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ENCIT 2020
18th Brazilian Congress of Thermal Sciences and Engineering
COMPUTATIONAL SIMULATION OF TRANSIENT FLOWS WITH CAVITATION
Submission Author:
Elias Dias , RJ , Brazil
Co-Authors:
Elias Dias, Helcio Orlande, Felipe Sant'Anna Nunes
Presenter: Elias Dias
doi://10.26678/ABCM.ENCIT2020.CIT20-0723
Abstract
In a transient flow, caused by water hammer, vaporous cavitation can occur when the pressure drops to the vapor pressure of the water. The cavitation process is dangerous and can damage pipelines; therefore, studying and understanding this phenomenon may give us important insights regarding its occurrence and behavior. Throughout the last decades, many studies have been developed in this area due its economic importance. In this work, it is performed the numerical simulation of a one-dimensional transient flow in a straight pipeline generated by a sudden valve closure located at the end of the pipeline. The goal is to predict the pressure peaks at the valve section. For the simulation, a model based on the conservation of mass, conservation of momentum and a transport equation is built. The dependent variables to be evaluated are density, velocity and vapor mass fraction. To compute the pressure, a constitutive relationship is needed. It is assumed that the bubbles are uniformly distributed along the pipeline and the mixture is homogeneous; therefore, liquid and gas have the same velocity. Two distinct numerical methods are used to solve the mentioned problem: the FORCE scheme and the MacCormack method. The results obtained are compared with numerical and experimental results available in literature. The results showed that the MacCormack method produces oscillations, which are expected in a second order, dispersive method. These oscillations are not seen in the FORCE scheme. Nonetheless, it was shown that both methods are accurate in predicting the pressure peaks at the valve section.
Keywords
Cavitation, Watter Hammer, FORCE SCHEME, MacCormack
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