JSME International Journal Series B Fluids and Thermal Engineering
Online ISSN : 1347-5371
Print ISSN : 1340-8054
ISSN-L : 1340-8054
Volume 45 , Issue 3
Special Issue on International Conference on Power and Energy System
Showing 1-40 articles out of 40 articles from the selected issue
PAPERS
  • Masao TOMIZAWA, Keisuke TAKESHITA, Keisuke TSURI, Yoshiharu AMANO, Mas ...
    2002 Volume 45 Issue 3 Pages 446-450
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The advanced co-generation system (ACGS) was built at Waseda University in 1999. The ACGS consists of a gas turbine, a steam turbine, an ammonia-water mixture turbine, an ammonia absorption refrigerator and an ice storage system. These turbine systems have a cascade relation upon the utilization of energy. Meanwhile, the ammonia-water mixture turbine and the ammonia absorption refrigerator located in the bottoming stage of the ACGS to utilize the lower temperature steam. In this paper, a mathematical model of the bottoming stage of the ACGS is established according to the experimental data. And, the operational planning of the bottoming stage with three cases of the cooling demand during the nighttime is also discussed.
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  • Takumi EBARA, Norihiko IKI, Sanyo TAKAHASHI, Jun HAMA
    2002 Volume 45 Issue 3 Pages 451-456
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    To reduce CO2 emission and environmental impact, it is needed to develop the clean and higher efficiency power generation system. So, the CO2 recovering semi closed gas turbine with CH4-O2 firing has been noted with its high efficiency and low emission capability. Such a high efficiency is a result of a high turbine inlet temperature. Though, high temperature causes the increase of emission level such as CO and H2 because of an incomplete reaction. Although, incomplete reaction can be suppressed in an oxidation surroundings actualized by excess oxygen feeding, it causes a decrease of system efficiency. So, chemical kinetic calculations are carried out to clarify the trade-off relationship between these parameters. The characteristics of pollutant formation and its oxidation processes are analyzed. An optimal equivalent ratio for the total system efficiency and emission is also estimated.
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  • Takayuki MATSUNUMA, Hiroyuki ABE, Yasukata TSUTSUI
    2002 Volume 45 Issue 3 Pages 457-464
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The unsteady flow field within an annular axial-flow turbine rotor at low Reynolds numbers was investigated experimentally using an LDV system. Detailed measurements of the time-averaged and time-dependent distributions of the velocity, the flow angle, and the turbulence intensity were carried out at the design operating condition. The obtained data was analyzed in terms of both absolute (stationary) frame of reference and relative (rotating) frame of reference. The effect of the turbine stator wake on the flow field inside the rotor passage was captured qualitatively and quantitatively. The unsteady flow was also analyzed using animations to visualize flow and thus clarify the unsteady phenomenon in a turbine rotor.
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  • Qiusheng LIU, Masahiro SHIOTSU, Akira SAKURAI
    2002 Volume 45 Issue 3 Pages 465-472
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Experimental apparatus and method for film boiling heat transfer measurement on a horizontal cylinder in forced flow of water and Freon-113 under pressurized and subcooled conditions were developed. The experiments of film boiling heat transfer from single horizontal cylinders with diameters ranging from 0.7 to 5mm in saturated and subcooled water and Freon-113 flowing upward perpendicular to the cylinders were carried out for the flow velocities ranging from 0 to 1m/s under system pressures ranging from 100 to 500kPa. Liquid subcoolings ranged from 0 to 50K, and the cylinder surface superheats were raised up to 800K for water and 400K for Freon-113. The film boiling heat transfer coefficients obtained were depended on surface superheats, flow velocities, liquid subcoolings, system pressures and cylinder diameters. The effects of these parameters were systematically investigated under wider ranges of experimental conditions. It was found that the heat transfer coefficients are higher for higher flow velocities, subcoolings, system pressures, and for smaller cylinder diameters. The observation results of film boiling phenomena were obtained by a high-speed video camera. A new correlation for subcooled flow film boiling heat transfer was derived by modifying authors' correlation for saturated flow film boiling heat transfer with authors' experimental data under wide subcooled conditions.
