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Technical Paper

A Grid Generating System for Automobile Aerodynamic Analysis

1991-02-01
910598
This paper describes a new grid generating system particularly designed for automobile external flow analyses. The system consists of three major parts as follows: Part I collects the geometrical data of the automobile surface and develops an intermediate grid. Part II generates the surface grid on the surface of the automobile. The surface grid is used as the boundary condition for generating the three-dimensional grid for the flow space. Part III generates the three-dimensional grid for external flow analyses. In generating the surface grid, a new approach of generating grid has been developed, in which two elliptic grid generation equations are solved directly on the physical domain. The three-dimensional grid is generated by the elliptic grid generation method blended with the hyperbolic method. An iterative solution algorithm based on the approximate factorization scheme has been developed.
Technical Paper

A Corrosion Resistant Alloy for Vacuum Brazed Aluminum Heat Exchangers

1991-02-01
910591
Vacuum brazed aluminum automobile radiators have exhibited a susceptibility to intergranular corrosion on the external tube surfaces, induced by road salt splash high in chlorides. A novel brazing sheet material with greatly improved perforation resistance has been developed to address this problem. Relative external corrosion resistance of conventional and experimental alloy systems was determined by accelerated corrosion testing of brazed composites and radiator sections in SWAAT. The new material, designated K319, exhibits an order of magnitude improvement in time to perforation in this test. A subsurface layer, anodic to the core alloy, is developed during the brazing process and accounts for the material's greatly enhanced resistance to perforation.
Technical Paper

Development of Pitting Corrosion Resistant Condenser with Zinc-Arc-Spray Extruded Multi-Cavity Tubing

1991-02-01
910592
We have developed a highly corrosion-resistant serpentine type condenser which is characterized by its manufacturing process that zinc is coated on the surface of a multi-cavity extruded tubing at the rate of 5-20 g/m2 by arc spray, and then, thus prepared tubing and corrugated fin stocks are brazed by the conventional Nocolok brazing process (Herein after this is referred to as ZAS NB process). By this brazing process as well as conventional flux brazing (FB) process, a highly pitting corrosion-resistant zinc diffusion layer is formed on the surface of the tubing at the time when brazing is operating. This newly developed method achieved improvements in productivity and quality of product.
Technical Paper

Accelerated Corrosion Test Methods for Evaluating External Corrosion Resistance of Vacuum Brazed Aluminum Heat Exchangers

1991-02-01
910590
A program to develop an aluminum tube stock alloy for vacuum-brazed heat exchangers with improved external corrosion resistance necessitated the use of accelerated laboratory corrosion tests to rank trial materials and ultimately qualify an alloy for production and sale. Brazed radiator sections and sheet samples were exposed to a variety of ASTM standard corrosion test environments. Metallographic examination of samples thus exposed demonstrated that the SWAAT test (ASTM G85:A3) closely replicated the air-side corrosion morphology found in aluminum radiators from the field. Samples exposed in test environments other than SWAAT did not generally exhibit the mixed intergranular/pitting morphology found in field retrievals. In neutral salt spray (ASTM B117), for instance, smooth-sided hemispherical pitting was the corrosion mode observed.
Technical Paper

Fusible Core Technology: From Research to Industrialization

1991-02-01
910587
Today, all automotive manufactures are interested in the fusible core technology. This technique makes it possible to advantageously manufacture inlet manifolds in plastic instead of aluminum. In plastic, weight is reduced by a factor of two and the performances of the engine are increased. Due to integration of functions during manufacturing the number of parts is reduced, thus resulting in cost reduction. A study of this process is presented. The results and understanding of this technology are currently incorporated in fully automated production lines.
Technical Paper

Composite (SMC) Engine Components

1991-02-01
910588
Engine design for the 1990's has to meet substantially tougher goals than in the past. With E.P.A. and C.A.F.E. edicts from Washington, a more sophisticated customer, and world competition, the big three automotive companies and truck manufacturers are looking at new designs and new materials to meet this challenge. Specifically, some of these goals are higher horsepower and torque per liter, reduced noise, lower weight, improved durability, better aesthetics, and lower cost to meet world competition. Material selection can play a large role in meeting the challenges for the 1990's. Composites are now being designed in many engine applications which have been traditionally metal. Proper design of these composites can provide many advantages over other materials. One promising thermoset composite is vinyl ester sheet molding compound, which is a vinyl ester resin matrix material using 30% glass fiber for reinforcement and is loaded into the mold in sheet form.
Technical Paper

