The gas ingestion phenomena of a viscoseal, which is a type of noncontact seal, are described. A screw shaft, 40mm in diameter and 145mm in length, is horizontally set in the casing, which is 40.4mm in inner diameter. Sealant, which fills the 0.2mm radial clearance between the screw shaft and the housing, is pressurized by the screw-pump effect. Flow visualization and pressure measurements are performed in the viscoseal. Changes in the gas-liquid interface are found to be different from the ingested gas motion depending on the rotating angle of the screw shaft. Most of the ingested gas bubbles are observed in the screw groove when the screw shaft is rotating in the direction of the gravitational force. In contrast, the ingested gas bubbles are observed both in the screw groove and on the screw land when the screw is rotating in the opposite direction to gravity. Also, the ingested gas bubbles are subdivided with increasing pressure in the sealant along the screw axis. Both the formation of the air-liquid interface and the ingested gas motion are influenced by the circumferential pressure differences in the sealant, which are both experimentally and theoretically observed. As a result, it is confirmed that the ingested gas deformation is affected by both the direction and the force of the pressure in the sealant.

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The breaking of a water solitary wave over a sloping-step geometry is studied both experimentally and numerically. There are three parameters for this breaking phenomenon, but we find that the breaker type can be sorted primarily by a single parameter, i.e., the ratio of the solitary-wave height to water depth above the step. As this parameter increases, breaker type changes from spilling to plunging and finally to collapsing if the sloping angle of the step is not small (30° or greater). If the sloping angle is small (about 10°), breaker type changes from spilling to plunging but no collapsing occurs. Flow velocities in the water measured by PIV show that the mechanism of collapsing breaker is quite different from that of spilling and plunging breakers.

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Some aspects of the transient cavity formed by the impact of the magnet-magnetic fluid systems on the free surface of water were analyzed by a digital high speed camera system. The projectile system was composed of a permanent NdFeB magnet and kerosene-based magnetic fluid HC-50. The spherical and the cylindrical permanent magnets were used in the experiment. The effect of the magnetic fluid adsorption on the cavity formation was clarified. The effect of the alternating magnetic field on the magnet-magnetic fluid projectile was also revealed. The alternating magnetic field was generated by applying alternating current voltage to the Helmholtz coil. The rotary motion of the projectile was generated by the applied alternating field. The applying magnetic field to the magnet-magnetic fluid projectile led to the complicated surface of the cavity.

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The fuel spray for automobile engine includes multi-scale free surfaces; liquid films formed at the fuel-injector outlet, ligaments generated by the liquid-film breakup, and droplets generated from the ligaments within air/fuel mixture region. To simulate multi-scale free surfaces in the fuel spray of an injector for automobile engine, we combined a liquid-film-breakup simulation and an air/fuel-mixture simulation. The liquid-film breakup near the injector outlet was simulated by using a particle method, and the air/fuel mixture after the liquid-film breakup was simulated by using a "discrete droplet model" (DDM). Distributions of droplet diameters and velocities, calculated in the liquid-film breakup simulation, were used as the injection condition of DDM. We applied our new method to simulate the spray from a collision fuel injector. The simulation results were verified by comparing them with measurements. The liquid-film breakup near the injector outlet and the behavior of the air/fuel mixture qualitatively agreed with the measurements. We found that our new method was useful to the fuel-spray simulation for automobile engines.

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The flow field near a moving contact line was measured with the particle imaging velocimetry technique. The test liquids of pure water, ethylene glycol (EG), dimenthyl sulfoxide (DMSO) and polydimethylsiloxane (PDMS) of which surface tensions range from 19mN/m to 72mN/m were used with the solid materials of glass, polymethylmethacrylate (PMMA) and polytetrafluoroethylene (PTFE). The combination of these materials varied the contact angle from zero to 90 degrees. Each solid material was withdrawn from each liquid into Ar gas atmosphere at a constant speed of 0.62mm/s. The observed flow fields were qualitatively different from the theoretical ones obtained with a linear model when the test liquid was either of water, EG or DMSO with the contact angle less than 90°. It is found that, for such flow fields, the viscous tangential stress on the gas-liquid interface estimated for the liquid phase is much larger than that for the gas phase. The stress in the liquid phase forces the liquid on the interface to flow toward the contact line. The Marangoni stress induced by inhomogeneous distribution of slight amount of impurity (surfactant) on the gas-liquid interface is the most presumable mechanism which compensates for the difference between the viscous stresses for the both phases on the interface.

