Thrust generation by the surface of a flexible thin planar body performing progressive wave motions was studied by fluid dynamics using a method of unsteady distributed vortices. The thrust by constant speed progressive waves was surveyed for constant amplitudes and for amplitudes expanding toward its rear edge. The resuits about thrust coefficients and propulsion efficiencies are described in terms of a ratio of the phase speed of the progressive waves to the flows speed as well as reduced frequencies and amplitude ratios. The tendency of the thrust generation is understood clearly by the speed ratios. Detailed information about pressure distributions and thrust generation density along the body length has also been obtained.

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In case of an emergency fire in tunnel, proper operation of the ventilation system which controls the thermal fume and smoke induced by fire accident to remain an available evacuation and extinction envjronment is very immportant. In this paper, a three-dimensional numerical simulator using LES turbulence model is developed and the themal behaviors of an emergency fire in tunnels is investigated. Furthermore, several modelling parameters applied in this simulator are examined. Comparison of the numerical simulation results and the fire test results obtained from a real vehicle tunnel shows that the present simulator has a good reliability on the numerical analysis of emergency fire in vehicle tullnels.

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Large eddy simulations (LES) of gas-solid turbulent channel flow were performed with considering inter-particle collision in order to study the preferential concentration observed in previous experiments. Trajectories of individual particles were pursued with the Lagrangian method and inter-particle collision was dealt with the deterministic method. Spatial structure of particle distribution was observed by visualizing the calculated flow field. Futhermore, the effects of Stokes number and inter-particle collision on the structure of particle distribution were discussed. It is found that particles of large Stokes number disperse nearly uniformly and particles of small Stokes number tend to form preferential concentration. Structure and scale of particel clouds calculated with the effect of inter-particle collision were in good agreement with previous experimental observations.

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When hydraulic machinery start to operate, the flow around the blade elements has to be typically transient. To clarify such flow behavior, we attempt numerical simulations of the viscous transient flow around a typical hydrofoil, by using the QUICK method of high resolution accuracy. For such a viscous flow, our simulations show not only the step response of expectable through potential concept, but also the rather slow viscous response, which is almost linear to the elapse time t.

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This study was performed to examine three-dimensional flow structures in a grooved channel by the finite volume method. The three-dimensional effects are dominant near the side walls of the channel at low Reynolds numbers. Spanwise spiraling flows developing from the side walls towards the symmetry plane of the channel are identified in the groove region of the grooved channel as the Reynolds number increases. A comparison of two-and three-dimensional calculations reveals that the three-dimensional maximum streamwise velocity in the by-pass ragionis about 10% larger than the two-dimensional one.

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Three dimensional numerical simulations were made on supersonic compressible flows in disk channels in order to obtain knowledge which is important for designing a disk MHD channel. Effects of the cross sectional area ratio and of channel height on both flow field and total pressure loss were investigated. For small area ratios, the flow Mach number decreased along the radial direction and total pressure loss was induced mainly by pseudo-shock wave and boundary layer separations. It was clarified that an optimal area ratio which makes the total pressure loss minimum, exits and that the total pressure loss decreases with an increase in the channel height. Furthermore, new thin swirl vanes with a simple shape were proposed in order to improve the disk MHD generator performance. The numerical simulations on the flow in which swirl vanes with different shapes are installed, have suggested that although the elliptic shape can provide a larger swirl compared with the circular shape, the total pressure loss in the downstream becomes larger owing to a larger viscous dissipation in the wake.

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This paper describes the hydrodynamic characteristics of the abrasive water jet (AWJ) flowing within smallbored nozzles. For analyzing high-speed water jet containing fine solid particles, we introduce the slip velocity model to the one-dimensional momentum equation and estimate the axial distribution of pressure and phase-velocities within the nozzle. The analytical result shows that (1) the pressure within nozzle is always in the vacuum side in case of high-speed water jet and (2) the pressure along the nozzle axis is greatly affected with the change in slip ratio. Experimental data using high-speed two speed two-phase flow of air-water mixture coincide with these predicted tendency. The data also show that there is steep pressure rise at the nozzle exit. From the data analysis, it is concluded that gas phase velocity exceeds its sonic velocity in some region within the nozzle and the phenomena like as normal shock wave may occur in the AWJ nozzle.

