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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Automotive Engineers
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Journal DOI :
The Korean Society of Automotive Engineers
Editor in Chief :
Volume & Issues
Volume 11, Issue 6 - Nov 2003
Volume 11, Issue 5 - Sep 2003
Volume 11, Issue 4 - Jul 2003
Volume 11, Issue 3 - May 2003
Volume 11, Issue 2 - Mar 2003
Volume 11, Issue 1 - Jan 2003
Selecting the target year
Experimental Study of the Effect of Secondary Air Injection on the Cold Start Total Hydrocarbon Emissions in a Spark Ignition Engine
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 1~6
Engine emission regulations are becoming more stringent nowadays. In cold transient regime, about 80% THC is exhausted to the atmosphere in the first 200s (US FTP cycles). Accordingly, reducing emission levels in the cold period immediately after the engine start before the catalysts reach their working temperature will be an especially critical factor in meeting more stringent regulations in the future. In this study, the total hydrocarbon quantities are measured using a Fast FID with gasoline fuel for a 4-cylinde. Sl engine, including Secondary Air Injection (SAI) system. Commercial SAI device's direction is reverse to the exhaust flow. In this study, a swirl flow type SAI system which is positioned between the exhaust manifold and exhaust port, was developed. We compared the swirl type secondary air injection with a commercial secondary air injection of .everse flow. The swirl type SAI showed better results in reducing HC by 26% than the commercial flow type SAI of reverse flow which was caused by the better mixing between the exhaust gas and the secondary air.
Engine Modeling and Validation for Control System Design of a Gaseous-fuel Engine
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 7~17
Highly accurate control of an air-fuel ratio is very important to reduce exhaust gas emissions of gaseous-fuel engines. In order to achieve this purpose, a precise engine model is required to estimate engine performance from the engine design process which is applied to the design of an engine controller. Engine dynamics are considered to develop a dynamic engine model of a gaseous-fuel engine. An effective air mass ratio is proposed to study variations of the engine dynamics according to the water vapor and the gaseous-fuel in the mixture. The dynamic engine model is validated with the LPG engine under steady and transient operating conditions. The experimental results in the LPG gaseous-fuel engine show that the estimation of the air flow and the air-fuel ratio based upon the effective air mass ratio is more accurate than that of a normal engine model.
A Study on the Driving Patterns for Passenger Car in the Metropolitan Area
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 18~24
Vehicle emission is one of the major sources of air pollution, and provides some undesirable effects on the atmospheric environment and human health. In this study, the driving data were recorded during road tests in Seoul metropolitan wet and analyzed by statistical techniques. The objective of the study is to analyze the driving Patterns of passenger car that influence on emissions in urban driving. The results show that the average speed is around 29.2 km/h, and the average fuel economy is 10.23 km/
. The vehicle speed of Seoul metropolitan area is slower, and the stop-and-go operation is more frequent than CVS-75 test mode which is used far emission and fuel economy test.
A Study on the Fuel Economy based on the Driving Patterns for Passenger Car in the Metropolitan Area
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 25~31
There are a lot of factors influencing on the automobile fuel economy such as average speed, average acceleration, acceleration sum per kilometer, and so on. In this study, various driving data were recorded during road tests. The accumulated road test mileage in Seoul metropolitan area is around 1,300 kilometers. The data were analyzed by multivariate statistical techniques including correlation analysis, principal component analysis, and multiple linear regression analysis. The analyzed results show that the average trip time per kilometer is one of the most important factors to fuel consumption and the increase of the average speed is desirable for reducing emissions and fuel consumption.
Coolant Flow Characteristics and Cooling Effects in the Cylinder Head with Coolant Flow System and Local Water Passage
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 32~41
For the countermeasure of expected higher thermal load in miller cycle engine, coolant flows in the cylinder head of base engine with several coolant flow methods and drilled hole passages were measured by using PIV technique. And the cooling effect was evaluated by measurements of wall temperatures according to each coolant flow method. It was found that the series flow system was most suitable among the discussed 3 types of coolant flow methods since it had the best cooling effect in cylinder head by the fastest coolant flow velocity It was also found that for drilled water passage to decrease the large thermal load in exhaust valve bridge, nozzle type is more effective compared with round type of water passage, and its size has to be determined according to the coolant flow pattern and velocity in each cylinder.
