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The development of a modern internal combustion engine can be characterized by three main trends: durability increase, emission reduction, and fuel economy improvement. Ring pack design addresses all of these issues. The ring behavior affects the blow-by past the ring pack, the oil film left on the cylinder liner, the friction force between the liner and the ring, and the wear of the ring and the cylinder liner. In order to predict these phenomena, the prediction of inter-ring gas flow and ring behavior, especially ring motion and ring twist about ring centroid, is needed. This paper presents the results of the modeling of 3-dimensional ring twist and its influence on ring performance and blow-by. The TWIST program includes a 3-dimensional beam model of a piston ring.

This paper reviews progress on turbulent jet ignition systems for otherwise standard spark ignition engines, with focus on small prechamber systems (≺3% of clearance volume) with auxiliary pre-chamber fueling. The review covers a range of systems including early designs such as those by Gussak and Oppenheim and more recent designs proposed by General Motors Corporation, FEV, Bosch and MAHLE Powertrain. A major advantage of jet ignition systems is that they enable very fast burn rates due to the ignition system producing multiple, distributed ignition sites, which consume the main charge rapidly and with minimal combustion variability. The locally distributed ignition sites allow for increased levels of dilution (lean burn/EGR) when compared to conventional spark ignition combustion. Dilution levels are comparable to those reported in recent homogeneous charge compression ignition (HCCI) systems.

Numerical simulations of lean Methanol combustion in a four-stroke internal combustion engine were conducted on a high-compression ratio engine. The engine had a removable integral injector ignition source insert that allowed changing the head dome volume, and the location of the spark plug relative to the fuel injector. It had two intake valves and two exhaust ports. The intake ports were designed so the airflow into the engine exhibited no tumble or swirl motions in the cylinder. Three different engine configurations were considered: One configuration had a flat head and piston, and the other two had a hemispherical combustion chamber in the cylinder head and a hemispherical bowl in the piston, with different volumes. The relative equivalence ratio (Lambda), injection timing and ignition timing were varied to determine the operating range for each configuration. Lambda (λ) values from 1.5 to 2.75 were considered.

A stratified charge research engine and test stand were designed and built for this work. The engine was designed to exhibit some of the desirable traits of both the premixed charge gasoline engine and modern diesel engine. This spark ignition engine is fueled by M100 (99.99% pure methanol), operates under high compression (19.3:1) and uses direct fuel injection to form a stratification of the fuel-air mixture in the cylinder. The beginning of the combustion event of the stratified mixture is triggered by spark plug discharge. The primary goal of this project was to evaluate the feasibility of using a removable integral injector ignition source insert, which allows a convenient method of changing the relative location of the fuel injector to the ignition source, as well as the compression ratio, squish height, and bowl volumes. This paper provides an explanation of the hardware included in the experimental setup of the engine and selection of the direct injector configuration.

A numerical study on the combustion of Methanol in a directly injected (DI) engine was conducted. The study considers the effect of the bowl-in-piston (BIP) geometry, swirl ratio (SR), and relative equivalence ratio (λ), on flame propagation and burn rate of Methanol in a 4-stroke engine. Ignition-assist in this engine was accomplished by a spark plug system. Numerical simulations of two different BIP geometries were considered. Combustion characteristics of Methanol under swirl and no-swirl conditions were investigated. In addition, the amount of injected fuel was varied in order to determine the effect of stoichiometry on combustion. Only the compression and expansion strokes were simulated. The results show that fuel-air mixing, combustion, and flame propagation was significantly enhanced when swirl was turned on. This resulted in a higher peak pressure in the cylinder, and more heat loss through the cylinder walls.

The paper is based on the premise that the sole purpose of combustion in piston engines is to generate pressure for pushing the expansion process away from the compression process (both expressed in terms of appropriate polytropes) to create a work producing cycle. This essential process, referred to as the dynamic stage of combustion, is carved out of the cycle and its salient properties deduced from the measured pressure profile, as a solution of an inverse problem: deduction of information on an action from its outcome. An analytical technique, construed for this purpose, is first presented and, then, applied to a direct injection, spark-ignition, methanol fueled four-stroke engine.

The sole purpose of combustion in a piston engine is to generate pressure in order to push the piston and produce work. Pressure diagnostics provides means to deduce data on the execution of the exothermic process of combustion in an engine cylinder from a measured pressure profile. Its task is that of an inverse problem: evaluation of the mechanism of a system from its measured output. The dynamic properties of the closed system in a piston engine are expressed in terms of a dynamic stage - the transition between the processes of compression and expansion. All the phenomena taking place in its course were analyzed in the predecessor of this paper, SAE 2002-01-0998. Here, on one hand, its concept is restricted to the purely dynamic effects, while on the other, the transformation of system components, taking place in the course of the exothermic chemical reaction to raise pressure, are taken into account by the exothermic stage.

