In order to examine the reliability of computational results, two-dimensional flow fields around a circular cylinder were analyzed in the Reynolds number range from 10² to 3×10⁵, using the third-order upwind finite-difference method (k-k scheme). The drag coefficient and Strouhal number were compared with experimental results. For low Reynolds numbers, numerical results showed good agreement with experiments. To evaluate the effect of numerical viscosity, all terms of the Navier-Stokes equation were numerically compared with each other. It was found that at high Reynolds numbers, the convergency of the numerical results was insufficient, and the numerical viscosity in the k-k scheme was much higher than actual viscosity.

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Numerical simulations of a reacting 2-D plane shear layer are performed using the fast mixing model which we proposed in a prior paper. Shear flow is simulated by a Lagrangian particle tracing method with a stochastic model based on turbulent statistical quantities. The chemical process used here is "A+B→P", ignoring heat release. The validity of this model has been investigated for the following cases : 1) effect of reaction rate, 2) effect of lean-to-rich reactant ratio, 3) effect of "flip" case, in which chemical species of the high-speed side and the low-speed side are exchanged. This study proves the capability of the fast mixing model for simulating reacting shear flows.

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By making use of the techniques of molecular dynamics simulation and Langevin simulation, we study one-dimensional interfaces which separate two distinct fluids. In particular, we address the potential capabilities of the two techniques for simulating the canonical ensemble averages of one-dimensional interfaces. In the molecular dynamics simulations, a microcanonical ensemble average is simulated by introducing the canonical momentums of the molecules which make up the interface. In the Langevin simulations, we solve a discretized Langevin equation of the molecules, which are considered to be Brownian particles, by a Euler algorithm. We find that the two techniques and the Monte Carlo give the same results for internal energy and specific heat, and that there are systematic discrepancies between the molecular dynamics and the MC for the average square size and fractal dimensions. Our conclusion is that the Langevin technique can successfully simulate the canonical ensemble average of one-dimensional interfaces ; however, the molecular dynamics in this study cannot. We also examine a hybrid technique of molecular dynamics and Langevin simulations, and find that it yields the same results that the MC and Langevin simulations yield.

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Existence of a critical opening angle θ_c was found in steady experiments on an angled annular impinging jet. This paper deals with unsteady characteristics of the flow field. The cross-spectrum and correlation functions of pressure fluctuation at the center of a disk placed at the downstream end of an inner tube and on flat plate bombarded by the jet were measured simultaneously by varying the distance H between the angled annular nozzle and the flat plate. It was found that there were four types of large-scale distinguishable frequencies for pressure, accordig to the value of H in the case of opening angle θ<θ_c, but only one type in the case of θ>θ_c. It was verified that large-scale fluctuation existing in the flow field of the angled annular impinging jet had essentially two modes in the case of θ<θ_c and one mode in the case of θ>θ_c.

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It has been shown that the premixed abrasive water jet system, in which an abrasive suspension jet is formed by propelling a premixed abrasive suspension through a nozzle, has a greater capacity for drilling and cutting than the conventional abrasive water jet system. In the present investigation, an apparatus of the premixed abrasive water jet system was constructed for experimental purposes, and the erosion characteristics under submerged conditions were studied. The maximum jetting pressure was 20 MPa. The pressure in the test cell was varied up to 1 MPa. The erosion tests with the cavitating water jet and the submerged abrasive jet were conducted. It is found that the mass loss and the erosion pit depth when using the submerged abrasive jet decrease with increasing stand-off distance and pressure in the test cell. The erosion characteristics due to the submerged abrasive jet is affected greatly by the cavitation phenomenon.

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The fluid oscillation phenomenon, oscillating phenomenon of a jet in a jet-edge system and that at the interface of an open cavity, are studied using computational fluid dynamics. Results are compared with experiments and discussed. Preventive measures for interface oscillation at the opening of a vehicle are developed to reduce noise level using the present method as a computational flow visualization technique.

