Abstract
Abstract In order to improve the performance of engines fueled with diesel fuel or diesel-like e-fuels so as to realize greener transportation, the V-type and Y-type intersecting hole nozzles, in which each hole is formed by the coalescence of two or three subholes, have been designed. In this article, the multiphase flow inside and outside the nozzle was numerically investigated using a volume-of-fluid large eddy simulation (VOF-LES) method to clarify the effects of the nozzle structure on the cavitating flow and primary atomization characteristics. The calculation was carried out at an injection pressure of 150 MPa and a back pressure of 0.1 MPa. Numerical results showed that unlike the L-shape pressure distribution along a cylindrical hole, for intersecting type hole nozzles, the pressure showed a stepped shape drop along the holes due to the overall convergent hole structure, which restrained the inception of cavitation. Consequently, the global loss of the flow over an intersecting type hole nozzle was lower by 24–37% than those of a cylindrical hole nozzle. Additionally, the jets emerging from the intersecting hole nozzles showed 50% wider spreading angles and 27% smaller droplet sizes than those of the cylindrical hole nozzle. Furthermore, the jets emerging from a Y-type intersecting hole nozzle showed enhanced atomization, which was found to be due to the unstable air suction near the outlets of this type of nozzle hole.
Highlights
Nowadays, sustainable development has become a general consensus all over the world
Where ρl is the density of liquid fuel, ṁ f is the mass flow, Ṁ f is the momentum flux, and ΔPo is the difference of injection and discharge pressure over the nozzle. ueff and Aeff are the effective velocity and the effective area of a hole, respectively; which are calculated as follows: ueff
The multiphase flow inside and outside the nozzle was numerically simulated using a volume-of-fluid large eddy simulation (VOF-large-eddy simulation (LES)) method to clarify the effects of the nozzle structure on the cavitation flow and primary atomization characteristics for cylindrical, V-type, and Y-type intersecting hole nozzles at 150 MPa injection pressure and 0.1 MPa back pressure
Summary
Sustainable development has become a general consensus all over the world. In the transportation sector, many researchers are discussing the transition from internal combustion engine vehicles to electric vehicles for green transportation [1,2]. A number of studies have confirmed that increasing the injection pressure was an effective way to promote atomization and mixing of the fuel and air, improving performances of diesel engines [16,17,18]. The interchanging of the major axis and the minor axis can effectively enhance the air entrainment and improve the atomization quality of the fuel in the spray process [32,33,34] Another interesting method is the use of group holes for nozzles. Leng et al [37,38] performed experimental and numerical investigations on the internal flow structure and mixing dynamics of V-type and Y-type intersecting hole nozzles, and found many vortex structures and high turbulent kinetic energy at the outlet field, which can improve the fuel atomization. The characteristics of the jet breakup near the outer intersecting hole nozzles are quantitatively analyzed in terms of discharge coefficients, spreading angles, and the probability density function of the droplet diameters
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