Particle Sizing Using a Two-Dimensional Image

1991-02-01
910725
Particle size data is available from the scattered light pattern collected by a still camera in a typical particle image velocimetry(PIV) experiment. While most PIV experiments are primarily interested in fluid velocities for a seeded flow, in a fuel spray the spray droplets may be used as the scattering particles in dilute areas of the spray. Conventional PIV processing can provide a local average particle velocity in the plane of illumination. In addition, analysis of the scattering signature of the ensemble of particles in a small area of the PIV photograph can provide an average particle size. Examples of the proposed experimental technique will be given, as well as a suitable inversion scheme for obtaining particle size distributions from the diffraction pattern using an integral inversion.
Technical Paper

A Comparison of the Bosch and Zuech Rate of Injection Meters

1991-02-01
910724
This paper will discuss the fundamentals of the Bosch rate of injection meter which has been the standard measurement tool for the last 25 years and a newly developed tool which uses the Zuech constant volume technique. A fundamental and experimental comparison is presented. Using a high pressure accumulator type injector, each of the injection systems produced almost identical injection rate shapes. The integrated values of these traces (injection quantity) were within a few percent of the physically measured quantities.
Technical Paper

Exciplex-Based Fluorescence Method for Remote Probing of Fuel Droplet Temperature

1991-02-01
910729
Exciplex-based fluorescence was employed for the remote, nonintrusive, instantaneous and point measurements of fuel droplet temperature. A hydrocarbon droplet doped with naphthalene and TMPD was allowed to evaporate in a heated gaseous mixture of oxygen, nitrogen, carbon dioxide and water. The fluorescence emission spectra from a droplet subjected to nitrogen laser excitation were measured with an optical multichannel analyzer. Photographic observation showed that a droplet fluoresced with a green color at room temperature. As the temperature was raised, fluorescence became purple. The ratio of fluorescence emission intensities at two different wavelengths was an appropriate criterion for in situ determination of droplet temperature. Oxygen in the ambient gas was found to be a major quencher for the fluorescence. Droplet velocity relative to the ambient gas did not have an appreciable influence on the fluorescence emission spectra.
Technical Paper

Planar Liquid and Gas Fuel and Droplet Size Visualization in a DI Diesel Engine

1991-02-01
910726
In an optically accessible direct injection Diesel engine with pressure and temperature conditions close to those of actual engines, the gaseous and liquid phases of the fuel were simultaneously visualized by planar exciplex fluorescence to yield instantaneous information sensitive to droplet breakup and vaporization in a non-combusting spray. Semi-quantitative results were extracted from the technique to give spatially integrated ensemble average data concerning the temporal evolution of the mass concentration of the respective phases. The ensemble scattering polarization ratio technique was also applied to yield the droplet size and concentration at the leading edge of the jet. Within the jet core, planar measurements of the depolarization of elastically scattered light indicated the presence of longitudinal fluctuations in droplet concentration. Cycle to cycle coherence in the depolarization profiles was observed.
Technical Paper

Measurement of Soot and Flame Temperature Along Three Directions in the Cylinder of a Direct Injection Diesel

1991-02-01
910728
A single cylinder diesel engine with simulated turbocharging was instrumented and run to acquire radiation data at two wavelengths, simultaneously at three locations, along with cylinder pressure data and injection data. The 8 hole injector was indexed to acquire data, at three angles of 0°, 11° and 22.5° from the spray axis. The engine speed was 1500 rpm, the equivalence ratio (based on fuel to oxygen ratio) was 0.47, and the partial pressure of oxygen was 58 kPa for all runs. The radiation data were processed to produce the flame temperature and soot concentration using the two-color theory. The soot concentration and temperature increased in the outward radial direction, with the highest values at the 11° locations except for near the injector where the highest values were on the axis. The flame appeared to start at the spray tip when it was almost half-way distant from the bowl walls. The spray slowed down as it moved radially outward.
Technical Paper

A Quantitative Analysis of Schlieren Photography for an Internal Combustion Engine Diagnostics

1991-02-01
910730
This report describes the possibility of quantitative analysis of Schlieren photographs as an internal combustion engine diagnostic. Using a recently developed photographic analysis system, it was attempted to analyze Schlieren photographs. Results showed simple integration calculations produced significant distortion in the analyzed results. To eliminate the distortion, some correction techniques were developed in this research. Accuracy of the analyzed results were evaluated roughly with uncertainty analysis. The results showed that this analysis technique can be one of the approximate diagnostics for the measurement of fuel vapor and density distribution in internal combustion engine research. SCHLIEREN photography is one of the most popular visualization techniques in the research of internal combustion engines. Although the photographs have density information in themselves, they are used mainly for the purpose of qualitative visualization.
Technical Paper

