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Technical Paper

Effects of Road Structure and Buffer Building on Reduction of Road Traffic Noise

1989-11-01
891304
In order to investigate the possibility of noise countermeasures taken on the road and in its surroundings an urban area exposed to high road traffic noise level was taken up as a model, and their effectiveness was estimated by a hybrid simulation method combining a scale model experiment technique and a computer simulation. The case studies of simulation were carried out in the case of improving the road structures, laying the noise barriers, constructing the noise-buffer buildings and so on. As a result, more than 20 dB (A) of road traffic noise reduction were obtained by a modification of the existing surface road to an elevated road.
Technical Paper

Thermal Behavior in Hydrogen Storage Tank for FCV on Fast Filling (2nd Report)

2008-04-14
2008-01-0463
If a compressed hydrogen tank for vehicles is filled with hydrogen gas more quickly, the gas temperature in the tank will increase. In this study, we conducted hydrogen gas filling tests using the TYPE 3 and TYPE 4 tanks. During the tests, we measured the temperature of the internal liner surface and investigated its relationship with the gas temperature in the tank. We found that the gas temperature in the upper portion of the TYPE 4 tank rose locally during filling and that the temperature of the internal liner surface near that area also rose, resulting in a temperature higher than the gas temperature at the center of the tank. To keep the maximum temperature in the tank below the designed temperature (85°C) during filling and examine the representative tank internal temperatures, it is important to examine filling methods that can suppress local rises of tank internal temperature.
Journal Article

An Experimental Study on the Fire Response of Vehicles with Compressed Hydrogen Cylinders

2010-04-12
2010-01-0134
To investigate the events that could arise when fighting fires in vehicles with carbon fiber reinforced plastic (CFRP) hydrogen storage cylinders, we conducted experiments to examine whether a hydrogen jet diffusion flame caused by activation of the pressure relief device (PRD) can be extinguished and how spraying water influences the cylinder and PRD. The experiments clarified that the hydrogen jet flame cannot be extinguished easily with water or dry powder extinguishers and that spraying water during activation of the PRD may result in closure of the PRD, but is useful for maintaining the strength of CFRP composite cylinders for vehicles.
Technical Paper

Fire Safety Evaluation of a Vehicle Equipped with Hydrogen Fuel Cylinders: Comparison with Gasoline and CNG Vehicles

2006-04-03
2006-01-0129
In this study, we evaluated the fire safety of vehicles that use compressed hydrogen as fuel. We conducted fire tests on vehicles that used compressed hydrogen and on vehicles that used compressed natural gas and gasoline and compared temperatures around the vehicle and cylinder, internal pressure of the cylinder, irradiant heat around the vehicle, sound pressure levels when the pressure relief device (PRD) was activated, and damage to the vehicle and surrounding flammable objects. The results revealed that vehicles equipped with compressed hydrogen gas cylinders are not more dangerous than CNC or gasoline vehicles, even in the event of a vehicle fire.
Technical Paper

Development of Fuel Consumption Measurement Methods for Hydrogen Fuel Cell Vehicles

2006-04-03
2006-01-0217
Japan Automobile Research Institute has devised and evaluated the various fuel consumption measurement methods for fuel cell vehicles (FCVs). The examination covers the methods based on measurement of electrical current, hydrogen pressure/temperature, weight and flow rate that are expected to be the same accuracy and convenience as conventional measurement methods such as carbon balance method or fuel flow measurement method. As a result of examining the measurement accuracy for each method with a sonic nozzle used as a standard, it is found that both the pressure method and the weight method fulfill the target accuracy of ±1% and that the flow method is able to improve the accuracy by means of calibration with hydrogen. Also, as a result of applying each method to the fuel consumption test of FCVs, the relative error between the pressure method and weight method is within ±1%.
Technical Paper

Diffusion and Ignition Behavior on the Assumption of Hydrogen Leakage from a Hydrogen-Fueled Vehicle

