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A one-dimensional analysis was performed to analyze a three-pass muffler with perforated tubes for Transmission Loss, using numerical decoupling approach. Effect of mean flow on transmission loss inside the muffler was studied. To account for the three-dimensional nature of acoustic waves at higher frequencies, a three dimensional finite element analysis was done using SYSNOISE. The Transmission loss results of the three-dimensional analysis were compared with those of one-dimensional analysis for no flow case and shown to agree reasonably for lower frequency range.

Since the early inception of the adiabatic diesel engine in 1974, marked progress has taken place as a result of research efforts performed all over the world. The use of ceramics for heat engines in production applications has been limited to date, but is growing. Ceramic use for production heat engine has included: combustion prechambers, turbochargers, exhaust port liners, top piston ring inserts, glow plugs, oxygen sensors; and additional high temperature friction and wear components. The potential advantages of an adiabatic engine vary greatly with specific application (i.e., commercial vs. military, stationary vs. vehicular, etc.), and thus, a better understanding of the strengths and weaknesses (and associated risks) of advanced adiabatic concepts with respect to materials, tribology, cost, and payoff must be obtained.

The high temperature tribology issue for uncooled Low Heat Rejection (LHR) diesel engines where the cylinder liner piston ring interface exceeds temperatures of 225°C to 250°C has existed for decades. It is a problem that has persistently prohibited advances in non-watercooled LHR engine development. Though the problem is not specific to non-watercooled LHR diesel engines, it is the topic of this research study for the past two and one half years. In the late 1970s and throughout the 1980s, a tremendous amount of research had been placed upon the development of the LHR diesel engine. LHR engine finite element design and cycle simulation models had been generated. Many of these projected the cylinder liner piston ring top ring reversal (TRR) temperature to exceed 540°C[1]. In order for the LHR diesel to succeed, a tribological solution for these high TRR temperatures had to be developed.

The global flow characteristics such as mean velocity, turbulence intensity and scales of turbulence have been measured in a swirl combustion chamber of a Compression Ignition engine using a constant temperature hot-wire anemometer. The experiments were conducted at 400 rpm under motoring (non-firing) conditions. Ensemble averaging procedure was adopted to calculate the mean velocity and turbulence intensity after comparing the merits and demerits of this method with the Individual Cycle Mean method and the Frequency Separation method. The experimental results indicate that the mean velocity and turbulence intensity show significant spatial and temporal variations in the swirl chamber. These variations are observed to be maximum from 60 deg. bTDC to TDC of compression. The values of mean velocity at chamber periphery are found to be higher than the values near the chamber axis.

The two newest internal combustion engine technologies which have demonstrated the most promise in the last 25 years are the direct-injection stratified-charge (DISC) rotary engine [1] and the adiabatic diesel engine [2]. The (DISC) engine is particularly attractive for aviation applications [3] because of its light weight, multi-fuel capability and potential for low fuel consumption. However, one disadvantage with the DISC engine is the weight and size of the liquid cooling system. NASA Lewis Research Center has supported a technology enablement program to advance the DISC rotary engine for general aviation applications and recognizes the importance of improvement in fuel consumption and reductions in the coolant system weight [4].

This paper investigates theoretically the effects of heat transfer characteristics, such as crank-angle phasing and wall temperature swings, on the thermodynamic efficiency of an IC engine. The objective is to illustrate the fundamental physical basis of applying thin thermal barrier coatings to improve the performance of military and commercial IC engines. A simple model illustrates how the thermal impedance and thickness of coatings can be manipulated to control heat transfer and limit the high temperatures in engine components. A friction model is also included to estimate the overall improvement in engine efficiency by the proper selection of coating thickness and material.

Increasing the efficiency of engine auxiliary systems have become a challenge. Oil pump, identified for this study, is one such engine system which is used for lubrication of engine parts. To achieve higher efficiencies, there is a need for math-based analysis and design. This can be achieved by means of Computational Fluid Dynamics (CFD). The main aim of this paper is to simulate the flow through Gerotor Oil pump using Computational Fluid Dynamics. A 3D model of the entire flow domain is created and meshed in preprocessor GAMBIT. The mesh for various pressure outlet conditions is exported to FLUENT solver for analysis. The predicted results are validated with the experimental results. The comparison shows that the CFD predictions are in good agreement with experimental results. In particular, such a simulation offers a scope for visualizing the flow through the Gerotor oil pump.

