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The Homogeneous Charge Compression Ignition (HCCI) combustion concept is currently under widespread investigation due to its potential to increase thermal efficiency while greatly decreasing harmful exhaust pollutants. Simulation tools have been developed to explore the implications of initial mixture thermodynamic state on engine performance and emissions. In most cases these modeling efforts have coupled a detailed fuel chemistry mechanism with empirical descriptions of the in-cylinder heat transfer processes. The primary objective of this paper is to present a fundamentally based boundary layer heat transfer model. The two-zone combustion model couples an adiabatic core zone with a boundary layer heat transfer model. The model predicts film coefficient, with approximately the same universal shape and magnitudes as an existing global model.

When automobile hydrocarbons are exhausted into the atmosphere in the presence of NOx and sunlight, ground-level ozone is formed. While researchers have used Maximum Incremental Reactivity (MIR) factors to estimate ozone production, this procedure often overestimates Local Ozone Production (LOP) because it does not consider local atmospheric conditions. In this paper, an enhanced MIR methodology for estimating actual LOP attributable to a vehicle in a particular ozone problem area is presented. In addition to using tabulated MIR factors, the procedure also uses local hydrocarbon reaction terms and a relative mechanistic reactivity term that account for local atmospheric conditions. Through this approach, the effects of hydrocarbon reaction rates, hydrocarbon residence times, and prevailing HC/NOx ratio are accounted for. The procedure is intended to enable automotive engineers to more realistically estimate actual local ozone production resulting from hydrocarbon emissions.

The U.S. Renewable Fuel Standard (RFS2) requires an increase in the use of advanced biofuels up to 36 billion gallons by 2022. Longer chain alcohols, in addition to cellulosic ethanol and synthetic biofuels, could be used to meet this demand while adhering to the RFS2 corn-based ethanol limitation. Higher carbon number alcohols can be utilized to improve the energy content, knock resistance, and/or petroleum displacement of gasoline-alcohol blends compared to traditional ethanol blends such as E10 while maintaining desired and regulated fuel properties. Part I of this paper focuses on the development of scenarios by which to compare higher alcohol fuel blends to traditional ethanol blends. It also details the implementation of fuel property prediction methods adapted from literature. Possible combinations of eight alcohols mixed with a gasoline blendstock were calculated and the properties of the theoretical fuel blends were predicted.

A primary goal of large eddy simulation, LES, is to capture in-cylinder cycle-to-cycle variability, CCV. This is a first step to assess the efficacy of 35 consecutive computed motored cycles to capture the kinetic energy in the TCC-III engine. This includes both the intra-cycle production and dissipation as well as the kinetic energy CCV. The approach is to sample and compare the simulated three-dimensional velocity equivalently to the available two-component two-dimensional PIV velocity measurements. The volume-averaged scale-resolved kinetic energy from the LES is sampled in three slabs, which are volumes equal to the two axial and one azimuthal PIV fields-of-view and laser sheet thickness. Prior to the comparison, the effects of sampling a cutting plane versus a slab and slabs of different thicknesses are assessed. The effects of sampling only two components and three discrete planar regions is assessed.

Results of three-dimensional steady flow calculations are compared with existing pressure and velocity-measurements of two manifold-type junctions. The junctions consist of a main duct and a side branch, both with the same rectangular cross section, with the side branch joining the main duct at an angle of either 90 or 45 degrees. Both combining and dividing flow configurations are considered for different total mass flow rates and different side-branch-to-main-duct mass flow ratios. One objective of this investigation was to assess the effects of numerical differencing scheme and mesh refinement on solution accuracy, and both parameters showed strong influences on the computed results. It is shown that calculations should be made with the highest possible level of numerical accuracy and grid resolution in regions of flow recirculation. Comparisons of computed and measured velocities, static pressures, and flow loss coefficients are presented in this paper.

A global, systems-level model which characterizes the thermal behavior of internal combustion engines is described in this paper. Based on resistor-capacitor thermal networks, either steady-state or transient thermal simulations can be performed. A two-zone, quasi-dimensional spark-ignition engine simulation is used to determine in-cylinder gas temperature and convection coefficients. Engine heat fluxes and component temperatures can subsequently be predicted from specification of general engine dimensions, materials, and operating conditions. Emphasis has been placed on minimizing the number of model inputs and keeping them as simple as possible to make the model practical and useful as an early design tool. The success of the global model depends on properly scaling the general engine inputs to accurately model engine heat flow paths across families of engine designs. The development and validation of suitable, scalable submodels is described in detail in this paper.

Predicting the effects of transient heat conduction in low-heat-rejection engine components have been analyzed by applying instantaneous boundary conditions throughout a diesel engine thermodynamic cycle. This paper describes the advantages and disadvantages of one-dimensional finite difference and two-dimensional finite element methods by analyzing simple and complicated geometries like diesel bowl-in pistons. Also the performance characteristics of plasma sprayed zirconia, partially stabilized zirconia, and a monolithic reaction bonded silicon nitride ceramic materials are discussed and compared. Finite element studies have indicated that the steep temperature gradients associated with cyclic temperature swings in excess of 400 K may contribute to the failure of ceramic coatings near the corner joining the surface of the piston and the surface of the bowl for bowl-in pistons.