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An advanced low heat rejection engine concept has successfully completed a 100 hour endurance test. The combustion chamber components were insulated with thermal barrier coatings. The engine components included a titanium piston, titanium headface plate, titanium cylinder liner insert, M2 steel valve guides and monolithic zirconia valve seat inserts. The tribological system was composed of a ceramic chrome oxide coated cylinder liner, chrome carbide coated piston rings and an advanced polyolester class lubricant. The top piston compression ring Included a novel design feature to provide self-cleaning of ring groove lubricant deposits to prevent ring face scuffing. The prototype test engine demonstrated 52 percent reduction in radiator heat rejection with reduced intake air aftercooling and strategic forced oil cooling.

The methodology for predicting the transient mixing rate is presented for a direct injection, quiescent chamber diesel. The mixing process is modeled as a zero-dimensional, large-scale phenomena which accounts for injection rate, cylinder geometry, and engine operating condition. As a demonstration, two different injection schemes were investigated for engine speeds of 1600, 2100, and 2600 rpm. In the first case, the air-fuel ratio was fixed while the injection rate was allowed to vary, but for the second case, the injection duration was fixed and the air-fuel ratio was allowed to vary. For the former case, the resulting mixing rate was also compared with the experimentally determined fuel burning rate. These two quantities appeared to be correlated in some manner for the various engine speeds under investigation.

High-speed video of combustion processes and cylinder pressure traces were obtained from a single-cylinder optical-accessible engine with a production four-valve cylinder head to study the mixture formation and flame propagation characteristics at near-stoichiometric start condition. Laser-sheet Mie-scattering images were collected for liquid droplet distributions inside the cylinder to correlate the mixture formation process with the combustion results. A dual-stream (DS) injector and a quad-stream (QS) injector were used to study the spray dispersion effect on engine starting, under different injection timings, throttle valve positions, engine speeds, and intake temperatures. It was found that most of the fuel under open-valve injection (OVI) conditions entered the cylinder as droplet mist. A significant part of the fuel droplets hit the far end of the cylinder wall at the exhaust-valve side.

The objective of this work is to develop a strategy to reduce the penalties in the diesel engine performance, fuel economy and HC and CO emissions, associated with the operation in the low temperature combustion regime. Experiments were conducted on a research high speed, single cylinder, 4-valve, small-bore direct injection diesel engine equipped with a common rail injection system under simulated turbocharged conditions, at IMEP = 3 bar and engine speed = 1500 rpm. EGR rates were varied over a wide range to cover engine operation from the conventional to the LTC regime, up to the misfiring point. The injection pressure was varied from 600 bar to 1200 bar. Injection timing was adjusted to cover three different LPPCs (Location of the Peak rate of heat release due to the Premixed Combustion fraction) at 10.5° aTDC, 5 aTDC and 2 aTDC. The swirl ratio was varied from 1.44 to 7.12. Four steps are taken to move from LTC to ALTC.

The high temperature tribology issue for uncooled Low Heat Rejection (LHR) diesel engines where the cylinder liner piston ring interface exceeds temperatures of 225°C to 250°C has existed for decades. It is a problem that has persistently prohibited advances in non-watercooled LHR engine development. Though the problem is not specific to non-watercooled LHR diesel engines, it is the topic of this research study for the past two and one half years. In the late 1970s and throughout the 1980s, a tremendous amount of research had been placed upon the development of the LHR diesel engine. LHR engine finite element design and cycle simulation models had been generated. Many of these projected the cylinder liner piston ring top ring reversal (TRR) temperature to exceed 540°C[1]. In order for the LHR diesel to succeed, a tribological solution for these high TRR temperatures had to be developed.

An advanced low heat rejection engine concept has been selected based on a trade-off between thermal insulating performance and available technology. The engine concept heat rejection performance is limited by available ring-liner tribology and requires cylinder liner cooling to control the piston top ring reversal temperature. This engine concept is composed of a titanium piston, headface plate and cylinder liner insert with thermal barrier coatings. Monolithic zirconia valve seat inserts, and thermal barrier coated valves and intake-exhaust ports complete the insulation package. The tribological system is composed of chrome oxide coated cylinder, M2 steel top piston ring, M2 steel valve guides, and an advanced polyol ester class lubricant.

