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Influence of the wall roughness on discharge coefficient of orifice
Jinek, Josef ; Golík,, Pavel (referee) ; Zachoval, Zbyněk (advisor)
This thesis deals with the influence of the wall roughness on discharge coefficient of sharp-edged circular bottom orifice. It supposed to verify, summarize and extend knowledge of orifice discharge. Author of this thesis determine a discharge coefficient by measurement. Values of discharge coefficient were measured for roughness of the wall represented by different diameters of grains and these values were compared with available values published in specialized bibliography by different scientists. At the thesis end was made a summary evaluation.
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Hollow cone valve capacity in the restricted outflow conditions
Nehudek, Adam ; Haluza,, Miloslav (referee) ; Šulc, Jan (advisor)
The thesis aims to determine the influence partial or complete submerge of hollow cone valve by outflow on its capacity without space restrictions, by outflow into discharge chamber and by outflow into water tunnel of circular cross section. The valve capacity is for mutual comparability purposes usually characterized by discharge coefficient. Research works have been performed on a spatial hydraulic model of the valve with inlet diameter D = 67 mm and an apex angle of a cone 90°. Values of the discharge coefficient obtained from measurements were statistically analyzed. The dependence of discharge coefficient, expressed by energy head, on submerged level was approximated by an exponential function. Exponent value of this function express the dependance rate of valve capacity on downstream water level. This procedure didn’t demonstrate signifiant dependance downstream water level on hollow cone valve capacity, only on tests at outflow to water tunel showed a low increase in the discharge coefficient partly due to the influence of kinetic energy of the stream flowing out of the tunnel on the energy head and also due to underpressure. Independence of discharge coefficient value on valve head has been prooved for head greather than 232 mm. Also was defined 3 stages of interaction outflow jet from valve and downstream water, some of them may cause on real waterworks structures unfavorable situations (may affect excessive load on valve by pressure pulsations). The presented results allow better evaluation of bottom outlets capacity at higher water levels, when the valves are flooded. Significant effect of sufficient aeration (especially in long water tunnels) on valve capacity was also confirmed. Taking into account on the specifics of hollow jet valves and cone valves, it is possible to generalize some of this resultos on them as well.
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Influence of the wall roughness on discharge coefficient of orifice
Jinek, Josef ; Golík,, Pavel (referee) ; Zachoval, Zbyněk (advisor)
This thesis deals with the influence of the wall roughness on discharge coefficient of sharp-edged circular bottom orifice. It supposed to verify, summarize and extend knowledge of orifice discharge. Author of this thesis determine a discharge coefficient by measurement. Values of discharge coefficient were measured for roughness of the wall represented by different diameters of grains and these values were compared with available values published in specialized bibliography by different scientists. At the thesis end was made a summary evaluation.
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Hollow cone valve capacity in the restricted outflow conditions
Nehudek, Adam ; Haluza,, Miloslav (referee) ; Šulc, Jan (advisor)
The thesis aims to determine the influence partial or complete submerge of hollow cone valve by outflow on its capacity without space restrictions, by outflow into discharge chamber and by outflow into water tunnel of circular cross section. The valve capacity is for mutual comparability purposes usually characterized by discharge coefficient. Research works have been performed on a spatial hydraulic model of the valve with inlet diameter D = 67 mm and an apex angle of a cone 90°. Values of the discharge coefficient obtained from measurements were statistically analyzed. The dependence of discharge coefficient, expressed by energy head, on submerged level was approximated by an exponential function. Exponent value of this function express the dependance rate of valve capacity on downstream water level. This procedure didn’t demonstrate signifiant dependance downstream water level on hollow cone valve capacity, only on tests at outflow to water tunel showed a low increase in the discharge coefficient partly due to the influence of kinetic energy of the stream flowing out of the tunnel on the energy head and also due to underpressure. Independence of discharge coefficient value on valve head has been prooved for head greather than 232 mm. Also was defined 3 stages of interaction outflow jet from valve and downstream water, some of them may cause on real waterworks structures unfavorable situations (may affect excessive load on valve by pressure pulsations). The presented results allow better evaluation of bottom outlets capacity at higher water levels, when the valves are flooded. Significant effect of sufficient aeration (especially in long water tunnels) on valve capacity was also confirmed. Taking into account on the specifics of hollow jet valves and cone valves, it is possible to generalize some of this resultos on them as well.
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