日本機械学会論文集 B編
Online ISSN : 1884-8346
Print ISSN : 0387-5016
76 巻, 767 号
選択された号の論文の14件中1~14を表示しています
  • 高園 康隼, 津田 和人, 許斐 敏明, 北原 辰巳, 中島 裕典
    原稿種別: 本文
    2010 年 76 巻 767 号 p. 1011-1018
    発行日: 2010/07/25
    公開日: 2017/06/09
    ジャーナル フリー
    In our previous study, we have developed a hybrid pattern gas flow channel design, where a serpentine flow channel is placed between interdigitated flow channels for polymer electrolyte fuel cells (PEFCs). In the present paper, using this flow channel design, we investigate the effects of gas flow direction on the output voltage under non-humidified cathode condition. As a result, we find a gas flow pattern that causes partial flooding by product water accumulation due to the gravity. Moreover, counter flow in the serpentine channel is found to increase the water content in the membrane, so that the fluctuation of the output voltages is suppressed. On the other hand, when the cathode outlet is downside, the above partial flooding is prevented. In addition to choosing this outlet, the counter flow of the serpentine and interdigitated flows is found to be effective to increase average output voltage and to suppress the fluctuation of the output voltage. In this case, the cathode outlet faces the inlet of the anode serpentine channel, where flow velocity is the highest in the anode flow channels. This gas flow pattern leads to sufficient supply of the product water at the cathode outlet to the anode side channels by the back-diffusion. Thus, the fluctuation of the output voltage is also minimized.
  • 宗像 瑞恵, 寺沢 亨, 吉川 浩行, 大庭 英樹
    原稿種別: 本文
    2010 年 76 巻 767 号 p. 1019-1027
    発行日: 2010/07/25
    公開日: 2017/06/09
    ジャーナル フリー
    The separation and secondary flow of surfactant solution with shear-thinning viscosity, in a square-sectioned 90° bend, has been investigated by measurements of velocity field using PIV and wall pressure distribution at the same bulk velocity, when Reynolds number is 45000 in the solvent (water). The surfactant solutions run with the transition state from the laminar to the turbulent. The shear-thinning viscosity is represented by power-law parameters, n and K. It is shown that the secondary flow and separation of manistream flow occurs at the upstream location in the bend as the pseudo-plastic viscosity K increases. For the downstream location, the intensity of secondary flow is so decreased that the mainstream runs through the larger radius of curvature. The existence of optimum shear-thinning viscosity, which induces the minimum intensity of secondary flow, is found. That means the detection of the critical profile in the transition state. The increase of pressure gradient in the radial direction at the upstream enhances the intensity of the secondary flow.
  • 斉藤 純夫, 永田 佳未, 高橋 正旭, 井上 大士郎, 星野 雄基
    原稿種別: 本文
    2010 年 76 巻 767 号 p. 1028-1034
    発行日: 2010/07/25
    公開日: 2017/06/09
    ジャーナル フリー
    This study focuses on water hammer pumps that can effectively use the water hammer phenomenon and allow fluid transients without drive sources, such as electric motors. An understanding of water hammer pumps' operating conditions and an evaluation of their basic hydrodynamic characteristics are significant for determining whether they can be widely used as an energy-saving device in the future. However, these conventional studies have not described the pump performance in terms of pump head and flow rate, common measures indicating the performance of pumps, and are not useful in fully evaluating the pump characteristics. As a first stage for the understanding of water hammer pump performance in comparison to the characteristics of typical turbo pumps, this study focuses on understanding the basic hydrodynamic characteristics of water hammer pumps and experimentally examines how the hydrodynamic characteristics are affected by the inner diameter of the drive and lifting pipes, the form and capacity of the air chamber, and the angle of the drive pipe, which are believed to be representative geometric form factors.
  • 染矢 聡, 内田 光則, 大倉 康裕, 李 艶栄, 岡本 孝司
    原稿種別: 本文
    2010 年 76 巻 767 号 p. 1035-1041
    発行日: 2010/07/25
    公開日: 2017/06/09
    ジャーナル フリー
    The surface temperature inside an optical engine both with and without heating the intake gas was measured. The temperature distribution was measured by a lifetime based phosphor thermometry using only three or 10 images recorded using a non-intensified high-speed CMOS camera by accounting for the pixel-to-pixel variation in the nonlinearity of the sensor. The luminescence from the phosphor was recorded at 40000 frames per second. A decay of luminescent intensity was represented by a mono-exponential function. The decay curves at various temperature conditions were fitted well to a quadric function, from which the decay constant at each temperature was obtained. The shot-to-shot standard deviation of the decay constant at uniform temperature conditions was 0.17〜0.33% and it varied ±0.15% with position, indicating that the pixel nonlinearity has a high nonuniformity. This technique was used to measure the temperature in an optical engine and it gave reasonable temperature maps.
