This study experimentally investigated flow structure and heat transfer caused by a pair of delta-wing vortex generator in front of tubes. The effects of the attack angle and the distance between the delta-wing and tube on the heat transfer performance for two different configurations of the delta wings were investigated for laminar Reynolds number range. It was found that the heat transfer was enhanced by increasing the attack angle for the inflow configuration of delta-wing pair in front of the tube.

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We made a prototype Joule-Thomson micro-cooler that was fabricated on Si wafer by photofabrication. The micro-cooler in the present study uses ethylene as a refrigerant. Inlet and outlet gas pressures are set to 2.5MPa and 0.1MPa, respectively. There are slits on counter-flow heat exchanger to prevent heat flow to the cold region along Si wafer. Evaporator temperature reached 270K with pressure of 2.5MPa and mass flow of 9.98mg/s, and we confirmed the operation of micro-cooler.

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Heat exchange performance of two stream parallel-flow type gas-gas micro heat exchangers has been investigated numerically. The flow passages of the micro heat exchangers are parallel-plate channels whose height ranges from 10 to 100μm and the length selected are 12.7 and 25.4mm. The numerical methodology is based on Arbitrary-Lagrangian-Eulerian method. The computations were performed for a wide range of the flow rate ratio to obtain the effect of the flow rate ratio, the channel height and the channel length on the rate of heat transfer. The results are presented as a form of temperature contour and the correlation between the effectiveness and Ntu is discussed.

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Conceptual design, fabrication and testing of a reversible thermal panel (RTP) are described. The RTP, which consists of a baseplate, a reversible fin, and a reversible deployable/stowable actuator, is considered as a candidate methodology for thermal control of Venus mission, PLANET-C in order to save survival heater power. A prototype model of the RTP was developed, and deployment test and thermal vacuum test were conducted. The test results demonstrated that the fin deployment angle and its heat rejective capability could be changed autonomously depending on its own temperature.

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Heat-loss effects on the chaotic behavior of cellular premixed flames generated by intrinsic instability were studied by two-dimensional unsteady calculations of reactive flows based on the compressible Navier-Stokes equation. The disturbance with the linearly most unstable wave number, i.e. the critical wave number, was superimposed on a planar flame. As the superimposed disturbance evolved, the cellular-flame front formed owing to intrinsic instability. The unstable behavior of cellular flames appeared at low Lewis numbers and became stronger as the heat-loss parameter increased. The burning velocity fluctuated with time owing to the unstable behavior of cellular-flame fronts. To study the characteristics of the unstable behavior, the power spectrum density of the fluctuation of the burning velocity was obtained. The power spectrum density had a sharp peak, whose frequency corresponded to the typical oscillation frequency of the unstable behavior, and the l/f spectrum was found in low frequency range. Moreover, we performed the time series analysis on the burning-velocity fluctuation. We obtained the attractor, correlation dimension, Lyapunov exponent to study the characteristics of the chaotic behavior of cellular premixed flames. The characteristics depended strongly on the Lewis number and heat-loss parameter, i.e. on intrinsic instability. The results suggest that the present analysis is applicable to the diagnostics of the flame instability.

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Experiments were performed for turbulent premixed flames of CH_4/air/H_2/ mixtures at high pressure to investigate the effects of hydrogen addition on turbulent combustion characteristics. OH-PLIF measurements were conducted to determine the effective Lewis numbers, turbulent burning velocity, smallest scale of flame wrinkles, and local flame surface density. Results showed that the decrease in the effective Lewis number for hydrogen addition ratio of 0.1 is small and mean volume of the flame region and the smallest scale were not affected by H_2 addition. However, ST/SL slightly increased, corresponding to the increase in the flame surface density possibly due to the increase in the grows rate of the intrinsic flame instability.

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This paper deals with the effect of secondary air injection on oscillatory combustion of a turbulent premixed flame. Characteristics of pressure fluctuation, OH^* fluctuation and NO_x emissions have been also discussed. The result indicates that 45deg. injection is effective to stabilize the oscillatary flame, however NO_x emission is slightly increased. And furthermore, it is found that 90deg. injection shows performance to reduce NO_x emission successfully.

