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1D codes are nowadays commonly used to investigate a turbocharged ICE performance, turbo-matching and transient response. The turbocharger is usually described in terms of experimentally derived characteristic maps. The latter are commonly measured using the compressor as a brake for the turbine, under steady “hot gas” tests. This approach causes some drawbacks: each iso-speed is commonly limited to a narrow pressure ratio and mass flow rate range, while a wider operating domain is experienced on the engine; the turbine thermal conditions realized on the test rig may strongly differ from the coupled-to-engine operation; a “conventional” net turbine efficiency is really measured, since it includes the effects of the heat exchange on the compressor side, together with bearing friction and windage losses.

The paper is focused on the development of a fractal combustion model, included within a whole-engine one-dimensional model (1Dime code). An extensive validation is carried out through the comparison with experimental data. The experimental activity was carried out in the combustion chamber of an optically accessible one-cylinder engine, equipped with a commercial head. Experimental data basically consisted on optical measurements which were also correlated to the instantaneous pressure inside the cylinder. Optical measurements were based on 2D digital imaging and UV chemiluminescence of radical species. The rate of chemical energy release and related parameters were evaluated from the in-cylinder pressure data using interpretation models for heat release analysis. Moreover a post-processing of the optical measurements allowed to define the mean flame radius, and propagation speeds as well, as a function of the crank angle.