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内田 竜朗, 大友 文雄, 福武 英紀, 伊東 正雄, 鹿目 浩正, 奥野 研一
2013 年 79 巻 808 号 p.
2538-2542
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
This paper describes a gas turbine inlet air cooling system using high pressure spray nozzle. Scale model inlet duct is manufactured within water spray of inlet fogging system, and many testing was conducted on the condition of same level of actual velocity with inlet duct at site. As testing results, droplet size finally reduce to SMD 80
μm at 1st blade leading edge. Next, water spray adjusting actual attack to blade is provided to test piece of same material with actual compressor blade, and weigh is measured at every constant time period for getting averaged erosion depth. As a result, it is concluded that erosion at leading edge of 1st compressor blade is predicted to be approx 1.2mm at maximum per 10 years less than acceptable limit of depth, and it may have no need for maintenance of blade replacement and so on in 10 years.
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小林 謙一, 永峰 陽介, 藤岡 照高, 駒崎 慎一
2013 年 79 巻 808 号 p.
2543-2547
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
Small Punch (SP) Creep test is a new semi destructive testing methodology where a very small specimen is required to examine creep properties. The size and the volume of SP creep specimens are much smaller than those of conventional uniaxial creep specimens. This testing methodology has been recognized as a practical procedure to know residual creep lives of high temperature components. Employing a part of aged boiler tubes made of STBA24 used for about 140,000 hours below 500°C, the SP and the uniaxial creep tests were conducted at 650°C in air and Argon gas to study the relationship between the SP and the uniaxial creep tests, and to investigate the influence of testing atmosphere on test results. SP creep rupture lives were nearly the same regardless of both sampling area and the testing atmosphere. Ratio of an applied load in the SP creep test to an initial stress in the uniaxial one was about 2.1mm
2, and a little increased with the rupture life.
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永井 二郎, 計 縈贏, 高野 武史, 出所 敏美
2013 年 79 巻 808 号 p.
2548-2551
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
This study aims to develop a heating assist system for liquid tanks by using shallow geothermal energy via a new type of heat pipe named Bubble-Actuated Circulating Heat pipe (BACH). In this system, BACH transports heat from shallow underground (temperature remains constant at around 15 °C in Fukui) to the liquid of caustic soda solution (49 wt%, freezing point is about 5 °C) preserved in the tank. From a previous simplified small-scale experiment, we concluded that BACH could warm the liquid to some extent in winter. In this report, experimental results of field tests are demonstrated where 10 m
3 tank equipped with an electric heater as an auxiliary heater was tested and five sets of BACH were installed. As a result, this system could warm the liquid at about 7 °C only by BACH without electricity under the experimental conditions tested.
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高橋 武彦, 佐藤 好希, 伊藤 一志, 森 英明
2013 年 79 巻 808 号 p.
2552-2556
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
A vibration mill using cog-ring media, which replaces the ball medium in a conventional vibration mill with a cog-ring medium, was developed to achieve high-impact pulverization of lignocellulosic biomass for producing bio-ethanol. Japanese cedar powder pulverized by the vibration mill using cog-ring media showed that saccharification efficiency in enzymatic saccharification of Japanese cedar powder of greater than 70% was reached based on holocellulose at tube test. For this study, the effect of agitation speed on enzymatic saccharification was investigated using a pulverized Japanese cedar powder. Results showed that the saccharification efficiency at 10% solid concentration increased concomitantly with decreasing agitation speed until 30 rpm. The best yields of 77% at 1 L and 75% at 3 L were obtained at 30 rpm agitation. Moreover, relation between Reynolds number for mixing and saccharification efficiency was discussed to find good index for enzymatic saccharification by agitation.
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鈴木 正己
2013 年 79 巻 808 号 p.
2557-2561
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
Computational fluid dynamics (CFD) modeling and experiments have both advantages and disadvantages. Doing both can be complementary, and we can expect more effective understanding of the phenomenon. CFD is generally difficult to obtain reliable results over the wide range when compared with the experiment. However, it is possible to obtain useful detailed results in any condition based on verification using the experimental results. Moreover, experiments are not necessarily deliver correct results for any arbitrary condition due to limitations of the experimental equipments, the measurement errors and the problems with measurement systems. In this paper, the efficiency of a wind turbine is proposed, and the performance can be compared with the other turbomachineries, which is different from the traditional wind turbine factors, that is, the power coefficient, the torque coefficient, the thrust coefficient and so on. The characteristics of wind turbine are evaluated by combining simple approximate analysis based on wing section, CFD simulations and experimental results.
