The present study concerns an experimental investigation of the instability of a Taylor vortex flow with two immiscible fluids. The fluids are used containing aqueous solution of glycerol and silicone oil. The experiments are made in a symmetric system and at a range of the aspect ratio approximately from 4 to 6. As results, a cell configuration is clarified by flow visualization, and through a surprising phenomenon where there are opposite directions of flow on a boundary surface between the fluids. The heights of cells are measured to clarify the instability of the vortices. The critical Reynolds number at which the primary mode is mutually bifurcated to the secondary mode and another critical Reynolds number at which the secondary mode changes to the wavy Taylor vortex flow are investigated. These results are compared with the features of the Taylor vortex flow with one fluid and are similar to those in an asymmetric system. But the phenomenon that there are two flow directions on the boundary surface has never been reported.

抄録全体を表示

A steady flow in an non-deformable porous layer subjected to a fluid stream is studied analytically and numerically. One side of the layer of sponge is bounded by a solid wall and the other by a layer of fluid. The fluid is injected uniformly from a plane, through which the fluid can pass, set up parallel to the sponge layer. The flow in the sponge layer is assumed to be governed by Darcy's law. The problem considered is solved in terms of a similarity solution. The equations governing the fluid flows in both the porous layer and the fluid layer and the fluid layer are reduced to a system of the ordinary differential equations. These equations are solved analytically for three cases ideal fluid flow, low Reynolds number flow and high Reynolds number flow. On the other hand, these equations are solved numerically for the general case by using the finite difference method. The distributions of the velocity and the pressure in both layers are found for various parameters. In particular, the speed which the fluid intruds into the sponge layer due to the injection of the stream from the plane is found to be a function of dimensionless parameters. To find this speed is essential to the understanding of porous material.

抄録全体を表示

A turbulent interaction model between gas and coarse particles to calculate the gas particle flow in pipes using the κ-ε model is proposed. A two-way coupling calculation is carried out, based on the Lagrangian approach for the particles and the Eulerian approach for the gas. Governing equations are solved numerically to give particle velocity, concentration, pressure loss, gas velocity and turbulent intensity, which are compared with the results of LDV measurements as well as published data.

抄録全体を表示

Investigations into the flow pattern and heat transfer in pulsating pipe flows have been reported by a number of authors. However, there are few studies of the case in which free convection is produced by buoyancy forces. It was shown in a previous paper (1995) that free convection in pulsating laminar flow occurs when the temperature differences between air in a room and water in an unheated pipe are large. Under such experimental conditions, cross-sectional distributions of axial velocities were obtained for water by means of a hot-wire anemometer. There have been very few investigations into theoretical analysis of pulsating laminar flows with free convection in horizontal tubes. In this case, the theoretical method reported by Mochizuki and Hatta (1973) is applicable only to relatively low values of the parameter ReRa (Re : Reynolds number, Ra : Rayleigh number). Therefore, this numerical analysis which is applicable to a high ReRa regime is presented. The influences of frequency on velocity and temperature distributions are examined, and the calculated results are qualitatively compared with the experimental data reported by authors previously.

抄録全体を表示

The main purpose of this work is to calculate the developing turbulent structure for flow over large-amplitude wavy surfaces. In the calculation, and algebraic Reynolds stress model and a boundary-fitted coordinate system are applied to a turbulent flow in a channel containing wavy wall, in order to precisely solve the anisotropic turbulence. This turbulent flow is complicated, involving accelerated, separated and recirculating flows. The calculated results are compared with the experimental mean and the fluctuating velocities for the flow over a solid sinusoidal wave surface having a wavelength of 50.8mm and a wave amplitude of 5.08mm. For this flow, the experimental results show a large separated region. The present method predicts the locations of separation and reattachment without much discrepancy. The present model has been found to simulate characteristic features of the flow, but it has a tendency to show the different profiles near the wavy surface and to overestimate the value of the mean velocity. For the streamwise velocity fluctuation, the calculated results show similar profiles except at near-wall region. Moreover, a cross-sectional view shows that with this method, we can see how the secondary flow and the separated region develop. The calculated results show that a large variation of the secondary flow is generated close to the corner region of the wavy surface as a result of the pressure gradient.

