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A significant amount of harmful emissions pass unreacted through catalytic after-treatment devices for IC engines before the light-off temperature is reached, despite the high conversion efficiency of these systems in fully warm conditions. Further tightening of fleet targets and worldwide emission regulations will make a faster catalyst light-off to meet legislated standards hence reduce the impact of road transport on air quality even more critical. This work investigates the effect of adding hydrogen (H2) at levels up to 2500 ppm into the exhaust gases produced by combustion of various oxygenated C2-, C4- and renewable fuel molecules blended at 20 % wt/wt with gasoline on the light-off performance of a commercially available three-way catalyst (TWC) (0.61 L, Pd/Rh/Pt - 19/5/1, 15g). The study was conducted on a modified naturally aspirated, 1.4 L, four-cylinder, direct-injected, spark-ignition engine.

In this work we studied the effects of piston bowl design on combustion in a small-bore direct-injection diesel engine. Two bowl designs were compared: a conventional, omega-shaped bowl and a stepped-lip piston bowl. Experiments were carried out in the Sandia single-cylinder optical engine facility, with a medium-load, mild-boosted operating condition featuring a pilot+main injection strategy. CFD simulations were carried out with the FRESCO platform featuring full-geometric body-fitted mesh modeling of the engine and were validated against measured in-cylinder performance as well as soot natural luminosity images. Differences in combustion development were studied using the simulation results, and sensitivities to in-cylinder flow field (swirl ratio) and injection rate parameters were also analyzed.

Aircraft icing is a significant issue for aviation safety. In this paper, recent developments for calculating the trajectory of non-spherical particles are used to determine the trajectory and impingement of ice crystals in aircraft icing scenarios. Two models are used, each formulated from direct numerical simulations, to give the drag, lift and torque correlations for various shaped particles. Previously, within the range of Reynolds number permitted in this study, it was only possible to model the trajectory and full rotational progression of cylindrical particles. The work presented in this paper allows for analysis of a wider range of ice shapes that are commonly seen in icing conditions, capturing the dynamics and behaviours specific to ice crystals. Previous limitations relate to the in ability to account for particle rotation and the dependency of force correlations on the measure of particle sphericity - which are now overcome.

Sector mesh modeling is the dominant computational approach for combustion system design optimization. The aim of this work is to quantify the errors descending from the sector mesh approach through three geometric modeling approaches to an optical diesel engine. A full engine geometry mesh is created, including valves and intake and exhaust ports and runners, and a full-cycle flow simulation is performed until fired TDC. Next, an axisymmetric sector cylinder mesh is initialized with homogeneous bulk in-cylinder initial conditions initialized from the full-cycle simulation. Finally, a 360-degree azimuthal mesh of the cylinder is initialized with flow and thermodynamics fields at IVC mapped from the full engine geometry using a conservative interpolation approach. A study of the in-cylinder flow features until TDC showed that the geometric features on the cylinder head (valve tilt and protrusion into the combustion chamber, valve recesses) have a large impact on flow complexity.

We present an approach in which we use simulation to capture the two-way coupling between the dynamics of a vehicle and that of a fluid that sloshes in a tank attached to the vehicle. The simulation is carried out in and builds on support provided by two modules: Chrono::FSI (Fluid-Solid Interaction) and Chrono::Vehicle. The dynamics of the fluid phase is governed by the mass and momentum (Navier-Stokes) equations, which are discretized in space via a Lagrangian approach called Smoothed Particle Hydrodynamics. The vehicle dynamics is the solution of a set of differential algebraic equations of motion. All equations are discretized in time via a half-implicit symplectic Euler method. This solution approach is general - it allows for fully three dimensional (3D) motion and nonlinear transients. We demonstrate the solution in conjunction with the simulation of a vehicle model that performs a constant radius turn and double lane change maneuver.

The conversion of lignocellulosic biomass to liquid fuels presents an alternative to the current production of renewable fuels for IC engines from food crops. However, realising the potential for reductions in net CO2 emissions through the utilisation of, for example, waste biomass for sustainable fuel production requires that energy and resource inputs into such processes be minimised. This work therefore investigates the combustion and emission characteristics of five intermediate platform molecules potentially derived from lignocellulosic biomass: gamma-valerolactone (GVL), methyl valerate, furfuryl alcohol, furfural and 2-methyltetrahydrofuran (MTHF). The study was conducted on a naturally aspirated, water cooled, single cylinder spark-ignition engine. Each of the platform molecules were blended with reference fossil gasoline at 20 % wt/wt.

Flash-boiling of sprays may occur when a superheated liquid is discharged into an ambient environment with lower pressure than its saturation pressure. Such conditions normally exist in direct-injection spark-ignition engines operating at low in-cylinder pressures and/or high fuel temperatures. The addition of novel high volatile additives/fuels may also promote flash-boiling. Fuel flashing plays a significant role in mixture formation by promoting faster breakup and higher fuel evaporation rates compared to non-flashing conditions. Therefore, fundamental understanding of the characteristics of flashing sprays is necessary for the development of more efficient mixture formation. The present computational work focuses on modelling flash-boiling of n-Pentane and iso-Octane sprays using a Lagrangian particle tracking technique.