Study on the Estimation of Knock Position in a LPG Engine with Ion-probe Head Gasket
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 42~48
LPG has been a broad concern of pro-environmental alternative fuel for vehicles. Recently, the new Liquid Phase LPG Injection(LPLI) system extends the limit of power of LPG engine and gives a chance to substitute LPG engine for diesel engine of heavy duty vehicles that are the main resources of air pollution in urban area. Large bore size of heavy duty LPG engine derives a serious knock problem. To find an optimal MBT conditions, it is necessary to know how the flame develops in the combustion chamber and find where the knock positions are. In this study. the ion-probe head gasket was used to estimate the knock position. Inverse operation of the ion-probe signal provides the flame developing characteristics. The further the position is from the spark plug, the later the flame arrives and the more times knock occurs. The main factor that effects knock position is inferred a flor situation of mixed gas in the combustion chamber.
Effect of Premixed Fuel on the Combustion Characteristics of Premixed Charge Compression Ignition Engine
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 49~54
The purpose of this work is to investigate the effect of premixed fuel on the reduction of exhaust emissions in premixed charge compression ignition engine. The premixed fuel is injected into the intake manifold to form homogeneous pre-mixture in the combustion chamber. The pre-mixture is ignited by a small amount of diesel fuel directly injected into the cylinder. In the case of gasoline as a premixed fuel of the engine,
and smoke concentration of exhaust emissions were reduced compared with the conventional diesel engine. But in the event of diesel fuel for premixed fuel, the rate of smoke reduction was small compared with the case of gasoline as a premixed fuel. HC and CO emissions were increased at high premixed ratio in the case of two premixed fuels. The combustion characteristics of the engine such as the combustion pressure, the rate of heat release, and other characteristics are compared.
The Flame Characteristics by Combustion Chamber Shape in 2 Stroke D.I. Diesel Engine -The Influence of Scavenging Pressure and Scavenging Temperature-
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 55~63
In a diesel engine, air-fuel mixture formation and ignition delay period have great influence on the performance of engine. Their main factors are combustion chamber shape, fuel injection system. air volume, air flow and so on. So, the combustion process in the cylinder is complex because of many factors which have direct and indirect effects on it. In this study, we take into consideration of scavenging pressure and scavenging temperature that are hewn as the main factor to the combustion process of two-stroke D.1. diesel engine. It is taken a picture of the combustion flame process for combustion chamber of re-entrant type and cylindrical type. So, it is applied to the basis data of combustion chamber design from an image analysis.
A Study on Relationship between Fuel Characteristics and Combustion Characteristics of Reformed Diesel Fuels by Ultrasonic Energy Irradiation (II) - Relationship between Chemical Structure and Cetane Number -
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 64~71
In order to analyze the effect of the chemical structure and the cetane number of reformed diesel fuels by ultrasonic energy irradiation, proton nuclear magnetic resonance spectrometer
was used. From the study, following conclusive remarks can be made. 1) Branch Index(BI), aromatics percentages, and alpha methyl radical
of the reformed diesel fuels by ultrasonic energy irradiation decreased more than the conventional ones. 2) All the cetane numbers which were calculated from carbon type structure and hydrogen type distribution of the reformed diesel fuels increased more than the conventional ones. 3) It is more reasonable to predict cetane number equation from carbon type structure than from hydrogen type distribution. 4) BI, aromatics percentages, and
on both for conventional fuel and reformed diesel fuels by ultrasonic energy irradiation are inversely proportional to cetane number fur these fuels.
