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Technical Paper

Calibration of Laser Fluorescence Measurements of Lubricant Film Thickness in Engines

1988-10-01
881587
A laser fluorescent diagnostic method was employed to measure lubricant film thickness on the cylinder wall/piston interface of two engines. The system output signal was calibrated using lubricant samples of known thickness, and by comparison of a known piston ring profile to measured lubricant film contours. Agreement of the results of the two calibration methods was within 5%. A relative calibration was performed with three oils having different additive packages, and with an oil contaminated through use in a commercially operated engine. The calibration coefficients for the oils, relating output voltage to film thickness, varied within a factor up to two, depending on lubricant type and age. The laser fluorescent apparatus was installed for use with a single cylinder test version of the Cummins VT-903 diesel engine. An optical passage was created through the block and cylinder wall using a quartz window.
Technical Paper

A Study on Needle Crystals Formation in Engine Oils Containing a Magnesium-Based Detergent

1988-10-01
881588
In the case of some engine oils, under specific conditions, engine oil additives may precipitate in the form of needle crystals which cause clogging of oil filters. A simple laboratory test has been developed to study the formation of needle crystal precipitates in engine oils. The influences of various conditions and the combination of engine oil additives on this formation were investigated using this test procedure. This laboratory testing showed that needle crystals form when the engine oil containing a magnesium-based detergent comes into contact with both water and carbonic acid gas under restricted conditions. It was discovered that there is a large difference in the formation of needle crystals between different magnesium-based detergents. The addition of suitable additives could prevent the formation of needle crystals even in those oils which cotain magnesium type detergents which are prone to form needle crystals.
Technical Paper

Catalyst Performance Study Using Taguchi Methods

1988-10-01
881589
A study was conducted to determine the effects of various factors on the performance characteristics of aged monolithic catalytic converters. The factors that were evaluated were catalyst volume, converter configuration (number of elements), catalyst supplier, “washcoat technology”, rhodium loading, platinum loading, and palladium loading. This study was also designed to evaluate the interactions among the various factors. To improve the efficiency of the study a 2-level fractional factorial experiment was designed using the Taguchi method. That made it possible to study the effects of the seven main factors and six interactions by evaluating only 16 different samples. The study helped sort the factors that had significant effects and helped quantify their effect on catalyst performance. This paper details the methodology used to design the experiment and analyze the results.
Technical Paper

A Reliable Single Cylinder Engine Test for Evaluation of Today's Heavy-Duty Diesel Oils for Oil Consumption and Piston Deposits

1988-10-01
881582
This paper reports a lubricant study conducted on a Caterpillar 1Y540 single-cylinder engine test equipped with a 34068 truck production piston. The sequence test, run under well controlled conditions for a large number of CE and CD+ diesel oils, shows a good discrimination of the lubricant for oil consumption and piston deposits and similar to that given by new North American multicylinder engine tests utilizing LTL pistons. Owing to its excellent reliability, adequate severity, and availability of hardware parts, this engine test provides a suitable alternative for replacement of the Caterpillar 1G2 and EMA SCOTE-1.
Technical Paper

Factors influencing Lubricant Performance in the Sequence VE Test

1988-10-01
881581
In the Sequence VE test, combustion-derived contaminants provide the dominant stress on the lubricant's ability to maintain engine cleanliness and prevent wear. Contamination levels in the Sequence VE test are as much as twice as high as in the Sequence V-D. This is accomplished by hardware and operational design, and is demonstrated by analysis of used-oil contaminant levels. The control of sludge deposits by dispersants is essentially a stoichiometric process. The VE test responds very well to increased dispersant treatment in proportion to the increased contaminant load. Chemical analyses of the blowby gases and used VE engine oils offer insight into mechanisms by which engine sludge and wear are generated. Acidic species in the oil appear to play a major role. VE wear also contributes to establishing sludge severity, but this can be avoided by controlling wear with the proper balance of conventional inhibitors.
Technical Paper

Use of Naphthenic Base Stocks in Engine Oil Formulations

1988-10-01
881585
The use of naphthenic base stocks in the formulation of engine oils has always been restricted due to certain physico-chemical properties (i.e. low oxidation stability, high volatility, great variation of the viscosity with the temperature) as well as the limited availability of this type of base oil in many parts of the world. However, modern additive technologies have permitted the formulation of high quality engine lubricants that incorporate a considerable proportion of naphthenic base stocks. This paper summarizes the experimental results followed in the development of a crank-case engine oil formulation SAE 40. API SF/CC with maximun usage of a naphthenic base stock MVIN-170 combined with HVI stocks and conventional additive technologies.
Technical Paper

