Fully developed turbulent reacting jet formed by introducing inlet condition given by a turbulent channel flow was analyzed by the data base fo direct numerical simulation. We show that characteristic vortex structure exist in fully developed turbulent jet. Spanwize vortices exist in high-shear region and streamwise vortices bridge gaps between spanwize vortices. Detailed interpretation has been made to elucidate the interactions between vortex distribution, where streamwise and spanwize vorticities interact. Streamwise vorticity becomes large where spanwize vorticity is large, which indicate that rotation of spanwize vortices stretch streamwise ones.

抄録全体を表示

In this paper the author discussed the Bio-energy aspect from the forest resources and forestry. First the characteristics of the wood fuel as the bio-energy are defined and second the relationship between energy supply amount and fuel price are denoted. Third the utilization types of wood fuel in Japan and foreign countries are summarized. Fourth the amount and distribution of wood fuel are estimated in case of Kyushu Island. And fifth the problems are denoted in the utilization of wood fuel in Japan. For developing the utilization of Bio-energy, especially wood fuel in Japan, many people and researchers are needed to participate to this project.

抄録全体を表示

Experiments of the "semi-carbonization" pyrolysis were conducted for cellulose : the main component of woody biomass, citric acid and their mixtures in order to clarify the optimal pyrolysis condition and the effect of acid additives on the semi-carbonization. The acid additive promoted dehydration of woody biomass, and affected the weight yield of char within the temperature region of the semi carbonization. The analytical model to evaluate the energy value of the semi-carbonized fuel was presented based on the reduction in the value due to the transportation. The optimal pyrolysis condition of the semi-carbonized fuel was clarified for the dimensionless distance of the transportation. It was found that the acid additives contributed to saving the energy consumption of the "semi-carbonization" pyrolysis process and improving the transportation.

抄録全体を表示

Combustion processes contain chemical reactions with heat release and hydrodynamic instability. Especially, solid combustion is much more complicated than gas combustion. Therefore, the physico-chemical mechanism has not been clarified fully. More recently, there have been a few investigations on thin solid fuels without flame. The biomass fuel which is energy which I can revitalize for fossil fuel attracts attention. We think that solid fuel including biomass fuel gives a combustion form bug influence because heterogeneousness is strong. In the present study, we used a biomaterial sheet of wood system as fuel and examined the influence that heterogeneousness of fuel gave a combustion form.

抄録全体を表示

From a viewpoint of environmental preservation and resource protection, the recycling of wastes has been promoting. Expectations to new energy resource are growing by decrease of fossil fuel. Biomass is one of new energies with prevent global warming. This study is an attempt to burn pelletized woody biomass (Bio-pellet) made from sawdust and logging residue in order to thermally recycle waste products of forestry and lumbering industry. Fundamental data on Bio-pellet combustion were obtained in an electric furnace. Combustion appearance, weight and temperature of pellets were investigated under specified furnace temperatures and sizes to obtain combustion characteristics such as ignition delay, burning period, char-combustion time and the change of weight decrease and temperature rise.

抄録全体を表示

The purpose of the present research and development is to develop technology for converting biomass resources into energy economically and with high ecciciency-specifically, technology for co-firing of woody biomass and coal at existing coal-fired power plants, which currently have high CO_2 emission rates.

抄録全体を表示

Fundamentals of pyrolysis and combustion characteristics of several types of biomass were studied, using a thermogravimetric analyzer. In order to elucidate effect of the biomass addition on coal combustion behavior, combustion performance, NOx emission characteristics and ash formation were discussed, using an electrically heated drop tube furnace. The results obtained showed that pyrolysis and combustion characteristics of biomass depended on lignin and cellulose composition in the biomass. The biomass could enhance the ignition of the low-rank coal. However, NO and N_2O emission behaviors under the co-combustion condition resembled those under the coal combustion. When the biomass was burned alone, fine particulates of less than 2,, m are produced. Under the co-combustion condition, coal ash could capture the fine particulates from the biomass during combustion.

