Significance of Truckenbrodt's Energy and Momentum Coefficients for Loss Calculation in Ramified Pipe Systems

For one‐dimensional simulation of flow in ramified pipe systems loss prediction in junctions is essential. In the standard literature (e.g. [1]) total pressure loss coefficients serve this purpose. Elementary formulas follow from the principle of momentum and some simple assumptions [2]. They yield rather crude estimates, often twice as large as experimental values. Modifications described by Idelchik [3] look nice, but after all turn out to be not more accurate. We explain deviations and propose improved loss formula based on Truckenbrodt's energy and momentum coefficients [4], thus paying regard to velocity distributions over pipe cross‐sections. We further discuss extraction of the coefficient's values from experiments. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)