The quantum effect in the rarefied gas flow is studied by the direct simulation Monte Carlo method with the calculation of quantum mechanical scattering. The DSMC with quantum scattering and classical scattering are applied to the simulation of the highly expanded free jet of ⁴He gas in order to compare with the measured data. It is shown that the parallel temperature of quantum mechanical scattering is higher than that of classical scattering and the normal temperature of quantum mechanical scattering is lower than that of classical calculation. The parallel and normal temperatures for the classical scattering mechanics are in better agreement with the measured data than those of the quantum mechanical scattering. The discrepancy of parallel and normal temperature between the quantum calculation and the measured data are not more than 2K and 0.3K respectively. It is hoped, therefore, that more experiment may be made for detailed discussion.

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The variable hard sphere (VHS) and variable soft sphere (VSS) molecular models are extended to the molecular collision with quantum mechanical scattering. The total collision cross sections of the VHS and VSS models and softness coefficient of the VSS model are calculated for ⁴He and ³He gases with the Lennard-Jones potential. It is revealed that the VSS model has significant errors that the total cross section and softness parameter are diverged for collision energy ratio 0.05≲E/ε_LJ≲0.5. The efficiency of the VHS model for quantum mechanical scattering is examined for the simulation of velocity relaxation in a homogeneous space and free jet of ⁴He as compared with those of quantum calculation. The macroscopic quantities of VHS model such as density, velocity, and temperature profiles are in good agreement with those of quantum calculation, although there are some discrepancy between the VHS model and quantum calculation in the velocity distribution functions of the relaxation process.

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By means of a von Neumann linearized stability analysis, we analyze the numerical stability of thermal Lattice Boltzmann Methods for a 13 velocity hexagonal lattice and for 13 velocity square lattice. The LBM stability depends on the flow mean velocity, the temperature, the relaxation time, and the wavenumber. The stability boundaries are computed for varying the mean flow velocity, the temperature, and the relaxation time. Results common to these lattices are that as the relaxation time is increased, the maximum stable parameters increase monotonically until some fixed values. We also analyze the influence of a fictitious forcing term on numerical stability of the LBMs. The maximum values of stable forcing terms are shown as function of the BGK relaxation time for a 7 velocity hexagonal, a 13 velocity hexagonal, and a 13 velocity square lattices. In terms of numerical stability, we recommend that researchers use the thermal LB models in the region where the mean flow velocity is around 0.00 and the temperature is between 0.60 and 0.80.

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Molecular dynamics method is a technique to understand physical phenomena by tracing movements of particles from a microscopic viewpoint. Many algorithms have been proposed in order to solve a lot of physical problems. We investigate the property, accuracy, stability and calculation efficiency of seven representative algorithms : velocity Verlet, leap frog. 4 value Gear, Beeman, Runge Kutta, position Verlet and Tuckerman Berne. The Lenard Jones potential was used in this study. The velocity Verlet algorithm is useful for the problem under high density or low temperature conditions. The position Verlet algorithm is useful under high density or high temperature conditions. The Tuckerman Berne algorithm is useful under low density conditions. The Tuckerman-Berne algorithm has high stability and its calculation time is shortest in the algorithms used in this study. However, its precision is low. Therefore, we need to choose the optimum algorithm in consideration of the state of the focused system.

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On this paper, analysis scheme is developed which can apply complex shapes easily with unstructured mesh (triangle mesh on 2D, tetrahedron mesh on 3D) and can deal with unsteady shock waves accurately and with low memory using adaptive mesh refinement. To verify the efficiency of this scheme, shock tube problem and analysis of unsteady shock waves around cylinder and sphere was done. These analyses show that adaptive mesh refinement plays the great role for low memory consumption, and this analysis scheme has shape flexibility, accuracy and efficiency of computer memory.

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This paper describes an algorithm and its application of a coupled fluid/structure (CFS) problem on an incompressible unsteady flow and a perfect elastic body in a manner of the loosely coupling. The present method proceeds with exchanging the data between the fluid analysis and the elastic analysis. Here, we examined a two dimensional elastic circular cylinder in the uniform flow as an example of CFS problem and compared the deformation of surface of circular cylinder and the influence of the flow drag due to elasticity with those of the rigid body. Our result indicate that the loosely coupling method is effective for the problem between the incompsressible unsteady flow and the perfect elastic body and furthermore confirmed that the drag reduction can be achieved due to the interaction between fluid and elastic body.

