[en] The prediction of fatigue strength for teeth root in gear mechanism, so far, has been calculated by normal distribution with 50% reliability consideration. In this study, the results of teeth root break in evaluated in more realistic sense based on Weibull distribution approach in the region of finite life. By this approach the so called fatigue strength diagrams were obtained with specified reliability level. (author)

[en] A numerical analysis has been performed for turbulent flow developing in 90deg bend with weakly swirling flows. The ratio of bend mean radius of curvature to diameter is 2.0 and straight duct of 25 and 35 diameters are attached to the inlet and outlet of the bend, respectively. In numerical analysis, an algebraic Reynolds stress model is adopted in order to predict precisely the swirling flow induced by anisotropic turbulence and boundary-fitted coordinate system was introduced as the method of coordinate transformation. Mean velocity in axial direction, secondary flow generated by interaction between pressure gradient and centrifugal forces, pressure distributions in bend and turbulent energy distribution are compared with the experimental data. The present method could predict well the stream wise mean-velocity, i.e. maximum mean-velocity located inner wall at bend inlet and low velocity region produced near inner wall at bend outlet. As for the comparison of secondary flow, acceleration of secondary flow near upper wall, deceleration of it near lower wall at bend inlet and a pair of asymmetrical vortices observed in bend tube could be reproduced by an algebraic Reynolds stress model. Moreover, numerical results show that characteristic phenomena of turbulent energy are reproduced by the present method although agreement between both results is certainly not perfect in all detail. (author)

[en] The principal objective of this analysis is to verify that the newly developed bottom/side lift gantry concept continues to be a suitable design concept for the current Monitored Geologic Repository (MGR) design. This analysis includes an examination of the waste package (WP) transfer operation at the emplacement drift transfer dock. In addition, this analysis verifies that the gantry is compatible with the WP transporter, which has been redesigned to handle WPs sitting on pallets (CRWMS M and O 2000a). The scope of this work is to examine the existing analysis and to determine what, if any, modifications to the analysis may be required as a result of additional requirements imposed by the EDA II concept. Then, a revision will be made to the conceptual design accordingly. The analysis will also be revised to show the approximate sizes and locations of the electrical equipment and control cabinets, and to take into account the weight of that equipment in the total gantry weight. The analytical portions of the analysis are revised, as required, to address changes resulting from modifications to the conceptual design or from changes in classification and/or SDD requirements. Finally, the revised conceptual design is evaluated to verify that it continues to be a suitable method for handling the WPs within the emplacement drift

[en] The diverter surface of fusion reactor and a target surface of accelerator are heated by high energy radiation. A rotating annular flow by a rotor are used to enhance heat transfer characteristics, because Taylor vortexes are formed in such flow. It is expected that a pulsating pressure by a rotor with gear surface increases CHF. In this study, heat transfer coefficient and CHF were investigated in various rotation velocities and subcooling. (author)

[en] The Forced-Convective film-boiling heat transfer was investigated experimentally focusing on turbulence on liquid phase in high Reynolds number region and the mechanism of the critical condition on the heat transfer characteristics. Quenching tests of a vertical-long-thick cylindrical pipe were conduced for subcooled R-113 near 0.1 Mpa. A range of bulk-liquid velocity was 0.1 to 11.4 m/s. The characteristics of the heat-transfer coefficients for the liquid velocity above 2.4 m/s were qualitatively close to the Dittus-Boelter type correlation based upon the turbulent flow. The critical condition was about Re₁=3.4 x 10⁴ for R-113. Furthermore, it was noticeable that thickness of vapor film in the film boiling at the critical condition was just as that of the viscous sublayer in turbulent boundary layer of the bulk liquid. (author)

[en] The averaged tangent flow stress and heat flux on the wall, averaged by the oscillations period, as well as the Nusselt numbers are studied for a pulsating turbulent flow in a round tube. Calculations are accomplished on the basis of the developed turbulent transfer models including the relaxation equations for the turbulent stress, heat flux and viscosity. The applicability of the model by means of comparison with the experimental data is indicated. The influence of the performance parameters, notably Stokes, Reynolds and Prandtl numbers, oscillation amplitude of the velocity averaged by the cross section, and also the type of the thermal boundary conditions inside the wall on the heat exchange and resistance is considered. The peculiarities of these values during the pulsating flow rate, similarity and difference between the regularities of change of hydrodynamic and thermal characteristics are explained

[en] The problem on the vapor bubble growth rate in uniformly overheated liquids during saturated boiling is solved. It is assumed that vapor temperature in a bubble is constant and equal to saturation temperature. The formula for vapor bubble growth velocity both by boiling in the volume of overheated liquid and by boiling under the conditions of saturation on the plane surface and thin wire is obtained. The errors of the above-mentioned formulae are analyzed on the basis of the experimental data

[en] One of the possible interpretations of empiric ratios proposed earlier for description of evaporation kinetics into the atmosphere of thin liquid layers placed on impermeable sublayer, preheated up to constant temperature, is considered. Such a way of heating makes it possible to achieve high superheating above the temperature of the liquid-vapor equilibrium phase transition and to approach the spinodal vicinity. Introduction of corrections in the calculational ratios for pre-spinodal limitations is proposed

[en] Interfacial stresses at two-material interfaces and initial displacement field over the entire domain are obtained by modifying the potential energy functional with a penalty function, which enforces continuity of the stresses at the interface of two materials. Based on the initial displacement field and interfacial stresses, a new methodology to generate a continuous stress field over the entire domain has been proposed by combining the modified projection method of stress-smoothing and Loubignac's iterative method of improving the displacement field. Stress analysis is carried out on two examples made of dissimilar materials: one is a two-material cantilever composed of highly dissimilar materials and the other is a zirconium-lined cladding tube made of slightly dissimilar materials. Results of the analysis show that the proposed method provides an improved continuous stress field over the entire domain, and accurately predicts the nodal stresses at the interface, while the conventional displacement-based finite element method produces significant stress discontinuities at the interface. In addition, the total strain energy evaluated from the improved continuous stress field coverages to the exact value in a few iterations. (author)

[en] Many nuclear power plants have experienced unscheduled shutdown due to the leakage of steam generator tubes. The leakages are normally due to the crack, possibly stress corrosion cracking(SCC) near the tube expansion at the top of tubesheet or at the tangential point of the row -1 U-bend region. The conventional eddy current technique, which makes use of a differential bobbin coil, has been found to be inadequate for the early detection of SCC. During the in-service inspection, therefore, it is a general practice that the rotating pancake coil (RPC) is used for detecting the cracks. Even in using RPC, however, it is difficult to determine the depth of the cracks quantitatively. This paper attempts to determine the detectability and sizing ability of RPC technique for axial or circumferential cracks at the tube expansion region. The simulated cracks with various dimensional were fabricated by electro-discharge machining (EDM) method. Experimental results are discussed with theoretical calculations. (author)