Drying technique on the basis of Marangoni force is applied to semiconductor or glass substrate drying. In this method, organic vapor such as IPA that decreases surface tension is fed into bath during draining rinse water. Although Marangoni force is expected to enhance removing water from surface, detailed mechanism of the drying process has not been clarified. We analyzed Marangoni force in the neighborhood of the meniscus of substrate using C. F. D. and compared the computational result with the particle removal and adhesion evaluation experiment for both hydrophilic and hydrophobic surface Si wafers. As a result, we find out that the direction of Marangoni force at the top of mensiscus in hydrophobic wafers is opposite to that in hydrophilic wafers. This difference is closely related to the experimental result that particles are effectively removed from hydrophilic wafers and more particles are remained on hydrophobic wafers. Additionally C. F. D. result suggests that Marangoni force depends on the curvature and thickness of boundary layer on the meniscus.

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We have conducted non-equilibrium dynamics simulations to investigate the influence of the parameters, which have appeared in defining the equation of motion, in the dissipative particle dynamics method. The results obtained here are briefly summarized as follows. The theoretical values of the viscosity due to dissipative forces in the H-K theory are in good agreement with the simulaitons results obtained by the non-equilibrium dynamics method, except in the range of small number densities. The results obtained from the Green-Kubo expression by equilibrium simulations are significantly smaller than the theoretical ones. There are restricted conditions for taking appropriate values of the number density, number of particles, time interval, and shear rate to obtain physically reasonable results by means of dissipative particle dynamics simulations.

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Fully-developed flow in a channel subjected to the spanwise rotation was investigated by means of the direct numerical simulation (DNS). Two steps of rotation number, Ro_τ=1 and Ro_τ=2.5, and stationary condition were mainly calculated. The turbulence was enhanced in the pressure side and attenuated in the suction side by increasing the rotation number, but the change was not monotonic.Notable feature was found for the case of Ro_τ≈ 1 : the flow rate takes its maximum ; it fluctuated in time ; the shift of Reynolds shear stress almost teminated. For higher rotation rate, roll-cell vortices and, as a consequence, the constant-gradient in the mean velocity profile were observed. Furthermore, the log profile was evident only in the region blown from the pressure side by the roll-cell vortices. Due to these observations, it was found that the rotation number 'unity' was a turning point of the change of dominant structures : the near-wall vortices in lower rotation and the large-scale roll-cell vortices in higher.

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Pitot tube flow metering technique has been used to measure pulsating flow from a vehicles engine exhaust. In general, flow metering techniques that utilize differential pressure measurements based on the Bernoulli's theory likely to show erroneous reading when measuring an average flow rate of pulsating flow. The primary reason for this is the non-linear relationship between the differential pressure and the flow rate, i.e. the flow rate is proportional to the square root of the differential pressure. Thus, an average of the differential pressure does not give an average of pulsating flow. In the present study, fast response pressure transducers have been used to measure the pulsating pressure as raw as possible. Then, the pulsating differential pressure is converted to flow rate keeping the pulsation not averaged. An average of the flow rate is then calculated in flow rate domain in order to maintain the linearity of before and after the averaging. The peak amplitude of a pulsation measured here was about 1800 LPM at the average flow rate of 70 LPM when an engine was idling. This measurement has been confirmed by measuring the pulsation with a gas analyzer. The result here implies large amount of back and forth gas movement in the exhaust tube. Such amount of pulsation can cause maximum five times higher erroneous result with the pressure domain averaging when compared to a flow rate domain averaging.

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In a zero-pressure gradient turbulent boundary layer, the multi-point measurement by 24 ch I-probes is performed. The relation between coherent structures and logarithmic velocity profile is studied by way of proper orthogonal decomposition technique and the stochastic estimation. It is found that the existence of coherent structures are necessary condition for the universal velocity profile, however it is not enough. Small-scale motions are also necessary to realize the log-law profile. The probability density profile in the overlap region is studied, and as a result, the invariant assumption of PDF in relation to the coherent structure is obtained. It was also evaluated how the velocity fluctuation in the log-region is affected by the coherent structures.

