Measurements of size-velocity correlations and mean diameters have been obtained with a phase-Doppler velocimeter in the space and time domains of an unsteady spray injected by a pintle petrol injector into an inert atmospheric pressure environment of a test chamber. The injector was operated at a constant injection pressure of 3 bar, and with a frequency of 10Hz, while the injection duration was varied from 2.5 to 7ms. The environment was saturated with petrol vapour, so that petrol evaporation was negligible during the experiment. A hollow cone spray with 10°half-angle was observed with the larger droplets outside the centreline and transporting most of the fuel flowrate. Two low velocity transitional periods, corresponding to the opening and the closing of the pintle, were observed with a higher nearly constant velocity period between the two, during which the spray was in a steady state. All droplet sizes moved with similar velocities close to the nozzle, but further downstream in the time and space domains larger droplets moved faster due to their different relaxation times. A change of the injection duration from 7 to 2.5ms reduced the period during which the spray was in a steady state, resulted in lower droplet velocities, but did not affect the atomisation. The advantages and the limitations of the application of the phase-Doppler to spray measurements is discussed.

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Fluctuation of the boundary layer grown on the end plate of a curved duct is studied experimentally for two inlet flow conditions: uniform flow which fluctuates sinusoidally in magnitude and flow which always has a fully developed duct flow profile but which fluctuates in magnitude. For both cases, the cross-sectional mean Velocity, U_m, fluctuates with the Womersley number of 44.3, the ratio of the amplitude of U_m to its time mean value, U^^-_m, is 0.38, and the Dean number based on U^^-_m is 1.28×10⁴. It is found that (1) at the cross section of the duct turning angle of 60°, the fluctuation of the momentum thickness of main flow velocity, U_φ, is very much different with the two inlet conditions, and (2) the distribution of U_φ shows very good agreement with the 1/n power law but flow fluctuation has a great effect on the distribution of the cross-flow velocity component, U_r, very close to the wall.

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The reverse squeezing flow of dilute polymer solutions has been studied by utilizing a flat plate and a spherical surface of a large radius of curvature. In this experiment, the two surfaces are forced to separate by the application of constant forces from a stationary and contacting state. All the liquids used are Newtonian in viscosity. The following points are found by comparing the results of inelastic liquids and viscoelastic liquid. In the case of the viscoelastic liquid, the surfaces separate from each other much more slowly than in the case of the inelastic liquid. This trend is clearly shown when the separation is small. The results predicted by the theory of inelastic fluids with the assumption of the quasi-steady state agree well with the experimental results. The same assumption, however, cannot explain the slow separation effect because of a small contribution of elastic terms.

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This paper proposes a turbulent lubrication theory for finite journal bearings using an algebraic Reynolds stress model. This turbulence model successfully employs the wall damping effect owing to the presence of the mating surfaces of the bearing. The simultaneous solutions of the governing equations are obtained by a finite difference scheme. The present work performs the theoretical analysis with the boundary condition taking into account the occurrence of sub-cavity pressure loop immediately upstream of the cavitation region and investigates the influence of the boundary condition on the bearing performances. The theoretical results are compared with the experimental data and the theoretical solutions obtained by the previous studies. The analytical results give a good agreement with experimental data in the broader range of Reynolds number.

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Oscillation modes of a circular shock wave in a supersonic radial flow were studied both experimentally and theoretically. The pressure fluctuation was measured in concentric positions to investigate the modes of the circular shock wave in the case of mean radii of 70 and 77mm, and the A-D converted signals were statistically correlated. A simple model of an oscillating shock wave was proposed. The frequency of the oscillation increased from low to high values with increasing radius. The oscillation mainly consisted of mode 0 superposed by modes of 1, 2 and 4. The mode 1 is considered to be weak. The experimental frequency of each mode agreed well with the theoretical results.