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Control of turbulent jets has applications in the manufacturing industry. It has been reported that it is possible to control the jet structure by a pure tone. However, in pure-tone-excited jets, the detailed characteristics of the flow fields are unknown. In this paper, a jet excited by a pure tone radiated from the direction perpendicular to the axis is addressed. A woofer was set downstream near the nozzle. As a result, we found that the cross section of the jet was distorted elliptically in shape. It was clarified that the distorted cross section depended on frequency and sound pressure level of the excitation. This phenomenon is very useful to control jet flows, since it can change the characteristics of the flows. We attempted to clarify the mechanism of elliptical distortion of the jet cross section, assuming the mixing region of the jet was organized into many vortex rings in a time-averaged domain.

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A numerical simulation is performed on dispersed gas-solid flow in a vertical channel. Flow of the solid phase is determined by calculating individual particle motion, i. e. by the Lagrangian method, while the gas flow is determined by solving the equations of inviscid fluid. The Direct Simulation Monte Carlo (DSMC) metod is used to take account of particle-to-particle collisions. Attention is paid to the case of low gas velocities and high solid loading, for which the solid phase strongly affects the gas flow field. The flow fields of gas and solid are accordingly solved simultaneously, taking the interaction between both phases into consideration. It is found that the flow becomes unstable and inhomogeneous as the gas velocity decreases and the solid loading increases. Further-more effects of parameters such as the channel width and physical properties of particles on the instability and cluster formation are investigated.

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The multidimensional residual averaging technique using the block iterative method has been applied for the two-dimensional Euler equations. The governing equations are spatially discretized using a central difference approximation and subsequent time integration using the rational Runge-Kutta (RRK) scheme. The implicit residual averaging (IRA) technique in multidimensional form has been applied for the purpose of accelerating convergence to a steady state. As a numerical scheme for the Poisson-like equation resulting from residual averaging, the block iterative method, also known as block successive over-relaxation, has been adopted. This method leads to a reduction in the number of steps required to reach the steady state in comparison with the technique of conventional residual averaging with approximate factorization (AF). It has also been shown that the present method can be combined with a block checkerboard iterative technique, which is suitable for a vector computer.

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The effect of compressibility on the growth of instability modes in a plane free shear flow was studied in this work. The linear disturbance equations of compressible plane free shear layers are solved using a direct spectral method. The mapped spectral method (mapped Fourier method) for the free shear flow of the unbounded boundary conditions was employed. The eigenfunctions satisfy the homogeneous Dirichlet boundary conditions at infinity. Numerical results reveal that oblique modes (3-D modes) are significant in the mixing layer as the convective Mach number M_c increases. Above M_c=0.6, the most unstable mode and also its two subharmonic modes are oblique waves. The fundamental and subharmonic eigenfunctions at M_c=0.8 are presented in this paper. The eigenfunctions structures are affected by the convective Mach number.

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A number of accurate constitutive equations are required for reliable prediction of multidimensional two-phase flow. However, few constitutive equations have been established due to the lack of (1) simple numerical methods for solving governing equations of multidimensional two-phase flow and (2) reliable experimental data on multidimensional two-phase flow. In the present study, a simple and efficient numerical method for solving a multidimensional incompressible two-fluid model, which is based on the simplified marker and cell (SMAC) method, was proposed to facilitate the development of constitutive equations. This method enables us to calculate multidimensional two-phase transient phenomena with a personal computer. Details of the present method and a comparison of measured and predicted two-dimensional flow patterns of two-dimensional bubbly flow are described.

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The aim of the present study is to show that a sudden transition from laminar to turbulent flow due to nonuniformity of vorticity occurs in a radial free liquid-film flow having a axisymmetrically twisted velocity distribution. In the first report, the velocity distribution of the laminar flow is described. This flow was generated by releasing a thin liquid film on the upper surface of a rotating disk into the atmosphere. The velocity distribution in the flow was measured using a laser Doppler velocimeter. In a theoretical treatment, a similarity-type transformation in conjunction with a stream function was applied to appropriate nonsimilar boundary-layer equations. The final theoretical equations were solved numerically by means of the finite difference method. The experimental data were in good agreement with the calculated results, showing that a three-dimensional boundary-layer-type velocity profile at the end of the rotating disk gradually becomes uniform in the down-stream direction.

