Effect of injection condition and swirl on D.I. diesel combustion in a transparent engine system

The objective of this work was to investigate the effects of injection conditions and swirl on D.I. diesel combustion using a transparent engine system. The test engine is equipped with a common rail injection system to control injection conditions and to obtain split injection characteristics. A combustion analysis and steady flow test were conducted to measure the heat release rate due to cylinder pressure and the swirl ratio. In addition, spray and diffusion flame images were obtained using a high speed camera. The LII & LIS methods were also used to obtain 2-D soot and droplet distributions. High injection pressure was found to shorten ignition delay, as well as to enhance peak pressure. The results also revealed that the heat release rate in the premixed combustion region was markedly reduced through the use of pilot injection, while the soot distribution and the heat release rate in the diffusion combustion region were increased. The swirl effect was found to shorten ignition delay at certain injection timings, and to enhance the heat release rate in all experimental conditions.     

Investigation of soot formation in Diesel-GTL fuel blends under quiescent conditions

In this study, a visual investigation of sprays and flames is performed, and soot formation in Diesel-GTL fuel blends is studied in a specially designed quiescent constant-volume chamber under various ambient gas temperatures and O₂ concentrations. Similar to the case of soot formation during diesel fuel combustion, the sooting zone during the mixing-controlled combustion of Diesel-GTL blends is located in the leading portion of the jet boundaries. Auto-ignition delay and soot concentration decrease with an increase of GTL content in the fuel blend. Soot also decreases with lower O₂ concentration, higher injection pressure, and lower ambient gas temperature. The lack of soot formation at lower O₂ concentrations and lower temperatures suggests that Diesel-GTL fuel blends can be successfully utilized in low-temperature diesel combustion technologies that are currently being developed. Furthermore, this mixing controlled combustion method with Diesel-GTL blends can be used to modulate various engine operation parameters, and therefore to simultaneously reduce the formation of soot and NOx within a wide range of diesel engine loads.     

Performance analysis according to the combination of energy storage system for fuel cell hybrid vehicle

The need for the unmanned ground combat vehicle (UGCV), which is used for the surveillance, reconnaissance and targeting during extremely dangerous condition on the battlefield, has steadily increased, and the transition from manned ground combat vehicles to unmanned ground combat vehicles is expected to reduce the loss of lives during battle. The UGCV needs many types of capabilities to achieve satisfactory performance. This paper focuses on the modeling and control of the power system of the UGCV, and proposes the fuel cell hybrid system (FCHS) for the power system of the UGCV. The fuel cell hybrid system has many advantages in stealth drive and the system efficiency. In addition, the FCHS is much quieter than the engine generator and generates much less heat. The benefits of the FCHS are advantageous for use in Army operations, which require ‘silent watch’ capability and the ability to operate without showing up on an enemy’s radar screen. The FCHS has a fuel cell and uses an energy storage system (ESS) as a power source. The ESS (e.g., batteries or ultracapacitors) helps the fuel cell supply power to the electric drive system and also recovers energy during deceleration. The ESS makes it possible to improve the efficiency and dynamic characteristic of the power system. In this paper, the FCHS is composed of different combinations of component models. The component sizes are chosen to satisfy performance requirements. In order to determine the power distribution between the fuel cell and the ESS, a power management strategy based on the required power and the SOC (state of charge) of the ESS is proposed. Batteries and ultracapacitor, components of the ESS, have different characteristics. Accordingly, varying the combination of ESS components can change the performance of the power system. The performance of the FCHS with respect to different combinations of ESS is analyzed using simulated results.     

Development of evolutionary cone type LSD for SUV/RV utilizing the axiomatic approach and the ultrasonic nano crystal surface modification technology

Surface topology, cone angle and the forces acting on the cone of the clutch type limited slip differential (LSD) are major design parameters for the bias ratio and the noise condition. Therefore much research has been dedicated to these developments but the results have been used to submit patents. A new cone type limited slip differential for sport utility vehicles and recreational vehicles, which has a very simple structure and easy compliance with the vehicle performance, has been developed by the axiomatic approach and the ultrasonic nano crystal surface modification (UNSM) technology. The design criteria and optimal value of the design parameters are determined by the axiomatic approach utilizing CAE tools. Test methodologies in a test rig and in a vehicle were also developed. Test results showed good performance of bias ratio and noise level but durability is still under testing. This study is an extension of F2006P266, FISITA 2006.     

Design of Integrated Chassis Control logics for AFS and ESP

The performance of most electronic chassis control systems in the past has been optimized individually. Recently, a great research effort has been dedicated to the integration of chassis control systems in an effort to improve the vehicle performance. This involves orchestration of individual control modules so that they can jointly contribute to the enhancement of their control effect. In this research, two integrated control logics for AFS (Active Front Steering) and ESP (Electronic Stability Program) have been developed. Of the two logics, one uses a supervisor that rules over the individual modules. The other logic uses a CL (Characteristic Locus) method, which is a frequency-domain multivariable control technique. The two logics have been tested under various driving conditions to investigate their control effects. The results indicate that the proposed integrated control logics can yield vehicle performance that is superior to that of the individual control modules without any integration scheme.     