抄録全体を表示

This paper presents the results of a two-dimensional stability analysis on supersonic flow relative to a cascade, using actuator disk methods. The results show the possibility of existence of two types of destabilizing mode in the supersonic cascade flow. One mode corresponds to conventional rotating stall in subsonic cascade flows. This mode can be unstable both in subsonic and supersonic regions, and its propagation velocity ratio is smaller than unity. The other mode is a newly found mode unique to supersonic cascade flows. This mode can become unstable only in the supersonic region, and its propagation velocity ratio is in most cases larger than unity. Both modes become unstable due to the positive slope of the characteristic curves produced by flow compressibility as in the case of, for example, a shock wave.

抄録全体を表示

When introducing the TVD method to the system equation, it is important to treat discontinuity near the shock waves. Flux splitting method handles this discontinuity by separating flux at the cell interface. The flux splitting method is divided into two categories : FDS (Flux Difference Splitting) and FVS (Flux Vector Splitting). However, they have some defects. For example, in the case of FDS, it becomes diffcult to maintain stability because of strong expansion wave. Also, excessive numerical diffusivity makes the results far from the reality in the case of FVS. Recently AUSM (Advection Upstream Splitting Method) has been proposed. In the present paper, a blunt body with a compressive corner are investigated using three flux splitting methods. We demonstrate the efficiency of AUSM, compared to the other flux splitting methods.

抄録全体を表示

Since it is of great importance to have efficient numerical methods for large-density-gradient flow fields having little compressible wave effects, the authors have developed a Navier-Stokes simulation scheme by both reconstructing the entropy equation and filtering out compressible wave effects from the compressible Navier-Stokes equations. Simulated flow fields, including the Benard problem and the Rayleigh-Tayler instability problem, show excellent agreement with theories and experiments ; thus, not only the efficiency of the scheme, but also its accuracy are confirmed to be valid.

抄録全体を表示

A two-dimensional numerical simulation of feedback control of a thick flat-plate wake in a high Reynolds-number region was performed using the discrete vortex method. The transverse velocity component on the wake centerline was used as a feedback signal, and the feedback input was given to two separating shear layers at the trailing edge of the plate. A fair amount of reduction in periodic velocity fluctuations typically occurred when the feedback sensor was located downstream at a distance 2.7 times the plate thickness, while the total turbulence energy in the wake was not greatly affected by the feedback. The dominant frequency in the wake changed rapidly or almost discontinuously as the sensor location passed through the critical location.

抄録全体を表示

The detonation wave caused by the combustion of a liquid fuel film coated on an inner tube wall has recently attracted considerable attention because of its possible role in explosion hazards in compressed oxygen pipelines. This type of detonation is known as "film detonation" and is classified as a heterogeneous detonation. The structure of a heterogeneous detonation wave is very complex because physical processes such as momentum, heat and mass exchanges between liquid film and the gas phase are coupled with a chemical reaction. Experiments are conducted to investigate the initiation process of film detonation using high-speed schlieren photography and direct photography. It is clearly observed that a secondary shock wave caused by the combustion of liquid fuel film plays a significant role in the transition of film detonation wave.

抄録全体を表示

We present a correlative mapping method for measuring individual phase flow rates of an airwater two-phase flow. First, we extract stochastic features of a fluctuating pressure difference in a Venturi tube placed just downstream of an eccentric elbow, and second, we evaluate its individual phase flow rates based on pattern recognition for a data base, which is constructed beforehand, Experiments in an air-water loop showed that individual phase flow rates can be measured within an accuracy of 4.7% for the air phase and 4.0% for the water phase, and that method is applicable to the measuring management for production rate at well heads in offshore oil fields.

抄録全体を表示

In an experiment on two-phase flow, it is often necessary to measure the void fraction distribution. The contact probe method is used because of its simple structure and low cost. This method is effective for determining local void properties, but ineffective for measuring void fraction distribution because the threshold of the probe signal voltage varies with the flow patterns. To overcome the difficulty in void distribution measurement, we applied the fuzzy set rule taking into consideration the properties of the probe. We propose a new probe measurement method of the void fraction using membership functions, and show that the method enables us to eliminate the dependence on flow patterns.

抄録全体を表示

Acoustic resonant vibration occurs in a cavity with tube bundle when gas flow reaches a certain velocity. However, it does not always occur even though the condition that vortex shedding frequency coincides with acoustic natural frequency is satisfied. Fluid forces supply energy to acoustic resonant vibration and acoustic vibration consumes this energy to maintain vibration. Acoustic vibration does not occur if energy consumption is greater than energy supply and vice versa. The mechanism of the vibration was discussed in the previous paper [1] and energy consumption was also presented in the paper [2]. In this paper, judgment of vibration is made in terms of energy supply and consumption. Unsteady fluid dynamic force exerted on vibrating cylinders is measured instead of that produced in the flow with acoustic vibration. Energy supplies due to the fluid dynamic force are calculated and compared to the damping force. It was clarified that energy supply and consumption markedly depending upon the shape of cavity and portion of tube bundle.

