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Significant efforts have been made in the research of Pulsed Detonation Engines (PDEs) to increase the reliability and longevity of detonation based propulsion systems for use in manned aircraft. However, the efficiency, durability, and low mechanical complexity of PDEs opens up potential for use in disposable unmanned-vehicles. This paper details the steps taken for producing a miniaturized pulse detonation engine at West Virginia University (WVU) to investigate the numerically generated constraining dimensions for Deflagration to Detonation Transition (DDT) cited in this paper. Initial dimensions for the WVU PDE Demonstrator were calculated using fuel specific DDT spatial properties featured in the work of Dr. Phillip Koshy Panicker, of The University of Texas at Arlington. The WVU demonstrator was powered using oxygen and acetylene mixed in stoichiometric proportions.

Tube Launched-Unmanned Air Vehicles (TL-UAV) are munitions that alter their trajectories during flight to enhance the capabilities by possibly extending range, increasing loiter time through gliding, and/or having guided targeting capabilities. Traditional munition systems, specifically the tube-launched mortar rounds, are not guided. Performance of these "dumb" munitions could be enhanced by updating to TL-UAV and still utilize existing launch platforms with standard propellant detonation firing methods. The ability to actively control the flight path and extend range of a TL-UAV requires multiple onboard systems which need to be identified, integrated, assembled, and tested to meet cooperative function requirements. The main systems, for a mortar-based TL-UAV being developed at West Virginia University (WVU), are considered to be a central hub to process information, aerodynamic control devices, flight sensors, a video camera system, power management, and a wireless transceiver.

Until a proper fueling infrastructure is established, vehicles powered by natural gas must have bi-fuel capability in order to avoid a limited vehicle range. Although bi-fuel conversions of existing gasoline engines have existed for a number of years, these engines do not fully exploit the combustion and knock properties of both fuels. Much of the power loss resulting from operation of an existing gasoline engine on compressed natural gas (CNG) can be recovered by increasing the compression ratio, thereby exploiting the high knock resistance of natural gas. However, gasoline operation at elevated compression ratios results in severe engine knock. The use of variable intake valve timing in conjunction with ignition timing modulation and electronically controlled exhaust gas recirculation (EGR) was investigated as a means of controlling knock when operating a bi-fuel engine on gasoline at elevated compression ratios.

This is the second of two papers that examine the future effectiveness of the California greenhouse gas “GHG” program and the federal fuel economy program established in the Energy Independence and Security Act of 2007 (“EISA 2007”) in controlling greenhouse gases. SAE 2008-01-1852 estimates the fuel economy levels that the California and federal programs can be expected to require, under assumptions stated in that paper. This paper applies those fuel economy estimates to examine the impact of the California and federal programs on lifecycle emissions of GHGs and carbon dioxide (“CO2”). EISA 2007 not only proposes to improve car and LDT fuel economy, but it also proposes to reduce GHGs through its Renewable Fuel Standards (“RFS”) provisions, which are likely to lead to substantial expansion in the use of 85% ethanol gasoline blends (E85).

Dedicated natural gas engines suffer the disadvantages of limited vehicle range and relatively few refueling stations. A vehicle capable of operating on either gasoline or natural gas allows alternative fuel usage without sacrificing vehicle range and mobility. However, the bi-fuel engine must be made to provide equal performance on both fuels. Although bi-fuel conversions have existed for a number of years, historically natural gas performance is degraded relative to gasoline due to reduced volumetric efficiency and lower power density of CNG. Much of the performance losses associated with CNG can be overcome by increasing the compression ratio. However, in a bi-fuel application, high compression ratios can result in severe engine knock during gasoline operation. Variable intake valve timing, increased exhaust gas recirculation and retarded ignition timing were explored as a means of controlling knock during gasoline operation of a bi-fuel engine.

The importance of the fuel in providing improved vehicle performance and reduced emissions has become widely recognized in the past ten years. However, few if any systematic analyses of gasoline quality have ever been published. A methodology has been developed for analyzing the vehicle performance and emissions characteristics of gasolines. It has been applied to data obtained from surveys of United States' service station gasoline samples obtained in 23 cities during 1996. Results are presented for: gasoline type (California RFG - reformulated gasoline, Federal RFG, low RVP - Reid Vapor Pressure, and conventional); gasoline grade (regular, intermediate and premium); individual cities; individual brands (coded); and for sulfur content, the fuel property with the greatest current interest. It is concluded that large differences exist among commercial gasolines for all of the items evaluated.

As the demand for higher engine efficiencies and lower emissions drive stationary, spark-ignited reciprocating engine combustion to leaner air/fuel operating conditions and higher in-cylinder pressures, increased spark energy is required for maintain stable combustion and low emissions. Unfortunately, increased spark energy negatively impacts spark plug durability and its effectiveness in transmitting adequate energy as an ignition source. Laser ignition offers the potential to improve ignition system durability, reduce maintenance, as well as to improve engine combustion performance. This paper discusses recent engine combustion testing with an open beam path laser ignition system in a single-cylinder engine fueled by natural gas. In particular, engine knock and misfire maps are developed for both conventional spark plug and laser spark ignition. The misfire limit is shown to be significantly extended for laser ignition while the knock limit remains virtually unaffected.

