The results of experiments on the thermal effect for tubes of different tapers are presented, and the effects of the tapering of the tube on the internal flow are shown. The results are summarized as follows: (1) With a tapered tube a higher temperature is obtained with smaller intervals of nozzle-tube spacings compared with the cylindrical tube. (2) With a tapered tube a higher frequency of flow oscillations and a shorter penetration length of contact surfaces which are considered to cause a higher temperature in the tube, together with stronger shock, are obtained (3) The velocity history at the open end is different for tubes with different tapers. When the taper is small, the amplitude of the velocity change becomes very small. (4) The pressure amplitude at the closed end becomes large for tubes with large tapers.

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The characteristics of the aerodynamic damping of a row of casacded blades in transonic flow are examined by the "one blade oscillation method" we developed formerly. Concerning the aerodynamic interaction between neighbouring blades, we uncovered some hidden aspects in the overall results obtained by the "all blades oscillation method" and it is made clear that there exist obvious differences between the aerodynamic interactions in transonic compressible flow and incompressible flow. In the present report, we treated a case of turbine cascade with a high stagger angle but a low turning angle. In the next report, we will treat the case of a transonic turbine cascade of high turning angle with practical blades.

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Unsteady responses of two dimensional aerofoil cascade to three dimensional sinusoidal gust are examined by linearized frameworks of analysis in which the steady velocity is assumed to be of a finite order but the unsteady one of an infinitesmal order of magnitude. The main results are summarized as follows: (i) The rotational part of unsteady velocity is obtained by integrating a certain relation derived from Euler's equation of motion on the orthogonal curvilinear coordinate system without treating directly the vorticity. (ii) The unsteady volocity potential of the Poisson equation is obtained numerically by applying the boundary element method to the integral equation of Fredholms type of the second kind derived from Green's theorem, and then the unsteady pressure distribution over the aerofoil and the unsteady forces are determined. (iii) some notable interactions between the steady load of cascade aerofoil and the vorticity of a sinusoidal gust and three dimensional unsteady effects on pressure distribution and fluid forces are clarified for the compressor and turbine cascades in the sinusoidal gust of in-phase and out-phase inflows.

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A rough estimate of flow physical properties in a chemical vapour deposition system has shown that Reynolds numbers in the circular tube reactor of the system are changed from the order of 10^-1 up to 10², and Knudsen numbers from the order of 10^-2 down to 0.0. Finite-difference solutions with viscous and slip flow boundary conditions of the equations of motion for an incompressible flow over a disk in the tube have been obtained for a range of Reynolds numbers from R_e=5 to R_e=10². The vortex lengths behind the disk are found to increase with the Reynolds numbers and the radius ratios of the disk and the tube. By rarefied gas effects, the vortex in a slip flow regime is smaller than that in a viscous flow. The results of liquid flow visualization using an aluminium dust method are in accord with the finite-difference solutions with a non-slip boundary condition.

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This study is intended to clarify the flow pattern in the flow developing region of an axisymmetric laminar water jet issuing into the surrounding calm water. The jet, having initially a potential core region to some extent at the nozzle exit, was studied. The velocity profile in the developing region near the nozzle was measured by using a miniature hot film probe of a cone type. Flow visualization by the hydrogen bubble method was also performed. Experiments were carried out for the jet Reynolds number from 100 to 600. The flow pattern in the developing region was made clear, and the extent of the developing region also discussed. The experimental results were compared with the existing numerical solution.

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Fully developed plane Couette flow at the transitional Reynolds number is simulated numerically without any model representing the effect of turbulence smaller than the size of computational grids. Upwind scheme proposed by Kawamura and Kuwahara is applied to the direct integration of the three-dimensional, time-dependent Navier-Stokes equation of motion. In this study the procedure necessary to examine the equivalence of the numerical result to the real flow is considered, and the effect of numerical diffusivity of the upwind differencing is evaluated. From the numerical results, the outstanding features of the low Reynolds number wall turbulence are discussed. Furthermore, the model of small scale turbulence in Large-eddy simulation is also tested using the results of direct numerical simulation. It is infered that the Smagorinsky model can not be applied to the highly anisotropic turbulent shear flow of a low Reynolds number without any modification.

