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Under the borderline autoignition conditions experienced during cold-starting of diesel engines, the amount and composition of residual gases may play a deterministic role. Among the intermediate species produced by misfiring and partially firing cycles, formaldehyde (HCHO) is produced in significant enough amounts and is sufficiently stable to persist through the exhaust and intake strokes to kinetically affect autoignition of the following engine cycle. In this work, the effect of HCHO addition at various phases of autoignition of n-heptane-air mixtures is kinetically modeled. Results show that HCHO has a retarding effect on the earliest low-temperature heat release (LTHR) phase, largely by competition for hydroxyl (OH) radicals which inhibits fuel decomposition. Conversely, post-LTHR, the presence of HCHO accelerates the occurrence of high-temperature ignition.

Automated driving functionalities delivered through Advanced Driver Assistance System (ADAS) have been adopted more and more frequently in consumer vehicles. The development and implementation of such functionalities pose new challenges in safety and functional testing and the associated validations, due primarily to their high demands on facility and infrastructure. This paper presents a rather unique Vehicle-in-the-Loop (VIL) test setup and methodology compared those previously reported, by combining the advantages of the hardware-in-the-loop (HIL) and traditional chassis dynamometer test cell in place of on-road testing, with a multi-agent real-time simulator for the rest of test environment.

Fast and accurate characterization of stability regions and operational range with respect to pull-in voltage and displacement is critical in the design and development of MEMS resonators and switches. This paper presents a mathematical and computational procedure for modeling and analysis of static and dynamic instabilities of capacitive microdevices employing resonant microbeams. The mathematical model consists of a nonlinear microbeam under distributed electrostatic actuation and squeeze film damping. The coupled system is described by the nonlinear beam equation and a modified compressible Reynolds equation to account for the rarefied gas in the narrow gap between the microbeam and substrate. The Differential Quadrature Method (DQM) is used to discretize partial differential equations of motion and solve for static deflection, natural frequencies, static pull-in voltage, and quality factors for various encapsulation air pressures and applied DC voltages.

Misfiring or partial combustion during diesel engine operation results in the production of partial oxidation products such as ethylene (C₂H₄), carbon monoxide and aldehydes, in particular formaldehyde (HCHO). These compounds remain in the cylinder as residual gases to participate in the following engine cycle. Carbon monoxide and formaldehyde have been shown to exhibit a dual nature, retarding ignition in one temperature regime, yet decreasing ignition delay periods of hydrocarbon mixtures as temperatures exceed 1000°K. Largely unknown is the synergistic effects of such species. In this work, varying amounts of C₂H₄ and HCHO are added to the intake air of a naturally aspirated optical diesel engine and their combined effect on autoignition and subsequent combustion is examined. To observe the effect of these dopants on the low-temperature heat release (LTHR), ultraviolet chemiluminescent images are recorded using intensified CCD cameras.

Up to now, there is no standard methodology that addresses how driver distraction is affected by perceptual demand and working memory demand - aside from visual allocation. In 2009, the Peripheral Detection Task (PDT) became a NHTSA recommended measure for driver distraction [1]. Then the PDT task was renamed as the Detection Response Task (DRT) because the International Standards Organization (ISO) has identified this task as a potential method for assessing selective attention in detection of visual, auditory, tactile and haptic events while driving. The DRT is also under consideration for adoption as an ISO standard surrogate test for driver performance for new telematics designs. The Wayne State University (WSU) driver imaging group [2, 3] improved the PDT and created the Enhanced Peripheral Detection Task I (EPDT-I) [4]. The EPDT-I is composed of a simple visual event detection task and a video of a real-world driving scene.

An iterative learning control (ILC) algorithm has been developed for a test cell electro-hydraulic, fully flexible valve actuation system to track valve lift profile under steady-state and transient operation. A dynamic model of the plant was obtained from experimental data to design and verify the ILC algorithm. The ILC is implemented in a prototype controller. The learned control input for two different lift profiles can be used for engine transient tests. Simulation and bench test are conducted to verify the effectiveness and robustness of this approach. The simple structure of the ILC in implementation and low cost in computation are other crucial factors to recommend the ILC. It does not totally depend on the system model during the design procedure. Therefore, it has relatively higher robustness to perturbation and modeling errors than other control methods for repetitive tasks.

