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An experimental study was conducted to investigate the effect of EGR on combustion and exhaust emissions characteristics of a spark-ignited, super-charged, stoichiometric gas engine in order to achieve high BMEP equivalent to that of diesel engines. A four-stroke-cycle single-cylinder test engine was used. EGR was completely mixed with intake air before being introduced into the compressor. The results indicate that dry EGR utilizing drained exhaust gas improved the maximum mean effective pressure, as well as specific fuel consumption over the whole load due to improved knock characteristics of the unburnt mixture, increased specific heat ratio (κ), and reduced heat loss. Further experiments were conducted to identify the effect of humidity in the mixture on engine performance. The lean burn method was compared with the EGR method.

Dual-fuel pilot ignited natural gas engines have several intrinsic advantages relative to spark ignited; mainly higher thermal efficiency and lower conversion costs. The major drawback is associated with light loads. This paper discusses objectives, approaches, methods and results of the development of strategies which overcome the drawbacks and enhance the advantages. Development of a pilot fuel injection system, having a delivery of only 1 mm3 at a duration of 0.6 ms, was described in a previous paper. This paper concentrates on the results of strategies to reduce unburned methane in the exhaust and to increase the substitution of gas at light loads through skip-fire, by-passing boost air and exhaust gas recirculation techniques. Engine tests proved that with these strategies, diesel fuel replacement of more than 95% over the entire engine operating map, including idle, can be achieved and current and anticipated future emission standards satisfied.

A pressure accumulative injection rate controllable unit injector-PAIRCUI is proposed and developed. This unit injector is powered by fuel pressure accumulation controlled by an electronic control unit and its injection rate is shaped by inner valves of the injector. Inherent advantages of an accumulator type unit injector have been carried out in this new design, including sructural simplicity, totally flexible injection timing, medium common rail pressure, tolerable pump size and flow requirement. A number of decisive features have also been realized that are significant for high efficiency and low emissions of engine combustion, including higher mean effective injection pressure(MEIP), pilot injection capability and rapid end of injection. The injection pressure is independent of engine speed, but regulated upon engine load. These characteristics are beneficial in improving engine performance and fuel consumption.

The methyl esters of soybean oil, known as biodiesel, are receiving increasing attention as renewable fuels for diesel engines. Biodiesel has a high cetane number, and offers the potential of emission reduction. The properties of biodiesel vary depending on its composition, and this may affect engine performance and emissions. In this project, biodiesel fuels were prepared from feedstocks with modified compositions including the methyl esters of a low palmitic soybean oil, a partially transesterified soybean oil, a synthetic blend of saturated esters, and a commonly used methyl soyate. These esters were blended with No. 2 diesel fuel in 20% and 50% concentrations. The blended fuels were then tested in a diesel engine to investigate the effect of biodiesel composition on performance, combustion characteristics, and emissions.

Documented herein are the methods utilized to meet the performance requirements for operation in RVSM airspace. The test aircraft was equipped with an instrumented static system and a trailing cone static reference. The trailing cone was calibrated in-flight using laser range and radio altitude tower fly-by methods. Determination of the static source error and development of the static source error correction was accomplished on the instrumented aircraft. Verification of RVSM performance was accomplished on a standard production aircraft utilizing the instrumented aircraft as a pace. Additionally, test data were also obtained with perturbations on the skin near the static ports. The measured pressure changes were correlated with computational predictions. These data were used to develop skin waviness tolerances for the area around the static ports.

A personal computer based preliminary structural design system has been developed for general aviation aircraft. Structural design is coupled with other elements of the preliminary design process to provide a unique and powerful framework for the preliminary design process. Capabilities include structural layout, structural weight sizing and detailed stress analysis. All of these can be applied to a number of built-in (and user defined) structural configurations. The program is designed to reduce preliminary design time and produce an efficient well-documented structural design that complies with regulatory specifications.

