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This paper reports on a comprehensive, crank-angle transient, three dimensional, computational fluid dynamics (CFD) model of the complete lubrication system of a multi-cylinder engine using the CFD software Simerics-Sys / PumpLinx. This work represents an advance in system-level modeling of the engine lubrication system over the current state of the art of one-dimensional models. The model was applied to a 16 cylinder, reciprocating internal combustion engine lubrication system. The computational domain includes the positive displacement gear pump, the pressure regulation valve, bearings, piston pins, piston cooling jets, the oil cooler, the oil filter etc… The motion of the regulation valve was predicted by strongly coupling a rigorous force balance on the valve to the flow.

The effects of thermal and chemical aging on the performance of cordierite-based and high-porosity mullite-based diesel particulate filters (DPFs), were quantified, particularly their filtration efficiency, pressure drop, and regeneration capability. Both catalyzed and uncatalyzed core-size samples were tested in the lab using a diesel fuel burner and a chemical reactor. The diesel fuel burner generated carbonaceous particulate matter with a pre-specified particle-size distribution, which was loaded in the DPF cores. As the particulate loading evolved, measurements were made for the filtration efficiency and pressure drop across the filter using, respectively, a Scanning Mobility Particle Sizer (SMPS) and a pressure transducer. In a subsequent process and on a different bench system, the regeneration capability was tested by measuring the concentration of CO plus CO2 evolved during the controlled oxidation of the carbonaceous species previously deposited on the DPF samples.

Thermal efficiencies of 54% have been demonstrated by single cylinder engine testing of advanced diesel engine concepts developed under Department of Energy funding. In order for these concept engines to be commercially viable, cost effective and durable systems for insulating the piston, head, ports and exhaust manifolds will be required. The application and development of new materials such as thick thermal barrier coating systems will be key to insulating these components. Development of test methods to rapidly evaluate the durability of coating systems without expensive engine testing is a major objective of current work. In addition, a novel, low cost method for producing thermal barrier coated pistons without final machining of the coating has been developed.

Although soot-formation processes in diesel engines have been well characterized during the mixing-controlled burn, little is known about the distribution of soot throughout the combustion chamber after the end of appreciable heat release during the expansion and exhaust strokes. Hence, the laser-induced incandescence (LII) diagnostic was developed to visualize the distribution of soot within an optically accessible single-cylinder direct-injection diesel engine during this period. The developed LII diagnostic is semi-quantitative; i.e., if certain conditions (listed in the Appendix) are true, it accurately captures spatial and temporal trends in the in-cylinder soot field. The diagnostic features a vertically oriented and vertically propagating laser sheet that can be translated across the combustion chamber, where “vertical” refers to a direction parallel to the axis of the cylinder bore.

Nitrites have long been added to heavy-duty coolant to inhibit iron cylinder liner corrosion initiated by cavitation. However, in heavy-duty use, nitrites deplete from the coolant, which then must be refortified using supplemental coolant additives (SCA's). Recently, carboxylates have also been found to provide excellent cylinder liner protection in heavy-duty application. Unlike nitrites, carboxylate inhibitors deplete slowly and thus do not require continual refortification with SCA's. In the present paper laboratory aging experiments shed light on the mechanism of cylinder liner protection by these inhibitors. The performance of carboxylates, nitrites and mixtures of the two inhibitors are compared. Results correlate well with previously published fleet data. Specifically, rapid nitrite and slow carboxylate depletion are observed. More importantly, when nitrite and carboxylates are used in combination, nitrite depletion is repressed while carboxylates deplete at a very slow rate.

Fuel properties impact the engine-out emission directly. For some geographic regions where diesel engines can meet emission regulations without aftertreatment, the change of fuel properties will lead to final tailpipe emission variation. Aftertreatment systems such as Diesel Particulate Filter (DPF) and Selective Catalytic Reduction (SCR) are required for diesel engines to meet stringent regulations. These regulations include off-road Tier 4 Final emission regulations in the USA or the corresponding Stage IV emission regulations in Europe. As an engine with an aftertreatment system, the change of fuel properties will also affect the system conversion efficiency and regeneration cycle. Previous research works focus on prediction of engine-out emission, and many are based on chemical reactions. Due to the complex mixing, pyrolysis and reaction process in heterogeneous combustion, it is not cost-effective to find a general model to predict emission shifting due to fuel variation.

Catalytic converters have become a viable aftertreatment system for reducing emissions from on-highway diesel engines. This paper addresses the development and production qualification of a catalytic converter. The testing programs that were utilized to qualify the converter system for production included emissions performance, emissions durability, physical durability, and field test programs. This paper reports on the specific tests that were utilized for the emissions performance and emissions durability testing programs. An explanation on the development of an accelerated durability test program is also included. The physical durability section of the paper discusses the development and execution of laboratory bench tests to insure the catalytic converter/muffler maintains acceptable physical integrity.

