Fuel Impingement in a Direct Injection Diesel Engine

Abstract

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Modelling Spray/Wall Interaction in Swirling Flows for DI Diesel Engines

“…Figure 8 compares calculated impinged spray penetration (indicated by lines) with the experimental data (indicated by symbols) generated by high-speed pho tography in the constant-volume bomb under simulated diesel engine conditions (air density) (28) for three differ ent fuel rail pressures (4.7, 6.1 and 7.8 MPa). The predic tions compare well except for some overprediction after 0.6 ms, which may be due to the fact that experimental data were obtained from high-speed movies of the backlit spray pattern and the start of injection could not be determined exactly because of the limited frame rate of the camera (28). Figure 9 compares the computed volume of the impinging spray at three ambient densities of 6.15, 9.23 and 12.3 kg/m 3 (indicated by lines) with the experimen tal data of Katsura et al (35) (indicated by symbols).…”

“…-mJO -pJ Pl ) + (m v /m,Xl -pjp } ) (23) In the absence of evaporation (m v = 0), equation (23) reduces to the form of reference (7), that is The equations (28) to (31) contain the derivatives of four dependent variables, viz. concentration, velocity, wall jet thickness and jet direction; of these four derivatives, the value of the directional derivative is available directly from equation (31).…”

“…concentration, velocity, wall jet thickness and jet direction; of these four derivatives, the value of the directional derivative is available directly from equation (31). The other three derivatives can be evaluated by solving equations (28) to (30) algebraically. Thus, the model reduces to an initial value problem.…”

“…Moment of inertia of air depends on the shape of the bowl-inpiston and the bowl offset and thus influence the angular swirl near the top centre position of the piston. Therefore, the influence of bowl-in-piston geometry on mixing becomes important and needs to be investigated both experimentally (28) and analytically (12). The actual angular momentum of the air at the end of com pression will be less than the angular momentum at the closing of the inlet valve due to wall friction.…”

Center for Advanced Propulsion Systems

“…The performance of this model was also tested by Naber (1988b) under simulated diesel pressures and densities at ambient temperature in a bomb study. The study found that the spray rebound was under-estimated by the model.…”