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In observing axisymmetric shock wave phenomena by optical flow visualization refractive index changes along the light ray path through the phenomena, we have to determine the density distribution of the axisymmetric phenomena by solving the integral equation which relates the change of the refractive index with the fringe distribution. The present paper reports on the result of flow visualization and numerical simulation of spherical shock waves discharged into free space from the open end of a circular cross-sectional shock tube for shock Mach number 1.5 in air. The axisymmetric shock wave flow is visualized by pulsed laser double-exposure holographic interferometry. Its density distribution was quantitatively evaluated from the three-dimensional holographic interferometric fringe distribution. To compare experimental isopycnics with numerical simulation, we used the total variation diminishing (TVD) finite-difference scheme. The computational results agreed very well with the experimental results. The complicated flow field behind an expanding spherical shock wave can be quantitatively observed. A point explosion test was conducted to examine the process of the present data evaluation method to see how much the collimated light deviated across the spherical shock front.

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An experimental investigation of a shock-wave-induced flow past a circular cylinder in a dusty-gas shock tube was made. Joint research was conducted between the Muroran Institute of Technology and the Institute of High Speed Mechanics, Tohoku University. The shock tubes used for the present research had test sections of identical geometry. For a frozen-shock Mach number of 1.3, flow visualization studies were conducted by the schlieren method, using an Imacon high-speed camera in Muroran and a pulsed-laser holographic interferometer in Sendai. The behavior of shock waves past a circular cylinder in a dusty gas, the development of dust-free regions and the formation of vortices behind a circular cylinder were observed in detail.

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A slipstream emanating from a triple point in the Mach reflection of a shock wave, which is assumed to be a discontinuous surface in the three-shock theory, forms a high-speed mixing layer. In the present paper, the slipstream in the Mach reflection has been investigated in detail and visualized by means of the shadowgraph method. Numerical simulation has been performed using the discrete vortex method. Also, the transition from the laminar to turbulent mixing layer and the growth of a fully developed turbulent mixing layer have been studied experimentally and numerically.

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Tube arrays in cross flows sometimes excite the acoustic vibrations of sound fields in ducts. It is very important, for practical applications, to understand the conditions of acoustic resonances in ducts with tube bundles. Exciting forces due to tube arrays of pitch-to-diameter ratio of 1.57 were measured in a water model duct and the characteristics of acoustic resonance in ducts with tube arrays were revealed. The results of the experiments agree with the field test data very well.

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The motion of a small particle in viscous flow through a narrow and sinusoidally wavy channel is studied. Assuming that the ratio of the amplitude to the period, the aspect ratio, is small in the walls of the channel, we find an approximate solution of the equations of motion on the fluid and the particle, maintaining the precision of the third order of the ratio. It is found that there is only one kind of trajectory along which it is possible for a small particle to pass through the channel. The condition under which a particle passes through the channel is found as a relation of the aspect ratio, the Stokes number, the Reynolds number and the amplitude of the channel. This condition is shown concretely in the aspect ratio-amplitude space by choosing the Stokes number and the Reynolds number as the parameters.

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A mathematical method for transforming moire-schlieren data into internal density (and/or temperature) distributions has been presented. The method of transformation, which is applicable to both symmetrical and asymmetrical flow fields, has been deduced by modifying the Maldonado-Olsen's series. The accuracy of the present method was examined with a mathematical model of a density function of the truncated pyramid type. In order to demonstrate its usefulness for asymmetrical flows, temperature distributions in a combustion flame have been measured for a square nozzle. Experimental moire images of the flame were recorded by a video camera, and the integrated light refraction was converted into an internal temperature distribution. The results showed that the temperature profiles in the flame are distinctive owing to the rectangular nozzle, and that the present method is very effective.

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Flow visualizations were carried out in a turbine rotor cascade with and without boundary layer fences, in order to provide an improved understanding of secondary flow and to show the fence effects. The oil flow and tuft screen methods were used. The results were supplemented by vorticity maps from hot-wire anemometry. Only a single separation saddle point was observed upstream of the blade. The distribution of passage vorticities at the exit from the cascade agreed well with the Oseen distribution under an appropriate normalization. The pressure side corner vortex started at the leading edge, while the suction side vortex began where the primary separation line of the horseshoe vortex intersected the blade suction surface. The fences, attached either to the endwalls or to the blade suction surfaces, weakened the secondary flow by trapping the pressure-side legs of the horseshoe vortices. Vortex flow structures with and without fences are illustrated.

