Kavitacijska erozija v vbrizgalnih komponentah z uporabo polidisperznega kavitacijskega modela : doktorska disertacija

slovenian

doktorska dela

2012

cavitation   erosion   erosion damage   injector equipment   injector flow   injectors

Univerza v Mariboru, Fakulteta za strojništvo

This disertation deals with numerical prediction of erosive effects due to cavitation. Such flows appear in many industrial applications and are of special interest within industries producing and using fuel injection components. Ability to predict such internal flows by means of Computational Fluid Dynamics (CFD) allows for efficient design of injectors and other fuel delivery components, such as pumps, common rails, throttles. Accurate modelingof cavitating flows is a prerequisite for the prediction of flow aggressiveness and finally its erosive effects. Driving force for the onset oferosion damage are bubble collapses during vapor condensation. Repetitive implosions on the same surface of the exposed material will eventually result in material damage. Prediction of vapor generation and accurate transport of the bubbles is therefore crucial. Polidispersed cavitation model of AVL FIRE was taken as the basis of the disertation work. Material based erosion model was modified to fit into the fluid dynamics framework and implemented into theCFD code. The model assumes that the material cannot withstand hydrodynamicloads above the yield strength and estimates the aggressiveness ofthe cavitating flow as function of bubble collapses per unit area and the size of the collapses on the surface. It allows for prediction of erosion effects, which has extreme value in the design process of injection components. Combination of material based erosion model with the multiphase two fluid model is unique and it represents the core of the disertation. Several results are presented to demonstrate model's capability to quantitatively and qualitatively predict probability for erosion existence. Finally, the effects of eroded injector surface on spray propagation are outlined, hinting that erosion inside an injector will affect the combustion process.

08.08.2023