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  • Qiusheng LIU, Akira YABE, Shiro KAJIYAMA, Katsuya FUKUDA
    2002 Volume 45 Issue 3 Pages 473-480
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The study on thermal energy transport system by synthesis and decomposition reactions of methanol was reviewed. To promote energy conservation and global environment protection, a two-step liquid-phase methanol synthesis process, which starts with carbonylation of methanol to methyl formate, then followed by the hydrogenolysis of the formate, was studied to recover wasted or unused discharged heat from industrial sources for the thermal energy demands of residential and commercial areas by chemical reactions. The research and development of the system were focused on the following three points. (1) Development of low-temperature decomposition and synthetic catalysts, (2) Development of liquid phase reactor (heat exchanger accompanying chemical reaction), (3) Simulation of the energy transport efficiency of entire system which contains heat recovery and supply sections. As the result of the development of catalyst, promising catalysts which agree with the development purposes for the methyl formate decomposition reaction and the synthetic reaction are being developed though some studies remain for the methanol decomposition and synthetic reactions. In the fundamental development of liquid phase reactor, the solubilities of CO and H2 gases in methanol and methyl formate were measured by the method of total pressure decrease due to absorption under pressures up to 1500kPa and temperatures up to 140°C. The diffusivity of CO gas in methanol was determined by measuring the diameter and solution time of single CO bubbles in methanol. The chemical reaction rate of methanol synthesis by hydrogenolysis of methyl formate was measured using a plate-type of Raney copper catalyst in a reactor with rectangular channel and in an autoclave reactor. The reaction characteristics were investigated by carrying out the experiments at various temperatures, flow rates and at various catalyst development conditions. We focused on the effect of Raney copper catalyst thickness on the liquid-phase chemical reaction by varying the development time of the catalyst. Investigation results of the catalyst such as surface area, pore radius, lattice size, and photographs of scanning electron microscope (SEM) were also given. In the simulation of energy transport efficiency of this system, by simulating the energy transfer system using two-step liquid phase methanol decomposition and synthetic reactions, and comparing with the technology so far, it can be expected that an innovative energy transfer system is possible to realize.
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  • Hiromichi KOBAYASHI, Yoshihito ITO, Naoki TSURUTA, Kunio YOSHIKAWA
    2002 Volume 45 Issue 3 Pages 481-486
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Thermal performance in the experiments and three-dimensional numerical simulations for a high temperature air combustion boiler where fuel can be efficiently combusted by high temperature preheated air (800°C-1000°C) is examined. The boiler can burn not only natural gas but also low calorific gas (e. g. full gasification gas obtained from coal or wastes). In the boiler, four regenerative burners are installed. This boiler has new features that not only air but also gasification gas is heated up to 900°C, and combination of burners is switched every 15 seconds where two burners are used as inlets of fuel and air and the other two burners are used as outlets of exhaust gas. Natural gas and syngas obtained from coal are burned. The NOx emission for each fuel is less than 50ppm. The heat transfer of three-dimensional calculation is predicted higher than that of experiment.
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  • Wei WU, Kunio YOSHIKAWA
    2002 Volume 45 Issue 3 Pages 487-491
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    An innovative micro-gasification system for solid wastes is proposed in this paper, whose technical feasibility is demonstrated by using rubber chips as a fuel. In this system, a batch-type fixed-bed pyrolyzer combined with a high temperature steam/air reformer is employed. In the present investigation, it is shown that supply of high temperature air into the pyrolyzer significantly increases the heating value of the pyrolysis gas. With the use of high temperature steam/air mixture as an oxidant for reforming, almost complete reforming of the tar components can be done and they are decomposed into CO, H2 and other hydrocarbon gases with reasonable decrease of the heating value of the reformed gas compared with that of the pyrolysis gas. With packing ceramic balls in the reformer, reforming reactions can be accelerated. The experimental results demonstrate that almost soot and tar free clean reformed gas with the heating value of above 1000kcal/Nm3 can be generated from rubber chips.
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  • Akira SAKUMA, Toru TAKAHASHI, Toshihiro FUJIWARA, Masataka FUKUDA
    2002 Volume 45 Issue 3 Pages 492-498
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The improvement of efficiency has been one of the most significant aspects of the development and application of steam turbines, along with the improvement of reliability and gains in both reduced maintenance and extended operation. There is now extra emphasis on evolving increased efficiency, because of the environmental need to reduce the problem of carbon dioxide. On the other hand, a lot of the existing steam turbines which were designed and manufactured based on conventional production technologies of those days are now still operating, and the most units have been utilized for more than ten or twenty years, because recently the construction of new power generation plants has been restricted. And furthermore, in some aging existing steam turbines, the decreased performance, efficiency and availability have been discovered due to time deterioration of the turbine parts and components. Under these circumstances, upgrading and life extension for the performance and reliability of steam turbines is required particularly for the existing ones(1)-(3). This paper describes the recent development and application of advanced steam path design, such as nozzles and blades for improving performance and reliability, that is, the upgrading and life extension of existing steam turbines as well as new projects. And also it describes a repowering system for existing power plants using gas turbines. These components and technologies are applicable to both new and retrofitted units.
