Vízügyi Közlemények, 1967 (49. évfolyam)
4. füzet - Rövidebb közlemények és beszámolók
(4 3) the energy content in Section 1. With notations according to Eq. (42) the discharge may be expressed by the general expression given by Eq. (44), wherein k 1 = H 2/H 1 the coefficient representing energy loss, while Z depends on the geometry of Section 2, the so-called control section. Using the generalized expression and introducing the coefficient k 3 = h 1/H 1, the discharge through a rectangular cross section is given - in terms of the upstream depth - by the equation in Eq. (5), where the discharge coefficient is obtained from Eq. (52), while relative changes of the discharge coefficient are expressed by the equality of Eq. (55). Conveyance through triangular and trapezoidal (Figs. 4-5) measuring contractions is given by Eqs. (56) and (58), respectively. As to be seen, the latter may be combined from conveyances through a rectangular and a triangular section, in which both the ratio of critical depth and energy content charateristic for the trapezoidal section are, however, involved. Consequently if it is intended to use for critical discharge the formula Q=C..b Hf found in handbooks, it should be realized that the discharge coefficient of trapezoidal venturi flumes is necessarily variable and varies as a function of the measuring head (Figs. 6, 7). By the generalized basic equation opportunity is offered for taking into consideration the influence of velocity-, pressure- and energy loss distributions on the conveyance of structures. The manner in which the conventional discharge coefficient is influenced by the experimental coefficients characteristic for the phenomena mentioned, is readily determined and consequently, changes in the discharge coefficient caused by structural modifications of the structure may be predicted. The alterations by which conveyance through the structure can be increased and energy losses reduced are thus indicated by the equation. HYDRAULIC STUDY OF SPRINKLER LATERAL AND IRRIGATION HOSE Bogárdi, I. Dr. C. E., Miss Nagy, E. mathematician (For the Hungarian text see pp. 87) By the method described in the paper hydraulic parameters (pressure distribution, discharge) of lateral pipes used in sprinkler irrigation and hoses used in border irrigation can be determined. The difference equation (1) describing flow in pipes with concentrated outlets lias been transformed into a differential equation (2) by assuming continuous removal of water along the pipe. After experimental verification 1 this approximation has been checked by calculation, where solutions of Eqs. (1) and (2) have been compared. For the case of laterals and irrigation hoses most frequently encountered in practice Eq. (1) has been solved according to the block diagram shown in Fig. 2 using an electronic computer. The comparison revealed the approximation of continuous removal results in a very small error only and is thus permissible. The differential equation (2) can be solved in explicit form only for the case of g = 0, i.e., horizontal terrain. In hose irrigation terrain slope can be neglected — because of the low operational pressures - in rare instances only (Figs. 4 and 5). In this case the general solution of differential equation (2), obtained by development into Taylor series — Eq. (3) - must be recurred to. This solution becomes extremely simple for horizontal terrain —Eq. (4). Laterals and irrigation hoses can be dimensioned readily with the help of their rating curves, expressing discharge in terms of pressure at a representative point along the conduit. In the case of horizontal terrain this representative point is preferably the entrance to the pipeline, and then the rating curves can be calculated with the help of Eq. (3). Where allowance must be made for terrain slope, the general expression of rating curves - Eq. (6) — is written by derivating Eq. (3). In this latter case discharge may be expressed in terms of the pressure at the end (x = 0) of the
