Modeling of pressure conduits with nonuniform flow: Fid-Bau Portal

Modeling of pressure conduits with nonuniform flow

Malakhanov, V. V. / Gassan, Ebrakhim

Conclusions 1. The presence of local resistances on the path of pressure conduits and outlets leads to nonuniform flow of the water due to additional turbulence of the flow and, as a consequence of this, to a shift of the boundary of the similarity zone toward the zone of smaller Reynolds numbers, which makes possible a well-founded reduction of the scales of models according to formula (1). In this case a determination of the boundary Reynolds number Reb with the use of the equivalent roughness method can be carried out by Nikuradze's, Al'tshul's, or Prudovskii's formulas with substitution of the values of the relative equivalent roughness in them. However, before obtaining broader experimental data on determining the effect of various local resistances on Reb in nonuniform pressure flows, it is necessary to use formula (7) as the one giving more cautious results. 2. As shown by the calculations for determining the scales of models of sag pipes constructed in our country, disregard of the effect of local resistances in the form of bends, joints, grooves, i.e., determination of the boundary Reynolds numbers for flows in sag pipes as for uniform flows (Nikuradze's, Levi's, Al'tshul's, and Prudovskii's formulas) results in that the models of the sag pipes cannot be made in scales smaller than 1∶2–1∶5. Determination of Reb by formulas (6) and (7) with consideration of the effect of local resistances by the equivalent roughness method enables a well-founded reduction of the scales of the models to 1∶20–1∶50.