Numerical Evaluation of the Influence of the Outlet Nozzle Diameter of a Piezoelectric Gas Injector on Its Flow Properties

Abstract

The paper presents the results of flow analyses of a piezoelectric gas injector with pulse action. The conceptual solution, due to the use of a piezoelectric actuator, is characterized by shorter opening and closing times. This promotes the precision of fuel dosing. It also meets current trends in environmental protection. The innovation in the injector under study is the use of a beam actuator comprising three layers, two active and one passive. The electromechanical characteristics of the converter were determined based on the method in which the actuator is treated as a bent beam with a locally implemented piezoelectric segment. Based on such assumptions, the deformation shape of the actuator and, as a result, the opening degree of the injector valve were determined. Flow studies were carried out using Computational Fluid Dynamics (CFD) in the ANSYS Fluent environment. The RANS (Reynolds-averaged Navier-Stokes) approach and the k-omega SST turbulence model were adopted. The solution was sought based on the standard SIMPLE scheme and polyhedral mesh. It allowed the determination of the flow characteristics of the analysed injector, with variable valve lift and outlet nozzle diameter.