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Spark ignited engines are today operated more and more often under high load conditions, where one reason can be identified in the necessity of increasing the efficiency and hence reducing fuel consumption and specific CO2 emissions. Since the gasoline engine operation is inherently limited by knocking at high loads, strategies must be identified, which allow reliable identification and simulation of the appearance of this undesirable type of combustion. A new numerical model for the description of those kinds of pre-flame reactions in a CFD framework is discussed in this paper. Despite emphasis is put here on the auto-ignition effects, it will also be explained that the model is capable of supporting the engine development process in all combustion and emission related aspects.

The measurement of the particle number (PN) concentration of non-volatile particles ≻23 nm was introduced in the light-duty vehicles regulation; the heavy-duty regulation followed. Based on the findings of the Particle Measurement Program (PMP), heavy-duty inter-laboratory exercise, the PN concentration measurement can be conducted either from the full dilution tunnel with constant volume sampling (CVS) or from the partial flow dilution system (PFDS). However, there are no other studies that investigate whether the PN results from the two systems are equivalent. In addition, even the PMP study never investigated the uncertainty that is introduced at the final result from the extraction of a flow by a PN system from the PFDS. In this work we investigate the uncertainty for the three possible cases, i.e., considering a constant extracted flow from the PFDS, sending a signal with 1 Hz frequency to the PFDS, or feeding back the extracted flow to the PFDS.

Eliminating toxic exhaust emissions, amongst them particulate matter (PM), is one of the driving factors behind the increasing use of electrified vehicles. However, it is frequently overseen that PM arise not only from combustion, but from non-exhaust traffic related causes as well; in particular from the vehicle brakes, tires and the road surface. Furthermore, as electrified vehicles weigh more and typically exhibit higher torques at low speeds, their non-exhaust emissions tend to be higher than for comparable conventional vehicles, especially those generated by tires. Fortunately, tire related emissions are directly related to tire wear, so that limiting tire wear can reduce these emissions as well. This can be accomplished by intelligently modulating the vehicle torque profile in real time, to limit the operation in conditions of higher tire wear.

The effective identification and control of powertrain structure borne harmonic noise is one key for achieving the desired noise pattern in a vehicle. Much work is being done in this field to refine and develop transfer path analysis techniques suitable for application at each stage of a vehicle development program. For vehicle application, transfer path analysis and source identification techniques are in use today with varying degrees of success and application complexity. Investigation tools which are fast, do not require extensive vehicle dismantling and yet provide reliable answers, are of great value to NVH and sound quality engineers. A novel Active Path Tracking (APT) method has been developed which is fast to apply and offers immediate practical confirmation of the contributions of all identified chassis transmission paths to the vehicle interior.

Upcoming, increasingly stringent greenhouse gas (GHG) as well as emission limits demand for powertrain electrification throughout all vehicle applications. Increasing complexity of electrified powertrain architectures require an overall system approach combining modular component technology with integration and industrialization requirements when heading for further significant efficiency optimization. At the same time focus on reduced development time, product cost and minimized additional investment demand reuse of current production, machining, and assembly facilities as far as possible. Up to date additive manufacturing (AM) is an established prototype component, as well as tooling technology in the powertrain development process, accelerating procurement time and cost, as well as allowing to validate a significantly increased number of variants. The production applications of optimized, dedicated AM-based component design however are still limited.

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.

DiMethyl Ether (DME) has been known to be an outstanding fuel for combustion in diesel cycle engines for nearly twenty years. DME has a vapour pressure of approximately 0.5MPa at ambient temperature (293K), thus it requires pressurized fuel systems to keep it in liquid state which are similar to those for Liquefied Petroleum Gas (mixtures of propane and butane). The high vapour pressure of DME permits the possibility to optimize the fuel injection characteristic of direct injection diesel engines in order to achieve a fast evaporation and mixing with the charged gas in the combustion chamber, even at moderate fuel injection pressures. To understand the interrelation between the fuel flow inside the nozzle spray holes tests were carried out using 2D optically accessed nozzles coupled with modelling approaches for the fuel flow, cavitation, evaporation and the gas dynamics of 2-phase (liquid and gas) flows.

