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Technical Paper

Three-Dimensional Numerical Analysis of In-Cylinder Flows in Reciprocating Engines

1986-02-01
860464
This paper describes the results of the three-dimensional numerical analysis of swirl behavior in the cylinders and piston cavities of reciprocating engines under motoring conditions. The generation of swirl during intake stroke has been calculated in one model engine having an off-center intake valve and a flat piston. Furthermore, in the other model engine having a piston with a cavity whose configuration has been changed variously, the decay of swirl during compression stroke has been calculated. The results show that the process of induction swirl generation varies considerably with the inflow velocity distribution around the intake valve, and that in the cases of non-axisyrametric corolla-like cavities the swirl decays much more greatly than in the cases of axisymmetric cavities.
Technical Paper

International Congress and Exposition Detroit, Michigan February 24-28, 1986Measured Steady Flow Velocity Distributions Around a Valve/Seat Annulus

1986-02-01
860462
Measurements were made of the three velocity components at the exit plane of the intake valve from an internal combustion engine. The velocities were measured using hot-wire anemometry in a steady-flow rig, and an assessment was made of the effects of flow rate, valve lift, cylinder bore diameter, and inlet configuration on the velocity distribution around the intake valve. The results showed that over the range of flow rates tested, the normalized velocity profiles are independent of flow rate. At a fixed flow rate, the velocity profiles around the valve periphery are found to be strongly dependent on proximity to the cylinder head. Close to the cylinder head, the profiles are skewed but become more uniform as the distance from the cylinder head increases. In addition, the results indicate that the profiles are sensitive to the valve lift and to the proximity of the cylinder wall to the valve axis.
Technical Paper

Transient Cycle Emissions Reduction at Ricardo-1988 and Beyond

1986-02-01
860456
This paper describes techniques which have been developed to analyse the gaseous and particulate emissions from diesel engines over the US Federal heavy duty transient test cycle. This has included identifying the main sources of emissions during the test cycle, and analysis of the type of particulate. Some of the interesting observations from recent test work have been reviewed together with solutions that have reduced emissions levels. A computer simulation using steady state results has been presented which correlates well with measured values over the transient test cycle. Finally the paper considers the measures required to approach 1991 and 1994 emissions levels.
Technical Paper

A Review of Ideas for Improving Transient Response in Vehicle Diesel Engines

1986-02-01
860454
Turbochargers are rightly blamed for disimproving the transient response of vehicle Diesel engines, but the serious effect of engine rotating inertia is often forgotten. Ultimately, a “no coolant” engine with lightweight ceramic parts may give substantial improvements by increasing exhaust gas temperature and at the same time reducing the inertia of engine and turbocharger components. The response of a turbocharger system can also be improved by adding energy to it, but so far such additions have required complex and costly sub-systems. A novel, cheap system is suggested.
Technical Paper

Dynamic Behaviour of a Turbocharged Diesel Engine

1986-02-01
860453
The transient behaviour of torque and smoke produced by a turbocharged diesel engine has been measured by frequency response methods, with a sinusoidal perturbation applied to the fuel. A dynamic torque parameter (dmep) has been introduced and the response of this to changes in speed and load can be separated. The dmep also enables the delay associated with torque production to be obtained: this is compared to the widely accepted values. The results have also been analysed to show the relationship between air-fuel ratio and smoke produced during a transient. The conclusion is that the production of smoke under dynamic condition, behaves similarly to that under steady running but that it is more dependent on the initial load (air-fuel ratio) level.
Technical Paper

Supercharging with Comprex® to Improve the Transient Behavior of Passenger Car Diesel Engines

1986-02-01
860450
Transient conditions are typically encountered in passenger car engine operation, and they have a major impact on the control system driver/vehicle, as well as on emissions. While turbocharging generally deteriorates the transient behavior of a vehicle engine, supercharging with the pressure wave machine Comprex retains characteristics which are nearly equal to those of a naturally aspirated engine. The elements involved in the transient process are discussed, and their effect on road performance and emissions is shown on the basis of experimentally obtained data.
Technical Paper

Optimizing Press Performance for Difficult Automotive Stampings

1986-02-01
860440
A method has been employed in the stamping facility to reduce scrap by correlating observations from the press shop with laboratory test results. This paper illustrates the successful use of this method for reducing formability failures. Correlation of observed coating behavior with laboratory adherence tests is also discussed.
Technical Paper

The Effects of Zinc Coatings, Die Materials and Lubricants on Sheet Metal Formability