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The physical model investigation on the thermoacoustic oscillation in a lean premixed combustor was conducted to develop a closed-loop feedback control system. With respect to the coupling between pressure fluctuation and heat release fluctuation, phenomenologic analysis was used. As a result, we succeeded in explaining the oscillatory combustion mathematically. On the other hand, mixed H^∞/H^2 control algorithm based on the experimental modal analysis for system identification was applied to the closed-loop feedback control system. Consequently, the developed system performed well with the result of 25.2dB reduction.

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The present study is performed to examine experimentally the burning velocity characteristics of lean hydrogen-premixed micro-scale spherical laminar flames in the range of flame radius γ_f approximately from 1 to 5mm, and also macro-scale laminar flames with γ_f>7mm for comparison. The mixtures have nearly the same laminar burning velocity and different equivalence ratio φ(0.3〜1.2). The radius and the burning velocity of micro-scale flames are obtained by using sequential schlieren images. The results show that the burning velocities of micro-scale flames with φ=0.3, 0.5 and 1.2 have a tendency to decrease with increasing γ_f and approach that of macro-scale flames, but such a trend can not be seen for φ=0.7 and 0.9 micro-scale flames.

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A catalytic combustion has remarkable advantages of the low temperature combustion without NO_x emission and the fuel-lean combustion beyond flammability limit. We had already carried out the numerical study on the catalytic combustion in a channel using detailed chemical kinetics with the smooth catalytic surface as an idealized model. However, an actual catalytic surface has roughness of around 0.1mm. So, we tried to examine the effect of surface roughness on catalytic combustion. This paper describes the results obtained by the numerical simulation for catalytic combustion of hydrogen-air mixtures on platinum catalyst. The details of catalytic combustion in a channel, such as temperature and mole fraction in the gas phase, surface temperature, heat release rate and coverage at the catalyst, were obtained.

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An experimental investigation of the effect of the distance between the fuel and air nozzles on NO_x emission at different temperatures and oxygen concentrations of the oxidizer in high air temperature combustion cylindrical furnace was conducted. Highly preheated oxidizer (air and nitrogen) was injected in the furnace through an oxidizer nozzle positioned at the center of the base of the cylindrical furnace. Propane was injected through three different sets of fuel nozzles, one set working at a time. As a result, the emission of NO_x decreased as the distance between the fuel nozzles and the oxidizer nozzle increased. At lower preheating temperatures and lower O_2 concentrations of the oxidizer, the emission of NO_x tends to become lower.

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An experimental study has been carried out on the synthesis of carbon nanomaterials using Ni catalyst in methane/air laminar, fuel-rich premixed flames under atmospheric pressure. By placing a pair of porous media in the upstream and downstream sides of the combustion space, excess enthalpy burning was applied to the methane/air mixture. We have investigated effects of setting position of Ni catalyst and reaction temperature on nanomaterials growth. As a result, carbon nanomaterials with a diameter of from 20 to 50nm have been synthesized in region near the downstream side of the porous medium.

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In the present study, a sooting flame was formed in a reduced-pressure combustion chamber using with a premixed flame of methane and oxygen for the surrounding flame and premixed flame of toluene and oxygen for the center flame. Collected soot samples were analyzed using the high performance liquid chromatography and a gas chromatography to determine the fullerene content of soot and 22 species of PAHs under various conditions. Effects of chamber pressure, equivalence ratio of toluene and oxygen, flow velocity and chamber length to yield of soot like substances and contents of PAHs and fullerenes were discussed. When the chamber pressure increases, contents of PAH and fullerene decreased with keeping a constant soot yield. There were optimal equivalence ratio and flow rate of the center flame for fullerene formation whereas flow rate of the outer flame and chamber length were not essential for fullerene formation. Such chemical species as Phenanthrene, Fluoranthene and Phyrene accounted for large content in total PAHs.

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The cellulose that was one of the main components of woody biomass was pyrolyzed under four conditions. That is, using (a) non-catalytic porous media, (b) non-catalytic porous media and oxidized iron powder, (c) porous Ni catalyst, (d) porous Ni catalyst and oxidized iron powder. The experiments showed that oxidized iron powder as a catalyst is effective in pyrolysis of the cellulose, especially combined with porous Ni catalyst. The gasification efficiency for C atom was around 80% in total amount of C in the cellulose.

