Problems in determining pressure losses in pipeline systems of plants for pulsed impregnation of timber, hydraulic transport of logs and cylindrical capsules are discussed. Theoretical dependences for determining the coefficients of hydraulic friction of axisymmetric annular channels and annular channels with maximum eccentricity formed by walls of various roughness have been obtained. A dependence to determine the average coefficient of equivalent wall roughness, required to calculate the coefficient of hydraulic friction, is proposed. The obtained dependences are confirmed by experiments on a hydrodynamic test bench. The results confirmed the suitability of the dependences for calculating the reduced coefficient of friction of axisymmetric annular channels. For an annular channel with maximum eccentricity, an experimental dependence of the correction factor for calculating the reduced coefficient of hydraulic friction has been obtained. The results are compared with those of other researchers.
Grigorev et al. (Sat,) studied this question.