Turbine adapted maps for turbocharger engine matching (original) (raw)
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Turbocharger matching methodology for improved exhaust energy recovery
10th International Conference on Turbochargers and Turbocharging, 2012
Current engine simulation codes rely on user-input turbine maps to predict the performance of turbocharged engines. These experimentally obtained maps are limited in range as they are typically obtained through the use of an aerodynamically limited turbine loading device, the compressor. In order to extend the range of the map for simulation, several fitting techniques are utilized in order to obtain the values of efficiency and mass flow over the entire range of pressure ratio for all speeds. This investigation compares predicted turbine maps, obtained from narrow ranges of pressure ratio with more reliable, wider maps obtained experimentally for the same turbines by replacing the compressor with a dynamometer. The outcome of this investigation can be used to improve the fitting of efficiency and mass flow rate curves in engine simulation software.
Review of Turbocharger Mapping and 1D Modelling Inaccuracies with Specific Focus on Two-Stag Systems
SAE Technical Paper Series, 2015
The adoption of two stage serial turbochargers in combination with internal combustion engines can improve the overall efficiency of powertrain systems. In conjunction with the increase of engine volumetric efficiency, two stage boosting technologies are capable of improving torque and pedal response of small displacement engines. In two stage sequential systems, high pressure (HP) and low pressure (LP) turbochargers are packaged in a way that the exhaust gases access the LP turbine after exiting the HP turbine. On the induction side, fresh air is compressed sequentially by LP and HP compressors. The former is able to deliver elevated pressure ratios, but it is not able to highly compressor low flow rates of air. The latter turbo-machine can increase charge pressure at lower mass air flow and be bypassed at high rates of air flow. In fact, bypass valves and waste-gated turbines are often included in two stage boosting systems in order to regulate operations and divert flow away from the turbocharger when necessary. Bypass valves are often external to the turbocharger and wastegates valves are incorporated in the turbine housing. One-dimensional modelling approaches are considered fundamental to investigate interaction between boosting systems and internal combustion engines. In this scenario, turbomachinery performances are imposed into the model through compressor and turbine maps which are previously measured in gas stands as single stages. This procedure could not capture all the effects that occur in a system layout due to combination of heat transfer and motion of internal flow. This has a significant importance for defining HP compressor and LP turbine performances which could be influenced by swirling flows induced by the previous turbo-component in the series. Additionally, bends between the two compressors/turbines can reduce uniformity of flow and cause pressure drops at the same time. As in single turbochargers, heat transfer influences the boundary conditions which would influence performance predictions of the machine in the sequence. In this paper, a review of the available literature containing approaches and study to quantify the effects of heat transfer on turbocharger efficiency and flow non-uniformities on two stage serial turbochargers performance predictions is explored. Furthermore, an appropriate mapping strategy has been proposed which could minimize the cause of inaccuracies in predicting turbochargers performance in two-stage systems. Conclusively, a methodology for map integration into 1D models has been proposed.
EXPERIMETAL METHODOLOGIES FOR A COMPREHESIVE CHARACTERIZATIO OF AUTOMOTIVE TURBOCHARGERS
In the present paper are presented a set of experimental methodologies that allows for characterizing the main aspects necessary to proper modeling energy flows transfer in turbochargers in both design and off-design conditions. With respect to the compressor side the main off-design issue while boosting to an internal combustion engine is surge. Specific techniques for surge detection at on engine conditions with real engine installation will be described in this paper. Concerning the turbine, the three main variables necessary to model off-design performance are: turbine efficiency at off-design conditions; mechanical efficiency and heat flows within the turbocharger. The methodologies proposed in this paper provide these variables based in a combination of adiabatic and non-adiabatic tests in a gas-stand for turbochargers once have been previously determined the thermal conductances of the turbocharger materials. The conclusion of the paper offers an example of the obtained results with respect to turbine efficiency for a turbocharger characterized following proposed methodologies. ITRODUCTIO Turbocharging has been one of the keys for automotive engines improvement in the last years for both diesel and petrol powerplants. New turbocharging systems allowing higher boosting capacities have yielded to new downsized engines with lower consumption and pollutant emissions. However, current turbochargers are now constrained to harder operating conditions, including higher pulsating flow at the turbine, higher operating temperature or more likeability of surge occurrence. The most important tool used for the engine gas-exchange and boosting system development are 1D gas-dynamic models able to predict the engine flows characteristics and thus engine performance. These models need to be fed with the turbocharger information, mainly the turbine and compressor steady maps. In the lasts years, a lack of accuracy has been noticed in these models. The reason is that the phenomena mentioned above pulsating flow, heat transfer or surge; are more and more prominent and are not considered in current models. The next step to develop further turbocharger models is to establish experimental procedures to characterize these phenomena in controlled conditions. The authors have been working in the last years in new tests aimed to analyze non-steady phenomena in turbochargers showing their potential use in industrial environment.
IJERT-Analytical and Experimental Turbocharger Matching to an off-Road Engine
International Journal of Engineering Research and Technology (IJERT), 2015
https://www.ijert.org/analytical-and-experimental-turbocharger-matching-to-an-off-road-engine https://www.ijert.org/research/analytical-and-experimental-turbocharger-matching-to-an-off-road-engine-IJERTV4IS100098.pdf The demand for construction equipment vehicles in India is rising with the GDP growth one among the highest in the world. The diesel engines that power these off road vehicles have different operating cycle and conditions which are always on the demanding side, hence the engines have to be robust in construction primarily and meet all the load cycles. On the other hand the rise in fuel prices have led to increase in operating cost hence now the market is looking for more fuel efficient engines for counter the fuel price rise. This work deals with selection and matching of Turbocharger to a direct injection diesel engine which was adopted for automotive application to suite CEV vehicles. First, selection of turbine and compressor is done by some assumptions and analytical method is used to match proper turbocharger and results were validated with experimental results.
