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The present article is concerned with the investigation of the engine noise induced by the piston slap of an actual passenger car Diesel engine. The focus is put on the coherence of piston secondary movement, impact of the piston on the cylinder liner, generated structure-borne noise excitation of the engine structure and the occurring acceleration on the engine surface. Additionally, the influence of a varying piston-pin offset and piston clearance is evaluated. The analyses are conducted using an elastohydrodynamic multi-body simulation model, taking into account geometry, stiffness and mass information of the single components as well as considering elastic and hydrodynamic behavior of the piston-liner contact. A detailed description of the simulation model will be introduced in the article. The obtained results illustrate the piston secondary motion and the related structure-borne noise on the engine surface for several piston-pin offsets and piston clearances.

The European emission legislation for two-wheeler vehicles driven by engines of ≤ 50 cm₃ is continuously developing. One of the most important issues in the near future will be the finalization of the European Commission's proposals for future steps in the emissions regulations as well as the verification of the impacts of current standards on the market. To have a basis for the discussion about these topics, the Association for Emissions Control by Catalyst (AECC) with the Institute for Internal Combustion Engines and Thermodynamics of Graz University of Technology (IVT) carried out an extensive test program to show the actual emission situation of state-of-the-art mopeds including mass and number of particulate matter as well as unregulated gaseous components. One of the main goals of these tests was to measure exhaust emissions without any modifications to the engines of standard production vehicles available on the European market.

These days a new generation of hybrid electric vehicles (HEV) are penetrating the global vehicle market - the plug-in hybrid electric vehicles (PHEVs). Compared to conventional HEVs, PHEVs have additional significant potential. They are able to improve fuel efficiency and reduce local emissions due to higher battery capacities, and they can be recharged from external outlets. Energy management has a major impact on the PHEVs performance. In this publication, an innovative operation strategy for PHEVs is presented. This is due to the fact that both increasing fuel efficiency and enhancing the vehicle's longitudinal performance requires a fine balance between the consumption of fossil and electric energy. The new operation strategy combines advanced predictive and adaptive algorithms. In contrast to the charge-sustaining strategy of HEVs, the charge-depleting mode for PHEVs is more appropriate.

To achieve future fleet CO2 emission targets, all powertrain types, including those with internal combustion engines, need to achieve higher efficiency. Next to others the reduction of friction is one contributor to increase powertrain efficiency. The piston bore interface (PBI) accounts for up to 50 % of the total engine friction losses [1]. Optimizations in this area combined with the use of low viscosity oil, which can reduce the friction of further engine sub-systems, will therefore have a high positive impact. To assess the friction of the PBI whilst considering cross effects of other relevant parameters for mechanical function (e.g. blow-by & wear) and emissions (e.g. oil consumption) AVL has established a holistic development method based around the AVL FRISC (FRIction Single Cylinder) engine with a floating liner measurement concept.

As emission limits become increasingly stringent and the price of gaseous fuels decreases, more emphasis is being placed on promoting gas engines. In the field of large engines for power generation, dual fuel combustion concepts that run on diesel/natural gas are particularly attractive. Knock in diesel/natural gas dual fuel engines is a well known yet not fully understood complex phenomenon that requires consideration in any attempt to increase load and efficiency. Thus combustion concept development requires a reliable yet robust methodology for detecting knock in order to ensure knock-free engine operation. Operating parameters such as rail pressure, start of injection and amount of diesel injected are the factors that influence oscillations in the in-cylinder pressure trace after the start of combustion. Oscillations in the pre-mixed combustion phase, or ringing, are caused by the rapid conversion of large parts of the injected diesel.

The Institute for Internal Combustion Engines and Thermodynamics, Graz University of Technology, has presented several applications of its 2-stroke LPDI (low pressure direct injection) technology in the previous years ([1], [2], [3]). In order to improve the competitiveness of the 2-stroke LPDI technology, an air cooled 50cm3 scooter application has been developed. All previous applications have been liquid cooled. This air cooled application demonstrates the EURO 4 (2017) ability of the technology and shows that the 2S-LPDI technology can also be applied to low cost air-cooled engines. Hence, the complete scooter and moped fleet can be equipped with this technology in order to fulfil both the emission standards and the COP (conformity of production) requirements of Euro 4 emission stage. The paper presents the Euro 4 Scooter results and describes the efficient conversion process of the existing carburetor engine to the LPDI version.

