Hidrológiai Közlöny 1993 (73. évfolyam)

5. szám - Papp Gábor: Törttengelyű energiatörő medencerendszer kismintavizsgálata

278 HIDROLÓGIAI KÖZLÖNY 1993. 73. ÉVF., 1. SZÁM Abstract: Keywords: PAPP GÁBOR Model tests on energy dissipating basins with non-aligned axes Papp, G. Model test on, and the arrangement of, a system of rectangular energy dissipating basins are described. The basins connect to a 7 m diasmeter tunnel and enclose an angle with each other in plan. The energy dissipating structure consists of a 7 m diameter tunnel, a 45 m wide upstream basin of rectangular cross section, the upstream weir, the similary 45 m wide downstream basin below the upstream weir, the downstream weir (sill) and the 35 m wide tailrace. The hydraulic model tests were performed at the laboratory of the Hydraulic Engineering Institute, Budapest University of Technology, on a 1:140 scale model. The aim of the first studies was to investigate in terms of the angular displacement of the two basin axes the relative horizonal position of the tunnel and upstream basin, the extent of verticai inclination of the upstream weir erest, further the necessary length of the upstream basin by which the supercritical jet arriving parallel to the upstream basin can be deflected mot effectively towards the direction of the tailrace, the velocity distribution can be made uniform at the entrance to the tailrace, while the mean velocity can be reduced to the level required to avoid scouring of the tailrace material. This was termed the layout study on the structure. The resulting generál layout is shown in Fig. 1. The angle enclosed by the axes of the upstream and downstream basins was varied and the cases of 0, 22,5, 45, 67,5 and 90 degrees were studied in altogether 50 alternatives. The experimentál variables and measurement points of the basins enclosing 90° are shown in Fig. 2., while the measurement data for the alternative found best in this layout, i. e., where the velocity distribution in the tailrace is most uniform and the mean velocity is lowest, are illustrated in Fig. 3. Such pairs of figures were plotted for each angular displacement, but only those for 90° were presented here. The optimál data of the generál structure layout have been plotted against the angle enclosed by the axes of the upstream and downstream basins in Fig 4. in a clear manner. The detailed studies on the various component units were performed for the 0 and 90 deg. cases, again at the model scale 1:140. The observation points in the 90°layout, the watersurface profilé and the hydraulic gradient at Q = 810 m /s discharge are shown in Fig 5. The local temporal meanvalues of flow velocity (direction and magnitude) measured in planes 1 and 2 metres above the bottom are shown in Fig. 7, while the corresponding values for the 0° layout are illustrated in Figs 6 and 8. In the upstream basin at the 90° layout the pressure- and valocity pulsations are shown in Fig 9 for the points 63 and 64, where the highest local temporal mean velocities were observed. The head and velocity distribution above the upstream weir at Q = 810 m/s discharge in the 90° and O'layouts are shown in Figs 10 and 11, respectively. In cross section 11 in the tailrace thewaterlevel, the velocity profiléin five verticals and the velocity distribution within the cross section are shown forthe90°and0° layouts in Figs 12. and 13, respectively. The totál head loss was found to be22.04m, theefficiency of energy dissipation 72 %, the average slope of the hydraulic gradient 0,179 m/m in the 90° layout, while the corresponding data for the 0° layout (aligned basins) were 21,39 m, 69,49 % and 0,158 m/m. The characteristicsof the hydraulic jump(depth and lenght) were studied inastraight basin atB = 45, 40.40,35,70 and 31,50 m widths and at the discharges 810, 700, 552, 400 and 297 m /s in each. The measurement data are presented. In Fig. 14 and Table 1. Relying on the measurement data and the experiences gained during the study the dimensions of the basins connecting to the 7 m diameter tunnel and of the tailrace were eventually determined and compiled in Table 2. Energy dissipating basins, hydraulic model stury, flood spillway, tailrace, hydraulics. Oki. mérnök, oki. alk. matematikus, műszaki egyetemi doktor. A Budapesti Műszaki Egyetem Vízépítési Tanszékének adjunktusa. Arcképét lapunk 1986. évfolyamának 3. számában, a 148. oldalon közöltük. 11! í ii H! f 11111 í! 6! i,f IIM B

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