The growth and collapse of a bubble under a floating body are studied using the boundary element method. The toroidal bubble dynamics and the translation of floating bodies are taken into consideration. It is shown that when the mass of a floating body is sufficiently heavy, the bubble behavior is similar to that near rigid boundaries : the bubble translates toward the floating body, and the liquid jet threads the bubble surface in the final stage of the collapse. On the other hand, when the mass is moderate, the bubble collapses at the initial position without translation. The heavier the mass of a floating body becomes, the larger the bubble translation toward the body becomes, and thus the higher pressure is induced at the bottom of the body due to the impact of liquid jet. The results also show that the analysis with Kelvin impulse is effective in evaluating the bubble translation under floating bodies.

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New type of cavitation instability was observed in the inducer of fuel turbopump of H-II A rocket LE-7 A engine. This instability occurred at a small cavitation number at which the head of the inducer starts to decrease, and its propagation velocity ratio was about 0.5. In the present study, this cavitation instability is analyzed theoretically by using a cavity model with a cavity wake. The model can predict the head decrease due to cavitation (choke by cavitation) and also the positive slope of performance curve as observed in experiments. A stability analysis predicts a mode with the propagation velocity ratio of 0.5∼0.7 within the operating range where the performance curve has positive slope.

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This paper describes an investigation by numerical simulation and experiment on the structure and characteristics of the multiple shock waves and turbulent boundary layer interaction, that is, pseudo-shock wave in a Mach 2 two-dimensional channel. The numerical simulation was carried out with Harten-Yee's second-order accuracy TVD scheme and Baldwin-Lomax's algebraic compressible model for turbulent flows. Good agreement between the numerical analysis and the experiment for the shape of the shock train of the pseudo-shock wave and the wall pressure distribution along the channel was obtained. Based on this agreement, the flow quantities, which are very difficult to obtained by experiment, were analyzed by numerical simulation. These analyses are very valuable for understanding of the detailed structure and characteristics of the pseudo-shock wave. The study conditions are M_∞≅2.0 (free stream Mach number), Re_∞=2.5×10⁷m^-1 (unit Reynolds number), δ_∞/h=0.25 (flow confinement), respectively.

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As for transonic compressor cascades, the movement of shock waves in the flow passage affects the aerodynamic characteristics, that is, cascade flutter characteristics, because it introduces large pressure fluctuations on the blade surfaces. Therefore, it is necessary to clarify the characteristics of shock wave movement in the flow field. However, there are few studies about the characteristics of shock wave movement in the transonic compressor cascade oscillating in the pitching mode. To make sure the characteristics of shock wave movement in the flow passage of transonic compressor cascade, we constructed a high-speed photographing system combined with a Shlieren optical unit. The photographing concept is based on the fact that the shock wave movement following the blade oscillation is periodic. From the pictures taken with this system, the characteristics of shock wave movement in the flow passages of the transonic linear compressor cascade are analyzed in the range from 0Hz to 300Hz of one blade oscillation frequency.

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Translational motion of bubbles and particles in a cellular flow (i. e., a steady Taylor-Green vortex) is numerically investigated for various dimensionless parameters : density ratio "ρ^*", Stokes number "St" and drift velocity in quiescent fluid "W^*". The relaxation time "T^*" is estimated from the numerical results of the temporal evolution of the particle velocity. T^* for St>O(1) is approximately proportional to St⁺¹, while that for St<0(1) is to St^-1. The effect of St on the mean velocity "(V^*)^^^-" and the fully developed particle distribution strongly depends on ρ^* and W^*. For the heavier particle (ρ^*>1) with the small drift velocity (W^*<0(1)), the bifurcation of the particle distribution is observed as increasing St, due to the non-linear effect from the fluid to the particle. The bifurcation behavior is well correlated with the scattering profile of (V^*)^^^-. For the heavier particle with the large drift velocity (W^*>0(1)) or the bubble (ρ^*=0), such kind of bifurcation behavior is not observed. For bubbles with small W^*, they accumulate in the center of the vortex and drift motion does not occur.