抄録全体を表示

Woody biomass, especially forest biomass has a big possibility as a carbon neutral new energy. There are various methods to transform woody biomass into energy. It is said that the gasification power generation is advantageous in Japan where dispersed small-scale power generations are suitable. Thereinafter we would like to explain the procedure of the gasification such as direct gasification and indirect gasification. And also we are pleased to introduce our demonstration test facility of the gasification power generation of indirect gasification method which we, including I myself, were engaged in Yamaguchi Pref. We will continue to pursue the future possibility of woody biomass energy more and more.

抄録全体を表示

The particle conversion during gasification of petroleum cokes in CO_2 gas was examined using a thermogravimetry analyzer and a captive particle imaging apparatus. The conversion of gasification of petroleum cokes was influenced by a temperature of environment. Using a petroleum coke was addel 1∿10wt%-K_2CO_3 as a catalysis of gasification, the relationship between the value of added catalysis and the kinetics of the gasification order of petroleum cokes was acquired. The petroleum coke added 3∿10wt%-K_2CO_3 was improved the kinetics of gasification order.

抄録全体を表示

In this paper, two experiments on the effect of steam injection into the reformer or into the pyrolyzer have been carried out respectively using wood chips as feedstock, by a micro-scale gasification system for solid wastes known as the STAR-MEET system. The results showed that the combustible gases generated in the reformer, especially H_2 and CO obviously increased when injecting steam directly into the pyrolyzer. It was also shown that the produced refermed gas was usable for power generation using the dual-fueled engine.

抄録全体を表示

A distributed type small-scall gasification and power generation system using solid wastes is developed. In this system, tar and soot components in the pyrolysis gas produced from a pyrolizer is reformed into gaseous components decomposed by using steam and air or oxygen in a reformer. The reformed gas is introduced into an internal combustion diesel engine as a fuel gas for power generation. In this research, experimental result on gasification and power generation using woody biomass as a fuel have been performed for the purpose of increasing the amount of fuel processing capacity, calorific value of the generated fuel gas, and the energy conversion efficiency.

抄録全体を表示

To understand the behavior of the down-flow gasifier for woody biomass, the optimum operation conditions and gasification characteristics were studied. Pulverized wood powder sieved under the 60 mesh was used for gasification fuel in this paper. The CO_2 concentration was increased 10% by the oxidation reaction with increasing the temperature 200 K at the temperature of 1600K. However, total production of CO and H_2 were moderate change and it was around 60%, 40% for CO and 20% for H_2 in the total flue gas. CH_4,C_2H_2 and C_2H_4 were under 5%, 2%, 2%, respectively at the same condition. Therefore, combustible gas (CO+H_2+CH_4) was over 60% and the gas-heating value was 5.9-8.9 MJ/m^3N. Carbon gasification conversion and cold gas efficiency achieved 90% and 50% respectively at the temperature of 1600K. Choking trouble by biomass tar at the bag filter was controlled better by injecting inert absorbent.

抄録全体を表示

The group combustion behaviour in a premixed spray was observed in detail by simultaneous optical diagnostics. Mie scattering images of droplets illuminated by a laser light sheet were obtained in time series by a high-speed camera. In addition, at a particular point in the target region of the images, time-series signals of the light emission in OH and CH bands, and the Mie scattering from droplets was detected by a specially designed receiving optics, Multi-color Integrated Receiving Optics (MICRO), and the size and velocity of droplets with a phase Doppler anemometer (PDA) were monitored, simultaneously. The high data rate and high validation rate of PDA measurement accomplished by the optimized design of PDA optics enabled us to distinguish instantaneous characteristics of individual droplet clusters in the flame. Thus, we estimated the group combustion number G_C for individual droplet clusters using the measured mean separation distance between droplet centers and the total number of droplets in each droplet cluster.

抄録全体を表示

Droplet combustion experiments have been performed in microgravity as fundamental researches on spray combustion. Relatively large droplets (about 1mm) were used in order to obtain high resolutions in time and space although fine droplets burns in real spray combustors. In the present paper, scale effects in droplet and spray combustion were discussed. Under diffusion-controlled conditions, the phenomena for different initial droplet diameter are similar to each other. Deteriorations of the similarity are found in ignition and microexplosion of fine droplets and in droplet-flow interaction.

