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Catalyzed Diesel Particulate Filters (CDPFs) continue to be an important emission control solution and are now also expanding to include additional functionalities such as gas species oxidation (such as CO, hydrocarbons and NO) and even storage phenomena (such as NOx and NH3 storage). Therefore an in depth understanding of the coupled transport - reaction phenomena occurring inside a CDPF wall can provide useful guidance for catalyst placement and improved accuracy over idealized effective medium 1-D and 0-D models for CDPF operation. In the present work a previously developed 3-D simulation framework for porous materials is applied to the case of NO-NO2 turnover in a granular silicon carbide CDPF. The detailed geometry of the CDPF wall is digitally reconstructed and micro-simulation methods are used to obtain detailed descriptions of the concentration and transport of the NO and NO2 species in the reacting environment of the soot cake and the catalyst coated pores of the CDPF wall.

The physical 1-D model of a radial turbine consists of a set of gas ducts featuring total pressure and/or temperature changes and losses. Therefore, the wave propagation and filling/emptying plays a significant role if a turbine is subjected to unsteady gas flow. The results of unsteady turbine simulation using the basic modules of generalized 1-D manifold solver in GT Power are demonstrated. The turbine model calibration parameters can be identified by means of 1-D steady model used in optimization code loop. The examples of model results are compared to steady flow map predictions of turbine efficiency and engine pumping loop work. The model may be used for prediction of turbine data in out-of-design points as presented in the paper. The other important role of a model, however, is an accurate evaluation of turbine parameters from pressure and speed measurements at an engine in operation.

The paper deals with dynamics of hybrid propulsion system with electric power divider. The physical laboratory model was chosen as example. Mathematical model for transient phenomena during accelerating period of the hybrid vehicle using electric power divider was developed. The accelerating period is divided into three parts. During the first part from stand condition to very low car velocity is the vehicle driven only by the energy from battery. During the second part the battery is totally off and only the combustion engine drives the vehicle. The engine is controlled by ASR system not to bring the vehicle into slipping by getting over the adhesion. In the third part of accelerating period the combustion engine power and revolutions are controlled to get minimum fuel consumption. The simulation can help to find good strategy of the powertrain control.

The new simulation tool consists of an iterative loop of a 3-D code in parallel to a 1-D code that is employed to simulate transient engine cycles. The 1-D code yields the basic pattern of initial and boundary conditions and the 3-D simulations at several typical engine operating points are used to crosscheck the performance as well as aid in the model calibration. A flexible regression model of the fuel burn rate and the associated ROHR has been developed in conjunction with the 3-D simulations using a combination of three added Vibe functions. The emissions at the end of the expansion stroke are also predicted. The parameters of the Vibe functions and emissions are found via nonlinear regression based on state parameters such as engine speed, relative A/F ratio, EGR/rest gas contents, injection timings, etc. Additional 3-D simulations that are made at specific engine operating points complement this compact burn rate parameter library.

In the near future the effort on the development of exhaust gas treatment systems must be increased to meet the stringent emission requirements. If the relevant physical and chemical models are available, the numerical simulation is an important tool for the design of these systems. This work presents a CFD model that allows to cover the full range of applications in this area. After a detailed presentation of the theoretical background and the modeling strategies results for the simulation of a close-coupled catalyst are shown. The presented model is also applied to the oxidation of nitrogen oxides, to a diesel particle filter and a fuel-cell reformer catalyst.

Active vibration reduction for lightweight structures has attracted more and more attention in automotive industries. In this paper, reduced-order controllers are designed based on H∞ techniques to realize vibration reduction. A finite element model of piezo-based smart structure is constructed from which a nominal model containing 5 modes and validation model containing 10 modes are extracted. A mixed-sensitivity robust H∞ controller is firstly designed based on the nominal structural model. Considering the ease of controller deployment, an order reduction for the controller is then exploited using balanced truncation method. The effectiveness of the reduced-order controller is finally verified on the validation model via system simulations.

Accurate simulation tools are needed for rapid and cost effective engine development in order to meet ever tighter pollutant regulations for future internal combustion engines. The formation of pollutants such as soot and NOx in Diesel engines is strongly influenced by local concentration of the reactants and local temperature in the combustion chamber. Therefore it is of great importance to model accurately the physics of the injection process, combustion and emission formation. It is common practice to approximate Diesel fuel as a single compound fuel for the simulation of the injection and combustion process. This is in many cases sufficient to predict the evolution of the in-cylinder pressure and heat release in the combustion chamber. The prediction of soot and NOx formation depends however on locally component resolved quantities related to the fuel liquid and gas phase as well as local temperature.

The EU emission standards for new rail Diesel engines are becoming even more stringent. EGR and SCR technologies can both be used to reduce NOx emissions; however, the use of EGR is usually accompanied by an increase in PM emissions and may require a DPF. On the other hand, the use of SCR requires on-board storage of urea. Thus, it is necessary to study these trade-offs in order to understand how these technologies can best be used in rail applications to meet new emission standards. The present study assesses the application of these technologies in Diesel railcars on a quantitative basis using one and three dimensional numerical simulation tools. In particular, the study considers a 560 kW railcar engine with the use of either EGR or SCR based solutions for NOx reduction. The NOx and PM emissions performances are evaluated over the C1 homologation cycle.

Results from numerical computations performed to represent the transient behavior of vaporizing sprays injected into a constant volume chamber and into a High Speed Direct Injection combustion chamber are presented. In order to describe the liquid phase, a new model has been developed from ideas brought forward by recent experimental results (Siebers, 1999) and numerical considerations (Abraham, 1999). The liquid penetration length is given by a 1D model which has been validated on a large number of experiments. In the 3D calculation, break-up, vaporization, drag, collision and coalescence are not modeled. The mass, momentum and energy transfers from the liquid to the gas phase are imposed from the nozzle exit surface to the liquid penetration length. This model enables us to reach time step and grid-independent results. The gas penetrations obtained with the model are checked against experimental results in a constant volume chamber (Verhoeven et al., 1998).

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.

This work presents development and results of experimental and numerical investigations of an advanced ignition system with a scavenged pre-chamber for a natural gas fueled engine with a bore of 102 mm and stroke of 120 mm. Two combustion concepts are taken into account. The lean burn concept is used to minimize engine out emissions of nitric oxides (NOx) and to achieve high thermal efficiency at low load. The in-house designed scavenged pre-chamber enables the engine to be operated up to the air-excess ratio (lambda) of 2. A stoichiometric (lambda=1) operation is also possible. It is compatible with a three-way catalyst concept, at high load and potentially transient modes and can provide as high as possible engine power density. The influence of the scavenged pre-chamber volume on the combustion and performance within the range of the operational points of the naturally aspirated engine is presented in this paper.