An overview of flow instability at supercritical pressure

The present work aims to comprehensively review fluid flow instability at supercritical pressure to help readers understand its mechanisms, current research status, existing challenges, and future research directions efficiently and concisely. The review covers various aspects, including instability under various scenarios and distinct characteristics for different supercritical fluids, the mechanisms and influence law of flow instability, experimental and simulation methods employed, and recent developments in flow instability research. The operating conditions and geometric parameters play a significant role in flow instability. Moreover, variations in flow instabilities can be observed in different supercritical fluids, owing to the different trends and magnitudes of thermophysical changes in the pseudocritical region. Time-domain analysis and frequency-domain approaches are commonly used methods for studying flow instabilities. Besides, present issues and worthy topics of attention are proposed for future studies of flow instabilities at supercritical pressures.