The release of the “Regulation No. 168/2013” for the approval and market surveillance of two- or three-wheel motorcycles and quadricycles of the European Union started a new challenge for the motorcycle industry. One goal of the European Union is to achieve emission parity between passenger cars (EURO 6) and motorcycles (EURO 5) in 2020. The hybridization of motorcycle powertrains is one way to achieve these strict legislation limits. In the automotive sector, hybridization is well investigated and has already shown improvements of fuel consumption, efficiency and emission behavior. Equally, motorcycle applications have a high potential to improve efficiency and to meet customer needs as fun to drive as well. This paper describes a methodical approach to analyze conventional motorcycles regarding the energy and power demand for different driving cycles and driving conditions. Therefore, a dynamic or forward vehicle simulation within MATLAB Simulink is used.

High-pressure direct injection (HPDI) of natural gas into the combustion chamber enables a non-premixed combustion regime known from diesel engines. Since knocking combustion cannot occur with this combustion process, an increase in the compression ratio and thus efficiency is possible. Due to the high injection pressures required, this concept is ideally suited to applications where liquefied natural gas (LNG) is available. In marine applications, the bunkering of and operation with LNG is state-of-the-art. Existing HPDI gas combustion concepts typically use a small amount of diesel fuel for ignition, which is injected late in the compression stroke. The diesel fuel ignites due to the high temperature of the cylinder charge. The subsequently injected gas ignites at the diesel flame. The HPDI gas combustion concept presented in this paper is of a monovalent type, meaning that no fuel other than natural gas is used.

Hydrogen is seen as a promising energy carrier for a future mobility scenario. Applied as fuel in IC engines with internal mixture formation, hydrogen opens up new vistas for the layout of the combustion system. The 3D CFD simulation of internal mixture formation as well as combustion helps to understand the complex in-cylinder processes and provides a powerful tool to optimize the engine's working cycle. The performance of standard simulation models for mixture formation as well as the performance of a user-defined combustion model applied in a commercial CFD-code is discussed within this article. The 3D CFD simulations are validated with measurements obtained from a thermodynamic and from an optical research engine respectively.

A reduction in CO2 emissions and consequently fuel consumption is essential in the context of future greenhouse gas limits. With respect to the thermodynamic loss analysis of an internal combustion engine, a gap between the net indicated thermal efficiency and the brake thermal efficiency is recognizable. This share is caused by friction losses, which are the focus of this research project. The parasitic loss reduction potential by replacing the mechanical water pump with an electric coolant pump is discussed in the course of this work. This is not a novel approach in light duty vehicles, whereas in commercial vehicles a rigid drive of all auxiliaries is standard. Taking into account an implementation of a 48-V power system in the short or medium term, an electrification of auxiliary components becomes feasible. The application of electric coolant pumps on an Euro VI certified 6-cylinder in-line heavy-duty diesel engine regarding fuel economy was thus performed.

As the number of different engine and vehicle concepts for powered-two wheelers is very high and will even rise with hybridization, the simulation of emissions and fuel consumption is indispensable for further development towards more environmentally friendly mobility. In this work, an adaptive artificial neural network based predictive model for emission and fuel consumption simulation of motorcycles operated in real world conditions is presented. The model is developed in Matlab and Simulink and is integrated into a longitudinal vehicle dynamic simulation whereby it is possible to simulate various and not yet measured test cycles. Subsequently, it is possible to predict real drive emissions RDE and on-road fuel consumption by a minimum of previous measurement effort.

This publication covers investigations on different 3D CFD models for the description of the spray wall and droplet-fluid interaction and the influence of these models on the mixture formation calculation results. Basic experimental investigations in a spray chamber and a flow tunnel as well as the corresponding 3D CFD simulation were conducted in order to clarify the prediction quality of the physical phenomena of spray-wall and spray-fluid interaction by the simulation. Influencing parameters such as the piston top temperature, piston bowl geometry, soot deposits on the piston top as well as flow velocity are investigated. This paper provides a direct link between the underlying simulation models of the mixture formation and actual real world combustion system development processes - underlining the importance of a close interaction of the model calibration and the development process.

In industrial processes and other power generation processes, large amounts of waste heat are often lost to the environment. The conversion of this thermal energy into mechanical work promises a significant improvement in energy-utilization, the efficiency of the overall system and, consequently, cost-effectiveness. Therefore, the use of a Rankine-Cycle is a well-established technical process. A recent research project has investigated a novel expansion machine to be integrated into such an RC-process. Primarily, the present work deals with the fluid dynamic simulation of this expander, which is based on the principle of a rotary piston engine. The aim is to develop, analyze and optimize the process and the corresponding components. Hence, a CFD-model had to be built up, which should correspond as closely as possible to the physical engine.