1986-02-01
860434
The results of a program Co evaluate lubricity test methods and different lubricant-tool-material combinations are described. This effort was specifically directed towards understanding soft and hard tool interactions and identifying the causes contributing to the discrepancies that exist between soft and hard tool trials on bare and zinc coated sheet steels. Both the LDH and drawbead simulation tests were evaluated, and it was concluded that either test can be used to adequately identify main effects and the Important lubricant-tool-sheet material interactions. However, the drawbead test was judged to be slightly superior because of its sensitivity to speed effects. More importantly, these results indicate that only for bare steels will the soft tool trials adequately predict hard tool performance.
Technical Paper

Effects of Coating Weight on the Resistance Spot Weldability of Galvanized Steel

1986-02-01
860436
The influence of coating weight on the weldability lobe and electrode life performance of a zinc-coated steel was studied. Variations in substrate chemistry, coating weight and welding process were minimized. Statistically quantified weldability lobes were generated for each material. The size and shape of these lobes were found to be relatively invariant to coating weight over the range of coating weights studied. However, the degree of scatter in the data increased with coating weight. Surprisingly, decrease in coating weight did not result in longer electrode life. The intermediate coating weight G60* showed the longest electrode life. Even though material and process variables were substantially minimized, a significant level of scatter in the weldability data was measured. The irregular electrode wear during weld testing is thought to be a major source of this variability.
Technical Paper

Bake Hardenable Continuous Annealed Drawing Steel Grades

1986-02-01
860439
Continuously annealing of cold rolled sheet offers the possibility of producing different steel grades with Bake Hardenability as a specific feature. Killed steel grades, from extra deep drawing (YS < 180 MPa) to drawing HSS (YS > 280 MPa) are obtained by adapting chemical analysis, rolling conditions and annealing treatment. Aging at room temperature does hardly occur and is without any consequence even for the most critical outer panels. The effects of deformation, baking time and temperature are determined by tensile and indentation tests. The conclusions from both tests, are similar. In the as shipped condition (Temper rolled), substantial bake hardening (BH), even without prestrain, is obtained under industrial baking conditions. With increasing prestrain the baking temperature and the time to reach the maximum BH decrease. The highest BH is found in the lower prestrain levels.
Technical Paper

Scatter of Structureborne Noise in Four Cylinder Motor Vehicles

1986-02-01
860431
Scatter of the structureborne component of interior noise can be as high as. 15dS for nominally identical vehicles. A hybrid analytical and experimental model of structureborne noise generation has been employed to evaluate the scatter problem, and it is shown that the essential features of structureborne noise scatter are reproduced using this technique. Structural - acoustic transfer functions may be used to characterise the nature and extent of structureborne noise scatter.
Technical Paper

A Comparison of the Resistance Spot Weldability of Hot-Dip and Electrogalvanized Sheet Steels

1986-02-01
860435
The majority of exposed and semi-exposed light gauge automotive components are being rapidly converted to metallic zinc coated steels. Since resistance spot welding is the dominant method of joining these parts, the weldability of a. variety of coated products was evaluated to facilitate direct comparison between hot-dip and electrogalvanized steels. The results indicate that the electrode life of electrogalvanized zinc and zinc-iron and hot-dip galvanized A40 materials are far superior to that of hot-dip galvanized zinc products. Some difference in current level for producing acceptable welds was observed between hot-dip and electro products. However, the substitution of electrogalvanized for hot-dip galvanized products of the same coating type will probably require only minor, if any, changes in current level in production situations. Further work is required to fully explain the differences in weldability noted between hot-dip and electrogalvanized materials.
Technical Paper

Noise and Vibration in Power Transmission Belts

1986-02-01
860428
Various types of belts are used for transmitting power between input and output shafts. Energy is transferred through contact of a flexible element: the belt, with relatively rigid pulleys. Due to imperfections in the system, noise and vibration are generated. After a literature review outlining possible noise generating mechanisms by analogy to similar problems, the nature of belt imperfections and related measurement methods are discussed. Simple models are presented to explain the different phenomena occurring during the operation of a drive, relationships between noise and vibration are brought out, and recommendations for belt design, manufacturing and testing are formulated.
Technical Paper

A Cost Benefit Analysis of Diesel Power

1986-02-01
860419
Since Diesel and Otto cycle powerplants of equal performance are rarely found in the same vehicle comparisons are difficult and confusing. However, enough data is available to develope a somewhat objective approach when purchasing family transportation. Also, while certain subjective criteria will always ensure a market for a number of diesel powered automobiles, an analysis of the lifecycle costs of owning and operating these cars indicates that they may not be for everyone.
Technical Paper