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The transition from laminar to turbulent flow in a radial free liquid-film flow having three-dimensional velocity distributions is investigated experimentally. The flow was generated by releasing a thin liquid-film flow along a rotating disk into the atmosphere. The features of the liquid surface in the transition region were carefully observed using a stroboscope, and the velocity distribution in this region was measured by LDV. In the transition region, it was observed that new disturbance waves grew rapidly in the downstream direction, which were different in quality from that in the flow along the rotating disk. It was also found that weak three-dimensionality of the flow suppressed transition, whereas strong three-dimensionality promoted it. The results from the LDV measurement showed that the radial velocity component rapidly decreased to become uniform, owing to the transition.

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The artificial turbulent spots in Blasius boundary layer developed on low pressure wall, in which Coriolis force affects normal to the wall, have been investigated. The turbulent spots are initiated by the jet disturbance through a small hole on the test surface. The probability of the spot generation with constant disturbance intensity shows that Coriolis force stabilization reduces the generation of the turbulent spot, agreeing with the previous result of the natural transition related to the Emmons theory. The ensemble-averaged measurement of the velocity field of the turbulent spot shows that that the turbulent intensity near the wall is dumped and that the spanwise growth is inhibited by Coriolis force.

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Turbulent flows in a rotating channel are studied numerically using the k-ε model based on a statistically derived generalized eddy-viscosity representation. In this model, the effect of rotation is taken into account through the Reynolds stress and the energy dissipation rate (ε) equation. Various computed turbulence quantities are compared with experimental data and previous numerical results. The comparison shows that the present generalized k-ε model gives reasonable results for the major characteristic properties of the rotation channel flow.

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Second-order closure models are now in wide use for various applications. The recent develop-ment of the DNS data base has brought about further improvements in the second-order closure models. In the present research, a new second-order closure model is proposed, in which functional forms of model coefficients in the rapid part of the pressure strain are determined to ensure consistency with the rapid distortion theory and the realizability principle. It is shown that the new model yields good agreement with the existing DNS and experimental data for homogeneous turbulent flows. Significant improvements are obtained by the new model compared to the existing models.

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Bursting occurs randomly in space and time, but has identifiable scales. In the light of this fact, an external acoustic perturbation, the time and length scales of which were the same as those of the bursting were applied to the Couette flow formed between concentric annuli. By LDV measurements, turbulence response to external perturbation has been investigated, and marked turbulence amplification has been observed at the frequencies proportional to the Reynolds numbers. The pertubation which caused such resonance behavior was termed "specific external regulation".

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Under the condition where turbulence is maximally amplified by the external perturbation, the time-averaged and phase-averaged flow characteristics have been investigated in detail. It has been shown that both the ejection-type and sweep-type motions occur simultaneously when the perturbation from the slits corresponds to blowing. The phase-averaged turbulent intensity demonstrates that there exists a relatively calm period as well as a relatively violent period during one cycle of vortex development excited by "specific external regulation" (SER). This fact indicates that bursting is fixed in space and phase-locked by the SER.

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In order to investigate the effect of gap size on the centerline development of a boundary layer flow through a gap in an isolated wall-mounted roughness element, the turbulence quantities for flow through four gap sizes have been measured. All measurements were made at a Reynolds number of 3300, based on obstacle height and free stream velocity. From the centerline features immediately downstream from the gap, the gap size can be classified into three cases, the S gap (G/δ₀=1/8), M gap (G/δ₀=1/4 and 1/2) and L gap (G/δ₀=1). The magnitude of each turbulent quantity due to the distortion produced by the gap varies with gap size. However, the turbulent quantities show similar downstream tendencies independent of gap size. The turbulent properties show maximum distortions at x/G=4 to 10 downstream from the gap. The gap size effect on major flow features was also analyzed with both the appropriate velocity and length scales. Further downstream from the gap, it is shown that all four centerline turbulent flows are different from undisturbed flow.

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The mechanism of the pressure rise in a gas-liquid two-phase pipe flow of magnetic fluid in a nonuniform magnetic field is investigated in detail both theoretically and experimentally. Firstly, governing equations of one-dimensional gas-liquid two-phase magnetic fluid flow are presented and numerically solved. Next, the pressure distribution in a nonuniform magnetic field region is measured in the cases of two-phase flow, single-phase flow and the stationary state using a new experimental apparatus for the flow system. From the numerical and measurement results, the magnitude of the pressure components which contribute to the total driving force is accurately estimated. These results on the pressure distribution will contribute to the development of a new energy conversion system using gas-liquid two-phase magnetic fluid flows.

