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The aim of the current contribution is to develop a tool for the improvement of accuracy of turbocharger turbine simulation during matching of a turbocharger to an engine. The paper demonstrates the possibility of unsteady turbine simulation in pulsating flow caused by an internal combustion engine using the basic modules of generalized 1-D manifold solver with entities (pipes, channels) under centrifugal acceleration in general direction and under non-uniform angular speed, which has not yet been explored. The developed model extrapolates steady operation turbine maps by this way. It uses 1-D model parameters identified from steady flow experiments. Unlike the lumped-parameter standard models of turbocharger turbines, the model takes into account complete 1-D features of a turbine flow path including arbitrary shape of turbine impeller vanes.

Active regeneration experiments were performed on a Cummins 2007 aftertreatment system by hydrocarbon dosing with injection of diesel fuel downstream of the turbocharger. The main objective was to characterize the thermal oxidation rate as a function of temperature and particulate matter (PM) loading of the catalyzed particulate filter (CPF). Partial regeneration tests were carried out to ensure measureable masses are retained in the CPF in order to model the oxidation kinetics. The CPF was subsequently re-loaded to determine the effects of partial regeneration during post-loading. A methodology for gathering particulate data for analysis and determination of thermal oxidation in a CPF system operating in the engine exhaust was developed. Durations of the active regeneration experiments were estimated using previous active regeneration work by Singh et al. 2006 [1] and were adjusted as the experiments progressed using a lumped oxidation model [2, 3].

The paper deals with investigation of flow characteristics of turbocharger turbine under real operating conditions on engine by means of combination of experimental data and advanced 1-D code for combustion engine simulation. Coupling simulations tools with the results of measurements provides the engineers with data which are difficult or impossible to measure. For instance by means of a three pressure analysis (TPA) applicable on engine cylinder the engineers can obtain burn rate, valve flow and residual gas compound from measured pressure traces in cylinder and at inlet and outlet ports. A method for turbocharger turbine on engine identification similar in principle to the three pressure analysis has been applied on radial turbine with variable geometry. A new computational module has been developed to allow identification of instantaneous flow and efficiency characteristics of the turbine.

The paper deals with the investigation of turbocharger optimization procedures using amended 1-D simulation tools. The proposed method uses scaled flow rate/effficiency maps for different sizes of a radial turbine together with a fictitious compressor map. The compressor pressure ratio/efficiency map depends on compressor circumference velocity only and predicts the both compressor specific power and achievable efficiency. At the first stage of optimization, it avoids the problems of reaching choking/surge limits. It enables the designer to find a suitable turbine type under realistic unsteady conditions (pressure pulses in exhaust manifold) concerning turbine flow area. Once the optimization of turbine/compressor impeller diameters is finished, the specific compressor map is selected. The proposed method provides the fast way to the best solution even for the case of a VGT turbine. Additional features have been developed for the representation of scaled turbine and compressor maps.

The article describes the utilization of the map-less approach in simulation of single and twin scroll radial turbines. The conventional steady flow maps are not used. An unsteady 1-D model of a twin scroll turbine includes scrolls, mixing of flows upstream of the impeller, turbine wheel, leakages and outlet pipe. Developed physical turbine model was calibrated with data from experiments at specific steady flow turbocharger test bed with open loop, which enables to achieve arbitrary level of an impeller admission via throttling in separate sections. A selected twin scroll turbine was tested under full, partial flow admission of an impeller and extreme partial admission with closed section. The required number of operating points is relatively low compared with conventional steady flow maps, when the maps have to be generated for each level of an impeller admission. The calibration process of the full 1-D turbine model is described.

The mass and overall dimensions of massively downsized engines for very high bmep (up to 35 bar) cannot be estimated by scaling of designs already available. Simulation methods coupling different levels of method profoundness, as 1-D methods, e.g., GT Suite/GT Power with in-house codes for engine mechanical efficiency assessment and preliminary design of boosting devices (a virtual compressor and a turbine), were used together with optimization codes based on genetic algorithms. Simultaneously, the impact of optimum cycle on cranktrain components dimensions (especially cylinder bore spacing), mass and inertia force loads were estimated since the results were systematically stored and analyzed in Design Assistance System DASY, developed by the authors for purposes of early-stage conceptual design. General thermodynamic cycles were defined by limiting parameters (bmep, burning duration, engine speed and turbocharger efficiency only).