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In the present paper the mass transfer of a substance such as oxygen in a pulsating flow through a two dimensional stenosed channel has been studied. In the experiment both local and mean mass transfer at the wall behind the stenosis are measured by an electrochemical method. Measurements are conduced in a Reynolds number 150. Schmidt numbers 1100 and 1600 and a non-dimensional pulsating frequency range 1.0-7.0. The mass transfer is numerically estimated by the continuity equation, the vorticity transferred equation and the diffusion equation. The local mass transfer at the region just behind the stenosis is lower than that away from the stenosis, and its pulsating amplitude at the former region is smaller than that at the latter region. From the frequency characteristics of the relative mass transfer, the time when the mass transfer at the region just behind the stenosis decreases is remarkably affected by the pulsating frequency.

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In order to demonstrate the applicability of an inverse cascade design method for blade design for an axial turbomachine, rotor and stator blades of a single stage axial fan are designed and tested. This design concept, proposed in the previous reports, is based on an inverse boundary layer method and an inverse cascade method. Overall performance and the rotor exit flow field are measured and are compared with a conventional fan designed using NACA 65 series cascade. The inversely designed fan obtains higher efficiency and a wider operating range compared with the conventional one. The midspan wake of the rotor blade in the trailing edge region reveals an extremely low velocity defect, a low wake shape factor, and low momentum thickness. boundary layer separation on the rotor blade suction surface seems to be avoided and the losses are low. The experimental results show the validity of the practical aplication of the inverse design concept, especially for rotating blades.

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This paper presents a new real time measuring method of unsteady flow rate employing a centerline velocity in a circular tube. Transfer functions which relate variables in axially symmetrical laminar flow can be obtained by mathematical analysis. We applied an approximate function of transfer function between the centerline velocity and the mean flow velocity to the measurement of unsteady flow rate. An analog electronic circuit whose transfer characteristic is equivalent to the approximate transfer function can be made easily, since it is composed of a proportional element, two first order lag elements and an element based on the second order lag element. The real time measurement of unsteady flow rate can be realized with the analog electronic circuit by inputting a measured signal of the centerline velocity to it. The validity of this method is clarified experimentally by comparing it with another measuring method whose validity has been confirmed.

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A fully developed turbulent flow in a square duct, two opposite walls of which had been roughened by square cross-sectioned ribs, was measured using a hot wire anemometer. This paper presents the resulting velocities and stresses, and compares them with measurements taken in a square duct with four smooth walls. Symmetrical results, relative to the axes of symmetry of the duct cross-section, were obtained in such areas as mean axial velocity, turbulent kinetic energy, and <u₁, u₂>^^-. Asymmetrical results, however, showed up in <u₁, u₂>^^- and in the secondary velocity vector. As is well know, smooth-walled ducts yield two secondary flow cells in any given quadrant of a cross-section. But in ducts whose opposite walls have been roughened, we found a heretofore unobserved phenomenon: only one relatively large cell appeared in each quadrant of duct's cross-section.

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A hot-wire response equation for a system of a constant temperature anemometer was derived in terms of experimentally easy-to-handle angles of rotation. Approximate response equations for two-dimensional laminar flow were also obtained to explicitly express the influence of the error angles of the direction of the hot-wire on the anemometer output. Those equations were confirmed to agree well with experimental data. Based on these approximate equations, the quantitative influence of various directional error-angles on the output was obtained and the relation of the yaw factor to the directional error was examined.

