Boundary layer velocity characteristics for different curvatures are compared experimentally, and the parameters which include the effects of convex curvatures are analyzed. The shape-factor of velocity defect profile G is determined to be a significant parameter which control the convex turbulent boundary layer velocity characteristics. And the skin friction formula by Ludwieg-Tillmann is satisfied for any size of convex curvature adopted in this report. The problem of the turbulent characteristics, it is cleared that a parameter, μ²_pw/(R·g) is important to detemine the effects of convex curvatures.

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The entrance flow patterns for Newtonian fluid and polymer solution are simulated by using the complex potential. The results of the simulation show the same entrance flow patterns as those obtained by the vizualization. The ratios of vortex and suction intensity are shown as a function of the Weissenberg number (N_we.) at low Reynolds numbers (N_Re.) and of N_Re and N_we. at high Reynolds numbers.

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A rapid expansion of moist air or steam in a supersonic nozzle gives rise to condensation and the total pressure of the flow is reduced by this nonequilibrium phenomenon. In the present paper, a method is presented for calculating a loss in total pressure due to condensation generated by a rapid expansion of moist air in a supersonic circular nozzle. The loss in total pressure has been determined from the amount of increment in the entropy produced as the result of the irreversibility in the nonequilibrium condensation process. The calculated results of the loss in total pressure are a little smaller than those of the experimental results, and the values are about 2 to 5 percent in the present calculation. Based on the calculated results, the effects of the degree of supersaturation of moist air and the shape of nozzle on the total pressure loss have been made clearly in quantity.

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The purpose of this paper is to elucidate the fundamental features of the vorticity induced by the flow withdrawn through a hole at the center of the bottom of a vessel. The problem to be solved is based on the unsteady axsymmetrical flow composed of a solid rotation which is generated by a tangential injection of feeding water at infiinity. The numerical solutions are computed using the initial value of the well-known Bodewadt's solution in the case without a sink. It is shown that there exists a dividing streamline of the sink flow along the bottom surface of the vessel from the main flow beyond its streamline. The nature of the axial circulation in the container is characterized by the combination of Lewellen or Burger's vortex flow based on stagnation-point flow within the region about a vorticity core with Bodewadt's solution for the case of no sink.

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It is important to know the deviation from the two dimensional flowfield in an axial-flow fan. In general, the centrifugal force and pressure gradient in radial direction in the flowfield around a blade row designed as a free vortex design do not balance except in the far field. Imbalance between the two forces was calculated based upon a two-dimensional potential-fiow theory. The calculations of the flow inside and outside a blade passage were carried out by the method of conformal mapping. Imbalance of a large scale over one blade pitch was found to dominate over the other ones of small scales and this was also found to be large in magnitude especially near the leading edge of the blade. It is highly probable that the effect has a nonnegligible influence on turbomachine characteristics.

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It is important in the flow around cascades, helicopter rotors, and flaps, to study the nonlinear interaction of forces on each foil and the wake patterns. In this paper, we construct a numerical method for the unteady imcompressible flow around two·dimensional oscillating multi-aerofoils by using both the discrete vortex approximation and the surface-singularity method. In this method, a simple Kutta condition is proposed and the flow around the airfoils is simulated by distributing vorticities linearly on the surface of the airfoils and point vortices in the wake. In this paper, the numerical calculation is done for a single foil. The numerical analysis has been developed for the wake configuration, forces and moments on airfoils.

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This paper is mainly concerned with the dynamic structure of a high speed water jet, the damage process of metallic materials and a microscopic comparison of cavitation damage. The experimental conditions were an injection pressure of 30 to 90 MPa and a nozzle inner diameter of about I nun. Materials tested included aluminum, mild steel and stainless steel. The instantaneous behavior of impact pressure was measured using a pressure transducer. Comparisons among stroboscopic observations for the structure of a water jet, axial variation of the impact pressure and mass loss of the material caused by the jet impact showed that the axial location where the water jet begins to break up coincides with the one indicating the maximum fluctuation of the impact pressure and it is close to the location of the maximum mass loss of the material. We have made a detailed comparative observation of the damage processes for a water jet and for cavitation (magnetostrctive vibratory method) using a scanning electron microscope and found some distinct differences in the damage process.