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Ventilation by high-frequency oscillation (HFO) has gained widespread attention in clinical medicine because of its potential benefits to respiratory insufficiency. The axial dispersion in oscillatory flow is one of the important factors influencing gas transport during HFO. In this study, the gas transport in sinusoidally oscillatory and intermittent laminar flow in a straight circular pipe was numerically simulated to reveal the mechanism of dispersion. The diffusion of substance was simulated according to the random walk technique and its diffusive nature was evaluated by tracking the path of marked particles. The presence of a stationary period enhances the axial gas transport in the oscillatory flow, and the maximum ratio of effective diffusivity to the molecular diffusivity is twice that of sinusoidal oscillatory flow.

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The key considerations of the design of the active attenuator for wide-band random pressure pulsation, in which the transfer-function-based control method is used, may be said to be the following : (1) obtaining a satisfactory attenuation performance by matching a transfer function of the controller (specifically, the signal processor) with the desired (target) characteristics as precisely as possible and (2) preventing howling by increasing the degree of stability. This paper presents an analysis of a stability problem of our newly designed active attenuation system, which was carried out from the viewpoint of the above-described objective (2), in succession to the previous paper studied from the viewpoint of objective (1), together with considerations of the stability of Lueg's system. It has been confirmed by both theoretical analysis and tests carried out on the small-sized model experimental pipeline that the present active attenuation system, which detects the progressive wave propagating in the downstream direction alone and then controls the single second source using this signal, gives a far better degree of stability than that of Lueg's system. Furthermore, the tolerance of error in setting up the characteristics of the controller, such that the stable operation can be achieved while maintainning a satisfactory attenuation (around -20 dB) for almost all harmonics of the wide-band random pulsation including harmonics of 15 to 400 Hz, also been clarified.

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Performance of through-vane compressors used for automotive air conditioners is affected greatly by frictional loss on vane tips, and the magnitude of the frictional loss changes with lubricating condition. To estimate the frictional loss on the vane tip, we need knowledge on the relationship between the lubricating condition and the coefficient of friction under a given geometry of the vane tip and surface roughness. In this study, we measured the coefficient of friction experimentally, using a compressor model, and investigated the influence of the vane-tip radius and the surface roughness on the lubricating condition. It is found that when the oil film thickness becomes less than three times the surface roughness, the lubricating condition changes from hydrodynamic to mixed lubrication. Theoretical calculation reveals that the coefficient of friction on the vane tip changes with rotational angle of the compressor and that the frictional loss in the through-vane compressor is greatly influenced by the radius and the surface roughness of the vane tip.

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The propagation of acoustic waves from a variable-area duct, such as a throat duct, in the presence of a steady subsonic inlet flow has been studied. The acoustic equations are derived by perturbing the unsteady Euler equations about the steady mean-flow state and are formulated in generalized curvilinear coordinates. These are solved numerically by using a MacCormack-type scheme with spatial fourth-order accuracy to obtain the multidimensional structures of the sound fields. The present results show that the directivity of the sound pressure level at the far field is influenced by the duct geometry and that the nonuniform throat flow reduces the acoustic energy.

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The helium-air exchange flow through a small vertical opening with a partition was experimentally investigated. The vertical partition was aligned with the center line of the small opening to evaluate the effects of the multiple openings. The dimensionless exchange flow rates, i.e., Froude numbers, were experimentally obtained with several opening ratios (H₁/D_f), i.e., the ratio of the height to the effective diameter of the opening. In the case of low opening ratios (H₁/D_f<0.75), the measured Froude number for the multiple openings were almost the same as that for the single opening. The Froude numbers could be predicted with Epstein's modeling for a single opening. In the case of high opening ratios (H₁/D_f &ge;0.75), the measured Froude numbers for the multiple openings were larger than those for the single opening, because the upward and downward flows were separated by the vertical partition. Based on the balance between the pressure losses in the openings and the driving force due to density difference, the exchange flow rate was calculated, and found to agree qualitatively with the measured Froude numbers. The effect of the upward and downward flow interaction at the exit of the opening was found to play an important role in the prediction of the Froude number.

