Estimation of void fraction, bubble velocity and bubble size in two-phase flow with x-ray backscatter

A method, based on Compton back-scattering of X-ray is developed to estimate the size and velocity of bubbles in two-phase flow. The method utilizes time-depending signals to examine the behaviors of dynamic systems, such as two-phase flow. Three-dimensional density and its variation with time is measured with only one stationary X-ray tube and two sets of turnable detectors. The depth information are obtained directly from the measurement and there is almost no geometrical restriction for the object being tested, since both the X-ray source and detectors are located on the same side. The determination of the local density depends on a new developed noise analysis technique and the estimation of fluid velocity as well as bubble size is based on cross- correlation method while the density fluctuation are detected. In this paper the experimental setup is described in detail. A collimated, fan-like beam from an X-ray tube lies on a plane parallel to the flow direction. Two scattering points along the stream line are detected by two collimated scintillation detectors. Another set of detectors is also used to get a higher signal-to-noise ratio