Numerical & labratoty studies about cavitation phenomena in a bottom outlet pipe of dames

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Department of Civil Engineering

Numerical & labratoty studies about cavitation phenomena in a bottom outlet pipe of dames

Abstract

It’s clearly that water resources are important for creature and human life. So, many activities are used to keeps advantage and remove disadvantage of water resources. Outlets are the set of instruments which is used to conduct dam reservoir to outlet point in downstream. So, because of the importance this part of dam, the outlet operation analysis like channel, gates and outlet are most important.  Because of the under pressure flow in upper part of outlet gates and also decrease the flow energy in formed by many reasons and low quantities are comprised with the gate opening and it’s against to water head on the outlet gates which is caused the use of relations. The results which are approached in theory ways make unique errors for determining various parameters which is relevance to outlets like gates in low pressure and conductivity capacity. In this paper, with the viewpoint is study the distribute pressure in various point of outlet channel, determining of gate conductivity capacity and calculated their coefficient, occurrence cavitation study, the comparison many forms for conductivity after serviceGates and after emergency gates  while the operation of two gates together, also determine major decrees coefficient  in channel  like friction decrease, the gates transform decrease are formed by using approached data from the physical model of lower outlet Narmashir dam.  Thus the gates and channel physical model which have been used in watershed management.  The amount of pressure head in various points and conductivity in gate in three levels maximum, minimum and normal in reservoir are measured and shown in tables and diagrams. Also, by using of  Flow3D software in this head, which is stimulated in three (100, 80 and 60) opening and comprised to each other in case of experimental and mathematical condition.  The application gate in form of coincide (index and cavitation) in crucial points like gates groove and between them in gate are located in normal limited and physically declined the caviation but in case of synchronic operation  in some opening the pressure are negative and probably occurred the cavitation.