Advances in the Use of Tritium as a Radiotracer for Oil Consumption Measurement

1988-10-01
881583
The oil consumption of a turbocharged, aftercooled direct-injection truck diesel engine was measured using a tritium-tracer technique. The advantages of the method over other chemical and radioactive tracers are described, and supplemented with data from radioanalysis of tritiated oils. As a proportion of fuel consumption, the oil consumption was shown to range from <0.1% to >0.4% depending upon the engine's load and speed, with the highest consumption at idle and at full load conditions. The mass consumption rate ranged from 6 g/h at light load, low speed to 230 g/h at full load, rated speed. The contribution of consumed oil to another truck engine's particulate-bound hydrocarbon emission was shown to be greatest at light and intermediate loads and negligible at high loads. The implications of these observations on diesel particulate control are discussed.
Technical Paper

Conceptual Design of a STOVL Fighter/Attack Aircraft

1988-10-01
881431
Short takeoff vertical landing (STOVL) aircraft offer unique basing and operational advantages to improve the capabilities of military forces in future warfare. To develop a STOVL fighter design with supersonic capability requires the integration of an advanced propulsion system into the airframe design. A promising propulsion system for supersonic STOVL application is the relatively new Hybrid Fan Vectored Thrust (HFVT) concept. This advanced Tandem Fan concept incorporates a dual-cycle engine with front and rear fully vectorabie nozzles of the three-poster type, to provide the required performance. In this paper, the HFVT STOVL design integration approaches for a conceptual fighter/attack aircraft, as well as some features of the resulting design, will be presented.
Technical Paper

Development of Transparent Cylinder Engines for Schlieren Observation

1988-10-01
881632
A square piston engine and a side-view collimating (SVC) cylinder engine are developed for side-view schlieren visualization of in-cylinder processes. The square piston engine has a square cylinder with two flat quartz windows permitting optical access to the entire cylinder volume. Compression sealing is provided by three polyimide ring assemblies which maintain the windows clean during the actual observation. In contrast with the square piston engine, the SVC cylinder engine permits to take schlieren photographs in practical engine geometries. This is made possible by designing the SVC cylinder so that it does not disperse parallel light rays. The physical principle and optical property of this cylinder are described. High speed schlieren movies were taken with these two transparent cylinder engines. Typical pictures, such as those of flame propagation, unburned gas motion, and formation of fuel and air mixture, are presented.
Technical Paper

Considerations of Control Authority Requirements in STOVL Propulsion System Sizing

1988-10-01
881432
Adequate control authority for a STOVL aircraft during very low speed and hover flights is critically important and must be considered during the aircraft preliminary design and refinement stages. Total control authority must be sufficient to trim the aircraft; to maneuver the aircraft in all axes in a satisfactory manner; to suppress external disturbances such as winds and gusts; to counter environmental changes such as atmospheric conditions, hot gas re-ingestions and suckdown effects; to counter asymmetric weapons loading; and to provide stability if automatic stability augmentation system is required. These considerations will impose additional requirements on the propulsion system and, if not dealt with early in the design process, may compromise the total performance of the aircraft. In this paper, the control authority requirements of a STOVL aircraft as imposed by the flying qualities requirements and other environmental considerations will be discussed.
Technical Paper

LDA Measurement of Turbulent Flow in a Motored and Firing Spark-Ignition Engine with a Horizontal Prechamber

1988-10-01
881636
To make clear the influence of a torch jet flow on the combustion process, a laser Doppler anemometer (LDA) is used to measure the mean velocity and turbulence intensity in a spark ignition engine with an unscavenged prechamber connected to a main chamber by a torch nozzle of different area sizes. The test engine is operated at a constant speed of 16.7 rps (1000 rpm), a constant volumetric efficiency of 80±2% and MBT for each torch nozzle area under firing as well as motored conditions. The LDA system is a dual beam forward scatter type, and its signals are acquired quickly and stored in a memory through a frequency tracking system. The LDA measurements are made at several locations in the main chamber. In the present paper, the turbulence is defined as the high frequency component of velocity above a cut-off frequency (0.75 kHz), and a cycle resolved analysis is performed to obtain the mean velocity and turbulence from individual cycle.
Technical Paper

Considerations in the Design of an Inexpensive Hydrogen-Fueled Engine

1988-10-01
881630
Present research efforts are pursuing the development of complex fuel delivery systems in an effort to successfully incorporate existing combustion chambers and coolant systems designed for hydrocarbon fuels into a hydrogen-fueled engine design. This paper presents the hypothesis that fundamental redesign of the combustion chamber shape and coolant passages can solve the hydrogen engine design problems more economically than redesign of the fuel delivery system. The differences in knock with hydrogen fuel and with hydrocarbon fuel are discussed. It is concluded that the combustion chamber shapes designed to reduce knock with hydrocarbon fuel actually promote knock with hydrogen fuel.
Technical Paper

Simulation Evaluation of Transition and Hover Flying Qualities of the E-7A STOVL Aircraft