This paper addresses the need for fundamental understanding of the mechanisms of fuel spray formation and mixture preparation in direct injection spark ignition (DISI) engines. Fuel injection systems for DISI engines undergo rapid developments in their design and performance, therefore, their spray breakup mechanisms in the physical conditions encountered in DISI engines over a range of operating conditions and injection strategies require continuous attention. In this context, there are sparse data in the literature on spray formation differences between conventionally drilled injectors by spark erosion and latest Laser-drilled injector nozzles. A comparison was first carried out between the holes of spark-eroded and Laser-drilled injectors of same nominal type by analysing their in-nozzle geometry and surface roughness under an electron microscope.

A study and analysis of the relation of biodiesel chemical structures to the resulting soot characteristics and soot oxidative reactivity is presented. Soot samples generated from combustion of various methyl esters, alkanes, biodiesel and diesel fuels in laminar co-flow diffusion flames are analyzed to evaluate the impact of fuel-bound oxygen in fatty acid esters on soot oxidation behavior. Thermogravimetric analysis (TGA) of soot samples collected from diffusion flames show that chemical variations in biodiesel ester compounds have an impact on soot oxidative reactivity and soot characteristics in contrast to findings reported previously in the literature. Soot derived from methyl esters with shorter alkyl chains, such as methyl butyrate and methyl hexanoate, exhibit higher reactivity than those with longer carbon chain lengths, such as methyl oleate, which are more representative of biodiesel fuels.

One of the latest advancements in injector technology is laser drilling of the nozzle holes. In this context, the spray formation and atomisation characteristics of gasoline, ethanol and 1-butanol were investigated for a 7-hole spark eroded (SE) injector and its ‘direct replacement’ Laser-drilled (LD) injector using optical techniques. In the first step of the optical investigation, high-speed spray imaging was performed in a quiescent injection chamber with global illumination using diffused Laser light. The images were statistically analyzed to obtain spray penetration, spray tip velocity and spray ‘cone’ angles. Furthermore, droplet sizing was undertaken using Phase Doppler Anemometry (PDA). A single spray plume was isolated for this analysis and measurements were obtained across the plume at a fixed distance from the nozzle exit.

The Leaner Lifted-Flame Combustion (LLFC) strategy offers a possible alternative to low temperature combustion or other globally lean, premixed operation strategies to reduce soot directly in the flame, while maintaining mixing-controlled combustion. Adjustments to fuel properties, especially fuel oxygenation, have been reported to have potentially beneficial effects for LLFC applications. Six fuels were selected or blended based on cetane number, oxygen content, molecular structure, and the presence of an aromatic hydrocarbon. The experiments compared different fuel blends made of n-hexadecane, n-dodecane, methyl decanoate, tri-propylene glycol monomethyl ether (TPGME), as well as m-xylene. Several optical diagnostics have been used simultaneously to monitor the ignition, combustion and soot formation/oxidation processes from spray flames in a constant-volume combustion vessel.

Improvements in the efficiency of internal combustion engines and the development of renewable liquid fuels have both been deployed to reduce exhaust emissions of CO2. An additional approach is to scrub CO2 from the combustion gases, and one potential means by which this might be achieved is the reaction of combustions gases with sodium borohydride to form sodium carbonate. This paper presents experimental studies carried out on a modern direct injection diesel engine supplied with a solution of dissolved sodium borohydride so as to investigate the effects of sodium borohydride on combustion and emissions. Sodium borohydride was dissolved in the ether diglyme at concentrations of 0.1 and 2 % (wt/wt), and tested alongside pure diglyme and a reference fossil diesel. The sodium borohydride solutions and pure diglyme were supplied to the fuel injector under an inert atmosphere and tested at a constant injection timing and constant engine indicated mean effective pressure (IMEP).

This paper presents a study of the combustion mechanism of hydrous and anhydrous ethanol in comparison to iso-octane and gasoline fuels in a single-cylinder spark-ignition research engine operated at 1000 rpm with 0.5 bar intake plenum pressure. The engine was equipped with optical access and tests were conducted with both Port Fuel Injection (PFI) and Direct Injection (DI) mixture preparation methods; all tests were conducted at stoichiometric conditions. The results showed that all alcohol fuels, both hydrous and anhydrous, burned faster than iso-octane and gasoline for both PFI and DI operation. The rate of combustion and peak cylinder pressure decreased with water content in ethanol for both modes of mixture preparation. Flame growth data were obtained by high-speed chemiluminescence imaging. These showed similar trends to the mass fraction burned curves obtained by in-cylinder heat release analysis for PFI operation; however, the trend with DI was not as consistent as with PFI.

