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Effects of methyl ester biodiesel fuel blends on NOx emissions are studied experimentally and analytically. A precisely controlled single cylinder diesel engine experiment was conducted to determine the impact of a 20% blend of soy methyl ester biodiesel (B20) on NOx emissions. The data were then used to calibrate KIVA chemical kinetics models which were used to determine how the biodiesel blend affects NOx production during the combustion process. In addition, the impact on the engine control system of the lower specific energy content of biodiesel was determined. Both factors, combustion and controls, must be taken into account when determining the net NOx effect of biodiesel compared to conventional diesel fuel. Because the magnitude and even direction of NOx effect changes with engine load, the NOx effect associated with burning biodiesel blends over a duty cycle depends on the duty cycle average power and fuel cetane number.

The use of engine simulation is rapidly increasing throughout the engine industry. In the present paper, the major contributing factors which drive this trend are discussed. These include the increasing sophistication of the simulations, both in the area of high accuracy and in user-friendliness. Also, the decreasing cost of engineering computer workstations places them on the desktop of engineers and makes them readily available. Furthermore, the steadily rising computer processing power now provides the response needed in the engine development environment. The advances seen in simulations now open a new area for their application--as a tool fully complementary to test and measurement in a “concurrent test and simulation” process. The wide-ranging benefits and opportunities offered by the process are described in detail.

In-cylinder flows in four-valve SI engines were examined by high frame rate flow visualization and two-component LDV measurement. It is believed that the tumble and swirl motion generated during intake breaks down into small-scale turbulence later in the cycle. The exact nature of this relationship is not well known. However, control of the turbulence offers control of the combustion process. To develop a better physical understanding of the in-cylinder flow, the effects of the cylinder head intake port configuration and the piston geometry were examined. For the present study, a 3.5L, four-valve engine was modified to be mounted on an AVL single cylinder research engine type 520. A quartz cylinder was fabricated for optical access to the in-cylinder flow. Piston rings were replaced by Rulon-LD rings. A Rulon-LD ring is advantageous for the optical access as it requires no lubrication.

The purpose of this work was to develop a high speed flow visualization system which could be used to observe the behavior of the air flow in a steady flow cylinder head assembly. This type of experimental rig has been used by engineers for many years to evaluate valve discharge coefficients. This study is believed to be the first high speed flow visualization of the air flow in a system of this type. Particular emphasis was placed on the characterization of intake generated swirl and tumble motions within the cylinder. A 40 watt copper vapor laser was used to expose motion picture films at 5000 frames per second. The light scattering medium was phenolic microballoons. Based on the flow visualization results, selected LDV measurements were made to quantify the visual observations. A propylene glycol aerosol was used for seeding in the LDV experiments.

A combined experimental/analytical study was made of a 2.2ℓ production engine. The objective was to characterize the performance of the engine and the pressure wave dynamics in its manifolds, and to compare the data/predictions obtained using an engine simulation program. Description of the computer program is given, providing an overview of its capabilities and of the models it contains. The data was obtained at wide open throttle, at four engine speeds from 1600 rpm to 4800 rpm. The comparisons showed the ability of the simulation to predict the major features of the wave dynamics, including the amplitude, frequency and phasing of the waves, and their tuning and de-tuning at the various engine speeds.