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This study focuses on the fundamental characteristics of DME combustion aiming at the development of low-NO_x combustion technology with flue-gas recirculation (FGR). DME has very high potential of applicability of flue-gas recirculation even at the high mixing ratio because of its high burning velocity and low ignition temperature. Combustion tests were conducted with laboratory-scale 11kW combustor, where O_2 concentration and temperature at the combustor inlet was systematically regulated, so that the flue-gas recirculation at various mixing ratios was simulated. The maximum FGR ratio is 86% at the initial air ratio λ=1.5 with preheated diluted air at 600K. The NO_x emission reduced to 13ppm, which is about 10% of that at FGR=0%. The stable combustion sustains even at low oxygen concentration by preheating diluted-air up to near the auto-ignition temperature of DME.

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Super-rich laminar premixed flat flame of dimethyl ether (DME) have been investigated to elucidate the governing mechanism for the highly floating slow velocity flame. A blue flame is stabilized 60-70mm above the burner nozzle at equivalence ratio of 4.0-5.0. The burning velocity and temperature profiles are reasonably predicted by one-dimensional boundary problem solutions coupled with the detailed chemical kinetics model of DME oxidation. It was confirmed in the sensitivity analysis that the important reactions in the very rich flame are those of low-temperature mechanism so that the burning velocity is very weak function of equivalence ratio.

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Numerical simulation is applied to analyze the counterflow premixed flame with chemical kinetics model. The change in the influence of flame stretch on flame structure by equivalence ratio φ(φ=0.55, 0.75, 0.95, 1.15) is investigated. Methane-air premixed gas with a temperature of 300K and atmosphere pressure is spouted from both planes. The spout velocities are changed from near laminar burning velocity to near extinction limit. As a result, the effect of the flame stretch is superior to Lewis number effect when φ is not very small and flame stretch rate is small. Moreover, it is shown that the tendency to the burning velocity, which is defined by the velocity in minimum point of velocity in direction of nozzle axis, do not have a positive correlation with heat release rate.

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Hydrogen/air laminar flame propagating between two parallel plates was modeled with 3D numerical scheme based on reactive Navier Stokes equations with 9 species 21 reactions kinetics. The intrinsic flame surface instabilities were investigated under the condition with heat and momentum loss from the combustion system, which ensembles the situations inside a small scale combustion chamber. The velocity fixed non-slip wall were used for momentum conditions, while two different types of thermal conditions were applied, i.e., adiabatic and isothermal wall to study the effect of heat loss. Dispersion relations were obtained for both conditions with different channel heights. It was found that the reducing the channel height increases the flame surface instability both with and without the heat loss.

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Laminar flame propagation mechanism and flame stability near the flammable limit have been investigated experimentally for a downward tube propagating one dimensional premixed flame. In order to minimize the buoyancy induced turbulence near the tube, the velocity and the thermal boundary layers are controlled by using the wall suction. The flow structures in the tube have been measured by a PIV. The boundary layers control is useful to minimize the turbulence and to extend the flammability limit for the downward propagating premixed flame.

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Flame structures of Turbulent N_2 diluted CH_4 flames impinging with a lean CH_4 premixed flame near the extinction conditions are studied experimentally. Triple boundaries, lean premixed flame surface, lean diffusion flame surface and impinging surface are visualized simultaneously by a laser tomography technique using different tracer particles. The turbulent N_2 diluted CH_4 gas can be reacts with the high temperature burnt gas from the lean premixed flame. Approaching the extinction conditions, the local quenching occurs. The local quenching becomes main trigger to develop the global extinction. However, more than half of local quenching can be recovered by themselves.

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An analysis of flame area was performed for DNS database of turbulent premixed flames. A local flame front at a prescribed progress variable was identified as a local three-dimensional polygon. The polygon was divided into some triangles and local flame area was evaluated. The turbulent burning velocity was evaluated using the ratio of the total turbulent flame area to the planar flame area and compared with that obtained by the reaction rate.

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Direct numerical simulations of ignition and propagating of hydrogen-air premixed flame in two-dimensional homogeneous isotropic turbulence are conducted to investigate the effects of turbulence and equivalent ratio on ignition and propagation process. In the ignition process, eddies stretch the high temperature region and disturb its evolution. The influence of equivalent ratio is weak for the production of intermediates which are needed for ignition. In the propagation process, strong eddies prevent propagating of the flame, and the flame propagates along the edge of eddies. For stoicheiometric condition, the strong eddies near the flame kernel transport the flame into the burned gas and the transported flame shows high heat release rate. However, for lean conditions, the beat release rate is independent of the flame geometry and shows relatively high value.

