Transactions of the Japan Society of Mechanical Engineers
Online ISSN : 2185-9485
Print ISSN : 0029-0270
ISSN-L : 0029-0270
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Volume 18, Issue 76
Displaying 1-13 of 13 articles from this issue
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  • Heat Transfer on the Surface of a Roughend Plate
    Sugao SUGAWARA, Takashi SATO
    1952 Volume 18 Issue 76 Pages 1-6
    Published: December 05, 1952
    Released on J-STAGE: March 28, 2008
    DOIhttps://doi.org/10.1299/kikai1938.18.76_1
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    This is an approximate theoretical analysis with regard to surface heat transfer on a rough surface plate. From our experimental results, we assumed that the velocity distribution of the turbulent layer in turbulent boundary layer which was influenced by the surface roughness, was expressed by the following relation. [numerical formula] Where n is a function of the surface roughness. And, by assuming the existence of the viscous layer, we obtained the velocity and temperature-distribution in boundary layer, and moreover surface heat transfer coefficient. The result is as follows : -Nu/(R6)=k2/((n+2)2)/{1+(σ-1)[n(n+2)3/(k4(n+1))Re-1]1/(n-1) Where Nu is Nusselt's number, Re is Reynolds' number and σ is Prandtl's number. This result agrees well with our experimental results performed by using air.
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  • On the Heat Transmission from an Inclined Rectangular Plate
    Ryotaro IZUMI
    1952 Volume 18 Issue 76 Pages 6-10
    Published: December 05, 1952
    Released on J-STAGE: March 28, 2008
    DOIhttps://doi.org/10.1299/kikai1938.18.76_6
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    In the present paper, the author tried experimentally to determine the heat transmission coefficient of inclined rectangular plate immersed in the free and forced streams. Two plates sizes of which are 100×100×11 and 200×200×11 respectively were taken, and the experiment was carried out over the ranges of temperature differences 0 to 100°C and as air velocities 6.40 to 23.0 m/s. From the results of experiments the eleven data have been obtained graphically, and these graphs sufficiently represent the differences due to inclinations.
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  • Heat Conduction of an Infinitely Long Hollow Cylinder due to Heat Flow from the Source Distributed Uniformly on the Outer Surface of the Cylinder (1st Report)
    Hidekichi KATAOKA
    1952 Volume 18 Issue 76 Pages 10-18
    Published: December 05, 1952
    Released on J-STAGE: March 28, 2008
    DOIhttps://doi.org/10.1299/kikai1938.18.76_10
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    An infinitely long hollow cylinder, initially at 0°C. throughout, has a heat source distributed uniformly on the outer surface and the heat source generates a constant heat flow S per unit time per unit area of the surface from the time t=0. Then the temperature θ at any point which has a distance γ from the axis of the cylinder at the time t is given by the following eq. : [numerical formula] where a, b=inner, outer radii ; k=Kelvin's diffusivity ; λ=thermal conductivity ; h1, h2=emissivities on the inner, outer surfaces ; λ1'=λ/h1 ; λ2'=λ/h2 ; βn=the n-th positive and real root calculated from the smallest root of the following eq. [numerical formula]
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  • Nucleate Boiling on Horizontal Heating Surface (3rd Report) : Effect of Dimension of Heating Surface
    Kiyoshi YAMAGATA, Fujio HIRANO, Kaneyasu NISHIKAWA, Hisamitsu MATSUOKA
    1952 Volume 18 Issue 76 Pages 19-23
    Published: December 05, 1952
    Released on J-STAGE: March 28, 2008
    DOIhttps://doi.org/10.1299/kikai1938.18.76_19
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    Already we pointed out that the important factor controlling the coefficient of heat transfer was the stirring effect of vapour bubbles in the heat transfer to boiling liquid. In this report we carried out the experiments with three hosizontal surfaces whose diameters are 7 cm, 10 cm and 14 cm respectively, and clarified that the Nusselt number at the stage of nucleate boiling was proportional to the 1/3 power of the number of vapcur columns on a heated plate independent of the diameter of the heating surface. i.e. αD/λ∝n1/3 where α=coefficient of heat transfer to boiling liquid. D=diameter of heating surface. λ=thermal conductivity of boiling liquid. n=number of vapour columns on a heated plate.