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The boundary layer along a wind-tunnel contraction nozzle is investigated in detail using hotwire anemometry and flow visualization method. It is found that Gortler vortex system exists and develops in the concave wall region of the contraction nozzle. In spite of the flow acceleration by the contraction the distrubance enhanced by the Gortler vortex system travels down even to the test section. We found that this disturbed region at the test section is more than 25% of the cross-sectional area independent of the mean flow velocity. This is due to the large vertical scale of the Gortler vortex system in the concave wall region. This result shows the effects of the Gortler vortex system should be taken into consideration in designing a wind-tunnel contraction nozzle.

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The general goal of this study is to construct the closed loop control system of the reattachment process in a backward facing step flow by a row of the vortex generator jets. It is necessary to examine the dynamic characteristics of the injection jet on the reattachment process in the design of the control system. The coherence and the frequency transfer characteristics between the injection jet and the near-wall flow in the reattachment region are examined in the open-loop system. The result shows that the coherence between the jet velocity and the surface static pressure is higher than that with the surface friction velocity and the surface static pressre has better characteristics of the frequency transfer gain at the streamwise station of X/H>7. A step response of the near-wall flow is also conducted in order to find transient characteristics. It is found that the damped oscillation occurs in the surface static pressure immediately after a step change in the jet velocity.

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The dependence of mean flow and turbulence statistics on the non-dimensional parameters, the Mach number and the Reynolds number, is investigated using direct numerical simulation (DNS) of the low-Reynolds number compressible turbulent channel flow between isothermal walls. The Mach number M is based on the bulk velocity and sound speed at the wall. The Reynolds number Re is based on the bulk density, bulk velocity, channel half-width, and viscosity at the wall. Five computational cases are considered. The computational cases of Re=2000 with M=1.0, 1.25 and 1.5 are Cases A, B and C, respectively. The computational cases of M=1.5 with Re=2 000, 2500 and 3000 are Cases C, D and E, respectively. The main results of this report are as follows : (1) As M increases, the semi-local friction Reynolds number based on the local density and viscosity, semi-local friction velocity, channel half-width becomes larger in y^*&le;3 and smaller in y^*&gt;3, where y^* is the semi-local wall unit. (2) The mean dilatation profile depends on Re and M, even if the variable property effect is taken into account. (3) The region where the compressibility affects on the near-wall asymptotic behavior of wall-normal velocity intensity becomes wider with the increase of M and the decrease of Re.

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In the second report, the dependence of the energy exchange and Reynolds stress transfer on the non-dimensional parameters, the Mach number and the Reynolds number, is investigated using the DNS data of the low-Reynolds number compressible turbulent channel flow between isothermal walls. The Mach number M is based on the bulk velocity and sound speed at the wall. The Reynolds number Re is based on the bulk density, bulk velocity, channel half-width, and viscosity at the wall. The main results of this report are as follows : (1) The absolute values of the production and dissipation terms of the turbulent kinetic energy decrease with the increase of M and increase with the increase of Re. These terms are more sensitive to Re than M. (2) The absolute value of the pressure work decreases with the increase of M because of the decrease of the mean pressure, while it increases with the increase of Re because of the increase of the absolute value of the mean dilatation. The pressure-dilatation correlation term has a slight contribution to the energy transfer and is almost independent of M and Re. (3) The absolute value of the pressure-strain correlation term decreases with the increase of M and increases with the increase of Re. (4) The dependence of the turbulence intensities of M and Re is explained by using the budgets of the transport equations of the Reynolds stresses.

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Direct numerical simulation of coupled air-water flow mass transfer was carried out by employing the Eulerian and Lagrangian approaches at moderate and high Schmidt numbers from 1 to 1000. Three different flow conditions were chosen, i. e., the Reynolds numbers of gas and liquid phases, which were based on the interfacial friction velocities and depths, were set to be 150, increased to 300 only in the gas phase, and then 300 in both phases. In the liquid phase, the correlation coefficient between the scalar and the normal velocity fluctuation near the interface is found to be high (∼0.5) even at high Schmidt numbers. Quasi-streamwise vortices, whose velocity and length scales are determined by shear units, penetrate a very thin concentration boundary layer and govern the interfacial mass transfer. The resultant mass transfer rates are almost independent of the Reynolds number and inversely proportional to the square root of the Schmidt number of the liquid.