The development of low noise engines and vehicles, accompanied by the reduction of costs and development time, can be obtained only if the design engineer is supported by complex calculation tools in a concurrent engineering process. In this respect, the reduction of vibrations (passenger comfort) and of vehicle noise (accelerated pass by noise) are important targets to meet legislative limits. AVL has been developing simulation programs for the dynamic-acoustic optimization of engines and gear trains for many years. To simulate the structure-born and air-born noise behavior of engines under operating conditions, substantial efforts on the mathematical simulation model are necessary. The simulation tool EXCITE, described in this paper, allows the calculation of the dynamic-acoustic behavior of power units.

For nearly twenty years, DiMethyl Ether has been known to be an outstanding fuel for combustion in diesel cycle engines. Not only does it have a high Cetane number, it burns absolutely soot free and produces lower NOx exhaust emissions than the equivalent diesel. However, the physical properties of DME such as its low viscosity, lubricity and bulk modulus have negative effects for the fuel injection system, which have both limited the achievable injection pressures to about 500 bar and DME's introduction into the market. To overcome some of these effects, a common rail fuel injection system was adapted to operate with DME and produce injection pressures of up to 1000 bar. To understand the effect of the high injection pressure, tests were carried out using 2D optically accessed nozzles. This allowed the impact of the high vapour pressure of DME on the onset of cavitation in the nozzle hole to be assessed and improve the flow characteristics.

Light duty diesel vehicles continue to win recognition and market shares in Europe due to their convincing economy, reliability and driveability features. The diesel boom finds a fresh rationale in the CO2 emission legislation to come, however, the competitiveness of diesel cars may be impaired in future in consequence of the progression of the exhaust emission legislation and its impact on vehicle cost. This paper reviews the technologies currently pursued on the side of the engine and its subsystems, as well as the exhaust gas aftertreatment concepts required to satisfy the European legislation. An integral system approach is suggested, aiming at an optimum match of vehicle design parameters, transmission gear and the engine including aftertreatment elements and control.

The present contribution gives an overview of the use of different simulation tools for the optimization of injection parameters of a diesel engine. With a one-dimensional tool, the behavior of the mechanics and fluid dynamics of the entire injection system is calculated. This simulation provides information on the dynamic needle lift, injection rates, pressures, etc. The flow within the injector is simulated using a three-dimensional CFD tool. By use of a two-phase model, it is possible to analyze the cavitating flow inside the injector and to calculate the effective nozzle hole area as well as the exit flow characteristics. Mixture formation, combustion and pollutant formation simulation is performed adopting three-dimensional CFD. In order to provide the initial and boundary conditions for the engine CFD simulation and to optimize the engine cycle performance a one-dimensional tool is adopted.

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 zero-dimensional crank angle resolved combustion model which was developed for the analysis and prediction of combustion in compression ignition (CI) engines. The model relies on the multi zone combustion model (MZCM) approach of Hiroyasu. The main sub-models were taken from literature and extended with additional features described in this paper. A special procedure described in a previous paper is used to identify the mechanisms of the combustion process on the basis of the measured cylinder pressure trace. Based on the identified mechanisms the present work concentrates on the analysis of the causal effects that predominantly control the combustion process and the formation of NOx and Soot. The focus lies on the changes of the thermodynamic states and the composition of the reaction zones caused by different emission control strategies.

In the automotive industry, various simulation-based analysis methods have been suggested and applied to reduce the time and cost required to develop the engine structure to improve the NVH performance of powertrain. This simulation is helpful to set the engine design concept in the initial phase of the powertrain development schedules. However, when using the conventional simulation method with a uniformed force, the simulation results sometimes show different results than the test results. Therefore, in this paper, we propose a method for predicting the radiated noise level of a diesel engine using actual combustion excitation force. Based on the analytical radiated noise development target, we identify the major components of the engine that are beyond this development target by in the frequency range. The components of the problem found in this way are reflected in the engine design of the early development stage to shorten the development time.