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The three-dimensional flow structure induced by normal shock wave/turbulent boundary-layer interaction in a constant area rectangular duct is investigated by a laser-induced fluorescence method. This diagnostic system uses an argon-ion laser as a light source, and the target gas is dry nitrogen with iodine seeded as a fluorescence material.The Mach number distributions in the duct are obtained from the measured fluorescence intensity, and the three-dimensional flow pattern in the expansion region downstream of the initial shock wave is clarified. In addition to this, the region having locally higher Mach number at the duct corners is observed just behind the shock wave, and the three-dimensional shape of the boundary layers induced by the shock wave is found. These flow characteristics are explained with the simple flow model constructed by considering the interaction between two bifurcated shock waves developed on the two perpendicularly adjacent walls.

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A neural network model of spatiotemporal visual processing can be applied to detect discontinuities in a numerical solution of a supersonic flow. In this paper, the model is developed in efficiency and applied to various types of flow fields. In this paper, it is shown that the Gaussian function, which is used in the original model, can be replaced by the simplest linear function without loss of performance. The present model has been tested using various types of numerical solutions of 2-D and 3-D Euler and Navier-Stokes flows. It is demonstrated that the present model can detect shock waves in the flow field clearly.

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Some calculation schemes of spatial gradient for the spatio-temporal derivative method, which was used for sub-pixel displacement detection in PIV measurements, were evaluated. It was found that the second-order central finite difference scheme tends to underestimate the gradient of tracer-particle's intensity, so that it leads to overestimation of sub-pixel displacements. In this study, a combined upstream and downstream finite difference scheme was proposed and evaluated for one-dimensional flow measurements. Furthermore, the proposed scheme was modified for two-dimensional flow. Two important things for small tracer particle PIV images were shown : 1) the direction of the sub-pixel correction should be taken into account, 2) distant pixels should not be used. It was found that the proposed scheme has high accuracy even if images contain some noises.

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The spray characteristics of an impinging jet injector have been investigated experimentally and numerically. The droplet size distribution, the velocity and the mass flux distribution were measured using Phase-Doppler Anemometry (PDA), and approximated to distribution functions in order to obtain the input data for the numerical simulation by KIVA-3 V. The simulation indicated that the effects of turbulent dispersion on the behavior of droplets must be included in the numerical model. The local droplet size distribution is dominated by the turbulence intensity, because small droplets tend to be transported by the drag of surrounding turbulent gas flow, while the trajectories of large ones are almost straight. Computational grid sizes are also important factor because the turbulence intensity strongly depends on the radial width. Simulations with coarse grids resulted in poor predictions, in which the turbulence intensity was overestimated. It is important to choose proper grid sizes with considering the balance of the accuracy and the computational cost.

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The aim of this study is to clarify the streamwise variation of the production terms for the three-dimensional turbulent air jet issuing from a quasi two-dimensional nozzle affected by the additional strain rate caused by the rectangular notch, and to examine the advection transport of the mean flow and the turbulent kinetic energy affected by the inward secondary flow. The Reynolds number based on the nozzle width and the exit mean velocity, was kept constant 13 000 through this experiment. From this experiment, it was revealed that adding the rectangular notch to the two-dimensional jet, the region of |∂U/∂y|≅0 was generated on the rectangular notch axis in the upstream region, therefore the production of turbulent kinetic energy was suppressed there. Furthermore, the turbulent kinetic energy on the y axis was transported toward the jet center region by the turbulent advection term, this is a reason of that the turbulent kinetic energy on the x axis took the maximum value at the section of x/d =45 which is more downstream section compared to that of the two-dimensional jet.

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When pigmented ink is used in an inkjet printer, the first drop sometimes fails to fly after a short intermission. In the precedent paper, it was shown that the misfire phenomenon is concerned with the dispersed particle condensation and cohesion at the ink surface where the dispersion liquid evaporates. In this paper, perturbation method is used to analyze the dynamics of the air-liquid interface on the condition that the liquid is pressurized to move outward. Calculated results show the unexpected characteristics that the most influential parameter is not the viscosity but. the surface tension of ink. To exblain the misfire phenomenon by using these results, the hypothesis is presented that the lateral capillary force is generated by the particles piled up on the ink surface. This force is considered to work as reinforced surface tension, and causes the interference like the misfire in inkjet motion.

