OPTIMIZATION OF A ONE-SHOT GAMMA-DENSITOMETER FOR MEASURING AREA-AVERAGED VOID FRACTIONS OF GAS-LIQUID FLOWS IN NARROW PIPELINES

A novel theoretical method for optimization of a gamma densitometer wa s applied in measuring the area-averaged void fraction in gas-liquid f lows. This theory provides design criteria that are comprehensive, mec hanistic, quantitative and all are obtained from first principles. Als o, a computer simulation was developed to test the design criteria and the predictions were compared with experimental data in the literatur e. Extensive experimental validation of the optimization theory was pe rformed. Direct in situ measurement of void fraction using differentia l pressure, a double-sensor resistivity probe and lucite mock-ups were compared with the optimized gamma densitometer measurements. The resu lts demonstrated good agreement between the reference measurements and the gamma densitometer in each case. The measured void fractions for the concurrent vertical forced flow ranged from 0.02 to 0.8, and spann ed the bubbly, slug and churn turbulent flow regimes in a 25.4 mm tube . The mock-up studies used lucite tubes of 12.7 mm outer diameter as s ubstitutes for the flow field over void fractions ranging from 0.03 to 0.8.