Mechanical engineering frequently uses continuum mechanics. It is rare in academic sciences. There are cases that continuum mechanics is needed to make some materials, e.g., for light emitting diode, in applied physics, especially, mass production. However, this mechanics is not sufficiently learned in applied physics. The theories in mechanical engineering are effective in such cases. We have to report results carefully to understand them in applied physics because the common knowledge in mechanical engineering is not common knowledge in sciences. This presentation deals with solid solution growth from liquid solution. There are fluid flows in the liquid solution. In the traditional calculations, the results are buried under errors. This presentation deals with a case without these flows to prepare to deal with these flows. The liquid solution is supersaturated just before growth. The temperature is constant during the growth. This presentation shows an analytic solution. This analytic solution derives that the composition of solid solution is constant. It becomes a baseline in numerical simulations.

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Several kinds of commercial and mechanical flowmeters, namely, turbine meters and positive displacement flowmeters, have been calibrated using the primary standard for hydrocarbon flow measurement in Japan, which is based on static and gravimetric methods with a flying start and finish, and a small volume prover (SVP) at the same calibration condition in order to investigate the performance of the SVP. The calibration results for the mechanical flowmeters between the primary standard and the SVP show agreement within 0.05%. However, the relative differences of the K factors using the SVP from those using the primary standard are dependent on the flow rates, indicating that the SVP should be calibrated in the all flow rate range instead of a constant displacement of volume in order to achieve a lower uncertainty.

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Although the sirocco fan has the characteristics of high pressure and high quantity flow, there is a problem with the noise which easily becomes loud. The purpose of this study is to clarify the effect of the number of blades on the flow field of the sirocco fan at the maximum efficiency point, using numerical analysis (large eddy simulation). In addition, two sirocco fans with a small number of blades (N=22, 11) were used for this study. As a result of the numerical analysis, there was no significant difference in the characteristics of the velocity vector between the blades at Z/W=0.95 at maximum efficiency point. For Z/W=0.40, it was shown that the area of flow separation is increased and the characteristics of the velocity vector between the blades is greatly different in the case of N=11 as compared with N=22, because the area between the blades is larger.

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In this paper, we propose two-step collector as a pulsation suppression method on open jet circular wind tunnels. The experimental results show that two-step collector decreases the peak power spectrum of velocity fluctuation by 70% and that it is an effective method for pulsation suppression. On the other hand two-step collector decreases the static pressure in the downstream side of the test section, i.e. it forms a different static pressure distribution from usual collector.

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Aerodynamic characteristics have great influences on vehicle performance. The aim of this research is to analyze the influence of configurations of road vehicles on aerodynamic characteristics. As configuration parameters, not only the rear window angle but also the side-window angle are adopted, and totally 55 patterns of configurations changing from box type through fastback to notchback types are investigated by wind-tunnel experiments. As results, in the cases of side angles less than 30°, the drag increases steeply at rear angle from 20° to 35°, while in the case of side angle 30° this tendency was not detected. It was shown that as the side window is slanted, increase of drag occurs gradually at larger rear angle, and the drag increment becomes smaller. In the whole cases the larger the side angle is, the less the drag is. The factor is that as the inclination of the side window is larger, the angle between the rear and side surfaces becomes more obtuse, and the formation of longitudinal vortices is restrained. The flow visualization confirmed the factor.

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Recently, reduction of CO_2 emission from automotive is required. In order to reduce CO_2 emission from heavy duty vehicle such as truck and trailer, its drug force in aerodynamics need be improved. In this study, drug force of 1/32-scale truck model attached a wind deflector (various front and rear angles) on its truck container was measured using small-scale wind tunnel. Moreover, the drag force, flow patterns and pressure distributions were calculated by a Computational Fluid Dynamics. As the result, it was confirmed that the drag force could be reduced by wind deflector an attached on the container. That is because it was reduced a size of wake flow and be increased a static pressure behind the truck model.