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  • Jiongming RUAN, Hideaki KOBAYASHI, Takashi NIIOKA, Abudula ABULITI, Fu ...
    2002 Volume 45 Issue 3 Pages 499-505
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The structures and stability of lifted combustion zones have been simulated with detailed chemistry and transport properties in an axisymmetric laminar fuel (CH4) jet and outer co-flow of the (O2+N2) oxidizer whose initial temperature is 300K, 700K and 1200K. A set of numerical simulations was executed by increasing the N2 dilution ratio, Z (mole fraction of N2 in the oxidizer). The results showed that at 300K, the lifted combustion zone had a triple flame structure where the rich premixed wing is smaller than the lean one and the trailing diffusion flame immediately inclined to the fuel side from the triple point as well as the leading edge of the triple flame was shifted away from the jet axis as Z increased. As the initial temperature increased, the combustion zones were lifted at larger Z values than the one at 300K. Especially, for 1200K, it was found that the lifted combustion zones, when expressed in terms of the heat release rate, have become so weak that a flameless triple combustion zone was formed due to the high dilution ratio and high preheat temperature. The numerical simulations on the response of the lifted triple combustion zone to the initial fuel velocity were also carried out, and the results showed that the lifted combustion zone using a high preheated temperature was very stable in the near field.
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  • Michitaka IKEDA, Yukitoshi KOZAI, Hisao MAKINO
    2002 Volume 45 Issue 3 Pages 506-511
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Sub-bituminous coal is considered to be one substitute fuel for bituminous coal. Since sub-bituminous coal contains more than 20% moisture, there are some problems with its utilization, such as a decrease in combustibility, high NOx emission and so on. This report describes the emission characteristics of NOx and unburned carbon in fly ash of sub-bituminous coal combustion through the use of a pulverized coal combustion test furnace. On the sub-bituminous coal combustion, ignition at the burner exit worsened and the combustion flame became diffused. Then, both NOx emission and the unburned carbon concentration in fly ash became high. In order to keep stable combustion and to form an effective NOx reduction flame, the swirl vane angle of secondary air was reduced and the Air/Coal ratio was lowered. As a result, the combustion flame became moderate, and both NOx emission and unburned carbon concentration in fly ash could be reduced.
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  • Ryo YOSHIIE, Shinya GOTO, Makoto NISHIMURA, Hiroshi MORITOMI
    2002 Volume 45 Issue 3 Pages 512-517
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The use of particulate kaolinite as a sorbent for capturing cadmium compounds in hot flue gas was studied in the influence of temperature and residence time on removal efficiency. More than a half of the cadmium fed into the reactor was captured by kaolinite samples. It was also found that the amount of cadmium captured increased with time and that the removal efficiency at a temperature of 1073K was slightly higher than at 873K. To clarify the mechanism of cadmium adsorption, the solubility of cadmium captured by particulate kaolinite was examined in both water and nitric acid. Acid-soluble cadmium constituted more than 80% of the total captured cadmium, while water-soluble cadmium constituted between 40-80%. This suggests that cadmium does not penetrate into the kaolinite particles, but it remains on the surface and that physical condensation accounts for approximately half of the cadmium aerosol captured by kaolinite particles.
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  • Saburo HARA, Jun INUMARU, Masami ASHIZAWA, Kazuyoshi ICHIKAWA
    2002 Volume 45 Issue 3 Pages 518-522
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    CRIEPI and Mitsubishi Heavy Industry, Ltd. have developed a pressurized two-stage entrained flow coal gasifier using a 2T/D bench scale gasifier. This type of gasifier was adopted for the 200T/D pilot plant project. The pilot plant test operation was started in March 1991 and was successfully finished in February 1996. Based on the results from the pilot plant, all Japanese electric power companies decided to construct the demonstration plant using the pressurized two-stage entrained flow type gasifier. In this type of coal gasifier, the product char is recycled to improve its efficiency. Using the experimental data of 2T/D gasifier, this report examines gasification characteristics such as product gas composition, cold gas efficiency and carbon conversion efficiency. Then, the effect of char recycle on gasifying efficiency and amount of product char is examined. Furthermore, per pass carbon conversion efficiency and fixed carbon conversion efficiency are evaluated.
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  • Kazuhiro KIDOGUCHI, Saburo HARA, Masami ASHIZAWA, Jun INUMARU
    2002 Volume 45 Issue 3 Pages 523-529
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    From the viewpoints of global environment and energy security, raising the thermal efficiency of a thermal power plant and the diversification of fuel are issues that must be resolved as soon as possible. As to resolving these two issues, it is very effective that extra heavy oil is used in a gas-steam combined cycle power generation system. Accordingly, in order to establish technology for supporting to rationally design and operate a gasifier using extra heavy oil, the Central Research Institute of Electric Power Industry (CRIEPI) targeted at clarifying significant phenomena in a gasifier, improving the accuracy of numerical analytical technique under development and verifying the technique. This report describes the major specifications of “Research Gasifier for Liquid Fuel” constructed in 1999 and the results of studies in respect to the reaction process in the gasifier based on OrimulsionTM (Trademark of BITOR) gasification tests in 2000.