  • 中島 誠治, 山田 彰二, 吉瀬 幸司
    原稿種別: 本文
    2010 年 76 巻 767 号 p. 1042-1047
    発行日: 2010/07/25
    公開日: 2017/06/09
    ジャーナル フリー
    The difference of the tip flow behavior in each operation points and the relation to the noise of the propeller fan with half-open-type casing were investigated through the measurement of the flow field of downstream by use of hot-wire probe and the pressure fluctuation on the casing wall with small pressure sensors. As a result, following conclusions were obtained. As flow ratio becomes smaller, the distance from the blade to tip vortex increases, and tip vortex interferes with casing more upstream. Velocity fluctuation at the downstream near the blade tip and pressure fluctuation on the casing wall have high correlation with the noise less than 200Hz, which indicates the tip vortex becomes the noise source less than 200Hz. The rate of contribution of the noise less than 200Hz to overall noise increases as flow ratio becomes smaller, and the control of the tip vortex is more important in small flow ratio to reduce the fan noise.
  • 久保 和範, 宮里 義昭, 松尾 一泰
    原稿種別: 本文
    2010 年 76 巻 767 号 p. 1048-1053
    発行日: 2010/07/25
    公開日: 2017/06/09
    ジャーナル フリー
    The effect of the boundary layer thickness on the choking phenomenon of a convergent nozzle flow has been experimentally investigated using four nozzles with the same diameter but different boundary layer thickness at the exit of the nozzle. When the flow is just choked, the cross-section where the main flow Mach number is unity is located upstream of the nozzle exit, and the main flow is accelerated to supersonic from the section to the nozzle exit. The fine structure of such a choked flow in a convergent nozzle is explained taking the boundary layer displacement thickness into consideration.
  • 金山 寛, 檀 啓
    原稿種別: 本文
    2010 年 76 巻 767 号 p. 1054-1060
    発行日: 2010/07/25
    公開日: 2017/06/09
    ジャーナル フリー
    In our previous papers, the two-layer viscous shallow-water equations were derived from the three-dimensional Navier-Stokes equations under the hydrostatic assumption. Also, it was noted that the combination of upper and lower equations in the two-layer model produces the classical one-layer equations if the density of each layer is the same. Then, the two-layer equations were approximated by a finite element method which followed our numerical scheme established for the one-layer model in 1978. Also, it was numerically demonstrated that the interfacial instability generated when the densities are the same can be eliminated by providing a sufficient density difference. In this paper, we newly show that conservation laws are still valid in the two-layer model. Also, we show results of a new physical experiment for the interfacial instability.
  • 阿部 順紀, 須藤 亮, 池田 満里子, 谷下 一夫
    原稿種別: 本文
    2010 年 76 巻 767 号 p. 1061-1067
    発行日: 2010/07/25
    公開日: 2017/06/09
    ジャーナル フリー
    The mechanical stimulus of shear stress enhances the function of endothelial cells as well as their microvessel network formation. Using an in vitro three-dimensional (3-D) model set in a parallel-plate flow chamber, we investigated the effect of shear dependency on 3-D microvessel formation. Bovine pulmonary microvascular endothelial cells (BPMECs) formed a monolayer on collagen gel and were exposed to the series of laminar shear stress (0.09-1.38Pa) for 48h in the presence of basic fibroblast growth factor. We found different number and spatial distribution of lamellipodia formed in the tip of the 3-D networks, which might promote the network extension. Furthermore, the morphology of the formed 3-D networks depended on the magnitude of shear stress whereas the network expansion in the horizontal plane did not. In particular, the network depth was significantly enhanced with the increasing magnitude of shear stress. These results demonstrate that the magnitude of shear stress is an important factor to control the formation of endothelial 3-D networks through lamellipodia formation.
  • 田川 正人, 貝吹 和秀, 保浦 知也, 山上 洋介, 加藤 健次
    原稿種別: 本文
    2010 年 76 巻 767 号 p. 1068-1074
    発行日: 2010/07/25
    公開日: 2017/06/09
    ジャーナル フリー
    A novel sensor technique is proposed to visualize the readily spatiotemporal behavior of a fluctuating temperature field of airflow. Two temperature probes were fabricated: one is a rod-type probe consisting of 24 two-thermocouple sensors set in line and the other is a plane-type one consisting of 64 two-thermocouple sensors arrayed on a two-dimensional grid (8×8 points). Each two-thermocouple sensor used in these probes was composed of two fine-wire thermocouples (type K) of unequal diameters, e.g., 25μm and 51μm. An adaptive response-compensation scheme was applied to accurately reconstruct rapidly-changing airflow temperatures. The plane-type probe enables visualization of fluctuating temperature fields of an artificially disturbed hot-air jet and adequate capture of the spatiotemporal behavior of a rapid circular motion of hot-air jet blown out from a hair dryer. A time-constant estimation scheme was proposed to estimate instantaneous time-constants which serve as a basis for a real-time response compensation technique for multidimensional temperature measurement. In addition, by scanning a temperature field with the rod-type probe, the temperature distribution can be reconstructed in one-dimensional space and time. This quasi two-dimensional visualization can become a prototype of a "scanner" for fluid temperature fields.
