LDA Measurement and 3-D Modeling of Air Motion in Swirl Chamber of Diesel Engines

Test investigations of air flow in the swirl chamber of a diesel engine were successfully conducted using Laser Doppler Anemometry (LDA). Air velocities at certain points in the swirl chamber were measured under motored condition for several engine speeds. The mean velocity and turbulence intensity was calculated using the ensemble average method. A general three-dimensional micro-computerized code was modified from KIVA II and developed to simulate the air motion in the swirl chamber. In the model, the turbulent flow of air is modeled using the modified k-ε turbulent model. The model was applied on to a bell type swirl chamber diesel engine and fairly good agreement was shown between the LDA measurement data and the simulation results. The air velocity profile in the vertical section, cross section and side sections are given. The obtained results clearly demonstrate the three-dimensional characteristics of air motion in the swirl chamber, including the change and development of vortices.