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  • Toru TAKAHASHI, Eiichi KODA, Toshio MIMAKI
    2002 Volume 45 Issue 3 Pages 530-535
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    This paper shows the thermodynamic performance of gas turbine systems with air humidification. We make sure that humidifying the air increases the power output and thermal efficiency although air humidification method does not influence to the thermal efficiency greatly under the same calculating conditions. Moreover, humidifying the air is more effective in regenerative cycle, such as AHAT, TOPHAT, REVAP, and HAT cycle. They all show high thermal efficiency near 50%HHV. This is because the exhaust heat can be recovered enough by humidifying and the compressor power is decreased by each method in these systems. Moreover, the result of parameter studies show that the best efficiency of each system is comparable and each system has optimum point of moisture amount to the thermal efficiency.
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  • Jin'ichiro GOTOH, Yasushi HAYASAKA, Shigeo SAKURAI, Hiraku IKEDA
    2002 Volume 45 Issue 3 Pages 536-542
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The Life-Management System (LMS), for optimizing the reliability and maintenance costs of hot-gas-path components, was developed previously. Based on LMS, the Life-Management System with Remote Monitoring (LMSRM) for the real-time evaluation of damage and the residual life times of the hot-gas-path components of gas turbines was developed in the current work. Damage to these components is accurately evaluated by using a new equivalent operating time that takes data gathered by on-line sensors into account. The new equivalent operating time is thus calculated by using the number of start-ups/shut-downs, the number of variations in loading, and by such real-time data, as temperature, pressure, and composition of intake air.
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  • Keizo TSUKAGOSHI, Eiji AKITA, Yasushi FUKUIZUMI, Koji WATANABE
    2002 Volume 45 Issue 3 Pages 543-551
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The next generation 1500°C class “G-series” gas turbine has been developed by Mitsubishi Heavy Industries, Ltd.(MHI). MHI has been verifying its high performance and reliability of the latest technologies in the long-term field operation. This paper describes up-to-date operating status of both M501G (60Hz unit, in a combined cycle verification plant of MHI Takasago, Japan) and M701G (50Hz unit, in Higashi Niigata Thermal Power Station of Tohoku Electric Power Co., Inc., Japan).
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  • Eiichiro WATANABE, Hiroharu OHYAMA, Yasutomo KANEKO, Tosihiro MIYAWAKI ...
    2002 Volume 45 Issue 3 Pages 552-558
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    A low pressure end blade is one of the most important elements in designing the steam turbine, because it determines the performance, the dimension, and the number of casings of the turbine. Applying the state of the art technology to the aerodynamic and mechanical design, Mitsubishi Heavy Industries, Ltd. has been conducting a development program of new advanced low pressure end blades which adopt the ISB (Integral Shroud Blade) structure. A new standard series of these low pressure end blades has already been completed for 50Hz and 60Hz unit application including 3600rpm 45inch titanium blade, 3000rpm 48inch steel blade, and 1500/1800rpm 54inch steel blade which have the largest exhaust annulus area among the same class blades in the world. This paper reports on the up-to-date design technology applied to the new advanced low pressure end blades and on the verification tests to ensure the high efficiency and the reliability of the developed blades.
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  • Qiusheng LIU, Katsuya FUKUDA
    2002 Volume 45 Issue 3 Pages 559-564
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The knowledge of forced convection transient heat transfer at various periods of exponential increase of heat input to a heater is important as a database for understanding the transient heat transfer process in a high temperature gas cooled reactor (HTGR) due to an accident in excess reactivity. The transient heat transfer coefficients for forced convection flow of helium gas over a horizontal cylinder were measured using a forced convection test loop. The platinum heater with a diameter of 1.0mm was heated by electric current with an exponential increase of Q0exp(t/τ). It was clarified that the heat transfer coefficient approaches the quasi-steady-state one for the period τ over 1 s, and it becomes higher for the period of τ shorter than 1s. The transient heat transfer shows less dependent on the gas flowing velocity when the period becomes very shorter. Semi-empirical correlations for quasi-steady-state and transient heat transfer were developed based on the experimental data.
