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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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Shaping discharge chamber of hollow cone valve
Nehudek, Adam ; Haluza,, Miloslav (referee) ; Šulc, Jan (advisor)
The thesis is dealing with the design and position of the discharge chamber of hollow cone valve and is based on model research. The research response especially to the existing bottom outlets, where the position of valve is changed as opposed to the current position. The change of the valve position causes construction interventions minimization and also required financial resources are minimized. The other case is to interchange the old cone valve and the new one. This action is supporting the idea of valve spare parts unfication. In the research has been defined the automodeling area of outlet jet diversion from valve axis for different remoteness between water surface level and valve. The outflow jet diversion angle from valve axis has been measured in relation with relative valve opening. The coefficient of outflow has been specified in relation with relative valve opening. Furthermore, it has been searched for the position of discharge plane, where the discharging is done without backsplash. The last part of model tests was the discharge effect evaluation of most used chamber shapes. In the final chapter has been recomended the optimal shape and position of discharge chamber in dimensionless units, relative to the inlet diameter of the valve, all this based on results of model research. These results will enable reliable and efficient design of additional adjustments of discharge chamber shapes.
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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.
|
|
|
Shaping discharge chamber of hollow cone valve
Nehudek, Adam ; Haluza,, Miloslav (referee) ; Šulc, Jan (advisor)
The thesis is dealing with the design and position of the discharge chamber of hollow cone valve and is based on model research. The research response especially to the existing bottom outlets, where the position of valve is changed as opposed to the current position. The change of the valve position causes construction interventions minimization and also required financial resources are minimized. The other case is to interchange the old cone valve and the new one. This action is supporting the idea of valve spare parts unfication. In the research has been defined the automodeling area of outlet jet diversion from valve axis for different remoteness between water surface level and valve. The outflow jet diversion angle from valve axis has been measured in relation with relative valve opening. The coefficient of outflow has been specified in relation with relative valve opening. Furthermore, it has been searched for the position of discharge plane, where the discharging is done without backsplash. The last part of model tests was the discharge effect evaluation of most used chamber shapes. In the final chapter has been recomended the optimal shape and position of discharge chamber in dimensionless units, relative to the inlet diameter of the valve, all this based on results of model research. These results will enable reliable and efficient design of additional adjustments of discharge chamber shapes.
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