In August 2004, a pipe rupture accident occurred at The Kansai Electric Power Company Mihama Unit 3. Japan Society of Mechanical Engineers (JSME) recognized that it was an urgent problem to settle the rules on pipe wall thinning management by fluid flow. JSME enacted rules on pipe wall thinning that stipulates the basic requirements of pipe wall thinning management, considering from these situations, and in 2006, the “Rules on Pipe Wall Thinning Management for PWR Power Plants” (JSME S NG 1-2006, JSME rules for PWR) that satisfies the requirements of rules on pipe wall thinning. This JSME rules for PWR stipulates the process of inspection plan, measurement, evaluation and maintenance. This paper focuses on the technical grounds that specify the management systems, pipe components and initial FAC rate.

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This paper presents an experimental study about a possibility of a hydroelectric power station due to osmotic pressure generated between sea water and river water. The experiment is conducted by a newly constructed equipment using a spiral reverse osmotic module with membrane surface area 4.318m². The equipment can be pressured up to 0.5 MPa to avoid a generation of bubble in pure and salt water channels. Tap water and salt water are used for experiment instead of river water and sea water. On the way of tap water passage, a valve is inserted to generate a loss corresponding to a hydraulic turbine load. Using a pump, salt water is forced to circulate and its flow rate is variable. The flow rate of tap water and the pressure difference between the valve inlet and outlet are measured with varying salt concentration from 0.1wt% to 0.6wt% and salt water flow rate from 3.5 1/min to 5.01/min. In these experiments we can obtain a maximum output about 0.86W at salt concentration 0.6wt%. From these results, we had a confidence to construct the hydraulic power station utilizing osmotic pressure.

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Extrapolation methods constitute a class of acceleration techniques in which the converged solution is predicted from a series of intermediate solutions generated by the iterative method. Advantages of the extrapolation methods are simplicity and ease of the implementation in existing CFD codes. In this study, the authors apply Minimal Polynomial Extrapolation (MPE) to 2-D laminar and 3-D turbulent problems to examine the performance of MPE in unsteady flow calculation. Also Initial Extrapolation (IE), which provides a good initial guess at the start of each timestep, is tested alongside MPE. Although only six intermediate solutions are used in MPE, it realizes reasonable speed-ups : 2.88 in the 2-D calculation and 1.89 in the 3-D LES. This computational cost is far lower than that in steady calculation reported in a literature. Furthermore, the combination of IE and MPE shows larger acceleration effects than in the case of single application of MPE because the speed-ups by the joint application of the two extrapolation methods reach 4.41 in the 2-D and 2.33 in the 3-D.

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The global instability of flows behind a circular cylinder with a splitter plate is investigated theoretically to understand stabilizing effects of splitter plate on the cylinder wake. The stability analyses show that the critical Reynolds number for the global instability, which is about 46 without splitter plate, increases with the splitter-plate length. The Strouhal number of the most amplified disturbance at the critical Reynolds number is found to be not strongly dependent on the splitter-plate length. It is also found that the flow becomes globally unstable when the streamwise length of the recirculating region measured from the trailing edge of splitter plate exceeds about 2.5 times the cylinder diameter. These conditions for the onset of the global instability are the same as in the absence of splitter plate.

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In this study, mathematical formulae for evaluating scattered components of non-compact sound are summarized, and aerodynamic noise from a pantograph is predicted numerically based on the theory of vortex sound. When influence of reflection at the ground is taken into consideration in Green's functions, interference of sound waves appears and amplitude of sound pressure at an observer locating in a far field strengthens and weakens periodically depending upon its frequency, which phenomenon is similar to the experimental results. In the low frequency range, large separations occurring at the upper and lower sides of a pantograph head, lower sides of the pantograph head support and an upper frame are main sources of scattered sound propagating upward. In the high frequency range, sound seems to be produced by unsteady motion of small vortices shed from the pantograph head and the support. As for sound propagating sideward, release of large-scale vortices from the support and the upper frame in horizontal planes is responsible for low frequency noise, and longitudinal vortices rolling up along sides of the support seem to produce sound of high frequency.