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The experimental results on the abrasive water jet (AWJ) are described in this paper. AWJ is the high-speed water jet containing solid particles and is used for cutting of various industrial materials. In order to obtain the velocities of solid, gas and liquid phases at the mixing nozzle exit, the momentum of jet was measured. Phase velocity distribution in the axial direction of jet was also estimated based on the measured pressure distribution in the AWJ nozzle with the aid of the continuous and the momentum equations. The result shows that the decrease of the liquid phase velocity in the mixing nozzle is small in the case of the gas liquid two phase flow, and the velocity of liquid phase is remarkably reduced on the contrary in the gas liquid-solid three-phase flow. In the latter case, the total momentum of jet is reduced comparing with two phase flow. It is also found that the mean velocity of solid particles at the mixing nozzle exit is about 30% of the velocity of liquid phase.

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This paper deals with a possibility of the control of cavitation in submerged water jet. A cylindrical type of cavitator is set in nozzle in order to generate vortex ring cavitation in the near wake region of the cavitator. Cavitation intensity is controlled by changing the length of the cavitator, with which the thickness of boundary layer at the trailing edge of the cavitator and the size of vortex ring are concerned. It is clarified that the present method can control effectively cavitation intensity and that there are great differences in impulse force depending on the standoff distance and the cavitator length. Impulse force in cavitation-controlled conditions is of the magnitude of three times lager than that in uncontrolled ones.

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This paper describes a new time marching calculation of blade cavitation using a linearized free streamline theory with a singularity method. In this calculation, closed cavity models for partial and super-cavitation are combined to simulate the transitional cavity oscillation between partial and super-cavitation. The results for partial cavitation instabilites on a single blade located in a 2-D channel are presented. Although the re entrant jet is not taken into account, the transitional cavity oscillation with large amplitude, which is known to occur when the cavity length exceeds 75% of chord length, was simulated fairly well. The partial cavity oscillation with relatively high frequency was also well simulated with the frequency agreeing with that of previous stability analysis and of experiments. The present calculation can be easily extended to simulate other cavity instabilities in pumps or cascades.

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It is well known that a cloud cavitation is one of the most destructive forms of cavitation. The set of equations for the motion of a spherical bubble cloud is formulated. Behavior of bubble clouds are simulated numerically when the surrounding pressure is decreased from 50 kPa to a 10 kPa and then increased to 50 kPa. To study the collapse of cloud cavitation more strictly, the internal phenomena of bubble and the compressibility of liquid are considered in the governing equations. An inward propagating shock wave is formed during the collapse of bubble cloud and the shock wave is focused in the center region of the cloud. This makes a violent bubble collapse, which causes a high emitted pressure from the bubbles, which is several hundreds times larger than the single bubble collapse. Moreover, relationship between the cloud collapse and cavitation erosion is studied.

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An air-water bubbling jet was generated vertically upward along a vertical fiat plate. The liquid flow characteristics represented by the axial mean velocity and the root mean-square value of the axial turbulence component, designated by u^^- and u'_rms, were measured with a two-channel laser Doppler velocimeter. The horizontal distributions of u^^- and u'_rms followed their respective similar distributions in the vertical region where the buoyancy force acting on bubbles governs the flow field just like the distributions of bubble frequency and void fraction. An empirical equation was proposed for the horizontal distribution of u^^-. The skewness and flatness factors for the axial turbulence component were also discussed to describe the structure of turbulence in more detail.

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In a multiparticle system, the drag force acting on each constituent particle, F_d, is larger than that acting on an isolated single particle ill an infinite expanse of fluid, F_d∞. The drag force is affected not only by the fractional void volum, ε, but also by particle Reynolds number, Re_p. The effect of particle concentration on the drag force in a multiparticle system had been mainly measured by Steinour⁽¹⁾, Ergun⁽²⁾, and Wen and Yu⁽³⁾. However, those results are not applicable in whole ranges of ε and Re_p, and it seems that some results overestimate F_d acting on uniformly dispersed spherical particles. In this study, we have directly measured the drag force acting on the particle cluster which contains about 1 000 single-sized spherical particles by using a weighing apparatus under the conditions of 0.7≤Re_p≤1 000 and 0.2595≤ε≤0.8869. The experimental data in the viscous flow region (Re_p≤1) are fitted to the data obtained by Steinour. The ratio of drag forces, ζ=F_d/F_d∞, slightly decreases with increasing Re_p. When ε is large, the decrease of ζ becomes likely to occur under the conditions of lower Re_p.