Recent studies suggest that the use of ethers as fuels or fuel additives may be a key to the simultaneous reduction of both particulate and NOx emissions from Diesel engines. The present study is directed towards understanding the chemical kinetics of autoignition of ethers under Diesel-like conditions. Autoignition experiments were performed in a constant volume apparatus (CVA), that allowed independent control of temperature, pressure, and oxidizing gas composition. Hollow cone sprays of methanol, dimethyl ether (DME), CH3OCH3, and dimethoxy methane (DMM), CH3OCH2OCH3, were created in quiescent air with a standard Diesel injector, and autoignition delays were inferred from pressure-time histories. A detailed chemical kinetic mechanism was developed to describe the pyrolysis, oxidation, and autoignition of methanol, DME and DMM at high pressures. The mechanism predicts autoignition delay time under Diesel-like conditions.

The comprehensive engine simulation code, WAVE, is extended to include a knock sub-model. A hydrocarbon autoignition model based on a degenerate chain-branching mechanism that constitutes the basic kinetic framework was modified and coupled with WAVE's engine thermodynamic environment for this purpose. Making use of this modified hydrocarbon autoignition model and the flow based in-cylinder heat transfer model in WAVE, the original rapid compression machine (RCM) experiments of Shell can be reproduced reasonably well. In addition, a spatially and temporally resolved end-gas thermodynamic model was developed to allow a more accurate calculation of the end-gas temperature over the combustion chamber wall. The developed end-gas thermodynamic-driven knock model further assumes the existence of a pseudo-boundary-layer temperature profile which is linearly distributed between the unburned end-gas and the wall.

Flight Inspection is the Quality Assurance program which the Federal Aviation Administration uses to verify the performance of air navigation facilities and associated Instrument Flight Procedures. As an integral part of the National Airspace System, it is imperative that these facilities and procedures conform to the prescribed standards throughout their published service volume. This paper attempts to explain to the reader just how the FAA uses their Flight Inspection aircraft to accomplish that mission.

Recent technology advancements in hardware and software has allowed the emergence of the PC as a cost effective aircraft design/analysis platform. Software packages such as CSI-CADD, Vellum Solids, and AeroPack provide “Lockheed” class modeling tools for a wide variety of design projects. Modeling tools for airfoils, wings, and polyconic surfaces are discussed as well as data extraction methods for wetted areas, volumes, centroids, area curves, obscuration plots, meshing, and custom interfaces to design analysis programs such as GA-CAD.

This study is aimed at developing requirements for certification criteria and verification techniques for side facing aircraft seats. Presently flying side facing seats were inspected and analyzed. Results from automotive safety research were used and transferred to aircraft. For lateral strain direction, on the one hand human tolerance, and on the other hand injury criteria such as head, cervical column, thoracic/lumbar column, thorax, pelvis as well as upper and lower extremities were compiled from literature. The particularities of side facing seats were inspected with two dynamic tests, and proposals made for the requirements of certification criteria and verification techniques.

The calculation of reliable indexes of oil contamination caused by engine wear is necessary in order to use oil analysis as a failure diagnostic tool. In this paper, a method for the correction of the measurements obtained from oil spectrometric analysis is proposed. A realistic model must consider the combined effects of the oil filter efficiency, the oil consumption and the amount of fresh oil added. The concentration of contaminants is normalized taking into account all the above effects with the assumption of a constant contamination rate. At the beginning of the study the repeatability of the measuring equipment and the effect of the method of obtaining the samples were calculated. Three factors were considered: the location which the sample was taken from (the oil pan drain plug or the oil level dipstick orifice), the engine temperature (cold and warm) and the time delay from sample taking to its analysis.

This paper reports on a continuing Ohio Department of Transportation (ODOT) two year evaluation of a biodiesel blend, B20, (an 80/20 blend of diesel fuel and methyl soyate) in fleet operations. The evaluation is being conducted in two adjacent counties in northwest Ohio. The Fulton county ODOT garage has been operating all diesel powered equipment on B20 since March of 1996 and has been comparing operating results with counterpart equipment in nearby Williams county which has continued operations on diesel fuel. The results of this test are being monitored by Battelle which is collecting and analyzing detailed operational and reliability data on five (5) Navistar-International dump truck / snow plows in each county. Chassis dynamometer evaluation of engine power changes, “before/after” snap-idle smoke tests, identification of cold weather issues, and the consistency of on-site fuel blending have been conducted and are discussed in this paper.

