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There are many anthropogenic climate change mitigation strategies being adopted worldwide. One of these is the adoption of biodiesel FAME (Fatty Acid Methyl Ester), in transportation. The fuel has been widely promoted as replacement for petroleum diesel because of its potential benefits for life cycle greenhouse gas emissions, carbon dioxide reduction and particulate matter improvements. Presently biodiesel may be made from a wide variety of starting materials, including food waste and agricultural materials such as vegetable oils and greases. The number and variety of possible starting materials continues to increase. Though, there is a limiting factor in the use of FAME, and that is cold weather operability. The regional climate can often influence FAME adoption with resultant economic and environmental implications. Often this cold temperature operability manifests itself as in vehicle fuel filter blocking.

The traditional MTPA-flux weakening control method depends on the off-line calibration and PI feedback(leading angle control method). This will cause insufficient responsiveness if the motor parameters change. This paper proposes a novel MTPA-flux weakening feedforward control strategy based on model parameter updates. To reduce the real-time calculation load, the Ferrari collocation method is used to solve the quartic equation to obtain the MTPA explicit format model, and the discrete bisection method is used to quickly solve the working point in the flux weakening stage. By judging the relationship among the target torque working line, the voltage limiting circle and the current limiting circle, the intersection point with the minimum current loss is selected as the working point. The advantages of the designed MTPA-flux weakening feedforward control strategy are verified by implementing the simulation based on a permanent magnet synchronous motor model.

Developed by Rudolph Diesel in the 1890s, the diesel powertrain is used in many applications worldwide. For significant time the engine fuel source for these engines was petroleum diesel, until new legislation regarding emission reduction and smog mitigation saw the introduction of petroleum diesel and biodiesel (Fatty acid methyl ester; FAME) blends in the early 2000s. Since then there have been many instances of filters in diesel powertrains across heavy, light and off-road platforms becoming blocked with unidentified material, for example in the United States, Northern Europe and Scandinavia. Filters are designed to remove contaminants from the fuel system and as the filter becomes plugged it restricts the fuel flow resulting in loss of engine power and eventual breakdown. Understanding The nature of the material responsible for such blockages is clearly important to the industry and has been the subject of many studies.

Focusing on the dual-mode dual-fuel (DMDF) combustion concept, a combined optimization of the piston bowl geometry with the fuel injection strategy was conducted at low, mid, and high loads. By coupling the KIVA-3V code with the enhanced genetic algorithm (GA), a total of 14 parameters including the piston bowl geometric parameters and the injection parameters were optimized with the objective of meeting Euro VI regulations while improving the fuel efficiency. The optimal piston bowl shape coupled with the corresponding injection strategy was summarized and integrated at various loads. Furthermore, the effects of the key geometric parameters were investigated in terms of organizing the in-cylinder flow, influencing the energy distribution, and affecting the emissions. The results indicate that the behavior of the DMDF combustion mode is further enhanced in the aspects of improving the fuel economy and controlling the emissions after the bowl geometry optimization.

Owing to the small size of engines and high injection pressures, it is difficult to avoid the fuel spray impingement on the combustion cylinder wall and piston head in Direct Injection Spark Ignition (DISI) engine, which is a possible source of hydrocarbons and soot emission. As a result, the droplets size and distribution are significantly important to evaluate the atomization and predict the impingement behaviors, such as stick, spread or splash. However, the microscopic behaviors of droplets are seldom reported due to the high density of small droplets, especially under high pressure conditions. In order to solve this problem, a “spray slicer” was designed to cut the spray before impingement as a sheet one to observe the droplets clearly. The experiment was performed in a constant volume chamber under non-evaporation condition, and a mini-sac injector with single hole was used.

Controllability of ignition timing and combustion phase by means of dual-fuel direct injection strategy in jet-controlled compression ignition mode were investigated in a light-duty prototype diesel engine. Blended fuel with lower reactivity was delivered in the early period of compression stroke to form the premixed charge, while diesel fuel which has higher reactivity was injected near TDC to trigger the ignition. The effects of several important injection parameters including pre-injection timing, jet-injection timing, pre- injection pressure and ratio of pre-injection in the total heat value of injected fuel were discussed. Numerical Simulation by using CFD software was also conducted under similar operating conditions. The experimental results indicate that the jet-injection timing shows robust controllability on the start of combustion under all the engine load conditions.

Although turbulence plays a critical role in engines operated within low temperature combustion (LTC) regime, its interaction with chemistry on auto-ignition at low-ambient-temperature and lean-oxygen conditions remains inadequately understood. Therefore, it is worthwhile taking turbulence-chemistry interaction (TCI) into consideration in LTC engine simulation by employing advanced combustion models. In the present study, large eddy simulation (LES) coupled with linear eddy model (LEM) is performed to simulate the ignition process in n-heptane spray under engine-relevant conditions, known as Spray H. With LES, more details about unsteady spray flame could be captured compared to Reynolds-averaged Navier-Stokes equations (RANS). With LEM approach, both scalar fluctuation and turbulent mixing on sub-grid level are captured, accounting for the TCI. A skeletal mechanism is adopted in this numerical simulation, including 41 species and 124 reactions.