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A finite difference lattice Boltzmann method (FDLBM) for two-phase flows pertinent to isothermal nonideal fluids is proposed. This FDLBM introduces a pseudo-potential and recovers a full set of hydrodynamic equations for nonideal fluid through the Chapman-Enskog expansion procedure. Numerical measurement of surface tension agrees well with theoretical predictions. Simulations of two-phase phenomena, including phase-transition and droplets collision are carried out, showing applicability of the model for two-phase flows. Numerical stability of the scheme is ensured by using finite difference Lattice Boltzmann method. This LB model retains advantages of conventional LB methods such as a linear advection in the kinetic equation and parallel nature in computing.

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Static calibrations of a flush-mounted hot film gage are carried out on a wall of a wind tunnel at zero and favorable stream-wise pressure gradients. The calibrations at the zero pressure gradient show that the cube root of time-averaged wall shear stress, T^^-1/3_w is proportional to [E^^-2-E^^-2₀], in which is time-averaged output voltage of the constant temperature anemometer and E^^-₀ is one in the absence of a main stream except for the natural convection flow over the gage. This relationship helps to eliminate disadvanteges caused by thermal conduction into the hot-film substrate and thermal radiation from the hot film. Under the favorable pressure gradients, this relationship needs to be modified using a term of pressure gradiant. A formula for this pressure gradient modification is proposed in this paper. This formula is applied to study the fluctuations of the wall shear stress in relation to the coherent structure of turbulent boundary layers.

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In the present study the dynamic lift and drag acting on the pitching airfoils such as a flat plate, NACA 0010, NACA 0020, NACA 65-0910 and BTE have been measured by using a six-axes sensor in a water tunnel at low Reynolds number region under the condition of various pitching frequencies. The unsteady characteristics of the dynamic lift and drag have been compared with the quasi-steady ones which are measured under the stationary condition. The pitching motion is available for keeping the lift higher after the separation occurs. The characteristics of the dynamic lift is quite different from the quasi-steady one at high pitching frequency region such as 3.0 Hz. As the pitching frequency decreases, the amplitude of the dynamic lift becomes closer to the quasi-steady one. However, the phase remains different between the steady and unsteady conditions even at low pitching frequency such as 0.05 Hz. On the other hand, the dynamic drag is governed strongly by the angle of attack.

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The unsteady flow field of an incompressible viscous fluid around an impulsively started sphere in slow motion is studied in detail. Integral expressions are derived from the nonlinear vorticity equation and are solved by the method of matched asymptotic expansions. The present analysis shows that five regions are necessary to complete the present singular perturbation problem and the matching with respect to time coordinate is not required in order to obtain unique solutions unlike earlier theories. In the present paper, the transient drag forces for the beginning of motion, intermediate time of motion, and the long-time of motion are obtained in an alternative form and compared with earlier results.

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In the present study, a secondary flow structure in a right angle branch has been expemimentally studied in laminar steady flow by flow visualization. A side branch 14 mm in diameter bifurcates at right angle from a trunk 24 mm in diameter, and both upstream and downstream corners at the entrance of the side branch are square edge. After bifurcating, the secondary flow is induced in the side branch and also a reversing flow is formed downstream of the upstream corner in the side branch. There is asymmetrical pair of large vortices in the side branch basically. There is another pair of small vortices within the side branch including the reversing flow immediately downstream of the upstream corner. Furthermore, in the region downstream of the reattachment point the symmetrical plane of vortices inclines with respect to the common median plane.

