Hidrológiai Közlöny 1968 (48. évfolyam)
8. szám - Varrók Endre: A nyomásvonal alakulása töltésezett folyók mellett
Varrók E.: A nyomásvonal alakulása Hidrológiai Közlöny 1968. 8. sz. 347 M T/4 3T/4 Fig. 4. One full period of the pressure wave generated in one of the experiments T and h„ are variables 4. ábra. A kísérleteknél előállított nyomásingadozás egy periódusa T és h 0 változó characterizes the instantaneous state of the periodic phenomenon. In the following, both concepts will be extensivelv used. The setup permitted the setting of arbitrary values of H in the rangé from 0 to 300 mm. The rate of rise and fali could be regulated stepwise, in 12 steps. The cycle frequency of the periodie motion could be modified both through the gearshift and through the regulator of H. After the setting of the desired values and the starting of the drive, the apparatus automatically repeated the chosen waveform an arbitrary number of times. The movable overílow weir was recharged by a jet of known yield and the overflow was determined by volume measurements at equal intervals of time. The difference gave the amount of water seeping into or out of the basin. The other overflow + 2 weir of fixed height was also observed, but not all wave-forms investigated caused overflow at theend. The temperature of water was regularly observed in the two overflow weirs. The changes in atmospheric pressure were recorded by means of a barograph, because sudden changes of atmospheric pressure might entail a eompensation of pressure between the air bubbles trapped in the sand and outer air space through the pressure gauge tubes, which effect might completely distort the phenomenon to be investigated. With the apparatus just described, we have investigated the damping of 23 different types of periodie pressure fluctuation. We have recorded five values of the rangé H from 1,1 to 4,4 cm; the rangé of the period T amounted from 7,55 to 89,75 min., that of the cycle frequency co from 47,7 to 4,02 degree/min. By means of the automatic drive, each flood wave was repeated four times. Discussion of results The evaluation of the photos of the piesometer tubes gave data-pairs of pressure and time. Pressures were attributed positive or negative signs according as they were above or below a dátum level of pressure. The fourfold repetition of the wave gave rise to four similar pressure waves at each pressure gauge outiét: this made it possible to reduce by appropriate transformations t—0, t—T, t—2T and t—3T to a single wave the four waves recorded at a given outiét. Fig. 5. shows the recordings of one form of pressure wave: in order not to clutter up the diagram we have shown the plot only of every other outlets, with distinctive symbols. The continuous line is the waveform computed from (4). t, min Fig. 5. Recording of one set of experiments (4) is the diagram of the pressure wave as described'by Eq. (4). The various plots represent the pressure waves as recorded by various pressure gauges 5. ábra. Az egyik változat mérési eredményei. (x) a vízállásingadozás (4) egyenlettel adott alakja. A pontsorok az egyes mérőhelyek mérési adatait ábrázólják
