Vízügyi Közlemények, 1962 (44. évfolyam)

4. füzet - IX. Könyvismertetés

(58) BRIEF PUBLICATIONS 1. Dr. К. Ziegler, mech. eng.: Reducing losses at pumping stations by positiveaction back-flap closing organs. (For the Hungarian text see pp. . . .). In low-head, high-discharge pumping stations the automatic flap valves commonly installed may, in some instances, cause considerable losses. The suggested positive-action flap-valve, operated by oil pressure, consists essentially of a lowconsumption oil pump which is started and shut down together with the pumping station, or pump. The closing organ can be raised by the small oil pump up to horizontal position, where it is shut down by a terminal switch. Upon shut-down of the main pump a magnet releases a slide, the oil is drained from the servo-motor and the closing organ effects closure at a rate defined by adjustable throttling. According to the illustrative examples the device is economical in spite of the added cost involved. The capacity of existing pumping stations can be improved appreciably by reducing the manometric delivery head. 2. Sz. Schneider, mech. eng: Operating conditions oï flap-valves, or needle valves at pumping stations. (For the Hungarian text see pp. . . .) The role of flap valves, or needle valves installed at pumping stations is to prevent backflow after the shutting down of the pump. They operate under two basically different operating conditions: rapid, and slow closure. In the case of slow closure a pressure rise exceeding the operating pressure can be avoided, but a more involved design is required. Rapid-closing valves differ in whether flow ceases simultaneously with the shutting down of the pump, or is continued for a time. The time of closure is governed by the length and elasticity of the pipeline. The pressure increase (or pressure drop) depending on the type of closure should be allowed for in dimensioning the pipeline. 3. Á. Laczkó (Miss), civ. eng.: Hydraulic control measurement at the Tiszalök Weir. (For the Hungarian text see pp. . . .) Bed-surveys, flow- and velocity measurements have been performed at the Tiszalök Weir, built on the upper third of the Tisza River. For the bed-survey and Atlas-type echograph, while for determining the direction of flow a current meter of Ott-Muldedag-type, and one of Hungarian manufacture, Type MK, capable of measuring the vertical flow direction too, have been applied. Comparing the results of bed-surveys (shown in Fig. 3 and 4) the development of scours downstream of the station, and at the upstream end of the pier separating the weir and the power station, can be observed. The purpose of flow measurements was on the one hand to provide a check on the results of model investigations before the construction, and on the other, to detect the causes of scouring. On the basis of results obtained protective measures against scouring could be suggested. <4. 0. Haszpra, civ. eng.: Method lor the conversion oï relationships determined graphically (For the Hungarian text see pp. . . .) The direct determination of relationships between measured data is insufficient for many purposes, it being desired frequently in a form relating to another scale, or without dimensions, etc. The conversion of each of the data involves, however, considerable work, and several sources of errors. If instead of the function z

2 = / (z

x), correlating the original pairs of measurement data Zj and z

2, the function щ = F (и

г) relating the new variables = zja and u

2 = zjb is desired, the problem can be solved with relatively little calculation work. The original data are entered into a log-log chart and correlated there. A transparent log-log grid having the same scale is placed over this master plot in a manner that is should be displaced in x direction by log a, while in the у direction by log b. Hereafter the curve of the master plot (together with the measurement data, if necessary) can be copied, and this yields the curve of the desired function u

2 = F(uj) *