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  • Steffen RICHTER, Masanori ARITOMI
    2002 Volume 45 Issue 3 Pages 565-576
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    For studies on the characteristics of bubbly flow in a rectangular channel (20×100mm) a new electrode-mesh tomograph have been applied. The measuring principle is based on local conductivity measurement and a signal concerning. The applied sensor scans the local void fraction distribution in 2 parallel planes, separated 1.5mm in flow direction, with a resolution of 6.1×2.2mm and an overall sampling rate of 1200Hz (all 256 points). Algorithm for the calculation of the local instantaneous void fraction distribution and the true gas velocity are presented. Based on these values the approximate shapes of bubbles have been reconstructed and the gas volume flow through the sensor evaluated. The superficial gas velocity as well as the local distribution of the gas volume flux can be calculated. An extensive sensitivity study illustrating the applicability and accuracy is presented, based on experiment observations as well as theoretical considerations. The evaluated results are compared with high-speed video observations of the flow field as well as data comparing the reconstructed volume flow with measurements by a laminar flow meter. Good agreement can be stated.
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  • Hideki KAMIDE, Kazuyoshi NAGASAWA, Nobuyuki KIMURA, Hiroyuki MIYAKOSHI
    2002 Volume 45 Issue 3 Pages 577-585
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Decay heat removal using natural circulation is one of significant functions for a reactor. As the decay heat removal system, a direct reactor auxiliary cooling system has been selected in current designs of fast reactors. In this system, cold sodium is provided in an upper plenum of reactor vessel and it covers the reactor core outlet. The cold sodium can penetrate into the gap region between the subassemblies. This gap flow is referred as inter-wrapper flow (IWF). A numerical estimation method for such phenomena was developed, which modeled each subassembly as a rectangular duct with gap region and also the upper plenum. This numerical simulation method was verified by a sodium test and also a water test. We applied this method to the natural circulation in a 600 MWe class fast reactor. The temperature in the core strongly depended on IWF, flow redistribution in the core, and inter-subassembly heat transfer.
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  • Kazuo IKEDA, Masaya HOSHI
    2002 Volume 45 Issue 3 Pages 586-591
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Mitsubishi has developed a new zircalloy grid spacer for PWR fuel with higher thermal performance. Computational Fluid Dynamics (CFD) evaluation method has been applied for designing of the new lower pressure loss and higher Departure from Nucleate Boiling (DNB) benefit grid spacer. Reduction of pressure loss of grid structures has been examined by CFD. Also, CFD has been developed as a design tool to predict the coolant mixing ability of vane structures, which is to compare the relative peak spot temperatures around fuel rods at the same heat flux condition. Prototype grids were manufactured and several tests, which were pressure loss measurements, cross-flow measurements and freon DNB tests, were conducted to verify CFD predictions. It is concluded that the applicability of the CFD evaluation method for the thermal hydraulic design of the grid is confirmed.
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  • Nobuyuki KIMURA, Motohiko NISHIMURA, Hideki KAMIDE
    2002 Volume 45 Issue 3 Pages 592-599
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    A quantitative evaluation on the thermal striping, in which temperature fluctuation due to convective mixing imposes thermal fatigue on structures, is of importance for reactor safety. As for convective mixing, a water experiment was performed on vertical, parallel triple-jet: a cold jet at the center and hot jets in both sides. Three kinds of calculations based on the finite difference method for the experiment were carried out. Two types of turbulence models were used in the calculations, namely k-ε two-equation turbulence model (k-ε Model) and low Reynolds number turbulence stress and heat flux equation models (LRSFM). Furthermore, a quasi-direct numerical simulation (DNS) was performed. The DNS could simulate the time-averaged temperature field. The prominent frequency in temperature fluctuation obtained by the LRSFM was in good agreement with that in the experiment. The profile of power spectrum density of temperature fluctuations calculated by the DNS was close to the experimental results.
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  • Tadashi WATANABE, Kenichi EBIHARA
    2002 Volume 45 Issue 3 Pages 600-606
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Rising bubbles are simulated numerically as one of the fundamental two-phase flow phenomena using the two-component two-phase lattice Boltzmann method, since sharp interfaces are obtained and the coalescence and breakup of bubbles are simulated easily. The variation of interfacial area is measured for one or two rising bubbles. It is found that the interfacial area decreases during the coalescence of two bubbles while it increases during the breakup of a bubble. The change in the interfacial area is shown to correspond to the change in the shape of the bubbles.