抄録全体を表示

A homogeneous spray burner was developed to perform fundamental study on partially-prevaporized spray combustion. Laminar stream of homogeneous spray was generated by the condensation method using rapid expansion of saturated ethanol vapor-air mixtures. Microgravity condensations were employed to prevent large fuel droplets from falling down. Flat flame of homogeneous fuel sprays was stabilized successfully between a nozzle exit of the burner and a stagnation plate under normal and microgravity conditions. Very thick flames were observed for spray streams which include large fuel droplets. It was found that burning velocity of homogeneous spray is larger than that of premixtures of the same total equivalence ratio in stretched flow fields.

抄録全体を表示

A series of microgravity experiments were performed in order to investigate flame propagation process of a n-Decane linear droplet array. In the experiments, direct images of the flame and hydroxyl [OH] radical self-emission intensity distributions on projection plane were observed and recorded. The obtained images show detailed flame propagation along a linear droplet array and around the each droplet. Also, they describe the switching process from premixed combustion of evaporated fuel to diffusive flame style around he droplet.

抄録全体を表示

Numerical calculation on flame propagation of a linear fuel droplet array was conducted with focusing on effect of pre-evaporation of droplets. The calculations considered flame propagation of n-decane droplet array in ambient air. In these calculations, pre-evaporation of droplets had been promoted before heat source for ignition was set next to an edge droplet. Some calculations were conducted with different degree of pre-evaporation by changing the time when ignition heat source was set at. Interesting structure like triple flame was observed in propagating flame. Also, flame propagation rate V_f significantly increased when flammable gas layer around each droplet was combined. In addition, increase of V_f was also observed by microgravity experiments.

抄録全体を表示

For the purpose of exploring the fundamental phenomenon of spray turbulent combustion, this research aims to investigate interactions between droplet flames and vortex tubes composing coherent structure of turbulence using a model based on a droplet flame in varying forced convection. A fuel droplet is placed at the focusing point of the swinging forced convection apparatus installed in a high-pressure combustion chamber. An analogy between the interaction and the model was discussed in order to determine the experimental condition. Experimental apparatus for microgravity experiment was developed and tested using MGLAB dropshaft, finding a response of instantaneous burning rate constant to the varying flow.

抄録全体を表示

A three-dimensional numerical simulation is applied to a pulverized coal combustion field in a test furnace equipped with an advanced low-NOx burner called CI-α burner, and the detailed pulverized coal combustion characteristics are investigated. The numerical results are in general agreement with the measurements, and verifies that a recirculation flow is formed in the high-gas-temperature region near the CI-α burner outlet, and this lengthens the residence time of coal particles in this high-temperature region, promotes the evolution of volatile matter and the progress of char reaction, and produces an extremely low-O_2 region for effective NO reduction. The effect of the recirculation flow on the particle residence time is significant for the small particles with diameters less than 40μm. Regarding No emission mode, the efficiency factor of the conversion of char N to NO affects the total NO concentration in the downstream region after the injection of staged combustion air.

抄録全体を表示

The coal-pyrolysis experiment in high pressure conditions using a pressurized thermobalance has been carried out to clarify the mechanisms and processes at conditions changing from normal pressure to higher pressure (10.6ata). Simultaneously, a new pyrolysis model which can describe a pressure effect on the evolution behavior has been developed based on the FLASHCHAIN^[○!R]model including a quantitative estimation of the volatilized gases and released tar vapor. From the experiment, the gas yields of CH_4 and CO show increasing behavior at higher pressure conditions (Ar). At higher pressure condition the the tar vapor formation is suppressed, then the recombination reactions of remainning metaplast are activated, resulting in more intermediate chars and more gas formations. It is also found that the effect of oxygen concentration on the reaction rate in low temperature range is stronger than that in high temperature range.

抄録全体を表示

A direct numerical simulation (DNS) is applied to a particle-laden turbulent mixing layer with a chemical reaction, and the effects of particles on turbulence and chemical species' diffusion and reaction are investigated. The unreactive particles, whose response time, τ_P, is smaller than the Kolmogorov time scale, τ_K, [τ_P/τ_K=O(10-1)], are uniformly injected into the high-speed side of the mixing layer. Two reactive chemical species are separately introduced through different sides. The results show that although laden particles generally depress the streamwise and transverse turbulent intensities and mean squared value of concentration fluctuation on the central interface in the mixing layer, they begin to enhance them downstream as the particle size decreases provided the inlet particle volume fraction is fixed. Also, since the small-scale turbulence in the coherent vortices, which promotes the chemical reaction, are suppressed by the laden particles in he whole region, chemical product decreases overall.

