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This paper describes the findings of a design, simulation and test study into how to reduce particulate number (Pn) emissions in order to meet EU6c legislative limits. The objective of the study was to evaluate the Pn potential of a modern 6-cylinder engine with respect to hardware and calibration when fitted to a full size SUV. Having understood this capability, to redesign the combustion system and optimise the calibration in order to meet an engineering target value of 3×1011 Pn #/km using the NEDC drive cycle. The design and simulation tasks were conducted by JLR with support from AVL. The calibration and all of the vehicle testing was conducted by AVL, in Graz. Extensive design and CFD work was conducted to refine the inlet port, piston crown and injector spray pattern in order to reduce surface wetting and improve air to fuel mixing homogeneity. The design and CFD steps are detailed along with the results compared to target.

In this paper, a recently improved Computational Fluid Dynamics (CFD) methodology for virtual prototyping of the heat treatment of cast aluminum parts, above most of cylinder heads of internal combustion engines (ICE), is presented. The comparison between measurement data and numerical results has been carried out to simulate the real time immersion quenching cooling process of realistic cylinder head structure using the commercial CFD code AVL FIRE®. The Eulerian multi-fluid modeling approach is used to handle the boiling flow and the heat transfer between the heated structure and the sub-cooled liquid. While for the fluid region governing equations are solved for each phase separately, only the energy equation is solved in the solid region. Heat transfer coefficients depend on the boiling regimes which are separated by the Leidenfrost temperature.

Particulate emission reduction has long been a challenge for diesel engines as the diesel diffusion combustion process can generate high levels of soot which is one of the main constituents of particulate matter. Gasoline engines use a pre-mixed combustion process which produces negligible levels of soot, so particulate emissions have not been an issue for gasoline engines, particularly with modern port fuel injected (PFI) engines which provide excellent mixture quality. Future European and US emissions standards will include more stringent particulate limits for gasoline engines to protect against increases in airborne particulate levels due to the more widespread use of gasoline direct injection (GDI). While GDI engines are typically more efficient than PFI engines, they emit higher particulate levels, but still meet the current particulate standards.

Mechanical variable valve systems are being increasingly used for modern combustion engines. It is typical for such systems that the cam and valve are connected via intermediate levers. Different maximum valve lifts and duration can be achieved with the same cam profile. The intermediate levers increase the system inertia and reduce the overall stiffness. Such systems offer more flexibility, but it is more complex to create optimal design compared to the conventional systems. In this paper a new kinematic design methodology for a CVVL (Continuously Variable Valve Lift) system is presented. Additionally, dynamic analysis of the valve train system is performed. The investigated valve train is completely developed and patented by OEM. The main characteristic of the CVVL system is a set of intermediate levers between the cam and the finger follower like ( 1 , 2 ). One cam drives two intake valves over a set of levers.

The target of dynamic simulation is to investigate complex engine dynamic behavior in the whole speed range under different loading conditions in the most effective way during Engine Development Process (EDP). AVL has developed a method for transient run-up analysis by using the simulation tool AVL EXCITE. The main objective of this new method is the controlled speed increase by defining a speed ramp. Transient run-up analysis is of interest for different kind of analysis during the EDP, such as crankshaft dynamics and strength, low frequency vibration analysis, bracket strength and durability analysis, acoustic analysis, etc. By using this method the time required for simulations and thus the whole project duration is significantly reduced. Conventionally the speed range is divided in single speed steps and for each speed a separate transient simulation has to be performed. The number of these simulations depends on the required speed resolution.

The paper describes a new methodology for a closed loop driving style detection, a vehicle driveability character evaluation and a control unit for an adaptation of the vehicle character according to the driving style. During driving the vehicle character is adapted to the driver, using the potential of modern torque based drive by wire engine control systems of gasoline and diesel engines. The methodology leads to a completely new human - vehicle interaction, the driver creates his own unique vehicle character. The vehicle owner is able to form a mass produced vehicle according to his demands. A typical drawback of globalisation, a loss of identification between owner and product can be avoided by the presented methodology. The basic structure of the evaluation and control strategies are shown as well as objective and subjective results of increased driving pleasure and higher driver identification due to increased sportiness and spontaneity up to 100%.