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  • Hiroshi UJITA, Takashi IKEDA, Masanori NAITOH
    2002 Volume 45 Issue 3 Pages 607-614
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    SAMPSON is the integral code for severe accident analysis in detail with modular structure, developed in the IMPACT project. Each module can run independently and communication with multiple analysis modules supervised by the analysis control module makes an integral analysis possible. At the end of Phase 1 (1994-1997), demonstration simulations by combinations of up to 11 analysis modules had been performed and physical models in the code had been verified by separate-effect tests and validated by inegral tests. Multi-dimensional mechanistic models and theoretical-based conservation equations have been applied, during Phase 2 (1998-2000). New models for Accident Management evaluation have been also developed. Verificaton and validation have been performed by analysing separate-effect tests and inegral tests, while actual plant analyses are also being in progress.
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  • Toshihiko AWANO, Takeshi KANNO, Hiroyoshi UEDA, Takahiro KIMOTO
    2002 Volume 45 Issue 3 Pages 615-620
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Small and large scale tests were performed to evaluate technical feasibility of the monolithic buffer material, defined as a large block of bentonite formed by the cold isostatic pressing, for geological disposal of high-level radioactive waste. Trial manufacturing tests up to approximately 70%-scale of a Japanese disposal concept were carried out and emplacement tests were carried out by vacuum lifting and forklift-type methods for vertical and horizontal emplacement concepts, respectively. Based on the large engineering-scale tests, technical feasibility of the monolithic buffer was demonstrated.
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  • Morio FUJISAWA, Genichi KATAGIRI
    2002 Volume 45 Issue 3 Pages 621-625
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The spent ion exchange resin generated as radioactive waste in water purifying system at nuclear power stations or related facilities of nuclear power has been stored in the site, and its volume has been increasing year by year. We had developed a full-scale system of IC plasma volume-reduction system for the spent resin, and have performed basic performance test using some samples imitating the spent resin. As the results, the imitation of the resin can be reduced in volume by more than 90% so that the processing performance in actual scale was proved to be effective. In addition, it was clarified that the residuum after volume-reduction process is easy to mix with cement, and solidity containing 30wt% residuum provides high strength of 68MPa. Therefore, we evaluate the application of this process to stabilization of the disposal to be very effective.
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  • Kazuyuki KATO, Osamu AMANO, Hiroyoshi UEDA, Takao IKEDA, Hideji YOSHID ...
    2002 Volume 45 Issue 3 Pages 626-630
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    This paper presents a unified methodology to handle variability and ignorance by using probabilistic and possibilistic techniques respectively. The methodology has been applied to the safety assessment of geological disposal of high-level radioactive waste. Uncertainties associated with scenarios, models and parameters were defined in terms of fuzzy membership functions derived through a series of interviews to the experts, while variability was formulated by means of probability density functions (pdfs) based on available data sets. The exercise demonstrated the applicability of the new methodology and, in particular, its advantage in quantifying uncertainties based on expert opinion and in providing information on the dependence of assessment results on the level of conservatism. In addition, it was shown that sensitivity analysis can identify key parameters contributing to uncertainties associated with results of the overall assessment. The information mentioned above can be utilized to support decision-making and to guide the process of disposal system development and optimization of protection against potential exposure.
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Cavitation, from Cav 2001
  • Akihisa KONNO, Hiroharu KATO, Hajime YAMAGUCHI, Masatsugu MAEDA
    2002 Volume 45 Issue 3 Pages 631-637
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The appearance of cavitation bubbles near the bubble collapsing stage was investigated on the foil section with a high-speed video camera that was triggered by the signal of impulsive force sensor. The impulsive force always occurred with the collapse of cloud cavity, and in most cases the impulsive force peak was observed several frames (95µsec. in average) before the cloud cavity appeared to be minimum in its volume. To explain this phenomenon, the shock wave propagation in the bubble cluster into its center was discussed. The authors also simulated the behavior of bubbles numerically. Spherical bubble motion and mutual interference with other bubbles were considered. The results showed that the central bubble near the wall collapsed later than the surrounding bubbles and produced the highest pressure. At that moment the surrounding bubbles had been rebounding and were in growing stage. The results correspond qualitatively to the experimental results.
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  • Keiichi SATO, Yasuhiro SAITO
    2002 Volume 45 Issue 3 Pages 638-645
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The cavitation characteristics were experimentally investigated about long circular-cylindrical orifices of various throat lengths including the orifice with a trip wire. Especially, the shedding process of separated vortex cavity was examined using high-speed photography. Cavitation impacts were measured with an accelerometer. As a result, it is found that the periodic shedding of a cloud-like cavity can be observed in the transition cavitation stage and is dependent on the formation and coalescence of micro-vortex cavities on the separated shear layer, as well as the reentrant motion after the shedding. It is also pointed out that it forms a feedback loop in the self-exciting mechanism. A good estimation using two velocity ratios can be made on the Strouhal number of a cloud-like cavity. The clear shedding of a cloud-like cavity appears near the cavitation impact-peak region and remains almost constant irrespective of the difference in orifice length.
