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Analysis on the Thermal Stress of Exhaust Manifold in a Heavy-Duty Diesel Engine by Conjugate Heat Transfer Method

Institute for Advanced Engineering-Sang-Kyoo Lee, Dong-Ryul Rhim, Min-Jung Kim
Agency for Defense Development-Jeong-Il Seo
  • Technical Paper
  • 2007-08-0078
Published 2007-05-23 by Society of Automotive Engineers of Japan in Japan
The exhaust manifold in a heavy-duty diesel engine should be strictly designed on the thermal performance. The current study is to get the temperature distribution and heat transfer coefficients at the walls of the exhaust manifold using a conjugate heat transfer method with the consideration of exhaust gas flow and convective heat transfer. Thermal deformation of the exhaust manifold owing to the thermal stresses is investigated by coupling the temperature distribution into a structural analysis code.
 

Prediction of DPF Performance Under NEDC Mode

Institute for Advanced Engineering-Sang-Up Lee, Dong-Ryul Rhim, Min-Jung Kim
General Motors Corporation Daewoo Auto and Technology Co.-Soong-Kee Kim, Ki-Kyung Bae
  • Technical Paper
  • 2007-08-0113
Published 2007-05-23 by Society of Automotive Engineers of Japan in Japan
In this analytical research a commercial CFD code was used to study DPF performance with the consideration of several factors. Temperature distribution, pressure drop and, PM filtering/regeneration were predicted with the input data from engine bench tests at an NEDC mode.
 

Evaluation of Discomfort Due to Vertical Feet Vibration at a Driver's Sitting Posture

Institute for Advanced Engineering-Han-Kee Jang, Seok-Hyun Choi
Ecole Nationale Supérieure des Mines-Karine Ruquet
Published 2007-05-15 by SAE International in United States
Floor vibration in a passenger car is getting more interest with the improvement of its NVH quality. International standard ISO 2631 provides frequency weightings for the evaluation of vibration on floor as well on seat at a sitting posture and has been widely used in automotive industry. However, since these frequency weightings were originally derived from an erect sitting posture and vibration magnitude of more than 0.5 m/s2, it can not describe well human response to the feet vibration in a passenger car any longer because of the two reasons; First reason is that the erect posture gives quite different dynamic characteristics of a human body compared to the inclined sitting posture in a passenger car. Second reason is magnitude level of 0.5 to 5 m/s2 where the frequency weightings of ISO 2631 were determined can not stand for the real situation of floor vibration of a passenger car of nowadays. Recent studies showed frequency weighting curves depend on the vibration magnitude, and therefore it is necessary to determine a new frequency weighting for the…
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Geometric Effects of Wall Flow Monoliths on Pressure Drop

Institute for Advanced Engineering-Dong-Ryul Rhim
Chonnam National Univ.-Byung-Chul Choi
  • Technical Paper
  • 2005-03-0045
Published 2005-08-22 by Society of Automotive Engineers of Korea in South Korea
Since wall flow monoliths which have become the most common substrate for diesel particulate filters have high flow resistance genetically because of their alternatively plugged channels, it is very important to reduce pressure drop during designing a diesel particulate filter with the wall flow monolith. The geometric factors such as diameter, length and volume are basic parameters to be considered to reduce pressure drop. In this study, the effect of the geometric factors has been studied in terms of pressure drop with an air flow test rig and an analytical method. Various silicon carbide filters with different volume, frontal area and length have been tested on the flow rig. The main factors for pressure drop were turned out to be the frontal area and length of filters while there is no definite correlation between volume and pressure drop. The cold air flow rig test data could be used for predicting actual back pressure during engine running with a reasonable accuracy by using Reynolds analogy.
 

Measurement of 6 Degree of Freedom Movement of Human Head in Low Frequency Range

Institute for Advanced Engineering-Han-Kee Jang
Center for Noise and Vibration Control(NOVIC), Dept. of ME, KAIST-Jeung-Hoon Lee, Hong-Seok Ko, Kwang-Joon Kim
Published 2003-05-05 by SAE International in United States
Motion-sickness is one of the major topics in research of human responses to vibration especially in the very low frequency range. For a study of this motion-sickness, measurements of 6-degree of freedom (DOF) movement of the human head for a long duration must be made. A safety helmet and accelerometers can be employed to measure the 6-DOF human head motion. This paper presents several problems and results in this approach.
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Model-Based Architecting for Reliability, Availability, and Maintainability Software in Automotive Applications