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A highly-sensitive technique for gas pressure measurement has been developed using laser-induced plasma fluorescence. ArF laser light of 193nm is focused into CF₃I/Aγ gas mixture, where Ar is ionized by the 3-photon absorption. A highly pressure-dependent fluorescence intensity is obtained which originates from the 3-body reaction of Aγ⁺₂, Aγ₂ and Aγ₂ with two Ar atoms. Pressure fluctuation in a turbulent jet is measured applying the present method. Pressure fluctuation beyond the instrumental noise level can be measured, where the instrumental noise level is 0.5 percent of the total pressure.

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Aerodynamic characteristics of oscillating cascades of blades accompanied with elastic deformation of blade sections in a uniform incompressible flow are predicted numerically. Unsteady formulation is based on a small perturbation approach with use of potential equations expressed on a moving computational grid. The governing equations are discretized by the finite element method. Modal shapes of blade oscillation are obtained first and a parametric study on unsteady aerodynamic characteristics is conducted for the two-dimensional cascade of the tip section of a test compressor. Furthermore, the oscillation displacement of the blades is divided into four components, i.e., two translational components (normal and tangential to the blade chord), a rotational component, and a section-deformation component, in order to analyze the contribution of each component to unsteady aerodynamic work which causes flutter excitation. It is shown that the effect of the blade section deformation is very significant in determining the unsteady characteristics of oscillating cascades.

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According to the classical unsteady airfoil theory, unsteady forces of an airfoil with steady loading consist of four terms : the quasi-steady term, the wake effect term, the apparent mass term and the term due to the interaction of steady vortices and unsteady velocities. In the present paper, unsteady airfoil theory is applied to a whirling centrifugal impeller. Its geometrical shape is simplified in order to neglect the effects of adjacent blades and to use the linear boundary conditions. The components of unsteady forces parallel and normal to the eccentricity F_γ, F_θ can be derived from the above-mentioned terms in a very simple way. From these results, the physical meaning of the whirling forces is easy to understand. This is a typical example to show the availability of analytical solutions.

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This paper deals with the effects of the diffuser radius ratio and diffuser width ratio on rotating stall in parallel walled vaneless diffusers. Equations for predicting initiation flow rate and rotational speed of cells presented in previous studies are examined using experimental data. The ratio of the radial length to the width of a diffuser affects the occurrence of rotating stall. Weak rotating stall occurs when this ratio is small. The reasons for this are discussed based on the results of previous studies. Predicted values of the rotational speed of cells agree well with measured values for the diffuser with a relatively large radius ratio. However, a small correction is required in the case of a small radius ratio.

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It is expected that a multiple-disk laminar flow fan has a very low noise level since it has no blade. But, in general, this fan has low efficiency in utilizing shear force. This paper presents a quasi three-dimensional flow analysis for the improvement of performance of a laminar flow fan. For the flow in the meridional plane, a nonviscous flow analysis using the streamline curvature method is utilized. On the other hand, the flow between parallel disks is analyzed by means of the angular momentum theory utilizing an expression for the local friction factor. The two kinds of calculations are successively repeated until the solution converges. Hence, the quasi three-dimensional flow in the laminar flow fan is analyzed. Moreover, the effects of flow rate and axial inclination angle of disk inner diameter on the flow are investigated.

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The transportation characteristics of a 45°-bend jet pump, which has a 45° bend connected directly to a water jet nozzle from outside of the bend, are discussed theoretically and experimentally. The transportation characteristics, which are predicted theoretically using the continuity, momentum and energy equations, agree well with the experimental results in the case of transporting water and solid spheres. When cavitation bubbles occur in the jet nozzle, the transportation characteristics, which are predicted theoretically considering a holdup of gas-liquid mixed fluid, agree well with the experimental results. The efficiency of the jet pump becomes higher as both the area ratio of the jet nozzle to the transporting pipe and the discharge ratio of solid spheres to water flow become larger.

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A new type of cyclone dust collector, which has an internal perforated cylindrical tube, has been developed. The internal perforated tube works to remove the inner forced vortex which appears inside a conventional cyclone dust collector and causes the pressure loss of the dust collector. The void fraction of the perforated tube is taken to be 20∼50%. Then, the dust collection efficiency was improved to 1∼3% and the pressure loss was decreased by about 40% compared with the conventional cyclone dust collector.