The trend toward lighter vehicles for improved performance has recently introduced the use of aluminum and plastic materials for vehicle bodies and drive trains. In particular, the aluminum alloy block for engine application is certain to reappear. The soft aluminum cylinder liner will require additional treatment before acceptance. Three possible approaches appear to solve the aluminum cylinder liner dilemma. These approaches are: 1. Use of high silicon aluminum such as the 390 aluminum. 2. Insert or cast steel liners into the aluminum engine block. 3. Ceramic coat the low cost standard aluminum engine block. Each has known advantages and disadvantages. It is the purpose of this paper to present the merits of Option 3, the ceramic coated aluminum cylinder bore from the standpoint of low weight, cost, and tribological effectiveness. The advantages of approaches (1) and (2) are obvious. High temperature after treatment of the ceramic engine components is not required.

Thermal barrier coatings are becoming increasingly important in providing thermal insulation for heat engine components. Thermal insulation reduces in-cylinder heat transfer from the engine combustion chamber as well as reducing component structural temperatures. Containment of heat also contributes to increased in-cylinder work and offers higher exhaust temperatures for energy recovery. Lower component structural temperatures will result in greater durability. Advanced ceramic composite coatings also offer the unique properties that can provide reductions in friction and wear. Test results and analysis to evaluate the performance benefits of thin thermal barrier coated components in a single cylinder diesel engine are presented.

This paper describes the progress on the Cummins-TARADCOM adiabatic turbocompound diesel engine development program. An adiabatic diesel engine system adaptable to the use of high performance ceramics which hopefully will enable higher operating temperatures, reduced heat loss, and turbo-charged exhaust energy recovery is presented. The engine operating environments as well as the thermal and mechanical loadings of the critical engine components are covered. Design criteria are presented and techniques leading to its fulfillment are shown. The present shortcomings of the high performance ceramic design in terms of meeting reliability and insulation targets are discussed, and the needs for composite designs are shown. A ceramic design methodology for an insulated engine component is described and some of the test results are shown. Other possible future improvements such as the minimum friction-unlubricated engine through the use of ceramics are also described.

Of late direct injection engines are replacing carburetted and port injected engines due to their high thermal efficiency and fuel economy. One of the reasons for the increased fuel economy is the ultra lean mixture with which the engine operates under low loads. Under the low load conditions, the air fuel ratio of the mixture near the spark plug is close to stoichiometric values while the overall mixture is lean, which is called stratified mixture. In order to achieve this, proper air motion during the late stages of compression is a must. Quality of the mixture depends on the time of injection as well as the type of fuel injector and mixture preparation strategy used. Engines employing air guided mixture preparation are considered as the second generation engines. For understanding the efficient mixture preparation method, three types of flow structures like base (low tumble), high tumble and inclined swirl are created inside the engine cylinder using shrouds on the intake valves.

The experimental emissions testing of a turbocharged six cylinder Caterpillar 3116 diesel engine converted to the Miller cycle operation was conducted. Delayed intake valve closing times were also investigated. Effects of intake valve closing time, injection time, and insulation of piston, head, and liner on the emission characteristics of the Miller cycle engine were experimentally verified. Superior performance and emission characteristic was achieved with a LHR insulated engine. Therefore, all emission and performance comparisons are made with LHR insulated standard engine with LHR insulated Miller cycle engine. Particularly, NOx, CO2, HC, smoke and BSFC data are obtained for comparison. Effect of increasing the intake boost pressure on emission was also studied. Poor emission characteristics of the Miller cycle engine are shown to improve with increased boost pressure. Performance of the insulated Miller cycle engine shows improvement in BSFC when compared to the base engine.

Evaluation of combustion parameters such as ignition delay and combustion duration are very important in the design and development of reciprocating diesel engines. So far, there is no established and straight, forward method for the estimation of these parameters. In this paper first the available methods have been reviewed. Limitations of the direct method have been discussed. Effect of some operating variables like compression ratio, speed, load and injection advance on the combustion parameters have been studied. An easy and reliable approach has been suggested for the determination of start and end of combustion for a direct injection diesel engine, minimizing the personal judgment. Procedure for calculating the ignition delay and combustion duration based on the experimental study has been highlighted for the proposed method.