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When pigmented ink is used in inkjet printer, the first drop is sometimes failed to fly after a short intermission of one minute or so. At the first time, the cause of this phenomenon was considered as the dispersion liquid evaporation or the dispersed pigment sedimentation. These answers were denied, however, because of their extremely slow rate response. The simulations for the pigment particles diffusion have been studied by using the Neumann type boundary condition for the liquid evaporation from the ink surface. The derived conclusion is that the dispersed particles are rapidly condensed and packed on the air-liquid interface on a certain condition. It is supposed that the thin film formed on the liquid surface affects the inkjet dynamics, and the misfire is induced.

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The flow velocioy inside the hydrocyclone is measured by LDV (Laser Doppler Velocimeter) for the conventional hydrocyclone and the cyclone with an inner perforated cylinder. Two types of the perforation are used, i.e., low porosity and high porosity cylinders. It is found that the tangential velocity in the hydrocyclone with the perforated inner cylinder behaves like a forced vortex near the central part of the hydrocyclone and like quasi-free vortex outside the forced vortex. The flow inside the conventional hydrocyclone has a high upstream and a large tangential velocity in the region next to the inner air core and the forced and quasi-free vortices follow outside this region.

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Inception patterns of rotating stall in a low-speed axial-flow fan have been investigated by measuring pressure and velocity fluctuations. These experimental measurements were carried out at two different stagger-angle settings for the rotor blades. They show that at the design stagger angle, a short length-scale stall cell known as a “spike” appears first. This stall cell then grows into a long length-scale stall cell as flow rate decreases. At the small stagger angle, a long length-scale disturbance known as a “modal” is first observed, and the modal and the spikes then induce the long length-scale stall cell. The short length-scale stall cell and the modal are first observed at the rotor tip, because the end-wall blockage at the tip becomes large. At the small stagger angle, this blockage is smaller than that at the design angle. The modal is therefore generated before the short length-scale cells appear. It is concluded from these results that the rotating stall-inception patterns depend on the rotor stagger angle.

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The pumping characteristics and the internal flow structure of an inscribed trochoid gear pump are investigated by means of three-dimensional numerical simulation. Cartesian grid system is employed to calculate the fluid flow while the boundary conditions on rigidly rotating gear surface is expressed with Lagrangian markers. The results reveal that the flow rate and the pressure rise obtained by the pump become the highest at Re=10 when the clearance between the two gears is considered. At lower Re numbers, the shear stress transfer on the gear surface fluctuates significantly resulting into lower performance. For higher Re numbers, backward induced jet flow through the clearance makes the internal flow complicated due to non-uniform centrifugal acceleration.

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Quenching experiments on the transient film boiling heat transfer from a vertical cylinder to a quiescent saturated water at atmospheric pressure have been carried out for 18 kinds of silver cylinder which are 8 to 100 mm in diameter and 8 to 160 mm in length. The experimental data obtained by quenching method were compared in terms of boiling curve with the semi-empirical prediction method proposed by the authors. The experimental data agreed within ±15% with the prediction. The effect of aspect ratio (length-to-diameter ratio) on the lower limit of film boiling for saturated water was also discussed and its prediction method was proposed.

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This paper presents a new experiment-simulation combined method that can estimate the critical power of boiling water reactors, BWRs, regarding to spacer geometry. Current experimental method for estimating critical power for BWRs design, require many trained experts and much expensive flow facilities to conduct the experiments. In the present method, a measurement of liquid film flow rate of adiabatic gas-liquid two-phase flow and a subchannel analysis of actual BWRs flow condition are conducted in experimentally and analytically, coincidently. In the experiment, deposition enhancement coefficients of three spacer geometies, a ferrule, an egg-crate, and a ferrule spacer with twisted tape (CYCLONE spacer) were estimated by measuring liquid film flow rate of air-water two-phase flow flowing up in a vertical square (4×4) rod bundle that simulated BWRs 8×8 rod bundle.Using these coefficients, critical powers under each spacer geometry condition were calculated in the subchannel analysis. A validation of this method was conducted using previous data of critical power in actual BWRs flow condition. The critical powers predicted by this method agreed well with those of the experimental data. The result confirmed the effectiveness of this experiment-simulation combined method as well as the advantage over current experimental method in human and facility costs.