A slipstream of exhaust from a Caterpillar 3126B engine was diverted into a plasma-catalytic NOx control system in the space velocity range of 7,000 to 100,000 hr-1. The stream was first fed through a non-thermal plasma that was formed in a coaxial cylinder dielectric barrier discharge reactor. Plasma treated gas was then passed over a catalyst bed held at constant temperature in the range of 573 to 773 K. Catalysts examined consisted of γ-alumina, indium-doped γ-alumina, and silver-doped γ-alumina. Road and rated load conditions resulted in engine out NOx levels of 250 - 600 ppm. The effects of hydrocarbon level, catalyst temperature, and space velocity are discussed where propene and in one case ultra-low sulfur diesel fuel (late cycle injection) were the reducing agents used for NOx reduction. Results showed NOx reduction in the range of 25 - 97% depending on engine operating conditions and management of the catalyst and slipstream conditions.

NOx reduction efficiency in simulated lean exhaust conditions has been examined for three proprietary catalyst materials using a non-thermal plasma discharge as a pretreatment stage to the catalyst. Using propene as the reducing agent for selective catalytic reduction, 74% reduction of NOx has been observed in the presence of 20 ppm SO2. For sulfur-free simulated exhaust, 84% NOx reduction has been obtained. Results show that the impact of sulfur on the samples examined can vary widely from virtually no effect (< 5%) to more than 20% loss in activity depending on the catalyst. Any loss due to sulfur poisoning appears to be irreversible according to limited measurements on poisoned catalysts exposed to sulfur-free exhaust streams. Catalysts were tested over a temperature range of 473-773K, with the highest activity observed at 773K. Examination of this large temperature window has shown that the optimum C1:NOx ratio changes with temperature.

Coolant formulations based on organic acid corrosion inhibitor technology have been tested in over 180 heavy duty engines for a total of more than 50 million kilometers. This testing has been used to document long life coolant performance in various engine types from four major engine manufacturers. Inspections of engines using organic acid based coolant (with no supplemental coolant additive) for up to 610,000 kilometers showed excellent protection of metal engine components. Improved protection was observed against cylinder liner, water pump, and aluminum spacer deck corrosion. In addition, data accumulated from this testing were used to develop depletion rate curves for long life coolant corrosion inhibitors, including tolyltriazole and nitrite. Nitrite was observed to deplete less rapidly in long life coolants than in conventional formulations.

The design of a pressure compensated hydraulic valve is optimized using CFD analysis. The valve is used in a hydraulic system to control implement movement. High flow rates through the valve resulted in unacceptably high pressure drops, leading to an effort to optimize the valve design. Redesign of the valve had to be achieved under the constraint of minimal manufacturing cost. The flow path of hydraulic oil through the valve, the spool design, and various components of the valve that caused the high pressure drops were targeted in this analysis. A commercially available CFD package was used for the 3D analysis. The hydraulic oil flow was assumed to be turbulent, isothermal and incompressible. The steady-state results were validated by comparison with experimental data.

Studies of transient diesel spray characteristics at high injection pressures were conducted in a constant volume chamber by utilizing a high speed photography and light extinction optical diagnostic technique. Two different types of nozzle hole entrances were investigated: a sharp-edged and a round-edged nozzle. The experimental results show that for the same injection delivery, the sharp-edged inlet injector needed a higher injection pressure to overcome the higher friction loss, but it produced longer spray tip penetration length, larger spray angle, smaller droplet sizes, and also lower particulate emission from a parallel engine test. For the round-edged and smooth edged tips at the same injection pressure, the sharp-edged inlet tip took a longer injection duration to deliver a fixed mass of fuel and produced larger overall average Sauter Mean Diameter (SMD) droplets.

A nonlinear, three-dimensional finite element analysis of the cylinder head gasket joint has been developed to allow accurate prediction of global and local joint behavior during engine operation. Nonlinear material properties and load cases that simulate full cycle engine operation are the analysis foundation. The three-dimensional, nonlinear, full-cycle simulation accurately predicts cylinder head gasket joint response to assembly, thermal, and cylinder pressure loading. Predictions correlate well with measured engine test data. Analysis results include local pressure distribution and global load splits. Insight into joint loading and an improved understanding of overall joint behavior provide the basis for informed design and development decisions.