抄録全体を表示

On the spray combustion, Eulerian-Langrangian method is well known as accurate method and adopted to various problems in many previous papers. But most of these don't solve gaseous phase directly, or contain physical uncertainness in pressure field. Forthermore, interaction between gaseous phase and liquid droplet mainly depend on experimental equations. In this paper, we adopted new numerical method to compressive reactive flow, and tried to construct more accurate simulation method for multiphase combustion. We performed two types of simulation, one is well known Eulerian-Lagrangian method, which gaseous phase is solved directly, and the other is interface tracking method.

抄録全体を表示

High temperature air combustion technology (HiCOT) has demonstrated high effectiveness in significantly enhancing the performance of industrial furnaces, achieving advantages such as energy savings, CO2 reduction and reduced emission of NOx for gaseous fuels. This technology is expected to be applicable not only for gaseous fuels but also for solid fuels like pulverized coal, with the same advantages. To ascertain the advantages, the combustion behavior of pulverized coal in high temperature air using various coal combustion furnaces have been studied. As the results, we can ascertain the advantages of HiCOT applied to pulverized coal combustion, low NOx emission and stabilized combustion of low volatile coal.

抄録全体を表示

We examined the applicability of a coal combustion model to commercial boilers. The coal combustion model, which has char and NOx reaction models, has been developed on the basis of experimental data obtained by using a drop tube furnace (coal feed rate : 0.6kg/h). We applied the coal combustion model to the simulation from a laboratory scale furnace (coal feed rate 25kg/h) to commercial boilers (coal feed rates : 100 to 300t/h). 1) The model was applicable to any size furnaces. 2) Reduction reactions by hydrocarbon radicals were important to predict NOx concentration. 3) The predicted furnace exit gas temperatures were in agreement with the measured ones with less than 30℃.

抄録全体を表示

In this paper, sensing techniques for the thermofluid engineering are traced to the nonintrusive and multidimensional one of late date. Several techniques for measurement of thermodynamics variables in gaseous flows using the laser, such as laser-induced fluorescence (LIF), Coherent Anti-Stokes Raman Scattering (CARS), Degenerate Four Wave Mixing (DFWM) and so on, are tabulated for comparison. Finally, Resonantly Enhanced Multi-Photon Ionization (REMPI) and Pressure Sensitive Paint (PSP) are introduced as candidates of the molecular sensor for the high Knudsen number flows with the long mean free path or the short characteristic length.

抄録全体を表示

The pressure sensitive paint (PSP) technique has the capability to be applied to high Knudsen number flows, such as low density gas flows, micro-flows, and so on. In this study, to inspect the feasibility of PSP for measurement of pressure on a solid surface in the high Knudsen number flows, fundamental properties of three types of PSP [PdTFPP, PdOEP and PtTFPP bound by poly (TMSP)] are examined especially in the range of pressure below 130Pa (about 1 Torr). The pressure sensitivity against nitrogen monoxide is also examined for the above PSPs, to develop a technique for the composite measurement of the flow field structure and the surface pressure, using NOLIF and PSP, respectively. As an application of PSP to low density gas flows, we measure the pressure distribution on a jet-impinging solid surface using PdOEP/poly (TMSP) with very high pressure sensitivity.

抄録全体を表示

The aim of the present work is to demonstrate the feasibility of a porous pressure-sensitive paint (PSP) for time-resolved surface pressure measurements in unsteady high-speed flows. The porous PSP was composed of bathophenanthroline ruthenium (II) complex, Ru((Ph)_2-phen), and a silica-gel thin-layer chromatography (TLC) aluminum plate. The porous PSP was applied to the surface pressure distribution imaging of an unsteady flow in a two-dimensional Laval nozzle with a fast-framing complementary metal oxide semiconductor (CMOS) camera. The result clearly shows that the combination of the porous PSP and the CMOS camera well captured high-frequency shock-wave motion on the order of kilohertz in the nozzle.