The Combustion Characteristics of Biodiesel Fuel as an Alternative Fuel for IDI Diesel Engine
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 72~78
Recently, lots of researchers have been attracted to develope various alternative fuels and to use renewable fuels as a solution of environmental problems from automobile. The use of biodiesel fuel is an effective way of substituting diesel fuel in the long nun. It is a domestically produced, renewable fuel that can be manufactured from vegetable oils, used vegetable oils, or animal fats. In this study, the usability of biodiesel fuel derived from rice ban oil, one of the oxygenated fuels as an alternative fuel for diesel engines was investigated in IDI diesel engine. Emissions were characterized with neat biodiesel fuel and with a blend of biodiesel fuel and conventional diesel fuel. Since the biodiesel fuel includes oxygen of about 11%, it could influence the combustion process strongly. So, the use of biodiesel fuel resulted in lower emissions of carbon monoxide and smoke emissions with some increase in emissions of oxides of nitrogen. It is concluded that biodiesel fuel can be utilized effectively as a renewable fuel for IDI diesel engine.
The Effect of Cooled EGR and Oxygenate Fuel(EGBE) on the Diesel Engine Performance and Emissions
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 79~86
In this paper, the effect of oxygen component in fuel on the exhaust emissions has been investigated fur direct injection diesel engine. It was tested to estimate change of engine performance and exhaust emission characteristics for the commercial diesel fuel and oxygenated blended fuel which has seven kinds of mixed ratio. And, the effects of exhaust gas recirculation(EGR) on the characteristics of NOx emission have been investigated. Ethylene glycol mono-n-butyl ether(EGBE) contains oxygen component 27% in itself, and it is a kind of effective oxygenated fuel of mono-ether group that the smoke emission and unburned hydrocarbons of EGBE is reduced remarkably compared with commercial diesel fuel, that is, it can supply oxygen component sufficiently at higher loads and speeds in diesel engine. It was found that simultaneous reduction of smoke and NOx was achieved with oxygenated fuel and cooled EGR method.
A Study on the Development of Icing by Injection of LPG in the Liquid Phase around Injector (I)
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 87~94
Recently, LPLi(Liquied-Phase LPG injection) system is studied for the new stringent emission regulations. But , there are some problems to be solved such as injector tip icing and fuel leakage for LPLi system development. In this paper, the icing problem near injector tip which leads to difficulty of accurate A/F control was studied and reported. Icing of injector tip and port wall was observed at all the cases in this study regardless of injection duration and angle, air humidity change. The spray angle of LPLi was observed approximately two times wider than that of Gasoline injection. This makes the LPLi spray collide with intake port around injector tip. Temperature of the wetted area was decreased and icing of water vapor contained in intake air because of evaporation of the fuel film. The ice of the injector tip and port wall is also affected by the materials related to heat transfer.
A Study on Modeling and Fault Diagnosis of Suspension Systems Using Neural Network
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 95~103
Driving safety of a vehicle is largely influenced by the damper and the tire. Developed in this research is a fault diagnosis algorithm for the two components so that the driver can be promptly informed when fault occurs in one or both of them. To this end, the damper and the tire were modeled using the neural network from their experimental data, and fault diagnosis was made using frequency responses of the damping force and the dynamic wheel force. The algorithm was tested via experiments, and it demonstrated successful diagnostic performance under various driving conditions.
A Study on the Nonlinear Dynamic Modeling and Analysis of Damping Force Characteristics of Automotive Shock Absorber
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 104~111
The performance of shock absorber is directly related to the car behaviour and performance, both for handling and comfort. In this study, a mathematical nonlinear dynamic model and computational method are introduced to study the flow and performance of shock absorber. The flow characteristics of components(piston and body valve) are investigated and applied to dynamic modeling of shock absorber to predict the damping force. The simulation results agree with the test data well. The shock absorber model proposed in this paper is applicable as a part of a full vehicle suspension simulation.
Characteristics of Dynamic Track Tension for Three Dimensional High Mobility Tracked Vehicle
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 112~120
In this paper, dynamic track tension fur high mobility tracked vehicle is investigated by multibody dynamic simulation techniques. This research focuses on a heavy military tracked vehicle which has sophisticated suspension and rubber bushed rack systems. In order to obtain accurate dynamic track tension of track subsystems, each track link is modeled as a body which has six degrees of freedom. A compliant bushing element is used to connect track links. Various virtual proving ground models are developed to observe dynamic changes of the track tension. Numerical studies of the dynamic track tension are validated against the experimental measurements. The effects of pre-tensions, traction forces, fuming resistances, sprocket torques, ground profiles, and vehicle speeds, for dynamic responses of track tensions are explored, respectively.
