Aeroacoustic signatures reveal fast transient dynamics of vapor-jet-driven cavity oscillations in metallic additive manufacturing

TL;DR

This paper demonstrates that aeroacoustic signals from vaporization in metal processing encode detailed, rapid transient dynamics of vapor-jet-driven cavity oscillations, enabling physics-based, real-time monitoring of vapor cavity evolution.

Contribution

It introduces a vapor-jet-cavity oscillation framework integrated with aeroacoustic modeling, linking sound to cavity dynamics in laser metal processing.

Findings

Airborne acoustics accurately track vapor cavity depth and oscillation frequency.

Cavity-jet-acoustic theory identifies a critical frequency for vaporization transition.

Aeroacoustic signals serve as scalable, physics-guided probes of rapid vapor-liquid dynamics.

Abstract

Aeroacoustic emissions from intense evaporation are widely measured yet often treated as noisy byproducts and used mainly in empirical monitoring. Here, we show that airborne sound encodes physics-governed sub-millisecond fingerprints of vapor-jet dynamics in excessive vaporization, exemplified by vapor keyholes in laser metal processing. From first principles, we develop a vapor-jet-cavity oscillation framework and incorporate it into an aeroacoustic formulation, thereby coupling measured sound to transient cavity depth and oscillation frequency. Reconciled with synchronized multimodal in-situ data, airborne acoustics enable accurate tracking of vapor-cavity properties within tens to hundreds of microseconds. Combined with newly discovered correlations, cavity-jet-acoustic theory recasts the transition from steady, pore-free to pore-shedding vaporizations as a critical-frequency event. Aeroacoustic emissions thus become scalable, physics-guided, and cost-efficient probes of rapidly evolving liquid-vapor systems.