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Experiments were conducted to study the flow and heat transfer characteristics of a natural circulation cooling system for electronic components. The test loop consisted of a horizontal test section, a horizontal evaporator, a vertical tube, a horizontal condenser, a rubber bag attached at the exit of condenser, a downcomer, a mass flow meter, and a liquid cooler. The loop height H was set at 250 and 450 mm. In the test section, a silicon chip with dimensions of 10×10×0.5 mm³ was attached at the bottom of a horizontal duct with dimensions of 10×14 mm².A smooth chip and five chips with square micro-pin-fins were tested. For each H, the average flow rate of FC-72 was correlated well as a function of the static head difference between the two vertical tubes. The heat transfer results were compared with those for pool boiling.All chips showed the boiling curve similar to the case of pool boiling except that the critical heat flux was about 20% lower than that for pool boiling.

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A new dynamic simulation program for predicting the precise transient behavior of absorption chiller cycles has been developed. This program has an object-oriented program structure for treating a chiller with an arbitrary structure. A new float box model with high accuracy was devised for calculating the flow rate in a solution circulation line. The simulated results on pseudo-fault situations in a solution-circulation line of an absorption chiller sufficiently agree with the measured transient behavior of an actual machine under the same pseudo-fault conditions. This agreement means that the developed simulation program is an effective tool for developing a precise diagnostic algorithm for various types of absorption chillers.

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Multiple jets are often used to obtain high heat transfer in wide area. Heat and flow behaviour of multiple jets show more complicate characteristics due to the existence of the interactions between adjoining jets, and between jets and spent flows. To clarify the influence of the flow behavior on heat transfer fields, the time and spatial heat transfer coefficients over the impingement plate were measured using an infrared radiometer when four jets impinged to the impingement plate for various jets arrangement and separating distance from jet exit to the impingment plate. The flow fields were also visualized by means of a water table. The heat transfer characteristics is made clear from the results of the instantaneous heat transfer contour or temperature fluctuation values.

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A numerical analysis was made on natural convection from a downward-facing heated plate. Basic equations for mass, momentum and energy were discretized by finite difference method and numerically solved by the HSMAC method. The computation domain with many grids was arranged to allow for the edge effect of the plate and its suitable size was decided from the viewpoint of better agreement with experimental results. The numerical solutions of fluid flow and thermal fields were obtained and their characteristics were investigated in terms of Rayleigh number. Correlations of Nusselt number were compared with experimental and numerical results.

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Numerical results simulating a three-dimensional separated flow and heat transfer around surface-mounted rectangular blocks in a plane channel are presented. Flow configuration treated in the present study is transversal two blocks. The finite difference method is employed to directly solve Navier-Stokes, continuity and energy equations, and resulting finite difference equations are solved with the SMAC method in Reynolds number range from 100 to 500. Present results are compared with available flow visualization ones and it is found that the present numerical method well simulates the observed results such as horseshoe vortices and the recirculating separated flow. Local and mean heat transfer characteristics are clarified and their correlations with the flow structure are investigated.

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Direct numerical simulation methodology is employed to analyze the unsteady characteristics of a two-dimensional separated and reattached flow and heat transfer around an inclined downward step in a plane channel. Numerical calculations of the Navier-Stokes, energy and continuity equations are carried out using the finite difference method. The Reynolds number Re based on the mean velocity at inlet and the step height ranges from 300 to 2 000, and the inclination angle of step α is systematically varied from 15° to 90°. The expansion ratio of channel is 2.0. For all the inclination angles examined, the flow is steady at Re≤500 but becomes unsteady at Re=700. In a range of α from 30° to 75°, effects of α upon the reattachment length and the maximum Nusselt number are relatively small in a wide range of the Reynolds number.

