Spray dynamics simulations for pulsatile injection at different ambient pressure and temperature conditions

Abstract

A numerical study on the transient characteristics of a pulsatile, iso-octane spray issuing from a pressure-swirl atomizer is presented. The effects of system pressure and temperature, as well as the initial fuel temperature on spray dispersion and evaporation, are highlighted. The computations were carried out using ANSYS FLUENT-15.0, assuming the spray dispersion to be axisymmetric. Gas phase turbulence is simulated using the renormalized group k- ε model, while the discrete phase model is used for tracking fuel droplets. The linear instability sheet atomization model is adopted for the primary breakup of the liquid sheet, and the Taylor Analogy Breakup and Wave Breakup models are adopted for the secondary breakup, depending upon the operating conditions. The drag force on the droplet is evaluated, after incorporating the effects of evaporation and neighbouring droplets, along with droplet shape distortion. The significance of droplet collision on the evolution of droplet size distribution is examined. The local mean drop sizes and spray penetration length are in agreement with the experimental results of the literature. The predicted results indicate that the spray is narrower and penetrates less at higher ambient pressure. In this respect, the additional force on droplets due to local static pressure gradient is examined in detail. The effect of ambient conditions on the spray evaporation process is studied based on the spatio-temporal evolution of the equivalence ratio of the mixture of fuel vapour and air.

The effect of electromagnetic load fluctuation on the gas exchange stability of a free-piston hybrid power system

“…The breakup of oil droplets is described by wave model, and a constant C2 is proposed to adjust the breakup time. The Gosman and Ioannidis models were used to describe the dissipation of oil droplets 36,37…”

“…The breakup of oil droplets is described by wave model, and a constant C2 is proposed to adjust the breakup time. The Gosman and Ioannidis models were used to describe the dissipation of oil droplets 36,37 in turbulent vortices. In this paper, we use Walljet1 model to construct a piecewise function to describe the wall impingement phenomenon.…”

Dynamic Numerical Simulation of Curved Surface Coating Trajectory Based on STL Slicing Algorithm

“…Their study discovered variations in the thickness between the three points. Muddapur et al [10] conducted a simulation on the transient characteristics of pulsating isooctane spray in a pressure swirl atomizer. The simulation results indicate that as the ambient pressure increases, the spray layer becomes narrower, and the penetration decreases.…”