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Technical Paper

Exhaust Characteristics of the Automotive Diesel

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.
Technical Paper

Combination Diesel Engine - Air Compressor - “The Dual Diesel”

Until recently, dry cargo has been unloaded from trucks by use of compressed air. By making the automotive engine act partly as an air compressor during the unloading operation, the auxiliary air compressor mounted on the tractor frame can be eliminated. This paper, in describing the dual diesel, discusses operating characteristics, cycle analysis, and operational problems.
Technical Paper

Cummins Technical Center

This paper presents the design philosophy and the technical capabilities of a new technical center built by Cummins Engine Co. The center was built primarily for development of diesel and similar engines, but also has broad capability for development of a variety of advanced power systems. The facility includes 88 instrumented test cells for testing power units up to 2000 hp under a complete range of environmental and special test conditions. Additional research laboratories support development activity and perform advanced studies in analytical techniques, materials development, and basic engine mechanisms.
Technical Paper

Comparison of Measured and Theoretical Inter-Ring Gas Pressure on a Diesel Engine

Inter-ring gas pressure and piston ring motion are considered important for the control of oil consumption, particulate emissions, and reduced friction. For this reason, inter-ring gas pressure was measured on a diesel engine. Two different ring pack configurations were tested (positive and negative twist second rings). A significant difference in measured inter-ring pressure was observed. The measurements were compared to the predictions of a cylinder kit model with favorable results. Predictions showed that the observed difference between measured inter-ring pressures is caused by a significant difference in ring motion. The reasons for these differences are explained in this paper.
Technical Paper

A New Method for Engine Low Power Detection in Trucks

A new method for detecting the low power conditions on electronically-controlled diesel engines used in on-road vehicles has been developed. The advantage of this method is that it uses readily available diagnostic tools and engine installed sensors with no necessity for a dynamometer test. Without removing the engine, it gives an estimate of the real engine power which is accurate to 5%.
Technical Paper

Cummins Light Truck Diesel Engine Progress Report, 2000

The Automotive Market in the United States is moving in the direction of more Light Trucks and fewer Small Cars. The customers for these vehicles have not changed, only their purchase decisions. Cummins has studied the requirements of this emerging market. Design and development of an engine system that will meet these customer needs has started. The engine system is a difficult one, since the combined requirements of a very fuel-efficient commercial diesel, and the performance and sociability requirements of a gasoline engine are needed. Results of early testing are presented which show that the diesel is possibly a good solution.
Technical Paper

Tribological Investigations for an Insulated Diesel Engine

A Minimum Cooled Engine (MCE) has been successfully run for 250 hours at rated condition of 298 kW and 1900 rpm. This engine was all metallic without any coolant in the block and lower part of the heads. Ring/liner/lubricant system and thermal loading on the liner at top ring reversal (TRR) as well as on the piston are presented and discussed. Ring/liner wear is given as well as oil consumption and blow-by data during the endurance run. Another engine build with a different top ring coating and several lubricants suggested that a 1500 hours endurance run of MCE is achievable. Rig test data for screening ring materials and synthetic lubricants necessary for a successful operation of a so-called Adiabatic Engine with the ring/ceramic liner (SiN) interface temperature up to 650°C are presented and discussed.
Technical Paper

A Numerical Study of the Transient Evaporating Spray Mixing Process in the Diesel Environment

Some results of a systematic study of the effects of fuel and chamber gas properties on the transient evaporating spray mixing process are presented. The study uses an existing two-dimensional stochastic thick spray model. The results show that the combustion process in typical heavy duty, quiescent, DI diesel engines can be mixing limited rather than vaporization limited. In addition, the results show that the mixing process of a transient evaporating spray is characterized by the combined effects of fuel evaporation and its turbulent mixing with the surrounding air. In general, increasing the evaporation rate alone does not necessarily increase the fuel-air mixing rate. Furthermore, two dimensionless parameters have been used to quantify the relative effects of fuel and chamber gas properties on the transient spray evaporation process. Finally, through detailed comparisons between spray and gas jet results, the transient evaporating spray mixing process is better understood.
Technical Paper

Effects of Injection Timing and Exhaust Gas Recirculation on Emissions from a D.I. Diesel Engine

Some results of a systematic study on the effects of injection timing retard and exhaust gas recirculation on emissions from a D.I. diesel engine are presented. The factors investigated include engine speed, fuel rate, injection timing, injection pressure, intake charge oxygen concentration, and type of diluent. The detailed mechanisms governing the formation and control of nitric oxide are studied analytically, using a previously developed diesel combustion model based on transient fuel-air mixing and Zeldovich nitric oxide reaction mechanisms. The results show that exhaust gas recirculation and injection timing retard are both effective in reducing nitric oxide emissions at the expense of increasing smoke. The reduction of nitric oxide with exhaust gas recirculation and injection timing retard is mainly related to the decrease of local temperature and local atomic oxygen concentration.
Technical Paper

Experimental and Analytical Studies of Cylinder Head Cooling

Previous work on the cooling jackets of the Cummins L10 engine revealed flow separation, and low coolant velocities in several critical regions of the cylinder head. The current study involved the use of detailed cooling jacket temperature measurements, and finite element heat transfer analysis to attempt the identification of regions of pure convection, nucleate boiling, and film boiling. Although difficult to detect with certainty, both the measurements and analysis pointed strongly to the presence of nucleate boiling in several regions. Little or no evidence of film boiling was seen, even under very high operating loads. It was thus concluded that the regions of seemingly inadequate coolant flow remained quite effective in controlling cylinder head temperatures. The Cummins L10 upon which this study has focused is an in-line six cylinder, four-stroke direct injection diesel engine, with a displacement of 10 liters.
Technical Paper