Commonly, the spray process in Direct Injection (DI) diesel engines is modeled with the Euler Lagrangian discrete droplet approach which has limited validity in the dense spray region, close to the injector nozzle hole exit. In the presented research, a new reactive spray modelling method has been developed and used within the 3D RANS CFD framework. The spray process was modelled with the Euler Eulerian multiphase approach, extended to the size-of-classes approach which ensures reliable interphase momentum transfer description. In this approach, both the gas and the discrete phase are considered as continuum, and divided into classes according to the ascending droplet diameter. The combustion process was modelled by taking into account chemical kinetics and by solving general gas phase reaction equations.

Modern powertrain noise investigation in the development process and during trouble shooting is a combination of experiment and simulation. In simulation in recent years main focus was set on model completeness, consideration of all excitation mechanisms and efficient and stabile numerical algorithms. By that the total response of the virtual powertrain is already comparable to the overall noise level of the real powertrain. Actual challenge is to trace back the overall response to its main excitation and noise generating mechanism as well as to their main driving parameters to support the engineer not only in reaching absolute values, but also to derive the root cause of a response or potential problem and to get hints on how to improve the specific behavior. Approaches by parameter sensitivity studies are time consuming and not unambiguous.

In recent years, more attentions have been paid to stringent legislations on fuel consumption and emissions. Turbocharged downsized gasoline direct injection (DI) engines are playing an increasing important role in OEM’s powertrain strategies and engine product portfolio. Dongfeng Motor (DFM) has developed a new 1.0 liter 3-cylinder Turbocharged gasoline DI (TGDI) engine (hereinafter referred to as C10TD) to meet the requirements of China 4th stage fuel consumption regulations and the China 6 emission standards. In this paper, the concept of the C10TD engine is explained to meet the powerful performance (torque 190Nm/1500-4500rpm and power 95kW/5500rpm), excellent part-load BSFC and NVH targets to ensure the drivers could enjoy the powerful output in quiet and comfortable environment without concerns about the fuel cost and pollution.

This paper describes a numerical study of the effect of hollow crankshafts on crankshaft local strength and durability as well as slider bearing contact behavior. Crankshaft dynamic simulation for durability is still a challenging task, although numerical methods are already worldwide established and integrated part of nearly every standard engine development process. Such standard methods are based on flexible multi-body dynamic simulation, combined with Finite Element analysis and multi-axial fatigue evaluation. They use different levels of simplification and consider the most influencing phenomena relevant for durability. Lightweight design and downsizing require more and more detailed methods due to higher deformation of the crankshaft. This is especially true for hollow shafts, as present in motorsport design or aerospace applications, but also for standard engine having high potential for significant weight savings.

The acoustics of automotive intake and exhaust systems is typically modeled using linear acoustics or gas-dynamics simulation. These approaches are preferred during basic sound design in the early development stages due to their computational efficiency compared to complex 3D CFD and FEM solutions. The linear acoustic method reduces the component being modelled to an equivalent acoustic two-port transfer matrix which describes the acoustic characteristic of the muffler. Recently this method was used to create more detailed and more accurate models based on a network of 3D cells. As the typical automotive muffler includes perforated elements and sound absorptive material, this paper demonstrates the extension of the 3D linear acoustic network description of a muffler to include the aforementioned elements. The proposed method was then validated against experimental results from muffler systems with perforated elements and sound absorptive material.

The present work introduces an innovative mechanistically based 0D spray model which is coupled to a combustion model on the basis of an advanced mixture controlled combustion approach. The model calculates the rate of heat release based on the injection rate profile and the in-cylinder state. The air/fuel distribution in the spray is predicted based on momentum conservation by applying first principles. On the basis of the 2-zone cylinder framework, NOx emissions are calculated by the Zeldovich mechanism. The combustion and emission models are calibrated and validated with a series of dedicated test bed data specifically revealing its capability of describing the impact of variations of EGR, injection timing, and injection pressure. A model based optimization is carried out, aiming at an optimum trade-off between fuel consumption and engine-out emissions. The findings serve to estimate an economic optimum point in the NOx/BSFC trade-off.

In recent years concern has arisen over a new combustion anomaly, which was not commonly associated with naturally aspirated engines. This phenomenon referred to as Low-Speed Pre-Ignition (LSPI), which often leads to potentially damaging peak cylinder pressures, is the most important factor limiting further downsizing and the potential CO2 benefits that it could bring. Previous studies have identified several potential triggers for pre-ignition where engine oil seems to have an important influence. Many studies [1], [2] have reported that detached oil droplets from the piston crevice volume lead to auto-ignition prior to spark ignition. Furthermore, wall wetting and subsequently oil dilution [3] and changes in the oil properties by impinging fuel on the cylinder wall seem to have a significant influence in terms of accumulation and detachment of oil-fuel droplets in the combustion chamber.