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A statistical pattern recognition method was applied to the analysis of the signals of cross-sectional mean void fraction for discriminating gas-liquid two-phase flow regimes. The anaysis and discrimination were carried out based on six key flow patterns: bubble, cap-bubble, plug, froth (F_I and F_II), and annular flow. For each flow condition 100 void signals with a recording dimension of 1 second were used and transferred to discrete data, the sampling frequency of which was selected at 100 Hz by comparison between correct recognition rates obtained from different frequencies. The magnitude of the time-averaged void fraction was partly employed supplementary to the pattern recognition method. The boundaries between the six flow regimes were determined corresponding to a correct recognition rate of 80% and drawn on a superficial gas-liquid velocities diagram. These flow boundaries were also compared with those available in the literature.

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The effect of a difference in the form of a poppet top on the performance of an oil hydraulic poppet valve is investigated experimentally. The flow characteristics, thrust performance, noise level and cavitation limit are researched on the three different shaped poppet valves: type (A) the conical poppet, type (B) the conical with a flat part on the top, and type (C) the cylindrical form. It is made clear that the flatness on the top of a poppet in type (B) has a great effect on the valve performance in the case of converging flow, and a difference in a seat angle in type (C) makes a great change in cavitation condition, flow characteristics and noise level in the case of diverging flow.

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Spool valves are often used under the condition of cavitation. In this research the effects of cavitation on the flow rate and the axial flow force were investigated experimentally for the square-land type and the taper-land type spools. By making the half cut model of the spool valve, the occurrences of cavitation were observed and the distributions of pressure on the surface of the spool were measured. As a result of this research, the change of the flow rate and the axial flow force by the cavitation and the limit of cavitation occurrence were made clear.

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A simple equation for expressing the blade loading of an impeller and a modified Wiesner's slip formula taking account of this blade loading are presented. The performance of four different types of impeller with the same exit diameter, blade exit width, and number of blades was tested. Further, the slip factor of all impellers were measured by using a three hole pitot probe. The slip of the impeller was affected by the blade loading, especially by the meridional distribution of blade angle. A modified Wiesner's formula showed a better prediction of the slip factor of the impeller.

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Natural convection fields right above a heated horizontal circular cylinder have been examined mainly by a hot-wire anemometer calibrated for the thermal effect in a rather low air flow range, using a two-dimensional (temperature-velocity) spline function. As a result the following facts have been revealed: (1) The interpolation by a two-dimensional spline function is applicable for the calibration of a hot-wire anemometer in a rather low velocity region. (2) There is a somewhat undeveloped convection region in the natural convection field right above a heated horizontal circular cylinder. These facts are ascertained by means of a laser-doppler velocimeter and by a flow visualization method using a smoke-wire. Moreover, they are ascertained by a numerical calculation of the natural convection field, too.

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Visual observations of flow patterns at the condenser and heat transfer measurements were conducted for heat transfer rate ranges of 18-1800W using a vertical annular device with various quantities of R113 as a working fluid. As a result of visual observations, it is shown that ripples (interfacial waves) are generated on the condensate film surface when the condensate film Reynolds number exceeds approximately 20, and the condensation heat transfer is promoted. A simple theoretical analysis was presented in which the effects of interfacial waves and vapor drag were considered. This analysis agreed very well with experimental results when the working fluid quantity was not so large that the two-phase mixture generated by boiling of the working fluid didn't reach the condenser. The effects of interfacial waves and vapor drag on condensation heat transfer were also investigated theoretically.

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In order to pursue a high performance mist cooled heat exchanger, a fundamental study of mist cooling has been performed on a heated circular cylinder in a spray flow. The collision of droplets on a cylinder surface was analyzed, taking account of the dispersion of droplet and its trajectories. Characteristic equations were obtained by comparison with the experiment. The condition of liquid film formation was also obtained, assuming that the liquid droplets were stagnant on the heated surface.

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In order to pursue a high performance mist cooled heat exchanger, the heat transfer mechanism of mist cooling on a heated circular cylinder is discussed experimentally and theoretically. In the experiment, visual and photographic observations are made, in addition to the measurements of the heat transfer rate. Analyses are performed on heat transfer enchancement, taking account of the dynamical behavior of the liquid film. These results are shown to correlate with existing experimental data.

