A hot spin tester has been designed in order to carry out the investigation of the strength and creep properties of high temperature alloys for the gas-turbine rotor. The stress for design of the machine has been laid upon the accurate measurements and controls of the test conditions. The maximum dimensions of the specimen put to test are 500 mm in diameter and 100 mm in thickness. The test specimen, mounted on a flexible shaft with its axis vertical in a vacuum furnace, is driven by a geared universal-motor and its speed is controlled automatically by means of an electric circuit. The maximum speed for long time test is 25000 r.p.m. The uniform specimen temperature up to 1000°C can be attained by the electric furnace. The radial displacement at 70, 140 and 210 mm radii of the disk can be measured with the accuracy of 0.01 mm by the optical apparatus designed specially for the purpose, when the disk is rotating at high speed and high temperature, so that not only plastic and creep strains but elastic ones can be obtained with a high accuracy. For bursting tests of small disks, such as small turbo-charger rotors, an air-turbine attachment has been designed and put to operation, covering the speed range up to 100000 r.p.m.

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The mechanical properties of a low carbon steel have been very much improved by the help of rapid quenching, such as induction hardening. Low carbon steel has enough ductility to be worked in cold state even after being quenched. The mechanical properties are more improved by cold working after quenching than by quenching only. The author tried to get a high tension steel wire of low carbon content by making a practical application of a low carbon steel to give the excellent properties. The mechanical properties of a low carbon steel wire are very much affected by the factors, such as the temperature and speed of heating and cooling. In this paper the investigation of the effects of these factors on the mechanical properties of a low carbon steel wire is described. From the results the author comes to the conclusion that a high tension steel wire of low carbon content may be used in practice instead of a high carbon steel wire or piano wire.

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In order to make clear the influence of size of blanking diameter on the shearing resistance and accuracy of dimensions of products, the authors performed circular blanking tests of 2 to 50 mm diameter with a mild steel sheet, a copper plate and an aluminium plate 0.2 to 1.0 mm thick. As a result of this experiment, it has been shown to be convenient to classify the blanking process into 2 kinds according to the ratio of die hole size to metal thickness : i.e. narrow punching process and general blanking process.

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Assuming that thread formation by rolling is a kind of indentation which is continuously and repeatedly impressed on the blank by a die, the writer has measured the relation among the indentation of a die which is statically impressed on the blank, the grooves cut on the blank by a rolling die and the height increase of screw threads generated by the rolling die aling the grooves of the threads, and introduced a formula with consideration of the relations between the rolling pressure and the number of rotations of the die required for the complete formation of the threads. This paper explains the thread rolling of a hollow tube without a mandrel under a proper rolling pressure, and shows how the abovementioned formula coincides with experimental results.

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An experimental study on the effect of the tip shape at entrance of the impeller vane of the centrifugal pump on cavitation was conducted by the writer with a vertical type centrifugal pump. The experiments were carried out on three different types of tip shape. In each case, the head-capacity curve, the static pressure distribution on the surfaces of the vanes near the entrance tips and the modes of cavitation occurrence were measured. Results of the experiments are as follows : (1) At the shockless entry, there are more chances of cavitation for the round tip vane than for the other type vanes. For the sharp tip vane no cavitation occurs in the experiments. (2) Except at the shockless entry, in spite of the discrepancy of the vane tip shapes, incipient cavitation occurs in each vane at the same relative velocity and suction head. And those facts mentioned above are considered to be natural from the pressure distributions on the vane surfaces.

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From the view point of utilization of coal ashes, the production of various by-productsash-cement, ash-wool and fused phosphate-is undertaken through a small test furnace of a slag-tap firing type. Further described here are the test results and some consideration about the industrial procedure in the future. These by-products, in their qualities, are comparatively inferior to the like products on the market. They are, however, economically valuable from the point of utilizing the very wastes-coal ashes-as raw materials. The purpose of applying both sintering and quality-control furnaces for the production of cement and wool lies in eliminating the trouble caused by the load variation unavoidable in the practical boiler operation, and also lies in improving the quality of the by-products themselves. These auxiliary-furnaces, in the present level of development in the fields of industries, are considered the very useful measures for the realization of them in their industrial scale.

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In the industrial heat-exchangers, there are many cases of unsteady heat transfer in the hydrodynamic entry length with temperature distributions of pipe-walls along the axial direction of double pipes and the pressure-drop from the inlet to the outlet, and in the atomic reactors (LMFR), the heat generates from the inside of the fluid. Therefore, in these cases, the research of unsteady heat transfer generating heat from the inside of the fluid is necessary. In this paper, theoretical solutions of the unsteady heat transfer in the hydrodynamic entrance length of vertical double pipes are made. In these solutions, such cases of unsteady heat transfer in the hydrodynamic entry length of vertical double pipes are treated that the heat generates from the inside of the fluid, free convection and laminar flow coexist at the same time, the pressure drops from the inlet to the outlet, and arbitrary temperature distributions of pipe-walls vary in the axial direction. In the solutions, the finite Hankel transform, the finite Fourier transform, the Laplace transform and Bessel functions are used. But, there is not a case of such an experiment. Theoretical solutions are reduced to the steady heat transfer and compared with experiments.