2007-04-16
2007-01-0428
hydrogen was leaked from the underfloor at a flow rate exceeding 131 NL/min (11.8 g/min), which is the allowable fuel leakage rate at the time of a collision of compressed hydrogen vehicles in Japan, and the resulting distribution of concentration in the engine compartment and the dispersion after stoppage of the leak were investigated. Furthermore, ignition tests were also conducted and the impact on the surroundings (mainly on human bodies) was investigated to verify the safety of the allowable leakage rate. The tests clarified that if hydrogen leaks from the underfloor at a flow rate of 1000 NL/min (89.9 g/min) and is ignited in the engine compartment, people around the vehicle will not be seriously injure. Therefore, it can be said that a flow rate of 131 NL/min (11.8 g/min), the allowable fuel leakage rate at the time of a collision of compressed hydrogen vehicles in Japan, assures a sufficient level of safety.
Technical Paper

Large Eddy Simulation of Unsteady Flow Around a Formula Car on Earth Simulator

2007-04-16
2007-01-0106
One of the world's largest unsteady turbulence simulations of flow around a formula car was conducted using Large Eddy Simulation (LES) on the Earth Simulator in Japan. The main objective of our study is to investigate the validity of LES for the assessment of vehicle aerodynamics, as an alternative to a conventional wind tunnel measurement or the Reynolds Averaged Navier-Stokes (RANS) simulation. The aerodynamic forces estimated by LES show good agreement with the wind tunnel data (within several percent!) and various unsteady flow features around the car is visualized, which clearly indicate the effectiveness of large-scale LES in the very near future for the computation of flow around vehicles with complex configurations.
Technical Paper

Impact Study of High Biodiesel Blends on Performance of Exhaust Aftertreatment Systems

2008-10-06
2008-01-2494
Biodiesel Fuel (BDF) Research Work Group works on identifying technological issues on the use of high biodiesel blends (over 5 mass%) in conventional diesel vehicles under the Japan Auto-Oil Program started in 2007. The Work Group conducts an analytical study on the issues to develop measures to be taken by fuel products and vehicle manufacturers, and to produce new technological findings that could contribute to the study of its introduction in Japan, including establishment of a national fuel quality standard covering high biodiesel blends. For evaluation of the impacts of high biodiesel blends on performance of diesel particulate filter system, a wide variety of biodiesel blendstocks were prepared, ranging from some kinds of fatty acid methyl esters (FAME) to another type of BDF such as hydrotreated biodiesel (HBD). Evaluation was mainly conducted on blend levels of 20% and 50%, but also conducted on 10% blends and neat FAME in some tests.
Technical Paper

Development of Simulation Model and Pedestrian Dummy

1999-03-01
1999-01-0082
Honda has been studying ways of improving vehicle design to reduce the severity of pedestrian injury. Full-scale test using a pedestrian dummy is an important way to assess the aggressiveness of a vehicle to pedestrians. However, from test results it is concluded that current pedestrian dummies have stiffer characteristics than Post Mortem Human Subjects (PMHS). Also, the dummy kinematics during a collision is different from that of a human body. Because of the limitations of current dummies, it was decided to develop a new pedestrian dummy. At the first stage of the project, a computer simulation model that represented the PMHS tests was developed. Joint characteristics obtained from the simulation model were used in building a new pedestrian dummy which has been named Polar I. The advanced frontal crash test dummy, known as Thor, was selected as the base dummy. Modifications were made for the thorax, spine, knee etc.
Technical Paper

Development and Verification of a Computer Simulation Model of Motorcycle-to-Vehicle Collisions

1999-03-01
1999-01-0719
In order to establish a systematic approach to the study on the injuries sustained by motorcycle riders in accidents and the assessment of protective devices fitted to motorcycles, this research develops a computer simulation model of motorcycle-to-vehicle collision model based on multibody kinematics and dynamics using MADYMO (MAthematical DYnamic MOdel). The effectiveness of the motorcycle-to-vehicle crash model is verified using data of 14 full-scale tests. Comparisons between the simulation peak head acceleration results and the full-scale crash tests data demonstrate a satisfactory agreement between them. The simulation results along with the test data indicate that the leg protectors fitted to the motorcycle can induce harmful consequences to the rider head in some configurations, regardless of their aimed protective effects on the rider’s legs. The findings obtained in this study also provide basis for further improvement of the current model.
Technical Paper

Japan Clean Air Program (JCAP): Preliminary Modeling Study of Vehicle Emission Impacts on Air Quality