Several mechanisms are discussed to understand the formation of both regulated and unregulated emissions in a high speed, direct injection, single cylinder diesel engine using low sulphur diesel fuel. Experiments were conducted over a wide range of injection pressures, EGR rates, injection timings and swirl ratios. The regulated emissions were measured by the standard emission equipment. Unregulated emissions such as aldehydes and ketones were measured by high pressure liquid chromatography and hydrocarbon speciation by gas chromatography. Particulate mass was measured with a Tapered Element Oscillating Microbalance (TEOM). Analysis was made of the sources of different emission species and their relationship with the combustion process under the different operating conditions. Special attention is given to the low temperature combustion (LTC) regime which is known to reduce both NOx and soot. However the HC, CO and unregulated emissions increased at a higher rate.

A better understanding is needed of the electrostatic rotating bell (ESRB) application of metallic basecoat paint to automobile exteriors in order to exploit their high transfer efficiency without compromising the coating quality. This paper presents the initial results from experimental investigation of sprays from an ESRB which is designed to apply water-borne paint. Water was used as paint surrogate for simplicity. The atomization and transport regions of the spray were investigated using laser light sheet visualizations and phase Doppler particle analyzer (PDPA). The experiments were conducted at varying levels of the three important operating parameters: liquid flow rate, shaping-air flow rate, and bellcup rotational speed. The results show that bellcup speed dominates atomization, but liquid and shaping-air flow rate settings significantly influence the spray structure. The visualization images showed that the atomization occurs in ligament breakup regime.

The flow structure inside the catalytic converter of gasoline engines is very important for consideration of the catalyst light-off condition, converter durability and conversion efficiency. However, the available experimental data under actual engine exhaust conditions are quite limited due to its complicated configuration, critical operating conditions and difficult optical access. Therefore, an experimental study was performed, using laser Doppler velocimetry technique, to measure the velocity distributions inside two production dual-monolith catalytic converters fitted on a firing gasoline engine over several engine operating conditions. This paper reports the normal velocity characteristics measured in a plane 1 mm away from the front surface of first monolith. A small fraction of titanium (IV) isopropoxide was dissolved in gasoline for generating titanium dioxide seeding particles during the engine combustion.

In our prior analytical work concerning a finite element methodology for thermal stress analysis of minimum cooled low heat rejection (LHR) engine cylinder heads, a very fine mesh with strict aspect ratio and element density criteria was used. In this current study, these criteria were relaxed and two other finite element models with different element densities were used to solve the same thermal stress problem. The thermal and stress results of the relaxed models are compared to those of the earlier very fine mesh results. It is the aim of this paper to show in a semi-quantified manner, how mesh density can affect thermal stress solutions in LHR engine heads. Hopefully this will enable other analysts working in this area to make some judgement on mesh density before starting an actual modelling effort, resulting in a savings of time and manpower resources.

The applicability of the Ionic Current sensing method in production application is severely limited by the extent of cycle-to-cycle variations in the signal trace. In an attempt to investigate the sources for these cyclic signal fluctuations, experiments were conducted on a single cylinder 4-stroke, propane-operated engine. The ionic current signal was measured at two locations. The flame development phase in the vicinity of the spark plug gap was optically monitored by means of a high-speed CCD camera. The results showed that only the second part of the Ionic Current signal is directly impacted by cyclic variations in combustion parameters. The optical results provided evidence that the characteristics of the early flame development phase have a strong impact on the features in the first part of the signal.

The direct injection gasoline spray-wall interaction was characterized inside a heated pressurized chamber using various visualization techniques, including high-speed laser-sheet macroscopic and microscopic movies up to 25,000 frames per second, shadowgraph, and doublespark particle image velocimetry. Two hollow cone high-pressure swirl injectors having different cone angles were used to inject gasoline onto a heated plate at two different impingement angles. Based on the visualization results, the overall transient spray impingement structure, fuel film formation, and preliminary droplet size and velocity were analyzed. The results show that upward spray vortex inside the spray is more obvious at elevated temperature condition, particularly for the wide-cone-angle injector, due to the vaporization of small droplets and decreased air density. Film build-up on the surface is clearly observed at both ambient and elevated temperature, especially for narrow cone spray.

Because of their robustness and cost performance, multi-hole gasoline injectors are being adopted as the direct injection (DI) fuel injector of choice as vehicle manufacturers look for ways to reduce fuel consumption without sacrificing power and emission performance. To realize the full benefits of direct injection, the resulting spray needs to be well targeted, atomized, and appropriately mixed with charge air for the desirable fuel vapor concentration distributions in the combustion chamber. Ethanol and ethanol-gasoline blends synergistically improve the turbo-charged DI gasoline performance, especially in down-sized, down-sped and variable-valve-train engine architecture. This paper presents the spray imaging results from two multi-hole DI gasoline injectors with different design, fueled with pure ethanol (E100) or gasoline (E0), under homogeneous and stratified-charge conditions that represent typical engine operating points.

