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This paper compares bulk impulse-torque and 2D planar PIV steady flow-field measurements created by an engine cylinder head and intake system model using a steady-flow bench and evaluates operational aspects of the steady-flow test system. The model included a full-sized intake manifold and cylinder head section from a Chrysler 2.4L PFI four-valve per cylinder engine mounted to an optical cylinder. Two test system operational aspects were evaluated: (1) upstream versus downstream engine location relative to the flowbench (operational modes corresponding to flow bench pulling or pushing through the system), (2) PIV seeding particulate choice. Several dry and oil fog particulates were assessed however, of the options tested, only laboratory grade glass and consumer grade talc allowed long enough operation for practical data acquisition. Tests were performed over lift-over-diameter (L/D) ratios spanning from 0.1 to 0.3.

This research examines the interdependence of the control strategies of a high-pressure exhaust gas recirculation (HP-EGR) and a variable geometry turbocharger (VGT) on a medium-duty diesel engine in transient load operation. The effect on fuel economy, particulate and NO production were investigated through multiple tests of synchronously controlled VGT and EGR positions. An optimal steady-state strategy of the above determinants was defined as a function of the VGT’s boost pressure and EGR percent mass. The optimal steady-state strategy was then used to investigate the interdependence of the VGT and HP-EGR in transient load acceptence events which occurred over a range of 2 to 10 seconds. The faster transients increased deviations of boost and EGR levels from steady-state calibration values which consequently led to corresponding fuel consumption and particulate matter emission increases.

Hybrid vehicle engines modified for high exhaust gas recirculation (EGR) are a good choice for high efficiency and low NOx emissions. Such operation can result in an HEV when a downsized engine is used at high load for a large fraction of its run time to recharge the battery or provide acceleration assist. However, high EGR will dilute the engine charge and may cause serious performance problems such as incomplete combustion, torque fluctuation, and engine misfire. An efficient way to overcome these drawbacks is to intensify tumble leading to increased turbulent intensity at the time of ignition. The enhancement of turbulent intensity will increase flame velocity and improve combustion quality, therefore increasing engine tolerance to higher EGR. It is accepted that the detailed experimental characterization of flow field near top dead center (TDC) in an engine environment is no longer practical and cost effective.