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To investigate the effects of Coriolis force on turbulent boundary layer developing on top, bottom and side walls of a rotating, rectangular channel of low aspect ratio, quantitative experiments were performed. Time-mean velocity and turbulence intensity were measured in detail by a hot-wire anemometry. From the experimental results, the boundary layer development was found to be promoted strongly on the low-pressure (trailing) side and suppressed on the high-pressure (leading) side, in comparison with the case of zero-rotation due to the secondary flow effect of Coriolis force. Secondary flow near the surfaces of top and bottom walls of the channel inhales fluid of high turbulence energy and low momentum from the high-pressure side, and stuffs it into the boundary layer on the low-pressure side. Also, flow in boundary layer was stabilized on the low-pressure side and destabilized on the high-pressure side due to the stabilizing and destabilizing effects of Coriolis force, respectively.

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Numerical simulations were conducted by using LES (Large Eddy Simulation) with DSM (Dynamic Smagorinsky Model) about the axial flow small fan for cooling electronic devices. In this study, the tested fan has grid for turbulence located in the suction side. Using two type of grid for turbulence were used for study. One has diameter of 3mm and pitch of 15mm, the other has diameter of 4mm and pitch of 20mm. The flow pattern around the fan blade and RMS of pressure fluctuation on the fan blade surfaces were compared under the two turbulence conditions and no turbulence condition. As a result, it is shown that noise is increased by the grid for turbulence. These cause are considered large pressure fluctuations which were revealed by numerical analysis. In addition, we found that increase in RMS of pressure fluctuation is related to incidence angle fluctuation. This phenomenon is likely to occur at leading edge. And this area is influenced by inflow turbulence.

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The mixing flow of supercritical water and liquid water in a T-shaped channel is simulated using the Cartesian mesh method coupled with a least-square meshless method. In the present method, the Supercritical-fluids Simulator (SFS) is coupled with the Building-Cube Method (BCM), because of its simplicity and efficiency; and a meshless method is further applied to the wall boundary treatment because of its flexibility. Two test cases are conducted: First, a simple experimental validation is proposed to show the effectiveness of the present method; then, the numerical validation is also proposed, and the numerical results by the immersed boundary method are used for comparison, the advantage of the meshless method over the immersed boundary method is clearly shown. The present method is proved to be a promising tool for 2-D practical supercritical-fluid flow simulations.

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Supercritical-fluids simulator (SFS) developed by our group is coupled with a particle formation model of the rapid expansion of supercritical solution (RESS) process. In SFS, a numerical method based on the preconditioning method and PROPATH is used for evaluating accurate thermophysical properties. In this paper, the particle formation of Naphthalene in the supersonic flow is calculated considering condensation of CO_2. The results indicates that the region of particle formation is different from the region of CO_2 condensation.

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Study of detonation engine has been actively carried out in order to improve the thrust performance and expected to apply rocket engine. Even among them, rotating detonation engine has attracted attention. Many experiments have been performed, but in the experiments, varying the combustion chamber size is difficult. In this study, the numerical study is carried out to find out thrust performance with changing combustion chamber size.

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Three-dimensional numerical analysis using practical scale of the experiment is performed to obtain cellular structure in rectangular tube. As a result, transverse wave in three-dimensions moves in different direction comparing with two-dimensional structure at the point of propagation structure. Furthermore, each transverse wave affects to accelerate the propagation velocity in circumferential direction and makes unreacted gas pockets after transverse wave goes through each other.

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At the reflected shock rear, a chemical reaction starts at a temperature and pressure constant static premixed gas conditions by filling reactive premixed gas in the shock tube, and reflects the shock wave in the pipe ends. Meyer and Oppenheim were classified into ignition two forms Mild Ignition and Strong Ignition, the start of the H2/O2 detonation due to the reflected shock wave. In order to ignite instantly in the tube cross-section of the entire near-wall reflection, Strong Ignition is a form ignition reaction theory. Mild Ignition is a firing mode hydrodynamic, under the influence of lambda shock wave generated by the mutual interference between the boundary layer and are reaching the ignition shock wave backward flow becomes multidimensional. Mark was revealed from the experiment due to the mutual interference between the boundary layer and the reflected shock, lambda shock wave to be formed in connection with this phenomenon. Thus, experiments by the reflected shock ignition is performed, there are cases in which ignition occurs is unexpected due to the interference of the reflected shock wave and boundary layer. In this study, we focus on the flow field due to the interference of the boundary layer and reflected shock, it is an object of the present invention to elucidate the flow three-dimensional.