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Oxygen transport to a vessel of an aortic arch was numerically analyzed using the finite volume method. Oxygen delivery to the vessel is achieved through two pathways ; one is direct transport from blood flow in the lumen and the other is via the vaso vasorum. The oxygen transport from blood to the vessel consists of several processes ; release from hemoglobin, convection to the vessel wall, simple diffusion, and metabolism in the vessel. The blood is assumed to be fully developed and a flow field previously calculated from physiological aortic flow was used for the calculation of concentration fields. Our results show that even under normal physiological conditions, there exists very low O₂ tension region in the middle of the vessel tissue. The secondary flow causes to make the minimum of oxygen tension near the inner side of bend. The tension near the inside is 20% less than that of the outside. This nonuniformity of oxygen tension in the circumferential direction may be associated with the localized formation of atherosclerotic lesions.

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Limit conditions for the existence of steady-state countercurrent annular flow have been studied analytically, including laminar, transition, and turbulent states of both the core gas and liquid film flow. A new method is developed to determine the limit conditions effectively by computer, and it reveals that the major cause of the limit conditions is interfacial shear stress between the two fluids and its characteristics. Then, based on this finding, a non-α model, assuming no effects of the void fraction α, is introduced in addition to an a model taking the effect of a into consideration. The limit conditions thus predicted compare fairly well with experimental data regarding the CHF of boiling in a bottom-closed vertical tube as well as the onset of flooding.

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In the present report, boiling incipience is investigated for application of pool boiling for electronic device cooling. First, the effect of system subcooling preceding boiling incipience on the incipient wall superheat is experimentally investigated. The surface exposed to a subcooled state shows a considerable temperature overshoot before boiling incipience, and the incipient wall super-heat is independent of the degree of system subcooiling. It is shown that such results can be understood in terms of the stability theory of preexisting nuclei trapped in doubly re-entrant cavities. Next, the reduction of the temperature overshoot by impingement of gas bubbles upon the surface is examined. Results show that the temperature overshoot can be reduced and controlled by this method.

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Vaporization phenomena of a single liquid droplet on a hot stainless steel surface coated with flame-sprayed zirconia were investigated experimentally. Coating thickness of the test surface was in the range from 0.18 to 0.92 mm. Lifetime curves for several pure liquid drops were measured at surface temperatures up to 1100 K, and time-averaged heat flux transferred from the surface to the drop during its lifetime was analyzed. The results show that the extent of the wide temperature range within which the drop remained in direct contact with the surface and vaporized quickly was kept almost constant for thicknesses of more than about 0.3 mm owing to low thermal conductivity of the coating layer. The quantity of heat transferred from the surface during a given period of time, calculated from one-dimensional analysis, also showed a similar dependency on the coating thickness.

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Radiation transfer in fibrous media with large size parameters has been numerically investigatad using a pseudo-continuous model. In this study, first, we examine how the scattering from a single fiber can be approximated by the specular reflection on the fiber surface and the Fraunhofer diffraction of a rectangular aperture which is considered to be a single fiber. Considering the Fraunhofer diffraction and specular reflection, we derive approximate solutions for estimating the optical characteristics of fibers, such as extinction and scattering efficiencies, which are required in this model. By comparing the approximate solutions with the conventional exact solutions, it is shown that the approximate solutions are useful at size parameters of more than 50 and at absorption indexes of more than 0.1. Furthermore, with use of the optical characteristics obtained by the approximate solutions in combination with the conventional exact solutions, radiation transfer in two types of planar fibrous media with typical fiber orientations is estimated, and the effects of the optical constant of fibers, fiber diameter and the orientation on the radiation transfer in the media are presented.

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Previously, in the 1st report, we investigated the anisotropy of the thermal diffusivity of molded PMMA samples. In the 2nd report, anisotropic behavior of molten PS polymer in steady flow was investigated with various shear rates. It was confirmed that the anisotropy of the thermal diffusivity was caused by the molecular orientation in the shear flow region. In the present paper, the anisotropy of thermal diffusivity under a transient state in the case of sudden loading or unloading of the shear stress was measured by the forced Rayleigh scattering method used in the previous reports. It was shown that "overshoot" phenomenon of thermal diffusivity took place under sudden loading of shear stress and the "relaxation" phenomenon of molecular orientation was observed in the case of stress unloading. The transient values of thermal diffusivity in the direction parallel to the flow, and those perpendicular to the flow, were dependent on the initial temperature and the magnitude of the shear stress.

