Laboratory Study of Frictional Flows in Commercial Pipes

Colebrook-White formula and Hazen-Williams formula are widely used for estimating the friction factor of commercial pipes. On the other hand Yoo (1993, 1995) has developed mean friction factor method and mean zero velocity point method as new approaches. His approaches were verified using the data collected by Colebrook. Yoo and Won (1995) have found the clear trends of equivalent roughness height and probability related to the pipe diameter. The present study is again focused on the verification of Yoo's approaches by conducting laboratory experiments. Galvanized iron pipes were used for the laboratory experiments, and in order to simulate the flow in commercial pipe several rough joints were artificially made by welding steel plates inside the pipe. The equivalent roughness of nojoint smooth galvanized pipe was estimated to be 0.032 mm, and the probability of smooth wall area was found to be decreased by increasing the number of joints.