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This paper describes the fluid force acting on circular cylinder row in the locking-in region. Experiments were carried out in an N. P. L. blow-down type wind-tunnel with a working section of 500mm×500 mm×2000 mm at Reynolds number of 1.60×10⁴. The cylinder was forced to oscillate sinusoidally in the lift direction. The power spectrum of fluctuating velocity in the wake behind circular cylinder row was measured to show the locking-in region in the present experiment. The time-mean and fluctuating pressure distributions were measured for a displacement in vibration. Consequently it was found that (i) the mean drag and fluctuating lift increase in the lock-in region, and (ii) the lock-in region extends for the circular cylinder row under the fluid interference due to the adjacent cylinders, as compared with those for a single cylinder.

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The characteristics of the free jet flow, which were issued from a circular pipe and affecting by the reciprocal oscillating flow, were studied in this paper. The reciprocal oscillating flows issue from two circular pipes placed at two sides of the free jet, and have the contrary phase each other. Moreover, the net flow rate of the two reciprocal flows was set to zero. The flow visualization and the PIV techniques were used to investigate the jet diffusion. As a result, it has been found that the jet diffusion is largely affected by the reciprocal oscillating flows of higher frequency. The jet diffusion is considerably promoted under the influence of the reciprocal oscillating flows. Furthermore, it has been confirmed that the jet issues with a large swing.

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The effects of orifice plate thickness t on an orifice free jet for nozzle diameter of d_o=10.0 mm and contraction area ratio of CR=0.27 were investigated experimentally. Visualized images of the water submerged jet showed large coherent vortex structure depending on the orifice plate thickness t. Hot-wire measurements were conducted at a high Reynolds number, Re=1.5 × 10⁴, for various orifice plate thickness ranged from t/d_o=0.01 to 1.5. A comparison with a pipe jet flow having a fully developed velocity profile of the turbulent pipe flow was also performed. The effect of vena contracta was apparently observed for smaller t and a similar flow behavior as the pipe jet was seen with increasing t. Sudden increase of the jet center turbulent intensity at the nozzle exit occurred for the jet of t/d_o=0.5, which has shorter potential core length and lower dominant frequency than the other jets, indicating that the flow fluctuated unsteadily at the nozzle exit. It is also found that the jet of t/d_o=0.5 entrained ambient fluid remarkably and widely spread.

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In this study, we demonstrate the small droplet transportation on vertical parallel electrodes using electrowetting and the interfacial oscillation. The transportation of water droplets, which can be applied to the droplet-based biochemical devices, is performed by applying ac voltage that ranges from 0 to 100 V_pp and from 20 to 100 Hz. The characteristic of the transportation is observed by the use of a high speed camera, and the effects of the interfacial oscillation and the dynamical contact angle on the droplet motion are investigated in detail. The experimental results show that the vertical velocity of the droplet can be controlled by changing the amplitude and frequency of applied ac voltage. In addition, the dynamics of the droplet is estimated theoretically considering the interfacial tension force due to the dynamical contact angle and the gravitational force. The predicted force and displacement of the droplet agree well with the experimental values obtained from the high speed observation of the droplet motion.

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Our previous paper ⁽¹⁾ predicted that there would be phenomena of decreasing volume concentrations of two-phase fluid containing solid spherical particles with the same specific gravity as fluid phase by flowing out through branch pipes. So the fluid was let flow through a circular pipe, and was partially let flow out through a branch circular pipe to study ratios of volume concentrations of fluid flowing out through branch pipes and those in a main pipe before branches. As a result, volume concentration ratios decreased as products of velocity ratios and diameter ratios increased. Volume concentrations in branch pipes were calculated by using potential flow models under the assumption that the fluid flowing in the layer between the wall and the plane apart a particle radius from the wall had no volume concentration of particle phase. The calculated results were found to agree with the experimental results fairly well as the prediction of our previous paper. One of the reasons why red blood corpuscles of mammals evolved into a flexible doughnut shape was considered. The shape would reduce the effects of these phenomena, and it would increase the number of blood corpuscles in capillaries. It would make it possible to use more delicate capillary systems and to evolve into higher organisms.