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若嶋 振一郎, 宮下 幸雄, 山田 昇, 高橋 勉, 大塚 雄市, 山崎 渉
2013 年 79 巻 808 号 p.
2562-2566
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
In this report, numerical analyses of performances of prototype Mg-alloy micro vertical axis wind turbine (VAWT) were conducted. It has three wings with usual NACA0018 wing section. Typical Reynolds number based on the wind speed and the wing chord length were set around 3.3×10
4 with consideration of use as a portable-type micro VAWT system for engineering educations. In such low Reynolds number cases, somewhat different way of design would be required because of flow separation and reattachment, short bubbles etc. We also examined a torque variation generated from the wings using 3-D unsteady CFD analysis and compared the results and flow patterns for higher performance.
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原 豊, 住 隆博, 井上 尚子, 田中 華奈
2013 年 79 巻 808 号 p.
2567-2571
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
This study carried out CFD (Computational Fluid Dynamics) analyses to build up a database of aerodynamic characteristics of cambered blades like NACA 2518, NACA 4518, and NACA 6518 in order to use it for performance prediction of vertical axis wind turbines (VAWTs). The results showed that, at the neighboring range of zero-angle of attack, the lift coefficients uniformly increase and the moment coefficients uniformly decrease with increasing the Reynolds number. The approximate equations for these dependences on Reynolds number are proposed in the present study. Using the obtained aerodynamic database, performances of virtual small scale VAWTs with cambered blades were predicted by Blade Element Momentum (BEM) method with Double-Multiple Streamtube (DMS) model. Increase in camber of concave-in configuration (usual camber) extends the power curve toward high tip-speed-ratio region although the maximum power decreases. On the contrary, increase in camber of concave-out configuration (inverse camber) diminishes the width of the power-curve peak.
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本多 正明, 武居 昌宏, 都 徳照
2013 年 79 巻 808 号 p.
2572-2576
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
The flow characteristics of a new hybrid vertical axis wind turbine which has advantages of the drag type and the lift type wind turbine have been investigated by the conditional sampling PIV. The experimental apparatus is constructed using the PIV measurement system with a conditional sampling device and a new hybrid vertical axis wind turbine model installed in a circulating water channel. The measured velocity vector fields have clarified that the low velocity regions are inside of rotating turbine and the downstream of it. The influences of the low velocity regions on the torque generated by the blades are investigated by the tangential forces calculated by the pressure distribution around the blades calculated from the velocity fields measured by PIV. And, it has been clarified that the tangential forces of the blades in the low velocity regions are small. Moreover, it has been clarified that the tangential forces generated by the rotating hybrid blades are sourced not only by the lift but also by the drag in the low tip speed ratio case. Therefore, the effectiveness of the hybrid blade for the new vertical axis wind turbine has been demonstrated.
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河野 孝昭, 東 大輝, 木綿 隆弘, 木村 繁男, 小松 信義
2013 年 79 巻 808 号 p.
2577-2581
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
This paper illustrates the results of a wind tunnel experiment for the measurement of aeroacoustic noise from a straight-bladed vertical-axis wind turbine (VAWT). The measurement of the sound pressure was conducted by using microphone arrays composed of 16 microphones. At the side of the VAWT where the relative wind velocity that acts on a blade becomes maximum, it was observed that the existence of the blades led to a broadband sound from 400 Hz to 6300 Hz. In addition, the possibility was confirmed that aeroacoustic noise from blade tips at 1250 Hz become more prominent with an increase in the tip speed ratio and in the blade pitch angle amplitude. Above the VAWT, it was found out that the horizontal position where the sound level was the highest varied with the tip speed ratio, blade pitch angle amplitude and eccentric angle.
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武藤 崇史, 水澤 竜也, 森 昌史, 荒木 拓人
2013 年 79 巻 808 号 p.