The potential of diesel/gasoline RCCI combustion coupled with late intake valve closing (LIVC) and double direct injection of diesel for meeting high fuel efficiency with ultra-low emissions was investigated in this study. The study was aiming at high load operation in a heavy-duty diesel engine. Based on the reactivity stratification of RCCI combustion, the employment of double injection of diesel fuel provided concentration stratification of the high-reactivity fuel, which is to further realize effective control of the combustion process. Meanwhile, late intake valve closing (LIVC) strategy is introduced to control the maximum in-cylinder pressure and nitrogen oxides (NOx) emissions.

Dual-fuel combustion is an attractive approach for utilizing alternative fuels such as natural gas in compression-ignition internal combustion engines. In this approach, pilot injection of a more reactive fuel provides a source of ignition for the premixed natural gas/air. The overall performance combines the high efficiency of a compression-ignition engine with the relatively low emissions associated with natural gas. However the combustion phenomena occurring in dual-fuel engines present a challenge for existing turbulent combustion models because, following ignition, flame propagates through a partially-reacted and inhomogeneous mixture of the two fuels. The objective of this study is to test a new modelling formulation that combines the ability of the Conditional Moment Closure (CMC) approach to describe autoignition of fuel sprays with the ability of the G-equation approach to describe the subsequent flame propagation.

The chemical kinetic mechanism determines the ignition timing of homogeneous charge compression ignition (HCCI) engines. The correlation of the ignition delay in shock tubes and HCCI engines under different operating conditions was studied with a reduced mechanism of the primary reference fuel (PRF) composing of n-heptane and iso-octane. According to the similarity analysis of the sensitivity coefficient, the operating conditions which affect the similarity factor are recognized. The results indicate that, under the negative temperature coefficient (NTC) region of the ignition delay in shock tubes, the weight of each reaction on the ignition delay in shock tubes is similar to that in HCCI engines. The ignition delay time in HCCI engines is defined as the period from the time of start of heat release (SHR) with the HRR greater than zero to CA10. At the high equivalence ratios in shock tubes, the similarity factor at the low ambient temperatures is small.

Fuel injection and fuel-air mixture formation processes have significant influence on the performance of spark ignition gas engines. In order to study the fuel enrichment injection process in the pre-chamber of a marine gas engine, the flow field in the pre-chamber during the gas fuel injection period was investigated by the particle image velocimetry (PIV) method. An organic glass model of pre-chamber was made for optical measurement. The flow fields in the pre-chamber with four different gas injection angles were analyzed, respectively. The measurement results were qualitatively compared to the CFD calculation results as the verification of the calculation. Based on the comparison of the PIV experiment results, an optimal gas fuel injection angle was chosen. Furthermore, 3D CFD calculation models with the baseline and optimal fuel injection angles of a marine spark ignited natural gas engine were generated to calculate the working process.

As one of the most important auto-body moving parts, door hinge is the key point of door design and its accessories arrangement, also the premise of the door kinematic analysis. We proposed an effective layout procedure for door hinge and developed an intelligent system on CATIA CAA platform to execute it. One toolbar and five function modules are constructed - Axis Arrangement, Section, Parting Line, Kinematic, Hinge Database. This system integrated geometrical algorithms, automatically calculate the minimum clearances between doors, fender and hinges on sections to judge if the layout is feasible. As the sizes of the clearances are set to 0s, the feasible layout regions and extreme start/end points are shown in parts window, which help the engineer to check the parting line and design a new one. Our system successfully implemented the functions of five modules for the layout of door hinge axis and parting line based on a door hinge database.

In this work, large eddy simulation (LES) with a K-equation subgrid turbulent kinetic energy model is implemented into the CFD code KIVA3V to study the features of liquid fuel spray and combustion using gradually varying grid in a constant volume chamber. The characteristic time-scale combustion model (CTC) incorporating a turbulent timescale is adopted to predict the combustion process and the SHELL auto-ignition model is used to predict auto-ignition. Combustion is also simulated using Parallel Detailed Chemistry with Lu's n-heptane reduced mechanism (58 species), which has been added into the KIVA3V-LES code. The computational results are compared with Sandia experimental data for non-reacting and reacting cases. As a result, LES can capture the complex structure of the spray and temperature distribution as well as the trend of ignition delay and flame lift-off length variations. Better results are obtained using the Parallel Detailed Chemistry than the CTC model.