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The large-scale flow motions observed at or above the logarithmic layer of fully developed turbulent channel flow were investigated for a Reynolds number of 590 and 1180 defined by the friction velocity and the channel-half width. Large Eddy Simulation was adopted in this study as a numerical tool, considering the fact that sufficiently large analysis region and high Reynolds-number condition were required for the reproduction of the large-scale motions. The structure of the large-scale motions is similar to the fine-scale organized structures in the sense that streamwise velocity fluctuation shows streaky patterns, but their streamwise and spanwise sizes reach about three times and twice as large as the channel-half width respectively. Contrary to the fine-scale organized structures in the vicinity of the wall, these large-scale motions were found to obey the outer-layer scaling, independent of the Reynolds number tested here.

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The acoustic waves emitted from a circular cylinder are simulated by the lattice Boltzmann method using a two-dimensional thermal compressible lattice BGK model. The acoustic pressure field shows its dipole-like feature, and the frequency is synchronized with the Karman vortex shedding. The pressure also decays as a function of the square root of distance, and the relationship between the acoustic pressure and the Mach number of the flow coincides with the analytical prediction.

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The sound characteristics of the transmitted waves through the curved duct with a splitter have been studied for various lengths and locations of the splitter in addition to the effect of mean flow in the duct. A finite difference method for a linearized Euler equation is performed to obtain the sound pressure level (SPL) and time-averaged intensity together with acoustic energy flux vector and time history of sound pressure. The present study shows that the level of the transmitted waves can be reduced remarkably at a particular length to yield the great insertion loss, however the variation of the splitter location has little effect on the insertion loss. The present result also shows that the instantaneous acoustic energy flux vector make clear the characteristics of the sound field, compared with the time-average intensity.

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A new procedure has been developed for optimizing the geometry of the supersonic wind tunnel variable nozzle by using computational fluid dynamics (CFD) technologies. In this procedure, the nozzle geometry is optimized by a slight displacement of each jack that supports the nozzle plate from the initial position so that the Mach number deviation from the uniform flow in the measuring region is minimized. The optimum nozzle geometry is gained in a few CFD cases by using the linearity between the jack displacement and the effect on the flow pattern by the displacement. This procedure is applied to Mach number 3.0 and 4.0 nozzles, and improvement of the flow patterns in the measuring region was seen in CFD analyses.

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The optimization procedure of the supersonic wind tunnel nozzle geometry is verified in the National Aerospace Laboratory (NAL) 1m×1m supersonic wind tunnel. The procedure is carried out by a slight displacement in each jack of the variable nozzle from the initial position. Mach number distribution was obtained by measuring total pressure in the measuring region with a pitot rake. Mach number 2.1, 2.2, 2.3, 2.5, 3.0, 3.5, and 4.0 nozzle contours were optimized in this procedure, and Mach number deviation in the measuring region was reduced below 1.0% of mean Mach number in each nozzle contour.

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A Large-Eddy Simulation (LES) based on a finite-difference scheme is applied to stack gas diffusion of a turbulent boundary layer. A Flux-Corrected Transport (FCT) scheme is used to prevent a numerical oscillation and a negative concentration in the LES. Furthermore, a beta-Probability Density Function (PDF) model, which considers a Subgird Scale (SGS) concentration fluctuation, is applied to predict the detailed concentration statistics such as an instantaneous high concentration and an intermittency factor of the concentration in a coarse grid resolution. The validity of these methods is confirmed to compare the results of the LES with the wind tunnel measurements. The results show the predictions of the mean concentration and mean squared concentration fluctuation are in good agreement with the measurement and the present LES using the FCT scheme is applicable to the stack gas diffusion. The present method, which takes account of the concentration fluctuation, can exactly predict the instantaneous high concentration value and intermittent factor even in the coarse grid resolution.

