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This paper presents a virtual analysis method for pressure spike estimation and optimization of hydraulic system architecture for off-highway applications with hydraulically actuated clutch. This pressure spike leads to a very high torque spike in driveline components during clutch pop-up conditions in puddling operations. These torque spikes lead to potential failure of driveline components i.e., gear, shaft, bearing and torsional damper during sudden engagement events. To assess the hydraulic system performance during clutch pop-up cornering conditions is very challenging and leads to compromise on operator safety in the paddy field. It is essential to develop a simulation methodology in a virtual environment to understand the system behavior during clutch pop-up condition and impact of various hydraulic system parameters. This paper describes a Model Based System Design (MBSD) approach for understanding hydraulic system pressure spike phenomenon and dynamic response.

Ducted fuel injection (DFI), a concept that utilizes fuel injection through ducts, was implemented in a constant pressure High Temperature Pressure Vessel at 60 bar ambient pressure, 800-1000 K ambient temperature, and 21 % oxygen. The ducts were 14 mm long and placed 3-4.7 mm from the orifice exit. The duct diameters ranged from 1.6-3.2 mm and had a rounded inlet and a tapered outlet. Diesel fuel was used in single-orifice fuel injectors operating at 250 MPa rail pressure. The objective of this work was to study soot reduction for various combinations of orifice and duct diameters. A complete data set was taken using the 150 μm orifice. A smaller data set was acquired for a 219 μm orifice, showing similar trends. Soot reduction peaked at an optimal duct diameter of 2-2.25 mm, corresponding to an 85-90 % spray area reduction for the 150 μm orifice. Smaller or larger duct diameters were less effective. Duct diameter had a minimal effect on ignition delay.

Ducted fuel injection (DFI) has been shown to be an effective method to significantly reduce soot formation in mixing controlled compression ignition (MCCI) diesel combustion. This reduction has been demonstrated in both combustion vessels and in an optical engine. The mechanisms driving the soot reduction are to date not fully understood. Optimal duct configurations are also not immediately evident. The objective of this study is to show the effects of two geometric variables, namely distance from fuel injector orifice exit to duct inlet (0.1-6 mm) for a 2x14 mm duct, and duct length variation (8-14 mm) at a given stand-off distance of 0.1 mm. A 138 μm on-axis single-orifice injector operated at 100-250 MPa was used in a heated, continuous flow, constant pressure vessel with optical access.

Asymmetric particulate filters (PF), where the inlet channel is wider than the outlet channel, are commonly used because of their greater capacity for ash. Somewhat surprisingly, very few models for asymmetric PFs have been published and none of these gives a correct/detailed description of the geometry. For example, octahedral channels may be treated as if they were square or the tapering walls between the inlet and outlet channels treated as if they were rectangular in cross section. Alternatively, the equations may be presented in generic form in terms of channel cross-sectional areas and perimeters, but without giving any indication of how to calculate these. This paper aims to address these deficiencies with a model that correctly describes the geometry of square and octo-square asymmetric PFs. Expressions for the solid fraction of the PF (which affects thermal mass) and channel cross section and perimeter (both when clean and soot/ash loaded) are presented.

Clutches are commonly utilised in passenger type and off-road heavy-duty vehicles to disconnect the engine from the driveline and other parasitic loads. In off-road heavy-duty vehicles, along with fuel efficiency start-up functionality at extended ambient conditions, such as low temperature and intake absolute pressure are crucial. Off-road vehicle manufacturers can overcome the parasitic loads in these conditions by oversizing the engine. Caterpillar Inc. as the pioneer in off-road technology has developed a novel clutch design to allow for engine downsizing while vehicle’s performance is not affected. The tribological behaviour of the clutch will be crucial to start engagement promptly and reach the maximum clutch capacity in the shortest possible time and smoothest way in terms of dynamics. A multi-body dynamics model of the clutch system is developed in MSC ADAMS. The flywheel is introducing the same speed and torque as the engine (represents the engine input to the clutch).

Octane appetite of modern engines has changed as engine designs have evolved to meet performance, emissions, fuel economy and other demands. The octane appetite of seven modern vehicles was studied in accordance with the octane index equation OI=RON-KS, where K is an operating condition specific constant and S is the fuel sensitivity (RONMON). Engines with a displacement of 2.0L and below and different combinations of boosting, fuel injection, and compression ratios were tested using a decorrelated RONMON matrix of eight fuels. Power and acceleration performance were used to determine the K values for corresponding operating points. Previous studies have shown that vehicles manufactured up to 20 years ago mostly exhibited negative K values and the fuels with higher RON and higher sensitivity tended to perform better.

