Author(s): Tulio C. Lourenco Xavier, Rafael S. Morassi, Jayme P. Ortiz
Linked Author(s): Jayme P. Ortiz
Keywords: Cavitation; CFD; Dispersive valves; Turbulence; Multiphase flow;
Abstract: Physical modeling for the study of cavitation in dispersive valves may not be economically feasible, taking a lot of time to perform tests and to provide reliable data from measurements to be applied in a prototype. As a consequence, the use of CFD technique is an alternative methodology for these studies, with the advantages of being more economically feasible and able to reduce the time required for analysis, although, normally, it is necessary the numerical modeling calibration. Morassi (2016) and Morassi and Ortiz (2016) studied the influence of the dissipating chamber dimensions of hydroelectric power plant in dispersing hollow jet valve flow and took as reference the data resulted from Falcon Dam physical model studies. In the present study, the behavior of the cavitation occurrence for different flowrates was assessed following both work. 3D numerical simulation – CFD were carried out in a multiphase unsteady flow in which PISO algorithm was used in order to solve the set of equations of Reynolds-averaged Navier-Stokes (RANS). The liquid volume fraction contour lines and velocity streamlines were obtained and the distribution of liquid volume fraction and pressure coefficient for different sample locations were analyzed during time evolution. It was verified that cavities with mixture of vapor and liquid were formed at needle tip and the generation of cavitating vortices. These regions are characterized by having the smallest pressure around the valve.