1988-10-01
881430
A generalized simulation model has been prepared for use in conducting piloted evaluations of short takeoff/vertical landing aircraft, and an initial fixed-base simulation of the General Dynamics E-7A configuration has been completed. Objectives of the simulation were to define the acceptable transition flight envelope, determine control power used during transition and hover, and evaluate the integration of the aircraft's flight and propulsion controls to achieve good flying qualities throughout die low-speed flight envelope. Results provide a general view of the acceptable transition corridor, expressed in terms of minimum climb capability. Pilots' evaluations indicated that Level 1 flying qualities could be achieved for deceleration to hover in instrument conditions, for airfield landings, and for recovery to a small ship when attitude and velocity stabilization and command augmentation control modes were provided.
Technical Paper

Imaging of Engine Flow and Combustion Processes

1988-10-01
881631
As a means of exploring the use of optical imaging techniques in the study of engine flow and combustion problems, we have applied several imaging techniques in different laboratory engines and engine flow simulators. Two single cylinder research engines were employed: a sidewall-valved engine and a square piston engine. Additional observations were made of the free jet flowing from a liquid fuel injector, the intake valve air flow in a steady flow facility, and the mixed fuel/air intake flow following the impingement of a fuel spray on the backside of a valve. We used the planar imaging of laser induced fluorescence from OH to mark the position of the propagating flame front in the engine. These results are compared to similar data obtained using a Mie scattering technique employed in an earlier study.
Technical Paper

The Effect of Reduced Combustion Chamber Heat Loss on Combustion and Emissions of Alternative Fuels in a Light-duty DI Diesel

1988-10-01
881628
A research program was conducted to determine the effects of thermal barriers in the combustion chamber on emissions and combustion of a direct-injection diesel engine operated on selected alternate fuels. Steady-state exhaust emissions, cranking characteristics and combustion data of a baseline water-cooled engine were compared with those of a heat insulated uncooled engine with both engines operated on a reference fuel and two alternate fuels. A high compression ratio water-cooled engine with intake air heating was also included in the study. Operating the baseline water-cooled engine on alternate fuel generally raised the level of exhaust emissions. In addition, ignition delay and the rates and relative amounts of premixed and diffusion burning were significantly altered when the baseline water-cooled engine was tested with alternate fuels.
Technical Paper

A High Pressure Sealing System for Linear Actuators

1988-10-01
881436
A unique sealing system for actuators operating at 8000 psi has been designed and tested. Two actuators incorporating this sealing system have been tested, one with MIL-H-83282 hydraulic fluid and the other with chlorotrifluoroethylene (CTFE) fluid. The rod sealing system is a two-stage seal; the first stage is a laminar pressure drop and the second stage is a conventional low-pressure rod seal. The piston sealing system consists of standard seals supported by pressure-energized metal backup rings. This paper describes the sealing system, test actuators, pumping systems and test results.
Technical Paper

The Department of Energy's Federal Methanol Fleet - A Progress Report

1988-10-01
881629
The Federal Methanol Fleet Project, a demonstration authorized by the U.S. Congress in fiscal year 1985 and managed by the Oak Ridge National Laboratory (ORNL) for the Department of Energy, has operated methanol-fueled vehicles for nearly three years with a total of 20 methanol vehicles and 19 comparable gasoline vehicles now operating at three different sites. This paper summarizes the results and comparisons of the various fleet operations thus far. Over 700,000 miles (1 million kilometers) of operation have been accumulated. Methanol vehicle performance has been quite satisfactory with drivers rating them nearly as highly as the gasoline vehicles. The methanol fleet at Argonne National Laboratory has been specially equipped for cold-weather operation, and performance of the methanol vehicles in those circumstances has been very adequate. Data are presented showing that the drivers' ratings of the methanol vehicles at Argonne have only moderate dependence on ambient temperature.
Technical Paper

Engine and Constant Volume Bomb Studies of Diesel ignition and Combustion

1988-10-01
881626
Changing fuel quality, increasingly stringent exhaust emission standards, demands for higher efficiency, and the trend towards higher specific output, all contribute to the need for a better understanding of the ignition process in diesel engines. In addition to the impact on the combustion process and the resulting performance and emissions, the ignition process controls the startability of the engine, which, in turn, governs the required compressions ratio and several of the other engine design parameters. The importance of the ignition process is reflected in the fact that the only combustion property that is specified for diesel fuel is the ignition delay time as indicated by the cetane number. The objective of the work described in this paper was to determine the relationship between the ignition process as it occurs in an actual engine, to ignition in a constant volume combustion bomb.
Technical Paper

The Current Status of the Flight Test of the ASKA

1988-10-01
881433
The four engined Upper Surface Blowing (USB) STOL research aircraft ASKA was developed by National Aerospace Laboratory of Japan and has been in the flight test phase to provide various kinds of flight data. The position error in airspeed and angle of attack is discussed, and the low speed performance demonstrated in the flight test is provided by the figures of lift/drag coefficient curves and V-Gamma plot. Several indications of powered lift and dynamic stability derivatives obtained from the V-Gamma plot are discussed. The flight measured pitching moment shows the distinctive features such as pitch up tendency. The wing-body pitching moment and the downwash angle are analyzed from the flight load measurments of the horizontal tail. The ground effect of the ASKA is also presented quantitatively in this paper.
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