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Flow measurements were made in an unshrouded centrifugal impeller by using a hot-wire anemometer for a flow rate corresponding to nearly zero incidence angle. The relative velocity, the dissipation and the turbulence kinetic energy were measured on seven cross-sectional planes along the rotating impeller passage. The results were investigated by correlating to a secondary flow in the passage. About the passage inlet, the regions of the velocity and total pressure with low values and the dissipation and turbulence kinetic energy with high values appear near the casing due to the effects of a passage curvature and a blade tip leakage. About the middle passage, such regions develop at the middle blade-to-blade of the casing side by the addition of a secondary flow to the tip leakage. About the passage outlet, the secondary flow weakens in the passage. However, such regions enlarge near the suction from the casing side because of the passagewise rotary pressure gradient.

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Three-dimensional natural convection of water near the density extremum within a horizontal annulus is studied numerically for three temperatures of the outer cylinder of 4, 6 and 8°C with the inner cylinder temperature maintained at 0°C. It has been found that owing to the density extremum water flows upward along both the inner and outer cylinder surfaces and downward in-between. It has also been found that in the case of T₀=6°C, a velocity field with two pairs of counter-rotating flow form in the upward vertical cross section parallel to the annulus axis, and the local Nusselt number distribution on the inner cylinder surface takes peak values at the locations toward which the counter-rotating flow conveys the higher temperature water heated by the outer cylinder, while in the case of T₀=8°C, a velocity field with counter-rotating flow in the cross section parallel to the annulus axis forms in the side and bottom regions, and the local Nusselt number distribution on the inner cylinder surface shows the corresponding peak values.

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An advanced co-generation system (ACGS) was built at Waseda university. The ACGS consists of a gas turbine system, a steam turbine system, an ammonia absorption refrigerator system, an ammonia-water mixture turbine system and an ice storage system. The energy taken out from each turbine system is used for power generation. On the other hand, the ammonia absorption refrigerator is used for the air-conditioning during the daytime in paralell with storing heat in the ice storage system in order to meet cooling demand during the nighttime. In this paper, it is discussed that the operational planning of the bottoming stage of ACGS maximizing its electric power. And the relationship between the component capacity and the operational planning is also discussed by studying an optimal solution of the dual problem, the so called "shadow price".

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Most of the past solar-powered heat engines have been aiming at operating under very high temperature and high pressure. For example, solar Stirling engine is operated at over 700∼800 degrees Celsius and at high pressure exceeding 10MPa. However, in order to obtain such a high temperature and high pressure condition, concentrating collector with large concentration ratio is inevitable. Also sun tracking device was compulsory to achieve high thermal efficiency. This direction requires high cost of the product, and brings low thermal efficiency, which loses competitiveness in the solar market. In this article, the unique solar Rankine cycle engine using displacement-type scroll expander is proposed. The proposed solar Rankine cycle engine has the following features ; 1) The system consists of very simple components similar to the airconditioner. 2) The operational temperature is very low (100∼300°C). 3) The thermal efficiency based on solar radiation is supposed to be about 15%, which is at least twice the conventional photovoltaic (PV) system.

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The purpose of this paper is to explain the optimum extraction condition of Uehara cycle under Ocean Thermal Energy Conversion (OTEC). We studied about the optimum condition of extraction which makes cycle efficiency highest, because cycle efficiency depends on condition of extraction. And we studied about influence of the performance of the regenerator to the cycle efficiency.

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If a flow obstacle such as a spacer is set in a boiling two-phase flow within an annular channel, where the inner tube is used as a heater, the temperature on the surface of the heater tube is severely affected by the existence of the spacer. In some case the spacer has a cooling effect, and in the other case it causes the dryout of the cooling liquid film on the heating surface resulting in the burnout of the tube. The burnout mechanism near the spacer, however, is not still clear. In the present paper we focus our attention on the occurrence of the burnout near a spacer, and discuss the occurrence location of dryout and burnout and the relation between the occurrence of burnout and differential-pressure fluctuation characteristics caused by the disturbance waves passing by a spacer.