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As a fundamental study on a heat transport system utilizing a magnetic fluid two-phase flow, forced convective boiling heat transfer of water-solvent magnetic fluid with magnetite particles of 29.9 wt% was investigated experimentally in a thin tube 4.01 mm in diameter under a magnetic field with constant gradient of 3.85×10⁶ A/m². When a region downstream from the point of maximum magnetic field strength was heated, the boiling heat transfer was reduced by the application of a magnetic field. When a upstream region was heated, the boiling heat transfer was reduced and wall temperature fluctuated by the field.

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In this report, we present new results of simultaneous measurements of velocity and scalar quantity in an axisymmetric turbulent jet of water solution of high Schmidt number matter. The diffusing fluid is a water solution of a commercial dye (Sc≃3 800), and an issuing Reynolds number is 6 400. A new combined probe of a reflection type of fiber optic concentration sensor and an I-type hot film has been developed for the simultaneous measurement of concentration and axial velocity. At first, we examined the interference effects of the fiber sensor and the hot film, and confirmed that the reliable data can be obtained when two probes are set at a distance of 0.3 mm which is smaller than the Taylor micro scale of the velocity field (x/D≥30). Then, we measured concentration and axial velocity simultaneously. It is found that the correlation between concentration fuctuation and axial velocity fluctuation has positive value in fully developed turbulent jet and that the turbulent axial mass flux on the jet centerline is in inverse proportion to the square of the downstream distance.

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This study describes a velocity profile and a pressure distribution in the hydraulic spool valve in low pressure. The spool valve is made of acrylic resin with the spool diameter of 24 mm. Three slit widths of 0.8 mm, 1.2 mm and 1.6 mm are employed in the experiment. Velocity profile at median plane was measured using laser Doppler velocimeter. Upstream region of the slit, velocity is maximum near the wall of spool in annulus region between two concentric cylinders (d=13 mm and D=24 mm). In the downstream region of the slit, jet changes from straight flow to the attaching flow on the side wall of housing, when the Reynolds number increases. Three dimensional numerical analysis was performed by a finite element method under conditions of steady and turbulent. Calculated velocity profiles in the upstream region of the slit agree with experimental ones, and flow patterns of jet in the downstream region agree with measurements at Re>10 000. Calculated pressure distributions were integrated at both ring-shaped surfaces of the slit side and the upstream side of spool, and axial force acting on spool was calculated.

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Effects of gas molecular weights on laser opto-microengine performance are discussed in this paper. Helium, argon, and xenon are used as an environmental gas for operating of a microengine. With the decrease of the gas molecular weights, the maximum twisted torque of the microengine increases. The rotational rate of the microengine also increases with the decrease of the gas molecular weights. The twisted torque and the rotational rate of the microengine with helium are the greatest. Gas molecular motions around the microengine are numerically simulated by Direct Simulation Monte Carlo method. The numerical results by the DSMC method show that the pressure differences between forward and backward surfaces of the engine blades are dependent on the gas molecular weights. The surface temperature and rotational rate of rotating blades of the microengine were measured simultaneously.

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This paper describes the performance of a sirocco fan with eccentric inlet nozzle. The effects of the eccentric position of the inlet nozzle on the pressure coefficient and internal flow of the fan are experimentally investigated for two kinds of impeller. It is found that, in case that the eccentric position is located far upstream of scroll exit, the pressure coefficient is considerably higher than that without eccentricity. In this eccentric fan a circulating flow through shroud clearance from the impeller outlet to inlet is formed. As the circulating flow blocks the suction flow entering into impeller inlet, the effective flow region of the cascade is narrowed. Therefore the flow velocity through the cascades increases and the work done by it increases, so the total pressure of the fan increases. As some fluid in the scroll circulates through shroud clearance, the remaining fluid, which flows into an exit duct, suddenly expands. Therefore a large static pressure recovery is obtained in the scroll.

