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Technical Paper

Evaluation of Microalloyed Steel for Articulated Piston Applications in Heavy Duty Diesel Engines

2000-03-06
2000-01-1232
AISI-4140H steel has been used as articulated piston crown material in heavy-duty engines. With the driving force for reducing manufacturing cost, microalloyed steel (MAS) was identified as a low-cost material to replace 4140H steel. In order to determine the feasibility of using MAS to replace 4140H steel, a test program was initiated to fully evaluate the material properties of MAS and to compare them to those of the baseline 4140H steel. The physical and mechanical properties of both materials from room temperature to 550°C were evaluated. The effect of long term thermal exposure on the material properties was also studied. Some engine tests were also conducted to evaluate the performance of the articulated pistons made with both materials. The inherently lower strength of MAS as compared to 4140H steel, requires a total re-design of the piston for the utilization of MAS as a low-cost replacement material for 4140H steel.
Technical Paper

Visual Thermodynamics: Processes in Log(p)-Log(T) Space

1999-03-01
1999-01-0516
A new technique has been developed to allow engine performance engineers to visualize and communicate a wide range of thermodynamic issues and constraints in a single diagram. The technique, called Visual Thermodynamics, is the presentation of engine cycle data in logarithmic pressure and logarithmic temperature space, log(p)-log(T). Visual Thermodynamics is a thought organization and concept visualization tool. It is not intended to provide high-precision numerical results. The utility of the technique is in comparing engine concepts, assessing trends, identifying boundaries of operation and building a general understanding of engine system behavior. The technique provides a powerful mechanism for communicating engine thermodynamic issues to both technical and non-technical colleagues.
Technical Paper

Effect of Fuel Composition and Altitude on Regulated Emissions from a Lean-Burn, Closed Loop Controlled Natural Gas Engine

1997-05-01
971707
Natural gas presents several challenges to engine manufacturers for use as a heavy-duty, lean burn engine fuel. This is because natural gas can vary in composition and the variation is large enough to produce significant changes in the stoichiometry of the fuel and its octane number. Similarly, operation at high altitude can present challenges. The most significant effect of altitude is lower barometric pressure, typically 630 mm Hg at 1600 m compared to a sea level value of 760 mm. This can lower turbocharger boost at low speeds leading to mixtures richer than desired. The purpose of this test program was to determine the effect of natural gas composition and altitude on regulated emissions and performance of a Cummins B5.9G engine. The engine is a lean-burn, closed loop control, spark ignited, dedicated natural gas engine. For fuel composition testing the engine was operating at approximately 1600 m (5,280 ft) above sea level.
Technical Paper

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

1996-10-01
961909
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

Cavitation Intensity Measurements for Internal Combustion Engines

1996-02-01
960884
Recent engine design trends towards increasing power, reducing weight, advancing of injection timing and increasing of injection rate and pressure could result in increased incidence of liner pitting. Liner pitting due to coolant cavitation is a complex function of many engine design parameters and operating conditions as described in reference [1]*. Traditionally, liner cavitation problems were not detected early in the development cycle. Traditional liner vibration and coolant pressure measurements in conjunction with a numerous amount of expensive engine endurance tests were then needed to resolve cavitation problems. A method newly developed by the author and described in reference [2] for cavitation intensity measurements was successfully utilized to map out engine operating condition and develop limit curves. This method could also be applied in a non intrusive fashion.
Technical Paper

Real Time Captivation Detection Method

1996-02-01
960878
Cavitation corrosion is a very complex phenomenon that is governed by a formidable amount of factors and parameters. The phenomenon is a multi-disciplinary one which involves several aspects of physical sciences and engineering. This process is a slow progressive phenomenon with its detrimental effects being felt after severe damage has already occurred. A real time detection method for the severity of fluid cavitation and bubble collapse is described. The results are correlated to dynamic instantaneous pressure fluctuation measurements. The method is fast, reliable, and less restrictive of the sensing location. It has been tested and verified through a specially designed cavitation test rig and instrumentation setup. The method can be used for cavitation studies on ultrasonic bench rig tests and for cavitation measurements on running engines. The method was used to shed some light on characteristic cavitation differences between water and glycol which is used in engine coolants.
Technical Paper

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

1993-03-01
930585
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 Effect of Raising Specific Output of a Highly Rated DI Diesel Truck Engine on its Performance and Emissions

1989-02-01
890263
A study was undertaken to establish what happens to engine emissions, and to turbocharger and injection pressure requirements, as the specific output is raised. For any given engine package, increasing specific output increases injection pressures while reducing air/fuel ratios. Thus, if the highly rated engine must satisfy the same design constraints, then raising the engine operating torque by only 10% resulted in more than 30% increase in total particulates! However, the same emission levels may be maintained if increases in specific output are accompanied by changes to engine design so as to maintain the air-fuel mixing parameters, specifically air/fuel ratio and injection pressures, throughout the entire engine operating conditions.
Technical Paper

Test Cell Simulation of the Driveby Noise Test

1987-08-01
870967
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

1987-08-01
870952
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 Insulation Effect on the Performance of a Low Heat Rejection Cummins V-903 Engine

