An experimental study of sheet to cloud cavitation

• Published in: Experimental thermal and fluid science Vol. 83; pp. 129 - 140
• Main Authors: Wu, Xiongjun, Maheux, Etienne, Chahine, Georges L.
• Format: Journal Article
• Language: English
• Published: Philadelphia Elsevier Inc 01.05.2017; Elsevier Science Ltd
• Subjects: Bubbles; Cavitation; Clouds; Collapse; Correlation analysis; Flow velocity; High speed photography; Holes; Inlet flow; Photography; Pressure; Shock wave; Two-phase flow; Vortex shedding; Two-phase flow; Cavitation; Shock wave
• ISSN: 0894-1777; 1879-2286
• DOI: 10.1016/j.expthermflusci.2017.01.004

•Oscillating sheet cavity flow regime changes with inlet flow velocity.•Sheet to cloud cavitation can reach a stable periodic state.•Shock speed is much faster than reentrant jet speed and exceed local sound speed.•Passage of shock front generates a clear shock-like pressure surge.•Large vortical bubble clouds also create high pressure fluctuations. A 2D convergent-divergent test section was built to study experimentally sheet cavitation followed by bubble cloud formation. Flow visualizations and pressure measurements enabled correlating high speed photography observations with the pressures on the cavitating surface. These indicate that the frequency of the recurring sheet cavity decreases with increased inlet flow velocity. As the inlet velocity increases, the flow structure changes from vortex shedding with entrapped thin cavities, to a sheet cavity with a reentrant jet producing bubble cloud shedding, to a shock dominant cavity collapse flow regime. The two-phase bubbly flow shock front moves upstream at a speed higher than the local sound speed, creating a pressure surge clearly measured as the shock front passes over a pressure gauge. The sheet cavity breakdown during collapse leaves behind vortical bubble clouds.