The production of pollutants and an increasing need for pollution management are an inevitable concomitant of a society with a high standard of living. The automotive diesel engine is used more than any other type of engine for transporting freight over highways. Two kinds of pollution to be considered with regard to the diesel engine are the dark exhaust smoke and odor, of which the public is quite cognizant, and the less obvious but possibly toxic carbon monoxide, oxides of nitrogen, unburned hydrocarbons, and trace compounds of other toxic materials. This paper discusses sampling, measurement techniques, and established standards for exhaust smoke and odor. Examination of diesel exhaust shows it to be less offensive in terms of harmful effects than the invisible exhaust from other types of engines. The major problem is exhaust color and odor.

The objective of present study is to predict and analyze the flow through the Carburettor for two different throttle opening conditions. The studies have been carried out by Computational Fluid Dynamics (CFD) software and the prediction has been validated with experimental data. Three dimensional geometrical models of two different throttle positions namely 50% opening and wide open throttle (100% throttle opening) were created using the commercially available software. The mesh was generated using the Tet-hybrid scheme which includes primarily of tetrahedral mesh elements but may also include hexahedral, pyramidal and wedge elements. The pressure boundary conditions are used to define the fluid pressure at the inlet and outlet of the carburettor. The steady state flow field analysis inside a carburettor has been simulated using the Multiphase mixture model and Langrangian Discrete phase model.

Aldehyde formation and emissions from alcohol fueled engines are studied and presented in this paper. Several chemical kinetic models on the mechanism leading to aldehyde formation have been examined to explore the appropriate control methods to reduce exhaust aldehyde emissions. Control of aldehydes in exhaust emissions by suitable alteration of engine operating parameters, by in cylinder treatment with additives like aniline and water, by external treatment like airpreheating, secondary air injection cooling water rate and exhaust treatment are examined. The concept of surface ignition for alcohol fuels is briefly presented as a long range objective for using alcohols with minimal aldehyde emissions.

In the conventional scavenging process of the two-stroke spark ignition engines, a part of the fresh mixture leaves the cylinder along with the burnt products and contributes heavily towards the hydro-carbon emission in the engine exhaust with high S. F. C. In this investigation an attempt is made to reduce the fresh mixture loss to the exhaust line during the scavenging process, by incorporating reed valves at the transfer ducts. It is observed that this approach reduces the fuel consumption to the engine without any power loss and decreases the hydro-carbon content in the engine exhaust.

High-pressure fuel injection combustion is being applied as an approach to increase the power density of diesel engines. The high-pressure injection enables higher air utilization and thus improved smoke free low air-fuel ratio combustion is obtained. It also greatly increases the injection rate and reduces combustion duration that permits timing retard for lower peak cylinder pressure and improved emissions without a loss in fuel consumption. Optimization of these injection parameters offers increased power density opportunities. The lower air-fuel ratio is also conducive to simpler air-handling and lower pressure ratio turbocharger requirements. This paper includes laboratory data demonstrating a 26 percent increase in power density by optimizing these parameters with injection pressures to 200 mPa.

This paper deals with the analysis of heat release characteristics of an insulated turbocharged, six cylinder, DI contemporary diesel engine. The engine is fully insulated with thin thermal barrier coatings. Effect of insulation on the heat release was experimentally verified. Tests were carried over a range of engine speeds at 100%, 93%, 75% and 50% of rated torque. Fuel injection system was instrumented to obtain injection pressure characteristics. The study shows that rate of heat release, particularly in the major portion of the combustion, is higher for the insulated engine. Improvement in heat release and performance are primarily attributed to reduction in heat transfer loss due to the thin thermal barrier coating. Injection pressure at the rated speed and torque was found to be 138 MPa and there was no degradation of combustion process in the insulated engine. Improvements in BSFC at 93% load are 3.25% and 6% at 1600 and 2600 RPM, respectively.

Thin thermal barrier ceramic coatings were applied to a standard production direct injection diesel engine. The resultant fuel economy when compared to the standard metallic engine at full load and speed (2600) was 6% better and 3.5% better at 1600 RPM. Most coated diesel engines todate have not shown significant fuel economy one way or the other. Why are the results more positive in this particular case? The reasons were late injection timing, high injection pressure with high injection rates to provide superior heat release rates with resultant lower fuel consumption. The recent introduction of the high injection pressure fuel injection system makes it possible to have these desirable heat release rates at the premixed combustion period. Of course the same injection characteristics were applied to the standard and the thin thermal barrier coating case. The thin thermal barrier coated engine displayed superior heat release rate.