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A numerical method for predicting radiation heat transfer from axisymmetric bodies composed of numerous arbitrary ring elements is presented. Each ring element has the combined characteristics of specular and diffuse surfaces. The accuracy of the method is checked using a simple configuration, and good agreement between the present numerical and analytical solutions is obtained. The effect of specular reflectivity is investigated using the simple configuration. As a numerical example, radiation heat transfer of the Czochralski crystal growth furnace is investigated. The present radiation transfer method is combined with the finite element package, ABAQUS for conduction analysis.

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Radial rotor ducts have been used in the rotor core as one of the better methods for cooling the rotor core and conductors. However, the heat transfer coefficient is not clear. This paper describes the experimental results regarding heat transfer performance, where the rotational numbers are from 0 to 1800 rpm and Reynolds numbers are from 700 to 6000. The relationship of the average Nusselt numbers to each Reynolds number was clarified using the rotational numbers as parameters, and then expressed graphically. When Reynolds numbers are over about 2000, the average Nusselt numbers are strongly affected by the velocity of air flow through the radial rotor duct. When Reynolds numbers are less than about 2000, the average Nusselt numbers are also strongly affected by the rotational numbers. Additionaly, when the flow path in the radial rotor duct is shortened, the average Nusselt numbers increase and when the duct width is reduced, they decrease.

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Natural convection heat transfer from uniformly heated horizontal cylinders to air was investigated experimentally for a single row of 5 cylinders and 5×5 cylinder banks in an in-line arrangement. The heat transfer coefficients for five cylinders arranged in a vertical array were determined varying cylinder spacings in the horizontal and the vertical directions. Correlation equations evaluating average heat transfer coefficients were obtained for a single row and banks of cylinders.

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Natural convection heat transfer to air from an array of five vertical parallel plane plates has been studied experimentally. Measurements of plate surface temperature and velocity between the plates are made under the condition of uniform surface heat flux. The local Nusselt numbers along the central line of the plates are obtained. The induced flow rate between the plates is estimated from the measured velocity profiles. The experimental results are compared with the numerical solution obtained by Miyatake and Fujii for two vertical parallel plane plates.

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This study discusses the solar desiccant system using adsorbent, specifically an "integrated desiccant/regenerator" using direct solar energy as the heat source for efficient regeneration of adsorbent. The objective of this study is to propose the integrated desiccant/regenerator in which adsorbent directly absorbs solar radiation and is heated for regeneration. Another objective is to obtain the regeneration characteristics in the equipment as proposed by experiments. In this study, silica gel is used as an adsorbent.

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In this paper, we report a numerical study concerning the effects of thermal molding conditions on the residual stress and birefringence developments frozen in an injection-molded polymer strip. In our numerical calculation, the residual stress frozen in the injection-molded polymer was considered in terms of flow-induced shear stress and cooling-induced thermal stress. Profiles of the residual birefringence were obtained from these stresses using the rheooptical law. The numerical results showed that the residual stress frozen into the injection-molded polymer strip is mainly affected by the cooling rate of the strip while the residual birefringence is dominated by the temperature and velocity of the injected polymer melt. This indicates that the residual stress and residual birefringence can be reduced by controlling the heat transfer during the filling and cooling stages, respectively.

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The surface deactivation rates of singlet oxygen (¹Δ_g) on inactive materials and SUS316L have been measured with the use of a flow tube system, which generates the excited oxygen in a low concentration in pure oxygen flow by microwave discharge. The first-order surface deactivation probabilities have been determined from measurements of the emission intensity decay of the excited oxygen and analysis of the flow fields in the circular tube. The first-order deactivation probabilities measured on the inactive materials slightly depend on the concentration of the excited oxygen, which indicates the possibility that the surface reaction has a higher-order reaction besides the first-order reaction. The inactive materials are in the following relation in their reactivity to deactivate the excited oxygen : Pyrex>PVC>SiO₂>PFA>PTFE. In addition, the deactivation probability on SUS316L is about three orders higher than those on the inactive materials.

