用。通过控制激励器诱导涡的强度和结构，可以使合成射流的方向发生转向，而且归一化偏置电压和偏转角之间存在拟线性比例关系。风洞实验结果表明： 扩展DBD对非对称涡的控制效果更好，涡系的对流不稳定性是影响前体非对称涡现象产生的主要因素。虽然目前最新战斗机已开始采用矢量推力发动机提供额外的侧向控制力。但因为受限于成本造价和飞行载重等诸多原因，并非每架飞机都适合安装矢量推力发动机。本项研究对于大多数高机动飞行器都是适用的，对于扩大飞行器飞行包线，提升舵面控制能效，探索和设计新型气动布局具有重要的参考意义。