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An experimental investigation was conducted using a Ford single-cylinder spark-ignition research engine to compare the performance and emissions of neat n-butanol fuel to that of gasoline and ethanol. Measurements of brake torque and exhaust gas temperature along with in-cylinder pressure traces were used to study the performance of the engine and measurements of emissions of unburned hydrocarbons, carbon monoxide, and nitrogen oxide ere used to compare the three fuels in terms of combustion byproducts. It was found that gasoline and butanol are closest in engine performance with butanol producing slightly less brake torque. Exhaust gas temperature and nitrogen oxide measurements show that butanol combusts at a lower peak temperature. Of particular interest were the emissions of unburned hydrocarbons which were between two and three times those of gasoline suggesting that butanol is not atomizing as effectively as gasoline and ethanol.

An optically accessible single-cylinder high-speed direct-injection (HSDI) diesel engine equipped with a Bosch common rail injection system was used to study effects of injection pressures on the in-cylinder spray and combustion processes. An injector with an injection angle of 70 degrees and European low sulfur diesel fuel (cetane number 54) were used in the work. The operating load was 2.0 bar IMEP with no EGR added in the intake. The in-cylinder pressure was measured and the heat release rate was calculated. High-speed Mie-scattering technique was employed to visualize the liquid distribution and evolution. High-speed combustion video was also captured for all the studied cases using the same frame rate. NOx emissions were measured in the exhaust pipe. The experimental results indicated that for all of the conditions the heat release rate was dominated by a premixed combustion pattern. Two-stage low temperature reaction was seen for early injection timings.

A single nozzle port fuel injector was modified to apply electrostatic charge to the fuel stream, with the intention of studying electrostatically assisted sprays in a practical, port-injected engine. The modifications were kept external to the injector and involved placing an electrode and insulating liner over the tip of the injector. The performance of the modified injector, which combined pressure driven and electrostatic atomization, was characterized in three phases: the injector sprays themselves were studied, combustion of charged fuel droplets was studied, and the injector was installed and tested on a single cylinder spark ignition engine. In the first phase, Fraunhofer diffraction measurements of droplet size, and particle image velocimetry measurements of droplet velocity were performed. The charge transferred by the sprays was measured using an electrometer, and typical forces exerted on droplets in the sprays were estimated.

Combustion processes employing different injection strategies in a High-Speed Direct Inject (HSDI) diesel engine were investigated using a narrow angle injector (70 degree). Whole-cycle combustion was visualized using a high-speed digital video camera. The liquid spray evolution process was imaged by the Mie-scattering technique. Different injection strategies were employed in this study including early pre-Top Dead Center (TDC) injection, post-TDC injection, multiple injection strategies with an early pre-TDC injection and a late post-TDC injection. Smokeless combustion was obtained under some operating conditions. Compared with the original injection angle (150 degree), some new combustion phenomena were observed for certain injection strategies. For early pre-TDC injection strategies, liquid fuel impingement is observed that results in some newly observed fuel film combustion flame (pool fires) following an HCCI-like weak flame.

Low Temperature Compression Ignition (LTCI) combustion employing multiple injection strategies in an optically accessible single-cylinder small-bore High-Speed Direct-Injection (HSDI) diesel engine equipped with a Bosch common-rail electronic fuel injection system was investigated in this work. Heat release characteristics were analyzed through the measurement of in-cylinder pressure. The whole cycle combustion process was visualized with a high-speed digital video camera by imaging natural flame luminosity and three-dimensional like combustion structures were obtained by taking flame images from both the bottom of the optical piston and the side window. The transient in-cylinder late cycle soot distribution was obtained by applying a Backward Illumination Light Extinction (BILE) technique through side windows. Based on the flame luminosity and soot spatially integrated signal, new parameters were defined to evaluate the combustion performance and soot formation characteristics.

An optically accessible single cylinder small-bore HSDI diesel engine equipped with a Bosch common-rail injection system was used to study the effects of multiple injection strategies on the in-cylinder combustion processes. The operating conditions were considered typical in the metal engine under moderate load conditions. In-cylinder pressure traces are used to analyze heat release characteristics. The combustion modes transit from the Homogeneous Charge Compression Ignition (HCCI)-like combustion mode to conventional diesel combustion by changing injection parameters. The whole cycle combustion process was visualized through a high-speed digital video camera and the combustion images clearly show the combustion mode transition. Laser-Induced Exciplex Fluorescence (LIEF) technique was used to obtain simultaneous liquid and vapor fuel distributions within the combustion chamber, with tetradecane-TMPD-naphthalene as the base fuel-dopant combination.

Homogeneous Charge Compression Ignition (HCCI) combustion employing single main injection strategies in an optically accessible single cylinder small-bore High-Speed Direct Injection (HSDI) diesel engine equipped with a Bosch common-rail electronic fuel injection system was investigated in this work. In-cylinder pressure was taken to analyze the heat release process for different operating parameters. The whole cycle combustion process was visualized with a high-speed digital camera by imaging natural flame luminosity. The flame images taken from both the bottom of the optical piston and the side window were taken simultaneously using one camera to show three dimensional combustion events within the combustion chamber. The engine was operated under similar Top Dead Center (TDC) conditions to metal engines. Because the optical piston has a realistic geometry, the results presented are close to real metal engine operations.

An optically-accessible single cylinder small-bore HSDI diesel engine equipped with a Bosch common-rail injection system is used to study the effects of differing injection strategies on combustion and soot. Laser-Induced Incandescence (LII) is used to visualize the evolution and distribution of soot within the combustion chamber from the onset of ignition to late into the expansion stroke. A low-sooting fuel, blended from two single component fuels, is used for experimentation. Because of the low-sooting nature of the fuel blend, the lean operating conditions, and optical distortion of the complex shaped engine, acceptable LII signal levels are difficult to obtain. Therefore a low-sulfur European Diesel fuel is also employed during experimentation. Acceptable LII signal levels are obtained using the Diesel fuel, however, without extreme caution, surface damage to the optical components of the engine are possible.

An optically-accessible single cylinder small-bore HSDI diesel engine equipped with a Bosch common-rail injection system is used to study the effects of multiple injection. High-speed video is used to study the injector and spray behavior. Laser-induced exciplex fluorescence is used to obtain simultaneous liquid and vapor fuel distributions within the combustion chamber, with tetradecane-TMPD-naphthalene as the base fuel-dopant combination. Significant liquid impingement is seen in the single main injection case, while evidence of liquid impingement is seen only in the first stage of the multiple injection case. No appreciable liquid impingement is seen for the second stage of the multiple injection case. Vapor is seen throughout the jet cross-section regardless of the injection parameters. The majority of the vapor is confined to the bowl region in the single injection case while evidence of vapor is seen outside of the bowl for the multiple injection case.