Engine modelling for virtual mapping. Development of a physics based cycle-by-cycle virtual engine that can be used for cyclic engine mapping applications, engine flow modelling, ECU calibration, real-time engine control or vehicle simulation studies.

After undergoing a study about current engine modelling and mapping approaches as well as the engine modelling requirements for different applications, a major problem found to be present is the extensive and time consuming mapping procedure that every engine has to go through so that all control parameters can be derived from experimental data. To improve this, a cycle-by-cycle modelling approach has been chosen to mathematically represent reciprocating engines starting by a complete dynamics crankshaft mechanism model which forms the base of the complete engine model. This system is modelled taking into account the possibility of a piston pin offset on the mechanism. The derived Valvetrain model is capable of representing a variable valve lift and phasing Valvetrain which can be used while modelling most modern engines. A butterfly type throttle area model is derived as well as its rate of change which is believed to be a key variable for transient engine control. In addition, an approximation throttle model is formulated aiming at real-time applications. Furthermore, the engine inertia is presented as a mathematical model able to be used for any engine. A spark ignition engine simulation (SIES) framework was developed in MATLAB SIMULINK to form the base of a complete high fidelity cycle-by-cycle simulation model with its major target to provide an environment for virtual engine mapping procedures. Some experimental measurements from an actual engine are still required to parameterise the model, which is the reason an engine mapping (EngMap) framework has been developed in LabVIEW, It is shown that all the moving engine components can be represented by a single cyclic variable which can be used for flow model development

Holistic simulation for integrated vehicle design

A holistic vehicle simulation capability is necessary for front-loading component, subsystem, and controller design, for the early detection of component and subsystem design flaws, as well as for the model-based calibration of powertrain control modules. The current document explores the concept of holistic vehicle simulation by means of reviewing the current trends automotive system design and available solutions in terms of model interfaces and neutral modelling environments. The review is followed by the presentation of a Simulink-based Multi- disciplinary Modelling Environment (MME) developed by the authors to accommodate simulation work across the vehicle development cycle

Internal combustion engine model for combined heat and power (CHP) systems design

A model based, energy focused, quasi-stationary waste heat driven, internal combustion engine (ICE) centred design methodology for cogeneration (heat and electricity) systems is presented. The developed parametric model could be used for system sizing, performance evaluation, and optimization. This paper presents a systematic approach to model the behaviour of the CHP system using heat recovery prediction methods. The modular, physics based modelling environment shows the power flow between the system components, with a special emphasis on the ICE subsystems, parameter identification, and model validation

On the combustion of premixed gasoline - natural gas dual fuel blends in an optical SI engine

Natural Gas (NG) is a promising alternative fuel. Historically, the slow burning velocity of NG poses significant challenges for its utilisation in energy efficient Spark Ignited (SI) engines. It has been experimentally observed that a binary blend of NG and gasoline has the potential to accelerate the combustion process in an SI engine, resulting in a faster combustion even in comparison to that of the base fuels. The mechanism of such effects remains unclear. In this work, an optical diagnosis has been integrated with in-cylinder pressure analysis to investigate the mechanism of flame velocity and stability with the addition of NG to gasoline in a binary Dual Fuel (DF) blend. Experiments are performed under a sweep of engine load, quantified by the engine intake Manifold Air Pressure (MAP) (0.44, 0.51. 0.61 Bar), and equivalence air to fuel ratio (Φ = 0.8, 0.83, 1, 1.25). NG was added to a gasoline fuelled engine in three different energy ratios 25%, 50% and 75%. The results showed that within the flamelet combustion regime, the effect of Markstein length is dominating the lean burn combustion process both from a stability and velocity prospective. The effect of the laminar burning velocity on the combustion process gradually increases as the air fuel ratio shifts from stoichiometric to fuel rich values

Model-based comparison of hybrid propulsion systems for railway diesel multiple units

In order to reduce operating costs, railway vehicle operators need to find technical solutions to improve the efficiency of railway diesel multiple units on non-electrified railway routes. This can be achieved by hybridization of diesel multiple unit propulsion systems with electrical energy storage systems to enable brake energy recuperation. After highlighting the state of the art of hybrid railway vehicles and electrical energy storage systems, a simulation model of a generic diesel multiple unit in a 3-car formation is developed and equipped with three types of hybrid power transmissions. Simulations on realistic service profiles with different driving strategies show the potential for fuel consumption reduction for the different transmission types. On a suburban service profile, a 3-car diesel multiple unit is able to achieve simulated fuel savings of up to 24.1% and up to 18.9% on a regional service profile

On the combustion of premixed gasoline—Natural gas dual fuel blends in an optical SI engine