Internal flow characteristics of a close coupled catalytic converter were examined by LDV measurements and high speed flow visualization. Although previous studies have been done on catalytic converters, they were conducted at steady state and using water flow seeded with a small quantity of tracer particles. The purpose of this study was to develop a better understanding of dynamic flows inside catalytic converters. The high speed flow visualization films and LDV results showed that areas of separation and circulation were present in the inlet region of the converter. Backflows into the neck of the converter were also observed. Each cylinder exhausted into a different region of the converter, with the front-middle region having the heaviest amount of flow. Large bursts of flow were created by each cylinder, while other regions of the inlet region showed backflows or very low flow rates. The midsection of the converter had a more uniform overall flow pattern.

Significant improvement of engine performance can be achieved by ushering in a micro-electronic system to control the execution of combustion - an exothermic process whose sole purpose is to generate pressure. Hence, the primary feedback for the controller is provided by a pressure transducer. The activators are piezo-electrically activated pintle valves of MEMS type. The task of the micro-electronic processor is to provide an accurate feed-forward signal for the actuators on the basis of the information obtained from the feedback signal, within a time interval between consecutive cycles. Furnished here for this purpose is an algorithm for an interface module between the pressure sensor and the governor. Concomitantly, the gains thus attainable in the reduction of fuel consumption and curtailment of pollutant formation are thereby assessed. The implementation of this method of approach is illustrated by application to a HCCI engine.

Currently, the heat transfer equation used in the rotary combustion engine CRCE) simulation model is taken from piston engine studies. These relations have been empirically developed by the experimental input coming from piston engines whose geometry differs considerably from that of the RCE. The objective of this work was to derive equations to estimate heat transfer coefficients in the combustion chamber of a RCE. This was accomplished by making detailed temperature and pressure measurements in a direct injection stratified charge (DISC) RCE under a range of conditions. For each specific measurement point, the local gas velocity was assumed equal to the local rotor tip speed. Local physical properties of the fluids were then calculated. Two types of correlation equations were derived and are described in this paper.

A computer program (referred to as UF-LRC-3D) was developed for studying the unsteady, three-dimensional flow field inside the combustion chambers of motored Wankel engines as a function of engine design and operating parameters. This paper presents the details of the governing equations and the numerical method used by UF-LRC-3D. Also presented are numerical solutions generated by UF-LRC-3D showing the velocity field inside a motored Wankel engine, the mixing of nonhomogeneous fuel-air mixtures that enter through the intake port, and the mixing that takes place when a gaseous fuel is injected into the combustion chamber during compression.

Increasing oil prices and more stringent emission laws require an improved efficiency from future automotive engines. Additionally, the competition of the automotive market demands longer service intervals and engine life-times. A potential to decrease the specific fuel consumption and improve specific volume is offered by means of increasing engine speed and maximum cylinder pressure. Hence, the mechanical stress on the tribological system including the piston, piston rings, cylinder liner, are increased and the reliability decreases. The objective of this research is the development of a mathematical model implemented in software, which can deliver a prediction of piston ring wear in internal combustion engines. The program has been applied to a top compression piston ring of a turbo charged Diesel engine at WOT operation conditions.

The flow inside a combustion engine is highly complex and varies significantly with small changes in the engine configuration. For a long time IC-engine researchers have tried to predict the major mean flow patterns inside close-to-production engine setups. During the last decades computational fluid dynamics (CFD) has significantly contributed to the engine development process. Hence, significant research has focussed on the comparison of modeled and measured flows in IC engines. However, according to the knowledge of the authors, this study is the first fully three-dimensional (3-D), modeling and measurement effort that has evaluated the vast majority of the displacement volume by using an identical engine geometry. With improved, non-intrusive, 3-D velocity measurement technology, the vast majority of the cylinder displacement was explored and compared with Star-CD modeling results at the same locations.

Improvements in engine combustion depend on a thorough understanding of the actual in-cylinder flows. This study is thought to be the first fully three-dimensional (3-D) LDV measurement effort that evaluated the vast majority of the displacement volume under a variation of speed, load, and stroke during the intake and compression strokes. The intake port geometry was not changed during the course of the study. Most of the engine setups studied showed similar in-cylinder velocity patterns. The well developed tumble motion exhibited only marginal changes under the different speed, load, and throttle conditions with one exception: at idle condition, the tumble motion broke down into two equally strong downward flows along the cylinder liner. For all the other setups a robust tumble motion, which was distributed throughout the displacement volume prevailed until the end of measurement, sustaining significant amounts of ttumble motion until late in compression.

The flow inside of an internal combustion engine is highly complex and varies greatly among different engine types. For a long time IC engine researchers have tried to classify the major mean flow patterns and turbulence characteristics using different measurement techniques. During the last three decades tumble and swirl numbers have gained increasing popularity in mean flow quantification while turbulent kinetic energy has been used for the measurement of turbulence in the cylinder. In this paper, simultaneous 3-D LDV measurements of the in-cylinder flows of the three different engines are summarized for the quantification of the flow characteristics. The ensemble averaged velocity, tumble and swirl motions, and turbulence kinetic energy during the intake and compression strokes were examined from the measured velocity data (approximately 2,000 points for each case) by the 3-D LDV system.