Optical Diagnostic for Diesel-Sprays with μs- Time Resolution

1991-02-01
910727
Droplet formation and subsequent evaporation in Diesel sprays occur so fast that conventional diagnostic tools are generally too slow to resolve time dependent features. To overcome this drawback a very fast optical diagnostic system has been developed, providing a time resolution of 4 μs per sampling point over the full duration of automotive type Diesel sprays. In order to accomplish this high speed the simultaneously measurable quantities had to be reduced to the two most essential values: mean droplet size and number of droplets in the test section. A combined extinction-diffraction technique is used to determine the two free parameters in a generalized droplet distribution function which has been derived from a detailed analysis of spray characteristics using photo-graphic recordings of droplet distributions. It is shown that these two parameters are sufficient to characterize with good accuracy the full width of variations occuring in practical droplet distributions.
Technical Paper

The Low NOx Truck Engine

1991-02-01
910731
A brief study has been undertaken with exhaust gas recirculation (EGR) applied to a prototype low emission, heavy duty, direct injection (DI) diesel engine aimed at evaluating the potential for low nitrogen oxide (NOx) emissions. By virtue of the very low smoke levels achieved with the prototype engine, EGR can be applied at full load for substantial reductions in NOx down to c. 2.5 g/kWh (1.9 g/hph) over the European R-49 13-Mode test. These results were achieved with competitive particulates and fuel consumption and without recourse to engine de-rating. Compliance with the NOx emissions proposed for the year 2000 Japanese market was also demonstrated. These results are summarised in this paper and justify the need for a major research programme aimed at demonstrating the full potential of using EGR to develop a fuel efficient, low emission truck engine concept for the 1990's and beyond.
Technical Paper

JSAE Recommended Practice - Evaluating Method of the Automotive Distributed Control Multiplex Systems

1991-02-01
910716
While basic automobile performance is improving along with the growth of higher value-added features, rapidly increasing use of electrical and electronics systems with complex wire harnesses is becoming a problem. This is bringing the automotive distributed control multiplex system to commercial reality. At present, standardization of protocols is under deliberation by SAE and ISO, and several protocols are being considered as candidates. To select a multiplex LSI having an optional protocol, we have established a method to evaluate automotive distributed control multiplex system from the standpoint of users. The method will permit comparison of various multiplex LSIs including physical layers and their protocols' performance/reliability, while helping clarify their features and areas of applications. It is our hope that through this activity of ours, we will be able to make some contribution to global standardization in the field.
Technical Paper

Digital Signal Processor for Car Audio Application

1991-02-01
910795
A Digital Signal Processor(DSP) for audio application, especially for surround processing, has been developped. This LSI can control external delay RAM, which accumulates audio data to be delayed for surround processing. In order to reproduce surround sound faithfully, long delay time and high speed delay RAM access are necessary. Large external delay RAM space such as 2M bit and various address management operations are available. Minimum read access time 244ns and write access time 366ns are realized to simulate maximum to 85 reflected sounds.
Technical Paper

Unique Power Supply for Automotive Audio Power Amplifier

1991-02-01
910796
The pursuit of high performance sound systems demands increased power. Traditional approaches include bridge mode amplifiers and dc to dc step-up converters to achieve higher power outputs. Bridge mode amplifiers are now widely used. Cost, efficiency, and reliability are factors limiting the application of step-up converters. An integrated monolithic approach can overcome these limitations. Theoretically, this topology could yield an output in excess of one hundred and fifty Watts into a four ohm load.
Technical Paper

Three-Dimensional Simulation of the Flow in a Torque Converter

1991-02-01
910800
This paper describes a simulation study of the internal fluid flow of a torque converter. The study was conducted by using the steady-interaction technique to connect the boundaries between neighboring elements. This technique averages the flow variables in the circumferential direction on the connecting boundary surfaces. A comparison of computational results with experimental data gives an estimate of the accuracy in predicting torque converter performance with this method.
Technical Paper

Pop Noise in Automotive Audio Systems - Causes and Cures

1991-02-01
910797
The audible “pop” sounding noise heard at the loudspeaker when a radio and/or amplifier module is switched on/off has become generically known as “pop-noise”. This phenomenon has become a particularly sensitive issue in recent years especially to the “Big Three” in their drive to acquire true high fidelity sounding systems in the demanding automotive environment. The causes and cures are very well understood by power audio I.C. designers and producers and involve a close integration between optimization of IC design and final system implementation. This paper serves to explain these causes and what has been done to reach a satisfactory and acceptable cure.
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