This paper presents a large eddy simulation study of the liquid spray mixing with hot ambient gas in a constant volume vessel under engine-like conditions with the injection pressure of 1500 bar, ambient density 22.8 kg/m₃, ambient temperature of 900 K and an injector nozzle of 0.09 mm. The simulation results are compared with the experiments carried out by Pickett et al., under similar conditions. Under modern direct injection diesel engine conditions, it has been argued that the liquid core region is small and the droplets after atomization are fine so that the process of spray evaporation and mixing with the air is controlled by the heat and mass transfer between the ambient hot gas and central fuel flow. To examine this hypothesis a simple spray breakup model is tested in the present LES simulation. The simulations are performed using an open source compressible flow solver, in OpenFOAM.

A large eddy simulation approach and different breakup models are used to analyze fuel injection and atomization processes in a constant volume combustion bomb. The study is focused on the influences of the subgrid turbulent kinetic energy, especially the source term induced by the fuel spray, on the droplet movement and spray characteristics. Furthermore, the influence of different subgrid scale (SGS) models, including the constant coefficient and dynamic Smagorinsky models, WALE model and the K-equation turbulent energy transport model, on fuel sprays and the turbulent dispersion of droplets are examined. Factors affecting the fuel spray are discussed based on numerical computations for various operating conditions and are compared with experimental data.

The need to meet the US 2007 emissions legislation has necessitated a change in Diesel engine technology, particularly to the fuel injection equipment (FIE). At the same time as these engine technology changes, legislation has dictated a reduction in fuel sulphur levels and there has also been increased use of fatty acid methyl esters (FAME) or biodiesel as a fuel blending component. The combination of changes to the engine and the fuel has apparently led to a sharp rise in the number of reports of field problems resulting from deposits within the FIE. The problem is usually manifested as a significant loss of power or the engine failing to start. These symptoms are often due to deposits to be found within the fuel injectors or to severe fouling of the fuel filter. The characteristics of the deposits found within different parts of the fuel system can be noticeably different.

The paper describes a novel method for calculating the residual gas fraction and the trapping efficiency in a 2 stroke engine. Assuming one dimensional compressible flow through the inlet and exhaust ports, the method estimates the instantaneous mass flowing in and out from the combustion chamber; later the residual gas fraction and trapping efficiency are estimated combining together the perfect displacement and perfect mixing scavenging models. It is assumed that when the intake port opens, the fresh mixture is pushing out the burned charge without any mixing and after a multiple of the time needed for the largest eddy to perform one rotation, the two gasses are instantly mixed up together and expelled. The result is a very simple algorithm that does not require much computational time and is able to estimate with high level of precision the trapping efficiency and the residual gas fraction in 2 stroke engines.

Working process of diesel engine refers to airflow, turbocharger, fuel injection, combustion, heat transfer and chemical reaction powers etc. Hence, it influences power output, fuel consumption, combustion noise and emissions, moreover directly influences reliability and durability of diesel engine. The working process of 6106 diesel engine is simulated by large universal internal combustion engine working process numerical simulation software GT-Power in this paper, and the effects of compression ratio, fuel supply advance angle and valve timing system on performance of diesel engine are analyzed. When valve-timing system is studied, the influence of intake valve close timing, exhaust valve open timing and valve overlap angle on performance are analyzed. On different operating conditions, the different timing of intake close and exhaust open, valve overlap were computed and analyzed. Finally, at different engine conditions, various optimum results were obtained.

It has been known from multi-zone simulations that HCCI combustion can be significantly affected by temperature stratification of the in-cylinder gas. With the same combustion timing (i.e. crank angles at 50% heat release, denoted as CA50), large temperature stratification tends to prolong the combustion duration and lower down the in-cylinder pressure-rise-rate. With low pressure-rise-rate HCCI engines can be operated at high load, therefore it is of practical importance to look into more details about how temperature stratification affects the auto-ignition process. It has been realized that multi-zone simulations can not account for the effects of spatial structures of the stratified temperature field, i.e. how the size of the hot and cold spots in the temperature field could affect the auto-ignition process. This question is investigated in the present work by large eddy simulation (LES) method which is capable of resolving the in-cylinder turbulence field in space and time.

To understand the working mechanism of the porous medium (PM) internal combustion engine, effects of a porous medium heat regenerator inserted into a combustion chamber on the turbulent flow field and fuel-air mixture formation are studied by numerical simulation. The cylindrical chamber has a constant volume, in which a disk-shaped PM insert is fixed. A simplified model for the random structure of the PM is presented, in which the PM is represented by an assembly of a great number of randomly distributed solid units. To simulate flows in the PM a Brinkman-Forchheimer-extended Darcy's equation is introduced into the numerical solver. A version of two-equation k - ε turbulence model suggested by Antohe and Lage is employed for the turbulence prediction in the PM. A spray model, in which the effects of drop breakup, collision and coalescence are taken into account, is introduced to describe spray/wall interactions.