Test Cell Simulation of the Driveby Noise Test

Diesel engine manufacturers have traditionally done most engine noise development work under steady: state operating conditions. However, truck driveby noise tests are acceleration tests, and engines exhibit different noise behavior under accelerating conditions. Acceleration noise can be affected by engine performance parameters which may have no influence on steady state noise levels. In this study, a test cell simulation of the truck driveby procedure has been developed and evaluated. Test cell simulation and truck driveby results are compared for a naturally-aspirated and a turbocharged engine. This simulation procedure has been shown to predict reliably results measured in vehicles. As a result, the simulation can be used to evaluate engine modifications during the development process without requiring a vehicle installation.
Technical Paper

An Evaluation of the Lucas Combustion Noise Meter on Cummins ‘B’ Series Engines

Lucas Industries Noise Centre has introduced a combustion noise meter which is designed to predict the contribution of the combustion process to overall diesel engine noise. The performance of the meter is evaluated using Cummins B series engines in naturally-aspirated and turbocharged form. Combustion noise levels predicted by the meter are compared to levels determined using traditional techniques. The effects of several engine operating parameters on combustion noise are investigated under both steady state and accelerating conditions. The meter reliably predicts changes in combustion noise levels, and is a useful tool for performance development engineers. Combustion noise is shown to be related to the maximum rate of pressure rise at the onset of combustion, but combustion noise is not reliably related to maximum cylinder pressures.
Technical Paper

Combustion Chamber Component Analysis for Advanced Heavy Duty Diesel Engines

Detailed thermal analysis was conducted on several advanced cylinder head, liner, and piston concepts, for low heat rejection diesel engines. The analysis was used to define an optimized engine configuration. Results pointed to the strategic use of oil cooling and insulation in the cylinder head, an oil cooled cylinder liner, and an insulated piston, with separate insulation behind the compression rings. Such a configuration reduced in-cylinder heat rejection by 30 percent, while durability would be expected to be maintained or improved from today's production levels.
Technical Paper

Testing Procedures for Introduction of Silicon Carbide and Carbon Water Pump Seal Faces into Heavy Duty Diesel Service

Testing procedures to evaluate new coolant pump seal face materials and new coolant pump seal designs were evaluated. Rig testing of materials and seals followed by engine dynamometer testing enabled changes in the seal materials or design to be validated prior to field testing and limited production. These procedures were used to test and implement a coolant pump seal face material change to silicon carbide versus carbon. The change resulted in higher reliability for the coolant pump seal and reduced warranty cost for the engine.
Technical Paper

The Influence of Bowl Offset on Air motion in a Direct Injection Diesel Engine

The influence of bowl offset on motored mean flow and turbulence in a direct injection diesel engine has been examined with the aid of a multi-dimensional flow code. Results are presented for three piston geometries. The bowl geometry of each piston was the same, while the offset between the bowl and the cylinder axis was varied from 0.0 to 9.6% of the bore. The swirl ratio at intake valve closing was also varied from 2.60 to 4.27. It was found that the angular momentum of the air at TDC was decreased by less than 8% when the bowl was offset. Nevertheless, the mean (squish and swirl) flows were strongly affected by the offset. In addition, the distribution of turbulent kinetic energy (predicted by the k-e model) was modified. Moderate increases (10% or less) in mass averaged turbulence intensity at TDC with offset were observed. However, the TDC turbulent diffusivity was changed less than 3% due to a slight decrease in turbulent length scale with increasing offset.
Technical Paper

The Effects of Emulsified Fuels and Water Induction on Diesel Combustion

Water was inducted with the intake air and injected emulsified with the fuel, in a conventional single cylinder D.I. diesel engine. The major effects of inducted water were an increase in ignition delay, and reduction in the oxides of nitrogen and smoke at a constant fuel/air ratio. When the water was emulsified with the fuel, the ignition delay increased so much that no benefits were obtained except for a reduction in smoke. The results are compared to a similar study on an engine with the “M” combustion system. The major differences between the results obtained with the two combustion systems are attributed to the differences in the ignition delay caused by the water addition.
Technical Paper

Cummins V504 and V555 Engines

The Cummins V504 and V555 engines were developed for construction, industrial, agricultural, marine and medium duty automotive market requirements of lightweight, compact diesel engines in the 185-240 hp range. The engine design and development objectives were to obtain high reliability and durability combined with good overall efficiency in a compact package size. These objectives were achieved by careful attention to design details, combustion system development and extensive laboratory and field evaluation.
Technical Paper

Diesel Engine Noise Reduction Hardware for Vehicle Noise Control

A range of noise reduction hardware is described for three production engine models, as well as the rationale for selecting noise reduction methods. Noise reductions up to 6 dB(A) were achieved with this hardware in the test cell. In many cases the modifications are more effective in vehicles. The success of the hardware in reducing overall vehicle noise is illustrated.
Technical Paper

Cooling Higher Horsepower Highway Diesel Engines

The increase in power-to-weight ratio that results from the use of higher-horsepower diesel engines in highway service prompted this study of engine cooling. This paper covers the results obtained in testing different power-to-weight ratios on grades from sea level to over 11,000 ft and compares these results with those obtained from chassis and towing dynamometer cooling trials.
Technical Paper

Diesel Engine Component Design Using the Finite Element Method and Interactive Graphics

An inexpensive, flexible and convenient finite element analysis system can be implemented with limited capital and resources. A system of this nature can be a functional tool of the designer and stress analyst for the analysis of many types of mechanical components. The finite element models generated by this system can approach a high degree of complexity with a small time investment compared to the time required to do this job without the aid of the system described.