Study on Flow Characteristics in Right-Angled Pipe Fittings : 2nd Report, On Case of Slurries in Hold up Flow

Abstract

The authors made flow experiments on the three kinds of right-angled pipe fittings which had correctly geometrical shapes and were set in the horizontal plane. Their diameter ratios were 53.2/53.2, 53.2/42.1 and 53.2 mm/28.0 mm. Flyash and sand slurries were run through them in the "hold up flow" and in the various upstream velocities of the main flow and the flow conditions. Then the authors obtained the following conclusions : (1) The densities of slurries in the downstream of the main flow and the branch flow are equivalent. At the same concentration in weight the coefficients of the pressure loss in the main flow and the branch flow are equivalent in the case of flyash and sand slurries respectively. Both coefficients of the pressure loss in the main flow and the branch flow increase with the increasing concentration in weight, but the incremental rate of the former is less than that of the latter. (2) The pressure loss in the main flow is equivalent to that of a sudden enlargement and the pressure loss in the branch flow is the sum of a sudden contraction and a sudden enlargement as in the case of water flow. As the pressure loss in the branch flow, especially in slurry, is greatly influenced by the contraction, roundness at the branch corner may be very useful in order to reduce its pressure loss. (3) The experimental results were expressed as the empirical formulae including also the previous experimental results with the water flow.