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  • Nucleate Boiling on Horizpntal Heating Surface (4th Report) : Effect of Surface Tension of Liquids
    Kiyoshi YAMAGATA, Fujio HIRANO, Kaneyasu NISHIKAWA, Hisamitsu MATSUOKA
    1952 Volume 18 Issue 76 Pages 23-27
    Published: December 05, 1952
    Released on J-STAGE: March 28, 2008
    DOIhttps://doi.org/10.1299/kikai1938.18.76_23
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    We investigated the effect of surface tension of liquids on the heat transfer in nucleate boiling by means of addition of surface active agents (saponin and sodium oleate) in distilled water. And we obtained the following relations independent of the addition of surface active agents ; α(σ/γ)-1/2∝n1/3 Δθ∝n-1/6q2/3 where α=coefficient of heat transfer. σ=surface tension of liquid. γ=specific weight of liquid. n=number of vapour columns. Δθ=the temperature difference between the surface of heating surface and boilling liquid. q=heat flux.
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  • Nucleate Boiling on Horizontal Heating Surface (5 th Report) : Effect of Surface Contamination
    Kiyoshi YAMAGATA, Fujio HIRANO, Kaneyasu NISHIKAWA, Hisamitsu MATSUOKA
    1952 Volume 18 Issue 76 Pages 28-32
    Published: December 05, 1952
    Released on J-STAGE: March 28, 2008
    DOIhttps://doi.org/10.1299/kikai1938.18.76_28
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    Vapour bubbles on metallic heating surface leave ring-shaped scale deposits due to salt slightly contained in the boiling water. These deposits promote the nucleation of vapour bubbles. If we repeat increasing and decreasing of heat flux alternately, the generation of bubbles increases due to the mutual action between bubbles and deposits, and consequently surface contamination increases. We studied effect of the contamination on heat transfer to boiling water experimentally and found relation between heat transfer and foaming ability due to the contamination. We analysed results of our experiment and derived several formulae concerning coefficient of heat transfer using the term of foaming ability. Further we compared our formulae with those obtained by other authors and pointed out the cause of wide dispersion of the values of coefficient of heat transfer.
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  • Effect of the Low Water Level on Heat Transfer of Nucleate Boiling on Herizontal Heating Surface
    Hisamitsu MATSUOKA, Kazuma URAKAWA
    1952 Volume 18 Issue 76 Pages 33-36
    Published: December 05, 1952
    Released on J-STAGE: March 28, 2008
    DOIhttps://doi.org/10.1299/kikai1938.18.76_33
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    No experimental data have been known quantatively concerning the effect of the low water level on the coefficient of heat transfer of boiling α. In preceding experiments we carried out, the normal water level was between 6 and 8 cm., and in the present experiment it is lowered from 6 to 0.5 cm., A heating surface which is made of a brass plate has diameter of 10 cm., Heat flux was changed from 8750 to 21800 kcal/m2h. The conclusions are summarized as follows : (1) There is a notable difference between the temperature distribution corresponding to the level higher than 4 cm. and that lower than 3 cm., (2) It was found that the number of vapor columns on a surface n and α remained unchanged to a certain point, and then they increased slightly with the decrease in depth. (3) Being independ of the water level, every datum could be arranged on only one curve when we take a coordinate of α vs. n.
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  • Study on a Volumetric Efficiency of Four-Cycle Engine : 4th Report, Experiments on the Valve Timing
    Tsuyoshi ASANUMA
    1952 Volume 18 Issue 76 Pages 37-42
    Published: December 05, 1952
    Released on J-STAGE: March 28, 2008
    DOIhttps://doi.org/10.1299/kikai1938.18.76_37
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    In the last paper, it is clarified theoretically that the volumetric efficiency is considerably affected by a closure angle of suction valve. However, we had no experimental results in regard to such a relation. In this paper, to prove the relation experimentally, the author made an apparatus consisting of six plate cams so as to vary the timing of suction valve stepwise, and studied a volumetric efficiency under several conditions. It is proved consequently that these results show a good agreement with the theoretical curve given in the last report. If we adjust the closure angle of suction valve according to the experimental curve, we may be able to maintain the maximum or best efficiency even when some engine conditions are changed. By some experiments on the opening angle of suction valve, it is clarified that the efficiency is little affected by it.
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  • Study on a Volumetric Efficiency of Four-Cycle Engine : 5th Report, Experimental Analysis by means of Pressure Indicators
    Tsuyoshi ASANUMA, Toshio KURABAYASHI
    1952 Volume 18 Issue 76 Pages 43-48
    Published: December 05, 1952
    Released on J-STAGE: March 28, 2008
    DOIhttps://doi.org/10.1299/kikai1938.18.76_43
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    To obtain more verifications about the effects of some engine parameters on the volumetric efficiency, the pressure-changes in suction or exhaust pipe and cylinder were taken out as changes of an electric current by means of our newly designed indicators of electro-capacity type and were recorded by an electro-magnetic oscillograph. Results : a) Whether an efficiency is good or not depends mainly on an inertia-supercharging. b) Effect of closure angle of suction valve is in the results of our study identical with that of inertiasupercharging. But the opening angle affects little on the volumetric efficiency. c) Efficiency is affected a little by the 1st or 2nd order pulsation in suction pipe.