With stringent emission regulations, aftertreatment systems with a Diesel Particulate Filter (DPF) and a Selective Catalytic Reduction (SCR) are required for diesel engines to meet PM and NOx emissions. The adoption of aftertreatment increases the back pressure on a typical diesel engine and makes engine calibration a complicated process, requiring thousands of steady state testing points to optimize engine performance. When configuring an engine to meet Tier IV final emission regulations in the USA or corresponding Stage IV emission regulations in Europe, this high back pressure dramatically impacts transient performance. The peak NOx, smoke and exhaust temperature during a diesel engine transient cycle, such as the Non-Road Transient Cycle (NRTC) defined by the US Environmental Protection Agency (EPA), will in turn affect the performance of the aftertreatment system and the tailpipe emissions level.

Since the advent of P/M technology as a near net shape production process, millions of mechanical components of various shapes and sizes have been produced. Although P/M continues to be one of the fast growing shaping processes, it suffers from the inability to produce intricate geometry's such as internal tapers, threads or recesses perpendicular to pressing direction. In such cases application of machining as a secondary forming operation becomes the preferred alternative. However, machining of P/M parts due to their inherent porosity is known to decrease tool life and increase tool chatter and vibration. Consequently, several attempts have been made to improve the machinability of P/M materials by either addition of machinability enhancing elements such as sulfur, calcium, tellurium, selenium, etc., or by resin impregnation of P/M parts.

This paper details results of a numerical and experimental investigation into the relative performance of vaned and vaneless mixed flow turbines for application to medium and heavy-duty diesel engines utilizing pulse exhaust systems. Previous investigations into the impact of nozzle vanes on turbine performance considered only open turbine housings, whereas a majority of medium and heavy-duty diesel engine applications are six-cylinder engines using pulse exhaust systems with divided turbines. The two turbine stages for this investigation were carefully designed to meet the constraints of engines with pulse exhaust systems and to control confounding factors that would undermine the vaned vs vaneless performance comparison. Detailed CFD analysis and turbine dynamometer test results confirm a significant efficiency advantage for the vaned turbine stage under both full and partial admission conditions.

Past experiments have shown that numerous micro-hole sprays in close proximity produce drop sizes that are sensitive to the nozzle arrangement. Numerical studies have been performed to identify the interaction mechanisms between closely spaced sprays. It is shown that nozzle configurations can lower the drop-gas relative velocity and droplet Weber number, leading to reduced atomization intensity. However, the collisions involving droplets from neighboring sprays have a much greater effect on droplet size. Thus, neighboring sprays primarily interfere with each other through droplet collision.

An improved method for studying mixing-controlled compression ignition (MCCI) flame interactions with an engine combustion chamber has been developed. It is implemented in a constant pressure vessel, which contains a portion of a piston and a portion of a cylinder head, where the cylinder head is emulated by a transparent fused silica window. This method allows for vaporizing or combusting fuel jets to be imaged from two orthogonal directions. The piston and cylinder head can be adjusted to emulate in-engine piston positions from top dead center (TDC) to approximately 15 mm away from TDC. The design allows for pistons from engine bore sizes up to approximately 175 mm to be studied, including the ability to simulate injector spray included angles from 120°-180°. In this study, the piston was made as an extruded piston bowl profile, where the length of the extrusion approximated the arc length between two neighboring jets from a 6-hole injector.

It is estimated that operating continuously on a B20 fuel containing the current allowable ASTM specification limits for metal impurities in biodiesel could result in a doubling of ash exposure relative to lube-oil-derived ash. The purpose of this study was to determine if a fuel containing metals at the ASTM limits could cause adverse impacts on the performance and durability of diesel emission control systems. An accelerated durability test method was developed to determine the potential impact of these biodiesel impurities. The test program included engine testing with multiple DPF substrate types as well as DOC and SCR catalysts. The results showed no significant degradation in the thermo-mechanical properties of cordierite, aluminum titanate, or silicon carbide DPFs after exposure to 150,000 mile equivalent biodiesel ash and thermal aging. However, exposure of a cordierite DPF to 435,000 mile equivalent aging resulted in a 69% decrease in the thermal shock resistance parameter.

Technical groups worldwide have been actively developing specifications and requirements for biodegradable hydraulic fluids for mobile applications. These groups have recognized that an industry-wide specification is necessary due to the increase in environmental awareness in the agriculture, construction, forestry, and mining industries, and to the increasing number of local regulations primarily throughout Europe. Caterpillar has responded to this need by publishing a requirement, Caterpillar BF-1, that may be used by Caterpillar dealers, customers, and industry to help select high-performance biodegradable hydraulic fluids. This requirement was written with the input of several organizations that are known to be involved with the development of similar types of specifications and requirements.