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In this paper, the distribution of dipole sound sources at the bogie section of high speed trains are predicted numerically. The three-dimensional unsteady flow around a train is solved by the large eddy simulation technique. The time history of vortices show that the unstable shear layer separated at the leading edge of the bogie section sheds vortices periodically. These vortices travel leeward while growing to finally impinge upon the trailing edge of the section. A compact Green's function adapted to the shape is also given numerically by solving Laplace equation. By coupling the instantaneous flow properties with the compact Green's function, the distribution of dipole sources is obtained. The results show that a strong dipole source is generated at the trailing edge of the bogie section where the shape changes greatly and the variation of flow with time is also great. On the other hand, the bottom of the bogie section where the shape does not change, or leading edge and boundary layer where a variation of flow in time is small, can not generate a strong dipole source.

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It is well known that shock wave formed in an exhaust pipe of a reciprocating engine generates very loud noise when it is discharged from the pipe end into atmosphere. However, there are few reports that describe flow field formed after discharge of the shock wave. In the flow field vortex ring and underexpanded jet appear behind the shock wave. Also, it is possible that vortices moving along shear layer of the jet interact with the shock wave formed in the vortex ring which is generated by so called 'convergent divergent nozzle effect'. The interaction may become noise source. In the present study, we describe the jet structure and the process of the noise generation experimentally or numerically. In the experiment pressure measurement in a pipe, visualization, sound pressure measurement and fluctuating static measurement of the jet are made. In the numerical study we assumed that flow through the pipe should be 1 dimensional and it was solved by using 3rd order MUSCL TVD scheme. Moreover, for flow field generated downstream of the pipe end, 5th order MUSCL TVD scheme is employed in order to capture sound wave.

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Upon the strong demand of compactness of scroll compressor, compressors become to be driven with larger speed, and gas velocity trends to increase in the suction path. According to this trend, the accurate estimation and reduction of the suction loss become important to realize the more efficient scroll compressor. In this paper, the suction pressure pulsation of scroll compressor is analyzed by computational fluid dynamics (CFD) using finite volume method. The mesh shapes of suction path are defined by involute curves, which constituted scroll compressor. The 2 dimensional analysis program in which the depth of mesh is considered has been developed. The suction losses are analyzed numerically and compared to experimental results. The numerical results agree with experimental results with error of less than 10%. As application of analysis, the effect of inertia supercharging by the conduit added to suction of scroll was examined. With regard to the volumetric efficiency of compressor, the improvements of 1% in 60rps and 1.4% in 70rps are obtained by the effect of inertia supercharging experimentally, and the present numerical analysis is useful to predict those values.

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This study describes numerical approach for adhesion behavior of micro particle to a duct wall in gas solid two-phase turbulent flow in a horizontal duct. Flow field was simulated by low Reynolds number k ε turbulence model to estimate turbulence boundary layer accurately. The particle trajectories were simulated by means of Lagrangian method. The turbulence fluctuation component of fluid velocity was sampled randomly from the Gaussian probability density function based upon turbulence energy. The particle equation included wall-and shear-induced lift and rotary lift to estimate those effects to the particle adhesion behavior near wall region. It is assumed that the particle will stick to the surface when a particle once contacts to the wall. By the introduction of particle-wall collision model, the effect of particle collision angle on particle adhesion was considered. The simulation result for the particle deposition rate reasonably agrees with the experimental and simulation result of the other researchers.

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The anti-stall effects in two diffusers, a vaned diffuser with fixed small vanes and a low-solidity cascade diffuser, were compared in a centrifugal compressor with suction damper. These diffusers had the same outer diameter. The surge limit flow rate did not differ, however, the stability differed. To clarify the difference of stability, pressure measurement and numerical simulation were carried out. In the vaned diffuser, the flow guided by the small vane pushed back the flow from down stream of throat. This mechanism suggests instability near surge point. In the low-solidity cascade diffuser, there observed no backflow on the whole suction surface. This suggests the more stable character.

