For the therapeutic application of microbubbles, which are attracting attention in recent years. But the Technology for directing microbubbles to the seat of disease is not established. In this study, we are developing the technique to control microbubbles in flow channel which for simulation of blood flow. We choose electric field which the technique to control microbubbles. We have succeeded to induce microbubbles in flow using various types of flow channel which for simulation of blood flow by electric field.

Surface tension of liquid metal varies in oxide condition for a short time since it is sensitive to surface oxidation. The temporally varying surface tension, i.e. dynamic surface tension, has great impact on many industrial processes relating to liquid metal. In this study, the dynamic surface tension of solder is measured by capillary jet method. Measured results indicate fast decrease from initial value to equilibrium surface tension for 2 - 4ms under the oxygen concentration of around 0.02%.

Molecular dynamics simulations are performed to investigate the static wettability of Lennard-Jones liquid droplets. Argon molecules are also considered as the wall molecules. In this study, we proposed a new method considering the adsorption layers to fit the liquid-vapor interface and calculate the contact angle of the droplet. The result is compared with the conventional method which cutoffs the adsorption layers to avoid the influence of density fluctuations. It is found that the fitting curve from this method shows better agreement with the interface than using the conventional method.

It is known that the number of cavitation bubble nuclei increases exponentially as the degree of superheat of liquid increases. Bubble Nucleation Model is incorporated with general-purpose thermal fluid analysis software STAR-CCM+ which set constant number of bubble nuclei. The influence of the change in the number of bubble nucleus on the bubble collapse energy is verified.

In this study, a cleaning device to remove micron-sized particles on a solid surface by an air jet is developed. This device has a special nozzle containing a triangular cavity to add high intensity turbulence to the air jet. Assuming that the spherical particles are removed by rotational movement, we estimated the rotational moment induced by drag force and local pressure gradient from calculated flow field by numerical simulation. This estimation for various nozzle shapes with different inlet widths revealed that the nozzle with 1.0 mm inlet width gives the best removal performance.

Faced with a changing about global environmental issues, there are great expectations to optimize energy saving design in home appliance products. For effective energy saving design in Refrigeration System, integrated design method is highly needed to understand detailed physical behavior of a whole product based on careful study of the interactive influence of each device (e.g., Insulator layout design, Heat exchanger, Compressor and FAN flow rate balance, etc.). Although 3D-CAD and CAE become a part of engineer's daily routine in recently, effective integrity interface between the Digital tool and real humanistic collaboration process is the most important key to accomplish the innovative synthesis. This paper presents a Lean Product and Process Development for Refrigerator energy saving design.

Nanofibers of polypropylene were produced by modified melt blow method. Its manufacturing method and thermal characteristics of fabricated nonwoven fabric nanofibers were studied. Apparent thermal conductivity was measured as an evaluation of adiabatic properties, and its predicting model was proposed with CFD. In addition, we also attempted to evaluate true thermal conductivity in consideration of lateral heat dissipation during measurement by thickness. As a result, we found out the influence of the fiber diameter and thickness of the nonwoven fabric on the thermal conductivity, and demonstrated that the proposed CFD model was effective to estimate the characteristic of the thermal conductivity of the nonwoven fabric.

Ozone has a strong oxidation capability. It is often used for water treatment system. However, ozone has the demerit that it is difficult to be dissolved in water. Therefore, we used micro- bubble in order to dissolve ozone in water. The diameters of the micro- bubbles are less than 50μm. The micro- bubble has features that are slow ascent rate and high inner pressure. In this study, we conducted a water treatment using the micro- bubble ozone in order to improve the efficiency of the ozone treatment. The experiment shows dissolved ozone and BOD increased by the micro- bubble ozone.

This research proposes a volute pump with a simple structure in which circular tubes are radially combined, and verified a pump performance and characteristics by numerical analysis and experiment. As a result, it was found that when the Coriolis force becomes dominant in the pipeline, the gas phase entered from the discharge port, and the performance of the pump decreases.

In this paper, we present and validate a shape optimization framework for the design of splitter blades that extends the operative range under cavitation while maintaining the wetted performance of centrifugal pumps for industry. The paper breaks new ground in defining an efficient design methodology for the improvement of efficiency and cavitating performance in turbo pumps.

