Refine Your Search

Topic

Author

Search Results

Journal Article

Transmission Electron Microscopy of Soot Particles Directly Sampled in Diesel Spray Flame - A Comparison between US#2 and Biodiesel Soot

2012-04-16
2012-01-0695
For a better understanding of soot formation and oxidation processes in conventional diesel and biodiesel spray flames, the morphology, microstructure and sizes of soot particles directly sampled in spray flames fuelled with US#2 diesel and soy-methyl ester were investigated using transmission electron microscopy (TEM). The soot samples were taken at 50mm from the injector nozzle, which corresponds to the peak soot location in the spray flames. The spray flames were generated in a constant-volume combustion chamber under a diesel-like high pressure and high temperature condition (6.7MPa, 1000K). Direct sampling permits a more direct assessment of soot as it is formed and oxidized in the flame, as opposed to exhaust PM measurements. Density of sampled soot particles, diameter of primary particles, size (gyration radius) and compactness (fractal dimension) of soot aggregates were analyzed and compared. No analysis of the soot micro-structure was made.
Technical Paper

A New Method for Engine Low Power Detection in Trucks

1997-11-17
973181
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

A Mean Value Based Sizing and Simulation Model of a Hydrogen Fueled Spark-Ignition Internal Combustion Engine

2007-09-17
2007-01-3789
A mean value based sizing and simulation model has been developed for use in the conceptual design and sizing of hydrogen fueled spark-ignition internal combustion engines (HICE) in the aerospace industry, here ‘mean value’ includes mean effective pressure (MEP), mean piston speed, mean specific power, etc. This model is developed since there is currently no such model readily available for this purpose. When sizing the HICE, statistical data and common practice for gasoline internal combustion engines (GICE) are used to obtain preliminary sizes of the HICE, such as total cylinder volume, bore and stroke; to capture the effect of low volumetric efficiency, the preliminary results are adjusted by a volumetric correction factor until the cycle parameters of HICE are reasonable. A non-dimensional combustion model with hydrogen as fuel is incorporated with existing GICE methods. With this combustion model, the high combustion temperature and high combustion pressure are captured.
Technical Paper

The Cummins Signature 600 Heavy-Duty Diesel Engine

1998-02-23
981035
Design and development of the Cummins Signature 600, a new high horsepower dual overhead cam truck diesel engine, has been completed. The Signature 600 product system includes an all-new engine, controls, fuel system, and business information systems. During product definition, particular emphasis was placed on target markets, customer input to design, engineering and manufacturing processes, concurrent engineering and extensive mechanical and thermal analyses. Cummins Signature 600 fulfills the needs of Owner-Operator and Premium Fleet linehaul trucking businesses.
Technical Paper

Disc Brake Rotor Squeal Suppression Using Dither Control

2001-04-30
2001-01-1605
“Dither” control recently has been experimentally demonstrated to be an effective means to suppress and prevent rotor mode disc brake squeal. Dither control employs a control effort at a frequency higher, oftentimes significantly higher, than the disturbance to be controlled. The control actuator used for the work presented in this paper is a piezoelectric stack actuator located within the piston of a floating caliper brake. The actuator is driven in open-loop control at a frequency greater than the squeal frequency. This actuator configuration and drive signal produces a small fluctuation about the mean clamping force of the brake. The control exhibits a threshold behavior, where complete suppression of brake squeal is achieved once the control effort exceeds a threshold value. This paper examines the dependency of the threshold effort upon the frequency of the dither control signal, applied to the suppression of a 5.6 kHz rotor squeal mode.
Technical Paper

MODELING AND CONTROL OF TRANSIENT ENGINE CONDITIONS

2001-10-01
2001-01-3231
In gasoline direct injection engines, fuel is injected into the port walls and the valve. During the engine startup cycle, the temperature of these parts is not adequate to evaporate all the fuel that impacts the walls. As a result, a fraction of the injected fuel does not contribute to the combustion cycle. This fraction forms fuel puddles (wall-wetting) and a portion of it passes to the crankcase. The efficiency of the engine during the startup cycle is decreased and hydrocarbon emissions increased. It is obvious that a control strategy is necessary to minimize the effects of this transient performance of the engine. This paper investigates a modeling framework for the valve, and simulation results validate model performance when compared to available experimental data. The simulation studies lead to a conceptual control design, which is briefly outlined.
Technical Paper