1986-03-01
860317
Cummins Engine Company is developing a low heat rejection 450 kW engine under contract for the US Army Tank & Automotive Command. This paper discusses progress made toward achieving the program goals of 6.6 kcal/kW-min brake specific heat rejection and 200 g/kW-hr brake specific fuel consumption. Methodology for measuring heat rejection on a low heat rejection engine is presented. Design improvements of the base engine are discussed along with their effect on improving fuel consumption. Performance test data is assessed in terms of the first law energy balance and cooling load distribution. The heat rejection data provides insights on the performance of insulating components and two cooling system designs. Diesel cycle simulations are compared to the test data and are used to predict the effect of ceramic insulation on engine heat rejection.
Technical Paper

Reduced Durability due to a Friction Modifier in Heavy Duty Diesel Lubricants

1985-04-01
851260
RAPID CORROSIVE WEAR OF COPPER ALLOYS caused by a friction reducing additive was encountered in field tests of experimental lubricants. This oil soluble molybdenum, sulphur, and phosphorous containing additive subsequently was used in several commercial heavy duty diesel lubricants although the additive manufacturer did not recommend it for such applications. Numerous engine failures occurred due to the aggressiveness of this additive toward copper. Standard laboratory engine test methods or standard bench test methods did not predict the severe field problem. A new laboratory engine test method has been shown to duplicate the field failures. Bench test methods to duplicate the field failures are discussed. The mode of failure is shown and described.
Technical Paper

Cummins/TACOM Adiabatic Englue Program

1985-02-25
850356
Joint development of the adiabatic engine by Cummins Engine Company and the U. S. Army began with a feasibility analysis ten years ago. The effort was initially driven by the expectation of substantial performance improvement, a reduction in cooling system size, and several additional benefits. Program emphasis turned quickly to experimentation with the goal of demonstrating the feasibility of the adiabatic engine in working hardware. Several significant achievements were realized as have been reported earlier. Further development of the adiabatic engine is expected to be more evolutionary, paced by available technology in the areas of materials and tribology. Analysis capability necessary for insulated engine development has been found to be inadequate. Additional effort has gone into the development and validation of insulated engine analysis tools, both for cycle simulation and structural modeling.
Technical Paper

Modeling of Transient Evaporating Spray Mixing Processes-Effect of Injection Characteristics

1984-02-01
840226
Some results of a systematic numerical study of the effects of injection characteristics on the transient evaporating spray mixing process in a diesel like environment are presented. The study uses an existing two-dimensional stochastic thick spray model. It was found that, for a fixed injection quantity, changes in the nozzle hole number, nozzle hole size, and injection duration changed significantly the evaporation and mixing processes of a transient evaporating spray. In particular, It is found that, for a fixed nozzle geometry, reduced injection duration is most effective in increasing the mixing rate. The results also show that the injection rate shape greatly influences the mixing process of a transient spray, especially during the injection period. After the end of injection, the global effect of injection rate shape can be characterized by the mass averaged injection pressure alone. The higher the mass averaged injection pressure, the faster the mixing rate.
Technical Paper

Tribological Investigations for an Insulated Diesel Engine

1983-02-01
830319
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

Performance and Regeneration Characteristics of a Cellular Ceramic Diesel Particulate Trap

1982-02-01
820272
Fundamental aspects of performance and regeneration of a porous ceramic particulate trap are described. Dimensionless correlations are given for pressure drop vs. flow conditions for clean and loaded traps. An empirical relationship between estimated particulate deposits and a loading parameter that distinguishes pressure drop changes due to flow variations from particulate accumulation is presented. Results indicate that trapping efficiencies exceed 90% under most conditions and pressure drop doubles when particulate accumulation occupies only 5% of the available void volume. Regeneration was achieved primarily by throttling the engine intake air. For various combinations of initial loading level, trap inlet temperature and oxygen concentration, it was found that regeneration rate peaked after 45 seconds from initiation.
Technical Paper

Wind Tunnel Investigation of the Effects of Installation Parameters on Truck Cooling System Performance

1976-02-01
760832
The effect of eight installation and component parameters on cooling system heat rejection and air flow were examined in detail in a wind tunnel facility. A quarter-replicate, two level factorial test plan was followed. Within the ranges of each parameter tested, the fan characteristics and the projection of fan into the shroud are highly significant parameters. The fan to radiator distance, the radiator characteristics, and the fan tip to shroud clearance are significant parameters. The fan to engine block distance and the type of shroud are not significant parameters.
Technical Paper

Cooling Higher Horsepower Highway Diesel Engines

1975-02-01
750131
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

Techniques of Structural Vibration Analysis Applied to Diesel Engine Noise Reduction

1975-02-01
750835
This paper presents several techniques used to define quantitatively the problem of excessive noise through engine structural vibration. These techniques include both operating engine tests and bench tests. In addition, analytical techniques are shown which give a better understanding of how the critical components within the engine cause this vibration. Through the use of analytical and experimental techniques, examples illustrate practical solutions for diesel engine noise reduction.
Technical Paper

Cummins K-Series Engines

1974-02-01
740036
New heavy-duty diesel engines of 6-, 8-, 12-, and 16-cyl rated 75 hp/cyl turbocharged and 100 hp/cyl turbocharged and aftercooled are being developed. Design and development objectives include maximizing engine durability/reliability and use of common parts in all engine models. Fuel consumption, smoke, exhaust gas emissions, and engine noise equal or better than the best current engines within engine configurations readily adaptable to current automotive and construction equipment are also prime considerations. Initial models of the engine series meet the design and development objectives.
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