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By using alcohol such as ethanol and methanol as the carbon source, a new simple catalytic chemical vapor deposition technique to generate high-purity single-walled carbon nanotubes at low temperature is demonstrated. Vapor phase alcohol was supplied over Fe/Co catalyst supported with Zeolite in an electric furnace. The blackened sample was analyzed by resonant Raman spectroscopy, transmission electron microscopy and scanning electron microscopy. Because of the etching effect of decomposed OH radical attacking carbon atoms with a dangling bond, impurities such as amorphous carbon, multi-walled carbon nanotubes, metal particles and carbon nanoparticles are completely suppressed even at relatively low reaction temperature such as 700-800°C.

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Numerical analyses by DDM (Discrete Droplet Model) are carried out to clarify the effect of initial conditions on the fuel spray formation process for a swirl-type injector. Two kinds of initial conditions are tested ; one is empirical expressions and the other is the results obtained by VOF model that is used to simulate the two-phase flow inside the injector to give the liquid film formation process outside the nozzle. As a result, calculations using the results of VOF model for the initial conditions showed a better agreement with experiments than using empirical expressions. Important factors as initial conditions were found to achieve good predictions.

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Since fuel spray has spatiotemporally inhomogeneous structure, spray ignition is treated as probabilistic phenomenon. Consequently, it is aimed to clarify the effect of inhomogeneity, especially spatial inhomogeneity, on ignition probability. Methanol mono-dispersed spray/Vapor/Air mixture was ignited by a discharged ignition system. A large number of ignition tests were carried out for two conditions, which time-average fuel spray concentrations are different but spatial inhomogeneities of both sprays different. Results obtained from these ignition tests were compared each other under same instantaneous spray concentration. Spatial inhomogeneity of fuel spray is reprenented by inhomogeneity index, which represents the relative intensity of inhomogeneity to that of random state. As a result, ignition probability is different though instantaneous concentrations are same since spatial inhomogeneity of fuel spray is different in both conditions. In addition, the maximum value of inhomogeneity index of both conditions were compared each other. The maximum value of successful ignition cases become almost same. This fact suggests the existence of optimum intensity of spatial inhomogeneity for ignition.

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Experimental and Numerical studies are conducted on unsteady natural convection in a multilayered porous system heated from below and cooled from above. The attractors in phase space, and Lyapunov exponents and correlation dimension are experimentally and numerically examined for a high Rayleigh number. The numerical chaotic behaviors are rather well compared with the experimental results. The spatial distributions of Lyapunov exponents are examined for a high Rayleigh number. It is shown that there may exist a convective mode with high entropy generation which suppresses chaotic behaviors.

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To investigate effects of ambient atmosphere on flame spread, an experimental study has been conducted. The downward flame spread over solid fuel has been examined in a combustion chamber with a vertical duct to obtain uniform ambient atmosphere. The flame spread rate is measured with constant inflow velocity. Two kinds of paper sheet are used as samples. Ambient temperature is increased up to 150°C, and oxygen concentration is reduced to examine the diluent effect, adding carbon dioxide and nitrogen to the ambient air. The gas temperature is measured by thermocouples. Results show that, the flame spread rate is decreased with a smaller oxygen concentration, resulting in smaller heat flow into the preheat region, Q. Diluent effect of carbon dioxide is larger than that of nitrogen to reduce flame spread rate, with larger limiting oxygen concentration. In the gas temperature distribution, the maximum temperature is located around the flame zone, which is defined as the flame temperature. As oxygen concentration is decreased, the flame temperature is reduced. Hence, as the flame temperature is decreased, the heat flow into the preheat region is resultantly smaller. The temperature where the flame can not propagate is almost constant for all cases. Therefore, at extinction limit, the flame temperature is low so that the flame spread can not be supported due to smaller Q.