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The experimental studies are conducted to reveal the mechanism of stall margin improvement of an axial flow fan by injection or suction from the end wall. In case of injection, the largest improvement is obtained by the injection at about 0.14∼0.21 times axial chord length downstream from leading edge. The reason for large improvement is that stall vortex, shed intermittent separation vortex and tip leakage vortex are dissipated by this injection, and also that this blowing suppresses the separation of boundary layer. In case of suction, the largest improvement is found for the suction from the end wall near leading edge. The amplitude of periodic static pressure after stall inception becomes smaller in comparison with injection cases. These effects are increased with the increase of suction flow rate, because the discharge of the vortex occurs more easily. On the other hand, the suction from the upstream of leading edge reduces the axial velocity near rotor tip, and then it induces stall. Also we tried to visualize the tip region flow. The suppression mechanism is discussed based on the visualization. The suppression of stall is successfully photographed.

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In order to investigate lubrication characteristics between rotor and spherical valve plate, a mathematical model of rotor motion has been presented for a piston rod driving type bent-axis-type axial piston pump. The forces and the moments acting on the rotor through the piston rod have been derived from geometric analysis of rotor driving mechanism with the piston rod. An analysis model on mixed lubrication between the rotor and the spherical valve plate has been shown using Average-Flow-Model by Patir-Cheng and the contact theory by Greenwood-Tripp, respectively. In addition, bearing part between the rotor and shaft, supporting element of the rotor, has been regarded as squeeze film bearing. The simulation for the lubrication characteristics, such as minimum film thickness, its occurring position and friction loss between the rotor and the spherical valve plate, will be demonstrated in the paper, part 2.

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The paper, part 1, has proposed a mathematical model of rotor motion for piston rod driving type bent axis type axial piston pump in order to study lubrication characteristics between rotor and spherical valve plate. The numerical calculations have been carried out under operating conditions and specifications. The calculation results have been compared with experimental ones given by previous papers. It is found that (1) the rotor moves to delivery area and its axis tilts to one with its rotation, (2) film thickness between the rotor and the spherical valve plate minimizes at inside sealing part and the center of fluctuation locates near neutral point of the delivery area, and (3) the minimum film thickness and friction moment are greatly influenced by rotational speed, viscosity and dimension of sealing part on the spherical valve plate.

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Insects augment oxygen supply using convective transport during flight in two ways: with deforming tracheae by surrounding muscles movement (muscle pumping) and with contracting air sacs by exoskeleton movement (abdominal or thoracic pumping). However, because induced flow inside tracheae is difficult to measure, it is not known how the convective transport actually contributes. By comparison between direct measurement of oxygen partial pressure in a flight muscle based on electrochemical method and flight/ventilation activities in a bumblebee, Bumbus hypocrita hypocruta, a method was developed for estimating gas transport efficiency. Oxygen partial pressure, P_O2, in the bee periodically fluctuated with discontinuous abdominal movement in normal air. While the P_O2 strongly varied among individuals in normal air, the P_O2 took a unique value in oxygen poor air (≤8%). By enhancing ventilation, the bee could respire in an oxygen poor atmosphere up to 2%. Furthermore, the bee could fly in an atmosphere of 6%, in which the P_O2 decreased to 0.7%. Estimated efficiency of the gas transport increases with atmospheric oxygen concentration decreases.

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A number of self-rectifying air turbines for wave power conversion have been proposed over the last decade. However, the comparison of their characteristics has not been made so far. This paper reviews the present state of the art of the self-rectifying air turbines for wave energy conversion, and shows the comparison of the performances of the turbines. In order to clarify the turbine characteristics, the experimental investigations have been performed under steady flow conditions. And then, the starting and running characteristics in irregular flow have been obtained by a computer simulation. As a result, it is clarified that the impulse type turbine is superior to the Wells type turbine in the overall characteristics.

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We calculated the speed and efficiency of bacterium swimming motion by use of the slender body theory developed by Higdon. A bacterium model consists of a spherical cell and a rotating helical flagellum is adopted. The results agree well with those of the boundary element method. The computational time of the slender body theory is about 1/400 of that of the boundary element method. We also carried out optimization of the shape of the flagellum with respect to the highest speed and the most efficient swimming. The difference of these two shapes is apparent in the radii of the flagellar helices, and associates with counter rotation of each cell that is keeping torque balance. The flagellar shape of the highest efficiency resembles the observed data for Vibrio aiginolyticus. Flagella of the bacterium seem to be optimized for efficiency rather than swimming speed.