抄録全体を表示

As material changes during the production or reaction processes, its thermal properties are expected to change with time. However, it is seldom conducted to take into account the properties variation for thermal design. We have developed the forced Rayleigh scattering method (FRSM) to apply the highspeed and real-time measurement of the thermal diffusivity of changing material. In the present study, theoretical considerations of measurement repetition interval and error analysis of property evaluation during one measurement are conducted. Continual measurement of sol-gel transition process of biopolymer has been carried out, and dynamical change of thermal diffusivity at the gelation point has been detected. The results illustrate the validity of FRSM to real-time thermal diffusivity monitoring technique of rapid process.

抄録全体を表示

An aerospike nozzle has been expected as a candidate for an engine of a reusable space shuttle to respond to growing demand for rocket-launching and its cost reduction. In this study, the flow field structures in any cross sections around the linear-spike nozzle are visualized and analyzed, using laser induced fluorescence (LIF) of NO seeded in the carrier gas N_2. Since the flow field structure is affected mainly by pressure ratio (P_s/P_a), the liner aerospike nozzle is set inside the vacuum chamber to carry out the experiments in the wide range of pressure ratios from 75 to 250. Flow fields are visualized in several cross-sections, demonstrating the complicated three-dimensional flow field structures. Pressure sensitive paint (PSP) of PtTFPP bound by poly (TMSP) is also applied successfully to measurement of the complicated pressure distribution on the nozzle surface.

抄録全体を表示

In CO_2 ocean sequestration, dilution process of injected CO_2 past a releasing pipe is of great importance to predict biological impact. Highly turbulent flow past the releasing pipe at supercritical Reynolds number plays an important roll for enhancement of CO_2 dilution. In this study, we investigated the highly turbulent flow field past a circular cylinder by using time-series particle image velocimetry (PIV). We measured two-dimensional velocity field and its turbulent properties such as mean velocity, turbulent intensity, and Reynolds shear stress at supercritical Reynolds number.

抄録全体を表示

Characteristics of turbulent boundary layer flows with adverse pressure gradients (APG) differ significantly from those of canonical boundary layers. We have investigated the effects of APG on the higher-order moments and spectra of velocity and temperature fluctuations in a thermal boundary layer developing on the uniformly heated plate. It is found that, in the APG boundary layer, the momentum and heat transfers occur in the direction toward the wall from the region away from the wall. The structural change in APG flow causes the non-local interactions between the temperature fluctuations and the wall-normal motions. However, the situation is fairly complex because the heat transport is mainly determined by the ejection motions, which are not significant contributors to the momentum transport in the APG flow.

抄録全体を表示

Unsteady heat transfer from a circular cylinder to the cross-flow of air was investigated experimentally for Reynolds numbers from 3000 to 15000,in the range for which the Nusselt number in the separated flow region increases sharply with increasing the Reynolds number. The present investigations indicated that the alternating rolling-up of the shear layers that have separated from the cylinder reaches to the rear face of the cylinder at Re>5000 due to the forward movement of the vortex formation region. This leads to an initiation of the alternating reattached flow on the rear face of the cylinder, interlocked by the vortex shedding.

抄録全体を表示

In micro-channel flow without/with backward and forward facing step, the effects of the flow and heat transfer with the mixture of multi-size particles are investigated by new image processing for the control of the flow and heat transfer field. In the area of micro-size, it is not easy to control the heat transfer with increasing and decreasing locally by devices and external forces but it is possible to perform using non-direct phenomena with the mixture of multi-size particles in the flow. Because of the velocity distribution at each area of flow field, the tracking line of multi-size particles may be different from the drag effects of the each body size. Then, the velocity distribution would be changed more emphasized by big-sized particles and passing by mid-sized particles to get new heat transfer field. It would be needed three kind of particle size at least to perform and detect the phenomena The characteristic choices of the particles with size and material are very important for getting the deigned heat transfer field. For the purpose of making clear the effects of multi-size particles mixture, it is need to develop new image processing methods including the detection the area of the occupied particle and the discrimination of the particle size. In this paper, the methods and results above are reported and discussed for the detection and evolution the effects of the mixture with multi-size particles with tentative flow configuration as early trial research stage. From the results, several qualitative interesting effects were given with the continuous pictures and immature image analysis, and the quantitative results would be got and reported after the building and confirming the new image processing methods.