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Progress in the method of liquid temperature measurement is also helpful in the study on reactive fluid system. Two fluorescent dyes are dissolved in water and excited by one excitation laser sheet in the present study. The one of fluorescent dye has high temperature dependence and another has low temperature dependence. By this way, the ratio of two laser induced fluorescence gives two-dimensional temperature profile without influence of laser intensity fluctuation. Temperature profile when heated air heat up water through aluminum tube and temperature profile when heated air is injected into water as bubble are measured using the laser induced fluorescence ratio of Rhodamine 110 and Rhodamine B. The heating characteristics by two type of heat transfer are compared. The results show that more uniform temperature increase is able to be attained by heated bubble injection into water.

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It is known that the spike is formed in the miscible displacement in capillary tubes under a certain condition. In the present study, miscible displacement with chemical reaction in vertical capillary tubes is investigated experimentally in the condition where the spike is formed. The effect of reactant concentration on the reaction characteristics is focused on. We have found that the initial reactant concentration ratio included in the more-and less-viscous liquids normalized by the stoichiometric ratio of the chemical reaction, ψv, significantly influences the distribution of the products. We propose that the difference in the product distribution is caused by both two factors ; the idiosyncratic shape (spike) of boundary region and the difference between the diffusion coefficient of interdiffusion of miscible two liquids and that of reactants in less viscous liquid.

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When a reactive less viscous liquid is injected into a Hele-Shaw cell filled with a more viscous liquid and displaces the more viscous liquid, viscous fingering involving a chemical reaction forms. Although some experimental studies on this phenomenon have already been reported, a clear understanding of the region where and when the reaction takes place in the fingers has not yet been obtained. Here, by using a novel experimental method which involves switching the less viscous liquid that is injected into the system, we identified the reaction region at a given time under various reactant concentration conditions.

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Effects on flow behavior, viscous fingering in this study, were experimentally investigated of change in rheological property of water soluble polyacrylamide (PAM) solution induced by addition of electrolyte Fe^<3+> Addition of Fe^<3+> scarcely changes rheological property. Injection of Fe^<3+> solution, however, significantly changes viscous fingering pattern in the PAM solution. Measurement of torque required at a constant revolution to agitate PAM solution during addition of Fe^<3+> solution suggests that this significant change in viscous fingering pattern is due to weak chemical bonding produced by chemical reaction between PAM solution and Fe^<3+> solution which can be destroyed by mechanical shearing.

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The flow field of a two-dimensional non-element reactor, which consists of one main flow and multiple branching flows, is numerically investigated. The main flow is flowing steadily with Poiseuille flow pattern, while the branching flow is periodically injected. The flow is stretching and folding by a Poiseuille flow pattern. The periodical injection makes the flow pattern much complicated which enhances the mixing. The magnitude of the stretching, which is defined as an increase in the length of the unit fluid line, increased with increasing the number of the branching flows. In addition, further increase in the magnitude of the stretching is achieved by the phase shift of the injection from multiple branching flow injection

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A technique for measurements of time-space distribution of convective heat transfer has been developed using a test surface fabricated from a thin conductive film heated electrically. The fluctuating temperature on the test surface can be measured using infrared thermograph having high frame-rate. In this work, the upper limit of the fluctuating frequency and the lower limit of the spatial wavelength which are detectable using infrared thermography are evaluated analytically.

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To measure various turbulent temperature fields accurately, a reliable response compensation scheme for the temperature sensors is necessary. In this study, the response compensation schemes we have previously developed are evaluated numerically to investigate the robustness to the instrumentation noises and the validity of the estimation criterions. The present numerical evaluations will help us improve the reliability of fluctuating temperature measurement in turbulent flows.

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In this study, a new sensor is proposed to determine water temperature. This sensor utilizes the difference in measurement length between two laser beams. Both are the test beams, and there is no reference beam. The two beams pass mostly through equal or closely arranged paths ; therefore, the effect of mechanical vibration on the two test beams is expected to be very small. This sensor was installed on a side wall of a vessel. The temperature near the sensor was also measured with a thermocouple as a reference. The response of the thermocouple was enough to follow the change in water temperature because the speed of temperature is very slow. This paper focuses on the confirmation and evaluation of this system of temperature measurement. The temperature measured with this system agreed well with that measured with a thermocouple. It was confirmed that this sensor system is useful for detecting changes in water temperature.