In order to document the level of exhaust emisions from biodiesel fuels compared with conventional diesel fuels, several studies have been conducted throughout the world. The results of these studies are, however, not conclusive, and very few reports exist on the potential health risk caused by exhaust emissions from biofuels. The aim of this investigation is to examine the chemical characteristics of exhaust emissions from Rapeseed oil Methyl Ester (RME) compared with a modern diesel fuel, and to document the potential health risk associated with these fuels.

Fuel efficient engine oils containing molybdenum dialkyldithiocarbamate, MoDTC, friction modifiers can lose their ability to reduce friction during service prematurely. Depletion processes involving antioxidant reactions and interactions with other additives play important roles in determining the performance of these formulations. This paper describes results from investigations of the antioxidant reactions of MoDTC alone and in combinations with zinc dialkyldithiophosphates and a phenolic antioxidant. The effect of supplementary ashless antioxidant on retention of friction reducing capability is described.

Lubricating oil viscosity is commonly measured by the kinematic method as outlined in ASTM 0445. This method is also used to measure drain oil viscosity as an indicator of soot induced thickening. Drain oils can contain solid particles and exhibit non-Newtonian flow behavior. This paper discusses the use of rotational rheometers to measure the rheology of drain oils. These instruments have been used for many years in other industries (food, paints and coatings) to measure particle filled, non- Newtonian fluids. The rotational method yields the general flow curve of viscosity versus shear rate as compared to the single point, low shear kinematic viscosity measurement. The rotational method includes the kinematic viscosity single point but also yields significantly more information on shear behavior. Both pumpability (low shear) and flowability(higher shear) can be ascertained from the rotational method.

Fundamental knowledge investigations of soot-lubricant interactions continue. In earlier work [1-2], we examined the impact of formulation variables, engine type and mode of engine operation on the formation and nature of diesel soot and its interactions with the crankcase lubricant. Three types of North American heavy duty diesel engines were utilized: Mack EM6-285, GM 6.2L and GM 6.5L. Experiments identified additive compositions capable of providing good viscosity and wear control. Furthermore, we identified soot agglomeration, rather than amount of soot, as the phenomenon responsible for roller follower wear at low dispersant levels. Oil thickening results from the level of soot contamination, in combination with the “state” of the soot. The latter is noticeably affected by the lubricant dispersant level. Part 4 of our studies examines the impact of oil composition on a fluid's ability to handle soot in the Mack T-8 Test.

Biodiesel is a mixture of esters (usually methyl esters) of fatty acids found in the triglycerides of vegetable oils. The different fatty compounds comprising biodiesel possess different ignition properties. To investigate and potentially improve these properties, the cetane numbers of various fatty acids and esters were determined in a Constant Volume Combustion Apparatus. The cetane numbers range from 20.4 for linolenic acid to 80.1 for butyl stearate. The cetane numbers depend on the number of CH2 groups as well as the number of double bonds and other factors. Various oxygenated compounds were studied for their potential of improving the cetane numbers of fatty compounds. Several potential cetane improvers with ignition delay properties giving calculated cetane numbers over 100 were identified. The effect of these cetane improvers depended on their concentration and also on the fatty material investigated.

Methyl esters from vegetable oils (biodiesel) are very attractive as alternative fuels for combustion in direct injection compression-ignition (diesel) engines. Biodiesel fuels have low-temperature flow properties that limit utilization during cooler weather in moderate temperature climates. Although winterization reduces the cloud point (CP) of methyl soyate from 0 to -2O°C, liquid product yields were relatively low (0.30-0.33 g/g). Winterization of methyl soyate-cold flow improver mixtures decreased CP by -11°C and increased yields to 0.80-0.87 g/g. Winterization of methyl soyate from hexane and isopropanol solvents gave similar results. Differential scanning calorimetry (DSC) analyses showed that nucleation mechanisms of methyl esters were significantly affected by winterization.