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The paper describes a theoretical and experimental investigation concerning the aerodynamic performance of the Wells turbine, in which a stationary blade row is added on each side of the rotor. The entire blade system is symmetrical with respect to a plane perpendicular to the turbine axis. A quasi-three-dimensional flow analysis is developed and used to design and build a turbine model. Experimental as well as theoretically predicted values are presented and indicate that the presence of stationary blades can provide a considerable increase in efficiency.

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Small signal gain coefficients of a supersonic flow CO chemical laser are measured using a shock tunnel facility. A high temperature mixture of CS₂, CS, S₂, S and Ar is produced in a shock tube, where the thermal dissociation of CS₂ diluted in Ar is accomplished by a reflected shock wave. The shock-heated mixture is exhausted through two-dimensional supersonic nozzles mounted at the end of the tube and mixed with the supersonic streams of O₂. Then, vibrationally excited CO molecules are produced in the mixed streams. In the present paper, the dependence of the small signal gain coefficients on the downstream distance from the nozzle, the plenum conditions and the transition branch is studied. The data obtained in the present experiments are available to examine the propriety of the theoretical model which was developed previously.

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In order to investigate the fundamental features of the pool flashing phenomenon of superheated liquids under rapid depressurization, blowdown experiments have been carried out by quickly opening a solenoid valve of an orifice in the top of a pyrex glass vessel. A modified heterogeneous nucleation theory using the pressure relaxation time, in which the initial depressurization process is approximated by an exponential function of time, has been set up for the prediction of the limits of superheat concerning the inception of flashing nucleation. Experimental results indicate that (1) pressure variations within the vessel are characterized by sudden depressurization and subsequent pressure recovery in several patterns of time history depending upon the vaporization process, (2) the limit of superheat for flashing is estimated to be far below the value predicted by the homogeneous nucleation theory, and (3) the violence of the vapor expulsion process with and without test pieces increases inversely with the pressure relaxation time.

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The flow and heat transfer characteristics of regenerator materials were investigated in an oscillating flow not only for a conventional wire net but also for new materials such as sponge metal which can be set up easily in the Stirling engine. The prediction of pressure drop loss was possible by use of the hydraulic diameter as the representative length defined by the friction factor and Reynolds number. The regenerator efficiency and heat transfer coefficient were obtained by measuring the periodic temperature variations at both ends of the regenerators. A new relationship between regenerator reheat loss and regenerator size was also found from the analysis of the experimental data. The effects of the mesh diameter and the length of the regenerator on the indicated thermal efficiency were clarified.

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The normal spectral emissivity, reflectance and transmittance of silicon wafers were measured at a temperature of 950°C and wavelengths of 0.7 to 9μm. The samples were seven silicon wafers with oxide films of 2.2 to 628nm film thickness and nitride films of 48 to 193nm film thickness with small dopant density. It was found that the emissivities of specular surfaces of silicon wafers with very thin oxide films at wavelengths of 0.7 to 8μm were 0.6 to 0.7, the reflectances were 0.1 to 0.3 and the transmittances were 0 to 0.2. The emissivity of silicon wafers with oxide films of more than 75nm film thickness and nitride films of more than 48nm film thickness changed from 0.6 to 1.0 according to film thickness and wavelength. The emissivities and reflectances of silicon wafers were calculated using the free carrier absorption theory considering the interference phenomenon. Calculated results agreed with experimental results.

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In the present study, analytical and experimental investigations were performed so as to clarify the characteristics of freezing heat transfer in porous media saturated with water in a vertical rectangular cavity. In order to establish the momentum equation, the law of conservation of momentum was applied to the fluid in our control volume, and the equation took into account Forchheimer's extension as the resistance to flow in the porous media. Three different sizes of glass, iron and copper beads were used as the porous media in this study. The temperature of the cold wall was kept at -10°C, while that of the hot wall was varied from 2°C to 22°C. Comparisons between the analytical results and the experimental ones show good agreement with the exception of the copper bead results.