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The effects of the single-longitudinal-mode (single-mode) pump beam on CARS thermometry have been investigated in the temperature range of 300-800 K for pressures of 0.1-3.0 MPa. The accuracy of temperature measurement of averaged CARS measurements, in the case of a multi-longitudinal-mode pump beam, was improved from 40 K to 20 K. The accuracy of the pseudo-single -shot CARS method, in which the single-shot CARS spectrum is normalized by the averaged reference spectrum, was 40 K. The advantages of using the single-mode pump beam are as follws : (1) shorter computational time of the theoretical spectra, (2) determination of the accurate instrumental function, (3) increase of the temperature change of the CARS spectral profile, (4) improve-ment of the reproducibility of the Stokes beam spectral profilie, and (5) elimination of the shot-to-shot spectral profile variation of the pump beam.

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The acoustic excited diffusion flames established in a plane mixing layer with coherent structure are investigated experimentally to obtain detailed knowledge of active control of the combustion process, such as the adaptability of combustion properties to the actions of actuators. A planar loudspeaker flush-mounted on a duct wall at the test section is used to introduce acoustic excitation in the flame region. Detailed flow visualization and spectral analyses of temperature and pressure fluctuations are made to examine the effects of the excitation on over all combustion properties. The results show that the acoustic excitation increases the combustion intensity, makes close and clear the relationship between organized eddies and flame shape, and greatly enhances the periodicity of the organized eddying motion, which plays an important role in the transport process. The spectral profiles of sound pressure in the duct also indicate that the low-frequency component (0-400 Hz), which is difficult to eliminate with any silencing device, is effectively suppressed by the acoustic excitation, which is of great advantage in soundproofing.

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A method for applying the agglomerate scattering theory to polydisperse soot agglomerates was developed, and the morphology and size distribution of the agglomerates suspended in a premixed ethylene-air flame of 1.95 equivalence ratio were inferred from data of the dissymmetry ratio in the differential scattering intensity and transmission electron microscopy (TEM). As a result, it was found that the size distribution diagram obtained by the TEM method was skewed to the right due to the coalescence on the collodion membrane for particle sampling, and that, if the optical method was applied assuming the monodispersity of soot agglomerates, their size was overestimated to be 1.8 to 3.1 times the TEM geometric mean value by volume, which had already shifted upward due to coalescence. The larger geometric standard deviation is assumed ; the smaller geometric mean size (number of primary spherical particles) is inferred by the optical technique. The effect of the geometric standard deviation is less prominent with single straight chains assumed for soot morphology than with double straight chains, although no vital difference is observed. As the real part of the complex refractive index is increased or the imaginary part is decreased, a smaller geometric mean size is inferred, as well as the increased effect of the geometric standard deviation, although, again, no vital difference is observed.

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The transition from laminar to turbulent modes of an ethylene jet flame was investigated using two-dimensional instantaneous photography of turbulent eddies, by means of a laser-light sheeting method. Observations were made for the eddies around the break point in the fuel flow and the flame. The results show that in the laminar region the fuel flow is bent due to instability in the shear layer, whereas the outer soot layer has little curvature because of the high viscosity in hot layer. In the transient region, eddies generated in the fuel flow deform the outer soot layer. Numerical calculations were performed for predicting fluid motions due to interaction between density and pressure gradients in the flame boundary. The results show that the pressure gradients generate the vorticity in a medium of varying density along the flame. Deformation and stretching of the flame boundary take place once the vorticity becomes stronger than the dissipation due to viscosity.

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The local reaction zone thicknesses of high intensity turbulent premixed flames, whose Kolmogoroff scale is smaller than a laminar premixed flame thickness have been examined for various mixture ratios by using a microelectrostatic probe with two identical sensors. For a wide range of mixture ratios, the local reaction zone thickness of high intensity turbulent premixed flame is similar to the laminar premixed flame thickness. It is presumed that even in intense turbulence, small scale turbulent eddies may not survive in the local reaction zone. The inner structure of a laminar premixed flame would be preserved at the local reaction zone of turbulent premixed flames.

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