Intense pulses and regime transitions of gas–solid triboelectric currents in high-speed flows

The physical characteristics of gas–solid triboelectric charging under high-speed flows remain poorly understood due to limited direct experimental evidence. In this study, in situ triboelectric current measurements were conducted on a metallic blunt body in a shock-wave wind tunnel. The current signals change from random-like fluctuations at Ma3 to intermittent high-amplitude events at Ma6, and further to amplitude-modulated, non-stationary behavior at Ma8. Statistical analysis and continuous wavelet transform were used to analyze the signal features. The triboelectric current is interpreted as a macroscopic response of stochastic micro-contact events, indicating a transition in the temporal characteristics of the current with increasing inflow velocity, and providing experimental support for mechanistic interpretation of high-speed gas–solid friction.