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The present study is concerned with the thermal characteristics of free convection in the locally fully developed region within vertical channels. Similar to that in the well-known internal convection channel flow, the flow field may include entrance region and fully developed region simultaneously as channel is long enough. For locally fully developed region, velocity distribution and Nusselt number as well as generalized temperature profiles in terms of bulk mean temperature are carried out analytically by solving the momentum and energy equations. The existence of locally fully developed region is then confirmed numerically with the solutions for developing flow at far downstream. Results for three different combinations of thermal boundary conditions on the respective wall surfaces (i.e. isothermal-isothermal, isoflux-isothermal, and isoflux-isoflux) are provided to extensively illustrate the substantial influences of heating conditions with closed-form expressions.

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This paper is concerned with developing natural convection in an open-ended vertical annulus with two rotating boundaries and a uniformly heated inner wall. The governing equations have been numerically solved; the obtained results show the effect of a rotating outer boundary on the developing tangential, axial and radial velocity profiles and the pressure distribution across the annular gap. Also, results are presented to clarify the effect of the outer cylinder rotation on the temperatures of the two walls and the relationship between the annulus height and the volumetric flow rate. For the special case of a stationary outer cylinder, the development of the tangential boundary layer displacement thickness in an annulus of radius ratio 0.9 is given, so that Astill's stability criterion can be utilized.

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In the present experiments, a transient method was used to study the heat transfer characteristics of mist cooling. The effects of surface wettability on the heat transfer coefficient and the minimum temperature of the high-temperature region, which corresponds to the film boiling region, were investigated. The heat transfer surface was made of aluminum and was 15mm in diameter and 2mm in thickness. The wettability of the heat transfer surface was varied by surface treatment. It was found that with higher surface wettability, the minimum temperature required is also higher. The experimental conditions of mist flow were as follows: the air velocity V_a was 20m/s; the temperature of the water droplet T_l was 21°C; and the volumetric droplet flow rate D was in the range of 0.00057 to 0.00472m³/m²s.

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To pave the way for the development of a high-performance mist-cooled heat exchanger, heat-transfer tubes with a variety of surface configurations such as grooved, wire-wound, and screen mesh wound tubes, have been developed on the basis of the results of a smooth tube. The effect of surface configuration on heat-transfer enhancement is clarified experimentally and theoretically in connection with the fluidity and extension of liquid film.

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Unsteady heat conduction and transient boiling heat transfer problems during quenching are studied experimentally and numerically. The relation between the hardness of S 45 C steel and the temperature of cooling water is also examined experimentally. The cooling curves of a gold cylinder under various subcooled conditions of water are measured and the transient boiling heat transfer is calculated using those results. The experimental cooling curves for different diameters of steel were measured using the CA sheathed thermocouple. The cooling curves during quenching were calculated using an implicit finite difference method. The characteristics of transient boiling heat transfer of a gold specimen to liquid subcooling from 0 to 80 K became clear. A model including the effect of curvature on the measured boiling curve was constructed. The calculated cooling curves using the boiling curve model as the boundary condition agreed well with the experimental results of steel. High cross-sectional and surface hardness are obtained below 40°C.

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A method of observing the distributed reaction zone in turbulent premixed flames was proposed. A mixing layer between a combustible mixture and a hot burned gas, which existed in a uniform shear layer, was studied to observe the interaction between the turbulence and reaction. A typical wrinkled laminar flame appeared when the equivalence ratio of the mixture was 0.65, and for an equivalence ratio far below the flammability limit, a structure which looked like a distributed reaction zone was observed. In the latter, an intemediate reactedness and the broadening of reacting zones were predicted by the detection of fluctuating temperature, ion current and chemiluminescent emission in the zone.

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An experimental study was conducted on the structure of the wake flame formed behind a porous sphere from which methane was discharged into a uniform stream of dust-free dry air. Laser Raman scattering was applied to measure the temperature and the number densities of gaseous molecules in the flame. Flame thermometry was based on the measured results of the Stokes-Raman spectrum of the nitrogen molecule which was subjected to the monochromatic irradiation of the argon laser (488nm). The chemiluminescence emission spectra of the flame were also measured. The results showed that the maximum temperature was observed near the periphery of the visible flame. The ratio of the number densities of oxygen to nitrogen molecules in the central portion of the flame was much lower than the value in room air. Strong OH emission was observed near the maximum-temperature region.