Analytical and Experimental Turbocharger Matching to an off-Road Engine
International Journal of Engineering Research and, 2015
The demand for construction equipment vehicles in India is rising with the GDP growth one among the highest in the world. The diesel engines that power these off road vehicles have different operating cycle and conditions which are always on the demanding side, hence the engines have to be robust in construction primarily and meet all the load cycles. On the other hand the rise in fuel prices have led to increase in operating cost hence now the market is looking for more fuel efficient engines for counter the fuel price rise. This work deals with selection and matching of Turbocharger to a direct injection diesel engine which was adopted for automotive application to suite CEV vehicles. First, selection of turbine and compressor is done by some assumptions and analytical method is used to match proper turbocharger and results were validated with experimental results.
Assessment of Cycle Averaged Turbocharger Maps Through One Dimensional and Mean-Line Coupled Codes
Volume 6C: Turbomachinery, 2013
Downsizing the internal combustion engine has been shown to be an effective strategy towards CO 2 emissions reduction, and downsized engines look set to dominate automotive powertrains for years to come. Turbocharging has been one of the key elements in the success of downsized internal combustion engine systems. The process of engine-turbocharger matching during the development stage plays a significant role towards achieving the best possible system performance, in terms of minimizing fuel consumption and pollutant emissions. In current industry practice, engine modeling in most cases does not consider the full unsteady analysis of the turbocharger turbine. Thus, turbocharged engine performance prediction is less comprehensive, particularly under transient load conditions. Commercial one-dimensional engine codes are capable of satisfactory engine performance predictions, but these typically assume the turbocharger turbine to be quasi-steady, hence the inability to fully resolve the pulsating flow performance. On the other hand, a one-dimensional gas dynamic turbine model is capable of simulating the pressure wave propagation in the model domain, thus serving as a powerful tool to analyze the unsteady performance. In addition, a mean-line model is able to compute the turbine power and efficiency through the conservation method and Euler's Turbomachinery Equation. However, none of these mod- * Address all correspondence to this author. eling methods have been widely implemented into commercial one-dimensional engine codes thus far. The objective of this paper is to assess the possibility of numerically producing the steady equivalent cycle averaged turbocharger turbine maps, which could be used in commercial engine codes for performance prediction. The cycle-averaged maps are obtained using a comprehensive turbocharged engine model including accurate pulsating exhaust flow performance prediction. The model is validated against experimental results and effects of flow frequency on the maps are discussed in detail.
IFAC Proceedings Volumes
Faults in the intake and exhaust path of turbocharged common rail Diesel engines can lead to an increase of emissions and performance losses. Application of turbocharger models can help to detect and diagnose more faults as standard fault detection methods. The modeling of the turbocharger for onboard fault diagnosis can be obtained by different models. The differences between an approach based on the isentropic efficiencies and an approach based on Euler's turbo-machinery equation are investigated in this paper. The two models for a GT1749MV turbocharger are parameterized with data from the engine testbed. The comparison is applied by issues of measured model inputs, number of intern parameters, parameterization effort and model accuracy. Both models are compared regarding the application for onboard diagnosis.
Control-oriented turbine power model for a variable-geometry turbocharger
Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 2017
A control-oriented model for the variable-geometry turbocharger is critical for model-based variable-geometry turbocharger control design. Typically, the variable-geometry turbocharger turbine power is modeled with a fixed mechanical efficiency of the turbocharger on the assumption of an isentropic process. The fixed-efficiency approach is an oversimplification and may lead to modeling errors because of an overpredicted or underpredicted compressor power. This leads to the use of lookup-table-based approaches for defining the mechanical efficiency of the turbocharger. Unfortunately, since the vane position of a variable-geometry turbocharger introduces a third dimension into these maps, real-time implementation requires three-dimensional interpolations with increased complexity. Map-based approaches offer greater fidelity in comparison with the fixed-efficiency approach but may introduce additional errors due to interpolation between the maps and extrapolation to extend the operatio...
Development of Off-Design Turbocharger Modelling Combined with 1-D Engine Model
Procceedings of the 18th Brazilian Congress of Thermal Sciences and Engineering, 2020
The present work aims to carry out an off-design turbocharger modelling powered by exhaust gases from a Wärtsilä 20V34SG engine. First of all, 1-D engine model was already developed in GT-Power software while considering a thermodynamic turbocharger modelling with constant isentropic efficiencies. Secondly, by using the results from 1-D engine model, the off-design turbocharger modelling is calibrated separately in EES software, taking into account compressible assumption, triangle velocities and geometric dimensions. The case study is derived from a R&D project (ANEEL PD-06483-0318/2018) that targets to cool and dehumidify the intake air at compressor's upstream through a cooling coil, thereby allowing engine's operation at reduced knocking conditions. The brake mean effective pressure (BMEP) is varied in the range of 20 to 23.45 bar, corresponding to brake power from 8.7 to 10.2 MW, respectively. With the off-design turbocharger modelling it is possible to analyze its operational behavior under higher BMEP, hence, allowing to predict some important parameters. The results showed that the turbocharger is operating within the manufacturer's limit for BMEP of 23.45 bar, presenting total-to-static isentropic efficiencies of 0.81 and 0.784 for compressor and turbine, respectively, rotational speed around 28135 RPM, pressure ratio at compressor of 4.567 and maintaining control on waste-gate valve.