This paper presents the results of part of the research activity carried out by the Politecnico di Torino and AVL List GmbH as part of the European Community InGAS Collaborative Project. The work was aimed at developing a combustion system for a mono-fuel turbocharged CNG engine, with specific focus on performance, fuel economy and emissions. A numerical and experimental analysis of the jet development and mixture formation in an optically accessible, single cylinder engine is presented in the paper. The experimental investigations were performed at the AVL laboratories by means of the planar laser-induced fluorescence technique, and revealed a cycle-to-cycle jet shape variability that depended, amongst others, on the injector characteristics and in-cylinder backpressure. Moreover, the mixing mechanism had to be optimized over a wide range of operating conditions, under both stratified lean and homogeneous stoichiometric modes.

A calibration and validation workflow will be presented in this paper, which utilizes common static global models for fuel consumption, NOx and soot. Due to the applicability for warm-up tests, e. g. New European Driving Cycle (NEDC), the models need to predict the temperature influence and will be fitted with measuring data from a conditioned engine test bed. The applied model structure - consisting of a number of global data-based sub-models - is configured especially for the requirements of multi-injection strategies of common rail systems. Additionally common global models for several constant coolant water temperature levels are generated and the workflow tool supports the combination and segmentation of global nominal map with temperature correction maps for seamless and direct ECU setting.

The reduction of acoustic excitation due to piston slap as well as friction loss power and seizure are main issues when simulating the oil film lubricated piston - cylinder contacts of internal combustion engines. For a correct representation of the contact conditions between a piston skirt and a cylinder liner surface both the dynamics of the contacting flexible bodies, the shape of the contacting surfaces, the amount of available oil and the properties of the lubricant itself play important roles. Besides an appropriate representation of the hydrodynamic load carrying capacity using an averaged Reynolds equation with laminar flow conditions, the simulation has to use an appropriate asperity model to consider the mixed lubrication condition. The lubricant properties are in particular influenced by its thermal conditions.

Engine simulation can be performed using model approaches of different depths in capturing physical effects. The present paper presents a comprehensive comparison study on seven different engine models. The models range from transient 1D cycle resolved approaches to steady-state non-dimensional maps. The models are discussed in the light of key features, amount and kind of required input data, model calibration effort and predictability and application areas. The computational performance of the different models and their capabilities to capture different transient effects is investigated together with a vehicle model under real-life driving conditions. In the trade-off field of model predictability and computational performance an innovative approach on crank-angle resolved cylinder modeling turned out to be most beneficial.

Wet clutches drag loss simulation is essentially linked to the clutch friction surface patterns in addition to the main geometry and conditions of the interface (relative speed, separation, inner and outer radius, viscosity and boundary pressures). The clutch patterns promote cooling flow and micro-hydrodynamic effects to aid clutch separation but greatly complicate the simulation of drag loss during separation. These drag losses are important in understanding the system losses as well as finding the most effective clutch cooling strategy. Typical clutch models either only consider simple patterns, such as radial grooves, or require significant simulation efforts to evaluate. Additionally, many simple models require calibration to measurement of the actual clutch they try to model before they provide a useful model.

Despite the increasingly stringent emissions legislation, users and owners of commercial diesel vehicles are continually demanding that each new engine generation is more economical than the previous one. This is especially important for commercial vehicles where the majority of engines are in the 1-2ltr./cyl. class. The demands are being reflected in new engine designs with lower friction and improved structural stiffness, together with fuel systems having increased pressure capability, higher spill rates, injection rate shaping and advanced control features. These fuel system requirements have led to a variety of new fuel injection systems and in the search for increased injection pressure these fuel systems have placed greater demands on the engine, especially in areas such as the cylinder head and fuel system drive, sometimes with adverse effects on the combustion and fuel injection system induced mechanical noise.

Beside the automotive industry, where 2-cylinder inline engines are catching attention again, twin-cylinder configurations are quite usual in the small engine world. From stationary engines and range-extender use to small motorcycles up to big cruisers and K-Cars this engine architecture is used in many types of applications. Because of very good overall packaging, performance characteristics and not least the possibility of parts-commonality with 4-cylinder engines nearly every motorcycle manufacturer provides an inline twin in its model range. Especially for motorcycle applications where generally the engine is a rigid member of the frame and vibrations can be transferred directly to the rider an appropriate balancing system is required.