Cavitation dynamics and surface erosion in fuel injectors considering the composition of fuel mixtures

Abstract

Cavitation and cavitation-induced erosion depend on fuel properties and operating conditions. The majority of studies on cavitation consider simple thermodynamic Equations of State (EoS), which limit the analysis of thermal effects occurring at high pressures and temperatures prevailing during bubble collapse. This can affect simulation fidelity, particularly when comparing fuels of different thermodynamic properties. The goal of this work is to examine, with the use of real-fluid thermodynamic models, pressure peaks and thermal effects owing to cavitation collapse in the vicinity of solid boundaries. A structured table is used to reconstruct the thermodynamic properties of the working fluids examined based on the Helmholtz Energy Equation of State. The table is incorporated into an explicit, density-based solver in OpenFOAM, using a Mach-consistent numerical flux for subsonic up to supersonic flow conditions. Different test cases have been considered to demonstrate the capabilities of the implemented methodology including a simple validation of the solver against the Riemann problem, a single spherical bubble of dodecane case collapsing in an infinite medium, a single spherical bubble collapsing close to a wall and a cluster of spherical bubbles collapsing close to a rigid wall. The ultimate objective of the research framework is to simulate bubble-collapse behaviour at pressure and temperature conditions relevant to Dual Fuel Internal Combustion Engines using different fuels. Thus, the present work aims to provide insight on cavitation evolution and relevant influence on injector reliability to eventually produce design guidelines for environmentally friendlier powertrains.