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Periodic flows downstream of centrifugal pump impeller in vaneless and vaned diffusers were measured by using a single hole yawmeter with a phase locked sampling method. The flows were also calculated by a inviscid flow analysis with the blade surface singularity method. The periodic variations in calculated static pressure with impeller rotating quantitatively agree well with measured ones. The flow behaviors in the vaned diffuser are discussed with measured and calculated results. The potential interaction between the impeller and diffuser blades appears more strongly than the impeller wake interaction. The appearance of static pressure fluctuations due to the impeller rotating in the fully vaned zone is different from that in the semi vaned zone of the diffuser. The existing of the peripheral surface of impeller outlet and the outlet edge of pressure surface of impeller blade causes the large pressure fluctuations in diffuser.

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A cavitation surge oscillation in the range of partial flow rate and low NPSH hinders the wide operation of an inducer for industrial turbo-pumps, though it is very effective to improve the cavitation performance. The harmful oscillation of cavitation surge occurs in the case of inducers with high solidity more than 1.0. This oscillation might be suppressed if a tandem bladed inducer, having a front inducer with low solidity less than 1.0, would be employed. Experiment tests to examine its effect are described in the present paper. Results show that the amplitude of the oscillation takes almost zero when a relative peripheral or axial position between the front and rear blades is properly chosen. The reasons are discussed with measured casing wall pressure distributions and observed cavitation behaviors.

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Pneumatic transportation for fragile materials and tablets is a big challenge in pharmaceutical industry. The horizontal pneumatic conveying of granules was experimentally performed in order to investigate the effect of spiral flow on the granule destruction. The spiral flow used is weak and the maximum circumferential velocity is about 2.2m/s and the maximum swirl number is 0.03 when the mean air velocity is 30m/s. It was found that the spiral flow is effective to reduce the damage at lower air velocity as the mass flow rate of granule is increased. A numerical simulation showed that the number of collision between granule and pipe wall in the spiral flow is larger than that in the rectilinear flow but the kinetic energy of granule that comes in collision with the pipe wall is smaller in the spiral flow than in the rectilinear flow. It is inferred that the spiral flow makes the granules move along the pipe wall to reduce the kinetic energy of granule below the threshold of granule strength for destruction.

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A basic study was conducted for a heat transport device utilizing a temperature-sensitive magnetic fluid whose magnetization largely depends on temperature. The device is rotated with its own axis in a magnetic field, and it is functioned by driving forces derived from the centrifugal force and the thermo-magnetic body force. In the present study, heat transport characteristics for the device were investigated numerically and experimentally. The flow and temperature states of the device was obtained by numerical analysis in order to examine the basic heat transport performance. It has been clearfied that heat transport characteristics largely depends on the flow states of the device when the magnetic field and rotation are effected.

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A study of direct-heat-to-power energy conversion device, using temperature-sensitive magnetic fluid, was conducted. Numerial simulation was carried out in order to obtain fundamental characteristics of the device. The working principle of the device is based on the thermo-magnetic effect of magnetic fluid, in which the driving force (the driving pressure) needed to circulate magnetic fluid in the thermodynamical power cycle can be derived from the magnetization difference in a temperature field. When a magnetic field is imposed on the rectangle box in which a magnetic fluid is enclosed, a magnetic fluid is made to circulate so that a rotation disc inside the rectangle box is rotated by the friction of the fluid flow. Magnetic fluid is modeled by Rosensweig equation and its magnetization is calculated with Langivin type equation. results of numerical analysis showed various aspects of the device, indicating that the device is feasible as thought by the theory (power generating thermo dynamical system). Optimization of the device is also considered to gain sufficient shaft output and the efficiecy. It is concluded that further development of the device is possible with different structure of the device as well as the direction of imposing magnetic field.

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We propose a new smart or intelligent fluid which reacts upon a magnetic field. It is a magnetic compound fluid (MCF). We measured the relation of shear stress to shear rate with a rotating rheometer as its hydrodynamic characteristics and the complex magnetic permeability at heigh frequency range as its magnetic characteristics. The hydrodynamic characteristics can be varied qualitatively and quantitatively by the direction of the applying magnetic field, the type of a rotating body in the rheometer and the compound rate of the iron and the magnetite particles. The magnetic characteristics can be varied by the the compound rate of the iron and the magnetite particles. Also, the MCF is expectable for engineering applications with using a magnetic field.

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As a model for an artificial heart valve, two dimensional unsteady flows around a passively rotating plate were analyzed numerically. In this study, the equation for mass conservation, the equations for momentum conservation and the equation of plate for rotational motion were used to calculate the flow fields around the plate. Moreover, the ALE method was adopted to analyze the moving boundary problem. The numerical results were summarized as follows : (1) Within the present calculation, the overshoot angle of plate was less than 5×(10)^-4 radian. (2) The passive rotation of plate had an effect of decreasing the shear rate around the plate.

