All issues
Successor
Volume 57, Issue 535
Displaying 51-64 of 64 articles from this issue
-
Akira UMEMURA, Xin Yu ZHANG, Toshitaka FUJIWARA1991 Volume 57 Issue 535 Pages 1108-1113
Published: March 25, 1991
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSNumerical calculation was performed to examine the evaporation process of a single fuel droplet which is immersed in an otherwise quiescent, inert gas at high pressures. The conditions under which the droplet experiences the transition from the sub-to-supercritical evaporation regime were identified in terms of the initial parameters such as ambient gas pressure and temperature and droplet temperature. Consistent with the past experimental results no singular behavior is observed in the droplet temperature change at the instant of transition. The core which is characterized by high fuel concentration behaves like a liquid droplet and can be distinguished from the other parts by a sharp but continuous change at its boundary. Once the core is about to disappear, the concentration as well as the central temperature changes rapidly to assume the gaseous state.View full abstractDownload PDF (570K) -
Shinzo KIKKAWA, Mamoru SENDA, Katsuji SAKAGUCHI, Keisaku KASHIHARA1991 Volume 57 Issue 535 Pages 1114-1119
Published: March 25, 1991
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSA porous plate, which was cooled with water sprays, was horizontally placed parallel to a hot air stream. The air jets used to atomize the water were impinged on the back surface of the porous plate to increase the heat transfer coefficient and penetrated into the porous plate as a coolant, while the water also penetrated the porous plate and evaporated in it. The temporature distributions on both sides of the porous plate were measured by thermocouples. The temperature of the main stream and the mass fluxes of cooling air and water were varied in the range of 100∼300°C, (0.95∼5.70)×10-2kg/(m2·s) and (0∼1.6)×10-3kg/(m2·s), respectively, with the main strean being kept at a fixed velocity of 10m/s. The transpiration cooling effectiveness increases with increasing mass fluxes of water and air. The experimental results can be expressed by an empirical formula which is a function of a modified blowing parameter taking account of the latent heat of evaporation. The maximum and mean errors of the formula are 8.8% and 2.9%, respectively.View full abstractDownload PDF (577K) -
Min XU, Hiroyuki HIROYASU1991 Volume 57 Issue 535 Pages 1120-1127
Published: March 25, 1991
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSThis study investigated the effects of operating conditions and nozzle geometry, including injection pump speed, valve opening pressure, injected mass, nozzle hole diameter and length-to-diameter ratio L/D as well as nozzle sac volume, etc., on the spray tip penetration measured by a light sheet interception method. It is clarified that spray tip penetration mainly depends on initial injection pressure before the jet breaks up, and on the injection rate after its breakup, respectively. The nozzle geometry and ambient pressure also impact the spray tip penetration to a great extent.View full abstractDownload PDF (751K) -
Kotohiko SEKOGUCHI, Masao NAKAZATOMI, Hideo SHIMIZU, George MIYAKE1991 Volume 57 Issue 535 Pages 1128-1134
Published: March 25, 1991
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSThe effects of line pressure in gas-liquid two-phase plug flow cause a significant change in gas-liquid interfacial structures. The primary purpose of this study is to investigate the pressure effects on the liquid and gas slug in the plug flow regime. In this study, the pressure in the closed-loop system was changed from 0.3 to 20MPa at constant fluid temperature on vertical upward flow. The mean amplitude of the liquid slug, mean length of the gas and liquid slug, and mean liquid holdup around the gas slug were measured to investigate the characteristics of plug flow. In gas-liquid two-phase flow, the disappearance of the liquid slug brings about serious changes in the liquid transport mechanism. The approximate experimental equation for the points is presented.View full abstractDownload PDF (574K) -
Kazutumo OHTAKE, Ichiro NARUSE, Koichi HORIUCHI, Hirofumi TSUJI1991 Volume 57 Issue 535 Pages 1135-1140
Published: March 25, 1991