2582-2586
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
Solid Oxide Electrolysis Cells (SOECs) can be used for hydrogen generator systems. In this study, two types of SOECs which have different operating temperatures, 850°C and 650°C, were treated. For 850°C-type cell, measurements of current density-voltage characteristic and current efficiency were carried out and the data of 650°C-type cell were obtained from the previous report. For 850°C-type cell, the voltage at 0.4 A/cm
2 was 1.20V and the current efficiency was approximately 100%. With the experimental values, cycle calculations for SOEC system models with production capacity of 300Nm
3/h were carried out. At a rated operating point of 0.4A/cm
2, the exergy efficiencies depending on each source of supplied energy were discussed. When all energy was supplied by electricity, the exergy efficiencies were 80.2% for 850°C-type system and 80.5% for 650°C-type one. When heat of 110°C was supplied, efficiencies were 89.2% for 850°C-type system and 90.5% for 650°C-type one. When heats of 110°C and 850°C or 650°C were supplied, they were 91.4% for both systems. The efficiencies were also discussed at various electric supply loads. At the load area< 950kW, 650°C-type system had higher efficiency than that of 850°C-type one. On the other hand, at the load area> 950kW, the efficiency of 850°C system was higher.
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平田 勝哉, 片桐 康誌, 前田 毅, 篠木 俊雄, 舟木 治郎
2013 年 79 巻 808 号 p.
2587-2591
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
Supposing the design of household-use-scale ethanol-steam-reforming reactors, the authors conduct experiments with Cu/ZnO/Al
2O
3 catalyst. More specifically, the authors investigate the influences of liquid-hourly space velocity
LHSV upon concentrations such as
CH2,
CCO2,
CCO and C
CH4 and the influence of
LHSV upon the ethanol conversion
XC2H5OH, in a wide range of
LHSV at several
S/C's and at several
TR's. To conclude, all the concentrations are close to the theory of Shinoki et al. (2011) except for the case at high
LHSV (> 0.6 h
-1) and low
TR (= 520 K). To settle the inconsistency of this exceptional case, the authors propose a new theory using some chemical reactions related with acetaldehyde CH
3CHO. By introducing both ethanol-decompose-reaction ratio
α and the chemical-equilibrium performance measure
β into this new theory, we can settle the inconsistency. Furthermore, the authors discuss the influences of
S/C and
TR in addition to
LHSV.
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末包 哲也, 岡田 雄大
2013 年 79 巻 808 号 p.
2592-2596
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
We experimentally investigated the effect of capillarity and buoyancy on non-wetting phase saturation after the drainage. Distributions of the NWP in porous media have been visualized by mean of microtomograhy at a pore-scale for a supercritical CO
2 and water system. In the case of the upward injection, gas saturation is low compared with the upward case, because the capillary fingering is enhanced by buoyancy. Gas saturation increases with the capillary number because of the pressure gradient along the porous medium. In the case of the downward injection, the fingering is suppressed by buoyancy. As a result, the high gas saturation is achieved over the wide range of capillary number. The gas saturation decrease slightly with the capillary number because of the instability associated with the injection flow rate. The combined dimensionless group of Bond number and capillary number is introduced to correlate with the gas saturation obtained for the nitrogen and water system.
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清水 喬暢, 小倉 裕直
2013 年 79 巻 808 号 p.
2597-2601
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
From the viewpoints of energy saving and environmental impacts, we have been studying Chemical heat pumps (CHP) especially focusing on using calcium systems. The CaSO
4/ CaSO
4·1/2H
2O gas-solid reversible reaction is used to store around 393K and release hot/cold heat. In this paper, we studied the energy efficiencies of CaSO
4 CHP in heat enhancement mode for commercial use with various cases. As a result, it is found that the stored heat is converted/released at 353K /278K level hot/cold heat. The CaSO
4 CHPs could be commercially used for wider operating temperature ranges in appropriate heat source conditions. Furthermore, the thermal efficiency was obtained to be more than 1.3, and the coefficient of performance (COP) was obtained to be about 18. It means the CaSO
4 CHPs could be more efficiently than other types of heat pumps
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大内 崇史, 高田 翔, 濱本 芳徳, 森 英夫, 江藤 淳朗
2013 年 79 巻 808 号 p.