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A rapid expansion of moist air or steam through supersonic nozzle often leads to nonequilibrium condensation shock. Depending on the heat amount released by condensation of water vapour, the flow is highly subject to a periodic oscillation of condensation shock in the nozzle. The unsteadiness of the condensation shock is always associated with several kinds of instabilities as well as noise and vibration of the flow system. In this paper, a passive technique using a porous wall with a plenum cavity underneath is applied for the purpose of alleviation of the condensation shock oscillations in a supersonic nozzle. A droplet growth equation was incorporated into two-dimensional Navier Stokes equation systems. Computations are carried out using a 3rd-order MUSCL type TVD finite difference scheme with a 2nd-order fractional time step. As a result, the oscillations of the condensation shock wave are completely suppressed by the present passive control method.

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The effects of stable and unstable thermal stratifications on both scalar transfer across the wind driven air water interface and turbulence structure were investigated through laboratory experiments in a wind-wave tank. The steady stable and unstable thermal stratifications were generated in the wind wave tank by supplying cold and hot waters into the upper and lower parts of the tank. Instantaneous streamwise and vertical velocities and temperature in the water flow were simultaneously measured using a laser Doppler velocimeter (LDV) and a cold film I-probe operated by a constant-current temperature bridge. The results show that the turbulence quantities in the stratified layer are strongly affected by buoyancy. However, the turbulence quantities just beneath the air water interface and the frequency of the appearance of large-scale surface-renewal eddies that dominate heat and mass transfer across the air-water interface were not affected by the stable and unstable thermal stratifications. The facts suggest that the stable and unstable stratifications in the interfacial water flow do not play an important role in the heat and mass transfer across the wind driven air water interface.

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By-pass transition of the Blasius boundary layer is directly simulated on a parallel computer. Navier-Stokes equation is solved by the Fourier-Chebyshev spectral method and the simulation starts with an initial flow given by the basic flow plus small disturbances. An a result, it is found that for any initial disturbances, transient growth of streamwise vortices is induced by the linear instability in the flow. Then, only for the disturbance with an amplitude larger than the threshold value, the induced streamwise vortices are amplified further by the nonlinear instability to them with strong three-dimensional deformation. Ultimately, the nonlinear instability breaks down the flow to turbulence. The nonlinear amplification of the streamwise vortices is a distinctive feature of the bypass transition in comparison with the transition induced by the Tollmien-Schlichting wave instability. The threshold amplitude of the initial disturbance, which triggers the transition, depends on the Reynolds number, Re, and its functional form can be described as Re^-γ. We estimate the numerical value of γ as 1.7, which is equal to the value obtained in the channel flow.

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The effect of irrotational strain on stably stratified turbulence is investigated using the rapid distortion theory (RDT) which has been newly developed for a variable density gradient. We consider two kinds of strain which correspond to the longitudinally and laterally distorting ducts. We found that the most important parameter is the ratio of the initial Brunt Vailsala frequency to the strain rate. However, time development of the energies and the fluxes have shown that the oscillation period is approximately π/N independent of the strain, showing the dominant role of stratification. Comparison of the RDT results with the experiments also gives good agreement. For example, the strain prevents the decay of vertical kinetic energy, and the vertical buoyancy flux becomes more downgradient. These results show that many of the characteristics of the stratified turbulence with irrotational strain can be explained qualitatively by the linear processes described by RDT.

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Two different subgrid-scale scalar flux models, namely isotropic and anistropic representation, for the dynamic procedure using finite difference method are derived following the procedure proposed in the previous reports. The proposed models have been assessed on plane turbulent channel flow with passive scalar transport at various grid resolutions and are found to show better agreement with DNS results than those of Smagorinsky's model. The isotropic model is improved to be anisotropic representation by considering the effect of GS velocity gradient on the SGS scalar flux and using the results of a priori test obtained by the LES of a finer grid resolution. The anisotropic model mitigates the isotropic one's overestimation of scalar intensity and streamwise scalar flux near the wall. The notable feature of the proposed models is their insensitivity to the discrete form of the test filtering operation applied during the implementation of the dynamic procedure, which clearly indicates the validity of the proposed models for use in the context of finite difference method.