Southwest Research Institute (SwRI) has successfully demonstrated the cooled EGR concept via the High Efficiency Dilute Gasoline Engine (HEDGE) consortium. Dilution of intake charge provides three significant benefits - (1) Better Cycle Efficiency (2) Knock Resistance and (3) Lower NOx/PM Emissions. But EGR dilution also poses challenges in terms of combustion stability, condensation and power density. The Dedicated EGR (D-EGR) concept brings back some of the stability lost due to EGR dilution by introducing reformates such as CO and H2 into the intake charge. Control of air, EGR, fuel, and ignition remains a challenge to realizing the aforementioned benefits without sacrificing performance and drivability. This paper addresses the DEGR solution from a controls standpoint. SwRI has been developing a unified framework for controlling a generic combustion engine (gasoline, diesel, dual-fuel natural gas etc.).

Despite numerous research efforts, there is no reliable and widely accepted tool for the prediction of erosion prone material surfaces due to collapse of cavitation bubbles. In the present paper an Erosion Aggressiveness Index (EAI) is proposed, based on the pressure loads which develop on the material surface and the material yield stress. EAI depends on parameters of the liquid quality and includes the fourth power of the maximum bubble radius and the bubble size number density distribution. Both the newly proposed EAI and the Cavitation Aggressiveness Index (CAI), which has been previously proposed by the authors based on the total derivative of pressure at locations of bubble collapse (DP/Dt>0, Dα/Dt<0), are computed for a cavitating flow orifice, for which experimental and numerical results on material erosion have been published. The predicted surface area prone to cavitation damage, as shown by the CAI and EAI indexes, is correlated with the experiments.

The presented work describes how spark calorimeter testing was used for parametric study and secondary circuit model calibration. Tests were conducted at different pressures, sparkplug gaps and supplied primary energies. The conversion efficiency increases and the spark duration decreases when the gas pressure or the sparkplug gap size is increased. Both gas pressure and sparkplug gas size increase the positive column voltage which represents part of the electrical energy delivered to the gas. The opposite direction occurs when the supplied primary energy is increased. The testing results were then used to calibrate the secondary circuit model which consisted of the sparkplug, the sparkplug gap and the secondary wiring. A step-by-step method was used to calibrate the three constants of the model to match the calculated delivered energy with test data during arc / glow phase.

Enhancement of fuel/air mixing is one path towards enabling future diesel engines to increase efficiency and control emissions. Air-assist fuel injections have shown potential for low pressure applications and the current work aims to extend air-assist feasibility understanding to high pressure environments. Analyses were completed and carried out for traditional high pressure fuel-only, internal air-assist, and external air-assist fuel/air mixing processes. A combination of analytical 0-D theory and 3D CFD were used to help understand the processes and guide the design of the air-assisted setup. The internal air-assisted setup was determined to have excellent liquid fuel vaporization, but poorer fuel dispersion than the traditional high-pressure fuel injections.

The dual-fuel combustion process of ethanol and n-heptane was characterized experimentally in an optically accessible engine and numerically through a chemical kinetic 3D-CFD investigation. Previously reported formaldehyde PLIF distributions were used as a tracer of low-temperature oxidation of straight-chained hydrocarbons and the numerical results were observed to be in agreement with the experimental data. The numerical and experimental evidence suggests that a change in the speed of flame propagation is responsible for the observed behavior of the dual-fuel combustion, where the energy release duration is increased and the maximum rate of pressure rise is decreased. Further, an explanation is provided for the asymmetrical energy release profile reported in literature which has been previously attributed to an increase in the diffusion-controlled combustion phase.

Diesel injection equipment is required to be more accurate and higher in pressure to meet the increasingly strict emission, fuel consumption regulations and higher engine performance. It also needs to achieve a number of requirements such as robustness against diversified market fuels, easy installation to engine, etc.

This paper summarizes the Heavy-Duty In-Use Testing (HDUIT) measurement allowance program for Particulate Matter Portable Emissions Measurement Systems (PM-PEMS). The measurement allowance program was designed to determine the incremental error between PM measurements using the laboratory constant volume sampler (CVS) filter method and in-use testing with a PEMS. Two independent PM-PEMS that included the Sensors Portable Particulate Measuring Device (PPMD) and the Horiba Transient Particulate Matter (TRPM) were used in this program. An additional instrument that included the AVL Micro Soot Sensor (MSS) was used in conjunction with the Sensors PPMD to be considered a PM-PEMS. A series of steady state and transient tests were performed in a 40 CFR Part 1065 compliant engine dynamometer test cell using a 2007 on-highway heavy-duty diesel engine to quantify the accuracy and precision of the PEMS in comparison with the CVS filter-based method.