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To investigate fine scale structure of turbulent flows, time-resolved dual-plane stereoscopic particle image velocimetry (TRDPSPIV) system has been developed using high-repetition-rate Nd: YAG lasers for industrial processing and high-speed CMOS cameras. This system provides all three velocity components and nine velocity gradients with high spatial and temporal resolution. The developed system was applied to velocity measurements of a turbulent jet. It is shown that probability density functions of the measured nine velocity gradients agree well with those obtained from direct numerical simulation (DNS). From the results of TRDPSPIV, coherent fine scale eddies of turbulence are identified and those characteristics such as diameter and asymmetry are shown.

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In this paper, a laser-induced flourescence intensity method for the temperature measurement of metallic surfaces was studied. A two-color intensity approach was applied to improve the measurement accuracy. A mixture of two kinds of phosphors Y_2O_2S:Eu and ZnS:Ag, was used to obtain the two color bands and it was excited by the third harmonic of a pulsed Nd:YAG laser(λ=355nm). The ratio between the resulting flourescence emissions was simultaneously measured using two linear image sensors with different optical filters. Using the two-color intensity method, we can dramatically reduce the measurement error due to the lack of uniformity of both the phosphor thickness and the excitation source power.

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We developed the indirect measurement system of temperature field of a heated jet in cross flow by using PIV velocity data and CFD. The buoyancy is caused by the difference of the density with a surrounding fluid in a heated jet. Therefore, the change occurs in the jet form when the crosswind is received. Spread angle, velocity profile, nozzle exit velocity of a heated jet were experimentally measured by PIV, and this parameter is substituted for a numerical calculation as an initial condition. The streamlines obtained from PIV are compared with numerical simulation, and the initial condition is updated until convergence with a certain allowance. After that we can evaluate velocity and temperature fields of the flow.

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TEM photographs of diesel soot particles, i.e., aggregates sampled from two 3 liter diesel engines were analyzed. The photographs show that particles sampled from 1998 model year engine have chain-like shapes, while those from 2004 model year engine have spherical shapes. The mean radius of gyration of soot aggregates, Rg, was measured by a laser-scattering method. The result show that Rg increases with the increase in soot mass concentration, probably due to the increased collision frequency.

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It's clear that the merit of visualized information in combustion chamber results in understanding the many effective physical parameters. But this system needs the modification of an engine and big power laser, very high speed camera. Additionally, it need the much time to transfer the know how for the real engine optimization and simulation models. On-board measurement system has a big merits because it easy to transfer the real engine without modification. Merits are the time and cost of these system. Several systems are commonly installed in a spark plug. This reports deals about the typical kind of method to know the gas temperature under motoring and firing condition using I.R. absorption method.

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One of the methods that has a potential to minimize the formation of harmful ice crystal is a reduction of moisture content of material. An experiment has been done to examine the possibility of preventing quality loss by microwave vacuum drying in preliminary process of food-frozen storage. The experimental results show that decreasing the water content in onion cells is effective to lower the freezing temperature even if the cooling rate is slow. Also, the formation of smaller ice crystal can be achieved by reduction of moisture content in onion cells. Furthermore, reducing the moisture content of oyster before freezing was effective to minimize the drip loss when being thawed.

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Cells and living tissues slightly but always generate metabolic heat as long as they are alive. If the metabolic heat of a small number of cells can be monitored with improving a thermal sensing technology, it plays an important roll in bio-and medical-engineering. In this study, we tried to measure the metabolic heat of Yeast with a MEMS thermopile sensor to study the minimum metabolism detection level. The MEMS sensor showed a power sensitivity of 0.36V/W and a noise equivalent power of 5.6μW in a multi-layer insulation chamber with temperature controllers with a Peltier device and heater. The measured metabolic heat corresponded to 10^5〜10^6 cells, and growth curve of yeast fungus and resultant generation time were similar to general ones.

