Pressure recovery of an air-water annular flow through a straight-walled diffuser

摘要

Experimental pressure recovery data through a straight-walled diffuser is presented for both airflow and air/water annular flow. Detailed measurements were performed at the diffuser throat: a) dry gas velocity profiles (Pitot-static tube), b) liquid hold-up (gamma densitometer), c) liquid film thickness (conductance probes) and d) liquid film velocity (modified Preston tube). Boundary layer detachment was observed in one corner for small liquid flow rates, and the diffuser flow pattern changed into the "two-dimensional stall regime" for higher liquid flow rates. The diffuser performance, described by the pressure recovery coefficient, became significantly reduced as water was injected into the airflow.