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The structure of propagating turbulent flames in premixed propane/air (artificial) mixtures in a constant-volume bomb has been observed with schlieren photography, where the characteristics of the mixtures, including the laminar flame thickness, laminar burning velocity and oxygen concentration, as well as the turbulence intensity of the flow field, have been varied independently. The obtained schlieren images show that the complicated schlieren fringes increased rapidly as the turbulence intensified; this is attributed to the superimposition of the increased individual schlieren images of small flamelets existing within the flame zone thickness. The schlieren images were then analyzed using a model for the fine structure of propagating turbulent flames. In the model, a turbulent flame is considered as a mingling of a wrinkled laminar flame and a distributed-islands flame ; the characteristic reaction rate of the turbulent flame is determined by the Damkohler's number and the characteristic reaction time of each flame.

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Experiments were performed to reveal the effects of the equivalence ratio and the turbulence characteristics on the combustion of a propane-air homogeneous mixture. A turbulent flame propagating nearly axisymmetrically in the swirling flow was produced in a disc-type combustion chamber. The burning velocity S_T, the burning zone thickness δ_T of turbulent flames and the laminar burning velocity S_L were measured under various conditions. The main results obtained are as follows: (1) both S_T and S_L depend on the equivalence ratio and achieve maximum values under the condition of slightly rich mixture (2) the value of δ_T increases with the increase of S_T/S_L and there is a correlation between δ_T and S_T/S_L; (3) the ratio of the main stage of burn duration to the total burn duration decreases and the ratio of the early stage increases with the increase of turbulence intensity, and these are almost independent of the equivalence ratio.

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The influences of oxygen, water vapor, ammonia and hydrogen concentration on the DeNOx process by ammonia were investigated by varying their initial concentration levels and the reaction temperature over wide ranges. The experiments were carried out with the use of a flow reactor system and by measuring nitric oxide and ammonia concentration. The experimental results were compared to the computer simulations based on the reaction scheme proposed by Lyon et al. While the Lyon reaction scheme qualitatively predicts the influence of the initial concentrations on the reaction process, large differences are found between them in the lower temperature region, particularly in the case of oxygen and water vapor effect. The prediction of the influence of hydrogen and ammonia is improved by the modification of certain reaction rate constants; however, this barely improved the prediction of the oxygen and water vapor effect.

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The control of SO₂ emissions from a coal-burning Rijke-type pulsating combustor has been studied by adding limestone or dolomite in the combustion zone. The limestone or dolomite particles employed in the study are divided into three classes, i.e., 0.5mm, 1.5mm and 2.75mm mean size, while the mean size of the coal particles is 12.7mm. Results from the experimental tests show that the optimal sulfur removal temperature is about 880°C which is consistent with those from conventional combustor tests. The percent of sulfur retention achieved can be as high as 98% by using dolomite particles of 0.5mm in size and Ca/S=3.6. The results show that as far as the sulfur retention is concerned, the Rijke-type pulsating combustor performs better than another conventional combustors.

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A new optical measurement technique of tip penetration of a diesel fuel spray was developed. In this technique, arrival time of the spray tip at various locations distant from a nozzle was measured by detecting the interception of light sheets by a spray (the light sheet interception method). Then, the relation between the spray tip penetration and the time from the start of injection was obtained. The measurement accuracy was verified by photographing the spray intercepting the light sheet. The photograph shows that this new measurement technique is capable of measuring the spray tip penetration much more easily than the conventional photographic technique, and has sufficient accuracy. The effects of the operating conditions on spray tip penetration were also investigated by this technique. The measurement results of spray tip penetration varied with each continuous injection cycle, and the scattering increased with increasing distance from the nozzle or increasing ambient pressure.

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The paper presents a theory on combustion similarity in diesel engines and contributes to the realization of scale-model experiments. The theory is based on the correspondence of fundamental equations of change and the correspondence of both initial and boundary conditions for different-sized engines. The equations of change consist of continuity, motion, and energy equations, which apply for phenomena with combustion-induced flow and density change. As a result of the investigation, it was found that there exists a possibility of combustion similarity for different diesel engine sizes. The similarity conditions identified involve engine configuration, injection system, fuel properties, swirl ratio, engine peed, droplet size of the fuel spray, temperature of the cylinder wall, and ignition lag.

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