抄録全体を表示

This paper shows how heat transfer enhancement is improved by the reattachment air flow contained a little mist. Vaporization of mist caused by differences of absolute humidity between upstream and reattachment regions makes heat transfer downstream from step increase rapidly, when the shear layer of dividing stream line being separated from upstream step absorbed a little mist at upstream point and then reattached near the wall surface downstream. This method is attracted in heat transfer enhancement for the heat transfer coefficient is rapidly increased and simple supplying water unit only set up to the heat exchanger.

抄録全体を表示

Instantaneous two-dimensional flame structure in turbulent propane-air premixed flames is studied using OH-PLIF (Planer Laser Induced Fluorescence). Turbulence is generated by performed plate. A lean mixture (equivalence ratio : φ=0.60∿0.75) of 175cm/s averaged velocity is selected for experimental condition. Turbulence intensity is about 17cm/s, classified in wrinkled flamelet regime on the Regime diagram. Instantaneous 2-D OH image is visualized to make clear the flame front and OH structure. Results show that cusps on the flame front appeared. As equivalence ratio increases, OH peak distance is larger with the increase the flame front curvature.

抄録全体を表示

Turbulence structures of a diffusion flame formed in a backward facing step flow have been experimentally investigated. Two-point correlation analysis of the temperature field revealed in detail spatiotemporal structures of the flame, and it was shown that a sequence of harmonious behaviors of high- and low-temperature fluid parcels was a key process stabilizing the combustion.

抄録全体を表示

A novel technique is proposed for measuring an instantaneous spatial reaction zone profile of turbulent premixed flames. The technique is realized by combining multi-lens-camera photography with computer tomography. The technique is developed by using a maximum likelihood-expectation maximization (ML-EM) method for CT analysis. Three-dimensional reaction zone profiles of turbulent premixed flames are reconstructed using the proposed technique. It is shown that complex thin reaction zone profiles with flame extinction are successfully reconstructed, indicating extreme usefulness of the proposed technique in studying turbulent flame structure.

抄録全体を表示

Distribution of CH and OH radicals and the 3-component velocity field are measured simultaneously by planar laser induced fluorescence (PLIF) and stereoscopic particle image velocimetry (PIV) in turbulent premixed flame of laboratory scale swirl burner. The measured CH and OH profiles indicate the location of local flame front and its shape, and accompanying 3-component velocity field provide the instantaneous velocity field. The observed scale of wrinkled flame front and flame cusps correspond to integral length scale and Taylor micro scale of unburned mixture, respectively. The interactions between flow field and local flame front were observed by these measurements.

抄録全体を表示

High spatial resolution time-series PIV system, time resolution of which potentially ranges from several hundreds Hz to several tens kHz, has been developed using two high-repetition-rate Nd : YAG lasers for industrial processing and a high-speed CMOS camera. The developed system was applied to a turbulent jet and fluid flow maps with 26.7kHz time-resolution were obtained. In addition, various time-resolution measurements up to 16kHz were conducted to estimate the performance of the developed high spatial resolution time-series PIV system. From the time-series PIV measurement, dynamics of the turbulent structure can be visualized clearly.

抄録全体を表示

We developed a three-dimensional particle velocimetry (stereo-PIV) system with optical fiberscopes to measure fluid motion in such as a closed vessel to which extra windows for flow measurement are hardly attached. The present study proposes a processing technique to match a particle with the auto-correlation fitting function in order to reduce the image degradation by fiberscopes transmitting, in conjunction with particle streak images controlling pulse timing of diode laser in order to increase the reliability of vector processing (PTV-SS method). An axial jet flow was selected to validate the present system, which was also measured by using a laser Doppler velocimetry. A bias error due to the image degradation by fiberscopes transmitting was reduced by 95%, therefore and the present system is expected to obtain the accurate velocity-vector field.