Development of a Measurement System of Torsional and Conical Suspension Bushing Rates with the Flexible Jig
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 121~127
The stiffness of a bushing in a suspension is extremely important for the overall performance of the suspension system. A new measurement system including the flexible jig was developed to measure the multi-directional stiffness of bushings. To overcome the disadvantage of building each individual jig for each type and size of a bushing, we designed the flexible jig which can accommodate numerous bushings of similar shapes and sizes. Upon using the novel design of the flexible jig in the industry, we could successfully measure the torsional and conical stiffness of many bushings and apply the data for the prediction and evaluation of the performance of a suspension system, which would assist designing the optimal suspension system.
A Study on Improvement of Crash Discrimination Performance for Offset and Angular Crash Events Using Electronic X-Y 2-Axis Accelerometer
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 128~136
In today's design trend of vehicle structure, crush zone is fiequently reinforced by adding a box-shaped sub-frame in order to avoid an excessive deformation against a high-speed offset barrier such as EU Directive 96/97 EC, IIHS offset test. That kind of vehicle structure design results in a relatively monotonic crash pulse for airbag ECU(Electronic Control Unit) located at non-crush zone. As for an angular crash event, the measured crash signal using a single-axis accelerometer in a longitudinal direction is usually weaker than that of frontal barrier crash. Therefore, it is not so easy task to achieve a satisfactory crash discrimination performance for offset and angular crash events. In this paper, we introduce a new crash discrimination algorithm using an electronic X-Y 2-axis accelerometer in order to improve crash discrimination performance especially for those crash events. The proposed method uses a crash signal in lateral direction(Y-axis) as well as in longitudinal direction(X-axis). A crash severity measure obtained from Y-axis acceleration is used to improve the discrimination between fire and no-fire events. The result obtained by the proposed measure is logically ORed with an existing algorithm block using X-axis crash signal. Simulation and pulse injection test have been conducted to verify the performance of proposed algorithm by using real crash data of a 2,000cc passenger vehicle.
Axisymmetric Temperature Analysis of Ventilated Disk using Equivalent Parameters
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 137~142
In automotive brake systems, the frictional heat generated can cause high temperature at the interface of rotor and pad which may deteriorate the material properties of the sliding parts and can result in brake fade. Conventionally, a pie-shaped 3-dimentional model is adopted to calculate temperature of ventilated disk using finite element method. To overcome the difficulties in preparing 3D finite element model and reduce the computational time required, the ventilated rotor is to be analyzed, in this study, as an axisymmetric finite element model in which, taking into considerations the effects of cooling passages, a homogenization technique is used to obtain the equivalent thermal properties and boundary conditions for the elements placed at the vent holes. Numerical tests show the proposed procedure can be successfully applied in practice, replacing 3-dimensional thermal analysis of ventilated disk.
Fatigue Characteristics of SPFC590 Laser Welded Sheet Metal for Automobile Body Panel
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 143~150
Experimental research has been carried out to investigate the characteristics of the fatigue crack initiation and propagation behavior of Tailor Welded Blank(TB) sheet used for vehicle body. We used three types of specimens which were machined of the same base metal: one is 1.4mm thick, another is 1.6mm thick, and the third(TB specimen) is laser-welded of two specimens(1.4mm and 1.6mm thick ones). The results of tensile and hardness test indicate that the yield strength of the TB specimen is the highest, and the hardness around welding bead is higher than that of base metal. Fatigue strength and fatigue limit of the TB specimen are much superior to those of the base metal up to
cycles. The fatigue crack propagation of the heat-affected zone of the TB specimen is slower than that of the base metal. Welding bead has the fastest crack Propagation in the low stress intensity factor range
region, but the slowest in the high
region. The fatigue propagation characteristic of the TB specimen is relatively stable in comparison with that of the base metal in the high
region around over
Design of a Composite Propeller Shaft with the Reduced Weights and Improved NVH
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 151~159
The front 2 pieces of the 3-piece steel propeller shaft installed on a 8.5-ton truck were redesigned with a 1 -piece composite propeller shaft with steel yokes and spline parts to get the reduction of weight and the improvement of NVH characteristics. Based on the analysis of bending vibration, strength and cure-induced residual stresses of the composite propeller shaft, proper composite materials and stacking sequences were selected. The composite propeller shaft requires a reliable joining method between the shaft and steel end parts through a steel connector. From 3-D contact stress analyses of the laminated composite shaft with bolted Joints, the 3-row mechanical joint which satisfies the torque transmission capability has been designed. Several full-scale composite shafts were fabricated and tested to verify the design analyses. The design requirements are shown to be satisfied. With the newly designed composite shaft, the weight reduction more than 50% and improvements in NVH characteristics have been achieved.