2602-2606
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
Enhancement of adsorption/desorption rate in an adsorption heat exchanger is effective to downsize adsorption chillers and desiccant systems. Exothermic/endothermic phenomena during adsorption/desorption decrease with the adsorption/desorption reaction rate, so that it is necessary to improve the heat transfer performance of adsorption heat exchanger. Thin film adsorbent coated on the plate is promising to enhance the heat transfer, because it has large contact area on the plate. In the previous study, it was clarified that the heat transfer performance of a porous alumina thin film as an adsorbent coated on an aluminum plate was greater than that of conventional particle packed bed of activated alumina. In this study, the adsorption equilibrium and the desorption rate of porous alumina thin film were measured. The parameters in BET equation were determined and Polanyi's potential theory was examined. In addition, effective diffusivity of water vapor in desorption process was formulated.
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Feng SHAN, 藤城 敦史, 恒吉 達矢, 伊藤 高啓, 近藤 昌也, 辻 義之
2013 年 79 巻 808 号 p.
2607-2611
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
Flow Accelerated Corrosion (FAC) is one of the issues to be noticed considerably in plant piping management. For the integrity and safety of the plant, the wall-thinning and thinning rate due to FAC should be predicted, and we hope to construct the model to predict the wall thinning rate. We have studied FAC from the view point of flow dynamics. The mass transfer coefficient and the velocity fluctuation are measured simultaneously behind the orifice in pipe. The former is obtained by the electrochemical method and the latter is PIV measurement. Space-time correlation and conditional sampling technique reveal that the large scale motions play an important role for the mass transfer rate at the wall and there is a time lag between mass transfer and velocity fluctuations. They may be useful for the model to evaluate the wall-thinning rate.
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恒吉 達矢, Feng SHAN, 田中 鉄平, 近藤 昌也, 伊藤 高啓, 辻 義之
2013 年 79 巻 808 号 p.
2612-2615
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
In the prediction of Flow Accelerated Corrosion (FAC), quantitative prediction of wall mass transfer coefficient or the geometric factor defined as the ratio of wall mass transfer coefficient in the piping systems (such as orifices, T-junctions, elbows) to that in a straight pipe is very important. Because of the entrance effect, the geometric factor based on point electrode is smaller than that obtained from the case in which the whole area is active. We correct the mass transfer coefficients measured by point electrode downstream of an orifice, and the corrected values are compared with previous results. The maximum values of geometric factor downstream of an orifice are expressed as a function of orifice-to-pipe diameter ratio.
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江原 真司, 久保 達也, 橋爪 秀利
2013 年 79 巻 808 号 p.
2616-2620
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
Flow visualization experiment and accelerated pipe wall thinning experiment were conducted by applying a swirling flow generated by a piping configuration, three-dimensionally connected dual elbow, to the inlet flow condition of a pipe orifice to investigate pipe wall thinning downstream of an orifice appearing due to the combination of swirling flow and orifice. The flow downstream of the orifice was curved by the action of the swirling flow, and the channel wall where the flow turned off toward underwent a large amount of wall thinning. Profiles of turbulent quantities, such as turbulent kinetic energy and Reynolds shear stress, were compared to those of amount of pipe wall thinning. It was found that the profiles of Reynolds shear stress showed good agreement with those of pipe wall thinning in the case for a large amount of that. However, relatively small amount of pipe wall thinning, any profile related to fluid motion could not explain the profiles of pipe wall thinning.
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平井 淳也, 中村 隆夫, 天野 洋一
2013 年 79 巻 808 号 p.
2621-2625
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
Rules for PWR plant pipe wall thinning management were formulated by the Japan Society of Mechanical Engineers in 2006. Since then thinning management of Japanese PWR plants has been carried out based on this rule. Pipe wall thinning phenomena to be dealt with in this rule have been identified in many piping components of power plants. New technical knowledge has been accumulated since the issuance of 2006 edition. We have formulated these knowledge and information about the thinning phenomena in PWR power plants. Given the history of application of this rule, we have to make our best effort to carry out a study of latest technical knowledge and implement them to the revision of rule and improve pipe wall thinning management. This paper summarizes the new technical knowledge and basis to be implemented to the revision of rules on pipe wall thinning management for PWR plants in Japan.