Institute for Advanced Engineering-Joong Yong Park
Ajou Univ.-Jong Min Choi, Il Sang Yoo, Young Won Park
Published 2002-03-04 by SAE International in United States
The importance of defining requirements correctly in the development process of software is well known in software industry. Since RAM(Reliability, Availability, and Maintainability) is a significant effectiveness element for the operation of automotive engine, it requires a thorough analysis during the design and testing of an engine. In this study, user requirements for the calculation of RAM and RG(Reliability Growth) were identified and documented by using a Model-Based Systems Engineering (MBSE) tool, RDD-100. The tool supports the traceability of each function to the corresponding requirement. Requirements were organized into behavior items such as RAM calculations, display, and data query and into non-behavior items such as input, output, and environment conditions. Additional requirements were derived if new functions are needed in the software even if the originating requirements did not exist in the early stage of the software development. Scenarios that describe the analysis of RAM and RG of the automotive engine were constructed to explain the activity and data flow among users, RAM software, and engine database. The top-level architecture of this software was designed…
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Measurements and Modeling of Residual Gas Fraction in SI Engines

Institute for Advanced Engineering-Hanseong Cho, Kwiyoung Lee
Ajou University-Jonghwa Lee, Jaisuk Yoo
Published 2001-05-07 by SAE International in United States
The residual gas in SI engines is one of important factors on emission and performance such as combustion stability. With high residual gas fractions, flame speed and maximum combustion temperature are decreased and there are deeply related with combustion stability, especially at Idle and NOx emission at relatively high engine load. Therefore, there is a need to characterize the residual gas fraction as a function of the engine operating parameters.A model for predicting the residual gas fraction has been formulated in this paper. The model accounts for the contribution due to the back flow of exhaust gas to the cylinder during valve overlap and it includes in-cylinder pressure prediction model during valve overlap. The model is derived from the one dimension flow process during overlap period and a simple ideal cycle model.The results showed that the residual gas fraction prediction model coincides well to the measured data over a wide range of engine operating condition such as intake pressure, air-fuel ratio, cam phasing and so on. This model can be used for calculating the residual…
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Dynamic Characterization of Foam Materials and Its Application to Modeling of Automotive Seat-Passenger System

Institute for Advanced Engineering-Han-Kee Jang, Seung-Han Kim, Young-Ho Cho
KAIST-Chang-Kook Chae, Suyon Song, Kwang-Joon Kim
Published 2001-04-30 by SAE International in United States
Dynamic properties of flexible polyurethane foam materials for car seats are highly complicated. In this paper, characterizations of dynamic stiffness of several foam specimens based on static stiffness obtained from IFD(Indentation Force Deflection) curve measurements are presented. It is observed that dynamic stiffness and its drift with static loading duration in logarithmic scale are proportional to the static stiffness at a given static loading regardless of types and dimensions of the foam. A three degree-of-freedom model of seated human body based on apparent mass measurements together with the characteristics of foam materials were incorporated for transmissibility prediction of the passenger-seat system.
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Some Aerodynamic Aspects of Centrifugal Fan Characteristics of an Automotive HVAC Blower

Institute for Advanced Engineering-Eui-Yong Kwon, Kyung-Wook Baek, Nam-Hyo Cho
Korea Delphi Automotive Systems Corp.-Han-Kyung Kim, Ik-Jin Jung
Published 2001-03-05 by SAE International in United States
Experimental and numerical approaches were adopted to understand flow behavior and performance of centrifugal fans in an automotive HVAC blower system. This work is directed at improving the performance of a conventional forward-curved centrifugal fan for a given small scroll casing. Recent requirements in the design of the multiblade centrifugal fan being used in automotive HVAC blowers are not only higher pressure rise and lower noise, but also better packaging in the automobile cabin. In order to meet these requirements, among various well-known design factors affecting the fan performance, principal parameters related to the rotor shape were modified and detailed flow analysis was carried out. Measurements have been made by means of a miniature five-hole probe and a pressure scanning system connected to an online data acquisition system. Computational results gave reasonably good predictions at the best efficiency operating point and verified the reliability of the present numerical approach. Based on the inspection of both measured and predicted results of the conventional fan, design improvements were carried out in an acceptable operation range, giving considerable…
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Simulator for forward collision warning and avoidance system

Institute for Advanced Engineering-Byoung-keun Oh, Woo-kug Hwang, Byung-suk Song
  • Technical Paper
  • 2000-05-0364
Published 2000-06-12 by Society of Automotive Engineers of Korea in South Korea
This paper presents a simulator for Forward Collision Warning and Avoidance (FCWA) system. The proposed simulator is composed of a personal computer as a controller, a 24 GHz radar, a warning and brake lamp, a buzzer and a lead vehicle model which is driven by two AC servo motors. A FCWA algorithm determines the warning and braking headway distance by road surface condition (wet/dry), following vehicle velocity, and relative velocity. The simulator has been designed and used to test a FCWA algorithm under realistic operating conditions in the laboratory. Even failure situations which would normally not be feasible for real vehicle test can be tested in the simulator.