engleski

Modelling of Hot Diesel Injection Process Using Eulerian Multiphase Method

Numerical simulations of spray formed by high pressure fuel injectors are usually modelled by Eulerian-Lagrangian method, where motion of the droplet parcels is tracked through the flow field using Lagrangian formulation. The computational effort for this method increases drastically with increasing parcel number, making it useful mainly for sufficiently diluted spray. This method is not applicable in the dense spray region where the volume fraction of the dispersed phase is high. As a result, another method, the Eulerian multiphase, was applied in this work. The Eulerian multiphase method provides stronger physical coupling of the gas and liquid phase in the near nozzle dense spray region. This modelling approach treats all phases, gas and liquids, as interpenetrating multi-fluids represented by their volume fractions. A separate set of complete conservation equations, with additional source terms accounting for droplet dynamics, is solved for each phase with the same discretization and similar numerical techniques. Several numerical simulations of high pressure diesel injections combined with different chamber pressures were calculated and compared with the results of the measurement data. The results show favourable agreement when compared with the measurements, and yield the correct trends for both liquid and vapour penetration under different operating condition.

CFD; Diesel spray; Eulerian multiphase method

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