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Nowadays turbocharging the internal combustion engine has become an essential tool in the automotive industry to meet downsizing technique requirements. In that context turbocharger unsteadiness is huge since both turbine and compressor work under high pulsating flow conditions, being turbocharger behavior prediction more difficult but still key for matching and predicting ICE performance. The well understanding and modeling of the occurring physical phenomena during turbocharger unsteady and off-design operation seems crucial. In this paper three small radial turbines used in turbochargers from passenger car applications have been tested under high temperature and pulsating flow conditions on the turbine side. A gas stand and a rotary valve installed on the turbine inlet have been used to reproduce pulses with desired characteristics. A beam-forming technique for pressure wave's decomposition has been used to analyze turbine performance in detail.

Nowadays turbocharging the internal combustion engine has become a key point in both the reduction of pollutant emissions and the improvement of engine performance. The matching between turbocharger and engine is difficult; some of the reasons are the highly unsteady flow and the variety of diabatic and off-design conditions the turbocharger works with. In present paper the importance of the heat transfer phenomena inside small automotive turbochargers will be analyzed. These phenomena will be studied from the point of view of internal heat transfer between turbine and compressor and with a one-dimensional approach. A series of tests in a gas stand, with steady and pulsating hot flow in the turbine side, will be modeled to show the good agreement in turbocharger enthalpies prediction. The goodness of the model will be also shown predicting turbine and compressor outlet temperatures.