engleski

3D CFD Calculation of Injector Nozzle Model Flow for Standard and Alternative Fuels

In this work multi phase flow and erosion analysis were done via simulations in AVL’ s Workflow Manager with FIRE Solver CFD application, for standard diesel and two alternative biofuels, FAME and DME, inside different nozzle models and with various boundary conditions. Driving force for fluid flow is static pressure difference between inlet and outlet. Analysis criteria were: phase volume fraction distribution due to cavitation, mass flow rate, absolute velocity profile vs. nozzle model narrow channel height and erosion MDPR. Nozzle model consists of narrow channel with sharp (type I) or rounded (type Y) inlet section, with or without downstream placed target, so there was a total of four different model geometries. Simulation results showed that cavitation was present in almost all cases and that clear difference between three observed fuels can be seen. Mass flow in channel type I was lower than one in channel type Y. When comparing three observed fuels, it was noticed that DME fuel usually had highest velocity, but lowest mass flow rate. Contrary to DME, FAME fuel showed highest mass flow rate despite lowest velocity. When designing fuel nozzles, cavitation and cavitation erosion should always be considered. Nozzles in which less cavitation occured, achieved higher mass flow rates for same boundary conditions. When comparing simulation results and physical properties of observed fuels, it can be concluded that density is a leading term in determining mass flow rate. Also, erosion model predicts more intensive MDPR value near narrow channel exit.

CFD; cavitation; multiphase flow; diesel; alternative fuels

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