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The mechanism involved in the formation and subsequent rupture of cerebral aneurysm has not been clarified adequately. The aneurysm frequently appears at the flow divider where the flow bifurcates to the anterior communicating artery and the anterior cerebral artery. In the present study, the flow pattern and the wall shear stress (WSS) within the real aneurysm model having bleb are measured using PIV. On the basis of the MRI data of human cerebral artery with aneurysm, the aneurysm model is reconstructed by the optical 3D design with CAD. WSS abruptly changes along the aneurysmal wall and minimum WSS appears at bottom wall of the bleb. Particularly, WSS is small along the bleb wall. It would be associated with the degeneration of bleb wall such as the formation of thrombosis.

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The arterial branch from abdominal artery to renal artery is one of the predilection sites of atherosclerosis. In the present study, we have experimentally clarified the hemodynamic structure such as the velocity profile and the wall shear stress during pulsatile flow in a branch model where the renal artery bifurcates from the abdominal aorta. The hemodynamic structure around the renal arterial branch is characterized the gradient of wall shear stress which distinctly changes around the entrance corner to renal artery. As approaching this corner, the wall shear stress steeply increases, and after passing through this corner it suddenly decreases. Consequently, it would be physiologically suggested that the large gradient of wall shear stress is closely associated with the initiation and the development of atherosclerosis.

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The scale properties of a one-dimensional lattice model for the blood vessel with a heterogeneous part (an extended Sakanishi model) have been investigated. In the present study, from the viewpoint of mechanics, a part of the blood vessel, which has the different mechanical properties of the vessel wall, that is, a part of arteriosclerosis, prosthesis and so on, is regarded as the heterogeneous part by a generalization for the one-dimensional lattice model. The stability of the solitary wave is applied in order to obtain the reliable results by the numerical analysis of the pulse wave which propagates through the heterogeneous part in the blood vessel. As a result, we show the behaviors of the pulse wave through the blood vessel with the heterogeneous part under the condition that the scale of the pulse wave, the length of the heterogeneous part and the mechanical properties of the vessel wall are changed.

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The three-dimensional separations in a decelerating channel flow generated by the suction through a porous wall had been investigated experimentally. The decelerating flow in the straight channel in this experiment is equivalent to the flow in the straight-walled diffuser in terms of the pressure profiles. The contour of the turbulence level of the mainstream velocity shows two peak values which correspond to two corner separations. The value of cross-correlation function reaches negative peaks of large amplitude without any lag and the value of coherence gets peak value at around 0.5-2 Hz. The corner separations near the top wall and near the bottom wall keep coherent structure both with negative value of cross correlation function and with the dimensionless frequency of around 0.003-0.012, which is normalized by the inlet velocity and the hydraulic diameter of the channel.

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We studied the influence of the different wall oscillation modes on the heat transfer characteristics of a two-dimensional channel numerically. In this study, the following two channels with different wall oscillation modes were used. One is a two-dimensional channel bounded by the fixed wall and the transversely oscillating wall (channel A) and the other is a two-dimensional channel whose upper and lower wall oscillate transversely in the same manner (channel B). The fully implicit finite difference method was used for the analysis of the conservation equations and the time-dependent coordinate transformations were applied to solve the moving boundary problem. The calculated results are summarized as follows. (1) The wall oscillation takes a remarkable effect on the heat transfer enhancement in a low Reynolds number region for each channel. (2) If we must avoid the increase in the pressure loss, the channel B is suitable for this requirement compared to the channel A.