Requirements for reduced fuel consumption with simultaneous reductions in regulated emissions require more efficient operation of Spark Ignited (SI) engines. An advanced valvetrain coupled with Gasoline Direct injection (GDi) provide an opportunity to simultaneously reduce fuel consumption and emissions. Work on a flex fuel GDi engine has identified significant potential to reduce throttling by using Early Intake Valve Closing (EIVC) and Late Intake Valve Closing (LIVC) strategies to control knock and load. High loads were problematic when operating on gasoline for particulate emissions, and low loads were not able to fully minimize throttling due to poor charge motion for the EIVC strategy. The use of valve deactivation was successful at reducing high load particulate emissions without a significant airflow penalty below 3000 RPM. Valve deactivation did increase the knocking tendency for knock limited fuels, due to increased heat transfer that increased charge temperature.

Signals indicative of in-cylinder combustion have been under investigation for the control of diesel engines to meet stringent emission standards and other production targets in performance and fuel economy. This paper presents the results of an investigation on the use of the ion current signal for the close loop control of a heavy duty four cylinder turbocharged diesel engine equipped with a common rail injection system. A correlation is developed between the start of ion current signal (SIC) and the location of the peak of premixed combustion (LPPC) in the rate of heat release trace. Based on this correlation, a PID closed loop controller is developed to adjust the injection timing for proper combustion phasing under steady and transient engine operating conditions.

Thermal barrier coatings are becoming increasingly important in providing thermal insulation for heat engine components. Thermal insulation reduces in-cylinder heat transfer from the engine combustion chamber as well as reducing component structural temperatures. Containment of heat also contributes to increased in-cylinder work and offers higher exhaust temperatures for energy recovery. Lower component structural temperatures will result in greater durability. Advanced ceramic composite coatings also offer the unique properties that can provide reductions in friction and wear. Test results and analysis to evaluate the performance benefits of thin thermal barrier coated components in a single cylinder diesel engine are presented.

Unburned hydrocarbon (UBHC) emissions from gasoline engines remain a primary engineering research and development concern due to stricter emission regulations. Gasoline engines produce more UBHC emissions during cold start and warm-up than during any other stage of operation, because of insufficient fuel-air mixing, particularly in view of the additional fuel enrichment used for early starting. Impingement of fuel droplets on the cylinder wall is a major source of UBHC and a concern for oil dilution. This paper describes an experimental study that was carried out to investigate the distribution and “footprint” of fuel droplets impinging on the cylinder wall during the intake stroke under engine starting conditions. Injectors having different targeting and atomization characteristics were used in a 4-Valve engine with optical access to the intake port and combustion chamber.

The successful design of engine components for high temperature applications is very dependent on the use of advanced finite element methods. Without the use of thermal and structural modeling techniques it is virtually impossible to establish the reliable design specifications to meet the application requirements. Advanced modeling and design of two key engine components, the cylinder head thermal insulating headface plate and the capped air gap insulated piston, are presented. Prior engine test experience contributes to further understanding of the important factors in recognizing successful design solutions. It has been found that the modeling results are only as good as the modeling assumptions and that all modeling boundary conditions and constraints must be reviewed carefully.

Concentrations of individual species in the engine-out exhaust gas from a gasoline-fueled (101.5 or 91.5 RON), direct-injection, compression-ignition (HCCI) engine have been measured by gas chromatography over the A/F range 50 to 230 for both stratified and nearly homogeneous fuel-air mixtures. The species identified include hydrocarbons, oxygenated organic species, CO, and CO2. A single-cylinder HCCI engine (CR = 15.5) with heated intake charge was used. Measurements of the mass and size distribution of particulate emissions were also performed. The 101.5 RON fuel consisted primarily of five species, simplifying interpretation of the exhaust species data: iso-pentane (24%), iso-octane (22%), toluene (17%), xylenes (10%), and trimethylbenzenes (9%).

A numerical simulation of shock wave generation by high-pressure and high-speed spray jet has been conducted to compare to the experimental results obtained by X-ray radiographic technique. Using the space-time conservation element solution element (CESE) method and the stochastic particle techniques to account for fuel injections and droplet collisions, supersonic-spray-induced shock waves are successfully simulated. Similar to the experimental condition, a non-evaporating diesel spray in a chamber filled with inert gas sulfur hexafluoride (SF6) at 1 atm pressure under room temperature (30° C) is simulated. To simulate the needle lift effect in the single-hole diesel injector, various injection-rate profiles were employed. In addition, the effects of discharge coefficients, with Cd ranging from 0.8 to 1.0, were also considered to simulate the shock generation processes in the leading spray front.