Due to the single fuel concept implemented by the US military, the soot production of diesel engines fueled with JP-8 has important implications for military vehicle visual signature and survivability. This work compares in-cylinder soot formation and oxidation of JP-8 and ULSD in a small-bore, optical diesel engine. Experimental engine-out soot emission measurements are compared to crank-angle resolved two-color measurements of soot temperature and optical thickness, KL. A 3-D chemical kinetic-coupled CFD model with line of sight integration is employed in order to investigate the soot distribution in a 2-D projection associated with the imaging plane, as well as to aid in interpreting the third dimension along the optical depth which is not available within the experimental work. The study also examines the effect of volatility on soot emission characteristics by CFD simulation.

This study evaluates the performance of an indirect injection (IDI) diesel engine fueled with cotton seed biodiesel while assessing the engine's multi-fuel capability. Millions of tons of cotton seeds are available in the south of the US every year and approximately 10% of oil contained in the seeds can be extracted and transesterified. An investigation of combustion, emissions, and efficiency was performed using mass ratios of 20-50% cotton seed biodiesel (CS20 and CS50) in ultra-low sulfur diesel #2 (ULSD#2). Each investigation was run at 2400 rpm with loads of 4.2 - 6.3 IMEP and compared to the reference fuel ULDS#2. The ignition delay ranged in a narrow interval of 0.8-0.97ms across the blends and the heat release rate showed comparable values and trends for all fuel blends. The maximum volume averaged cylinder temperature increased by approximately 100K with each increase in 1 bar IMEP load but the maximum remained constants across the blends.

Several mechanisms are discussed to understand the particulate matter (PM) characterization in a high speed, direct injection, single cylinder diesel engine using low sulfur diesel fuel. This includes their formation, size distribution and number density. Experiments were conducted over a wide range of injection pressures, EGR rates, injection timings and swirl ratios, therefore covering both conventional and low temperature combustion regimes. A micro dilution tunnel was used to immediately dilute a small part of the exhaust gases by hot air. A Scanning Mobility Particle Sizer (SMPS) was used to measure the particulate size distribution and number density. Particulate mass was measured with a Tapered Element Oscillating Microbalance (TEOM). Analysis was made of the root cause of PM characterization and their relationship with the combustion process under different operating conditions.

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.

The short NiTi fiber-reinforced NiTi/Al6061-SiC composite was recently developed through the U.S. Army SBIR Phase-II program [1]. The objectives of this project are to use short NiTi fiber reinforcement to induce compressive stress through shape memory effect, to use silicon carbide (SiC) particulate reinforcement to enhance the mechanical properties of the aluminum matrix, to gain fundamental knowledge of short NiTi fiber-reinforced aluminum matrix composite, and eventually to improve fatigue resistance, impact damage tolerance and fracture toughness of the composite. The fatigue life, damage and fracture behavior of TiNi/Al6061-SiC, TiNi/Al6061, Al6061-SiC composites as well as monolithic Al6061 alloy were investigated under fully reversed cyclic loading. It was found that fatigue life of NiTi/Al6061-SiC composite, in term of the cycles, increased by two orders of magnitude, compared to monolithic Al6061 alloy

This paper presents an experimental investigation conducted to determine the parameters that control the behavior of autoignition in a small-bore, single-cylinder, optically-accessible diesel engine. Depending on operating conditions, three types of autoignition are observed: a single ignition, a two-stage process where a low temperature heat release (LTHR) or cool flame precedes the main premixed combustion, and a two-stage process where the LTHR or cool flame is separated from the main heat release by an apparent negative temperature coefficient (NTC) region. Experiments were conducted using commercial grade low-sulfur diesel fuel with a common-rail injection system. An intensified CCD camera was used for ultraviolet imaging and spectroscopy of chemiluminescent autoignition reactions under various operating conditions including fuel injection pressures, engine temperatures and equivalence ratios.