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One of self-ignition mechanisms of high-pressure hydrogen jet occurs by vortex caused from instability. Several studies about self-ignition of high-pressure hydrogen spouted from a tube attached with a tank are reported. In this analysis, the numerical study is performed to find out mechanism of self-ignition of hydrogen jet in a tube with a 10mm in diameter connected to a high pressure tank of 9.0MPa. Hydrogen and air are mixed at their contact surface to yield vortices, and the mixture ignites because the high temperature and high pressure regions are yielded behind the precursor shock wave.

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Cold spray can make a coating on a wide variety of mechanical parts by spraying solid particles accelerated by a high-speed gas flow through a converging-diverging nozzle. Experimentally it is well known that the particles start to deposit on the substrate when the impact velocity exceeds material-dependent threshold value. Therefore, the particle velocity at impact is important in the cold spray. Particle velocity is dependent on various parameters. One of parameters is the total gas temperature. The particle velocity is dependent on the total gas temperature, however, it decreases due to heat transfer from the gas to the spray particles injected in the nozzle. In this study, the decrease in the total gas temperature due to heat transfer from the gas to the spray particles is estimated using a simple model for two different spray materials. The analysis was performed using helium and nitrogen as working gas.

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Feedforward control to suppress the instability waves whose frequency changed periodically is attempted in a wind tunnel experiment of a fla plate boundary layer. It is shown that the control effect can be improved by taking into account the dispersibility of the target instability waves.

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Vortex tube (VT) is a simple mechanical device which separates cold and hot streams from room-temperature compressed gas. Generally, the VT can produce cold stream down to around -30℃ and hot stream up to around 130℃. The flow properties inside and outside of the vortex tube are important in order to elucidate the temperature separation phenomenon, which is not fully understood. In this research, Pitot pressure probe is used to measure the pressure of the cold exit. Pitot pressure probe was inserted along the central axis of the cold exit. The pressure is measured in the range of 0-15mm from the cold exit. The results shows the Pitot pressure is negative at the cold exit at a cold fraction ε< 0.53, and inlet pressure at 0.2 and 0.3MPa.

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This paper describes the experimental study of the characteristics of a non-contact type suction device using Coanda effect. The present study has been carried out for flow analysis around a non-contact suction device. The main aim was to obtain the useful data for CFD analysis by suitable visualization. TiO_2 and glass bubble particle shows the difference of the flow pattern around the non-contact suction device with work and without work well. It is found that the range of the flow velocity is too wide to fix the suitable photography condition. A high speed video camera is applied to show flow pattern. The flow direction changes too drastic to be traced by glass bubbles.

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To mitigate the CO_2 concentration, methods exist for the air-cooling using the evaporative latent heat of water for conservation of electric power. In this report, the temperature for cooling using the latent heat of water from a paste-moisturized test cloth on plates in duct was investigated. The enthalpy for air cooling was measured in the velocity range from 0.5 to 3 m/s and the relative humidity range from 20 to 65 %RH. As the result, the temperature of air decreases with increasing the velocity and relative humidity, and the enthalpy is unchanged.

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We measured the discharge coefficient of critical nozzles using hydrogen gas in high Reynolds number (Re = 2.5 x 10^5 - 1.6 x 10^6). It was confirmed to deviate from the universal curve prescribed in IS09300, and to indicate high value of the critical back pressure ratio. In high Reynolds number, it was not necessary to take large differential pressure in the use of critical nozzle.

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The interaction phenomena between the shock wave and the plasma was experimentally investigated. Due to the interaction, the shock wave deformation and attenuation were observed. And, the result suggested that the shock wave modulation effects became more significant with increasing shock Mach number. This tendency was also observed in one-dimensional theoretical prediction.

