Exploration of Cavitation-Induced Erosion Metrics in Throttle Flow Simulations

Abstract

Although there have been extensive experimental and computational investigations in characterizing cavitation phenomenon in both diesel and gasoline direct injectors, much is still unknown about the mechanisms driving cavitation-induced erosion, and how this complicated fluid-structure interaction should be modeled. To explore current modeling capabilities, a numerical investigation was conducted within the CONVERGE modeling framework to assess proposed cavitation erosion metrics in the literature, and their link to the predicted cavitation cloud collapse mechanism. The multiphase flow within the Winklhofer Throttle "U" geometry was modeled using a compressible mixture model, where phase change was represented using the Homogeneous Relaxation Model (HRM) and the turbulent flow evolution was modeled using a dynamic structure approach for Large Eddy Simulations (LES). After comparing the model predictions against available experimental data, representative condensation events and potential cavitation erosion sites were identified. The cavitation cloud structures responsible for potential material damage were visualized through the evolution of the vorticity field. For the modeled throttle geometry, it was found that the horseshoe cloud implosion mechanism was predicted to occur and generate excessive impact loads at the throttle boundary.

Time-resolved 3D imaging of two-phase fluid flow inside a steel fuel injector using synchrotron X-ray tomography

“…Even in larger diesel injectors for heavy duty applications, the orifices diameters can be as small as 200 μm 1 . The variability in their geometric features such as inlet corner sharpness and orifice diameter have been shown to influence internal flow, causing two-phase phenomena such as cavitation or flow-separation near the nozzle walls [2][3][4][5][6][7][8][9][10][11] . The occurrence of cavitation, or vapor-filled cavities, can not only lead to erosion in injectors, but also have an impact on the downstream spray development.…”