Effect Of System Parameters On Spray Characteristics Under Common Rail System

Fuel atomization of the quality directly decides combustion characteristics. Theoptimization of fuel system parameters plays an important role in improvingcombustion and reducing the emissions. Therefore, this article simulates fuel flow andatomization process under common rail system to study the influence of systemparameters on fuel flow and spray characteristics.The injector fuel flow of the internal process was simulated in the paper using Firesoftware to get flow characteristics of nozzle such as the pressure, velocity, cavitationand mass flow rate distribution. The impact of different rail pressure and differentnozzle hole diameter on nozzle internal flow characteristics were analyzed. The resultsshow that the needle valve movement influence fuel flow characteristics in the nozzle.The pressure, flow rate and the cavitation distribution were uneven. Another, the higherrail pressure is, the greater flow velocity is at nozzle exit surfaces.The greater nozzlehole diameter is, the faster velocity variation rate is, and cavitation appears earlier, Thelength of cavitation is longer, cavitation intensity increases. The bigger radius ofrounded inlet is, the export flow velocity is bigger, and cavitation appears later,cavitation intensity decreases.The above computation results of fuel flow in nozzle was used as boundaryconditions for the following spray simulation to get spray pattern and Spray parameterssuch as spray penetration, Sauter diameter and so on. The system parameters such as railpressure, and back pressure, nozzle hole diameter, radius of rounded inlet on theinfluence of the spray characteristics were studied. The results show that the railpressure is higher, the spray penetration is greater and Sauter diameter is smaller. Railpressure increase from60Mpa to100Mpa, spray penetration has increased27%.Theambient pressure is higher, the spray penetration is greater and sauter diameter is smaller in initial spray and greater in middle-later period of spray. The ambient pressureincreases from1Mpa to3Mpa, spray penetration reduced26mm. Nozzle hole diameteris smaller, spray penetration is smaller and sauter diameter with full development is toget the same value. Radius of rounded inlet is larger, the spray penetration is greater andsauter diameter is smaller. The spray penetration increases23mm and improves the12%,sauter diameter reduces16%from r/d=0.2to r/d=0.