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A three dimensional steady numerical analysis has been made for both of staggered array and in-lined array of two-row plate-finned tubes heat exchanger unit located in a uniform flow. The structures of the flow and thermal fields have been examined for conduction-convection conjugate heat transfer problem of the studied fin-and-tube model. The results of the numerical analysis revealed some important effects of geometric parameters on heat transfer from the fin-and-tube surface for each array of two-row tubes. The effects of fin thickness, fin pitch, fin length, tube pitch and Reynolds number on heat exchange rate, Nusselt number, heat transfer rate, and pressure coefficient were examined parametrically. Though space mean Nusselt number and heat transfer rate have no big difference between the two array cases, slightly better heat transfer performance is attained in the staggered array case as Reynolds number or fin pitch is increased. On the contrary, pressure loss obtained in the staggered array case is larger than that obtained in the in-lined array case.

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Experimental study was performed on heat transfer of an open thermosyphon with constant wall heat flux. Water and aqueous glycerin were used as working fluids. Experimental range of modified Rayligh Number was 1×10³<Ra_m<3×10⁵. Average and local heat transfer coefficients, vertical temperatures distributions of the tube wall and fluid at the center line of the tu be, temperature fluctuation of the fluid were measured. Flow patterns were observed by adding tracer powder in the fluid. Fluid velocities were measured by L. D. V. Experimental results indicate that there exists three different heat transfer characteristics and corresponding flow patterns. For 1×10³<Ra_m<4×10³, flow was laminar and thermal boundary layer reaches near the center of the tube. Heat was exchanged between wall and descending flow. Wall temperature rose towards downward. For 4×10³<Ra_m<3×10⁴, no turbulence was observed in the flow and thermal boundary layer was localized in the vicinity of the wall. Wall temperature rose towards upward. For 3×10⁴<Ra_m<3×10⁵, flow is considerably disturbed by the mixing of upward and downward flow in the upper part of the tube. However, flow is almost laminar in the lower part of the tube. Reduction of flow rate induced by the flow mixing at high Ra_m would be one of the major causes of the deterioration of heat transfer from the Lighthill's theory.

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The frequency of appearance of the surface-renewal eddies below a wind-driven air-water interface in a wind-wave tank was measured to discuss the effects of liquid viscosity on the heat and mass transfer across the air-water interface. The restilts show that the convertable relation which represents the proportionality between the mass transfer coefficient and Sc^-1/2 is incorrect in the wind-driven field, since the frequency of the surface-renewal eddies controlling heat and mass transfer is independent of the liquid kinematic viscosity. Furthermore, the heat transfer coefficient on the liquid side was measured for the air-water interface in the wind-wave tank. The results show that the conventional bulk method for estimating the heat flux at the air-water interface is not reliable. The similarity between heat and mass transfer at the air-water interface can be seen in the high wind speed region where the effects of the tiny surface-active impurities on the molecular diffusivity at the interface are removed by intense wave-breaking. However, the similarity disappears in the lower wind speed region. The damping effect of the surface active impurities on the heat transfer is larger than that on the mass transfer.

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Effect of fin on heat transfer around a tube was investigated experimentally. A test tube of 30 mm diameter was installed in a test section of an open type wind tunnel as a single tube, or as a center tube in a single tube row and in a tube bundle of staggered layout. Fins made by paper were put on the test tube having certain fin spacing. It was clarified from the experiment, that the local heat transfer coefficient around the tube degrades with decreasing fin spacing, especially on the down-stream-side of the tube, and the minimum fin spacing where the effect of fin begins to appear is the largest for the single tube and the smallest for the tube bundle.

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The convective mass transfer in a channel with the rough surface is investigated by the use of the cellular automaton method. The Greatz problem is simulated by the cellular automaton method. It is shown that the simulation result is consistent with the analytical solution. The cellular automaton method is applied to the mass transfer problem in the channel flow with the rough surface. The local Sherwood number and bulk mean concentration are calculated. It is shown that the mass transfer rate increases with the size of roughness.

