Numerical Simulation Analysis Of Flow Field And Structure Improvement Of Nozzle Based On Fluent

As the final execution part of an internal combustion engine’s injection system, the nozzle plays an important role in atomization quality; eventually it will affect the power, economy and emission characteristics. Therefore, it has become an irresistible trend to make further research and analysis of the influence factors. By using Fluent, which is a kind of traditional fluid analysis software, nozzle flow field is analyzed and simulated comprehensively, and some results have been obtained.Previous research showed that the three causes of the fuel oil atomization are the air turbulence, internal turbulent disturbance and orifice cavitation inside. Among them, cavitation in the orifice plays the most important role. Following this guidance of the thought, this paper multi-faceted simulates the cavitation using different injection parameters and structure parameters, which used Euler-Euler method and joined the two-phase flow model and cavitation model. Injection parameters include injection pressure, back pressure, different pressure differential and different cavitation number CN. The simulation about the geometrical parameters is to research the nozzle inside influence of different K coefficients. The simulation results show that the cavitation number CN has a decisive effect in the strength of the cavitation. The greater the cavitation number, the more obvious the cavitation. Of course, the number has a certain limit, capping over it will only have a little effect. So that factors increasing the cavitation number are conducive to the spray quality, such as increasing injection pressure, reducing back pressure, increasing the nozzle differential pressure between the import and export, and so on.Using Euler-Lagrange method, the simulation about spray is to study the nozzle jet. The results show that there is a very important relation between the quality of the spray and the inlet velocity of jet. The bigger inlet velocity, the bigger spray cone angle and penetration distance. Of course, inlet velocity also has a certain limit.Finally, the structure of equal diameter orifice nozzle is optimized and improved. The main purpose is to eliminate the influence of indoor vortex flow about the ride and flow. By comparing pressures, velocities, turbulent kinetic energies and wall shear stresses in four key positions, the improved nozzle have bigger outlet flow, less energy dissipation, better spray quality and longer service life than the original nozzle.In this paper, the nozzle simulation results accumulate some experience in the field of the conclusion about the flow field changes, which is caused by different injection parameters and structure parameters. At the same time, it provides certain guiding value on nozzle design and some other fields in which cavitation phenomenon appears.