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Flow and heat/mass transfer characteristics for turbulent flow in serpentine channels with an inclined partition wall have been examined experimentally. Detailed velocity distributions have been measured using Particle Image Velocimetry for three kinds of partition wall's inclination angle with respect to the outer walls (α=+4°, 0°, -4°) at Reynolds number of 3.5×10⁴. The PIV measurements results were compared with the published local mass transfer results for these three cases, and the mechanism of the heat (mass) transfer from the channel wall after turn section were discussed. Based on these data, the inclination angle can bring significant changes to the fluid characteristics and local heat (mess) transfer characteristics. The heat (mass) transfer enhancement after turn is controlled by the value of secondary flow velocity, convective mean velocity, turbulent kinetic energy, and their contribution rates are remarkably changed by the channel configurations.

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Experimental study on heat transfer and fluid flow has been carried out for a swirling impinging round jet. Thermochromic liquid crystal sheet was used for the heat transfer measurements and the three velocity components were measured in the stagnation region with LDV for the cases of the swirl number Sw =0.0, 0.22 and 0.45 at a Reynolds number Re=8100. The formation of recirculation flow near the wall due to the swirl is found to decrease the heat transfer coefficient in the stagnation region and results in a more uniform distribution of Nusselt number with increasing the swirl number. Heat transfer mechanism of a swirling impinging jet is discussed based on the flow characteristics of the mean velocities and turbulent quantities.

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LIF thermometry in a sooting diffusion flame was newly proposed based on a spectral matching method. A tunable ArF excimer laser was used to excite the several absorption lines in the D²Σ⁺←X²II (0, 1) band system of NO. In the case of sooting diffusion flame, emission spectrum consisted of NO and O₂ fluorescence, and off-resonance emissions related to the soot. The O₂ fluorescence and the off-resonance emissions overlapped on the NO fluorescence. However, the off-resonance emissions near the vacuum ultraviolet region (VUV) were weaker than the NO fluorescence, and theε (0, 3) band of the NO fluorescence, which appeared near the VUV region, was free from the O₂ fluorescence. Therefore, NO rotational temperature in a sooting diffusion flame could be measured by the spectral matching method using the ε (0, 3) band. By using this technique, NO rotational temperature in a propane diffusion flame could be measured.

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Effects of DC electric fields on combustion of droplet pairs were investigated experimentally under Microgravity condition. Fiber-supported n-octane droplets with initial diameters of about 0.7 mm were studied in air at normal atmospheric conditions, with electric field intensities up to 55kV/m. Flames around single droplets are elongated mainly towards the negative electrode, and soot particles are emitted towards both electrodes but mostly towards the negative electrode. Droplet pairs with merged flames were found to behave similarly, but with separated flames the droplet nearest the negative electrode appears to experience electric wind, while the droplet nearest the positive electrode does not. The electric wind appears to increase the burning rate of the droplet.

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Thermal barrier coatings and functionally graded materials (FGM) have been applied to a turbine blade exposed to high temperatures. Therefore, the evaluation of thermophysical properties of these coating materials is very important for designing turbine blade. We have adopted the photothermal radiometry (PTR) for the measurement of thermophysical properties of FGM at high temperatures. In this method, a layered sample is periodically heated by a modulated light source and periodic temperature variation is caused on the sample. The phase-lag between the modulated light source and the temperature variation on the sample contains information of thermal properties of the sample. We have measured the thermal diffusivity and thermal conductivity of round-robin FGM (single layer) at room temperature and compared the present results with other data obtained by the laser flash method. The average deviation of the other data from the present results was 14% both for thermal diffusivity and the thermal conductivity. We have measured the thermal diffusivity and thermal conductivity of FGM in the temperature range up to 1 273 K.

