Recent progress in the study of transition in the hypersonic boundary layer

Area of Science:

• Fluid mechanics
• Aerodynamics
• Hypersonic flow

Background:

• Turbulence is a fundamental aspect of fluid motion and a critical challenge in fluid mechanics.
• Hypersonic boundary-layer transition is a key research area with significant implications for aeronautics, astronautics, and navigation.
• Understanding transition is vital for advancing high-speed flight technologies.

Purpose of the Study:

• To review recent advancements in the study of hypersonic boundary-layer transition.
• To discuss essential research facilities and experimental techniques for hypersonic flow research.
• To highlight critical issues and recent contributions in the field.

Main Methods:

• Review of recent developments in hypersonic boundary-layer transition research.
• Introduction of the hypersonic quiet wind tunnel for near-space flight data acquisition.
• Description of near-wall measurement techniques: temperature-sensitive paint, near-wall particle image velocimetry, and Rayleigh-scattering visualization.

Main Results:

• The hypersonic quiet wind tunnel is essential for obtaining realistic flight data.
• Advanced near-wall measurement techniques enable detailed analysis of flow phenomena.
• Instability and nonlinear interactions of different modes are identified as crucial factors in transition.

Conclusions:

• Recent progress in studying hypersonic boundary-layer transition has been significant.
• The development of specialized facilities and techniques is crucial for future research.
• Further investigation into instability and nonlinear interactions is necessary to fully understand hypersonic flow.