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Technical Paper

LES and RNG Turbulence Modeling in DI Diesel Engines

2003-03-03
2003-01-1069
The one-equation subgrid scale model for the Large Eddy Simulation (LES) turbulence model has been compared to the popular k-ε RNG turbulence model in very different sized direct injection diesel engines. The cylinder diameters of these engines range between 111 and 200 mm. This has been an initial attempt to study the effect of LES in diesel engines without any modification to the combustion model being used in its Reynolds-averaged Navier-Stokes (RANS) form. Despite some deficiencies in the current LES model being used, it already gave much more structured flow field with approximately the same kind of accuracy in the cylinder pressure predictions than the k-ε RNG turbulence model.
Technical Paper

Observation of Transient Oil Consumption with In-Cylinder Variables

1996-10-01
961910
Only a limited understanding of the oil consumption mechanism appears to exist, especially oil consumption under transient engine operating conditions. This is probably due to the difficulty in engine instrumentation for measuring not only oil consumption, but also for measuring the associated in-cylinder variables. Because of this difficulty, a relatively large number of experiments and tests are often necessary for the development of each engine design in order to achieve the target oil consumption that meets the requirements for particulate emissions standards, oil economy, and engine reliability and durability. Increased understanding and logical approaches are believed to be necessary in developing the oil-consumption reduction technology that effectively and efficiently accomplishes the tasks of low oil-consumption engine development.
Technical Paper

Mixture Preparation Measurements

1995-02-01
950069
A technique was demonstrated that can quantify the state of mixture preparation during the critical periods of ignition and very early flame development in a “production” spark-ignited engine. To determine the degree of stratification and vaporization two fast-response hydrocarbon (HC) probes were placed in a specially adapted spark plug. Data from the HC analyzer was correlated with cylinder pressure data to relate changes in mixture preparation to classic engine measures, such as indicated mean effective pressure (IMEP) and ignition delay.
Technical Paper

A Heavy-Fueled Engine for Unmanned Aerial Vehicles

1995-02-01
950773
The growing usage of Unmanned Aerial Vehicles (UAVs) for aerial surveillance and reconnaissance in military applications calls for lightweight, reliable powerplants that burn heavy distillate fuels. While mass-produced engines exist that provide adequate power-to-weight ratio in the low power class needed for UAVs, they all use a spark-ignited combustion system that requires high octane fuels. Southwest Research Institute (SwRI) has embarked upon an internal research effort to design and demonstrate an engine that will meet the requirements of high power density, power output compatible with small unmanned aircraft, heavy-fuel combustion, reliable, durable construction, and producible design. This effort has culminated in the successful construction and operation of a demonstrator engine.
Technical Paper

Evaluation of High-Temperature Diesel Engine Liquid Lubricants

1995-10-01
952544
High-temperature lubricant (HTL) requirements for future U.S. Army ground vehicles were investigated. A single-cylinder diesel engine (SCE-903) was successfully modified to operate at increased cylinder liner temperatures and to serve as a tool for HTL evaluation. Oil D, one of six lubricants evaluated, completed 200 test hours at an average cylinder wall temperature of 247°C and an oil sump temperature of 166°C with only minor oil degradation. However, improved piston cleanliness is desired.
Technical Paper

Analysis of a Novel Two-Stroke Engine Scavenging Arrangement: The Neutron Engine

1995-09-01
952140
A unique two-stroke engine design is investigated in which fresh mixture is introduced into the cylinder through a valve in the piston crown, and exhausted through peripheral cylinder ports. The engine behaves as a free-piston engine through a portion of the cycle when the piston lifts off the valve seat. The fresh air jet rising along the cylinder centerline effectively displaces the burned gases with little mixing of the two streams. The concept was analyzed by a combination of dynamic cycle simulation and prediction of the in-cylinder flow characteristics by multidimensional modeling. The cycle simulation program considered the dynamics of the piston during its free motion as well as under the kinematic constraints of the crank system. A zero-dimensional thermodynamic model of the cylinder was used to predict cycle pressure and temperature, indicated power, fuel consumption, and flow in and out of the cylinder.
Technical Paper

Coal-Water-Slurry Autoignition in a High-Speed Detroit Diesel Engine

1994-10-01
941907
Autoignition of coal-water-slurry (CWS) fuel in a two-stroke engine operating at 1900 RPM has been achieved. A Pump-Line-Nozzle (PLN) injection system, delivering 400mm3/injection of CWS, was installed in one modified cylinder of a Detroit Diesel Corporation (DI)C) 8V-149TI engine, while the other seven cylinders remained configured for diesel fuel. Coal Combustion was sustained by maintaining high gas and surface temperatures with a combination of hot residual gases, warm inlet air admission, ceramic insulated components and increased compression ratio. The coal-fueled cylinder generated 85kW indicated power (80 percent of rated power), and lower NOx levels with a combustion efficiency of 99.2 percent.
Technical Paper