In contrast to the well-established “standard” log-law wall function, the analytical wall function (AWF) as an advanced modelling approach has not been extensively used in the industrial computational fluid dynamics (CFD) applications. As the model was originally developed aiming at computations on relatively coarse meshes, potential stability issues may arise due to the pressure-gradient sensitivity if employing locally inappropriate mesh layers, typically associated with the complex geometry details. This work evaluates performance of the thermal AWF, as proposed by Suga [4], in conjunction with the main flow field computed employing the k-ζ-f turbulence model and the hybrid wall treatment (denoted as AWF-e) within the Reynolds-averaged Navier-Stokes (RANS) framework.

As emission regulations become tighter and tighter, equipment must evolve to be able to achieve the new standards. Also additional test requirements demand a system that is flexible and can accommodate differences both in the tests and the test facility. By that test cell equipment for chassis dynamometer as well as engine dynamometer applications is getting increasingly complex. That also will require new concepts for the design of such systems. In the past emission system design was more likely a collection and packaging process, which has interfaced various independent components. Now, the development of modern analytical emission systems requires a true holistic design process. This paper will describe the demands and the realization of a modern emission system. It can be shown that an extended effort during the design process will result in a high performance system, which still remains simple and robust.

The internal combustion engine contains several actuators to control engine performance and emissions. These are controlled within the engine ECU and follow a specific operating strategy to achieve objectives such as NOx reduction and fuel economy. However, these two goals are conflicting and a compromise is required. The operating state depends on system constraints such as engine speed, load, temperature levels, and aftertreatment system efficiency. This results in constantly changing target values to stay within the defined limits, especially the legal emission limits. The conventional approach is to use multiple operating modes. Each mode represents a specific compromise and is activated accordingly. Multiple modes are required to meet emissions regulations under all required conditions, which increases the calibration effort. This new control approach uses an artificial neural network to replace the conventional multiple mode approach.

Non-combustible particles, commonly summarized as ash, influence the lifetime performance of wall flow filters. This study aims to investigate this influence by means of simulation. An existing transient 1D+1D wall flow filter model is extended by dedicated transport balances for soot and ash (1), by a discrete cake model describing changing soot and ash compositions over the cake height (2), by a phenomenological cake filtration model (3), by dedicated cake property models (4) and by a phenomenological model capturing the radial mobility of solids within the cake (5). Results of three different types of simulations are shown. First, the various sub-models are assessed in isolated simulation configurations. The combination of these shall serve as theoretical model validation. Second, isolated loading and passive regeneration simulations are performed.

Automobile manufacturers and suppliers are under pressure to develop more efficient thermal management systems as fuel consumption and emission regulations become stricter and buyers demand greater comfort and safety. Additionally, engines must be very efficient and windows must deice and defog quickly. These requirements are often in conflict. Moreover, package styling and cost constraints severely limit the design of coolant and air conditioning systems. Simulation-based design and virtual prototyping can ensure greater product performance and quality at reduced development time and cost. The representation of the vehicle thermal management needs a scalable approach with 0-D, 1-D, and 3-D fluid dynamics, multi-body dynamics, 3-D structural analysis, and control unit simulation capabilities. Different combinations and complexities of the simulation tools are required for various phases of the product development process.

The paper describes a universally structured simulation platform which is used for the analysis and prediction of combustion in compression ignition (CI) engines. The models are on a zero-dimensional crank angle resolved basis as commonly used for engine cycle simulations. This platform represents a kind of thermodynamic framework which can be linked to single and multi zone combustion models. It is mainly used as work environment for the development and testing of new models which thereafter are implemented to other codes. One recent development task focused on a multi zone combustion model which corresponds to the approach of Hiroyasu. This model was taken from literature, extended with additional features described in this paper, and implemented into the thermodynamic simulation platform.