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A free piston internal combustion (IC) engine operating on high compression ratio (CR) homogeneous charge compression ignition (HCCI) combustion is being developed by Sandia National Laboratories to significantly improve the thermal efficiency and exhaust emissions relative to conventional crankshaft-driven SI and Diesel engines. A two-stroke scavenging process recharges the engine and is key to realizing the efficiency and emissions potential of the device. To ensure that the engine's performance goals can be achieved the scavenging system was configured using computational fluid dynamics (CFD), zero- and one-dimensional modeling, and single step parametric variations. A wide range of design options was investigated including the use of loop, hybrid-loop and uniflow scavenging methods, different charge delivery options, and various operating schemes. Parameters such as the intake/exhaust port arrangement, valve lift/timing, charging pressure and piston frequency were varied.

A novel direct-fabrication technique (robocasting) was used to produce periodic lattices of ceramic rods. The macrostructure is a three-dimensional mesh with controlled porosity in all dimensions but no line-of-sight pathways. These ceramic lattices can function as catalyst supports for gas combustion, and possibly self-regenerating filters for diesel particulates. Compared to the traditional two-dimensional “honeycomb” structured extrudates, the three-dimensional structures have high surface to volume ratios and highly turbulent flow. The flow behaviors of these ceramic lattices and the resulting enhancements in catalytic performance over traditional supports have been demonstrated for propane and methane combustion. Similar tests are underway for the selective catalytic reduction (SCR) of NOx. The potential utility of these structures for diesel particulate trapping will also be discussed.

Simultaneous measurements of the radial and the tangential components of velocity are obtained in a high-speed, direct-injection diesel engine typical of automotive applications. Results are presented for engine operation with fuel injection, but without combustion, for three different swirl ratios and four injection pressures. With the mean and fluctuating velocities, the r-θ plane shear stress and the mean flow gradients are obtained. Longitudinal and transverse length scales are also estimated via Taylor's hypothesis. The flow is shown to be sufficiently homogeneous and stationary to obtain meaningful length scale estimates. Concurrently, the flow and injection processes are simulated with KIVA-3V employing a RNG k-ε turbulence model. The measured turbulent kinetic energy k, r-θ plane mean strain rates ( 〈Srθ〉, 〈Srr〉, and 〈Sθθ〉 ), deviatoric turbulent stresses , and the r-θ plane turbulence production terms are compared directly to the simulated results.

General corrosion protection of sheet materials such as steel used in automobile construction has reached a high level of performance, due primarily to the incorporation of mill-applied treatments such as electrogalvanizing, galvannealing and other coil-coating processes developed over the last half century. While such treatments have greatly extended the corrosion resistance of steel and its various body constructs, attention is now focused on aspects of the manufacturing process wherein these intended protections are compromised by such features as weldments, joins, cut edges and extreme metal deformations such as hems. A novel metal deposition process, based on high-velocity impact fusion of solid metal particles, has been used to extend the corrosion resistance of base steel and pre-galvanized sheet, by selectively placing highly controlled depositions of zinc and other sacrificial materials in close proximity to critical manufacturing details.

The diffusion flame lift-off length of isolated, free diesel jets in quiescent atmospheres is known to have a strong influence on soot formation by affecting fuel/air mixing prior to combustion. In realistic engine environments, the proximity and temperature of in-cylinder surfaces, in-cylinder gas flows (swirl), and interactions between adjacent jets may affect the behavior of the flame lift-off, and thereby affect soot formation. To better understand the influence of these factors on the lift-off length and on soot formation, optical imaging diagnostics were employed to measure the flame lift-off length in an optically-accessible heavy-duty Direct Injection (DI) diesel engine. A two-camera OH chemiluminescence diagnostic was developed and employed to measure the flame lift-off length for a range of injector nozzle geometries and engine operating conditions.