Studies on the Hydraulic Loss in Pipe Bends : Results for 90°-Screw Type Elbows

A knowledge of hydraulic losses and secondary flows caused by elbows in a pipe line is of great importance in the field of hydraulic engineering. The results with a single 90°-elbow and two 90°-elbows were published in the previous report, but from these results only, the hydraulic loss and the flow pattern due to three elbows or more, located successively in a pipe line, cannot be predicted perfectly. By using various combinations of three 90°-elbows, the relationship between the hydraulic loss and the secondary flow is investigated. The loss and the flow pattern are strongly governed by the geometrical configuration of the pipe when the distance between the neighbouring elbows is small. A comparison of this with the previous results gives an approach to estimate the secondary flow and the hydraulic loss which are caused by four elbows or more.