The conditional equation of balance of a flexible rotor and the possibility of a new balancing procedure by aid of a mode separation network have previously been proposed by one of the authors. This paper deals with some experiments to verify the theory, where a variety of unbalance distributions is artificially given to a seven-disked flexible rotor which is supported by two flexible bearings and is balanced based on our theory. The bearing vibration together with dynamic shaft deflection after balancing is minimized over a wide range of rotational speeds as high as its third critical speed. Thus the theory is experimentally proved to be valid for balancing a flexible rotor.

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In this paper, the vibration and the critical speed of a rotating shaft having two rotors are treated theoretically considering the gyroscopic effect of the rotors and the distributed mass of the shaft. A symmetrical shaft system in which both rotors are symmetrical and an asymmetrical one in which rotors and the bending rigidity of the shaft are asymmetrical are treated using different coordinate systems respectively, and the eigen-frequencies at any shaft speed and the critical speeds are calculated exactly. An approximate formula for the lowest critical speed of a symmetrical rotating shaft system having n rotors by Rayleigh's method and one for critical speeds of higher order by Ritz's method are obtained considering the gyroscopic effect of the rotors, and numerical examples are shown.

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The vibro-indentation with a spherical indenter on low and medium carbon steels was performed in ultrasonic (20 kHz) and in low frequency (50 Hz) ranges in order to establish the foundation for the vibro-Brinell hardness testing that was suggested in our first report. Experimental results show that Meyer's law is still valid in case of the vibro-indentation, provided that Meyer coefficient and index are taken to be the functions of the load amplituae and frequency. It is also shown that the vibro-indentation law and the vibro-Brinell hardness can be reduced to Meyer's law and Brinell hardness respectively, under the "load superposition hypothesis".

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The resonance tube is a cylindrical cavity, closed at the downstream end, which is excited to oscillation by a coaxial air-jet. This paper presents a numerical solution of unsteady, one-dimensional, non-isentropic flow in the resonance tubes by the characteristics method, when the wall friction, the heat transfer and the contact surface are taken into account. The calculations on the flow in tubes are performed numerically under improved boundary condition by the normal mesh method with a digital computer. The calculated results are compared with the experimental ones, and they indicate that the role played by wall friction in the thermal effect of resonance tube should not be neglected in comparison with the shock wave propagating in the tube.

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We previously reported the pressure drop measurements of the flow through the annulus formed by two eccentric cylinders, with the inner cylinder rotating and the outer one stationary. This paper studies the pressure distribution around an inner cylinder and the pressure drop in the annular gap between eccentric cylinders, of which the outer one rotates and the inner one is stationary, under fully developed conditions. The relations between friction factor λ and a few parameters such as axial-flow Reynolds number R_e, rotating Reynolds number R_w, clearance ratio β and eccentricity ratio m, are investigated and compared with the previous results obtained for a rotating inner cylinder. And the effect of axial-flow Reynolds number R_e on the pressure distribution is investigated at some rotating Reynolds numbers R_w, where the rotational flow without the axial one belongs to a laminar-flow region, either of transitional or turbulent type.

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It is well recognized that turbulent pulsations in an electrically conducting fluid are suppressed and a velocity profile is made uniform due to the action of a transverse magnetic field. Murgatroyd measured the pressure gradient during the flow of mercury in a rectangular channl of 15 : 1 aspect ratio in the presence of a transverse magnetic field and suggested that the critical condition for the transition from turbulent to laminar flow was R_e/M=900. However, MHD devices such as conduction electromagnetic pumps used in metallurgical and chemical industries are placed in a relatively short magnetic field and therefore Murgatroyd's criterion for the transition of flows seems not to be applicable due to the end effect. This paper is an experimental study on the influence of an electric and a magnetic field on the transition of flows in a kind of conduction electromagnetic pump. The experiment suggests that in this device, the critical Reynolds number is lower than that based on Murgatroyd's criterion owing to the end effect.

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In order to collect the preliminary design data for the electromagnetic pump, flow-meter and so forth, the investigation of the electrically conducting fluid flowing in channels under an applied magnetic field is so important that many investigations have been conducted. However, most of the investigitions are of laminar flow and those of turbulent flow are rare. The present report is an analytical investigation in which the Prandtl mixing length theory is applied to turbulent magnetohydrodynamic flows in rectangular channels with a large aspect ratio under a transversely applied magnetic field. The results for the resistance coefficient agree well with the experimental ones in the region of small Hartmann numbers and over a wide range of Reynolds numbers. Judging from the present condition of the turbulent magnetohydrodynamic theory, the present analysis is considered to be significant enough for engineering.

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In order to obtain the preliminary data necessary for the design and development of MHD power generators, MHD flow-meters, MHD pumps and so forth, the investigation of the influence of a magnetic field on liquid metals flowing in pipes is very important. The present paper is a report on an analytical investigation for the turbulent magnetohydrodynamic flow of liquid metals flowing in an insulated circular pipe under a transversely applied magnetic field. The values of the mean skin friction coefficient agree well with the experimental ones in the region of small Hartmann numbers. Although the present analytical method is scarcely useful for the elucidation of the flow mechanism, it is considered significant enough for engineering in that the present method can provide the practically important skin friction coefficient.

