The numerical procedure for hydroplaning was developed by considering the following three important factors; fluid/structure interaction, tire rolling, and practical tread pattern. The tire is analyzed by FEM with Lagrangian formulation and the fluid is analyzed by FVM with Eulerian formulation. Since the tire and the fluid are modeled separately and their coupling is automatically computed by the coupling element, the fluid/structure interaction of the complex geometry such as the tire with the tread pattern can be analyzed practically. The predictability was validated by comparing the hydroplaning simulation with the experiment on the subjects such as the water flow, the velocity dependence of hydroplaning, and the effect of the tread pattern on hydroplaning. In order to predict the streamline in the contact patch, the procedure of the global-local analysis was developed. The predicted streamline enabled us to develop the new tire pattern in a short period based on the principle; “make the stream line smooth”.

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The rugged surface produced by the nanoparticle coating on a substrate is very effective to prevent water adhesion and maintain the transparent. So, we developed the novel water repellent using nanoparticle for side mirror of a car. The rugged surface by coating is also very effective to prevent powder adhesion too. It was experimentally confirmed to prevent dust adhesion by covering the surface of the glass substrate with nanoparticle. The adhesion force between particle and substrate is measured by the centrifugal method and the relation between the adhesion force and the surface roughness is discussed from experimental and theoretical point of view. The measured and calculated results by Van der Waals force show that adhesion force decreased with the increment of the surface roughness. From the results, nanoparticle coating is very effective to prevent the dust adhesion on the substrate and the various application of nanoparticle coating can be expected.

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In recent years, improvement of fuel consumption efficiency of transport machines have been desired including the vehicles, trucks and construction machines in relation to recent environmental energy issue. Especially, in the construction machines, the power supplied by diesel engine is transferred through the hydraulic system and the working oil with high-pressure flows in hydraulic piping. The energy loss of construction machines caused on hydraulic piping is estimated about 5% or more of total power source, there is some room here for fuel consumption improvement. This paper shows the research on drag reduction in hydraulic piping focusing the Toms effect.

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From ancient times fire has been extinguished mainly by using water. But there may be some problems in large amount of water discharge against fire, such as enough water volume for fire extinguishing may not be secured in case of large-scale natural disasters, and also secondary damage may be caused by discharged water. CAFS, one of fire extinguishing method by using air foam, is the solution because it utilizes small amount of water very efficiently. This report presents an overview of fire extinguishing with air foam, how to generate it and verification experiments of fire extinguishing effect with CAFS foam in MORITA Corporation.

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In order to extend the HCCI high load operational limit, the effects of the distributions of temperature and fuel concentration on pressure rise rate were investigated through theoretical and experimental methods. The Blowdown Supercharge (BDSC) system and the EGR guide parts are employed simultaneously to enhance thermal stratification inside the cylinder. Also, direct fuel injection system was also used to control the distribution of fuel concentration. As a result, pressure rise rate during high load HCCI operation was successfully reduced with the thermal stratification enhanced by the EGR guide. It is also found that the uniformed fuel concentration distribution generated by a direct fuel injection had less effective to reduce pressure rise rate. Because directly injected fuel into hot EGR gas decreased EGR gas temperature leading to reduce thermal stratification generated by the EGR guide.

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The bubble-jet-type air-lift pump was invented by Sadatomi in order to pump up water and sediments deposited on lake and sea beds by striking water jet with air bubbles. In the present paper, the performance of the pump has been reported. In the experiments, the upriser of the pump was 50 mm I.D. and 5.0 m long. The test sediments were three kinds of spherical particles of different size and density, while the test liquid was 3.0 wt % saltwater in view of the usage in sea. The submergence ratio of the upriser in the water was changed from 0.76 to 0.84, and the air supply rate to the upriser was changed up to 250 l/min while the water rate to the bubble-jet-generator was fixed at 72.0 l/min. In the analysis, Yoshinaga et al.’s model for predicting water and particles discharge rates was modified by incorporating a new correlation of particles flow rate fraction in water-particles mixture. The modified model could predict well the present data as well as our previous data at an efficient pump operation condition irrespective of the differences in the salinity, the particles specifications and the submergence ratio.

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Initial concentration condition effect of particle cross-sectional concentrations of particle suspension two phase flows in a microchannel have been investigated. The cross-sectional capacitances between 12 sensor electrodes have been measured by a high speed multiplexer and multi-layer capacitance measurement technique in order to determine the particle concentration. The polystyrene particles as a solid phase and non-conductive deionized water as a liquid phase are non-uniformly injected into inlets microchannel. The normalized particle concentration was calculated based on the multi-layer capacitance measurement from modified Maxwell equation. The particles are migrated from the upstream to downstream cross-section, particles move away from center streamlines to near the wall vicinity area and the number of the particles migration towards wall vicinity area are clearly increased near to the outlet area. The stream transitional particle migration due to lift forces is investigated with the effect of the initial particle concentration. The results shows the particle migration ratio decreased with the increment of the initial particle concentration where in case of initial particle concentration, ξ=3.0% it shows the higher particle migration ratio from the upstream to downstream cross-section than the initial particle concentration, ξ=5.0 or 10.0%.

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The direct methanol fuel cell is one of the most promising candidates of the next-generation power sources for small electric appliances. However, there still remain some issues, one of which is regarding carbon dioxide bubbles generated in the anode channel. They tend to cover the gas diffusion layer (GDL) surface, obstruct the reaction and deteriorate the overall fuel cell performance. Therefore, it is important to clarify the flow mechanisms of the gas-liquid two-phase flow of methanol solution. In this study, the influence of wettability of the anode channel walls on the fuel cell performance was investigated along with flow visualization and pressure measurements using a special experimental setup. The results showed that a higher and more stable output voltage was obtained in the fuel cell with hydrophobic channel walls. The results also showed that CO₂ bubbles tended to detach from the GDL surface, merge and attach to the hydrophobic channel walls, which probably led to facilitate fuel supply and CO₂ gas emission.

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An experimental investigation is carried out on the effects of a sudden contraction on the characteristics of an air-water two-phase flow in a millimeter-scale rectangular channel. The results reveal that the flow pattern transition types caused by sudden contraction can be basically classified into five. The scatter of the leading edge velocity of a bubble observed downstream of the sudden contraction increases as the channel height becomes smaller than a certain critical value. This phenomenon is not beneficial for practical usage of gas-liquid two-phase flows in micro channels.

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