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Production of artificial organs utilized in vivo and in vitro is the main topic of tissue engineering. However the method of designing their structures and the optimization of their specifications in terms of physiological functions are still not established. Metabolism of living cells that affects physiological functions is the most important data for this purpose. In this study, glucose consumption rate of HepG2 cell line at different temperature and in glucose concentration medium was measured by using the noble system that allows the measurement in steady mass transport condition with small number of cells, c.a. 10^5 cells. The results provided the several parameters of Michaelis-Menten model at different temperature.

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A phenomenon has been observed in which intracellular Ca^<2+> concentration in endothelial cells increases upon application of shear stress (Ca^<2+> response). It is therefore assumed that Ca^<2+> is the second messenger in the transfer of shear stress stimulation into cells. The Ca^<2+> response is also known to spread to surrounding cells (Ca^<2+> wave propagation). The present study investigated the effects on Ca^<2+> spread among cultured bovine aorta endothelial cells (BAECs) upon inhibiting the main intercellular signaling pathways, such as gap junction and paracrine pathways (apyrase, ARL67156, Thapsigargin, GdCl_3), by inducing Ca^<2+> wave propagation due to an intracellular InsP_3 elevation using caged InsP_3

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An inverse method for estimating radiative properties of scattering and absorbing media has been developed. This method allows us to estimate radiative properties of human skin in vivo in wide range of wavelength. In this method, a target planar medium is non-uniformly irradiated by radiation that has passed multi-slits, and the intensity profile of radiation reflected by the medium is measured. The radiative properties, such as extinction coefficient and albedo are estimated by an inverse analysis based on the intensity profile of radiation. We applied the present method for human skin, and estimated the extinction coefficient and albedo of the skin in the visible range of wavelength.

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This study dealt with the measurement of thermal conductivity and thermal diffusivity of biological materials by a noninvasive method with laser heating and infrared thermometry of a target surface. In this paper the error in the measurement of temperature at the heated surface by the infrared thermometer was evaluated theoretically by taking into account of radiation from an absorbing media. The results showed that the temperature measured by an infrared thermometer that uses the wavelength ranged between 3.0 and 5.4μm was about 0.5K lower than the real surface temperature, which resulted in 2% higher and 14% lower values in the estimated thermal conductivity and thermal diffusivity, respectively. The error could be reduced significantly by utilizing longer wavelength, 7.5-13μm, for the infrared thermometry.

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Designing an efficient micro pump is one of the most essential problems in developing micro miniature-sized devices into which multiple functions are integrated, so-called Lab-on-a-Chip or Micro Total Analysis Systems (μ-TAS). A peristaltic pump, in which the channel walls periodically fluctuate in the form of a traveling wave, is believed to be a suitable solution due to its high efficiency, simple structure and low fabrication cost. In this paper, two-dimensional numerical simulation is conducted for a flow in a channel with walls of peristaltic motion and the effect of the amplitude and velocity of the peristaltic wall on the pump performance is studied. Furthermore, the unsteady characteristics of the heat transfer coefficient at the heated wall are also examined.

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This paper deals with both pressure drop and heat transfer characteristics of thixotropic fluid flow through a thin tube experimentally to describe a precise model of blood flow in blood vessels in human body. Bentonite-water suspension was employed as a model of blood which is a thixotropic fluid. Thin PVC tubes whose diameters are from 0.5 to 4mm were utilized as a model of blood vessel. Sample fluid was driven from temperature controlled vessel with rotary pump by which a pulsate flow like blood flow was realized. Pulsation was set from 0.7Hz to 2.7Hz whose range is similar to actual pulsation of human's blood flow. Both the overall heat transfer coefficient and pressure drop through the test tube were investigated under a variety of tube diameter, sample concentration, and flow rates. Uncertainties of thermophysical properties of sample material (bentonite suspension) made the evaluation by non-dimensional numbers difficult. Experimental results showed that the sample concentration had a considerable effect on the pressure drop, while for the heat transfer coefficient, it has small effect within the parameter range of the present study.

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This paper describes evaluation about repeatable motion of an actuator using thin SMA wire applied for assistant artificial heart muscle. Ti-Ni-Cu wire covered by polyimide tube is combined with thin phosphor bronze plate to make actuator, which is small enough to implant in human body. Actuator elastically bends in arch shapes with electrical pulse application. Numerical evaluation using finite element method shows low consumption motion of the actuator with short time pulse application. Motion response of the actuator in water maintained at 38℃ is numerically and experimentally evaluated as 1.4Hz of motion frequency.

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