In recent decades, “physics-based” gas-dynamics simulation tools have been employed to reduce development timescales of IC engines by enabling engineers to carry out parametric examinations and optimisation of alternative engine geometry and operating strategy configurations using desktop PCs. However to date, these models have proved inadequate for optimisation of in-cylinder combustion and emissions characteristics thus extending development timescales through additional experimental development efforts. This research paper describes how a Stochastic Reactor Model (SRM) with reduced chemistry can be employed to successfully determine in-cylinder pressure, heat release and emissions trends from a diesel fuelled engine operated in compression ignition direct injection mode using computations which are completed in 147 seconds per cycle.

Total and solid particle mass, size, and number were measured in the dilute exhaust of a 2009 vehicle equipped with a gasoline direct injection engine along with an exhaust three-way-catalyst. The measurements were performed over the FTP-75 and the US06 drive cycles using three different U.S. commercially available fuels, Fuels A, B, and C, where Fuel B was the most volatile and Fuel C was the least volatile with higher fractions of low vapor pressure hydrocarbons (C10 to C12), compared to the other two fuels. Substantial differences in particle mass and number emission levels were observed among the different fuels tested. The more volatile gasoline fuel, Fuel B, resulted in the lowest total (solid plus volatile) and solid particle mass and number emissions. This fuel resulted in a 62 percent reduction in solid particle number and an 88 percent reduction in soot mass during the highest emitting cold-start phase, Phasel, of the FTP-75, compared to Fuel C.

In-cylinder emission controls were the focus for diesel engines for many decades before the emergence of diesel aftertreatment. Even with modern aftertreatment, control of in-cylinder processes remains a key issue for developing diesel vehicles with low tailpipe emissions. A reduction in in-cylinder emissions makes aftertreatment more effective at lower cost with superior fuel economy. This paper describes a study focused on an in-cylinder combustion control approach using a Delphi E3 flexible fuel system to achieve low engine-out NOx and PM emissions. A 2003 model year Detroit Diesel Corporation Series 60 14L heady-duty diesel engine, modified to accept the Delphi E3 unit injectors, and ultra low sulfur fuel were used throughout this study. The process of achieving premixed low temperature combustion within the limited range of parameters of the stock ECU was investigated.

A gasoline direct injection engine was operated at elevated EGR levels over a significant portion of the performance map. The engine was modified to use both cooled and un-cooled EGR in high pressure loop and low pressure loop configurations. The addition of EGR at low and part load was shown to decrease NO and CO emissions and to reduce fuel consumption by up to 4%, primarily through the reduction in pumping losses. At high loads, the addition of EGR resulted in higher fuel consumption benefits of 10-20% as well as the expected NO and CO reductions. The fuel economy benefit at high loads resulted from a decrease in knock tendency and a subsequent improvement in combustion phasing as well as reductions in exhaust temperatures that eliminated the requirement for over-fuelling.

SwRI has developed a new technology concept involving the use of high EGR rates coupled with a high-energy ignition system in a gasoline engine to improve fuel economy and emissions. Based on a single-cylinder study [1], this study extends the concept of a high compression ratio gasoline engine with EGR rates > 30% and a high-energy ignition system to a multi-cylinder engine. A 2000 MY Isuzu Duramax 6.6 L 8-cylinder engine was converted to run on gasoline with a diesel pilot ignition system. The engine was run at two compression ratios, 17.5:1 and 12.5:1 and with two different EGR systems - a low-pressure loop and a high pressure loop. A high cetane number (CN) diesel fuel (CN=76) was used as the ignition source and two different octane number (ON) gasolines were investigated - a pump grade 91 ON ((R+M)/2) and a 103 ON ((R+M)/2) racing fuel.

A fire exposure test was conducted on a 72.4 liter composite (Type HGV-4) hydrogen fuel tank at an initial hydrogen pressure of 34.3 MPa (ca 5000 psi). No Pressure Relief Device was installed on the tank to ensure catastrophic failure for analysis. The cylinder ruptured at 35.7 MPa after a 370 kW fire exposure for 6 min 27 seconds. Blast wave pressures measured along a line perpendicular to the cylinder axis were 18% to 25% less the values calculated from ideal blast wave correlations using a blast energy of 13.4 MJ, which is based on the ideal gas internal energy at the 35.7 MPa burst pressure. The resulting hydrogen fireball maximum diameter of 7.7 m is about 19% less than the value predicted from existing correlations using the 1.64 kg hydrogen mass in the tank.

Tremendous amount of useful information can be extracted from the cylinder pressure signal for engine combustion control. However, the physical cylinder pressure sensors are undesirably expensive and their health need to be monitored for fault diagnostic purpose as well. This paper presents the results of the development of a virtual cylinder pressure sensor (VCPS) with individual variable-oriented independent estimators. Two neural network-based independent cylinder pressure related variable estimators were developed and verified at steady state. The results show that these models can predict the variables correctly compared with the extracted variables from the measured physical cylinder pressure sensor signal. Good generalization capabilities of the developed models are observed in the sense that the models work well not only for the training data set but also for the new inputs that they have never been exposed to before.