Computational investigation of diesel nozzle internal flow during the complete injection event

Abstract

Currently, diesel engines are calibrated using more and more complex multiple injection strategies. Under these conditions, the characteristics of the flow exiting the fuel injector are strongly affected by the transient interaction between the needle, the sac volume and the orifices, which are not yet clear. In the current paper, a methodology combining a 1D injector model and 3D-CFD simulations is proposed. First, the characteristics of the nozzle flow have been experimentally assessed in transient conditions by means of injection rate and momentum flux measurements. Later, the 3D-CFD modeling approach has been validated at steady-state fixed lift conditions. Finally, a previously developed 1D injector model has been used to extract the needle lift profiles and transient pressure boundary conditions used for the full-transient 3D-CFD simulations, using Adaptative Mesh Refinement (AMR) strategies to be able to simulate the complete injection rate starting from 1 micrometer lift.

Impact of alternative and fossil diesel fuels on internal flow of injection nozzle

“…This indicates that the nozzle design was optimized for high speed and load engine operating modes. The values obtained are considerably lower than those published in Salvador et al 41,43 and He et al 57 surely because the engine load and, consequently, that the injection pressure values are not as low as in the present study.…”

“…Diesel fuel viscosity was obtained by means of correlations (equations (5) and (6)), both previously published in Salvador et al 41 In equation (6), the multiplying factor has been modified for obtaining the fuel viscosity at 40°C, whose value is presented in the Table 1. In the equation (5) the subscript fl has been replaced by d .…”

“…Fuel density has been modelled by means of the Tait equation (equation ( 4)), where the exponent n = 7 as suggested in Cristofaro et al 40 r 0 is fuel density as function of temperature at ambient pressure and K is the fuel compressibility module. The diesel fuel density at ambient pressure has been calculated through the expression r d, 0 = 1061:5 À 0:7471T, while the compressibility module was calculated by means of the expression K d = 3748:7 À 7:127T, both presented in Armas et al 5 Diesel fuel viscosity was obtained by means of correlations (equations ( 5) and ( 6)), both previously published in Salvador et al 41 In equation ( 6), the multiplying factor has been modified for obtaining the fuel viscosity at 40°C, whose value is presented in the Table 1. In the equation ( 5 In equations ( 4) and ( 5) p is the local pressure (in MPa).…”

“…36 However, the most of the consulted works model the turbulence by means of k − ε equations. 37–43 This is justified by the reasonable balance between the computational time cost and the precision of the calculation method.…”

Desirable effects of cutting grooves on inner side of small cooling tower on reduction in ground level pollutant concentration

“…The JIC is known as a challenging problem in fluid mechanics because of the created vortices in the flow field. Many authors [18,19] investigated the complicated interaction between the jet and crossflow to reveal the valuable information about the physics of flow. The flow and heat transfer characteristics in JIC problems is affected by the configuration of jet.…”