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The flow in engine turbocharger compressors and turbines is highly unsteady in nature, as it responds to the intake and exhaust manifolds of the internal combustion engine. The optimization of the turbocharger system is therefore a very difficult task, since the devices operate at off-design conditions for most of the engine cycle. Experimental studies allow for improving the understanding on the behavior of the engine components, in particular when tests are performed under real engine operating conditions; however, the experimental tests can be more efficient if they are combined with theoretical simulation tools, which help to select significant engine operating conditions. In this paper, experimental investigations were performed on a flexible component test rig (expressly suited to perform tests on automotive turbochargers) at ICE Laboratory of the University of Genoa (ICEG-DIMSET).

Current regulations stipulate acceptable levels of particulate emissions based on the mass collected on filters obtained by sampling in diluted exhaust. Although precise, this gives us only aggregated information. If in addition to the mass based measurements, detailed chemical analysis of the particulate matter (PM) is performed, additional subtle information about the combustion process can be revealed. This paper reports the results of detailed chemical analysis of trace metal in the PM emitted from a single cylinder heavy-duty diesel engine. The trace metal concentrations are used as an indicator of oil consumption. Two techniques were used to make the trace metal concentration measurements. PM was captured on filters and trace metals were quantified with an Inductively Coupled Plasma Mass Spectrometer (ICPMS), and also an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) was used to perform particle size and composition measurements in real time.

In the first part of this study, a one-dimensional code was used to compare predictions from six different two-equation turbulence models. It is shown that the application of the traditional k-ε models to the viscous-dominated region of the boundary layer can produce errors in both the calculated heat flux and surface friction. A low-Reynolds-number model does not appear to predict similar non-physical effects. A new one-dimensional model, which includes the effect of compression, has been formulated by multiparameter fit to the numerical solution of the energy equation. This model can be used in place of the law-of-the-wall to calculate the surface heat flux. The experiments were performed in a specially-instrumented engine, allowing optical access to the clearance volume. Measurements of heat flux, swirl velocities, and momentum boundary layer thickness were made for different engine speeds.