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A modeling of a coal gasification reaction and prediction of gasification performance of an entrained flow coal gasifier are presented in this paper. The purposes of this study are to develop an evaluation technique for a design and performance optimization of the coal gasifier using a numerical simulation technique and to confirm the validity of the model. The coal gasification model suggested in this paper is composed by a pyrolysis model, char gasification model and gas phase reaction model. A numerical simulation with the coal gasification model was carried out on the CRIEPI 2 tons/day bench scale coal gasifier. Influence of air ratio on gasification performance, such as a per pass carbon conversion efficiency, amount of the product char, a heating value of the product gas and cold gas efficiency, is presented on the 2 t/d coal gasifier. Gas temperature distribution and product gas composition are also presented. Comparison between the computation and the experimental data shows that most features of the gasification performance have been captured accurately by the numerical procedure and the validity of the current model was confirmed.

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Unsteady state heat transfer and reaction characteristics were analytically investigated by means of the two-dimensional unsteady analytical model, including the effects of the heat transfer between particles and fluids in this paper. It was clarified that the key factor in whole system was the heat transfer on the wall. Investigating the effects of the controlling factors on the transient heat transfer and reaction in the reforming catalyst bed, such as velocity and wall temperature against the experimental results, an advantage in a result was shown by the proposed analytical model with an optimization of the effective thermal conductivity.

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Study of a curing process of rubber has been conducted. Two kinds of rubbers, vulcanized and compounded SBR rubbers, were tested. The rubber was packed in a cylindrical container of inner diameter 74.6 mm. The container was controlled at a uniform, constant temperature, ranging from 403 to 433 K, and radial distributions of the temperature and cure state during the process were measured. For the two cases, typical temperature fields for unsteady, one-dimensional heat conduction problems were observed. However, the uniform temperature field was formed faster for the compounded rubber than for the vulcanized one. At the terminal period of the curing process, a slight temperature decrease toward the container wall was also observed in the rubber, and this implies the existence of the heat flow toward the container wall. These phenomena may be due to the influences of the reaction heat. Previous chemical reaction model of the cure state was compared with the present data, and good agreements were obtained. This conclusive result brings better understandings for the practical production problems.

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Emulsified Biodiesel has lower NOx and Smoke emissions compared with Biodiesel. In this study, a new emulsified Biodiesel with 15 wt% water is made without adding any emulsifier, and the combustion characteristics and exhaust emissions for the new fuel are investigated using a DI diesel engine. The new fuel has shorter ignition delay and lower CO, HC, Smoke and Aclorein emissions compared with the 15 wt% water emulsified Biodiesel with adding 0.1 wt% crude glycerin as an emulsifier. Moreover, the effect of the crude glycerin content on emulsified Biodiesel combustion is investigated. The emulsified Biodiesel has larger water droplet size and lower viscosity with decreasing crude glycerin content, and as the result, the ignition delay becomes shorter, and the HC, CO, Smoke and Aclorein emissions become lower.

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In order to widen the operational range of a dual fuel engine and maintain good thermal efficiency and emission characteristics, ozone was added into the suction air. Experimental results showed that the added ozone improved the ignition performance of the engine ; eventually homogeneous charge compression ignition (HCCI), with only natural gas/air premixture and no fuel injection became possible under 1 300 ppm or higher ozone concentration without any extra devices such as an inlet air heater. Numerical analysis simulating the compression to ignition stage also supports this phenomenon mainly based on release of active 0 radical decomposed from ozone.

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The temperature and thermal strain were examined on the fire surface of the gray cast iron cylinder head. The measurements were carried out by thermo-couple and strain gage during high temperature and high pressure in operating condition. The mechanism generating the strain on the fire surface of the cylinder head in the operating condition was made clear using experimental data and some numerical analyses. The considrations on regard to the temperature distribution and the stiffness distribution of the cylinder head etc. were very important for understanding this mechanism. And also, the calculated results were in good agreement to the measured temperature and strain. The evaluation of the fatigue safety life for the thermal strain was discussed, including the material properties and the operating condition in the fishing boat.The prediction of the reliability would be possible to perform in the design stage of the cylinder head.

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