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This paper describes the effects of free stream turbulence on turbulent heat transfer from flat plate without pressure gradient. Measurements of velocity, temperature, and their fluctuations were performed carefully by I-I-V type anemometry. The remarkable increase of turbulent Prandtl number, especially in the buffer layer, was observed with the free stream turbulence. Also, the calculated local Nusselt number, approximated by considering this effect of turbulent Prandtl number, agreed well with the measured values.

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The characteristic quantities of turbulent diffusion flames are simultaneously measured by Rayleigh scattering and the LDV system. The co-axial turbulent diffusion flames formed by the mixed fuel of 62.2% H₂+37.8 % CH₄ and air, in which the Rayleigh scattering cross sectional area changes within 5% by combustion, are ;measured. The temperature and velocity characteristics obtained from one thousand simultaneous data pairs of temperature, and the velocity obtained by permitting a time difference of 102 μs between these two signals because of the masking of the Rayleigh signal by the Mie scattering from thee particles introduced for LDV measurement, almost agree with the values calculated from ten thousand pieces of data obtained from independent measurements. The typical probability density functions of temperature and velocity for the turbulent diffusion flames are obtained. The distribution of <v'T'>^^- could not be predicted by the simple turbulent flame theories.

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The Spontaneous ignition of fuel sprays injected into a steady hot air flow by hole-nozzle with a single hole was studied. In the present study, the effect of the chemical factor on ignition delay was investigated, using fuels mixed with an ignition promoting additive. The results showed that amyle nitrite, an additive to diesel oil, decreases the apparent activation energy for ignition as well as the delay time itself. Then, a simple model was proposed on the spontaneous ignition of sprays, and it was known that the model can explain the various phenomena obtained in this work fairly well. The discussion suggested that the ignition may be attributed to fine droplets smaller than 10μm, existing in the peripheral region of sprays.

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Vibrational Raman spectra of H₂O and CO₂ were theoretically obtained for the experimental use in temperature determination in flames. The variation of half-value width of H₂O spectrum was used to evaluate the temperature; the relative intensity of the (0, 0⁰, 0)&roarr;(1, 0⁰, 0) transition scattering to the (0, 1¹, 0)&roarr;(1, 1¹, 0) was correlated to the temperature of CO₂. These theoretical predictions are compared with the experimental measurements in H₂ diffusion flames. Rotational Raman spectra of N₂ and CO₂ were also studied by the theoretical predictions based on the correlation of half-value width of spectra to gas temperature, and the results are discussed in comparison with the experimental observations.

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A numerical analysis has been performed extensively with respect to a one dimensional model for radiation controlled flame, where a combustible mixture flows through a porous medium in which the combustion reaction takes place. The comprehensive features revealed in this study may be summarized in the following way: (1) It has shown that a radiation controlled flame is stabilized in a porous medium with extremely high porocity when the combustible gas mixture flows in a porous medium and the structures and burning velocity have been revealed. (2) It has shown that the thermal structures in a porous medium depend strongly on the absorption coefficient and total optical thickness of the porous medium, and their effects on the flame structures and burning velocity have been elucidated. (3) The local and total energy balances of the system have been revealed and the importance of radiation heat loss has been demonstrated.

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In order to elucidate the blowoff mechanism of burner flames, mass burning velocities, tangential components of mass velocities to the ignition front and stretching near the flame base were examined. Experimental results show that the mass burning velocity of a stabilizing point in the flame base at the blowoff limit is larger than that at the lean limit of inflammability. Therefore, it is not a valid interpretation that blowoff occurs as the fuel concentration of the stabilizing point approaches that of the lean limit of inflammability, because of dilution with the surrounding air. Since stretching of the flame at the stabilizing point has a tendency to decrease when approaching the blowoff, the flame-stretch concept can not be applied to it. A model for the stabilization mechanism of premixed flames, in which the boundary velocity gradient theory is expressed algebraically, is proposed to explain the blowoff the burner flame, as well as the inverted flame reported previously by the authors.