Development of a Rapid Control Prototyping Platform for Engine Control System
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 160~165
The design and implementation of an engine control system has become an important area in developing a new car, but the implementation of an engine control system is becoming a tedious and time-consuming work as the level of complexity increases. In order to shorten the development cycle of the control system, rapid control prototyping (RCP) technique deserves developers' attention. A new RCP platform has been developed for an automotive engine control application. This prototyping system strictly adheres to the layered architecture of the final production ECU, and separates the automatically generated part of software, or the application area, from the hand coded area, which generally carefully designed and tested because of the hardware dependency and the efficiency of microcontroller. The
tool-chain of Mathworks Inc. has been selected as a base environment in this study. A newly developed Engine Control Toolbox of Real-Time
converts a graphically represented control algorithm into optimized application codes and links them with other parts of the software to generate executable code for the target processor.
A Co-simulation Toolbox for Distributed Real-Time Control System
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 166~171
This paper presents the algorithms and Matlab Toolbox for co-simulation of distributed real-time control system based on OSEK-OS and CAN protocol. This toolbox enables the developers to analyze the timing uncertainty, which is caused by resource sharing including shared memories and networks, and to take the timing uncertainty into consideration in the early design phase. Furthermore, this toolbox helps the developers to model the behaviors of a control system by providing graphical user interface for objects of OSEK-OS and CAN. To prove the feasibility of this toolbox, a vehicle body network system is modeled with this toolbox, and the timing uncertainties are analyzed.
The Analysis and Optimization far the Braking System in Electric Vehicle
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 172~178
Driving range is one of the main problems in development of Electric Vehicles(EV). The Regenerative. braking system is required to overcome the problem, which converts kinetic energy of the vehicle during braking into electrical energy. This paper discusses the braking system of EV and Robust design especially developed to maximize energy recovery and to optimize braking performance. This is promised to be applied to the design of elements for EV braking system.
A Study on The Estimation of Effective Bulk Modulus of Hydraulic Oil With Pressure Variation
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 179~184
It has been recognized that the compressibility of hydraulic fluid, which is characterized by the value of its bulk modulus, heavily affects on the system behavior and performance. In practice, the value of the oil bulk modulus varies by the operational and structural characteristics of the hydraulic system. This study presents the theoretical derivation of the effective bulk modulus and describes an experimental impulse technique that allows accurate measurement of oil effective bulk modulus with pressure variation in a hydraulic system. Experimental and analytical results show that the value of the effective bulk modulus varies a lot in low pressure region by the effect of entrained air, while the effective bulk modulus can be estimated just using the oil and container bulk modulus on the other high pressure region.
The Effect of Compressive Residual Stresses of Two-stage Shot Peening far Fatigue life of Vehicle Spring Steel
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 185~192
Recently the steel parts used at automobiles are required to be used under high stress more than ever before in need of the weight down. To achieve this requirement of a high strength steel, it must be necessary to decrease inclusion content and surface defect as like decarburization, surface roughness etc.. In this study, the surface conditions are measured to Dow the influence on fatigue properties by two cases of shot peening of two-stage shot peening and single-stage shot peening. And for this study, three kinds of spring steel (JISG4081-SUP7, SAE 9254, DON 50CrV4) are made. This study shows the outstanding improvement of fatigue properties at the case of two-stage shot peening in the rotary bending fatigue test and this is assumed to be from (1) Decreasing the surface roughness (2) Unchanging the surface hardness (3) Increasing the compressive residual stress. But, results also show fatigue failures originated at inclusion near surface, and this inclusion type is turned out to be a alumina of hish hardness.