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There are many measuring methods of thermal conductivity of materials, all of which, however, are the methods conducted in stationary state. In this report, we revolved a wire ring at a certain velocity, heating it by a stationary spot heat source, and measured the thermal conductivity of the material by the relation between the measured value of periodical temperature distribution and that of the theoretical equation, which is analyzed as a problem resulting from the heat source moving along the ring circumference. An advantage of this method is that during measurement the coefficient of heat transferred from the surface of a material can be easily kept constant. Moreover, the availability of this method was ascertained by the experimental results on some materials.

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In order to clarify the fundamental characteristics of liquid atomization by means of a rotating nozzle, the behaviours of a water jet were observed by high speed photography, and on the other hand investigations of the variation of sizes of droplets produced from the jet were made, varying the atomization conditions with the nozzle diameter from 0.4 to 1.2 mm, the rotating diameter from 10 to 20 cm and the flow rate from 0.1 to 6 cm³/sec. It was found that the modes of disintegration were divided into five typical forms, and that each of them showed its own characteristic in the variation of droplet sizes. Detailed considerations are made on them. Finally the maximum diameter of the droplets was compared with the mean diameter.

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The sizes of droplets produced from a continuous liquid jet depend mainly on its thickness. This paper, deals with the contractions of smooth liquid jets discharged from a fixed and a rotating nozzle through acceleration and surface tension. Formulae for the thicknesses of jets are derived theoretically, and the condition is found under which the influences of physical properties of liquid on the thickness become negligibly small. Relationship between the cases of a fixed nozzle and a rotating one is also discussed. The values computed from the formulae show a good agreement with those experimentally obtained. The results may also be applicable to filamentation of viscous liquid by means of a rotating nozzle.

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This investigation is concerned with the rates of heat transfer from the working gases to the combustion chamber walls of the internal combustion engines. The test engine used is a four stroke spark-ignition engine with a water cooled single cylinder, bore×stroke being 114.3×140 mm. On the basis of author's experimental results, it was ascertained that the coefficients of heat transfer in this engine agreed well with those which were calculated by Eichelberg's formula [numerical formula] in the expansion stroke, but did not so well in the compression stroke. Law of similarity has been rarely applied to the problems of periodic heat transfer in the internal combustion engines, but recently Karl Elser developed this research. In the present report, improving Elser's method, the relation between the dimensionless groups was found as follows, [numerical formula] where Δs : entropy change C_p : specific heat under constant pressure change θ : crank angle

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A great many theoretical researches are reported on the periodic heat transmission in the internal combustion engines. Many of them discuss the problem only from the point of view of heat conduction in the solid wall, but there are few reports on the theory of heat transfer in the working gases. H. Pfriem and K. Elser have derived the energy equation of the gases especially in the boundary layer near the cylinder wall and solved it. But they have calculated only the heat transferred from the gas space to the wall under the condition that there were not any heat sources in the gases and the adiabatic compression and expansion were repeated. It is the object of the present paper to introduce the term of heat quantity in the energy equation by applying the conception of the polytropic change. By this means the heat flow from the gases to the wall of combustion chamber can be calculated when the gas cycle is quite similar to the spark-ignition engine. In the latter part of the present report, the numerical calculation is made, and the calculated results are compared with the experimental results.

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In order to investigate the effect of the timing of swirl creation on the combustion process in a Diesel engine, varying amounts of fuel were injected from two sets of fuel-injection equipments into the main and auxiliary combustion chambers respectively at different timings. A swirl was created in the main chamber by an outflow of gas from the auxiliary chamber. Swirl creation prior to the fuel injection into the main chamber brings a small improvement on the combustion state, but is accompanied by an unfavorably rapid and high pressure rise. Swirl creation after ignition is more effective in shortening the after-burning of fuel, as ascertained by the high-speed photography. When fuel is injected into the auxiliary chamber after TDC, the noiseless and smokeless combustion with fairly low peak pressure is materialized without the expense of fuel consumption.

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A small type Diesel engine is driven by a motor with various μU/W values, then water steam is added to the inlet air, and exhaust gases of the other combustion engine is sucked in. The weight loss of the piston-rings is measured, and the following results have been obtained. (1) When the oil film is thin to a certain extent and at the same time, the combustion products attack on it, the wear is increased greatly ; however, if one of these conditions is absent, the wear becomes very small. (2) When the exhaust gases of the fuel with high sulphur content are sucked in, and the cooling water temperature is low, the engine is corroded very violently by the condensed water, containing the sulfuric acid.

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A small type Diesel engine is operated with the fuel containing various sulphur compounds and under various engine conditions. These tests show that (1) the top-ring wear is large owing to the fact that it is surrounded with the combustion products, so when the gas-tightness of the top-ring is inadequate, the 2nd-ring wears in the same order ; (2) the more sulphur is contained in the fuel and the lower the temperature of cooling water goes down, the more the corrosive wear increases. The cylinder surface is corroded by the condensed liquids of the engine exhaust gas ; containing much SO₃, the liquid easily penetrates into the lubricating oil, and attacks the metal surface. Chemical analysis shows that SO₃ presents itself so much in the exhaust gas, that the ratio SO₃/SO₂ is about 10%.

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