Two and three-dimensional test cases were simulated using a detailed kinetic mechanism for di-methyl ether to represent methane combustion. A piston-bowl assembly for the compression and expansion strokes with combustion has been simulated at 1500 RPM. A fine grid was used for the 2-D simulations and a rather coarse grid was used for the 3-D calculations together with a k-ε subgrid-scale turbulence model and a partially stirred reactor model with three time scales. Ignition was simulated artificially by increasing the temperature at one point inside the cylinder. The results of these simulations were compared with experimental results. The simulation involved an engine with a homogeneous charge of methane as fuel. Results indicate that pressure fluctuations were captured some time after the ignition started, which indicates knock conditions.

The Distillation Index (DI) is a measure of the volatility of gasoline, especially its tendency to vaporize in an engine at initial start-up and during warm up. On January 27, 1999 the U.S. domestic and import automotive manufacturers petitioned the US EPA to limit the DI of all U.S. gasoline to 1200 degrees Fahrenheit as a means of reducing in-use emissions and ensuring consistent cold start and warm-up driveability.[1] Air Improvement Resource, Inc. (AIR) completed a 1999 study that evaluated the benefits of a DI cap. Overall, the 1999 AIR study estimated that the DI cap would produce a 16 and 15 percent reduction in hydrocarbon (HC) and carbon monoxide (CO) exhaust, respectively, from gasoline vehicles nationally in 2020. [2] In 2000, the Alliance of Automobile Manufacturers sponsored a more compreshensive examination of the emission consequences of the DI cap on which this paper is based.

In 2008-2009, EPA and DOE tested fifteen 2008 model year Tier 2 vehicles on 27 fuels. The fuels were match-blended to specific fuel parameter targets. The fuel parameter targets were pre-selected to represent the range of fuel properties from fuel survey data from the Alliance of Automobile Manufacturers for 2006. EPA's analysis of the EPAct data showed that higher aromatics, ethanol, and T90 increase particulate matter (PM) emissions. EPA focused their analysis only on the targeted fuel properties and their impacts on emissions, namely RVP, T50, T90, aromatics, and ethanol. However, in the process of fuel blending, at least one non-targeted fuel property, the T70 distillation parameter, significantly exceeded 2006 Alliance survey parameters for two of the E10 test fuels. These two test fuels had very high PM emissions. In this study, we examine the impacts of adding T70 as an explanatory variable to the analysis of fuel effects on PM.

Evermore demanding market and legislative pressures require stationary lean burn natural gas engines to operate at higher efficiencies and reduced levels of emissions. Higher in-cylinder pressures and leaner air/fuel ratios are required in order to meet these demands. The performance and durability of spark plug ignition systems suffer as a result of the increase in spark energy required to maintain suitable engine operation under these conditions. Advancing the state of the art of ignition systems for these engines is critical to meeting increased performance requirements. Laser-spark ignition has shown potential to improve engine performance and ignition system durability to levels required meet or exceed projected requirements. This paper discusses testing which extends previous efforts [1] to include constant fueling knock, misfire, thermal efficiency, and NOx emissions mapping of a single cylinder lean burn natural gas engine.

The importance of the fuel in providing improved vehicle performance and reduced emissions has become widely recognized, especially in the past ten years. In 1998, an SAE paper was presented providing a systematic analyses of 1996 United States gasoline quality. This paper extends the methodology of that paper to include the impact of fuel composition on evaporative emissions, and it provides analyses of gasoline quality for the years of 1996, 1997 and 1998. The vehicle performance and emissions characteristics of gasolines were determined using data from surveys of United States' service station gasoline samples. Results are presented for: gasoline type (California RFG - reformulated gasoline, Federal RFG, low RVP - Reid Vapor Pressure, and conventional); gasoline grade (regular, intermediate and premium); individual cities; individual brands (coded); and for sulfur content.

Hydrogen Internal Combustion Engine (ICE) vehicles using a traditional ICE that has been modified to use hydrogen fuel are an important mid-term technology on the path to the hydrogen economy. Hydrogen-powered ICEs that can run on pure hydrogen or a blend of hydrogen and compressed natural gas (CNG) are a way of addressing the widespread lack of hydrogen fuelling infrastructure in the near term. Hydrogen-powered ICEs have operating advantages as all weather conditions performances, no warm-up, no cold-start issues and being more fuel efficient than conventional spark-ignition engines. The Wankel engine is one of the best ICE to be converted to run hydrogen. The paper presents some details of an initial investigation of the CAD and CAE modeling of a novel design where two jet ignition devices per rotor are replacing the traditional two spark plugs for a faster and more complete combustion.