Abstract
For the improvement of transient driving performance of diesel engine, it is effective to control the fuel injection timing and quantity using model-based control (MBC) on ECU (on-board) with cycle-by-cycle calculation. The authors previously developed an on-board in-cylinder gas flow model and wall heat transfer prediction model those are a part of models for MBC. This study measured in-cylinder gas flow velocity using the PIV measurement and the CFD analysis to obtain the turbulence intensity coefficients of in-cylinder gas flow expressed by the ratio between mainstream velocity and fluctuating vertical velocity towards in-cylinder wall. As a result, it was found that the turbulence intensity coefficients at intake and compression strokes obtained by the PIV measurement were 0.014 and 0.018, respectively, which were smaller than the coefficient of 0.041 from the CFD results. Compared with the heat flux measurements, the prediction errors of wall heat fluxes using the CFD’s and the PIV’s coefficients were evaluated to be 45.0% and 0.28%, respectively. These suggest the necessary to improve the determination of turbulence intensity coefficient.