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Momentum theory of diffuser augmented wind turbine (DAWT) or all-directional wind acceleration tower (ADWAT) was treated, basically with Bernoulli's equation, the actuator disk theory and the equation of continuity. Then, output coefficients of the turbine were deduced as functions of load factor of the turbine, area ratio and efficiency of the diffuser. Through the numerical computation and the investigation of the resulting equations, the following has been ascertained. If there is no momentum loss in the diffuser flow, the maximum output coefficient of the turbine, based on the diffuser exit area, is found to be 0.385 with suitable combinations of the load factor and the area ratio. The effect of the diffuser efficiency becomes severer in the case of a larger area ratio of the diffuser and a lighter load factor of the turbine. Hence, it has been suggested that the reasonable area ratio of the diffuser and the load factor of the turbine are around 1:3 and 0.5, respectively. The output coefficient of the turbine based on the turbine area may be expected to be about 0.7.

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Instantaneous flowmeters are indispensable to analyze dynamic behavior of pipelines and hydraulic systems. Therefore, it is very important theme to establish the method to measure accurately and easily unsteady flowrate of liquid through pipelines and hydraulic systems in real time. Recently we developed a simple instantaneous flowrate sensor making use of cylindrical chokes. In this system, the dynamic relationship between the pressure drop across the choke and the flowrate through the choke is utilized and calculated by a micro computer system. The numerical operation in real time is performed by newly devised exclusive hardware circuits, in which sampling period is set at 78μs. In this report, we proposed a new improved method to provide some advantages on the numerical operation for the instantaneous flowrate measuring system. Introducing tables on memories (RAM) which are set in advance and applying Runge Kutta method give following advantages: unnecessity of another expensive hardware circuits, improvements of accuracy in high frequency region and capability of correspondence to system parameter changes.

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A method of measuring three dimensional velocity components using a single slanted hot wire probe is presented. The method is applicable to a periodically fluctuating flow and of course to a steady flow. In this method, the hot wire output is measured at three yaw angles of the probe and the nonlinear simultaneous equations which give the velocity components are solved by an iteration method. A smoothing technique is used on the velocity components to suppress the scatter of the components and also to avoid a large error in the measurement. A measurement is carried out in the scroll of a centrifugal fan under the condition that a rotating stall of the vaneless diffuser occurs. The applicability of this method is proved from the experiment.

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A practical technique comprising two V-shaped hot-wires in an X array is proposed for the simultaneous measurement of the instantaneous streamwise and lateral velocity components in low velocity turbulence. The accuracy of the technique is investigated by an error analysis in simulated Gaussian velocity fields generated by means of a digital computer. The result shows that turbulence quantities obtained by the proposed technique are reliable and significantly more accurate than those by a conventional X-wire even in high-intensity turbulence. Furthermore the measurement of a natural-convection boundary layer along a flat plate has proved that the V·shaped hot-wires are highly effective for the measurement of near-wall turbulence at low velocities.

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The upper cooling surface temperature of the layer is fixed at the freezing point of 0°C and the lower heating surface temperature is fixed at a prescribed temperature such as 7, 10, 15, 20, 25 and 30°C in this experiment. The bead diameter employed in the porous layer is 5, 11 and 15 mm for glass beads, and 11 mm for steel beads. The layer depth is fixed at 25, 50, 75, 100 and 125 mm. It is found in this investigation that the Nusselt number decreases with decreasing surface temperature heating at the prescribed Rayleigh number due to the maximum density of water, and the effect of the maximum density on natural convection becomes small when the lower heating surface temperature is larger than about 25°C.

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An experimental study using a hot-wire anemometer was conducted to investigate fully-developed turbulent flows within ducts of a cross-chaped cross-section. Extensive measurements of mean velocity and Reynolds stress fields were made at 972 measuring points distributed over an entire cross-section. Examination of the experimental data including the secondary flow velocities and separation of normal stresses, confirmed that the flow field acquired a high degree of symmetry in all planes of symmetry. The resulting contour maps of various quantities were compared against the numerical calculation results based on Launder and Ying's algebraic stress model. The overall performance of the algebraic stress model was found to be satisfactory. The model, however, tends to underestimate the size of secondary vortices generated near the convex corner. Moreover, discussions were made on the secondary flow vorticity production in connection with isovels. The present study may give certain information which may be useaul for a further improvement of the stress model.