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A numerical investigation of the evaporation process of a water liquid droplet on the hot surface that has microstructure is presented. The microstructure is formed out of a uni-directionally solidified alloy, the composition of the alloy being exposed to the direction of heat flow by corrosion. The structure is considered as numerous micro-pin fins. The droplet instantly penetrated through the structure of which has a specific pin height after the placement of the drop. The kinetics of the penetration is described by R² ∝tⁿ. In the equation R is the radius of wet stain, and the power n is typically about 0.3. The evaporation process involved in the droplet penetration is classified into the four stages. The governing equations on each stage are solved numerically using the finite-difference procedure. The analysis is simplified by assuming the surface temperature to be constant during droplet evaporation. The simulated surface temperature is lower than 373 K. The results are compared with available experimental data indicating the outcome of the droplet lifetime and the droplet shape during evaporation. The computational model provides the additional information for the effects of the fin height and initial droplet diameter.

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In the present study, the flow characteristics and heat transfer of a thermo-sensitive magnetic fluid, which is a multiphase-flow material, were investigated experimentally. Heat transport systems using magnetic fluids have been proposed by several researchers, but miniature devices of this type have not yet been developed. The mini-channels considered herein have a depth of 0.5 mm, with the nominal channel width being five times the width. The channel device was constructed from a Teflon tube. The operation of the device is based on the thermo-magnetic characteristics of the fluid, a suspension of Mn-Zn ferrite particles in kerosene, the magnetization of which is known to decrease with increasing temperature. The experimental parameters were magnetic force, the position of the magnet, and the temperature of the magnetic fluid. The experimental results indicated that force convection based on the magnetic characteristics of the fluid in the mini-channel exhibited excellent cooling performance. In particular, the observed variations in the flow patterns were compared with the results of a boundary layer of the flow velocity in the pipe, which is generally known. Furthermore, it was found that the flow characteristic of the thermo-sensitive magnetic fluid was strongly dependent on the magnetic condition, such as the force and the position.

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Three-dimensional flow and thermal fields have been solved numerically for the stepped duct laminar flow for different inlet flow conditions, uniform flow and fully developed flow, focusing on the spatial distribution of the heat transfer coefficient on the bottom wall downstream the step. A larger maximum heat transfer near the side wall and a unique lower heat transfer behind the step are generated in the developed flow case while more uniform heat transfer is obtained in the uniform flow case. Particle trajectory analysis revealed that the large maximum heat transfer is produced by the intensive convection of heat caused by the downward flow near the side wall. The low heat transfer generated behind the step is strongly affected by the three-dimensional structure of the flow recirculation. Its shape is no longer two-dimensional due to the incoming fluids from the side wall and their spiral motions. In the case of developed flow, such motions are quite large and the fluids flow outside from the central part of the duct, so that the low heat transfer is generated there.

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An analogy was found between the frictional pressure drop and the heat transfer in liquid-solid circulating fluidized beds. This investigation is based on three correlations for the particle holdup, the heat transfer coefficient and the pressure drop, which were developed by the authors. When the heat transfer coefficients were expressed in terms of the modified j-factor, then a close mutual relationship was observed between the modified j-factor and the friction factor for the frictional pressure drop due to the liquid and the particle flow. The mutual relationship could be approximated by a correlation composed of the density ratio and the non-dimensional riser diameter. Heat transfer coefficient predicted from the frictional pressure drop agreed well with the experimental data by the authors, and also with existing data.

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In air-conditioning systems, it is desirable that the liquid-solid phase change temperature of a cool energy storage material is approximately 10°C from the perspective of improving coefficient of performance (COP). Moreover, a thermal storage material that forms slurry can realize large heat capacity of working fluids. Since the solid that adheres to the heat transfer surface forms a thermal resistance layer and remarkably reduces the rate of cold storage, it is important to avoid the adhesion of a thick solid layer on the surface so as to realize efficient energy storage. Considering a harvest type cooling unit, the force required for removing the solid phase from the heat transfer surface was studied. Tetra-n-butylammonium Bromide (TBAB) clathrate hydrate was used as a cold storage material. The effect of concentration of TBAB solutions on the scraping force for detachment of adhered solid of TBAB hydrate to the heat transfer surface was examined experimentally. The TBAB hydrate solids were categorized broadly into two kinds of solids. The scraping force of the TBAB hydrate solid on the heat transfer surface was different for the two kinds of the TBAB hydrate solids. The scraping force increased with the increase in the concentration of solution. It was confirmed that the concentration of solution had an effect on the scraping force required for removal of the solid.