Natural Gas (NG) is a promising alternative fuel. Historically, the slow burning velocity of NG poses significant challenges for its utilisation in energy efficient Spark Ignited (SI) engines. It has been experimentally observed that a binary blend of NG and gasoline has the potential to accelerate the combustion process in an SI engine, resulting in a faster combustion even in comparison to that of the base fuels. The mechanism of such effects remains unclear. In this work, an optical diagnosis has been integrated with in-cylinder pressure analysis to investigate the mechanism of flame velocity and stability with the addition of NG to gasoline in a binary Dual Fuel (DF) blend. Experiments were performed under a sweep of engine load, quantified by the engine intake Manifold Air Pressure (MAP) (0.44, 0.51. 0.61 bar) and equivalence air to fuel ratio (Φ = 0.8, 0.83, 1, 1.25). NG was added to a gasoline fuelled engine in three different energy ratios 25%, 50% and 75%. The results showed that within the flamelet combustion regime, the effect of Markstein length dominates the lean burn combustion process both from a stability and velocity prospective. The effect of the laminar burning velocity on the combustion process gradually increases as the air fuel ratio shifts from stoichiometric to fuel rich values

Design development and performance evaluation of ICE exhaust silencer

The noise levels generated by an unmuffled engine exhaust system can be identified as the loudest vehicle noise source. The muffler or silencer is an essential component of the internal combustion engine exhaust system, its main function is to reduce the exhaust-generated noise to an acceptably low level. Its design development is a complex process affecting the engine efficiency and thusfuel consumption, emissions and overall noise generation. This paper focuses on the design development of a muffler for a single cylinder engine application. A 1D GT-Power model of a single valve engine was developed. Additionally, an analytical muffler preliminary design methodology was introduced. The methodology provides guidelines for muffler grade selection, sizing of different components, calculation of back pressure as a function of the exhaust gas flow rate. Two custom mufflers design concepts were developed for the single cylinder engine based on the introduced analytical methodology. Two commercial single cylinder engine muffler designs available from Yanmar and Loncin were considered for the engine performance evaluation simulation. The presented combination of analytical and numerical modelling procedures can reduce the overall length of the muffler development stage by eliminating faulty design concepts and refining the muffler’s performance parameters

Co-Simulation Methods for Holistic Vehicle Design: A Comparison

Vehicle development involves the design and integration of subsystems of different domains to meet performance, efficiency, and emissions targets set during the initial developmental stages. Before a physical prototype of a vehicle or vehicle powertrain is tested, engineers build and test virtual prototypes of the design(s) on multiple stages throughout the development cycle. In addition, controllers and physical prototypes of subsystems are tested under simulated signals before a physical prototype of the vehicle is available. Different departments within an automotive company tend to use different modelling and simulation tools specific to the needs of their specific engineering discipline. While this makes sense considering the development of the said system, subsystem, or component, modern holistic vehicle engineering requires the constituent parts to operate in synergy with one-another in order to ensure vehicle-level optimal performance. Due to the above, integrated simulation of the models developed in different environments is necessary. While a large volume of existing co-simulation related publications aimed towards engineering software developers, user-oriented publications on the characteristics of integration methods are very limited. This paper reviews the current trends in model integration methods applied within the automotive industry. The reviewed model integration methods are evaluated and compared with respect to an array of criteria such as required workflow, software requirements, numerical results, and simulation speed by means of setting up and carrying out simulations on a set of different model integration case studies. The results of this evaluation constitute a comparative analysis of the suitability of each integration method for different automotive design applications. This comparison is aimed towards the end-users of simulation tools, who in the process of setting up a holistic high-level vehicle model, may have to select the most suitable among an array of available model integration techniques, given the application and the set of selection criteria

Modelling and Co-simulation of hybrid vehicles: A thermal management perspective

Thermal management plays a vital role in the modern vehicle design and delivery. It enables the thermal analysis and optimisation of energy distribution to improve performance, increase efficiency and reduce emissions. Due to the complexity of the overall vehicle system, it is necessary to use a combination of simulation tools. Therefore, the co-simulation is at the centre of the design and analysis of electric, hybrid vehicles. For a holistic vehicle simulation to be realized, the simulation environment must support many physical domains. In this paper, a wide variety of system designs for modelling vehicle thermal performance are reviewed, providing an overview of necessary considerations for developing a cost-effective tool to evaluate fuel consumption and emissions across dynamic drive-cycles and under a range of weather conditions. The virtual models reviewed in this paper provide tools for component-level, system-level and control design, analysis, and optimisation. This paper concerns the latest techniques for an overall vehicle model development and software integration of multi-domain subsystems from a thermal management view and discusses the challenges presented for future studies

Automated model based engine calibration procedure using co-simulation

The final validation and sign-off of a production powertrain control module (PCM) calibration is a time-consuming and expensive task and requires a high degree of expertise. There are two main reasons for this; firstly, the validation test is an iterative process due to the fact that calibration changes may affect the true operating point of the engine at the desired test point. Secondly, modifications to the calibration require expert knowledge of the complete control strategy so as to improve the correlation to validation data without potentially negatively impacting the correlated mapping points. This paper describes the implementation of an optimisation routine on a virtual platform in order to both reduce the requirement for experimental testing during the validation procedure, and for development of the optimisation routine itself prior to execution on the engine dynamometer. It is shown that in simulation, the optimisation routine is capable of producing an acceptable calibration within just 5 iterations, reducing the 11-week process down to just a few days. It is also concluded that there are also a number of further improvements that could be made to further improve the efficiency of this process