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In this study, the model for flame spread over solid fuel is investigated. To re-examine the analytical solution by de Ris, our experimental data on flame temperature and flame spread rate are used, which were obtained by the measurements of downward flame spread over filter paper sheets in uniform ambient atmosphere diluted with either N₂ or CO₂. In the analytical models, the assumption has been usually adopted that the reaction rate is infinite and steady state is achieved. Then, in our previous experiments, oxygen concentration was reduced at elevated temperature up to 150°C to confirm the limitation of analytical solution. Results show that, when the oxygen concentration is relatively high, the agreement of flame spread rates of analytical solution and experimental data is observed. However, decrease of the oxygen concentration reduces the flame temperature, and makes the flame spread unstable at some points. In this case, the analytical model can not predict the flame spread. This is explained by the fact that the assumptions for infinite reaction rate and steady solution are invalid.

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An attempt has been made to examine the flame-flow interaction in turbulent premixed flames in a reaction sheet regime. Vectors of the flame-front movement and gas velocity have been simultaneously measured by use of a two-color, four-beam LDV system and a three element electrostatic probe at two positions in a turbulent flame brush, i. e., on the center line and off axis positions. On the center line, velocity vectors of the flame-front movement are distributed symmetrically wih the burner axis, independently of whether the flame front passes the measuring position in the burnt-to-unburnt or unburnt-to-burnt direction. Off axis, velocity vectors of the flame-front movement are distributed toward the burner axis when the flame front passes the measuring position in the unburnt-to-burnt direction. They are distributed away from the burner axis, when the flame front passes the measuring position in the burnt-to-unburnt direction. When the flame front passes the measuring position in the burnt-to-unburnt direction, the axial component of the gas velocity is smaller in the unburnt mixture. When the flame front passes the measuring position in the unburnt-to-burnt direction, on the other hand, the axial component of the gas velocity is smaller in the burnt gas.

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An attempt has been made to examine the flame-flow interaction in turbulent premixed flames in a reaction-sheet regime. Vectors of the flame-front movement and gas velocity have been measured simultaneously by use of a two-color, four-beam LDV system and a three-element electrostatic probe at two positions in a turbulent flame brush, i. e., on the centerline and off axis. Change of gas velocity across the flame front differs whether the flame front passes in the unburnt-to-burnt or burnt-to-unburnt direction. When the flame front passes in the burnt-to-unburnt direction, the normal component of the gas velocity to the flame front decreases across the flame front, while the parallel component does not change across the flame front. On the other hand, when the flame front passes in the unburnt-to-burnt direction, the normal component of gas velocity decreases across the flame front. The parallel component increases in the opposite direction to that of the flame front movement.

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Direct in-cylinder injection of reaction suppressors was effective to successfully control igition timing and suppress rapid combustion in a premixed charge compression ignition (PCCI) engine. The experimental results showed that the reaction suppressor injection significantly recuced the heat release at low-temperature oxidation reactions which suppressed an increase in the charge temperature after the onset of low-temperature oxidation reactions and in the rapid combustion. Chemical kinetic modeling showed a reduction of OH radical concentration before the onset of low temperature oxidation with injection of suppressors. Among the various ignition suppressors, alcohols had a greater impact on OH radical reduction resulting in stronger ignition suppression than other oxygenated and unoxygenated hydrocarbons, water, and hydrogen. The mechanism of the low temperature oxidation suppression with alcohols was considered to be caused by the consumption of OH radical reacting with hydrogen atom in alcohol molecules.