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A mechanism to accelerate hot water in a pipe by boiling of liquid freon injected in the hot water was developed with the final object being to drive a Pelton wheel. Characteristics of the acceleration were measured by using a convergent nozzle, a convergent-parallel nozzle and two convergent-divergent nozzles with different divergent angles, and the relation between the reaction force of the jet and the flow rate of the liquid freon was obtained. When using the convergent nozzle, the experimental values were lower than the theoretical ones. In the case of other nozzles, the experimental values were higher than the theoretical ones under certain conditions such as high temperature and liquid freon injection of small amounts- It is considered that this phenomenon comes from the addition of acceleration of water vapor which is generated at the nozzle throat because water is agitated strongly by the freon gas. The convergent-divergent nozzle with a small divergent angle shows excellent characteristics.

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The laser Rayleigh scattering technique has been applied for the time and space resolved measurements of vapor concentration in the boundary layer formed around a droplet evaporating in a uniform field of air stream. The droplet evaporation is simulated by a porous sphere method to remedy the inaccuracy arising from the distortion and the fluctuation of droplets in a conventional suspended droplet method. The results show that the optical system provided in the present study is successful in identifying the Rayleigh scattering light unaffected by the background noise due to the reflection of the incident laser beam. The time averaged concentration is observed to be fairly uniform, except in the vicinity of the surface. A low concentration region exists in the central portion of the wake. It is also indicated that an increase in Reynolds number causes a decrease in the boundary layer thickness, while the concentration profile remains similar.

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A new apparatus to measure the thermal diffusivity of liquids based on the forced Rayleigh scattering method was developed. Verification of the theory and examination of error factors have been carried out through measurement of the thermal diffusivity of toluene and water. The error factors examined in the present study were; sample layer thickness, concentration of dye and heating pulse duration time. Through these considerations, appropriate experimental conditions for the measurement were determined. To demonstrate the applicability of this method, the thermal diffusivities of toluene, n-hexane and methanol have been measured at room temperature. The accuracy of the present measurement was estimated to be±3 %. The present study may lead to the conclusion that the forced Rayleigh scattering method has considerable potential of being applied to measurements for electrically conducting liquids at high temperature.

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The operation of a solar total energy experimental facility, which generates heat energy and electric power by solar energy, had been initiated in September 1982. This facility is operated by selecting one of three operating modes according to the conditions of insolation and storage temperature of a heat storage unit. Furthermore a load control mode is provided with the aim of supplying either more electric power or heat energy. In a previous report, the outline of the facility and experimental results of operation by an electric load control mode were reported. Based on these results, a part of the heat collection loop and low temperature heat recovery loop was remodeled to increase the system efficiency. In this remodeled facility, experiments on the heat load control mode were carried out and a summary of all the experimental results is described in this paper.

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In this paper, the annual performances of solar heating and cooling systems for different values of system parameters are predicted by computer simulation. The prediction is based on the characteristics of solar collectors, absorption chillers, and so on that are reported in my previous papers. The system parameters varied in the simulation are the storage capacity, the collector area, the collector flow rate, the flow rate of hot water in the heating system, the flow rate of chilled water in the cooling system, and the slope angle and azimuth of the solar collectors. As a result of evaluating the values of the system coefficient of performance based on fossil energy, ε_S, under the various system parameters, it was found that a few parameters have the optimum value where the ε_S has a maximum.

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Acoustic transmission measurement techniques for large boiler furnaces were studied and developed. It was found in fundamental acoustic transmission tests that l0-12 kHZ acoustic waves were suitable for measuring combustion gas distribution in boiler furnaces. A few kinds of computer programs for CT (Computed Tomography) were written and discussed. The program based on the method of least squares was most convenient in cases where few data were available. Then, we performed the measurement of combustion gas temperature distributions in a test furnace. The data were reduced using the above CT program. The temperature distribution calculated by the CT program is very similar to and favorably agrees with the results measured by a suction pyrometer. The maximum temperature difference between the two methods is 5 percent in the 700∼1000 °C temperature range.