In recent years, gas turbine combined cycle has become a main current of the thermal power generation in Japan. Therefore, to achieve further high efficiency of high-loaded turbine in order to effectively utilize energy resources is very importance. In this research, the loss generating mechanism in gas turbine cascade is revealed by automatic measuring system of cascade performance, visualization test rig and CFD analysis, the secondary flow loss reduction was investigated analytically and experimentally, In addition improvement of the loss reduction effect was examined by applying optimization method using CFD analysis

Diffusers are extensively used in many industrial aspects. So, diffusers with high efficiency are desired under both spatial and cost's limitations. In our previous studies, we proposed a flow deflector inside the diffuser-part of an automotive catalytic converter, in order to reduce energy loss and to improve thermal uniformity. In this study, we experimentally and numerically investigate the influence of the downstream substrate upon the effectiveness. As a result, it is revealed that the flow deflector is effective for diffusers as well as catalytic converters. By computation, we have shown the flow inside the diffuser with the flow deflector.

We have conducted laboratory experiments to determine the critical parameter (Poincaré number) for unsteady flow to be sustained in a precessing sphere and spheroids with small ellipticity. We show that the critical Poincaré number significantly depends on the cavity shape and the spheroids require much stronger precession than the sphere. We also derive the scalings of the Reynolds-number dependence of the critical Poincaré number, which perfectly explain our experimental results.

The purpose of this study is to develop a high-performance micro-gas turbine. For this purpose, we analyzed the gas flow inside a compressor and a turbine by using computational fluid dynamics (CFD). We optimized the angle of the impeller blades of the compressor. As a result, the total pressure ratio of the compressor has been improved by 30% in comparison to previous model. Then, the power of the turbine was improved for 21.6[W]. Moreover, we analyzed both systems with changing revolution number (changed to 500,000rpm from 900,000 rpm) to enhance the possibility of this systems.

To understand the generation mechanism of small-scale vortices in a high-Reynolds-number turbulent boundary layer, we identify coherent structures by applying a Gaussian filter to the velocity. By evaluating the contribution of the coarse-grained strain to the stretching of coarse-grained vortices, we show that small-scale vortices are generated predominantly by twice larger vortices rather than by the mean flow stretching, which is consistent with the picture of the energy cascade. In contrast, small-scale vortices are directly stretched by the mean flow at low Reynolds numbers. The disappearance of hairpin vortices as the Reynolds number increases is therefore explained by the difference of these two mechanisms.

A precessing container is useful for turbulent mixing of the confined fluid. Fully developed turbulence is sustained by a weak precession. We examine the turbulence suppression in the container by a small amount of surfactant additive by means of flow visualization and particle image velocimetry to reveal the sustaining mechanism of the developed turbulence of water, a Newtonian fluid. Considering our experimental results with previous theories about the onset of the turbulence suppression, we conclude that developed turbulence in a precessing container is sustained by an energy cascade.

Particle image velocimetry (PIV) measurements of streamwise-spanwise (x-z) planes over isotropic and anisotropic porous media are carried out to understand the turbulence characteristics. We consider six kinds of porous walled channel consisting of isotropic and anisotropic porous media. Three isotropic porous media are foamed ceramics, and the others are handmade anisotropically layered meshes. By the two-point correlation analysis, it is confirmed there is a periodic turbulence structure over porous media induced by the Kelvin-Helmholtz instability. It is found that its streamwise lengthscale normalize by the friction velocity on the porous wall has a linear relationship with the shear Reynolds number.

Understanding turbulent flow physics near a porous layer is important for designing industrial devices. However, anisotropic effects of the permeability on turbulence near porous interfaces are still unknown. Thus, this study tries to perform 2DPIV measurements not only over but also under the interfaces of porous media constructed anisotropically with transparent acrylic square rods. In the region under the porous interface it is found that the streamwise permeability has far more significant influences on turbulence generation than the wall-normal permeability.

We propose that the Stokes-number dependence of inertial-particle clustering in turbulence is explained in terms of the structures extracted from the coarse-grained fluid acceleration, and investigate the spatial correlation between the structures and the clusters of particles. To verify this proposal, we conduct direct numerical simulations of the inertial particles subjected to the linear Stokes drag and suspended in homogeneous isotropic turbulence.

