Abstract
The purpose of this study is to investigate a diesel combustion model that is capable of predicting the transient performance of a diesel engine and to apply it to new engine development including the development of transient controls. The latest diesel engine systems have become very complex, greatly complicating the calibration of engine controls. To solve these problems, a new diesel combustion simulator (UniDES) was developed to evaluate diesel engine systems, especially transient performance. To obtain high calculation speed and high accuracy, UniDES uses a multi-zone model and a probability density function (PDF). The multi-zone model treats the sprays and combustion in a cylinder as different zones. In addition to the main injection, UniDES also treats the 1st pilot injection, 2nd pilot injection, after-injection, and post-injection as zones. The interaction between sprays is treated as interaction between zones. A PDF is used in these zones to calculate the inhomogeneity in the zones. After predicting engine performance in the NEDC test cycle with UniDES+GT-POWER® and Matlab/Simulink®, the engine speed, fuel quantity, intake manifold pressure, exhaust manifold temperature agreed closely with the experiment results. Finally, this simulator was applied to the transient mode from diffusive combustion to PCCI and a suitable control method was researched.
KEYWORDS – Diesel, Combustion, Simulation, Transient, Prediction