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Air, fuel gas and fuel-air mixture injection into a recirculation zone formed behind a thick burner rim were examined. Flame stability limits, residence times in the recirculation zone and inflow ratios of injected gas were measured. Flame stability limits were widened by fuel or mixture injection. Mixture injection was most effective. The length of the recirculation zone and residence time in the recirculation zone with injection coincided with these without injection. Inflow ratios of the injection gas in the recirculation zone were about 80% irrespective of the injection rate or mixture strength of the injected gas.

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The flame length of swirling diffusion flames of gaseous fuel was measured by means of photography for several swirl intensities of the gas flow at the burner exit. Hydrogen, mixture of hydrogen and propane and acetylene were employed as fuels in the experiment and were issued vertically from a cylindrical swirl burner in free air. The flame length increased gradually with increasing gas exit velocity and then became a constant independent of the exit velocity in fully developed turbulent region. The intensity of the swirl was observed to have a strong effect on the flame length. The constant turbulent flame length was obtained as a function of the stoichiometric concentration of the gaseous fuel and the swirl intensity at the burner exit by modifying the swirl intensity to the empirical equation of a nonswirling turbulent diffusion flame.

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In order to reveal the effect of turbulence on the combustion process of a propane-air mixture, a turbulent flame propagating nearly axisymmetrically was produced in a disc type combustion chamber. The velocity and turbulence of the gas flow in the combustion chamber were measured with a two-dimensional LDA system. The configuration and propagation speed of the flame were measured with high-speed laser schlieren photography and an ion-probe. From these measurement results, the burning velocity ST and the burning zone thickness δ_T of turbulent flames were determined success-fully under various conditions of turbulence intensity. As a result, it was recognized that the value of ST increased with increasing turbulence intensity and δ_T increased with S_T.

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A new method is proposed to accomplish a wide range and low noise level pulse combustion in the case of natural ventilation. It is found that a supply of a rich mixture, instead of pure fuel, which is outside the rich inflammability limit and has an equivalence ratio of 3.0 in the present experiment, can realize a higher combustion intensity of 53.4 MW/m³ and a larger turn down ratio of 4.5 than those of the usual pulse combustor. A rather silent pulse combustion, whose noise level is 55-70 dB(A) without any silencer. is possible by operating the present combustor at a 15-35 partial load. The volumetric efficiency of a pulse combustor, defined by the ratio of the total volume of fresh mixture and air supplied per cycle at NTP to the volume of the combustor, is found to vary within the range of 4-12 %. corresponding to the minimum and maximum combustion load, respectively. As a result, the volumetric efficiency may be expected to be an important design parameter of the pulse combustor.

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A constant-volume combustion system has been developed to reproduce direct-injection stratified-charge combustion, which is regarded as a promising concept for lean combustion. A fully premixed mixture consisting of N₂, O₂ and H₂ was ignited to obtain a high pressure and temperature occurring at the top dead center in a real engine. The H₂ in the mixture is oxidized by a part of the O₂; thus, a N₂-H₂O-O₂ mixture can be prepared before the injection of iso-octane fuel. Velocities of the swirling air in the vessel were measured by hot-wire anemometry and combustion was analyzed from schlieren photographs and combustion pressures. The results show that a compromise should be achieved between burning velocity and NOx and HC emissions by adjusting the swirl level.

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It is necessary to estimate the turbulent burning velocity in the cylinder of a spark-ignition engine, in order to refine the entrainment model which is often used for modeling engine combustion. Nevertheless, the effect of turbulence characteristics on the burning velocity has scarcely been studied in a spark-ignition engine. We have investigated those in constant volume vessels of disc and cubic types. In this study, the turbulent burning velocity, S_T, and the thickness of the burning zone, δ_T, were determined in a spark-ignition engine cylinder. As a result, it was made clear that S_T and δ_T increased with increasing turbulence intensity, and that δ_T Was correlated linearly with S_T except under the condition of weak turbulence.

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