In recent years, flow cytometers are used in the field of research. In order to detect cells, it is necessary to align the cells in a line. Currently used methods are those by wrapping the sample solution with sheath flows. In this method, problems such as an increase in size of the apparatus due to complication of the structure are pointed out. Therefore, we proposed a focusing method that consists of multiple parallel flow channels in the flow channel without using the sheath flow by performing numerical analysis, and confirmed the focusing of the fine particles by conducting experiment.

The growth and collapse of a bubble between two free surfaces are simulated by using the boundary element method for understanding the bubble dynamics in a plane free mercury jet. The influence of pressure gradient in the liquid on the deformation of the bubble and free surfaces are investigated. After the bubble takes the maximum volume, the pressure gradient arises between nearer free surface and the bubble interface leading to the liquid jet formation for the bubble interface and the rapid growth of the water column on the free surface.

Particle clustering phenomenon is relevant to many industrial and natural systems. Particles denser than the carrier fluid tend to accumulate in the high-strain low-vorticity regions, which leads to inhomogeneous distribution of particles. This phenomenon is known as “preferential concentration”. The deposition and entrainment of particles in low-Reynolds number turbulent channel flow is well understood. However, particles clustering under the influence of multi-scale vortices in high-Reynolds-number turbulent channel flow is not fully investigated. Present study aims to understand this situation through the DNS of particle-laden turbulent channel flow at Re_τ = 500 and 1000.

Hydro fluoro olefin (HFO) and hydro carbon (HC) refrigerants have been considered for use in air-conditioning systems and refrigerators as low global warming potential (GWP) refrigerants. These refrigerants are determined the lubrication performance of the sliding parts in compressor. To clarify lubrication performance of unsaturated and saturated refrigerants for these low GWP refrigerants, seizure and wear tests were done in the compound of liquid refrigerant and refrigeration oil. Immiscible oils to refrigerants were used for lubrication. We confirmed that antiwear and antiseizure characteristics of unsaturated refrigerants (HFO-1234yf and R1270) are better than those of saturated refrigerants HFC-134a and R290.

The significant properties of sintered Tungsten Carbides such as high hardness and high heat resistance, enables itself to apply widely to molds and dies. The research on establishing a cutting technology of the sintered Tungsten Carbide have been pursued especially for the last decade in turning. We have been focusing on building an efficient cutting method of the sintered Tungsten Carbide with diamond coated tools, and investigated their respective wear properties. In this paper, we examine the capability of diamond coated ball end tools in milling of the sintered Tungsten Carbide.

We developed several equations and finite element analysis method for estimating bolt tension under repeated tightening by hydraulic tensioner. The axial tension remaining in the bolt is less than the initial tension by the hydraulic load. The axial tension varies under repeated tightening because of settling and work hardening on bearing surface. As a result of this study, we clarified that the axial tension in 2^nd joint is higher than that in 1st joint due to decreasing of settling and plastic deformation. Further, we confirmed that the analysis method could estimate the axial tension accurately.

It is reported that it shows an extremely small coefficient of friction by using graphene as an additive of the lubricating oil or a friction material. In this study, I paid my attention to graphene and CNT (carbon nanotube), and I formed graphene and CNT using Surface decomposition method. I inspecting the friction characteristic of these materials after I examined the friction

Polyethylene glycol (PEG) is expected as a biodegradable oil for stern tubes. In this study, its tribochemichal reaction with calcium lactate additives was examined. It was found that the friction coefficient PEG oil with calcium lactate additives was a little bit of lower than only PEG oil. Surface and lubricant oil were analyzed by Raman spectroscopy and XPS. Analysis results revealed that the iron oxide on plate surface decreased and that in the lubricant oil increased by calcium lactate additives.

Hydrogen for fuel-cell power plants is commonly manufactured from hydrogen-rich materials such as hydrocarbons and alcohols, using steam-reforming with catalysts. Recently, the authors have investigated the optimum conditions for efficient and endurable steam reforming. In the present study, the authors investigate the optimum conditions, especially focusing on both the influences of LHSV upon concentrations and the ethanol conversion. As a result, all the concentrations are close to the theory except for the case at low T_R and high LHSV. To settle the inconsistency of this exceptional case, the authors propose a new theory using some chemical reactions related with acetaldehyde.

Urea SCR system is effective post treatment device of diesel engine to remove NOx in exhaust gas. The purpose of this study is constructing simulation model capable of predicting spray behavior and NH₃ concentration distribution.