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSLocal and instantaneous structures as well as time-averaged characteristics of turburent diffusion flame were discussed by means of simultaneous multipoint measurements and visualization techniques. The turburent macroscale, the apparent flame velocity and the relation between signals of Rayleigh scattering and instantaneous flame structure were discussed. From these analyses, the following results were obtained. 1) The structure of the turburent diffusion flame was categorized into four regions. 2) The four regions defined by this study agreed well with those categorized by the time-scale division of temperature fluctuation. 3) The flame which periodically appeared due to the expansion caused by combustion generated a large roll-up eddy. 4) The flame structure in the mixing region of fuel and air was influenced by the Reynolds number. 5) The surrounding air was introduced into the fuel flow by the tangential eddy motion as well as by the axial and radial motions. 6) Simultaneous multipoint measurements were effective to decide the integral scale.View full abstractDownload PDF (562K) -
Hideaki KOBAYASHI, Michio KITANO, Eisaku MORI1991 Volume 57 Issue 535 Pages 1141-1146
Published: March 25, 1991
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSThe flow fields of a counterflow nozzle burner and counterflow twin flames for propane-air mixture stabilized with that burner were measured using LDV. The effects of the burner dimension, i.e., the outlet diameter of two opposed contraction nozzles and the distance between them, on the velocity profiles and extinction limits of the twin flames were examined. Results show that the effects of burner dimension on the extinction limit do not appear when the velocity gradient upstream of the front edge of preheating zone is used as a flow parameter and that the ratio of nozzle distance to nozzle outlet diameter is the main factor determining the dimensional effects on the flow characteristics. It is also shown that the flame stretch rate of the twin flames defined at the stagnation plane is about two times as large as that defined at the cold boundary of the flame.View full abstractDownload PDF (663K) -
Shuichi KAJITANI, Norihiro SAWA1991 Volume 57 Issue 535 Pages 1147-1153
Published: March 25, 1991
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSA characteristic of the injection rate of an emulsified fuel is investigated experimentally. As a result, the authors found out the following. The emulsified fuel contains a considerable amount of air-bubbles. When we define the air-bubble content as a function of water content y, namely z=ay, the value of is estimated about 0.5×10-4 to 1.0×10-4. Therefore, the sound velocity and the bulk modulus of elasticity decrease with increased water content. The increased viscosity of the emulsified fuel tends to advance the injection timing. On the other hand, the decreased bulk modulus of elasticity tends to retard the injection timing. Furthermore, the variation of air-bubble content in the emulsified fuel increases the variation of the injection timing, and of the injection rate during the injection.View full abstractDownload PDF (740K) -
Hideto IKEDA, Tetsuya HIRATA, Toshio MIYAUCII1991 Volume 57 Issue 535 Pages 1154-1160
Published: March 25, 1991
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSThe aim of this study is to simulate the combustion behavior in the combustor with plate catalysts. The burning of low-calorific gas composed of hydrogen and carbon dioxide was simulated, and the temperature of the plate catalyst and hybrogen burnout were predicted. From this study, the following conclusions were obtained. (1) If the excess air ratio, λ, is less than 2.4, the catalyst temperature distribution has a knick point, at which gradient of the temperature changes abruptly. (2) When λ is less than 2.4, the catalyst temperature and the burnout become large with the increase of λ, while when λ is larger than 2.4, the temperature decreases with the increase of λ and the burnout becomes constant. (3) When λ is constant, the burnout decreases with the increase of the velocity.View full abstractDownload PDF (556K) -
Norio KIMURA, Takayuki OGAWA, Hirofumi KUBOTA, Jiro SENDA, Hajime FUJI ...1991 Volume 57 Issue 535 Pages 1161-1166
Published: March 25, 1991
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSThere is a concept that the increase in the temperature of the charge in a combustion chamber and the shield of heat transfer through a chamber wall can facilitate soot oxidation and reduce soot discharge. In the experiments presented here, an IDI diesel engine installed with a bigger-size cylindrical swirl chamber with two quartz windows, which can be considered to be a piston cavity in a DI diesel engine, was used to inspect the concept. The experiments were carried out using two types of swirl chambers to examine the effects mentioned above. The first chamber was made of ceramics and the other was made of steel. In case of the ceramics chamber, the evaporation of fuel oil is promoted more, the vapor is spread more, the ignition delay is shorter, the area of the flame is larger, the area of high flame temperature is larger, a stabler combustion is maintained until the flame vanishes, the maximum pressure is higher and soot is distributed in a wider zone than in that of the steel chamber.View full abstractDownload PDF (631K) -
