R. Palmaccio

Numerical Analysis of a Small Turbo-Charged Spark-Ignition Engine

The reduction of green-house gas emissions, that is the reduction of engine fuel consumption, is becoming a primary requirement for the automotive industry as well as meeting current and future emission legislations. Performing high torque values with small displacement engines, the so-called “downsizing”, permits, in general, to limit some typical engine losses (for instance: pumping and friction losses), increasing the overall engine efficiency. This means to improve vehicle fuel economy and, as a consequence, the CO2 emissions avoiding a performance decrease. In this paper, the behavior of a small displacement turbocharged spark-ignition engine prototype, for medium size passenger cars, has been analyzed. 3-D numerical simulations have been carried out in order to achieve a lot of information on engine performance and control parameters. Thus, at different engine operating points, intake and exhaust manifold pressure, volumetric efficiency, high pressure curves, the flow field of the fresh charge within the cylinder, the air to fuel ratio distribution, the residual gas fraction distribution and so long have been calculated. Since, as usual, the turbocharged version of the engine under study derives from an existing naturally aspirated engine, the purpose of this investigation is to obtain a detailed picture of the variations produced by turbo-charging on engine main parameters. The increase of knock risk due to higher cylinder pressures has been evaluated as well. Thanks to the three dimensional analysis, sound information have been obtained, so that suggestions for modifying some geometric engine parameters, according to the variations imposed by turbo-charging, have been proposed. Computations have been performed by means of the 3-D AVL Fire code. Initial and boundary conditions have been evaluated by means of 1-D, unsteady computations running separately from the 3-D code. The model utilized in this study has been validated by comparing the obtained results to the measured data provided by the research center of the engine manufacturer.Copyright

Electromagnetic Disruption Loads on ITER Blanket Modules

In this paper we compute the electromagnetic loads (forces, torques, Joule losses) on passive conductors of the international thermonuclear experimental reactor (ITER) fusion device, currently under construction, following a disruption event, i.e., the sudden loss of magnetic confinement. An original integral formulation is used, able to automatically deal with complex topologies like the ones to be studied. Non-isotropic homogenized resistivities are used to take into account fine geometrical details. A suitable inverse problem is solved in order to compute the forcing terms.

Electromagnetic transient studies in the ITER tokamak

The ITER tokamak is a very complex electromagnetic system that requires a careful assessment for for assuring its reliable operation as well as its mechanical integrity. In this paper we discuss the effects of the fast electromagnetic transients on the superconducting magnet system. Of particular complexity is the analysis of the quench detection system of the TF coils that can be improperly triggered by the spurious signals due to the inductive coupling with the plasma and the other active and passive magnetic field sources.