Vízügyi Közlemények, 1961 (43. évfolyam)
4. füzet - IX. Képek a Föld különböző részeinek vízépítési munkáiról
(61 > c.) The method of A. P. Yufin The relationships are based partly ón theoretical considerations and the number of parameters involved is greater than in the formula of Roer. In the general case the critical velocity can be determined by Eq. (7), but in practice Eq. (8) can be used for homogeneous materials. For mixed soils the inhomogenity coefficient given by Eq. (9) should be substituted into Eq. (10) of the critical velocity. The computation results are plotted in Fig. 5. For determining the head loss Eq. (11) should be used in the general case, and Eq. (12) is suitable with homogeneous materials for practical purposes. With mixed materials the latter is modified to Eq. (12). The relationships of Nikuradse are used for clear water. The computation results are plotted in Fig. 7. d.) The method of A. Z. Evylevitsh The possibilities for transporting settled sewage sludge al sewage treatment plants have been considered, and the relationships obtained are given in a graphical form. These are suitable primarily for determining the figures of consumed energy, necessary for Lhe transportation of sewage sludge (see Figs. 8, 9 and 10). The conclusions arrived at are of a novel character and Lhe graphs corroborate the remarks made in connection wilh Fig. 1/a. The use of Lhe method is restricted to the transporlaLion of maLerials of light specific gravity, low concentration, fine gradation and rich in colloids. e.) The method of Tzarewsky : For determining the critical velocity Eq. (14) is given, while Eq. (14. a) serves for compufing Lhe friction loss. The latler involves Lhe use of Table XIII. The compufalion resulLs are plotted in Fig. 11. The advantages and drawbacks of lhe method are listed. f.) The method of Durand The design formulae given by Durand are based on large scale, extensive experiments which may be considered unique in the world. In these experimenLs lhe maLerials were classified according Lo parlicle size, and homogeneous, transitory, respectively heterogeneous mixes were established. For homogeneous mixes the crilical velocity was found to be in the vicinity of the boundary (limil) velociLy belween laminar and Lurbulcnt flow, while in the turbulent range the fricfion loss was found- lo be equal lo that of clear water. No detailed results are given for transitory mixes. For heterogeneous mixes — where a homogeneous mix develops nowhere in the flow — the criLical velociLy can be determined by Eq. (15), while the head losses are computed from. Eq. (16) and (20), respectively. Effects of changes in Lhe specific gravity of the solid, and in the grain size distribuLion were invesligated in detail. Newertheless, the formulae given apply Lo graded, i.e. homogeneous maLerial only. The compuLaLion resulls obtained by Lhe authors are plotted in Figs. 13 and 14. ResulLs of compulations relating to the material assumed are plotted, for comparing the meLhods described, in Figs. 15 and 16. The auLhors have found the method of Evylevitsh to be suitable for sewage sludge materials with high colloidal content, while those of Yufin and Durand for fine grained maLerials. In lhe case of coarse materials resembling river gravel the formula of Roer can be suggested for compuLaLion, whereas Lhe methods of Goryunow and Tzarewsky are suitable for rapid estimates. Translated by Z. Szilvássy Struct. Eng.
