Prediction of the friction factor in laminar flow through three-phase pipe-type power transmission line

The relationship between the friction factor and the Reynolds number for laminar isothermal fully developed flow through several cable configurations of a three-phase pipe-type electrical power transmission line is predicted. The predictions agree well with data taken from scaled down and full scale model tests. The RMS error is 15.4%. The friction factor varies widely among the configurations and therefore, Since the cable configuration on a real transmission system is arbitrary, the higher friction factor values found for the open triangular cable configuration should be used for design purposes.