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  • The Effective Thermal Efficiency of Free Piston Gas Turbines : Part 1. Pescara Cycle
    Fujio NAGAO, Yoshiro OTSUKA, Sachio OKANO, Tatsuo SHIMIZU
    1952 Volume 18 Issue 76 Pages 49-54
    Published: December 05, 1952
    Released on J-STAGE: March 28, 2008
    DOIhttps://doi.org/10.1299/kikai1938.18.76_49
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    In this paper, the effective thermal efficiency and other thermodynamical factors of the Pescara gas turbine are calculated on the following assumptions : 1. The miscellaneous losses in irreversible changes are as little as possible. 2. The factors prescribing them are constant. 3. In the engine cylinder, combustion occurs only under constant volume and pressure. 4. The highest pressure and compression pressure are constant. As the results of calculations, the thermal efficiency has been proved to be very high even at low gas temperatures, for instance, 41% under the following conditions, turbine adiabatic efficiency 85% pressure ratio in compressor cylinder 5 turbine inlet temperature 364°C excess air factor in engine cylinder 1.6
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  • The Thermal Efficiency of Free Piston Gas Turbines
    Fujio NAGAO, Yoshiro OTSUKA
    1952 Volume 18 Issue 76 Pages 54-60
    Published: December 05, 1952
    Released on J-STAGE: March 28, 2008
    DOIhttps://doi.org/10.1299/kikai1938.18.76_54
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    The free piston gas turbine will be classified into several cycles by the method of heating the compressed air, the fundamental cycles of wich are Pescara, constant pressure combustion, regeneration and regenerative constant pressure combustion cycle. By analysing the reversible air cycles of them thermodynamically, the relations among thermal efficiency and principal factors were obtained. The thermal efficiency of the three cycles except Pescara can be determined by the three factors, namely, thermal efficiency of engine cylinder, pressure ratio in compressor cylinder and ratio of turbine inlet temperature to the atmospheric one. While the efficiency of Pescara cycle can be determined only by arbitrary two factors among them and is equal to that of a Sabathe cycle which has the same max. pressure, degree of explosion and cut-off ratio as the engine cylinder of Pescara and operates on the atmospheric pressure. Assuming that the efficiency of engine cylinder is equal to 60% and the ratio of turbine inlet temperature to the atmospheric one 3, the max. thermal efficiency and the pressure ratio for each cycle were calculated as follows : [table]
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  • The Stress of Boiler Flat Endplate (Part 5) : The depth of flange of manhole in flat endplate
    Hideo YAMANAKA
    1952 Volume 18 Issue 76 Pages 60-66
    Published: December 05, 1952
    Released on J-STAGE: March 28, 2008
    DOIhttps://doi.org/10.1299/kikai1938.18.76_60
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    Where a flat plate is flanged for strengthening it at a manhole, the total depth (h) of the flange is usually calculated as follows ; h=√(tW) or h=3t where t is the thickness of the plate in mm., and W is the minor axis of the hole in mm. The values calculated show much difference between them and "which is suitable has not been decided. In this paper, the writer has discussed theoretically that the depth of the flange is affected by the stresses and the deflection of the endplate and proved it by experiments.
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  • The Stress of Boiler Flat Endplate (Part 6) : The stress of a flat endplate supported by the shell plate and the flue tube eccentrically fitted
    Hideo YAMANAKA
    1952 Volume 18 Issue 76 Pages 67-72
    Published: December 05, 1952
    Released on J-STAGE: March 28, 2008
    DOIhttps://doi.org/10.1299/kikai1938.18.76_67
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    To solve the question on the strength of the flat endplate supported by the shell plate and the flue tube eccentrically fitted as a Cornish boiler and especially without gusset stay, the writer treated it as follows : Assuming the stresses and deflections along a radius drawn from the centre of the inner circle to an intersecting point by a concentric arc of the inner circle and the outer circle as those of a flat plate supported by two concentric circles, the writer solve it. The above treatments are applicable within the range of the dimensions of the usual Cornish boiler. The results of the experiments carried out on a model confirmed reliability of the writer's solution, and the writer also introduced a method in designing the eccentric flat endplate.
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