Yuji IKEDA, Shigeo HOSOKAWA, Tsuyoshi NAKAJIMA1991 Volume 57 Issue 535 Pages 1167-1174
Published: March 25, 1991
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSThree velocity components of the water flow in a model of a gas turbine combustor were measured using two types of developed FLDVs. In order to measure the third velocity component, that is, radial velocity, a small fiber LDV of 6 mm in outer diameter was developed and immersed into the water model. The flow structure of the primary zone was investigated by considering detailed velocity profiles. It was found that there are four characteristic flows in the combustor: the recirculating vortex, the reverse flow downstream of the bluff body, the reverse flow near the combustor wall, and the toroidal vortex at the center. The size of the recirculating vortex decreased and its position shifted upstream with increasing momentum ratio of the jet flow rate to the swirling flow rate. The flow velocities at the inlet boundaries were also measured for the study of the inlet condition of the numerical simulation in the upstream regions of the swirler exit and the primary jet ports.View full abstractDownload PDF (771K) -
Yuji IKEDA, Shigeo HOSOKAWA, Tsuyoshi NAKAJIMA1991 Volume 57 Issue 535 Pages 1175-1182
Published: March 25, 1991
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSThe flow structure and turbulence properties in a can-type model gas turbine combustor were investigated using two types of developed fiber LDV's. The behavior of the recirculation vortex formed in the primary zone was characterized with the negative flow rate and swirl number at different axial positions. It was found that the primary jets did not penetrate into the center axis but bent just from the exit and pushed the adjacent jet in the swirling direction, so that the toroidal vortex is formed near the center axis regardless of momentum ratio. The rms value of the three velocity components was measured and the turbulence energy profiles for different momentum ratios were obtained, which is indispensable to evaluate the numerical simulation. The outline of the flow in the combustor is drawn with four typical flows.View full abstractDownload PDF (811K) -
Tatsuro TSUKAMOTO, Susumu HASEGAWA, Jun'ichi SATO, Takashi NIIOKA1991 Volume 57 Issue 535 Pages 1183-1186
Published: March 25, 1991
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSLean blow-off limit and ignitable limit were studied experimentally to understand the effect of silane addition on the combustion performance of the gas turbine combustor. The fuel employed was methane. Silane concentration was varied up to 5%. The results show that silane addition to methane extends both the lean blow-off limit and ignitable limit considerably, and that this effect is more remarkable in the region of higher air velocity. It is concluded that silane addition makes the flame stable and promotes combustion reaction in the wide range of fuel-air ratio. However, silicon dioxide produced by silane burning adheres to the inner side of the combustor and accumulates around the fuel injection holes.View full abstractDownload PDF (521K) -
Itsuro SAKAI, Tadaaki MATSUHISA, Keiji KAWASAKI1991 Volume 57 Issue 535 Pages 1187-1193
Published: March 25, 1991
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSWe continuously tried to obtain a theoretical solution of equation from our published paper. An exact solution of original equation described the heat tranfer between a core and working fluids in a rotary regenerator with given boundary and initial conditions, is so complicate that the equation were convented to simultanious ordinary differential equation by using finite difference form in respect to the position. The approximate solution is shown in here and we have got transient temperatures of working fluids and the core from above solution and an effectiveness of rotary heat exchanger.View full abstractDownload PDF (558K) -
Hiroshi SEKIYA, Ryouichi KATOUNO1991 Volume 57 Issue 535 Pages 1194-1201
Published: March 25, 1991
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSIn the first paper, we presented the cycle simulation code of the Stirling engine, which was useful for researching and developing NS 30 S by virtue of predictions and evaluations. It was found that the calculated values of the engine performance and the P-V diagram were in good agreement with the experimental ones. In this paper, a comparative study of the engine performance in the case of using helium and hydrogen as the working gas is made from the viewpoint of thermophysical properties. By clarifying the characteristics of heat transfer and flow rate, the effects of heater tube temperature and cooling water temperature are investigated. In addition, the calculated results are inspected in comparison with the experimental ones concerning the test condition of temperature.View full abstractDownload PDF (848K)