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

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.