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In order to inventigate the soot formation process in a diesel spray flame, simultaneous imaging of soot precursor and soot particles in a transient spray flame achieved in a rapid compression machine was conducted by laser-induced fluorescence (LIF) and incandescence (LII) techniques. 3rd harmonic (355nm) and fundamental (1064nm) laser pulses from single Nd : YAG laser, between which a delay of 44ns was imposed by 13.3m of optical path difference, were used to excite LIF due to soot precursor and LII due to soot particles separately in the spray flame. The LIF and the LII were separately imaged by two imageintensified CCD cameras with identical detection wavelength of 400nm and bandwidth of 80nm. The LIF due to soot precursor was mainly located in the central region of the spray flame between 40 and 55mm (270 to 370 times nozzle orifice diameter d₀) downstream from the nozzle orifice. The LII due to soot particles was observed to surround the soot precursor LIF region and to extend downstream. First appearance of the LIF due to soot precursor in the spray flame preceded the appearance of the LII due to soot particles. The intensity of the LIF due to soot precursor reached its maximum immediately after rich premixed combustion. In contrast, the intensity of the LII due to soot particles increased gradually and reached its maximum after the end of injection. Measured LIF spectrum of the soot precursor in the spray flame was very broad and showed no apparent spectral structure.

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Dual fuel natural gas engines have been studied for the purpose of near future engine. This study focuses on the effect of early injection of light oil and exhaust gas recirculation (EGR) fueled with methane from an inlet pipe on characteristics of combustion and exhaust emissions. The injection timing was changed from TDC to 50 degrees before the TDC. In the early injection timing, smoke was never seen and hydrocarbons were smaller compared with those at the normal injection timing. However, the combustion becomes too early to obtain an appropriate torque when the equivalence ratio increases. Then, moderate nitrogen dilution was very effective to retard the combustion with lower NO_X, higher thermal efficiency and almost the same hydrocarbons and carbon monoxide. And it was found that the engine operates even under the condition of stoichiometric mixture.

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In order to contribute to the life assessment of the first stage rotor blade of a power generation gas turbine, analysis of transient temperature distribution at start-up and shutdown including an emergency trip were conducted by thermal conjugation inside and outside the blade. Characteristic diagrams simulating an plant were used for the numerical predictions. The distinctive features of the temperature distribution of the blade were predicted in each operation process. Those were influenced by the characteristics of the heat transfer, varying with the operation load range. The temperature distribution of the blade remained similar in the operation for over half load. In the operation at half and no-load conditions, especially in the emergency stop process, the feature of the temperature distribution markedly changed owing to unsteadiness of the heat conduction inside the blade. The present predictions of the transient distributions of the blade temperature made it possible to put the analytical life assessment of the gas turbine blade into practice.

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A hybrid system based on a micro gas turbine (μGT) and a high temperature fuel cell, i. e., molten carbonate fuel cell (MCFC) or solid oxide fuel cell (SOFC), is expected to achieve a much higher efficiency than conventional distributed power generation systems. In this paper, a cycle analysis method and performance evaluation of a μGT-MCFC hybrid system, of which power output is 30kW, are investigated to clarify its feasibility. A general design strategy is obtained that decreasing fuel input to a combustor and a higher MCFC operating temperature lead to higher power generation efficiency. A higher recuperator temperature effectiveness and steam-carbon ratio moderate requirements for the material strength of a turbine. It is also confirmed that a μGT-MCFC is much feasible to a μGT-SOFC in terms of its moderate heat-resistance of turbine and recuperator materials. In addition, employing a combustor for complete oxidation of MCFC effuluents without additional fuel input, i. e., a catalytic combustor, the power generation efficiency of a μGT-MCFC is achieved to over 60% (LHV).

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The purpose of this study is to investigate the effect of supplying 0 radicals generated by ArF excimer laser irradiation on the ignition of a CH₄-Air mixture. The laser-induced ignition experiment was performed in CH₄-air mixtures using a Rapid Compression Expansion Machine (RCEM). To study the ignition process, the pressure in the combustion chamber was monitored and OH^* chemiluminescence images were taken using a high-speed camera. The laser-induced ignition was classified 3 patterns ; point ignition, line ignition and ignition near the window. These ignition patterns were decided by the magnitude of the absorption cofficient of oxygen and the ignition types and locations were predictable if the absorption coefficient was known. Then, we evaluated the advantages of applying the laser bulk ignition technique by comparing the pressure profiles with high laser power and with minimum laser ignition power. It was considered that 0 radical generation along the laser beam path caused to reduce the ignition delay and enhance the combustion rate after the ignition.

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