The focus of this study is to determine the effect of using B-20 (a blend of 20% soybean methyl ester biodiesel and 80% ultra low sulfur diesel fuel) on the combustion process, performance and exhaust emissions in a High Speed Direct Injection (HSDI) diesel engine equipped with a common rail injection system. The engine was operated under simulated turbocharged conditions with 3-bar indicated mean effective pressure and 1500 rpm engine speed. The experiments covered a wide range of injection pressures and EGR rates. The rate of heat release trace has been analyzed in details to determine the effect of the properties of biodiesel on auto ignition and combustion processes and their impact on engine out emissions. The results and the conclusions are supported by a statistical analysis of data that provides a quantitative significance of the effects of the two fuels on engine out emissions.

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 effects of different blends of Soybean Methyl Ester (biodiesel) and ultra low sulfur diesel (ULSD) fuel: B-00 (ULSD), B-20, B-40, B-60, B-80 and B-100 (biodiesel); on autoignition, combustion, performance, and engine out emissions of different species including particulate matter (PM) in the exhaust, were investigated in a single-cylinder, high speed direct injection (HSDI) diesel engine equipped with a common rail injection system. The engine was operated at 1500 rpm under simulated turbocharged conditions at 5 bar IMEP load with varied injection pressures at a medium swirl of 3.77 w ithout EGR. Analysis of test results was done to determine the role of biodiesel percentage in the fuel blend on the basic thermodynamic and combustion processes under fuel injection pressures ranging from 600 bar to 1200 bar.

Experimental data is used in conjunction with multi-dimensional modeling in a modified version of the KIVA-3V code to characterize the emissions behavior of a high-speed, direct-injection diesel engine. Injection pressure and EGR are varied across a range of typical small-bore diesel operating conditions and the resulting soot-NOx tradeoff is analyzed. Good agreement is obtained between experimental and modeling trends; the HSDI engine shows increasing soot and decreasing NOx with higher EGR and lower injection pressure. The model also indicates that most of the NOx is formed in the region where the bulk of the initial heat release first takes place, both for zero and high EGR cases. The mechanism of NOx reduction with high EGR is shown to be primarily through a decrease in thermal NOx formation rate.

This paper investigates the use of an adaptive proportional-integral-derivative (APID) controller to reduce a combustion engine crankshaft speed pulsation. Both computer simulations and engine test rig experiments are used to validate the proposed control scheme. The starter/alternator (S/A) is used as the actuator for engine speed control. The S/A is an induction machine. It produces a supplemental torque source to cancel out the fast engine torque variation. This machine is placed on the engine crankshaft. The impact of the slowly varying changes in engine operating conditions is accounted for by adjusting the APID controller parameters on-line. The APID control scheme tunes the PID controller parameters by using the theory of adaptive interaction. The tuning algorithm determines a set of PID parameters by minimizing an error function. The error function is a weighted combination of the plant states and the required control effort.

The emissions trade-off and combustion characteristics of a high speed, small-bore, direct injection, single cylinder, diesel engine are investigated at three different load conditions. The experiments covered a wide range of parameters including the injection pressure, exhaust gas recirculation (EGR) rate and swirl ratio (Sw). The effects of each parameter on the ignition delay (ID), apparent rate of energy release (ARER), NOx, Bosch smoke unit (BSU), CO and hydrocarbons are investigated. The results show that the NOx emission dropped continuously with the increase in EGR (up to 55%), but with increasing smoke emission in a classical trade-off relationship. The increase in injection pressure generally reduced smoke with NOx penalty; however, the NOx penalty decreased at higher EGR. There also appears to be an increase in the cool flame intensity at the high EGR rates. Applying swirl at high EGR rate and high injection pressure conditions further reduced smoke emissions.

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.

Experiments were conducted to investigate the characteristics of a common rail fuel injection system using a flow rate test rig and a single cylinder research diesel engine. Experiments covered speeds and loads typical to engine conditions under Hybrid Electric Vehicle operation. Different injection modes were investigated including main injection, main-post injection and pilot-main injection. The analysis indicated that the common rail fuel pressure affects all the injection parameters including the start of fuel delivery, its duration and amount under all modes of injection. Also, the pressure waves produced in the system have an impact on the operation of the nozzle-needle and fuel delivery particularly in the main-post injection mode.