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An radial underexpanded jet is generated in high pressure flow field such as an intake flow through a poppet valve of reciprocating engine, a flow through a main valve of pressure reducing valve and wall jet formed by an impingement of supersonic jet on an object. The radial underexpanded jet resembles an axial underexpanded jet in some ways. Like the axial jet, a cell structure is seen in the radial jet and is visualized as 'shock ring' through which the radial jet flows and spreads. As the radial jet goes downstream, the distance between neighboring shock rings becomes shorter with decrease in thickness of the jet because a cross-sectional area of jet is kept constant. In this study, the structure of the radial free jet without a wall is experimentally analyzed by measuring the sound pressure emitted from the jet and visualizing the flow field from two directions. As a result, a screech tone is measured at high frequency and the frequency decreases as the supply pressure of jet increases. The Strouhal number in two dimensional jet agrees well with Strouhal number estimated using a thickness of 1st or 2nd cell node in the radial jet.

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In petroleum plants flammable gas is massively produced as a by-product in refining gasline, diesel oil and etc. Such unnecessary gas in high pressure is released by a regulation valve into a pipe connected to a flare system. Under a certain condition, the pipe violently vibrates with loud noise which leads to the fatigue of the pipe system in a short time. The vibration of the pipe is caused by acoustic energy radiated from the valve and resonates with the gas in the pipe, which is referred to as Acoustic Induced Vibration. In the present study, a pipe is experimentally vibrated by sound wave emitted with different frequencies and the strain of pipe is measured in order to elucidate the mechanism of destruction of pipe. As a result, it is shown that the resonance between fluid in a pipe and the pipe wall may occur with the same natural frequency and the same wave number.

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This paper focuses on a sensor, which provides information of shock propagating in flow field such as its strength and direction. The diaphragm of sensitive head of pressure transducer, on which a semi-conductor type strain gauge is glued, is analyzed using FEM and the relation is discussed between behavior of the diaphragm over which the shock passes and the direction in which the shock propagates. The numerical analysis offers the strain distribution of surface of the diaphragm depends on the shock direction and the direction of maximum principal strain of the diaphragm conesponds to the direction in which the shock propagates or its perpendicular direction. Experimentally, strains of the diaphragm in different directions are obtained and the direction of maximum principal strain is estimated using Rosette analysis, being compared with the shock direction. As a result, the shock direction was found to be estimated to some degree of accuracy due to the Rosette analysis using a scheme proposed in the present paper.

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In this paper interaction process between shock wave and solid is discussed. Such phenomenon is known to be one of the reasons of serious problem, such as the destruction of glass and structures by shock generated from supersonic plane, explosion and so on. In recent years, although the mechanism of interaction has been studied by many researchers, the details of process have not been known enough yet. In this study, the interaction phenomenon between a shock wave emitted from a diaphragmless shock tube and a solid block having different shape made of polycarbonate is experimentally visualized using Schlieren method. Strength of the impact force generated by shock impingement is evaluated by numerical simulation of the flow field using TVD scheme. As a result, stress wave is formed by the shock collision and propagates in the block and it is found that the shape and the propagation speed of stress wave depend on the shape and the material properties of block.

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As a part of study on the diffusion control of jet flow, the purpose of this study is to control the jet diffusion by using the deforming nozzle. The shape of polypropylene nozzle can change from square shape into cruciform one smoothly. The velocity measurement of the jet flow was performed using a hot-wire anemometer, by changing the shape of nozzle variously. The basic characteristics of the jet flow, such as velocity distributions and half value widths have been obtained. As a result, it has been clarified that the jet width in xOy'-plane is large, comparing with that in xOz-plane. Moreover it has been also found that the effect of deforming of the nozzle on jet diffusion is appeared in xOy'-plane.

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We measured the steady contact thermal resistance between two aluminum plates by changing parameters: surface roughness, contact pressure, fluid in the space, and distance of the space. We found that effective ways to change the contact thermal resistance are to change distance of the space and to change fluid in the space. Then we experimented on the dynamic change of contact thermal resistance by changing distance of the space using vacuum or non-vacuum conditions in the space. The results show that the contact thermal resistance can be changed every 5 s with the changing rate of 30%.