抄録全体を表示

Nozzle flow experiments were carried out in order to investigate low-pressure steam flow characteristics. Two types of nozzle blades, named "A" and "B", which are with or without an inlet large round head respectively were tested to compare nozzle flow characteristics. The experiments were conducted under an inlet total pressure of 0.3MPa, an inlet total temperature of the superheated and saturated, and a pressure ratio of about 1.5. The experimental results show that the mass mean total pressure ratios in nozzle B were a few percent higher and the results of the steam flow visualization with PIV technique show that the droplet flow in nozzle A has a boundary-layer exfoliation on the suction side of a nozzle blade.

抄録全体を表示

A swirling impinging jet results in a more uniform distribution of heat transfer coefficient compared to that of the conventional impinging jet. In this study, the flow structure of the stagnation region near the wall was investigated by 3D-Particle Image Velocimetry(PIV), and PIV measurements were also compared with LDV data. In PIV measurement, in addition to 2 velocity components, we obtained out-of-plane velocity component by overlapping the laser light sheets of two kinds of wavelength and calculating their cross correlation coefficient.

抄録全体を表示

A dynamic PIV technique developed under the support of KAKENHI (14205031,Prof. Hayami at Kyushu University) is applied to a submerged circular impinging jet flow of water at a Reynolds number of 11,600. The complex turbulent flows have been rcsolved at 2kHz with 1024×1024 pixcle with horizontal and vertical cuts of the flow field. It is demonstrated that the time-and space-resolved PIV measurement can provide unprecedentedly large amount of information about turbulent flow fields, the information from which not only the statistical quantitics but also the time evolution of turbulence structures is extracted. The quantitative validity of the measurement is confirmed by the comparison with the data reported previously.

抄録全体を表示

Measurement of dynamic surface deformation (DSD) is important for full understanding of oscillatory mechanisms of Marangoni convection in a liquid bridge. A novel method based on electronic speckle pattern interferometry (ESPI) is developed here. ESPI is widely used for displacement measurement of optically rough surfaces. The present system expands the capability of ESPI so as to measure specular liquid surfaces. Time sequence phase method is adopted for phase evaluation of specklegrams, which enables the method to measure dynamic displacement of deformed liquid surface with sensitivity of λ/4. Frequency analysis and comparison with previous data of DSD of liquid-bridge free surface are presented.

抄録全体を表示

The main purpose of this study is to improve the performance of surface fusing or globular forming, system of thermoplastic fine particle. First, the flow and thermal characteristics and their relation of high temperature air jet from a pipe nozzle were made clear by measuring the mean and fluctuating velocity and temperature profiles. In order to control the jet diffusion in the radius direction the ring nozzle which has ring-shaped contraction near the nozzle exit was used and its flow and thermal characteristics were made clear. Next, the heat transfer rate of necessary for the globular forming of fine particle was examined and clarified.

抄録全体を表示

The flow field through an axisymmetric sudden expansion is measured using two multi-point LDV systems and an azimuthal structure is discussed by correlation of a fluctuation of velocity profile and conditional average, especially make attention to the behavior near wall region. The raw spatio-temporal velocity field between two measuring lines with some azimuthal angle shows a complex one. The contour map of correlation in azimuthal direction - lag time field indicates staggered like structure. The conditional average shows the structure of reattachment phenomenon.

抄録全体を表示

The flow visualization and PIV measurements are carried out for turbulent velocity fields in a T-junction, which models the HVAC unit used in an automobile air conditioning system. The measurements are performed at Reynolds number in the main channel of 2.5×(10)^4 and cross flow velocity ratio ranging from 0.5 to 2. Based on present measured data, the influences of velocity ratio on the flow characteristics after the T-junction are clarified. It has been found that the characteristics of the flow reattachment, the separation bubble and vortex structures at the mixing interface and inside the separation bubble are much influenced by the cross flow velocity ratio.

抄録全体を表示

The present experiment is conducted to examine the evolution of salt-finger convection during unidirectional solidification of NH_4Cl-H_2O system. We perform flow visualization and velocity measurement. The salt-finger convection experiences the dynamical behavior in the early stages of solidification, i.e., the transition of longitudinal motion to lateral motion. The velocity of upward flow is larger than that of downward flow.

抄録全体を表示