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)