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In this study, two-dimensional thermal cloak for circular domain is discussed numerically by using transformed steady heat conduction equation and finite-element analysis. It was found that both of ideal cloak and Han's cloak work well for cloaking a circular domain within a rectangular conductive domain having two thermal boundary conditions.

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The final object of this study is to enhance the heat-exchange performance of fin-plate heat exchangers using ionic-wind generated at the surfaces of each fin. In this study, an ionic-wind generator consists of a glass plate, a discharge electrode and ground electrodes put on the glass plate. Ionic wind is generated by applying AC high voltage of 13.5 kHz with DC bias. When the peak and the DC bias voltages were 6 kV and 2.25 kV, respectively, the maximum wind velocity was 1.3 m/s at within 1.0 mm from the surfaces. The ionic wind generated vortices, resulting in a little wind of the reverse direction at the position of y-coordinate larger than 1.5 mm.

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Nucleate boiling enhancement technique with "re-entrant cavities" has already been well known. However, there are restrictions on the material and shape of the heat transfer surface, and it has not been popular yet. The purpose of this study is to form re-entrant cavities on the heat transfer surface by welding aluminum foil with a fine structure and to develop the nucleate boiling enhancement surface applied to a wide range of fields. Boiling heat transfer coefficients of the developed enhancement surface were measured and compared with those of smooth one. Test refrigerant is HCFC 123 and the test pressure is 1 atm. The enhancement rate of about 10 was obtained.

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In recent years, with the technological advance of electronic device, increasing of heat emission and decreasing of surface area by downsizing have been challenging problems. Therefore, thermal efficiency and safety are more important than ever. We had applied high-carbon alcohol aqueous solution to boiling with impinging flow in mini channel to promote the boiling heat transfer. With three thermocouples which were inserted near the heat transfer surface, we calculated the heat flux and the temperature of the heat transfer surface by the temperature gradient obtained from them. The high-carbon alcohol aqueous solution realized higher dryout heat flux than others. In addition, the maximum value of CHF was found to be dependent on the concentration of the solutions. We investigated the flow velocity on the bubble and liquid interface with the numerical model which analyzed the Marangoni convection mechanism. In this model, butanol aqueous solution also indicated that the maximum value of the flow velocity existed for some concentration of the solutions. This suggested the relationship between the experiment and the numerical model in terms of maximum CHF.

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Silicon plate of thickness 100μm has a characteristic of flexible bending, and thus, new added value can be provided. In this study, we investigated a new horizontal pulling method using surface tension because the production less than 100μm were difficult by conventional methods. We draw solidified thin plate from a slit of the crucible. This experiment is a model experiment using the metal with low melting temperature. As a result, we succeeded in obtaining stable thickness of 200mm. In this experiment, the slit width (=metal plate width) was 20mm. In this study, we investigated how the slit width change will affect the melt temperature at the slit, which is the most important parameter in the process.

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A ground source heat pump (GSHP) is paying attention as one of the energy saving technologies. The purpose of this study is to investigate the heat exchanging performance of the ground source heat pump system using direct expansion method. The direct expansion method is efficient compared to the indirect heat exchange method which is known as conventional technique. The GSHP system using direct expansion method circulates the refrigerant to underground directly. The calorimetric measurement in primary side of GSHP system using direct expansion method is difficult because the refrigerant which circulates to underground is two phase flow. Therefore, the performance of GSHP system is evaluated in secondary side by measuring the enthalpy difference. The accuracy of measurement is also evaluated in this study.