Post injection has been attracted attention as Diesel Particulate filter regeneration method. However oil dilution that occurs when fuel spray impinges lubricating oil film on cylinder liner is an issue which cannot be ignored. Because oil dilution is leading to deterioration of thermal efficiency, there is need to clarify spray impingement behavior on lubricating oil film. Therefore, in this research, we focus on oil dilution phenomenon by post injection and aim for modeling. Then, the critical weber number was measured to make it possible to judge whether or not the fuel droplet impinges on lubricating oil film splash or deposition.

It is possible to improve the efficiency by applying marine engine technology to passenger car engine. For that, similar applying of the combustion process of marine engine is effective.

Shadowgraph images of the diesel spray developed under high-density atmosphere were taken using a Rapid Compression/Expansion Machine and characteristics of spray shape were analyzed. From the experimental results under various conditions, it was shown that the penetration increases as the ambient pressure is lower and the injection pressure is higher, that the divergence angle of the spray strongly depends on the atmospheric pressure and does not change so much with the injection pressure. Also, the change of spray characteristics with the restriction of flow path width was discussed.

We propose the use of a removable prechamber in a gasoline engine as an amplifier for the spark plug to cause lean ignition in the main combustion chamber, and we explore the possibility of charging the prechamber with a slightly rich mixture without additional fuel delivery. For these purposes, we model a prechamber compatible with any engine without additional scavenging systems. In addition, the inlet velocity of a centrally located self-scavenging prechamber is investigated numerically.

Effect of the air-fuel mixture characteristics in the vicinity of ignition plug on flame propagation is investigated based on the flow measurement result and combustion analysis for a spark ignition combustion process. Particle image velocimetry (PIV) method is performed to measure the in-cylinder fluid motion of a rapid compression expansion machine (RCEM). The results show that the local velocity fluctuation around ignition plug significantly affects the initial combustion rate.

The objective of this study is to find the strategies for increasing thermal efficiency of light-duty diesel engine by means of managing both cooling loss reduction and increase in degree of constant volume. For this purpose, a combustion strategy combining premixed charge compression ignition (PCCI) based combustion and conventional diesel combustion is examined. Experiments were performed using a single-cylinder light-duty diesel engine with two common-rail injection systems which enables independent control of fuel injections for PCCI and diesel combustion. This report focuses on investigating basic characteristics of the performance and exhaust emissions.

This study proposes the modeling scheme of easily and precisely prediction of engine characteristics by combining the statistical methods with physical theories. In this report, the effect of DoE, such as D-optional design and LHS (Latin Hypercube Sampling), on the modeling accuracy is examined. Furthermore, it was investigated whether Two-zone model can reduce experimental points which need constructing this model.

This study aims to obtain a strategy for optimizing the combination of diesel-fuel injection conditions and combustion chamber geometry to achieve high thermal efficiency with low exhaust emissions in a natural-gas/diesel dual fuel engine. Experiments were performed using a single-cylinder test engine with a common-rail injection system varying injection timings of two-stage pilot injection and piston bowl diameter. The pilot spray development was calculated using CFD simulation to understand the mechanism of experimental results. The experimental results showed that a smaller bowl diameter reduces THC and NOx emissions under a condition of high equivalence ratio, and the CFD results showed that the smaller bowl diameter provides a richer mixture of 1^st pilot injection and a leaner mixture of 2^nd pilot injection than a larger bowl diameter.

To develop the combustion method with combination of PCCI and conventional diesel combustion, mixture formation process of early injection was investigated using an optically accessible single-cylinder diesel engine. Effects of injection pressure, injection timing, injection quantity, split injection, and the dwell between injections on spray penetration and mixture distribution were investigated. The penetration was measured by a high-speed photographic method, and the mixture distribution at TDC was observed by the LIF imaging method. When applying high injection pressure and split injection, relatively rich mixture spreads across wide area in the combustion chamber.

This study researched effect of fuel heating on gasoline spray and combustion characteristics.

Ignition and combustion in the natural-gas DDF operation at various mixture conditions and injection quantities of diesel fuel were fundamentally investigated using a rapid compression/expansion machine. From the experimental results, requirements of intake pressure and oxygen fraction at different natural-gas equivalence ratios for ensuring the stable ignition and the high combustion efficiency were discussed at a constant intake-pressure condition and a stoichiometric condition.