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In recent years, much interest has been poured for the development of pulse tube refrigerators that have a simple construction and do not use the ozone depleting fluids. But, the application of pulse tube refrigerators has been limited to the deep freeze range and has not been performed in the near-room-temperature region. In the region, the performance of the pulse tube refrigerators is very low because basically the expansion work of pulse tube refrigerators cannot be recovered. In this paper, we suggest a new type of the pulse tube refrigerator that overcomes the conventional fault. It is the series type pulse tube refrigerator that has some pulse tubes connected in series. We attempted to make clear the characteristics of the series type refrigerator by employing a numerical cycle simulation based on the nodal analysis. The results prove that the series type pulse tube refrigerator has a high potential for the near-room-temperature region use.

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An inverse method for estimating radiative properties of scattering and absorbing media has been developed. This method allows us to estimate radiative properties of human skin in vivo in wide range of wavelength. In this method, a target planar medium is non-uniformly irradiated by stripe-like radiation that has passed multi-slits, and the intensity profile of radiation reflected by the medium is measured. The radiative properties, extinction coefficient and albedo, are estimated by an inverse analysis based on the intensity profile of radiation. We applied the present method for human skin, and estimated the extinction coefficient and the albedo of skin in visible range of wavelength.

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A direct ethanol polymer electrolyte fuel cell (DEFC) is an energy conversion system suitable for recycle-oriented society on the point that it uses innocuous bio-fuel, but there exists a problem that its power generation performance is low. One of the causes is the generation and stagnation of by-products in the anode-side passage. In this study, the authors have conducted numerical and experimental analyses of the liquid flow in various types of channels in the anode-side passage for estimating the pressure loss between an inlet and an outlet, and also for investigating the behavior of by-products such as acetic acid produced in the passage. It has been found that a serpentine channel with branches is preferable because the pressure loss in the channel is much lower than in a serpentine channel and also the channel is likely to discharge by-products smoothly.

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An auto-ignition process of non-homogeneous mixture was fundamentally investigated using a numerical calculation based on the chemical kinetics and stochastic approach. In the present study, the auto-ignition process of n-heptane is calculated using a reduced mechanism developed by Seiser et al. The non-uniform states of turbulent mixing are statistically described using probability density functions and the stochastic method, which was originally developed based on Curl's model. The results show that the starting points of the low temperature oxidation and ignition delay period are hardly affected by the equivalence-ratio variation, however, the combustion duration increases with increasing variance of equivalence ratio. Furthermore, the combustion duration is mainly affected by the non-homogeneity at the ignition and not very much affected by the mixing rate.

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The effects of the initiator conditions to the detonation initiation and the impulse of the pulse detonation engine were investigated. White-gasoline-air mixture in the main combustor was detonated by the initiator filled with white-gasoline-oxygen mixture. It was found that a predominant parameter to initiate the detonation of white-gasoline-air mixture in the main combustor was the overflowed white-gasoline-oxygen volume from the initiator to the main combustor. In case of the pulse detonation engine investigated, the overflowed volume of 400cm³ was required to initiate reliably the detonation of white-gasoline-air mixture in the main combustor. It was also clarified that the loss of the impulse in the case, where the fully developed detonation was not observed in the main combustor, was caused by the exhausting of unburned white-gasoline-air mixture before it burned.

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We have investigated fluid flow characteristics of filmwise condensation on vertical plates with horizontal grooves. The condensation fluid stays at the edge of the grooves due to the surface tension. The fluid starts to move, however, when the balance between the surface tension and the fluid's own weight are broken. It is found that the fluid flows downward periodically from the top part of the plate as a group. In addition, we have obtained the relation between the frequencies of the periodic flow and the degree of subcooling for two different pitches of the grooves.

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