Pressure Field Evolution on Rotor Blades at High Advance Ratio

2016-09-20
2016-01-2010
The design of advanced rotorcraft requires knowledge of the flowfield and loads on the rotor blade at extreme advance ratios (ratios of the forward flight speed to rotor tip speed). In this domain, strong vortices form below the rotor, and their evolution has a sharp influence on the aero-dynamics loads experienced by the rotor, particularly the loads experienced at pitch links. To understand the load distribution, the surface pressure distribution must be captured. This has posed a severe problem in wind tunnel experiments. In our experiments, a 2-bladed teetering rotor with collective and cyclic pitch controls is used in a low speed subsonic wind tunnel in reverse flow. Stereoscopic particle image velocimetry is used to measure the three component spatial velocity field. Measurement accuracy is now adequate for velocity data, and can be converted to pressure both at and away from the blade surface.
Technical Paper

Transmission Electron Microscopy of Soot Particles sampled directly from a Biodiesel Spray Flame

2011-08-30
2011-01-2046
For better understanding of soot formation and oxidation processes in a biodiesel spray flame, the morphology, microstructure and sizes of soot particles directly sampled in a spray flame fuelled with soy-methyl ester were investigated using transmission electron microscopy (TEM). The soot samples were taken at different axial locations in the spray flame, 40, 50 and 70 mm from injector nozzle, which correspond to soot formation, peak, and oxidation zones, respectively. The biodiesel spray flame was generated in a constant-volume combustion chamber under a diesel-like high pressure and temperature condition (6.7 MPa, 1000K). Density, diameter of primary particles and radius of gyration of soot aggregates reached a peak at 50 mm from the injector nozzle and was lower or smaller in the formation or oxidation zones of the spray.
Technical Paper

Experimental and Analytical Studies of Cylinder Head Cooling

1993-04-01
931122
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

The Piston Ring Shape and Its Effects on Engine Performance

1996-02-01
960052
The paper presents the latest research results on the piston ring free shape. A new free shape measurement method with optical gauging was developed. Three numerical models to compute the contact force distribution of piston ring were developed using finite element analysis (FEA). These numerical methods have been compared each other, and validated with the experimental results of ring deformation in a ring gage. The contact force distribution of a piston ring at working condition was also studied. It consists of the ring thermal boundary conditions (RTBC) validation, 3-D FEA thermal analysis and thermal contact force computation based on validated wire-cable element model. The RTBC for heavy duty diesel engine has been validated for the first time using a CUMMINS L10 engine test. Three different free shapes have been tested. The wear band measurements of tested rings all show tremendous improvements over the standard top ring.
Technical Paper

New Piston Telemetry Applied to Spherical Joint Piston Development

1996-02-01
960056
A new telemetry system has been developed for temperature or strain measurements on a spherical joint piston. The system includes a piston mounted signal multiplexer and transmitter. A patented, piston mounted power generator operates in conjunction witii a modified cylinder liner. The telemetry system is robust, having high inertia load capability and high environmental temperature operating capability. The telemetry system was installed and operated on an engine motoring test rig. Temperature signals were transmitted at engine speeds from 400 rpm to 2100 rpm. Over 100 hours of high engine speed testing with oil sump temperatures up to 122°C were completed.
Technical Paper

Experimental Results on the Effect of Piston Surface Roughness and Porosity on Diesel Engine Combustion

1996-02-01
960036
Measurements have been made to determine the effect of piston crown surface properties on combustion. Back-to-back engine tests were conducted to compare surface modified pistons to a production piston. Each modified piston was found to prolong combustion duration. Porous coatings and a non porous, roughened piston were observed to increase fuel consumption. Increase in fuel consumption was determined to be the result of increased heat release duration. The data show surface roughness alone affects the duration of heat release. The shift in magnitude of the centroid of heat release was similar to the shift observed in insulated engine experiments.
Technical Paper