1999-05-03
1999-01-1482
Comparing with the previous Auto/Oil programs, the total plan and current status of the air quality modeling study in JCAP are presented. The total plan of air quality modeling study has the following characteristics: 1) Vehicle emission inventory program is developed by considering the original features of Japan. 2) Not only the urban air quality but also the road sides pollutants dispersion is evaluated. 3) The chemical reaction model for the secondary particulate formations is developed on the basis of the smog chamber experiments. 4) For the cost-effectiveness analysis of vehicle/fuel technologies, the output of the air quality modeling will be combined with the cost data of new vehicle emission reduction technologies As the first step, preliminary modeling studies are conducted to understand the overall tendency of the air quality change toward 2010 in Tokyo urban area.
Technical Paper

Validity of Low Ventilation for Accident Processing with Hydrogen Leakage from Hydrogen-Fuelled Vehicle

2013-04-08
2013-01-0211
Appropriate emergency response information is required for first responder before hydrogen fuel cell vehicles will become widespread. This paper investigates experimentally the hydrogen dispersion in the vicinity of a vehicle which accidentally releases hydrogen horizontally with a single volumetric flow of 2000 NL/min in the under-floor section while varying cross and frontal wind effects. This hydrogen flow rate represents normally a full throttle power condition. Forced wind was about maximum 2 m/s. The results indicated that the windward side of the vehicle was safe but that there were chiefly two areas posing risks of fire by hydrogen ignition. One was the leeward side of the vehicle's underbody where a larger region of flammable hydrogen dispersion existed in light wind than in windless conditions. The other was the area around the hydrogen leakage point where most of the leaked hydrogen remained undiffused in an environment with a wind of no stronger than 2 m/s.
Technical Paper

Methanol Lean Burn in an Auto-Ignition DI Engine

1998-02-23
980531
A new combustion system targeting a drastic decrease in NOx emission and a brake specific energy consumption equivalent to that of a DI diesel engine has been developed. In this new combustion system, a lean burn system using early injection was employed to reduce NOx emission and an auto-ignition DI engine system was employed to achieve the low energy consumption. Methanol was used as the fuel for reducing NOx emission. The objective of this study is to clarify the possibility of the system for the auto-ignition of a premixed lean mixture of methanol fuel. This study shows that the gas temperature at ignition, Tig, is the predominant factor affecting auto-ignition. Auto-ignition occurs when Tig exceeds approximately 1000K. The methanol lean burn system in an auto-ignition DI engine drastically decreased NOx emission with almost the same brake specific energy consumption as a diesel engine in the middle load region.
Technical Paper

A Simulation Analysis of Human Cervical Spine Motion During Low Speed Rear-End Impacts

2000-03-06
2000-01-0154
The non-physiological motions of human cervical vertebrae were analyzed in volunteer tests for rear-end impacts and were considered to be an important parameter for neck injuries. The objectives of this study are to improve the Marko de Jager neck model using volunteer test data and to analyze the influence of horizontal and vertical accelerations on cervical vertebral motion. In the beginning of this study, a neck model was positioned based on X-ray cineradiography of a volunteer. Motions of each vertebra were compared with those of volunteer test data for low speed rear-end impacts (4, 6, 8km/h). In these comparisons, the differences of vertebrae motions between the neck model and the volunteer tests were found. To improve the validity of the neck model, the connection properties and the bending properties of the upper and lower vertebrae of the model were modified to increase rigidity.
Technical Paper

Research on bus passenger safety in frontal impacts

2001-06-04
2001-06-0210
Guidelines with regard to the body strength of buses have been drawn up in Japan. We now pass to the second step in research to assure the greater safety of bus crews and passengers by launching a study on further reduction of collision injuries to bus occupants. As a way to reduce such passenger injuries, our focus is the optimization of energy absorption, the arrangement of equipment on the passenger seat back, the seat frame construction, mounting and so on. The study was conducted using an experimental method together with FEM computer simulation. The findings from a sled impact test simulating a seat in a bus in a frontal collision are stated as follows. 1.Further consideration should be given to the present conventional ELR two-point seat belt. 2.One way to reduce passenger injury is to optimize the space between seats.
Technical Paper

