A NUMERICAL STUDY ON CAVITATION IN DIESEL FUEL INJECTOR

In diesel engines, the internal flow characteristics in the fuel injection nozzles, such as the turbulence level and distribution, the cavitation pattern and the velocity profile affect significantly the air-fuel mixture in the spray and subsequently the combustion process. Since the possibility to observe experimentally and measure the flow inside real size diesel injectors is very limited, Computational Fluid Dynamics (CFD) calculations are generally used to obtain the relevant information. The present work is focused on the study of cavitation in real size automotive injectors by using a commercial CFD code. The first objective of the current work is to assess the ability of the cavitation model included in the CFD code ICEM CFD to predict cavitating flow conditions. For this, the model is validated for an injector-like study case defined in the literature, and for which experimental data is available in different operating conditions, pre-cavitation and after the pro-cavitation. Preliminary studies are performed to analyze the effects on the solution obtained for various numerical parameters of the cavitation model itself and of the solver ANSYS CFX, and to determine the adequate setup of the model. From this work concluded that overall the cavitation model is able to predict the onset and development of cavitation accurately. There is satisfactory agreement between the choked flow conditions and the corresponding numerical solution. This study serves as the basis for the physical and numerical understanding of the problem.