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For the utilization of alcohol fuels in automotive engines, it is interesting to note the studies of the use of alcohol for conventional gasoline engines without any design changes, and of supplying gasous fuels for insufficient fuel against the intake air quantity. This paper reports a comparison of the engine performances of methanol plus gasous fuels such as propane, for a compression ratio of 12:1, against those of the base gasoline engine, for a compression ratio of 8.5:1. The test results obtained are as follows: The maximum engine output is higher by about 13%: maximum brake thermal efficiency is higher by approximately 21% at wide open throttle; and engine emissions are lower, especially for NO_x and THC, than those of the base gasoline engine.

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Effects of the volume ratio, nozzle diameter, and the surface to volume ratio of the nozzle (S/V-value) on the initial jet velocity and ignition induction period are experimentally investigated in order to obtain a clear picture of the interrelation between the jet region in the main chamber at the very ignition and the combustion pattern. a reduction of the S/V-value under a constant nozzle diameter increases the initial jet velocity, leaving the ignition induction period almost unvaried. The higher the jet velocity and the longer the induction period, the greater the jet region and the lower the mean temperature within the region, resulting in an extremely rapid combustion in the main chamber. The combustion pattern parameter, derived from the dimensional analysis and defined by X=u_jτ_i/d, is found to be a simple measure to classify quantitatively the ignition and combustion processes in the main chamber independently of the volume ratio, nozzle diameter, and the S/V-value.

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This paper deals with the separation of short-circuit gas from exhaust gas in a two-stroke cycle gasoline engine and the measures to effectively utilize the short-circuit gas. For trial manufacture of the engine, the slide shutter is kept on an open port, and is set on the upper plane of the piston. This is done in order to get control of the exhaust port. The piston moves up and down the side of the exhaust port, which is divided into 3 section areas: upper, middle, and lower. This mechanism in the lower level was able to separate the fuel and air concentrations at a high level, from the exhaust gas. We succeeded in achieving a firing-run on a separated and set four-stroke cycle gasoline engine by taking advantage of its gas.

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The direction of fuel injection in a gas turbine combustor has significant effects on the performance, especially on its flame blow-off characteristics. combustion by two kinds of fuel injection nozzles in the same combustion liner was investigated experimentally by measuring the temperature and gas composition. The combustor with one of the fuel nozzles, which injects fuel inward around the center axis, shows good performance for weak mixture conditions, but experienced a sudden blow-off of the flame at high pressure conditions. Present results revealed that it has a poor flame holding structure without recirculation of hot gas at the moderate mixture condition; whereas it has a stable diffusion type flame at the lean mixture condition. The accuracy and the nature of the obtained temperature and the gas concentration data were discussed.

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The effect of oil film on unburned hydrocarbon (HC) emissions from a spark ignition engine was investigated. a lubricant free piston ring and cylinder were employed to study the interaction between the fuel and cylinder lubricating oil film. Absorption and desorption of fuel vapor into and from the cylinder lubricating oil film was found to account for about 2530 percent of the total unburned HC emissions. The time-resolved lapse of the various species of combustion gas and unburned HC in the combustion chamber and exhaust port were also studied during the combustion, expansion and exhaust processes by means of high speed gas sampling valves. An increase in the amount of unburned HC in the combustion chamber was detected in the expansion and exhaust processes.

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A laser homodyne principle was applied to the measurement of turbulence within an engine cylinder. This method features direct detection of relative fluid motion in a turbulent flow without relying upon time-sequential data. Because of this advantage, cyclic variation biases that may be encountered in ordinary methods are eliminated. The intensity fluctuation of laser light scattered from tracer particles was measured by a high-speed digital correlator using a photoelectron correlation technique. Tests were conducted on a motored engine at several engine speeds and swirl ratios. The results support the feasibility of the proposed method in measuring turbulence intensity and length scale. It has been shown that swirl increases not only the turbulence intensity but also the length scale at the compression end. finally, a discussion is given of the in-cylinder measurement of the swirl velocity by the present laser homodyne method.

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