抄録全体を表示

We have investigated the stability and vibrational response of magnetic liquid columns held by Helmholtz coils. Theoretical resonance frequencies were derived from the linear potential theory prior to the experiment. During the experiment, a small quantity of a kerosene-based magnetic liquid was injected onto a lower pole plate. When the magnetic field was increased. a cylindrical column (height=9.78mm) was vertically formed between the two pole faces of the iron core Helmholtz coils. When the magnetic field was decreased, the column diameter exhibited hysteresis such that the column broke at a smaller diameter than that at formation. The coils holding the liquid column were then excited horizontally and the lowest mode (m=1, n=1) derived theoretically appeared in the measurements. The surface frequency response was measured optically using a CCD camera, a strobovision analyzer and a stroboscope for various magnetic field intensities and aspect ratios (mean diameter/height). We found that the resonance frequency of the mode (m=1, n=1) decreased with increse of the aspect ratio. The experimental resonance frequencies were in qualitative agreement with the theoretical predictions.

抄録全体を表示

An upward plane jet, impinging on the free surface of a shallow rectangular tank, oscillated in the absence of external periodical force. The frequency and the oscillation conditions were clarified. The position of the surface swelling created by the jet impingement, the pressure difference between the two sides of the jet and the flow velocity on the bottom near the jet inlet were measured, and their phase relation was examined. The fluttering jet was visualized using ink and the displacement was measured using an image-processing technique. The jet behavior was simulated well by a simplified model in which the distributed jet velocity was represented by the mean axial and transverse velocities.

抄録全体を表示

Jet-flutter is a transverse oscillation of a submerged upward plane water jet impinging directly on a free surface. The movement of the impingement point results in additional fluid mass being left on the surface, which does not balance with the momentum supplied by the jet. The imbalance results in generation of progressing waves and of a surface level gap at the impingement point. The level gap is restored not by the waves progressing laterally but by the vertical motion of the water column. The above model explains well the following two major characteristics of jet-flutter : the frequency corresponds to that of water column oscillation in a partitioned tank with the same water depth, and the oscillation region has a wide range above a certain velocity limit determined by the water depth.

抄録全体を表示

As a part of the investigation of a device which removes dust particles from the panel of a solar heat collector or solar cell, a sprinkler which applies a flow oscillating mechanism has been designed and improved. In this study, the effects of the geometrical condition on the spread angle and the distribution of the sprinkled water are investigated. From the results, it is found that the spread angle of the sprinkled water widens as the exit width of the sprinkler and diameter of the pressure recovery hole become larger. However, at a certain exit width or diameter, the spread angle obtains a maximum value, then decreases gradually. The distribution of sprinkled water changes also with the exit width and the diameter. Moreover, the output power of the solar cell has been measured in order to prove the effects of this sprinkler.

抄録全体を表示

By use of a highly water-repellent coating wall, a new type of drag reduction for a rotating disk in a Newtonian fluid has been found experimentally. Measurements were carried out to investigate the torque of rotating disks with a highly water-repellent wall and with a smooth aluminum wall. The clearance between the disk and the wall was varied, at 5, 10, and 20mm. The tested fluids were tap water and aqueous solutions of glycerin at concentrations of 30 and 40wt%. The experimental data of the frictional moment of the rotating disk obtained using the highly water-repellent wall were smaller than those of the smooth aluminum rotating disk. It was shown that the maximum drag reduction ratio was about 45% in a 40wt% glycerin solution at about Re=10⁵. and the viscosity of the fluid has a slight effect on the drag reduction.

抄録全体を表示

Experiments have been conducted to investigate thermal-hydraulic instabilities at system pressure ranging from 1 to 7.2 MPa in a boiling natural circulation loop with a chimney. Stability maps in reference to the system pressure, the channel inlet subcooling, and heat flux are presented. Two different types of instabilities were observed in the facility at relatively low and high system pressures. Both of the instability mechanisms were clarified by investigation of the transient flow pattern and the response of the driving force of the circulation to momentum energy.