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The electro-void fraction meter (Capacitance type meter) was applied to higher pressure conditions of 18MPa than BWR operating conditions of 7MPa. The void fraction measurement system has been developed including the electrodes of void fraction measurement, instrumentation cables with mineral insulation and simplified electric circuit to provide good signal-to-noise ratio. It satisfied the performance of thermal and pressure resistance and electric insulating capacity. Calibration function for high temperature and high pressure conditions was confirmed through calibration test with 37-rod bundle against datum 19-rod bundle by the quick-shut valve method respectively under 2MPa conditions. It was confirmed that the measured data were consistent with those measured by the quick-shut valve method.

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A new coal devolatilization model employing a tabulated-devolatilization-process (TDP model) is developed, and its validity is investigated by performing a numerical simulation of a pulverized coal combustion field formed by a small non-swirling jet burner. In the TDP model, appropriate values of the devolatilization parameters, which are the ratio of volatile matter mass to coal particle mass and the pre-exponential factor and activation energy in the volatile matter evolution rate equation, are extracted from the devolatilization database. Namely, these devolatilization parameters are stored beforehand in the database for various temperature histories, and are valued for each coal particle depending on the actual individual particle heating rate in the pulverized coal combustion field. The predicted characteristics of the pulverized coal combustion field employing the TDP model are compared with those employing the conventional delolatilization model and the experiments. The results show that the coal particle velocities predicted by the numerical simulation employing the TDP model are in better agreement with the experiments than those employing the conventional model, with a slight increase in computation time. Since the TDP model can represent the devolatilization behavior at various particle heating rates, it is expected to facilitate the accurate numerical simulations of pulverized coal combustion fields under various combustion conditions.

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A numerical simulation of a pulverized coal combustion field formed by an industrial low-NO_x burner in a 100kg-coal/h test furnace is performed employing a tabulated-devolatilization-process model (TDP model), and its validity for a strong swirling flow field is investigated in detail. The predicted characteristics of the pulverized coal combustion field obtained from the simulation employing the TDP model are compared with those employing the conventional devolatilization model and the experiments. The results show that drastic differences appear between the gas flow pattern and coal particle behavior in the furnace for the TDP model and those for the conventional model. In particular, the recirculation flow behavior is strongly affected by the difference in the coal devolatilization model because of the difference in the volatile matter evolution rate. The comparisons with the experiments show that the TDP model is superior to the conventional model for predicting the pulverized coal combustion field in a swirling flow with recirculation.

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This paper discusses the Kirchhoff's law on thermal radiation. The logic of derivation of the law is reconsidered, first. Then, spectra of normal emittance ε_N and normal incidence hemispherical reflectance R_<NH> are measured on surfaces whose microstructure changes in a non-equilibrium experimental system to examine the validity of the complementary relation between ε_N and R_<NH>, which is the suggestion of the Kirchhoff's law. As the results of the examination, it is illustrated experimentally on a variety of surfaces that the complementary relation is valid within an experimental uncertainty. Provided this conclusion is admitted, the followings are suggested. If a surface is designed so that it does not reflect a narrow spectral region of radiation to any direction and reflects the other spectral regions of radiation much over the hemisphere, then the surface can be a new spectrally-functional emitter of radiation. It is also suggested that thermal radiation emitted at a surface is considered as the emission of plane waves at the surface rather than as the emission of spherical waves by electric dipoles.

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Measurement method of the interfacial thermal resistance (ITR) between a multi-walled carbon nanotube (MWCNT) and solid surface is developed by using a sub-micrometer Pt hot-film. Thermal application of CNTs is promising due to their very high intrinsic thermal conductivity. However ITR could be dominant in the total thermal resistance when CNT is used for heat dissipation devices. Therefore measuring ITR between CNT and solid material is important in order to determine the total thermal resistance. Though it is fundamental to understand the ITR in nano or atomic scale, there have been reported very few experimental approaches to measure the ITR due to technical difficulties. By using a MWCNT as a probe on the Pt hot-film, it is concluded that the ITR between MWCNT tip and SiO_2 surface is 1×10^6K/W, which is confirmed to be independent of contact pressure.