The Friction of a 1.6 Litre Automotive Engine-Gasoline and Diesel

1986-02-01
860418
The important influence of engine friction on fuel economy has aroused new interest in its accurate measurement. Ricardo have developed a new system of instrumentation capable of measuring mechanical friction under any steady engine running conditions, and isolating the proportion of engine power absorbed by each of the auxiliary drives. Furthermore, auxiliary drive torque is measured instantaneously as a function of crank angle, enabling the dynamics of the drives to be studied. The instrumentation can be easily adapted to fit most engine types and configurations whilst retaining the original auxiliary drive design. Results obtained from gasoline and diesel versions of a 1.6 litre automotive engine using this instrumentation are described. Mechanical friction, pumping losses and auxiliary drive losses were measured with engine load, speed and coolant temperature varied.
Technical Paper

Influence on Injection and Combustion Phenomena by Elimination of Hole Nozzle Sac Volume

1986-02-01
860416
For the reduction of unburned hydrocarbon emission from DI diesel engines nozzle sac volume is reduced and, in some cases, eliminated by covering the orifice with a valve. Studies on the sacless nozzle, however, clarified that it seriously influences the injection phenomena : i. The state of the fuel spray is different at each spray hole and at each needle lift. ii. Facilitates the combustion gas blow-back into the nozzle. The following are elucidated through this study : i. Irregular state of spray bases on flow line at the space between seat and needle different for each orifice and for each needle lift. ii. Gas blow-back occurs when needle bouncing and cylinder gas oscillation take place at the same time.
Technical Paper

Emission Controls for a 2.2L Diesel Engine

1986-02-01
860417
Abstract The adoption of stringent emission control requirements for diesel powered vehicles has generated the need for emission reducing engine controls. An exhaust gas recirculation system controlled by a true mass airflow sensor has been developed for a light duty truck equipped with a 2.2 liter, naturally aspirated, diesel engine to satisfy these requirements. An intake air throttle provides a method of reducing the intake mass airflow to the engine. The air/fuel ratio, which will simultaneously obtain the desired NOx emission level and minimize any increase in particulates, is achieved by a combination of intake air throttling and introduction of exhaust gas recirculation. The control system reduces emission output in a simple, cost effective manner, without adversely affecting fuel economy or driveability.
Technical Paper

Prediction of Transient Diesel Sprays in Swirling Flows via a Modified 2-D Jet Model

1986-02-01
860332
A model for predicting the spray behavior in an air swirl was developed. High speed Schlieren photographs of a non-evaporating spray in an air swirl were taken with a constant volume vessel which can generate various swirl intensities. A close observation of the photographs revealed that the spread of the spray in the direction perpendicular to the swirl flow is hardly affected by the swirl flow and that the spray is roughly divided into two regions; the main jet region which possesses a major part of momentum and the peripheral region which is torn off the main jet region by the swirl and flows with the same velocity as the local swirl velocity. Basing on this observation a 2-D model proposed by Sinnamon et al. was modified, so that the model was able to predict the spread, trajectory and penetration of a spray in a satisfactory manner.
Technical Paper

Control-Analysis-Planning-Execution of Operations in Computer Aided Manufacturing

1986-02-01
860263
This paper presents a methodology for applying computer based logic to control information in manufacturing. This methodology is evolutionary and reorganizes traditional planning and control activities on the basis of functional needs. The methodology is developed in the context of a high volume, repetitive, manufacturer of pressed metal products. Implementation of the methodology is conducted in a modular fashion. There are three major inter-related, integrated functional modules designed to operate within the current manufacturing environment but expandable to Just-in-Time manufacturing operations.
Technical Paper

Model for Predicting Air-Fuel Mixing and Combustion for Direct Injection Diesel Engine

1986-02-01
860331
Based on a multi-zone spray-mixing approach, an air-fuel mixing and combustion model for a Direct Injection Diesel engine is presented. The predictions from the model show very good agreement with the experimental data for various engines under a wide range of operating conditions. Major physical processes are modeled and validated independently. The atomisation process is based on Binary Drop Division concept. Fuel droplets are considered randomly distributed in the spray. A spherico-symmetrical transient drop evaporation model is used for evaporation calculation. A 3-dimensional spray-swirl interaction is modeled on centreline velocity vector/continuum approach. Turbulent mixing is characterised considering all possible available energy sources in DI diesel engines.
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