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The axial velocity, radial velocity and concentration of a high Schmidt number matter were measured simultaneously in an axisymmetric turbulent jet. The diffusing fluid is a water solution of the commercial dye (Schmidt number Sc≃3800), and an issuing Reynolds number is 6400. A combined probe of a fiber optic concentration sensor and a X type hot film was used to measure the axial velocity, radial velocity and concentration simultaneously. Joint pdfs of concentration and radial velocity have symmetries in whole scales on the jet centerline. Correlation vanishing scales of the concentration and radial velocity are smaller than those of the concentration and axial velocity at the region off the jet centerline.

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Deformation of a liquid drop fallen on the stationary silicone-oil surface was examined in detail. Special attention was directed to the influence of the liquid-drop and silicone-oil properties on the deformation of the drop after the impact with the oil surface. Water solutions of ethanol or glycerin with various concentrations were used for liquid drop to control its surface tension σ_L and kinematic viscosity ν_L. Various kinds of silicone oils were tested that cover a wide range of kinematic viscosity ν_T, 1&acd;(10)⁵(mm)²/s, under nearly a constant surface tension. The drop diameter at its maximum spread, d_M. is influenced by not only σ_L and ν_L of the drop itself but also ν_T of the silicone oil. The influence of σ_L on d_M is pronounced under the condition of ν_T<(10)²(mm)²/s, whereas ν_L has a significant influence on d_M over the whole range of ν_T. With highly viscous silicone oil of ν_T>(10)⁴(mm)²/s, d_M/d_L (d_L : initial diameter of drop) for all σ_L and ν_L can be well correlated by Reynolds number and Ohnesorge number.

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The present aim is to clarify the streamwise thickness effect of a ring with rectangular cross sections, which is immersed perpendicularly to uniform flow. In a wind tunnel, we carried out measurements using a pressure transducer and a hot wire anemometer, and flow visualisations by a somke wire method, for Re=5.0×(10)³-1.5×(10)⁴, d/ω-4.0-8.0, and t/ω=0.29-1.30, where d. ω and t are mean diameter, cross section width and cross section thickness of the ring, respectively. Consequently, Strouhal number St, which is a reduced frequency of regular vortex shedding from the ring, is independent of t/ω, d/ω and Re. On the other hand, we can observe the maximum base suction and the maximum drag at a certain critical value of t/ω, depending on d/ω. We can clearly classify flow into two modes, viz., sub and over critical modes. Round the critical is a transition range of the modal shift. Over critical leeward extension of the after body drastically enhances the formation of vortex rings, and weakens a ring curvature effect. Only the existence of an inner sidewall is essential for the modal shift.

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A helical screw expander, is a rotary positive displacement machine, is expected to adapt a small sized energy conversion machine from the waste heat or a total flow expander for the geothermal resources. So far, fundamental performance of the helical screw expander had been studied experimentalluy. But, more detail data with wide operating conditions are need to estimate the performance of the helical screw expander. In this work, we developed the simulation program, which included leakage losses and dynamic losses of the flow past through the inlet or the discharge port. Furthermore, the unsymmetrical rotor profile, which had been used in the experimental studies, is used in this performance analysis method. Simulation results are agreed with the experimental results, especially at the low speed region. Then this simulation method is applicable to evaluate the performance of a helical screw expander.

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This paper describes a numerical prediction method for hemolysis properties in orifice-pipe blood flows. In this study, several types of orifice pipe flows by using two turbulence models are computed, which are (1) standard low Reynolds number k ε model and (2) the k-ε model with partly patched Launder-Kato model (LK Zonal model) to improve computational accuracy. These predicted flows are compared with (a) measuring pressure loss and (b) measuring reattachment length, and it is found that the flow using LK-Zonal model has good agreement with experiments. Then the hemolysis properties are estimated from the predicted flows. The results are 1) computational accuracy of orifice pipe flow is improved by using LK-Zonal model, 2) accuracy of predicted hemolysis is also improved especially in orifice-pipe that have long contracted part.