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杉野 亘, 荒川 敬弘
2013 年 79 巻 808 号 p.
2626-2629
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
Flow Accelerated Corrosion (FAC) of carbon steel (CS) piping is one of main issues in secondary system of Pressurized Water Reactor (PWR) nuclear power plant. Therefore, Oxygenated Water Chemistry (OWC) as a new approach to FAC suppression for PWR secondary system was applied to condensate system of Tsuruga-2 (1160 MWe PWR, commercial operation started in 1987) in Jan. 2011. To evaluate the FAC mitigation effect of OWC, wall thickness of actual condensate piping in Tsuruga-2 after OWC application was measured by continuous monitoring system, using high-temperature and high-resolution ultrasonic probe. As a result, it was demonstrated that FAC was mitigated by more than 5ppb of oxygen under Low-AVT (pH9.3) condition, and FAC was almost stopped even in 2ppb of oxygen under High-AVT (pH9.8) condition.
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伊藤 啓, 高田 孝, 大野 修司, 粉川 広行, 上出 英樹, 今井 康友, 河村 拓己
2013 年 79 巻 808 号 p.
2630-2634
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
In a sodium-cooled fast reactor, inert gas exists in the primary coolant system as bubbles or dissolved gas. Such inert gas may cause disturbance in reactivity and/or degradation of IHX performance, and therefore, the inert gas behaviors have to be investigated to ensure the stable operation of a fast reactor. Similarly, small bubbles exist also in the mercury target loop in J-PARC to suppress cavitation erosion. Those small bubbles should be removed immediately at the downstream of a target region because the small bubbles may accumulate at the upper plenum of a heat exchanger and degrade the heat exchange efficiency. To simulate these inert gas behaviors in liquid metal flows, the Japan Atomic Energy Agency (JAEA) has developed a plant dynamics code VIBUL. In this study, new models, i.e. the bubble release and bubble carry under models, are introduced to simulate the bubble behaviors in the fast reactor and mercury target system. Then, the small bubble behavior in the mercury target system is simulated to check the validity of the new models.
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内堀 昭寛, 菊地 晋, 栗原 成計, 浜田 広次, 大島 宏之
2013 年 79 巻 808 号 p.
2635-2639
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
Multi-physics analysis system for a heat transfer tube failure event in a steam generator of sodium-cooled fast reactors has been developed. The analysis system consists of the multiple computer codes. In this study, applicability of the newly constructed numerical models in the analysis system was investigated. The droplet entrainment / transport model which was incorporated into the SERAPHIM code was verified through the analysis of the related experiment. The experimental data about the pressure variation when the droplet entrainment occurs was reproduced by our model successfully. The TACT code is integrated by the numerical models of fluid-structure thermal coupling, stress evaluation and failure judgment of the structure. The fluid-structure thermal coupling model could predict the temperature distribution formed by the flow around the circular cylinder. About the failure judgment model, the predicted time of failure occurrence showed good agreement with the results of the tube rupture simulation experiment.
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栗原 成計, 梅田 良太, 下山 一仁, 阿部 雄太, 菊地 晋, 大島 宏之
2013 年 79 巻 808 号 p.
2640-2644
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
Overheating tube rupture of adjacent tubes arises from water/steam leak in steam generators of sodium-cooled fast reactors. It is very important to predict the tube wall stress (tube wall temperature) with a high degree of accuracy on evaluation of overheating tube rupture, and is crucial to estimate quantitatively the heat transfer coefficient between reaction jet and adjacent tubes which is one of the major influencing factor. The authors carried out the sodium-water reaction test (SWAT-1R) under the simulated operation condition of a real plant, and measured the correlation between heat transfer coefficient and void fraction around an adjacent tube. The authors confirmed that thermal environment around an adjacent tube was inferable from measured data, and heat transfer correlation equation proposed by Hamada et al. was applicable to the operation condition at elevated pressure and temperature.
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早川 教, 渡辺 収, 伊藤 啓, 山本 智彦
2013 年 79 巻 808 号 p.