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This promising model for this rapid heating-cooling device is a two ways heat pump that can generate heat and cool down by adsorption and desorption processes of desiccant. First two desiccants that are a conventional one treated with silica gel and another one is zeolite 13X were tested. By comparing basic characteristics of these desiccants such as humidity adsorption capacity, specific surface area, pore size and particle size was clarified that zeolite 13X has better performance in order to adsorb water vapor than silica gel. So, the zeolite 13X has been chosen for test material in this research. Then, a test device that contains the zeolite 13x was fabricated, and the performance of heat generation and cooling was experimentally examined. The results showed that this device can raise surrounding solid wall's temperature up to 40 K higher by adsorption of humidity and the maximum rate of heat generation is 4.8 W/g. It is also be able to cool down surrounding solid wall's temperature 15 K lower by desorption of water from the desiccant. Using the obtained results, a model that can estimate the heat generation/cooling process in the device was derived, and the optimum operation condition was discussed for injection molding application.

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An experimental study has been conducted to obtain thermal characteristics of the rotational type magnetic heat pump with two different layouts of magnetocaloric materials. These layouts are arranged with two different materials. Gd and Gd_<0.89>Dy_<0.11> which show large temperature change comparatively through low temperature range around 15 degree Celsius is applied and arranged in the center and the left side of the cell inside the rotor. The left side arranged layout showed maximum COP of 1.7 and showed larger than center arranged layout in most of the conditions. Center arranged layout showed maximum temperature difference of 3.4 degree Celsius, but its COP was smaller than left side arranged layout in most of the temperature range and flow rate range.

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The aim of this study is to develop the Object-oriented method for deducing temperature on apparatus, understanding how to relate flow with heat transfer characteristics of coaxial cylinders which simulates an Electric Vehicle (EV) motor geometry. There are two experimental apparatuses, for flow visualization and for temperature measurement. In addition, numerical simulation of flow and heat transfer inside model of an EV motor is achieved. Heat transfer on gap and rotor-end part are good agreement with experimental result of which Nu=0.21(TaPr)^<1/4> and Nu=1.26Re^<0.385>, respectively. Moreover, thermal network model in the experimental apparatus is achieved in order to estimate heat transfer characteristics among every part. It is shown that under the detailed physical perspective, complex thermal relation can be reduced into linear relation among elements.

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In order to solve EV issues, AI-EV (Air-conditioner Integrated Electric Vehicle) which is integrated with power souce for running an air-conditioner and a vehicle has been proposed. In this paper, the authors have studied the method that is improved the efficiency of air-conditioner and evaluated the performance of AI-EV. As a result, according to improving heat transfer area of a condenser and recuperating an engine exhaust heat, COP (coefficient of performance) is able to increase 1.4 times. Therefore, the cruising range of an AI-EV which is mounted the advanced air-conditioner is able to be extended more than 1.1 times in comparison with a conventional AI-EV.

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Heat recovery from flue gas is very effective in order to economize fossil fuel consumption, and results in the reduction of CO_2 emission. However, the temperature of flue gas decreased with increasing the amount of recovery heat. It seems that the decrease of temperature causes formation of secondary condensed particles in a flue gas, and these particles is probably serious problem for air pollution and human health effect. In addition, the use of vegetable oil has an advantage as an alternative to fossil fuels for reduction of CO_2 emission. In this study, kerosene and kerosene with vegetable oil was burned using a spray combustion furnace and the flue gas was cooled by a heat exchanger. Flue gas was sampled from the stack, and PM size distribution and PM composition in the gas were analyzed. As the result, the mass of PM decreased by addition of vegetable oil. However, particles which were speculated as secondary condensed particles increased.

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In this study, PM aggregation technology in high humidity field was attempted by means of water-mist addition. PM exhausting from a laminar diffusion flame formed on a small pool of benzene (C_6H_6) was used for test sample. Water mist of which peak diameter was around 10 micro-meters was co-flowed and mixed with burned gas stream containing PM. Size distribution, mass of PM and water content in PM were measured by a Scanning Mobility Particle Sizer (SMPS3936, TSI Inc.), a Low Pressure Impactor (LP-20, Tokyo Dylec Corp.) and filter method. As for the PM from benzene flame, PM diameter corresponding to a peak number concentration existed within a range of 200nm - 300nm and its number was around 4x10^7 #/cm^3. Number of PM after mixing with water-mist decreased to around 1x1O^6 #/cm^3, however its diameter range shifted from nano-meter range to micro-meter range over 5 micro-meters. This diameter shift was confirmed by the LP-20 that had wide measurable range of particle diameter. Moreover, PM captured on glass-fiber filter showed that moisture in water-mist-treated PM was extremely higher than non-treated PM. From this result, it was considered that PM aggregation with water-mist was the main reason of peak diameter shift mentioned above.