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A monopivot centrifugal blood pump, whose impeller is supported with a pivot bearing and a passive magnetic bearing, is under development for implantable artificial heart. The hemolysis level is less than that of commercial centrifugal pumps and the pump size is as small as 160mL in volume. To solve a problem of thrombus caused by fluid dynamics, flow visualization experiments and animal experiments have been undertaken. For flow visualization a 3 times scale up model, high speed video system, and particle tracking velocimetry software were used. To verify nonthrombogenicity 1 week animal experiments were conducted with sheep. The initially observed thrombus around the pivot was removed through unifying the separate washout holes to a small centered hole to induce high shear around the pivot. It was found that the thrombus contours corresponded to shear rate of 300s^-1 for red thrombus and 1300&acd;1700s^-1 for white thrombus, respectively. Thus flow visualization technique was found to be a useful tool to predict thrombus location.

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Relatively high cost is the highest barrier for developing micro-hydropower. A cross-flow turbine is suitable for micro-hydropower because of its simple structure. In this study, in order to further simplify the structure, a guide vane is removed, and the runner chamber is made compact using a new air supply method proposed by the authors. As a result, the size of the turbine is remarkably reduced, and in the meanwhile the efficiency of the turbine is improved by about 2% in a wide operating range.

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This paper reports a multiple time-scale turbulence model for a thermal field in shear flows. The model is based on the concept of the three divided thermal fluctuation spectra. The spectrum in the highest wavenumber region is modeled using an algebraic relation concerned with the molecular Prandtl number, and the remaining two other regions are modeled with four differential equations. Comparisons with the DNS data indicate that the present model works well for the predictions of thermal fields not only in wall shear flows under varions Prandtl numbers but in homogeneous shear flows with a mean thermal gradient.

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This paper describes a method for obtaining an excellent spray under low injection pressure. Since the diesel nozzle, which is used in direct injection diesel engines, is a pressure atomized type nozzle, excellent spray characteristics can not be obtained under low injection pressure. When cavitation occurs in the nozzle hole, atomization of the liquid jet enhanced considerably. Based on the results of a previous study, a new method of enhancing atomization of the liquid jet at low injection pressure, which involves the use of a simple nozzle in which a gap made at the nozzle hole, is proposed. The spray characteristics of the nozzle invented in this study were compared with those at super high injection pressure (ΔP_i=200MPa). The results of the present study indicated that enhancement of atomization of the liquid jet at low injection pressure (ΔP_i=10MPa) is possible by simply making the gap and installing the bypass at a single hole nozzle.

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A numerical model to analyze the internal conditions of a MCFC stack has been modified to estimate single electrode heating value. Magnitude of heat that evolves on the cathode and reabsorbed on the anode has similar order to an electrical output from MCFC. A temperature distribution in the electrolyte plate has been studied applying thermodynamics of irreversible process. Calculated temperature distribution has been compared with the temperature distribution without single electrode heat effect. Calculated absolute value of Thomson coefficient in the MCFC electrolyte plate has been evaluated to be lower than 0.1mV/K. Finally, temperature differences between cathode and anode have been estimated for the different thermal conductivity of electrolyte plate. The temperature difference between two electrodes are calculated to be small value under the normal operating condition of MCFC.

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First. a wake with positive buoyancy from a circular cylinder is formulated as a three dimensional and time dependent behavior of compressible fluid flow. Next, numerical methodology for the wake is obtained by employing the grid generation by solving the elliptic partial differential equations and by extending the HSMAC method to compressible fluid flow. As a result, in an isothermal wake, the above formulation and methodology becomes those for an incompressible fluid flow. The Strouhal numbers, time averaged drag coefficients, rms amplitudes of the lift coefficient, distribution of the vorticity with the cylinder axis direction, and streaklines obtained by the present computation at the Reynolds numbers 100 and 300 agree well with the previous studies. Furthermore, the time averaged mean Nusselt numbers obtained by the present computation at the Grashof numbers 0 and 490 and the Reynolds number 70 agree well with the previous studies. The present formulation and methodology are therefore validated.

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In this paper the characteristics of evaporating fuel sprays injected into a high pressure and temperature cylindrical vessel are investigated by means of an electronically controlled common rail injection system. A laser induced fluorescence method was used to separate vapor and liquid phases of the spray. Two methods were conducted to investigate the qualitative and quantitative applicability of the technique in a high pressure and temperature atmosphere during the fuel injection period. Firstly, we calibrated the relationship between fluorescence intensity and vapor concentration of dopants at different temperatures. Secondly, we calculated the spray evaporation processes using the KIVA 3 code, which is commonly used in engine combustion simulations. Then, the distributions of fuel vapor concentration in diesel sprays were analyzed.

