VISUALIZATION AND MEASUREMENTS OF VOID FRACTION IN A GAS-MOLTEN TIN MULTIPHASE SYSTEM BY X-RAY-ABSORPTION

A technique has been developed to measure void fraction using X-rays i n a 10 cm thick pool of molten tin with gas injection at various flow rates. Visualization of the multiphase mixture using high energy X-ray s can be performed at imaging rates of 220 fps with 256 X 256 pixel re solution or at 30 fps with 480 X 1128 pixel resolution. The images are subsequently processed to obtain two dimensional distributions of the chordal average void fraction in the mixture. The estimated relative uncertainty of the measurement is discussed in detail and shown to be of the order of 10% of the reported value.