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Nanometer size particulate matter (PM) has harmful effects on human health. PM characteristics such as size and compositions were required to develop reduction technologies for reduction of combustion origin PM. In this study, characteristics of PM emission from quenched flame of benzene fuel were measured by a combustion type PM analyzer (MEXA-1370PM). In addition, oxidation temperature of PM and its density were also measured by a TGA (Thermo Gravimetric Analyzer) and a Hydrometer. From these results, it was confirmed that PM emitted from quenched flame included SOF with high mass concentration.

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Since the engine combustion is affected by various engine parameters as well as fuel characteristics, it is very difficult to find out the clear effect of fuel property on it. In order to clarify the change of emission characteristic caused by fuel trend, we propose a fundamental flame research method using a small pool flame system. Exhaust rate of PM emitted from laminar diffusion flames of gasoline fuels (JIS No.1 and No.2) were investigated by filter sampling method. From this result, it was cleared that gasoline flames, PM exhaust rate of JIS No.1 gasoline flame was higher than that of JIS No.2 gasoline. Then, hydrocarbon fuels of various chemical structures such as alkane, alkene, iso-alkane, iso-alkene, cyclo-alkane, cyclo-alkene and aromatic were also investigated. From these results, relation between chemical structure and PM exhaust rate was discussed.

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Ignition properties of laser-induced breakdown sparks and electrical spark ignition were examined experimentally to choose an ignition method to investigate ignition limit of volatile components from heated materials in a microgravity experiment. Firstly, the characteristics of each ignition method were investigated for methane/air mixtures. In the case of electrical spark ignition, the minimum ignition energy depended on the electrode gap. On the other hand, in the case of laser-induced breakdown sparks, the minimum ignition energy did not depend on the focal length. Effects of gravity were clearly observed for lean mixtures in schlieren images of flame kernel development. Components of PMMA pyrolysis gas were examined using a gas chromatograph. Ignition behaviors of MMA/air mixtures, which are supposed to be produced from PMMA, were investigated. The minimum ignition energy for mixtures with various equivalence ratios was measured to identify the ignition limits of the gas. A change in ignition energy with an increase in the equivalence ratio was observed. Fundamental data for ignition tests in microgravity were obtained.

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Ammonia is expected to be not only as a hydrogen energy carrier but also as a carbon-free fuel. However, few studies of ammonia flame have been studied because of its lower combustion intensities. In this study, laminar burning velocity and Markstein length of ammonia/air premixed flames were experimentally evaluated from spherically propagating laminar flames. Equivalence ratios were varied from 0.7 to 1.3 and initial mixture pressure was set to 0.1 MPa. Spherically propagating laminar flames in a constant volume combustion chamber were observed by Schlieren photography with a high-speed camera. As a result, unstretched laminar burning velocities obtained in this study were slower than 8 cm/s for all examined equivalence ratios. The Markstein length increased with the increase in equivalence ratio. At the conditions of equivalence ratio of 0.8 and 0.9, Markstein lengths were negative. The numerical simulation using CHEMKIN-PRO with detailed reaction mechanisms were also performed. The reaction mechanisms must be improved in order to predict the unstretched laminar burning velocity of ammonia/air premixed flames.

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Homogeneous Charge Compression Ignition (HCCI) engines are being widely researched today, having attracted considerable interest for their low emissions and high efficiency. However, HCCI engines have a narrow range of stable operation owing to the occurrence of extremely rapid combustion at high loads and misfiring at low loads. The results of previous studies have shown that the application of exhaust gas recirculation (EGR) has the effect of moderating the combustion process by suppressing the occurrence of rapid combustion. The present study examined the effects of the engine speed and the EGR rate on HCCI combustion. The results revealed that the scavenging temperature rose and the ignition timing advanced with increasing engine speed. As a result, rapid combustion tended to occur because of a higher maximum pressure rise rate (dP/dt_<max>). It was also observed that when EGR was applied to moderate combustion, the rapidity of combustion did not increase even when the engine speed was raised.