抄録全体を表示

For clarification of the mechanism of heat and mass transfer in the early stages of superheated steam drying which accompanies condensation and evaporation, an experiment in which a water surface was used as a dried material was conducted under atmospheric pressure. Temperature profiles for in both the gas phase and the liquid phase near the water surface and the liquid level were measured precisely. From the results, heat transfer rates at the water surface and the amount of steam condensed into water were determined ; in addition, the relationship between these two was investigated both experimentally and theoretically. Furthermore, a characteristic curve of drying accompanying condensation and evaporation in the early stages of superheated steam drying was derived semi-empirically. In this drying characteristic curve, there is a point at which neither condensation nor evaporation occurs. This is defined as the "reverse point". Introduction of this reverse point. and the time ratio for condensation and evaporation during the early stages of superheated steam drying are clarified.

抄録全体を表示

The effects of the convection term and the inertia term on the Nusselt number in laminar-free convection condensation of pure saturated vapors are separately discussed. Based on the results, the following equation is proposed : [numerical formula] where Nuo denotes Nusselt's equation. The above equation contains a few errors due to the ρμ ratio. When we use integrally averaged values over the wall temperature, vapor temperature for C^^-_pl. and values at the film temperature for all other physical properties in the above equation, it correlates well the previous numerical results on the Nusselt number for water and carbon dioxide near the critical regions.

抄録全体を表示

Molecular dynamics simulations have been conducted for a monatomic-molecule system in order to understand the effects of translational motion on condensation and evaporation. The condensation probability of an argon molecule was examined by injecting a test molecule into the liquid system with a different translational energy. For evaporated and reflected molecules, velocity distributions in the vicinity of the liquid surface were measured and compared with the Maxwellian distribution. The results show that both condensation and evaporation coefficients depend on the normal component of translational energy. The condensation coefficient increases with an increase in incident energy because it can penetrate the liquid surface. Likewise, the evaporation coefficient increases with translational energy because of its increasing ability to escape from the liquid surface. It was also found that the velocity distributions of evaporated and reflected molecules should be expressed using the condensation/evaporation coefficient.

抄録全体を表示

This paper is concerned with the melting of a vertical ice plate under the condition of an initially no temperature difference between the ice and a calcium chloride aqueous solution, in which the melting rate can not be analyzed using the classical Stefan problem where in the temperature gradient at the melting front is controlled. The numerical results with the concept of a diffusion controlled melting revealed a stable concentration stratification above a layer strongly convecting, uncontaminated liquid clearly observed in flow visualization, and also successfully predicted the melting rate quantitatively having not yet considered previously.

抄録全体を表示

The diffusion coefficient of a cryoprotectant mixture in biological tissues consisting of multiple cells is measured. Obtaining reliable information on physico-chemical properties is essentilal to clearify the process of cryopreservation of biological tissues, because absorption of the cryoprotectant into the cells prior to programmed freezing is necessary to avoid overgrowth of the ice nuclei formed in the intracellular solution. For the measurement, porcine arteries are used as the test specimens, assuming a steady distribution of the concentration of the cryoprotectant mixture inside the tissue ruled by Fick's law. The diffusion coefficient of the cryoprotectant mixture in biological tissues is determined by comparing the experimental time-sequential data of the concentration of the cryoprotectant mixture, whic the analytical solution of the concentration of the cryoprotectant mixture, which can be described by an exponential curve. Values are obtained as a function of temperature. With this diffusion coefficient and membrane permeabilities, an optimum pre freezing process might be designed.

抄録全体を表示

Void fractions of liquid fluidized beds were measured using water as the fluidizing liquid. Particles of glass, ceramics and chromium were tested, and their diameter range was from 1.87mm to 8.34mm. Fluidization columns having a diameter of 51, 34, 21 and 8mm were used. A void fraction measurement was performed for each particle column combination. Based on the experimental data, a new correlation was derived which enabled over 95% of the data to be predicted within ±7%. Existing correlations were also reviewed and compared with the results.

抄録全体を表示

Natural convection heat transfer in a circular enclosure, one half of which was heated and the other half of which was cooled, was investigated experimentally, focusing on the effect of the inclination angle. The experiments were carried out with water. Flow and temperature fields were visualized by using the aluminum and liquid-crystal suspension method. The results show that with downward heating the heat transfer coefficient increased as the inclination angle of the boundary between the heating wall and the cooling wall approached vertical. But with upward heating, the heat transfer coefficient showed minimal change, exhibiting a small peak value when the inclination angle was γ≒-45°. The heat transfer coefficient of a flat circular enclosure was estimated from the circular enclosure's heat transfer coefficient. These results can be explained by the obtained flow and temperature fields.