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Flow visualization, measurements of velocity fields etc. are utilized to determine flow behaviours of dilute polymer solutions. However except in the case such as using a doppler anemometer, it is expected that the influence of insertion of probes such as a pitot tube on the measurement is comparatively large. In this report, a problem of determination of a flow velocity by a pitot tube method is discussed analytically and experimentally. Velocity measurements in a turbulent pipe flow of dilute polymer solutions show that the flow rate determined from apparent velocities, which are obtained with a customary method assuming fully developed stresses, is less than the true value ( 〓of the order of 10%), but the resultant velocity profile corrected by the analysis of the flow field around a pitot tube is in fairly good agreement with that by other methods and the disagreement of the flow rate is improved. These results show the necessity of the pitot tube coefficient caused from viscoelastic behaviour of dilute polymer solutions.

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The first part of this paper, the frequency response of a loaded hydraulic servomechanism is calculated using an approximated method like the describing function. Next, a new method is introduced, namely input function is calculated which was a sinusoidal output with a settled amplitude. In this case the input function becomes an approximate sinusoidal function under certain restrictions. Handling frequency characteristics by this new method, calculation of nonlinear system becomes easier than by the first method. A few formulae developed in the paper lose the exactness in some cases of numerical calculation. The author also developed another formula which gave good result for such cases.

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It has been reported that, in the counter-current annular two-phase flow where a liquid film flows down along the wall of vertical tube and gas flows up in the core, instability of liquid film results not from reversal of flow of liquid under surface shear but from instability of the wave occurring on the surface of liquid film. From this viewpoint, the instability of the wave was treated and a correlation of critical velocity at which the liquid film becomes unstable was derived. Critical heat fluxes of the two-phase thermosyphon for pure water, ethyl-alcohol, nhexane and carbon-tetrachloride as the working fluids were correlated and comparatively good agreement was obtained. In addition, the correlation derived was compared with the previous experimental expression of a flooding velocity in a wetted column and some discussions were made.

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As has been clarified earlier in previous papers, the theoretical description of the initial process of combustion in a diesel engine may be well performed by introducing the varying-delay concept. In the present study, this theory is modified in two points in order to permit simpler prediction and wider applications. One is to determine the evaporation rate of fuel spray empirically by the measured peak cylinder pressure, and the other is to assume the existence of an unburned zone in which any heat release does not take place. The result of analysis performed for a direct-injection engine shows that the rate of heat release versus time relations are reasonably reproduced once the ignition delay is assumed to be subject to local temperature of burning zone having proper dimensions, instead of adopting spatially averaged temperature. Further, some discussions are made to clarify the effects of injection timing and of gas expansion due to piston displacement, together with a tentative explanation of misfiring.

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The measuring accuracy of scavenging efficiency by the gas sampling method depends upon mainly whether the sample represents the average composition of combustion gas or not. However, its evaluation has not been made sufficiently yet. In this paper, discussion is given about the experimental relation between the composition variation and the mass fraction of combustion gas discharged in the exhaust stroke, to evaluate the uniformity of combustion gas composition, and the following results are obtained. The measuring accuracies of the scavenging efficiency by the exhaust sampling method and the combustion chamber sampling method are estimated within errors of 1% and 2% respectively, for a sample during the last period of expansion stroke under a full operating load.

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The shape and the size of a scratched groove formed on metal surface by a single point slider, such as a cone and a sphere, have been measured in order to obtain an information for evaluating the friction force in scratching process. A special viewpoint of this study is to know the magnitude of the height of a raised ridge formed around the slider. The heights of front and side ridges were examined precisely on the scratched groove, and the effects of the cone angle and the radius of sphere on the ridge heights were well discussed. It was found that the change in shape of the slider due to metallic transfer would have an effect on the change of the ridge height. Furthermore, it became clear that the friction force increased with increasing the height of front ridge and the groove depth.

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Though several analysis of the MHD journal bearing have been reported, they are all based on magnetic fields of extreme difficulties in practical construction. This paper presents a theoretical analysis of a relatively practical case with the magnetic field perpendicular and the external electric current parallel, respectively, to its journal axis. The pressure distributions are obtained numerically and from these, the load-carrying capacity and the frictional torque are determined. Tha results obtained are compared with those of the ordinary and other types of MHD journal bearings. It is shown that the load-carrying capacity increases by the application of the magnetic and electric fields, whereas the torque is hardly affected. The load-carrying capacity is found to increase more with an increase of the external electric current than that of the magnetic field intensity. The static stiffness of this MHD journal bearing is shown to be almost of the same magnitude as that of the ordinary journal bearing.

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This paper deals with an experimental study on the MHD journal bearing, theoretically analysed in the 1st report, in a magnetic field perpendicular and an external electric current parallel, respectively, to its axis, with mercury as a lubricant. The results are compared with those of the theoretical ones, obtained in the previous paper. The bearing used is of diameter 20mm and of length 40mm. The load-carrying capacity is found to be twice that of a normal bearing under the magnetic field intensity of 5000 Gauss and electric current of 10A. The loadcarrying capacity Measured in this experiment is found to be qualitatively in agreement with the theroetical result in the region of small eccentricity ratios, though with a small difference quantitatively. However, in the region of large eccentricity ratios, the experimental results are found to be in agreement with those of the theoretical analysis qualitatively as well as quantitatively. Thus, this type of the MHD journal bearing is seen to be applicable in practice.

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