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The numerical simulations have been performed to clarify the effects of the turbulence in the liquid on the deformation of liquid jet surface issued into the air flow. The turbulences in the liquid jet were simulated by the Rankin vortices, and the liquid jet surface was tracked numerically by the VOF (Volume Of Fluid) method. By the numerical simulations, the onset of the protrusions on the liquid jet surface is caused by the vortices in the liquid, and the surrounding air flow plays the important role for the amplification of the protrusions. The amplification rate of the trough displacement is proportinal to the air-to-liquid velocity ratio. At large imposed vortex intensity, the trough displacement increases with the vortex intensity. On the other hand, at small imposed vortex intensity, the amplification of the trough displacement is affected by other factors except vortex intensity.

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The clarification of the behavior of a liquid jet injected into a subsonic airstream is very important for the design of the liquid-fueled combustor, such as a ramjet or gas turbine combustor. The behavior of a liquid jet is related to the disintegration mechanism, and eventually effects spray characteristics. In this paper, the trajectory equation of a liquid jet was deduced semi-analytically by assuming the drag of a liquid jet, and calculations from the above equation were compared with measurements. The liquid jet injected into an airstream is deformed by the pressure of the surrounding airstream. The present theory includes the deformation of a liquid jet in a cross section of the jet. The deformation was calculated from the drop oscillation model of Clark. The calculations of the liquid jet penetration from the semi-analytical equation were coincident well with the measurements except for a few experimental conditions.

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Critical heat flux has been measured during natural convective boiling of water on uniformly heated outer tube in vertical annular tubes. The experiment was carried out at atmospheric pressure for the clearance of S 1 to 4 mm, the heated tube diameter of 9 to 17 mm, the annular tube length of 100 to 1 000 mm. The similarity of CHF between annular configurations of inner and outer heated tubes and simple heated tube can be clearly elucidated based on the characteristics of equivalent heated diameter. The CHF measured for S=1 mm can be predicted well by existing correlation for annular tubes and for S=3 and 4 mm by existing correlation for single tubes.

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This paper deals with the continuous production mechanism of slush ice by use of a vertical oscillating cooled wall immersed in ethylene glycol solution. The cooled wall was operated with cyclic horizontally oscillation motion in the test vessel. Experiments were carried out under a variety of conditions, such as both of the acceleration and stroke of the cooled wall, and initial concentration of solution. it was found that ice layer formed on the cooled wall continuously separated from its surface and fine ice crystal became to spread in the test vessel, which reveals the possibility for production of slush ice by the present method. Furthermore, an analysis was performed to determine the separation conditions of ice layer caused by the wall motion. The continuous production range of slush ice was well predicted by the present analysis.

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The two-fluid cycle is considered for municipal solid waste-(MSW) burnt electric power generation, using five kinds of working fluid such as NH₃, C₅H₁₂ and C₆H₆ at the bottoming cycle, which are different from water at the topping cycle. The performance characteristics of the two-fluid cycle are obtained and the optimum cycle conditions, which maximize the plant thermal efficiency, are determined for the respective working fluid. Further, the effects of the parameters such as the terminal temperature difference of the heat exchanger and superheating on the thermal efficiency are clarified. It is shown that the plant thermal efficiency was increased to 19.7% from 17.6% by the adoption of the two-fluid cycle using C₆H₆ as the working fluid and could be improved further by superheating the main vapor at the bottoming side and by preheating the feed-liquid using the bleeding vapor in the bottoming turbine.

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Two types of fuel nozzle are used in a cylindrical furnace which is 1 m in inner diameter and 4.8 m in height. The one is axial injection type with single hole (nozzle 1) where fuel and air flow in the same direction coaxially upward. The other is radial injection type with multi holes (nozzle 2) where fuel and air flow in the crosswise direction. Two types of fuel nozzle form extremely different types of turbulent diffusion flames. Nozzle 1 forms a long flame, while nozzle 2 forms a short flame with recirculating zone at the center of the flame just above the nozzle tip. Measurements of profiles of temperature, species concentration, together with the heat flux to the furnace wall are carried out in a turbulent diffusion flame of propane. Their interconnections with combustion and heat transfer characteristics are investigated and discussed under various furnace operating condition of air swirling, inlet air temperature, recirculating exhaust gas, air ratio, fuel flow rate and type of nozzle.