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To examine temperature of the local reaction zone of turbulent premixed flames, dependence of the emission by OH, CH and C_2 radicals obtained from hydrocarbon-air premixed flames on flame temperature has been examined. To detect weak emissions of C_2 radical, both spectrometer and amplifies were newly developed to achieve the signal-noise ratio of the newly developed system is two-digit higher than that of the conventional system. Measurements were made at various equivalence ratios in laminar premixed methane/air and propane/air flames, which have different flame temperatures. The chemiluminescence intensity ratio of 515nm/470nm bans of C_2, C_2^*(0,0)/C_2^*(1,0), in both methane/air and propane/air flames has a high correlation with flame temperature. The chemiluminescence intensity ratio of C_2^*(0,0)/C_2^*(1,0) has two branches for the flame temperature. i.e., as it increases, flame temperature increases, has maximum near the stoichiometry and decreases. The error in C_2^*(0,0)/C_2^*(1,0) measurement was within 3% for propane flames, within 6% for methane flames. It has been shown in the present study that temperature of the local reaction zone of premixed flames can be estimated by measuring the chemiluminescence intensity ratio of C_2^*(0,0)/C_2^*(1,0).

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Outwardly propagating hydrogen-air turbulent flames were studied at the equivalence ratios from 0.6 to 1.0 and the initial pressures from 0.10 to 0.50MPa. Turbulence intensity, u' was set to 0.80 to 1.59m/s. The Markstein number decreased for increasing pressures and for small equivalence ratios. The ratios of turbulent to unstretched laminar burning velocities at a constant Peclet number increased with increasing turbulence Karlovitz number and decreasing Markstein number at a constant pressure. This ratio of burning velocities increased with increasing pressure at the equivalence ratios of 0.6 and 0.8. At the equivalence ratio of 1.0, however, it did not increase with increasing pressure although the Markstein number reduced with pressure.

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Thermodynamic irreversibilities in a spray combustion process were evaluated at group combustion and single droplet combustion conditions. Two-dimensional governing equations for gaseous and disperse phase were solved by using numerical simulation, and one-step global reaction for n-decane was used as combustion reaction model. The entropy generation rate is introduced to quantify thermodynamic irreversivilities. The contribution by each factor of entropy generation rate, i.e. viscous dissipation, heat conduction, mass transfer and chemical reaction, was compared. In single droplet combustion mode and internal group combustion mode, chemical reaction become the dominant factor in entropy generation. The entropy generation rate due to chemical reaction was reduced at group combustion condition, and its behavior of reduction was determined by transient combustion states at center and outer of the spray region.

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To obtain the strategy for reducing NO_x emissions and pressure rise rate in PCCI-based diesel combustios, a fundamental study was performed on spray combustion with long ignition delays using a constant volume vessel. NO mass in the combustion chamber was measured with a total gas sampling method and heat release rate data were analyzed varing injection pressure, nozzle orifice size, ambient oxygen mole fraction and fuel ignitability. To cralify the fuel-air mixing conditions which provide reduced NO formation and maximum heat release rate, the data are plotted against the fuel mass fraction in a spray at ignition, which is proposed as an index of mixing progress. Based on the results, explanations are given for the difference of the trend between NO mass and maximum heat release rate.

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The effects of radiation on the unstable behavior of cylindrically expanding premixed flames at low Lewis numbers were studied by two-dimensional unsteady calculations of reactive flows, based on the diffusive-thermal model equation. When the Lewis number was sufficiently low under the adiabatic conditions, cellular flame fronts formed, which was due to diffusive-thermal instability. As the radiation loss increased, the front behavior became more unstable. This indicated that the radiation loss promoted the unstable behavior of flame fronts at low Lewis numbers. At sufficiently large radiation loss, several small flames were observed, which was in qualitative agreement with the experimental results under the low gravity conditions. Small flames appeared on the grounds that large curvature of flame fronts was necessary to keep high temperature against the radiation loss.

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