抄録全体を表示

An experimental study has been conducted to determine the heat transfer characteristics around a circular cylinder attached to the separated flow of air shed from a fence. The fence was located vertically to the flow with a height of H=40mm. d/H was constant at 0.638, where d is the cylinder diameter of 25.5mm. X/H were 0.50, 0.775, and Y/H ranged from 0.525 to 1.50, where X and Y are, respectively, the distances between the axis of the cylinder and the front face of the fence, and the bottom wall of the test section. The Reynolds number Re based on the cylinder diameter and the velocity of the undisturbed flow ranged from 1.9×10⁴ to 6.0×10⁴. It was found that the maximum local Nusselt number changes drastically in the vicinity of Y/H=1.0∼1.11, and that the maximum mean Nusselt number occurs in the neighborhood of Y/H=1.24∼1.43 for X/H=0.50, and 1.3∼1.4 for X/H=0.775.

抄録全体を表示

Two-and three-dimensional numerical simulations have been performed for mixed convective upward flows over a backward-facing step in a duct. The Reynolds number, expansion ratio and aspect ratio (in 3D sim.) were kept constant at Re=125, ER=2 and AR=16, respectively. The heat flux at the wall downstream of the step was uniform, while the straight wall, the step and the side walls (in 3D sim.) were assumed to be adiabatic. The effect of the buoyancy level, Ri^*, was the major interest in this study. It was found that the reattachment point and the peak Nusselt number point moved upstream as Ri^* was increased, while the secondary recirculation region, which developed at the corner of the step, became larger. It was also found that there existed a secondary flow in a cross section immediately downstream of the step. Flow directed toward the center of the duct becomes more intensive as Ri^* increases, which possibly results in an increase in the level of three-dimensionality of the flow and thermal fields.

抄録全体を表示

In order to pursue the effects of surface position, size and structure on the enhancement and control of mist cooling heat transfer, detailed experiments have been conducted regarding the boiling and evaporation of liquid film formed on circular superheated surfaces with smooth, concentric grooves and radial grooves. These results indicate that a vertical surface is more efficienct in the enhancement of heat transfer than a horizontal one, a smaller surface produces higher heat flux, and the grooved surface is more effective in the enhancement and stability of heat transfer. It is also clarified that the optimum size and structure are determined from the sprayed mass flow rate and degree of superheating.

抄録全体を表示

To understand the fundamental mechanism of how light absorption is converted into the thermal energy. the atomic motion of matters are studied using the quantum molecular dynamics method. As the fundamental atomic system, several metallic atoms are considered to be irradiated with light by changing the frequency and intensity. Under infrared light irradiation, the increase in the kinetic energy and atomic dissociation are attributed mainly to the dipole moment fluctuations of ions. Under the irradiaiton of light at electron energy levels, the change in the kinetic energy and dissociation are resulted from the change in the potential energy between particles due to electron excitation. This mechanism causes the characteristic difference in the kind of fragments and atomic motion under various light irradiation.

抄録全体を表示

Turbulent scalar transport phenomena at high Prandtl numbers of up to Pr=100 were examined through direct numerical simulations of forced isotropic turbulence with a constant mean temperature gradient. The main storage capacity required for computation was significantly reduced by employing a different number of mumerical grids for each of the velocity and temperature fields, which contained markedly different microscales. At high Prandtl numbers, the pressure temperature-gradient correlation is found to be dominant, instead of the molecular dissipation, as the sink term in the turbulent heat flux budget. It was also found that low wave number components of the velocity fluctuation are solely responsible for the cascade of the temperature fluctuation irrespective of the Prandtl number.

抄録全体を表示

A graded structure with multiple functions is required to construct a radioisotope (RI) heat source for a new energy generating thermoelectric conversion system. The first function is to obtain as high a surface temperature of the heat source structures as possible, and another function is a radiation shielding function. This structure is a cylinder, composed of RI-SrTiO₃ as a heat source and BN as a radiation-shielding material. The composite RI cylinder must be designed to maximize the surface temperature and to minimize the radiation intensity on the cylindrical surface. It is proposed that an optimum graded distribution of RI-SrTiO₃ exists which satisfies the two distinct requirements.

抄録全体を表示

A super refuse power plant is a new type of refuse power plant which has a gas turbine as a component for superheating refuse steam and improving plant thermal efficiency. The purpose of this study is to clarify the effectiveness of this method and to find the optimum capacity of the gas turbine for a given conventional refuse power plant.