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  • Kotaro SATO, Masayuki TANADA, Sachie MONDEN, Yoshinobu TSUJIMOTO
    2002 Volume 45 Issue 3 Pages 646-654
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    An experimental investigation was made to clarify the characteristics of oscillating cavitation on a flat plate hydrofoil in a water tunnel. Dynamic behavior of oscillating cavitation is discussed from the unsteady pressure measurements at the upstream of the blade and the visual observations of cavitation phenomena using high-speed video recording. It was found that the mean cavity length characterizes the fundamental characteristics of cavity oscillation. The cavity oscillations are categorized into two types, i. e. the transitional cavity oscillation and the partial cavity oscillation.
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  • Yasutaka KAWANAMI, Hiroharu KATO, Hajime YAMAGUCHI, Masatsugu MAEDA, S ...
    2002 Volume 45 Issue 3 Pages 655-661
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Collapsing stage of cloud cavity and resulting violent shock pressure have been investigated by many researchers, because the knowledge of cavitation erosion is of practical importance and the dynamics is one of the most challenging problems in the field of two-phase flow. When a researcher intends to investigate the phenomenon numerically or experimentally, he or she must know the structure of the cloud cavity. The authors investigate cloud cavity, employing an off-axis laser holography system. This paper is a brief report concerning the inner structure of cloud cavity on a foil section.
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  • Seiji HIGASHI, Yoshiki YOSHIDA, Yoshinobu TSUJIMOTO
    2002 Volume 45 Issue 3 Pages 662-671
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Focusing on the tip leakage vortex cavitation, experimental and numerical studies were carried out as the first step of the investigation of cavitations in tip leakage flow. For a single hydrofoil with a tip clearance, tip leakage vortex cavitations were observed for various cavitation numbers and angles of attack. To simulate the tip leakage vortex cavitation, a simple calculation of 2-D unsteady flow based on the slender body approximation with taking into account the effects of cavity growth was made. The results of calculations show qualitative agreement with the experimental results with respect to the location and size of the cavity. The influences of the cavitation number, angle of attack, blade loading distribution, and the size of tip clearance were simulated reasonably well.
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  • Akinori FURUKAWA, Koichi ISHIZAKA, Satoshi WATANABE
    2002 Volume 45 Issue 3 Pages 672-677
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    An attachment of inducer is a powerful method to improve the cavitation performance of a turbo-pump. Cavitation surge phenomena, occurring under the severe suction pressure at a partial flow rate, is focused in the present paper. Flow measurements were carried out at the inlet and outlet sections of a flat-plate helical inducer with the solidity of 2.0 and tip blade angle of 11° by using a total-head yaw-meter with a phase locked sampling method in one period of the shaft rotation or the cavitation oscillation. Time variation of the flow distributions during the oscillation is clarified with observed cavitation behaviors. After these results are compared with those in conditions just before and after the oscillations, the fluctuating blade forces are estimated from the blade to blade distributions of casing wall pressures measured in these conditions.
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  • Olivier COUTIER-DELGOSHA, Jean-Luc REBOUD, Regiane FORTES-PATELLA
    2002 Volume 45 Issue 3 Pages 678-685
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    A numerical study of the cavitation behaviour of two-dimensional hydrofoils simulating a section of an inducer blade is presented. Two leading edge shapes were chosen to approach rocket engine inducer designs. They were tested with respect to the development of sheet cavitation. The numerical model of cavitating flows is based on the 3D code FINE/TURBOTM, developed by NUMECA International. The cavitation process is taken into account by using a single fluid model, which considers the liquid vapour mixture as a homogeneous fluid whose density varies with respect to the static pressure. Numerical results are compared with experimental ones, obtained in the CREMHyG large cavitation tunnel(1). Pressure distributions along the foil suction side and the tunnel walls were measured for different cavity lengths. Total pressure measurements along the foil suction side allow characterizing the effects of cavitation on the liquid flow. Influence of the leading edge shape on the cavitation behaviour and comparison between experiments and numerical predictions are discussed.
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Two Phase Flow
  • Toshihiko SHAKOUCHI, Dongbo TIAN, Toru IDA
    2002 Volume 45 Issue 3 Pages 686-693
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    An experimental study on the behavior of wake flow behind a square cylinder in an upward gas-liquid vertical two-phase flow especially about the effects of blockage ratio of flow passage was examined. The results showed that Karman vortex is shed regularly under certain flow conditions for various Reynolds number, void fractions and blockage ratios. Two uniform experimental equations were shown to describe the vortex shedding frequency f and pressure differenceΔP between the front and rear stagnation points of the obstacle for various blockage ratios. An entirely new method for measuring the flow rate of the gas-liquid two-phase flow by f andΔP was shown.