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Hydrocarbon/oxygen mixture seeded with nitrogen dioxide were ignited by xenon flash photolysis. Combustion appeared uniformly throughout the entire volume. C₂, CH and OH radical emissions were measured under the several initial pressures and equivalence ratios. Two different emission peaks of C₂ and CH were found depending on initial pressure and equivalence ratio. OH emission intensity varies smoothly with time, and increased linearly with pressure. The second emission peaks of C₂ and CH could count among the thermally exited emission because of the matched OH emission peaks. The first ones were considered to he the chemically exited emissions. An attempt is made to explain that the two emission peaks appear by the reaction : CH₂→C^*₂, CH^* (chemical excltation)→C^*₂, CH^* (thermal excitation) associated with polymerization/destruction.

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This paper deals with a simple and reliable technique for simultaneous measurement of velocity and temperature in high-temperature turbulent flows, including combustion. The technique is based on the combination of laser Doppler velocimetry (LDV) and a digitally compensated fine-wire thermocouple. A central issue of this study is to find the applicability and reliability of the technique proposed. For this purpose, a two-thermocouple probe with a fine cold wire (Tagawa, Shimoji and Ohta, 1998), which enables in situ measurement of thermocouple time constants and accurate compensation of the thermocouple response, is combined with LDV. The technique is tested in a turbulent wake behind a heated cylinder, whose thermal field is of ordinary temperature and fluctuates with relatively small amplitude. This enables critical assessment of the measurement accuracy. The results show that the technique is highly reliable and effective for investigating heat transport processes in various non-isothermal turbulent flows.

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Characteristics of methanol reduction and formaldehyde formation with NO_x purification catalyst (NO_x catalyst) have been investigated to know the applicability of NO_x catalyst to lean burn or diesel type methanol engine. The catalysts used in this research were Co-γAl₂O₃ and Sn-Al₂O₃ as examples of NO_x catalysts and Pt-Al₂O₃ as an oxidation catalyst to be compared with NO_x catalyst. Pure γAl₂O₃ was also used additionally. Laboratory experiments were conducted by using above catalysts in oxygen rich atmosphere considering lean burn methanol engines or diesel type methanol engines. Reaction temperature and presenting NO concentration were selected as experimental parameters. The experimental results showed that methanol reduction temperature with NO_x catalyst became around 150°C higher than that with oxidation catalyst and it became closer to engine exhaust gas temperature level. Large amount of formaldehyde was formed during the use of NO_x catalyst at a certain temperature range. The formation temperature range is higher than that with Pt catalyst, which may cause higher formaldehyde formation in the engine exhaust gas. Effect of NO on methanol oxidation and formaldehyde formation characteristics with NO_x catalyst was significant as was observed in oxidation catalysts. With increase in NO, methanol reduction rate became lower and the amount of formaldehyde formation increased.

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The heating value transported by conduction has a lot of cases ignored when heat transfer in combustion chamber of gasoline engine was analyzed. The reason is because the value is smaller than the value of convection generally. But gas flow hardly exists in the vicinity of chamber wall where heat transfer is actually done. In this case it needs to be made clear whether the effect of conduction can be ignored. Therefore analysis and experiments were done with constant volume chamber in this paper. As a result that heat flux which was represented by conduction was let by the next expression. [numerical formula] It became clear that heat loss quantity estimated by, tinis expression was about 30% of true heat loss. And it is supposed that gas flow formed by combustion has influenced remainder 70%.

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To increase the availability of cogeneration, it is desirable to increase the efficiency of power generation from the system, as well as to make the heat-to-power ratio variable corresponding to its demand patterns. A new power recovery system from a gas engine has been invented to attain the purpose. The system utilizes H₂O and NH₃/H₂O mixture. It is a combination of a H₂O steam turbine, an NH₃/H₂O steam turbine, and an NH₃/H₂O refrigerator. The system can recover power not only from the exhaust gas but also from the jacket water. It can extract power effectively from a high temperature down to a low temperature; 30% or more power can be recovered than when using conventional exhaust gas steam turbine. Moreover, it can change the heat-to-power ratio to conform energy supply to energy demand. This paper describes the concept of the system and the simulation results.

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