Particulate emissions are of growing concern due to health impacts. Many urban areas around the world currently have particulate matter levels exceeding the World Health Organisation safe limits. Gasoline engines, especially when equipped with direct injection systems, contribute to this pollution. In recognition of this fact European limits on particulate mass and number are being introduced. A number of ways to meet these new stringent limits have been under investigation. The focus of this paper is on particulate emissions reduction through improvements in fuel delivery. This investigation is part of the author's ongoing particulate research and development that includes optical engine spray and combustion visualisation, CFD method development, engine and vehicle testing with the aim to move particulate emission development upstream in the development process.

Due to concerns regarding pollutant and CO2 emissions, advanced combustion modes that can simultaneously reduce exhaust emissions and improve thermal efficiency have been widely investigated. The main characteristic of the new combustion strategies, such as HCCI and LTC, is that the formation of a homogenous mixture or a controllable stratified mixture is required prior to ignition. The major issue with these approaches is the lack of a direct method for the control of ignition timing and combustion rate, which can be only indirectly controlled using high EGR rates and/or lean mixtures. Homogeneous Charge Progressive Combustion (HCPC) is based on the split-cycle principle. Intake and compression phases are performed in a reciprocating external compressor, which drives the air into the combustor cylinder during the combustion process, through a transfer duct. A transfer valve is positioned between the compressor cylinder and the transfer duct.

In-cylinder temperature and velocity fields were quantified simultaneously in an optically accessible, small-bore diesel engine. A technique utilizing luminescence from Pr:YAG phosphor particles aerosolized into the intake air was used for temperature determination while particle image velocimetry (PIV) on the aforementioned phosphor particles was used to simultaneously measure the velocity field. The temperature and velocity fields were measured at different points throughout the compression stroke up to −30 CAD. Systematic interference due to emission from the piston window reduced the accuracy of the measurements at crank angles closer to TDC. Single-shot simultaneous measurements of the temperature and velocity fields were made using both unheated and heated intake temperatures. In both cases, cycle-to-cycle variations in the temperature and velocity fields were visible.

The Reverse Braking Assist (RBA) feature is designed to automatically activate full braking in a backing vehicle. When this feature activates, a backing vehicle is suddenly stopped or may slide to a stop. During this process, an understanding of the driver's behavior may be useful in the design of an appropriate human-machine-interface (HMI) for the RBA. Several experimental studies were done to examine driver behavior in response to an unexpected and automatic braking event while backing [1]. Two of these studies are reported in this paper. A 7-passenger Crossover Utility Vehicle was fitted with a rear-view camera, a center-stack mounted LCD screen, and ancillary recording devices. In the first study, an object was suddenly placed in the path of a backing vehicle. The backing vehicle came to a sudden and complete stop. The visual image of the backing path on the LCD prominently showed that an obstacle was present in the backing path of the vehicle.

New emissions certification requirements for medium duty vehicles (MDV) meeting chassis dynamometer regulations in the 8,500 lb to 14,000 lb weight classes as well as heavy duty (HD) engine dynamometer certified applications in both the under 14,000 lb and over 14,000 lb weight classes employing large diameter exhaust pipes (up to 4″) have created new exhaust stream sampling concerns. Current On-Board-Diagnostic (OBD) dyno certified particulate matter (PM) requirements were/are 7x the standard for 2010-2012 applications with a planned phase in down to 3x the standard by 2017. Chassis certified applications undergo a similar reduction down to 1.75x the standard for 2017 model year (MY) applications. Failure detection of a Diesel Particulate Filter (DPF) at these low detection limits facilitates the need for a particulate matter sensor.

A single-cylinder Direct Injection Spark Ignition (DISI) engine with optical access was used to investigate the effects of ethanol/gasoline blends on in-cylinder formation of particulate matter (PM) and fuel spray characteristics. Indolene was used as a baseline fuel and two blends of 50% and 85% ethanol (by volume, balance indolene) were investigated. Time resolved thermal radiation (incandescence/natural luminosity) of soot particles and fuel spray characteristics were recorded using a high speed camera. The images were analyzed to quantify soot formation in units of relative image intensity as a function of important engine operating conditions, including ethanol concentration in the fuel, fuel injection timing (250, 300 and 320° bTDC), and coolant temperature (25°C and 90°C). Spatially-integrated incandescence was used as a metric to quantify the level of in-cylinder PM formed at the different operating conditions.

Two different implementations of Partial Flow Dilution (PFD) methodology designed for gravimetric particulate matter (PM) sampling are evaluated for applicability to light-duty chassis emissions testing. Filter PM measurements were collected and compared to constant volume sampler (CVS) full dilution tunnel PM filter measurements and other real-time PM measurement technologies, using gasoline vehicles generating a range of 0.1 to 10.0 mg/mile PM. Exhaust samples were collected for each phase of the Federal Test Procedure (FTP-75) with a fourth filter sample collected for the US06 supplemental cycle. Both PFDs satisfactorily met proportionality criteria for conventional combustion engines, but some improvements are needed for hybrid electric vehicles (HEVs). The PM mass collected scaled linearly with the CVS tunnel samples, with slopes of 1.03 and 0.74 for the two PFDs.