2645-2649
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
As the practical evaluation method of the effect of tsunami on buildings, the formula of tsunami force has been used. However, it cannot be applied to complex geometry of buildings. In this study, to analyze the effect of tsunami on the buildings of sodium-cooled fast reactor plant more accurately, three-dimensional tsunami analysis was performed. In the analysis, VOF (Volume of Fluid) method was used to capture free surface of tsunami. At the beginning, it was confirmed that the tsunami experiment results was reproduced by VOF method accurately. Next, the three-dimensional tsunami analysis was performed with VOF method to evaluate the flow field around the buildings of the plant from the beginning of the tsunami until the backwash of that.
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菊地 晋, 清野 裕, 大野 修司
2013 年 79 巻 808 号 p.
2650-2654
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
For countermeasure against sodium leak, structural concrete is protected by steel liner in a sodium-cooled fast reactor (SFR). However, if considering severe and unexpected accidental condition such as breach of steel liner by intensive sodium leak, the reaction with liquid sodium and concrete potentially may occur. For the purpose of elucidating the mechanism of the sodium-concrete reaction in SFRs, kinetic study of the sodium (Na)-silica (SiO
2) reaction has been carried out by Differential Scanning Calorimetry (DSC) technique. The Na-SiO
2 reaction temperature was identified from DSC curves. It was found that reactivity of Na-SiO
2 reaction is similar with the reaction between Na and aggregate of practical used concrete. Based on the measured reaction temperature, rate constant of Na-SiO
2 reaction was obtained. Thermal analysis results indicated that Na-SiO
2 reaction could occur under the elevated temperature in the timeframe of sodium-concrete reaction.
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鈴木 純也, 石田 卓久, 涌永 隆夫, 安田 光博, 横田 政和
2013 年 79 巻 808 号 p.
2655-2659
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
As the lessons learned by the Fukushima Daiichi NPP accident, Chubu Electric Power carried out emergency safety measures in Hamaoka NPP immediately and announced the plan of countermeasures for tsunamis in the NPP including the 18m-height protection wall in July 2011. Furthermore, the company announced the additional severe accident countermeasures in the NPP in December 2012, such as installation of the Filtered Containment Venting System and increasing the height of the protection wall from 18m to 22m. In this paper, we present major safety upgrading activities against tsunamis and earthquakes at the NPP.
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古市 紀之, チョン カーウィー, 寺尾 吉哉, 中尾 晨一, 藤田 啓司, 渋谷 和雄
2013 年 79 巻 808 号 p.
2679-2690
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
The discharge coefficient of a throat tap flow nozzle based on ASME PTC 6 are measured for Reynolds number range from 1.5×10
6 to 1.4×10
7 using the high Reynolds calibration rig in AIST,NMIJ. The discharge coefficients show apparently a dependency of a tap diameter and their behaviors are different from those of PTC 6. A deviation between the experimental results and the extrapolated discharge coefficient according to PTC 6 is 0.37% at
Red=1.4×10
7. To reduce the error in extrapolation, a new type throat tap flow nozzle which has different diameter taps is proposed in this paper. The derived equations of discharge coefficients of this throat tap flow nozzle are determined as a function of Reynolds number and tap diameter based on the experimental results from each different diameter tap. The error of extrapolated discharge coefficient using the derived equations is estimated to be less than 0.1% at
Red=1.4×10
7. The new type throat tap flow nozzle proposed is expected as high accurate flowmeter including the extrapolation for high Reynolds number.
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渡邉 智昭, 酒井 康彦, 長田 孝二, 寺島 修
2013 年 79 巻 808 号 p.
2691-2703
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
A reaction rate in a planar liquid jet with a second-order chemical reaction A+B→R is experimentally investigated. The jet flow contains the reactant A and the ambient flow contains the reactant B. The concentrations of reactive species are simultaneously measured by using the optical fiber probe based on the light absorption spectrometric method. The measurement result of mean reaction rate shows that the chemical reaction mainly occurs near the jet centerline in the upstream region, and the mean reaction rate is small in the downstream region. In the upstream region, lateral profiles of concentration correlation of reactants A and B have two local minimum values located away from the jet centerline, whereas the local minimum value of concentration correlation in the downstream region is located on the jet centerline. Comparison of concentration correlation of species A and B between the reactive and non-reactive cases shows that the chemical reaction makes the concentration correlation large near the edge of jet in the upstream region, whereas the opposite effect of chemical reaction on the concentration correlation can be seen in the other region. The concentration correlation of reactants A and B are estimated by using the Toor's hypothesis or the 3E model. The results show that the concentration correlation of reactants A and B estimated by using the Toor's hypothesis is smaller in magnitude than the experimental values, and the 3E model also fails to accurately estimate the concentration correlation.
