Effect of Shear Produced by Pipe Fittings on the Drop Size Distributions in Turbulent Flow of Kerosene/Water Mixtures
Drop size distribution data for kerosene-water dispersion were obtained in 1."I.D. pipe at a range of velocities in turbulent flow for a straight horizontal pipe. U shaped pipe and an offset pipe fitting oriented horizontally and vertically (upward and downward) to the main flow. A Lightnin in line static mixer was used as a premixer and the drop size distribution was measured by a Malvern 2600 analyzer. By changing the number of internal elements from 4 to 18 the mixer produced a primary dispersion with the mean drop sizes in the range of 50-700 um for the flow rates of 20 to 84 l/minute. The Sauter mean diameter, d32, was found to decrease as the number of elements was increased until an equilibrium drop size was reached. This equilibrium drop size varied with the fluid velocity through the mixer. For a dispersion of ~0.5% kerosene in water, the correlation of drop site with energy dissipation rate, e, was found to give a reasonable agreement with Kolmogoroff’s theory with an exponent in the range of -0.47 to -0.56 for a horizontal pipe and -0.60 to -0.72 for U-shaped and offset pipe fittings. The Sauter mean diameter was also correlated against Weber number with an exponent in the range of -0.71 to -0.83 for all the linings used.