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Jet
  • Sok-Hyun JO, Moon-Uhn KIM
    2002 Volume 45 Issue 3 Pages 694-703
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The linear stability of two-dimensional jet issuing from a nozzle is considered from the view point of local similarity that is found while obtaining the basic flow by means of finite difference method. The results show that the local similarity can be used in the linear stability analysis when the Reynolds number is moderately large (ReL>100). In the case of low Reynolds numbers, since the nonparallel effects become apparent it is needed to carry out the stability analysis by using the basic flow's local similarity which can reproduce the velocity distribution at certain Reynolds number from a known one. And the neutral stability curves which are not coincide before reaching the similarity region with that of Bickley jet are presented by considering the local similarity variable ξ(=x/ReL) as a parameter. However there is a limitation in usage of this local similarity, which is also discussed.
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CFD
  • Paul Ndirangu KIONI
    2002 Volume 45 Issue 3 Pages 704-711
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    In this paper the detailed structure of velocity and pressure fields during and subsequent to instantaneous valve closure are presented. The full Navier-Stokes partial differential equations, formulated for a two-dimensional axi-symmetric flow geometry, have been solved to obtain the transient solutions. The Finite Volume Integration Technique together with a procedure involving splitting of operators is employed instead of the Method of Characteristics which is commonly used in the numerical solution of transient flows in pipelines. A solution in two dimensions, viz., in both the pipe axial and radial axis, is obtained for velocity and pressure. The well known oscillations of both the pressure and velocity components have been confirmed. However, it has been revealed, in this work, that the velocity field has a lot of structure in the radial axis which includes a region of re-circulation flow immediately upstream of the closed valve.
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Heat Transfer
  • Yao-Hua ZHAO, Takaharu TSURUTA, Takashi MASUOKA
    2002 Volume 45 Issue 3 Pages 712-718
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The critical heat flux (CHF) of subcooled boiling is theoretically predicted by means of the microlayer model. The enhancement of heat transfer for subcooled boiling is mainly due to the augmented heat convection caused by the forming and collapsing of individual bubbles. For a uniform heat flux surface, CHF approaches a constant in the high subcooling region. For a uniform temperature surface, CHF increases with the subcooling. The evaporative heat transfer becomes small and the total heat flux is mainly due to the heat conduction outside the evaporating area as the subcooling is increased. The boiling crisis (CHF) is caused by the local dryout of microlayer at low subcooling and by the rapid increase of the duration of bubble condensation with the increase of wall superheat at high subcooling.
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Combustion
  • Inyong CHOI, Kwang Min CHUN, Jae Won HAHN, Chul-Woung PARK
    2002 Volume 45 Issue 3 Pages 719-724
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The unburned end-gas temperatures in a combustion chamber of a conventional 4-cylinder DOHC spark-ignition engine were measured using the broadband CARS temperature measurement technique. The test engine was fueled with primary reference fuel 80 and gasoline with research octane numbers of 70.9, 83.4, 91.5 and 100.4. The measured CARS temperatures were compared with the adiabatic core temperatures calculated from the measured pressures. Significant heating by pre-flame reaction in the end gas zone was observed in the late part of compression stroke under both knocking and non-knocking conditions. The measured CARS temperatures when the cylinder pressures were above 1400kPa were higher than the calculated adiabatic core temperatures. These results indicate that some exothermic reactions exist in relatively low pressure and temperature regions. The CARS temperatures began to be higher than the adiabatic core temperature when the end-gas temperatures reached 700K. The temperature elevation due to the pre-flame reaction correlated well with the unburned gas CARS temperature for different research octane number fuels tested.
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  • Samir N. D. H. PATEL, Salah S. IBRAHIM
    2002 Volume 45 Issue 3 Pages 725-735
    Published: 2002
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The objective of the present paper is to develop and validate a newly formulated Flame Surface Density (FSD) model able to predict realistic turbulent burning velocities of premixed turbulent propagating flames over a wide range of flow conditions. Non-iterative transient numerical calculations of turbulent flame propagation in one-dimensional space are carried out over a range of turbulence Reynolds number using stoichiometric methane-air mixture. It is found that the new model closely predicts experimental data of turbulent burning velocity by Abdel-Gayed et al. (1987) as well as results from KPP (Kolmogorov, Petrovski, Piskonov) analytical method. The model formulation, and subsequent results of turbulent burning velocity and combustion regimes are presented and discussed in terms of the various physical processes that control flame/flow interactions in premixed combustion.
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