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The formation of dioxins in municipal solid waste incineration processes has been investigated using a laboratory-scale fluidized-bed incinerator. As the dioxins formation is influenced by many factors, in particular combustion characteristics such as air ratio, temperature, and residence time, the laboratory-scale fluidized-bed incinerator was conducted such that each factor could be varied independently. In the experiment, artificial refuse-derived fuels were used to ensure experimental accuracy. To elucidate the conditions of the dioxin formation in a municipal solid waste incinerator, a theoretical analysis was also conducted on the basis of chemical equilibrium. From the chemical equilibrium considerations and the experimental results, we conclude that the formation of dioxins in municipal solid waste incinerators occurs as a result of the heterogeneity of components in the combustion field.

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In order to elucidate the enhancement mechanisms of turbulent flame propagation, it is indispensable to examine and clarify the detailed process of vortex-flame interaction. This is because that the vortex-flame interaction constitutes one of the key processes to promote flame propagation velocity. In this investigation a spark ignited flame is optically observed and examined, which is initiated and propagating in the coherent structure in the plane premixed shear flows. In this paper, as the first step, characteristics of coherent structure without combustion, such as the eddy spacing and diameter are actively controlled using acoustic excitation. Varying the setting conditions of the plane shear flow also varies the convection and tangential velocities. It is found that the acoustic excitation enables the formation of coherent structure having a relatively wide range of properties in the plane shear flows, indicating the possibility to realize the vortex flame interaction under the practical and complicated combustion conditions.

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The flame temperature of a laminar premixed flame with continuous convex and concave curvatures was experimentally investigated. The flame temperature and the stretch rate along the flame surface were measured for the flame formed in the lean propane/air mixture (φ=0.72, Le=1.74). As a result, the flame temperature at the convex toward the unburned mixture was lower than the adiabatic flame temperature and that of the concave was higher, because of the flame stretch and the Lewis number effect. However, the measured flame temperature was different from the estimated flame temperature by the theory for the local flame structure proposed by C. J. Sun et al. We guess the reason why such difference was arisen is the existence of the heat transfer along the flame surface, so we suggest that the heat transfer along the flame surface should be considered in the case of the flame with continuous convex and concave curvatures.

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To estimate the noise emitted by a industrial tube burners (immersion tube burner and radiant tube burner), simulated and experimental analyses are carried out. Firstly, combustion noise is measured and the overall characteristic of noise is examined. Secondly, one-dimensional noise analysis programmed with a transfer matrix method is used. A lot of efforts have been made to analyze the noise from home use combustion device considering the temperature distribution inside the tube. In this study, the distribution of heat generation rate is taken into account to obtain sufficient accuracy for the noise at the exhaust tube outlet, in addition to the conventional temperature distribution. The distribution of heat generation rate is numerically analyzed considering the heat transfer at the inner and outer surface and the radiation at the outer surface of combustion tube. As a result, the theoretical results show relatively good agreement with the experimental results and the analytical method employed in this study has been confirmed to be practical for noise analysis of industrial tube burners.

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In recent years, concern has been raised about developing a distributed energy system and the micro gas turbine and the fuel cell are used for it. Solid oxide fuel cell (SOFC) has a high electric generation efficiency and a high operating temperature (about 1000°C). It is easy to combine a gas turbine with the SOFC because the SOFC operating temperature matches the turbine inlet temperature (TIT). In this study, we proposed the multi stage type SOFC/GT combined system and compared the system performance of it with that of other traditional combined systems using the thermal efficiency and exergy evaluation. It is noted that the thermal efficiency of the 3-stage type SOFC/GT combined system can be reached more than 70% (HHV) at low pressure ratio.

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The improvement of fuel economy in passenger cars and trucks contributes directly to CO₂ emission reduction. Recently, low fuel consumption cars are developed, however most of operated cars are still old types. To estimate the effect of new engine systems, light weight cars and running conditions on fuel economy, in this study a new calculation method of fuel consumption was proposed. In this calculation even if the engine types and sizes were changed, the fuel consumption is easily calculated from the indicated thermal efficiency and friction mean effective pressure. Here by applying the running mode in the center of local city the total fuel economy included small passenger cars to heavy duty trucks was estimated. As the result, the influence of new type engine, light weight cars and driving patterns on fuel economy was made clear.

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