Safety Evaluation on Fuel Cell Stacks Fire and Toxicity Evaluation of Material Combustion Gas for FCV

2007-04-16
2007-01-0435
Fuel cell vehicles represent a new system, and their safety has not yet been fully proved comparing with present automobile. Thorough safety evaluation is especially needed for the fuel system, which uses hydrogen as fuel, and the electric system, which uses a lot of electricity. The fuel cell stacks that are to be loaded on fuel cell vehicles generate electricity by reacting hydrogen and oxygen through electrolytic polymer membranes which is very thin. The safety of the fuel and electric systems should also be assessed for any abnormality that may be caused by electrolytic polymer membranes for any reasons. The purpose of our tests is to collect basic data to ultimately establish safety standards for fuel cell stacks. Methanol pool flame exposure tests were conducted on stationary use fuel cell stacks of two 200W to evaluate safety in the event of a fire.
Technical Paper

Evaluation of Regulated Materials and Ultra Fine Particle Emission from Trial Production of Heavy-Duty CNG Engine

2006-10-16
2006-01-3397
A prototype CNG engine for heavy-duty trucks has been developed. The engine had sufficient output in practical use, and the green-house gas emission rate was below that of the base diesel engine. Furthermore, the NOx emission rate was reduced to 0.16 g/kWh in the JE05 mode as results of having fully adjusted air fuel ratio control. The measured emission characteristics of particles from the prototype CNG engine demonstrated that oil consumption was related to the number of particles. Moreover, when oil consumption is at an appropriate level, the accumulation mode particles are significantly reduced, and the nuclei mode particles are fewer than those of diesel-fueled engines.
Journal Article

Development of an Unsteady Aerodynamic Simulator Using Large-Eddy Simulation Based on High-Performance Computing Technique

2009-04-20
2009-01-0007
A numerical method specially designed to predict unsteady aerodynamics of road vehicle was developed based on unstructured Large-Eddy Simulation (LES) technique. The code was intensively optimized for the Earth Simulator in Japan to deal with the excessive computational resources required for LES, and could treat numerical meshes of up to around 120 million elements. Moving boundary methods such as the Arbitrary Lagrangian-Eulerian (ALE) or the sliding method were implemented to handle dynamic motion of a vehicle body during aerodynamic assessment. The method can also model a gusty crosswind condition. The method was applied to three cases in which unsteady aerodynamics are expected to be crucial.
Journal Article

Developing Safety Standards for FCVs and Hydrogen Vehicles

2009-04-20
2009-01-0011
The SAE Fuel Cell Vehicle (FCV) Safety Working Group has been addressing FCV safety for over 9 years. The initial document, SAE J2578, was published in 2002. SAE J2578 has been valuable as a Recommended Practice for FCV development with regard to the identification of hazards and the definition of countermeasures to mitigate these hazards such that FCVs can be operated in the same manner as conventional gasoline internal combustion engine (ICE)-powered vehicles. SAE J2578 is currently being revised so that it will continue to be relevant as FCV development moves forward. For example, test methods were refined to verify the acceptability of hydrogen discharges when parking in residential garages and commercial structures and after crash tests prescribed by government regulation, and electrical requirements were updated to reflect the complexities of modern electrical circuits which interconnect both AC and DC circuits to improve efficiency and reduce cost.
Journal Article

Developing Safety Standards for FCVs and Hydrogen Vehicles

2008-04-14
2008-01-0725
The SAE FCV Safety Working Group has been addressing fuel cell vehicle (FCV) safety for over 8 years. The initial document, SAE J2578, was published in 2002. SAE J2578 has been valuable to FCV development with regard to the identification of hazards and the definition of countermeasures to mitigate these hazards such that FCVs can be operated in the same manner as conventional gasoline internal combustion engine (ICE)-powered vehicles. J2578 is currently being updated to clarify and update requirements so that it will continue to be relevant and useful in the future. An update to SAE J1766 for post-crash electrical safety was also published to reflect unique aspects of FCVs and to harmonize electrical requirements with international standards. In addition to revising SAE J2578 and J1766, the Working Group is also developing a new Technical Information Report (TIR) for vehicular hydrogen systems (SAE J2579).
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