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Technical Paper

Experimental Characterization for Modelling of Turbocharger Friction Losses

Abstract Today turbochargers are used by car manufacturers on Diesel engines and on an increasing number of gasoline engines, especially in the scope of downsizing. This component has to be well understood and modeled as simulation is widely used at every step of the development. Indeed development cost and time have to be reduced to fulfill both customers’ wishes and more stringent emissions standards. Current turbocharger simulation codes are mostly based on look-up tables (air mass flow and efficiency) given by manufacturers. This raises two points. Firstly, the characteristics are known only in the same conditions as manufacturers’ tests. Secondly, the turbine efficiency given by turbochargers manufacturers is the product of the isentropic efficiency and the turbocharger mechanical efficiency. This global efficiency is suitable for the calculation of the power transferred to the compressor.
Technical Paper

Experimental Study of Centrifugal Compressor Speed Lines Extrapolation for Automotive Turbochargers

Abstract Downsizing has nowadays become the more widespread solution to achieve the quest for reaching the fuel consumption incentive. This size reduction goes with turbocharging in order to keep the engine power constant. To reduce the development costs and to meet the ever tightening regulations, car manufacturers rely more and more on computer simulations. Thus developing accurate and predictable turbocharger models functioning on a wide range of engine life cases became a major requirement in industrial projects. In the current models, compressors and turbines are represented by look-up tables, experimentally measured on a turbocharger test bench, at steady point and high inlet turbine temperature. This method results in limited maps : on the one hand the compressor surge line and on the other hand the flow resistance curve behind the compressor. Mounted on an engine, the turbocharger encounters a wider scale of functioning points.
Technical Paper

Optimized Air Intake for a Turbocharged Engine Taking into Account Water-Cooled Charge Air Cooler Reflective Properties for Acoustic Tuning

Unsteady intake wave dynamics have a first order influence on an engine's performance and fuel economy. There is an abundant literature particularly for naturally aspirated SI engines on the subject of intake manifolds and primary runner lengths aimed to achieve a tuned intake air line. A more demanding design for today's engines is to increase efficiency to meet the requirements of lower fuel consumption and CO2 emissions. Today's tendencies are downsizing the engine to meet these demands. And for drivability purposes, the engine is combined with a turbocharger coupled with a charge air cooler. However, when the engine's displacement is reduced, it will be very dependent on its boosting system. A particularly interesting point to address corresponds to the engine's operation in the low speed range and during transients where the engine has large pumping losses and poor boost pressure. This operation point can be optimized using acoustic supercharging techniques.