ANGULAR VOID FRACTION DISTRIBUTIONS IN RANDOMLY PACKED FIXED-BEDS OF UNIFORMLY SIZED SPHERES IN CYLINDRICAL CONTAINERS

The angular void fraction distribution in randomly packed fixed beds o f uniformly sized spheres in cylindrical containers is analyzed by a n ondestructive method where the center coordinates of specially prepare d spheres are experimentally obtained using X-ray radiography and the angular void fraction distribution is determined geometrically from th ese center coordinates. The geometrical solution for the local angular void fraction is determined by dividing the packed bed of uniform sph eres into a large number of identical wedge-shaped segments. The local angular void fraction in each wedge-shaped segment is expressed in te rms of the solid segments coming from each sphere. The angular void fr action distribution is obtained from the local angular void fractions and their angular positions in the cylindrical container. The angular void fraction distribution is presented for four different diameter as pect ratios, D/d, ranging from 2.02 to 7.99. The height aspect ratio, H/d, of each cylindrical container is approximately 7.84. The data sho w that there is a linear relationship between the mean angular void fr action and the mean overall void fraction. For diameter aspect ratios greater than 6.0 the two mean void fractions are essentially the same. An empirical correlation is presented which accurately predicts the m ean angular void fraction as a function of the mean overall void fract ion for packed beds with diameter aspect ratios ranging from 2.02 to 7 .99.