Tensile properties of different chemical compositions for TRIP-assisted multiphase steel for automobile structures

The microstructural changes and the tensile properties of TRIP-assisted steels resulting from different chemical compositions were investigated by using SEM, TEM, XRD and UTM. As a result of microscopic observation, the morphology of retained austenite could be characterized by two types: a granular type in steel containing higher Si and a film type in steel having higher C. In the case of the steel containing higher C with a tensile strength of 860 MPa and a total elongation of 38%, the film type retained austenite could be observed among the lath bainitic ferrites. Actually, the metastable retained austenite was required for good formability, which means that the chemical composition plays a significant role in the microstructure and tensile property of TRIP-assisted steel. With respect to the tensile property, each steel type that contained an suitable amount of Si and Mn demonstrated a typical TRIP effect on a stress-strain curve while steel that contained a higher Mn content exhibited similar behaviors, as demonstrated in the dual phase steels.     

Developing a conceptual model for sharing container terminal resources: a case study of the Gamman container terminal

It is an important matter closely connected with saving logistics costs, as well as encouraging national competitive power, to improve the productivity of container terminals by efficient utilization of container terminal resources. In this respect, this paper tries to suggest a conceptual model for sharing container terminal resources, taking as a case study the Gamman Container Terminal (GCT) in the port of Pusan. In so doing, it identifies what kinds of resources can be systematically shared from the viewpoint of their common use and draws some problems resulting from terminal operation by four operators at GCT. The model does not imply the conception that each terminal has its own resources individually, but recommends that tentatively-called Container Terminal Resource Management Center (CTRMC) should be established and operated in order to save operation and investment costs and improve operational efficiency. In addition, the continuous acquisition and life-cycle support (CALS) concept is imbedded in the model so that it can control the supply and demand of resources efficiently by sharing the database, through which the CTRMC can automatically identify the status of the excess or deficit of a certain resource in each berth at GCT.     

Numerical study of a light-duty diesel engine with a dual-loop EGR system under frequent engine operating conditions using the doe method

Exhaust gas recirculation (EGR) is an emission control technology that allows for a significant reduction in NOx emissions from light- and heavy-duty diesel engines. The primary effects of EGR are a lower flame temperature and a lower oxygen concentration of the working fluid in the combustion chamber. A high pressure loop (HPL) EGR is characterized by a fast response, especially at lower speeds, but is only applicable if the turbine upstream pressure is sufficiently higher than the boost pressure. On the contrary, for the low pressure loop (LPL) EGR, a positive differential pressure between the turbine outlet and the compressor inlet is generally available. However, a LPL EGR is characterized by a slow response, especially at low and moderate speeds. In this study, of the future types of EGR systems, the dual-loop EGR system (which has the combined features of the high-pressure loop EGR and the low-pressure loop EGR) was developed and was optimized under five selected operating conditions using a commercial engine simulation program (GT-POWER) and the DOE method. Finally, significant improvements in the engine exhaust emissions and performance were obtained by controlling several major variables.     

Low cost design of parallel parking assist system based on an ultrasonic sensor

This paper presents a low cost design and implementation of a parallel parking assist system (PPAS) based on ultrasonic sensors. Generally, a PPAS requires several types of sensors, such as an ultrasonic sensor, camera sensor, radar sensor and laser sensor for parking space detection. However, our proposed PPAS only requires two ultrasonic sensors on the front and lateral sides for parking space detection. Moreover, a steering angle sensor and wheel speed sensor installed in the vehicle are used to obtain vehicle position information for localization in ultrasonic range data. The hardware architecture of the PPAS based on an electronic control unit (ECU) module, sensor modules and a human machine interface (HMI) module was proposed. Moreover, the software architecture of the PPAS is based on system initialization, scheduling, recognition and a control algorithm. In particular, a novel sensor algorithm was proposed to minimize the vehicle corner error of the ultrasonic sensor. A prototype of the PPAS based on the proposed architecture was constructed. The experimental results demonstrate that the implemented prototype is robust and successfully performs parking space detection and automatic steering control. Finally, the low cost design and implementation of the PPAS was possible due to the cheap ultrasonic sensors, simple hardware design and low computational complexity of the proposed algorithm.     

Analysis of an automotive ground system based on its steady-state model

As more electrical equipment is installed and larger currents are required in vehicles, the automotive ground system becomes more important to guarantee the stable operation of the equipment and efficient power consumption. In this paper, an automotive ground system is analyzed in a steady-state condition, and a simulation model for estimating its ground voltage distribution is described. The automotive ground system is divided into an engine compartment ground and a body ground, and it is modeled as an equivalent resistor network, which is suitable for simulation. By using the developed model, ground voltages are simulated and measurements are taken with a real car. A comparison of the simulation and measurement results shows good agreement, and the validity of the model is confirmed. Then, the factors that dominate the ground voltage level are discussed.