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宮城 徳誠, 大西 真澄, 朝倉 洵, 佐用 謙太郎, 木村 元昭
2013 年 79 巻 808 号 p.
2704-2715
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
In this study, an attempt was made to control the diffusion of a round jet using a concentric dielectric barrier discharge plasma actuator. By changing the size of the electrodes, and the input frequency and voltage, it was confirmed that the jet diffusion characteristics could be controlled. By driving the plasma actuator, the induced flow was directed towards the central axis, and then ejected vertically from the wall. This lead to a velocity increase in the circular jet, which allowed control of velocity fluctuations and three-dimensional collapse of the jet structure. By changing the size of the electrode, it was possible to increase the volume flow rate of the main jet by the addition of the plasma induced flow. Decreasing the size of the exposed electrode caused enhanced contraction of the main flow. In contrast, larger electrodes caused the main jet to become wider.
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古市 紀之, チョン カーウィー, 寺尾 吉哉, 杉山 信幸, 小川 俊一郎, 吉村 紀之, 田邊 誠司
2013 年 79 巻 808 号 p.
2716-2727
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
Inter-laboratory comparisons for water flow calibration facilities between Advanced Industrial Science and Technology (AIST) and JCSS accredited companies are carried out for wide range flowrate from 0.005 m
3/h to 5000 m
3/h using many types of flowmeters. The purpose of this paper is to establish a reliability of the water flow calibration facilities in the JCSS accredited companies. The deviations of test results by each lab from AIST are almost less than ±0.1% and average one is ±0.025%. En values for all test results are less than 1 and geometric mean of En value is from 0.11 to 0.17. These results are equivalent level with the international key comparison operated by CCM/WGFF and indicate the high reliability of the calibration facilities in each lab. Moreover, the validity of the comparison method using multi-type flowmeters is also indicated.
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臼沢 太一, 木綿 隆弘, 樋本 航
2013 年 79 巻 808 号 p.
2728-2742
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
The present paper describes the flow characteristics of a plane air jet with deflectors. The divergent or convergent deflector was installed symmetrically inside of the plane nozzle. The effects of the angle and the length of deflectors on the mean and fluctuating velocities, and the velocity ratio of the inner jet to outer jet at the nozzle exit were examined by the hot-wire measurement and the flow visualization. In the case of the jets with the divergent deflector, the outer jet was accelerated and the inner jet was decelerated. The spreads of jet with the divergent deflector increased in the near field of the jet. In the case of the jets with convergent deflectors, the outer jet was decelerated and the inner jet was accelerated. The spreads of plane jet with the convergent deflector was smaller than the other jet. The relation between the velocity ratio of the nozzle exit, the area ratio, the pressure drop, the spreading rate and the virtual origin of a plane jet with divergent or convergent deflectors was found.
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鈴木 貴之, 加藤 千幸
2013 年 79 巻 808 号 p.
2743-2758
発行日: 2013年
公開日: 2013/12/25
ジャーナル
フリー
Over the past two decades, many types of homogeneous models have been proposed for the numerical simulation of cavitating flows. Homogeneous models represent cavitation by the media whose density continuously varies from the value corresponding to liquid to that to gas. Recent studies have, however, revealed that the present homogenous models are unable to predict the breakdown characteristics of cavitating hydrofoils. The objective of this study is to clarify causes of such inability of homogeneous models to predict breakdown characteristics of cavitating hydrofoil accurately. Theoretical analysis shows that the present cavitation models inevitably cause kinetic energy loss through expansion and contraction of the media. To illustrate this fact, we computed cavitating flows in a venturi and around a hydrofoil (NACA0015) with a homogeneous model and investigated the computed flow field in detail. It is shown that the expansion and contraction of the media based on the homogeneous model do in fact cause kinetic energy loss and as a result, a region of low velocity appears downstream of the cavity. This results in a decrease of lift force in a partial cavitation condition, which is not observed in the corresponding measurements.
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