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We describe a method for detecting and quantifying time irreversibility in experimental engine data. We apply this method to experimental heat-release measurements from four spark-ignited engines under leaning fueling conditions. We demonstrate that the observed behavior is inconsistent with a linear Gaussian random process and is more appropriately described as a noisy nonlinear dynamical process.

The goal of this investigation was to gain a better understanding of the effect of fuel/air charge composition on the dynamical structure of cyclic dispersion in lean-fueled spark ignition engines. Swirl and fuel injection timing were varied on a single-cylinder research engine to investigate the effects of charge motion and stratification on prior-cycle effects under lean operating conditions. Temporal patterns in the cycle-to-cycle combustion dynamics were analyzed using return maps, Shannon entropy, and symbol sequence statistics. Our results indicated a transition from stochastic behavior to noisy nonlinear determinism as equivalence ratio was decreased from near stoichiometric to very lean conditions. The equivalence ratio at which deterministic effects became important was strongly influenced by swirl and fuel injection timing. A comparison of our results and previous results from an eight-cylinder production engine showed similar trends.

Computational fluid dynamics simulations of fixed-bed adiabatic adsorption/desorption processes are presented in this paper. Linear driving force model is used for heat and mass transfer rates. A two-dimensional cylindrical canister and three-dimensional automotive production canister geometry are used to study the adsorption/desorption processes of carbon dioxide in helium carrier gas on Norit B4 activated carbon. The two-dimensional results compare well with the results of Hwang et al. [1]. Computational results as breakthrough curve, adsorption amount and temperature profiles are provided. Results show that non-adiabatic model should be used to fully utilize the activated carbon bed capacity prior to breakthrough.

A detailed investigation of the intake port mixing process was performed on a fired single cylinder port fuel injected research engine. The liquid fuel droplets were studied using several different methods of analysis ranging from spatially and temporally resolved to spatially and temporally averaged data. Comparisons of the port mixture preparation results were made to the combustion performance of the engine in order to develop correlations between the mixing process and resulting engine performance. It is suggested that while the nature of the fuel spray produced by the injector is important, there are several other factors that influence fuel delivery to the cylinder. Calculations are given that indicate drops must be very small to entrain in the flow and avoid wall wetting. Secondary drop formation mechanisms may ultimately determine the nature of the fuel delivery to the cylinder and have an impact on combustion performance.

The objective of this paper is to develop a comprehensive non-linear finite element model for determining failure behavior of hydrogen composite storage cylinders subjected to high pressure and flame impingements. A resin decomposition model is implemented to predict the residual resin content. A material degradation model is used to account for the loss of moduli. A failure model based on Hashin's failure theory is implemented to detect various types of composite failure. These sub-models are implemented in ABAQUS finite element code using user subroutine. Numerical results are presented for thermal damage, residual properties and resin content.

The goal of this work is to begin to understand and characterize the break-up of liquid fuel as it is torn from intake valve and port surfaces during the start-up period of a spark ignition engine. The lack of vaporization from warm engine surfaces causes the fuel to enter the combustion chamber as large droplets. Atomization results from the shearing effect of the intake air as it is pulled into the combustion chamber. Droplet sizes, air velocities, and break-up formations are studied using a high-resolution CCD camera and strobe. Indolene and iso-octane fuels are used to consider the effect of fuel properties on the break-up. The atomization processes that occur are characterized through the use of dimensionless groups. Results show that the fuel break-up follows the same processes seen for many other atomizing devices under the influence of co-flowing air. The role of valve gap, liquid fuel flowrate, air flowrate, and valve dimensions on the break-up process are discussed.

Two soot-containing turbulent non-premixed flames burning gaseous acetylene in atmospheric-pressure air were investigated by conducting non-intrusive optical experiments at various flame locations. The differences in burner exit Reynolds numbers of these flames were large enough to examine the influence of flow dynamics on soot formation and evolution processes in heavily-sooting flames. By accounting for the fractal nature of aggregated primary particles (spherules), the proper interpretation of the laser scattering and extinction measurements yielded all the soot parameters of principal interest. With the separation of spherule and aggregate sizes, the axial zones of the prevailing turbulent soot mechanisms were accurately identified. With the high propensity of acetylene fuel to soot, relatively fast particle nucleation process led to high concentrations immediately above the burner exit.

A comprehensive study is reported on the dynamics of critical components in the refueling process for passenger cars and light trucks. Nozzle, filler pipe, recirculation tube, tank, and canister are investigated. CFD simulations are conducted for flow rates of 4 liters/min (lpm) to 80 lpm for gasoline and up to 120 lpm for diesel fuel. Tank pressure, identified as a critical parameter controlling flow performance, is measured and utilized as a boundary condition. Flow simulation in a carbon canister, accomplished by treating the adsorbing carbon as a porous medium, indicates pressure drops which are in good agreement with published experimental data. Experiments have been conducted and used to validate simulation results. The simulations indicate that CFD can be successfully utilized as a tool to shorten the design, development and cost reduction cycle of a nozzle, filler pipe, canister, and tank system.

Automotive refueling is gaining greater importance because fuel vapors released during refueling are believed to increase ozone levels in urban areas. As a step towards On-Board Refueling Vapor Recovery (ORVR) designs, vapor generation and transport during refueling needs to be understood to develop recovery techniques. The objective of the present study is to understand the fluid flow inside the automotive gas tank filler pipe using commercially available Computational Fluid Dynamics (CFD) software. This effort is expected to yield detailed flow field information, including air entrainment. The phenomena of well-back, the process of fuel flooding the filler pipe and flowing backwards at the filler pipe mouth, and the pressure transients inside the tank leading to premature nozzle shut-off were examined. The current work includes unsteady CFD simulation with gasoline and air as the working fluids.