Shock wave-induced fluid interface instability is a common scientific issue in aerospace vehicles and inertial confinement nuclear fusion. Shock tubes are often employed to carry out basic aerodynamics research. However, the controllable generation of regularly-shape, high-energy utilization converging shock waves and strong shock waves are still challenging.

A study published in 2024 and conducted by research teams led by Prof. LUO Xisheng and Prof. SI Ting from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences established a theoretical method for designing smooth curved wall surfaces with variable cross-section shock tubes, and developed an integrated, high-intensity multifunctional shock tube device.

Based on the device and techniques, researchers developed a discontinuous perturbation interface generation technology, pioneering the experimental and mechanistic study of strong shock wave impact on single-mode fluid interface instability in shock tubes. The study was published in Journal of Fluid Mechanics.

This nearly ideal discontinuous interface generation method enabled an instant decomposition of the initial gases of different densities separated by a 2-μm-thick polyester film. The decomposition occurred in the high-temperature environment formed by the strong shock wave without generating fragments that interfered with the flow field.

For the basic small-amplitude light-heavy single-mode interface configuration, researchers clearly captured the entire process of shock and interface evolution through shock tube experiments of shock-induced fluid interface instability with a shock Mach number higher than 3.0. 

Through quantitatively analyzing the evolution of interface disturbances under the main control parameters, researchers revealed the influence of strong compressibility effects on the evolution of interface morphology and disturbance amplitude, clarified the mechanisms behind the effects of transverse wave effects and shock wave proximity effects on the nonlinear evolution of disturbances, and established a prediction model for interface amplitude growth that was applicable to strong compressible flows based on experimental results.

Researchers will continue to focus on issues such as fluid-solid coupling and competition at the interface in the future.