The Stratified Charge Glowplug Ignition (SCGI) Engine with Natural Gas Fuel

1991-09-01
911767
The objective was to demonstrate the feasibility of operating a natural gas two-stroke engine using glow plug ignition with very lean mixtures. Based on the results obtained, the term SCGI (stratified charge glow plug ignition) was coined to describe the engine. An JLO two-stroke diesel engine was converted first to a natural gas fueled spark-ignited engine for the baseline tests, and then to an SCGI engine. The SCGI engine used a gas operated valve in the cylinder head to admit the natural gas fuel, and a glow plug was used as a means to initiate the combustion. The engine was successfully run, but was found to be sensitive to various conditions such as the glow plug temperature. The engine would run very lean, to an overall equivalence ratio of 0.33, offering the potential of good fuel economy and low NOx emissions.
Technical Paper

A Single Cylinder Medium Speed Diesel Engine Research Facility

1988-08-01
881163
A Single Cylinder Medium Speed diesel engine research facility has been developed for investigating areas of current technical concern to the rail, marine and stationary power industries. The design and operation of this Single Cylinder Research Engine (SCRE) is described. The facility is centered around a Bombardier model 251-plus 11.0 L engine which is representative of four stroke multi-cylinder railroad, marine and small stationary powerplant engines. All engine support systems (air, cooling water, fuel oil and lubricating oil pumps) operate independent of the engine enabling a wide range of adjustments in flow, pressure and temperature. Current program areas for which this system is used include alternative fuels evaluation, combustion analyses, fuel injection system development, component wear and durability studies, engine friction analyses, lubricant testing and emissions evaluations.
Technical Paper

PFI, IVD, ORI, CCD, AND OVI IN THE BMW 318i

1992-10-01
922262
A vehicle test program was conducted to investigate the potential of combining several performance related evaluations into the California Air Resources Board (CARB) and Environmental Protection Agency (EPA) (proposed) 16,093-km intake valve deposit protocol. The 16,093-km (10,000-mile) tests, conducted with BMW 318i vehicles, were utilized to assess the gasoline- related effects on port fuel injector (PFI) flow, intake valve deposits (IVDs), octane requirement increase (ORI), combustion chamber deposits (CCDs), and oil viscosity increase (OVI). The test matrix was based upon four 1985 BMW 318i vehicles and four fuels. The four-fuel set consisted of three commercial gasolines and one pure chemical, iso- octane. Each of the four cars was tested on each fuel. During each 16,093-km test phase, the octane requirement and physical condition of the engine oil were evaluated.
Technical Paper

Instantaneous Unburned Oil Consumption Measurement in a Diesel Engine Using SO2 Tracer Technique

1992-10-01
922196
The contribution of lubricating oil to diesel engine particulate emissions is of concern not only because of stringent particulate emissions standards but also because of engine-to-engine variability. Unburned oil contributes directly to the particulate soluble organic fraction. A real-time oil consumption measurement technique previously developed was further refined to also measure real-time unburned oil consumption. The technique uses high sulfur oil, low sulfur fuel, and fast response, sensitive SO2 detection instrumentation. Total and unburned oil consumption maps over the engine operating range are presented. Results show that both total and unburned oil consumption generally increase as speed and load are increased. Unburned oil consumption shows some peaks at intermediate speed, high-load conditions. Oil consumption from individual cylinders was measured and shown to be approximately equal.
Technical Paper

On-Line Oil Consumption Measurement and Characterization of an Automotive Gasoline Engine by SO2 Method

1992-02-01
920652
An on-line oil consumption measurement system using the SO2 tracer method has characterized automotive gasoline engine oil consumption under various engine operating conditions, including a 200-hour durability test. An oil consumption map of total engine, individual cylinder, and valve train was produced for various speed and load ranges under both steady-state and step-transient operating conditions. The effect of spark timing as an additional engine parameter on the oil consumption was also investigated. Oil consumption maps have enlightened the conventional understanding of oil consumption characteristics and broadened the areas of concern for control technologies. This paper reports the benefit of the on-line oil consumption measurement system, the result of oil consumption history over the durability test, discrete measurement of oil consumption contribution within the engine, and various oil consumption characteristics affected by engine operating conditions.
Technical Paper

Investigation of a Spark-Assisted Diesel Engine

1983-02-01
830588
A single-cylinder, open-chamber direct-injection (OCDI) diesel engine was converted to low compression ratio, spark-assisted operation. A modular construction cylinder head was built for the test work. The research work indicated that on a typical OCDI diesel engine, several spark plug locations are possible to produce successful ignition of a wide range of fuels. Performance tests were run with different compression and swirl ratio combinations. The best combination was found to be 12.2 compression ratio and 10 swirl ratio. The spark-assisted engine (CR 16:1) was performance tested with methanol and DF-2 plus 20% methanol emulsified fuel. The spark was always required with methanol, however, with emulsified fuel spark was desirable for starting and warming up periods. The investigation suggested the feasibility of economically developing multi-fuel spark-assisted diesel engines.
Technical Paper