Experimental Measurements on the Effect of Insulated Pistons on Engine Performance and Heat Transfer

1996-02-01
960317
Data have been gathered to compare the performance of steel crown pistons coated with yttria stabilized zirconia or mullite to an uncoated piston. The effect of coated pistons on in-cylinder heat transfer was determined from curves of ISFC versus centroid of heat release. Error analysis of the measurements showed uncertainty of ± 3% in ISFC and ± 2 crank angle degrees in the centroid of heat release could be expected for the data. Particulate emissions increased at advanced injection timings with the mullite coated piston while the zirconia coated piston showed an increase in particulate and NOx at advanced timings.
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

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

1981-10-01
811234
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

Vechicle Testing of Cummins Turbocompound Diesel Engine

1981-02-01
810073
Two turbocompound diesel engines were assembled and dynamometer tested in preparation for vehicle tests. Both engines met the 1980 California gaseous emission requirement and achieved a minimum BSFC of .313 lb/bhp-hr and a BSFC at rated conditions of .323 lb/bhp-hr. These engines were then installed in Class VIII heavy-duty vehicles to determine the fuel consumption and performance characteristics. Fuel consumption testing showed a 14.8% improvement for the turbocompound engine in comparison to a production NTC-400 used as a baseline. The turbocompound engine also achieved lower noise levels, improved drive-ability, improved gradeability, and moderately increased engine retardation. The second turbocompound engine was placed in commercial service and accumulated 50,000 miles on a cross-country route without malfunction. Tank mileage revealed a 15.92% improvement over a production NTCC-400 which was operating on the same route.
Technical Paper

A Preliminary Model for the Formation of Nitric Oxide in Direct Injection Diesel Engines and Its Application in Parametric Studies

1973-02-01
730083
A semiempirical, mathematical model describing the formation of nitric oxide in direct-injection diesel engines is derived. The model is used in conjunction with injection and thermodynamic cycle simulation programs. This approach enables prediction of nitric oxide emissions from design dimensions and operating parameters only, without the use of experimental data. Predicted results are compared with experiments for typical naturally aspirated and turbocharged engines. The accuracy of prediction is very good except under light-load naturally aspirated conditions. The model is used in an extensive parametric study, together with experimental verification. The agreement between prediction and experiments is excellent, except under conditions of excessive smoke or of high swirl.
Technical Paper

Design Factors That Affect Diesel Emissions

1971-02-01
710484
Although diesels, as a group, are a relatively small source of air pollutants, emissions standards which limit emissions from diesels have been adopted by California and the federal government. Test procedures and instrumentation for measuring diesel emissions have been developed, and an understanding of how engine design parameters affect emissions is evolving. Smoke and carbon monoxide are primarily functions of fuel-air ratio. Smoke is also affected by injection timing, air motion, and fuel spray characteristics. Hydrocarbon emissions are most affected by details of injector design and matching of the spray geometry with the combustion chamber shape. Nitric oxide emissions are controlled by local oxygen availability in regions of high temperature and residence time at the high temperature.
Technical Paper

Design Aspects of Low-Noise Diesel Engines

1973-02-01
730246
Methods of reducing the noise level of a diesel engine include the suppression of the major modes of block vibration and treatment of the external surfaces. Design methods enable the frequencies and noise levels of these modes to be calculated for a conventionally designed engine. The important modes of vibration, the noise signature and the effect of block modifications of a standard production V-8 engine were found by experiments. These provided the basis for the design of an experimental low-noise engine. Design features include a suffer block, removal of the bottom part of the crankcase skirt, the addition of a single bearing beam, and the use of isolated panels and damped surfaces. The noise reduction obtained was 9 dBA. Most of this is due to the use of isolated and damped nonload carrying surfaces.
Technical Paper

Diesel Engine Noise Reduction Hardware for Vehicle Noise Control

1973-02-01
730681
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.
X