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中文核心期刊

高速平板边界层微喷流阵列流动调控与降热减阻特性

FLOW CONTROL AND HEAT/DRAG REDUCTION CHARACTERISTICS OF A MICRO-BLOWING ARRAY IN HIGH-SPEED FLAT-PLATE BOUNDARY LAYER

  • 摘要: 微喷流技术作为高速飞行器流动调控技术的重要研究方向之一, 是一种可实现高效降热减阻的主动流动控制手段. 目前, 关于微喷流技术的研究主要集中在宏观尺度, 而气体微喷流在介观微孔尺度下的流动调控机理及其降热减阻机制仍缺乏系统性的研究. 本文建立了带有真实微孔阵列平板的计算模型, 通过数值模拟研究了微喷流阵列影响下Ma = 12 ~ 18高速层流边界层介观尺度的流动结构与表面气动力/热变化. 计算结果表明, 无喷流时微孔阵列结构不会引入额外气动力或热载荷, 而启动微喷流调控后, 近壁面流动结构发生显著变化, 热流与摩阻下降明显. 随着气体工质质量流量增大或相对分子量减小, 微喷流取得的降热减阻效果逐渐提升, 而微喷口的几何参数对微喷流气动力/热调控特性的影响甚微. 通过对比“多孔壁面 + 微喷流阵列”真实气动边界条件与“光滑壁面 + 均匀质量引射”传统等效气动边界条件的计算结果发现, 由于热扩散或组分扩散现象的存在, 传统等效气动边界条件仅适用于微喷流工质与来流气体一致时的气动力预测.

     

    Abstract: As one of the key research directions in flow control technology for high-speed vehicles, micro-blowing technology is an advanced active flow control method capable of effectively achieving heat and drag reduction, which is crucial for enhancing the performance and operational safety of high-speed aircraft. Currently, most existing studies on micro-blowing technology focus on the macroscale, mainly exploring the effects of large-scale parameters on overall flow fields. However, systematic research on the flow control mechanism of gas micro-blowing at the mesoscopic microhole scale and its intrinsic heat/drag reduction mechanism remains insufficient, restricting the in-depth application of this promising technology. In this paper, a high-fidelity computational model of a flat plate with a real microhole array is established. Prior to formal simulations, grid independence verification and numerical method validation are carefully performed to ensure the reliability and accuracy of calculation results. Through detailed numerical simulation, the mesoscopic flow structure evolution of the high-speed laminar boundary layer (Ma = 12 ~ 18) and variations in surface aerodynamic forces and thermal loads under the micro-blowing array are systematically investigated. Results show that in the non-blowing case, the micro-hole array causes no obvious interference to incoming flow nor introduces additional aerodynamic or thermal loads. When micro-blowing is activated, the near-wall flow structure is significantly reconstructed, leading to a notable decrease in both heat flux and friction drag. Parametric analysis indicates that the heat and drag reduction effects of micro-blowing improve gradually with increasing gas working medium mass flow rate or decreasing relative molecular weight, while the geometric parameters of micro-blowing nozzles have negligible impact on their aerodynamic/thermal control characteristics. A comparison between the "porous wall + micro-blowing array" real aerodynamic boundary condition and the "smooth wall + uniform mass injection" traditional equivalent one reveals that due to thermal or species diffusion effects, the traditional equivalent boundary condition is only applicable to aerodynamic force prediction when the micro-blowing working medium matches the incoming gas.

     

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