Synthetic Fuel Operation in a Heavy Duty Diesel Engine

1986-10-01
861538
A heavy duty (150 kW) diesel engine was tested to determine operational problems while running on minimally processed synthetic fuels. A reference No. 2 diesel fuel was compared with liquid products derived from shale, tar sands, and coal. Information on the engine setup and test procedure is presented. The test results include engine power, thermal efficiency, ignition delay, gaseous and particulate emissions, smoke opacity, cylinder pressure, and heat release data. Cold start data at 0°C and −20° C and idle deposit test results are also presented. These data should help to determine future engine modifications to enhance synfuel engine performance.
Technical Paper

Low Heat Rejection Engines

1986-03-01
860314
The paper gives a general overview of the state-of-the-art in low heat rejection (LHR) engines. It also gives experimental results obtained at SwRI with a single-cylinder research engine using an electrically heated cylinder liner to simulate LHR operation and examine the effects of increased liner temperature. It was concluded that the improvement in fuel economy from LHR operation is negligible in naturally-aspirated (NA) engines, about 7 percent in turbocharged (TC) engines and about 15 percent in turbocompound (TCO) engines. LHR operation reduces power in NA engines only. It increases NOx emissions by around 15 percent, but reduces HC and CO emissions. LHR operation offers benefits in the reduction of noise and smoke, and in operation on low cetane fuels. Much more research is needed to overcome the practical problems before LHR engines can be put into production.
Technical Paper

Observations from Cylinder Liner Wear Studies in Heavy Duty Diesel Engines and the Evolution towards Lower Viscosity Heavy Duty Engine Lubricants

2011-04-12
2011-01-1207
Since the invention of the internal combustion engine, the contact between piston ring and cylinder liner has been a major concern for engine builders. The quality and durability of this contact has been linked to the life of the engine, its maintenance, and its exhaust gas and blowby emissions, but also to its factional properties and therefore fuel economy. While the basic design has not changed, many factors that affect the performance of the ring/liner contact have evolved and are still evolving. This paper provides an overview of observations related to the lubrication of the ring/liner contact.
Technical Paper

Correlation of Air Fuel Ratio with Ionization Signal Metrics in a Multicylinder Spark Ignited Engine

2009-04-20
2009-01-0584
Accurate individual cylinder Air Fuel Ratio (AFR) feedback provide opportunities for improved engine performance and reduced emissions in spark ignition engines. One potential measurement for individual cylinder AFR is in-cylinder ionization measured by employing the spark plug as a sensor. A number of previous investigations have studied correlations of the ionization signal with AFR and shown promising results. However the studies have typically been limited to single cylinders under restricted operating conditions. This investigation analyzes and characterizes the ionization signals in correlation to individual AFR values obtained from wide-band electrochemical oxygen sensors located in the exhaust runners of each cylinder. Experimental studies for this research were conducted on a 2.0L inline 4 cylinder spark ignited engine with dual independent variable cam phasing and an intake charge motion control valve.
Technical Paper

Evaluation of Injector Location and Nozzle Design in a Direct-Injection Hydrogen Research Engine

2008-06-23
2008-01-1785
The favorable physical properties of hydrogen (H2) make it an excellent alternative fuel for internal combustion (IC) engines and hence it is widely regarded as the energy carrier of the future. Hydrogen direct injection provides multiple degrees of freedom for engine optimization and influencing the in-cylinder combustion processes. This paper compares the results in the mixture formation and combustion behavior of a hydrogen direct-injected single-cylinder research engine using two different injector locations as well as various injector nozzle designs. For this study the research engine was equipped with a specially designed cylinder head that allows accommodating a hydrogen injector in a side location between the intake valves as well as in the center location adjacent to the spark plug.
Technical Paper

Miller Cycle Application to the Scuderi Split Cycle Engine (by Downsizing the Compressor Cylinder)

2012-04-16
2012-01-0419
The Scuderi engine is a split cycle design that divides the four strokes of a conventional combustion cycle over two paired cylinders, one intake/compression cylinder and one power/exhaust cylinder, connected by a crossover port. This configuration provides potential benefits to the combustion process, as well as presenting some challenges. A Miller cycle configuration of the engine is made possible by turbocharging with a downsized compressor cylinder and has been modeled in 1-dimensional cycle simulation software.
Technical Paper

Scuderi Split Cycle Engine: Air Hybrid Vehicle Powertrain Simulation Study

2012-04-16
2012-01-1013
The Scuderi engine is a split cycle design that divides the four strokes of a conventional combustion cycle over two paired cylinders, one intake/compression cylinder and one power/exhaust cylinder, connected by a crossover port. This configuration provides potential benefits to the combustion process, as well as presenting some challenges; it also creates the possibility for pneumatic hybridization of the engine. This paper presents the methodology and results of a comprehensive study to investigate the benefits of air hybrid operation with the Scuderi Split Cycle (SSC) engine. Four air hybrid operating modes are made possible by the Split Cycle configuration, namely air compressor, air expander, air expander & firing and firing & charging. The predicted operating requirements for each individual operating mode are established. The air and fuel flow of the individual modes are fully mapped throughout the engine operating speed and load range and air tank pressure operating range.
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