抄録全体を表示

Recently, gas turbines have been used as key components of a variety of combined cycle power plants including integrated coal gasification combined cycle and humid air turbine etc., and their characteristics strongly influence the total performance of these power plants. The purpose of this article is to demonstrate the usefulness of a relatively simple model of gas turbine performance, which is commonly applicable to modern air-cooled high temperature gas turbines. Gas turbine performance in such combined cycles can be estimated with the model calibrated by the simple cycle data of the turbine.

抄録全体を表示

The effects of unstable thermal stratification and mean shear on chemical reaction and turbulent mixing were experimentally investigated in a liquid mixing-layer downstream of turbulence generating grids with and without a rapid chemical reaction. Experiments were carried out in both an unsheared unstably-stratified flow and a sheared unstratified flow. Instantaneous velocity and concentration were simultaneously measured using a two-component laser Doppler velocimeter (LDV) and a laser-induced fluorescence (LIF) technique. From these turbulence signals, turbulence quantities such as intensities and power spectra of velocity fluctuations, turbulent mass fluxes and the Reynolds stress were estimated. Furthermore, the total amount of reaction product was estimated from the transverse concentration profiles of chemical product. The results show that the turbulent mixing is enhanced at both large-and small-scales by buoyancy under unstably-stratified conditions and that the chemical reaction is also promoted. The mean shear acts to enhance the turbulent mixing mainly at large scales but the chemical reaction rate is not so large compared to the unstably stratified case. The unstable stratification is a good tool to attain the unsheared mixing since the shearing stress acting on the fluid is much weaker in an unstably-stratified flow than in a sheared unstratified flow.

抄録全体を表示

A numerical simulation of a premixed flame stabilized by a bluff body was performed using LES turbulent model and a new turbulent combustion model. In the previous work, the authors evaluated a local quenching effect due to a flame stretch and proposed a new combustion model including turbulent effects. The model also includes temperature effect of unburned gas and the pressure effect in a combustor. Due to the strong organized motion created by the bluff body, we could see fluctuations of the premixed flame. Further more, the distributions of the time-averaged velocity, temperature and intensity of the velocity fluctuation were compared with experimental data. The calculated results were in good agreement with the experimental ones.

抄録全体を表示

In order to clarify the relationship between fuel spray characteristics and combustion characteristics, combustion tests of the premix and prevaporization combustor were carried out. The lower flammability limit becomes leaner for a longer vaporization pipe and combustion air with a higher temperature and larger velocity. On decreasing the total equivalence ratio, the carbon monoxide concentration first decreases and then increases beyond the equivalence ratio of 0.6. The nitrogen oxide concentration increases exponentially with increasing total equivalence ratio. At temperatures higher than 1779K, the majority of the nitrogen oxide emission is generated by Zeldovich's mechanism. At temperatures lower than 1779K, the influence of the flame temperature on the nitrogen oxide emission is smaller than that at higher temperatures.

抄録全体を表示

An experimental study was carried out in a constant volume combustion chamber for clarification of the effects of non-homogeneous concentration distributions of the fuel-air mixture on the flame propagation. The mixture of propane-air was prepared by the reciprocating movements of a pair of perforated plates. The laser sheet Rayleigh scattering method was applied for a quantitative visualization of the mixture concentration fields, and the degree of inhomogeneity of the mixture distribution over the measurement plane was determined. The flow in the chamber and its turbulence characteristics were measured by the Laser Doppler Velocimeter technique. The degree of inhomogeneity of the mixture distribution decreases with increase of the number of the reciprocating motion of the perforated plates. The turbulence intensity decays rapidly after mixing. By changing of the mixing numbers and the delay time after mixing, the distribution of the mixture and the turbulence intensity can be changed independently, which makes it possible to investigate the effects due purely to the mixture heterogeneity on the flame behavior.

抄録全体を表示

These have been much interest in the use of vegetable oils as diesel fuel since they are domestically produced and are a renewable energy source. The present work describes the results of experiments using stable water-emulsified rapeseed oils and gas oil in a swirl-chamber diesel engine. Furthermore, NO_x, HC, CO, and smoke emissions and energy consumption are compared with experimental values from a direct-injection diesel engine with no changes in engine equipment. The results show that a swirl-chamber diesel engine is more appropriate for use with water-emulsified rapeseed oils with regard to NO_x, HC, CO, and smoke emissions and BTE. In addition, NO_x and smoke emissions of emulsified rapeseed oil are lower than those of gas oil in a swirl-chamber diesel engine.

抄録全体を表示