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With the aim of designing a homogeneous charge compression ignition (HCCI) engine and also considering the range of prediction model, it is necessary to avoid the operation in lower combustion efficiency and generating noise. In this study, prediction models of the rate of pressure rise and cyclic variation were considered. As a result, it was clarified that rate of pressure rise is predicted by amount of injected fuel, ignition timing and combustion duration. It was also clarified that there is the good correlation between the rate of pressure rise and cyclic variation, and the proposed prediction model of pressure rise rate is also useful to predict the cyclic variation.

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This paper presents a simplified model of Homogeneous Charge Compression Ignition (HCCI) engine, which is suitable for controller synthesis. There are several control strategies to achieve stable HCCI operation, and here the exhaust rebreathing strategy is applied. To capture the key features of the rebreathed HCCI engine and make it simple enough for controller synthesis meanwhile, a simple control-oriented model is proposed.

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To predict ignition timing and combustion duration of HCCI combustion, it is necessary to consider inhomogeneity of pre-mixture such as O_2, Fuel, and temperature. Usually, CFD (Computational Fluid Dynamics) is applied to predict the inhomogeneity. However, the calculation load of CFD is heavy to use as the on-board model. In this study, a simple prediction model for ignition timing and combustion duration of HCCI combustion is developed, which can consider inhomogeneity of pre-mixture. PDF of EGR gas is employed to express the influences of inhomogeneity of O_2 and temperature in pre-mixture. This model is confirmed by comparing with the experiment result of the HCCI test bench. As a result, the predictability of this model achieves around 50% for plus minus 1.5 deg. of ignition timing and combustion duration.

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Ignition behavior of dual fuel HCCI combustion is affected by low temperature oxidation reaction. In this study, the behavior of low temperature oxidation reaction when iso-octane is mixed with n-heptane was investigated by engine experiments and chemical kinetic analysis. The engine experiments show that iso-octane apparently has little influence on heat release in low temperature reaction. From chemical analysis, this is because iso-octane reacts with OH radicals to suppress low temperature reaction of n-heptane while the low temperature reaction of iso-octane itself is activated to cover the loss of heat release in n-heptane reaction.

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Homogeneous charge compression ignition HCCI engine, are possible to increase the thermal efficiency with minimum emissions of NOx and PM. However, the problem, of difficult in ignition timing control and, the narrow operating range are yet to be resolved. Intake pressure boosting has been performed to raise the high load limit of HCCI, and it was found that the boosting has an effect to increase ignition stability. In this study, explosion limit in the temperature-pressure diagram is investigated, since the limit curve reflects the ignition reaction mechanism of fuels changing with pressure range. Ignition of n-heptane, iso-octane, and toluene were simulated by using a detailed chemical reaction kinetics model, and explosion limit curves of each fuel were created. A measure of ignition instability is proposed in this study. It is defined as a shift of ignition delay time divided by a shift of initial temperature when the temperature and pressure are shifted according to an adiabatic line. It was found that this instability index is reduced in the region of low-temperature heat release for n-heptane and iso-octane, whereas toluene showed constant instability index throughout the pressure range investigated.

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The present study investigated the effect of supercharging in the operation of a small single cylinder DI diesel engine equipped with a conventional jerk type injection system. The experiments used three kinds of fuels: rapeseed oil methyl ester, soybean oil methyl ester, and JIS No.2 diesel fuel, and the boost pressure was from 100 to 140 kPa (absolute pressure) changed with a Roots blower. The influence of the boost pressures on the engine performance, combustion characteristics, and exhaust emissions were examined. The results showed that at high loads, the brake thermal efficiency increased with increasing boost pressures while the smoke and CO emissions decreased significantly. It was established that compared with ordinary diesel fuel, all of the investigated biodiesel emission characteristics other than the NOx emissions were superior.

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