The Detection of the Lane Curve using the Lane Model on the Image Coordinate Systems
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 193~200
This paper proposes a novel algorithm to recognize the curve of a structured road. The proposed algorithm uses an LCF (Lane Curve Function) obtained by the transformation of a parabolic function defined on world coordinate into image coordinate. Unlike other existing methods, the algorithm needs no transformation between world coordinate and image coordinate owing to the LCF. In order to search for an LCF describing the lane best, the differential comparison between the slope of an assumed LCF and the phase angle of edge pixels in the LROI (Lane Region Of Interest) constructed by the LCF is implemented. As finding the true LCF, the lane curve is determined. The proposed method is proved to be efficient through various kinds of images, providing the reliable curve direction and the valid curvature compared to the real road.
Intensity Gradients-based Stereo Matching of Road Images
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 201~210
In this paper, we propose a new binocular stereo correspondence method by maximizing a fitness formulated by integrating two constraints of edge similarity and disparity smoothness simultaneously. The proposed stereopsis focusing to measure distances to leading vehicles on roads uses intensity gradients as matching attribute. In contrast to the previous work of area-based stereo matching, in which matching unit is a pixel, the matching unit of the proposed method becomes an area itself which is obtained by selecting a series of pixels enclosed by two pixels on the left and right boundaries of an object. This approach allows us to cope with real-time processing and to avoid window size selection problems arising from conventional area-based stereo.
Developing the LMS Model for Frontal Offset Impact Analysis
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 211~216
A frontal offset impact model Oat can simulate the 40% offset frontal impact into deformable barrier regulated in EU Directive 96/79 EC has been developed. Engine rotation effects are also considered in the model. Distributed 11 masses and characteristics of 23 nonlinear springs comprising the model are determined based on both the stick-model analysis under the general specification of car and the dynamic characteristics of car structure. It is demonstrated that simulated acceleration-time curve for passenger part is in good agreement with test data obtained by NHTSA.
Numerical Study of the Design Factors for Flow Analysis of the Automotive Defrost Nozzle
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 217~224
The frost and mist in the windshield disturb the sight of driver and passengers especially in winter. This possibly leads to safety problems. In order to export automobiles to the countries of North America, the safety regulation requires the frost of selected area should be completely melted in 30 minutes. The defrost pattern and time for melting of frost are fully dependent on the flow and temperature field near the windshield. Furthermore, the flow and temperature field near the windshield are dependent on the air discharged from defrost nozzle. The present work has been done for understanding the flow features of the discharged air and internal flow within the nozzle duct. The three dimensional Navier-Stokes code was used for performing the generic A/C duct flow analysis. The present results were nearly coincided with experimental data. To perform the parametric study of the effectiveness of the number of guide vanes, the discharge angle and the location of nozzle were changed. The ratio of volume flow rate through defrost nozzle and side exit were compared to investigate the influence of parameters on the effectiveness of defrost nozzle. The velocity profiles and flow patterns of the defrost nozzle duct were also analyzed.
Shape Optimization of Cut-Off in a Multi-blade Fan/Scroll System Using Response Surface Method
Transactions of the Korean Society of Automotive Engineers, volume 11, issue 1, 2003, Pages 225~231
In order to improve efficiency of a system with three-dimensional flow characteristics, this paper presents a new method that overcomes three-dimensional effects by using two-dimensional CFD and response surface method. The method was applied to shape optimization of cut-off in a multi-blade fan/scroll system. As the entrance conditions of two-dimensional CFD, the experimental values at the positions out of the inactive zone were used. In order to examine the validity of the two-dimensional CFD the distributions of velocity and pressure obtained by two-dimensional CFD were compared with those of three-dimensional CFD and experimental results. It was found that the distributions of velocity and pressure show qualitatively similarity. The results of two-dimensional CFD were used for constructing the objective function with design variables using response surface method. The optimal angle and radius of cut-off were determined as
and 0.092 times the outer diameter of impeller, respectively. It is quantified the previous report that the optimal angle and radius of cut-off are approximately
and 0.08 times the outer diameter of impeller, respectively.