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<p>Plasma-based control of hypersonic boundary layer transition has garnered considerable attention, yet its underlying mechanisms remain poorly understood. This study investigates the effects of plasma generated by surface arc discharge (SAD) actuators on a Mach 6 flat plate boundary layer, focusing on the evolution of instability modes. The SAD actuators are modeled as localized cylindrical heat sources, and their effects are analyzed using direct numerical simulation (DNS) and linear stability theory (LST). The results demonstrate that plasma-induced disturbances significantly modify the mean flow, altering the characteristics of instability modes. DNS confirms that small disturbances evolve linearly within plasma-modified flows. Notably, the second mode is suppressed, while the first mode is significantly amplified, consistent with LST predictions. This amplification of low-frequency disturbances may explain the experimentally observed promotion of transition by plasma, as these disturbances are known to dominate the transitional stage. Furthermore, while excitation frequency examined in this study has minimal impact on the amplitude evolution of instability modes, increased plasma energy substantially enhances disturbance energy, potentially accelerating the onset of transition.</p>

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Mechanisms of plasma actuation on hypersonic boundary-layer instability and mode evolution

  • 期刊论文

  • 发表日期：

    2026年7月21日

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  • Zhehao Li,
  • Caihong Su,
  • Hesen Yang,
  • Hua Liang

摘要

Plasma-based control of hypersonic boundary layer transition has garnered considerable attention, yet its underlying mechanisms remain poorly understood. This study investigates the effects of plasma generated by surface arc discharge (SAD) actuators on a Mach 6 flat plate boundary layer, focusing on the evolution of instability modes. The SAD actuators are modeled as localized cylindrical heat sources, and their effects are analyzed using direct numerical simulation (DNS) and linear stability theory (LST). The results demonstrate that plasma-induced disturbances significantly modify the mean flow, altering the characteristics of instability modes. DNS confirms that small disturbances evolve linearly within plasma-modified flows. Notably, the second mode is suppressed, while the first mode is significantly amplified, consistent with LST predictions. This amplification of low-frequency disturbances may explain the experimentally observed promotion of transition by plasma, as these disturbances are known to dominate the transitional stage. Furthermore, while excitation frequency examined in this study has minimal impact on the amplitude evolution of instability modes, increased plasma energy substantially enhances disturbance energy, potentially accelerating the onset of transition.