The advantages of 2-stroke engines, high power and low weight, are in conflict with their disadvantages, high emissions and bad fuel economy. As these disadvantages are caused by the scavenging process, a reason for the problem can be analyzed by using three dimensional computational fluid dynamics simulation (3D CFD simulation). The scavenging losses can be dramatically reduced with a high pressure fuel injection strategy. The purpose of this strategy is to prevent a fuel concentration in the incoming charge and to reduce the fuel concentration inside the exhaust system. These advantages can only be successfully exploited with the application of an optimal injection strategy. This paper covers a spray study for a gasoline direct injection (GDI) high performance 2-stroke engine using the commercial CFD Code Fluent.

For a broad acceptance of electric vehicles, the trade-off between all electric range and battery cost respectively weight represents the most important challenge. The all electric range obtained under real world conditions most often deviates significantly from the nominal value which is measured under idealized conditions. Under extreme conditions - slow traffic and demanding requirements for cabin heating or cooling - the electrical range might become less a question of spatial distance but even more of total operation time. Whereas with conventional powertrain, high flexibility of the total driving range can be obtained without sacrificing cost, with a pure battery vehicle this results in extreme high cost and weight of the energy storage. Therefore the difference between the typical daily driving range (e.g. in Germany 80-90% is below 50 km) and the minimum total range requested by most customers for acceptance of battery vehicles (200- 250 km), becomes essential.

In this study, investigations on charging strategies for motorcycle applications have been performed on the basis of modern charging concepts. These investigations had been driven by the goal of CO₂ reduction and optimization of packaging size, while maintaining the extraordinary dynamic response behavior of modern motorcycle engines. Based on experimental investigations of the boundary conditions and restrictions of motorcycle applications in contrast to automotive applications, intense experimental test bench and on the road investigations of the stationary and transient behavior of charging strategies have been performed. These investigations covered automotive state-of-the-art charged engines as well as charged motorcycle applications. With these results, simulations of the air path for stationary and transient operation were used in order to evaluate the potential of several charging strategies for motorcycle applications.

Nowadays, politicians are forced by air pollution prevention to demand zero emission vehicles (ZEV) in the form of pure electric vehicles. The poor capacity to weight factor of actual batteries compared to any kind of liquid or gaseous hydro-carbon fuel is the main reason for the retarded implementation of ZEV. Solutions offered by automobile manufacturers are mild to full hybrid powertrains based on the well established ICE platform. The difficulty of those approaches of electrification is to compete with the performance and benefit costumers expect from standard automobiles. Pure electric vehicles are rare and often disappointing regarding range and/or performance. Additionally the costs for such vehicles, which are mainly driven by the battery prices, are comparatively high, impeding their market entrance and acceptance. Low price electric city scooters are actually offered as pure electric vehicles in a wide variety of different models.

Real world operating scenarios have a major influence on emissions and fuel consumption. To reduce climate-relevant and environmentally harmful gaseous emissions and the exploitation of fossil resources, deep understanding concerning the real drive behavior of mobile sources is needed because emissions and fuel consumption of e.g. passenger cars, operated in real world conditions, considerably differ from the officially published values which are valid for specific test cycles only [1]. Due to legislative regulations by the European Commission a methodology to measure real drive emissions RDE is well approved for heavy duty vehicles and automotive applications but may not be adapted similar to two-wheeler-applications. This is due to several issues when using the state of the art portable emission measurement system PEMS that will be discussed.

Usually the power output of 50 cm₃ two wheelers is higher than necessary to reach the maximum permitted vehicle speed, making engine power restriction necessary. This publication deals with different power restriction strategies for four-stroke engines and their effect on exhaust emissions. Alternative power limitation strategies like EGR and leaning were investigated and compared with the common method of spark advance reduction to show the optimization potential for this certain engine operation conditions. From these tests, a substantial set of data showing the pros and cons in terms of emissions, combustion stability and fuel economy could be derived for each speed limiting technique.

Worldwide increasing energy consumption, decreasing energy resources and continuous restriction of emission legislation cause a rethinking in the development of internal combustion engines and fuels. Alternative renewable fuels, so called bio-fuels, have the potential to contribute to environmentally friendly propulsion systems. This study concentrates on the usage of alcohol fuels like ethanol, methanol and butanol in non-automotive high power engines, handheld power tools and garden equipment with the focus on mixture formation and cold start capability. Although bio-fuels have been investigated intensely for the use in automotive applications yet, the different propulsion systems and operation scenarios of nonautomotive applications raise the need for specific research. A zero dimensional vaporization model has been set up to calculate the connections between physical properties and mixture formation.