  • 宮本 年男, 大内田 聡, 長谷川 達也
    原稿種別: 本文
    2010 年 76 巻 767 号 p. 1075-1081
    発行日: 2010/07/25
    公開日: 2017/06/09
    ジャーナル フリー
    This paper shows numerical simulation to predict how a heat-pump system behaves in a variety of conditions and specifications. A model of heat-pump system, which consisted of a constant rotational speed compressor, a condenser, an evaporator, a decompression device and connecting tubes, was employed. Steady state governing equations for refrigerant flows and the state of refrigerant given by REFPROP 8.0 was solved by iterations. Characteristics of a heat-pump system with different heat transfer coefficients of condenser caused by degradation, different ambient temperatures and different specifications due to retrofit by installing an additional condenser and replacing refrigerant were predicted by the simulation. As a result, a decreased heat transfer coefficient (from 600W/m^2/K to 450W/m^2/K) reduced COP by 7%, and an increased ambient temperature (from 35℃ to 40℃) reduced COP by 10%. Installing an additional condenser to the degraded condenser reduced the work of compression by 5% and recovered COP to the rated value. Moreover replacing the refrigerant R22 with R134 a reduced the work of compression by 35% and increased COP by 15% while the cooling capacity became 75% of a rated value.
  • 佐藤 義久, 吉嶺 和哉, 森本 浩紀, 藤田 秀紀
    原稿種別: 本文
    2010 年 76 巻 767 号 p. 1082-1089
    発行日: 2010/07/25
    公開日: 2017/06/09
    ジャーナル フリー
    The purpose of this research is to clarify the requirements for the high output power SMA engine. The main results obtained by this research are as follows. In order to increase the output power of the SMA engine, it is necessary to make the radius of the high temperature wheel as small as possible, while the minimum value of this radius is restricted by the distortion of the SMA belt. On one hand, the output power of the SMA engine distinctly depends on the radius of the high temperature wheel and the diameter of the SMA belt. On the other hand, it slightly depends on the radius of the low temperature wheel and the length of the SMA belt. Thus, we experimentally verified that the output power of the SMA engine distinctly depends on the radius of the high temperature wheel and the diameter of the SMA belt.
  • 永井 二郎, 宮本 重信, 大澤 良和, 五十嵐 俊介, 柴田 和夫, 竹内 正紀
    原稿種別: 本文
    2010 年 76 巻 767 号 p. 1090-1101
    発行日: 2010/07/25
    公開日: 2017/06/09
    ジャーナル フリー
    Numerical simulation programs were developed for estimating temperature field and snow depth over a snow-melting system using geothermal energy assisted by heat storage during seasons. The system utilized a group of piles underground as heat exchanger and heat dissipation pipes near road surface, realizing solar heat storage from the surface into underground through seasons. Verification experiments for this system were conducted not only in relatively mild snowy region, Fukui, but also in frigid region, Sapporo. Numerical simulation results demonstrated existence of optimum space of a group of piles, where snow melting power becomes maximal. The obtained simulation results showed good agreements with the experimental data of both regions, demonstrating utility and validity of the programs. Also shown was that the proposed system can melt snow well in frigid region, Sapporo, without help of heat pump.
  • 篠森 健一, 加藤 孝輔, 彭 宏偉, 下栗 大右, 石塚 悟
    原稿種別: 本文
    2010 年 76 巻 767 号 p. 1102-1109
    発行日: 2010/07/25
    公開日: 2017/06/09
    ジャーナル フリー
    A self-recirculation type low NO_x burner, in which a fresh air is injected through a nozzle with a high velocity speed and a hot burned gas is involved into the air stream through a recirculation space, has been experimentally investigated. The flowfield has been determined with a PIV system and spatial distributions of NO_x, temperature, CO and O_2 have also been determined in a test furnace. Results show that a recirculation of a burned gas is indeed induced outside the air nozzle and the NO_x level is significantly reduced. In the present burner, the amount of a recirculating burned gas attains 50% the fresh air and the NO_x level is decreased below 20ppm. Further measurements indicate that a recirculating flow is also induced inside the air nozzle and combustion is stabilized around a stagnant region of this recirculation flow. With an increase in the air flow this inner recirculation zone expands and its centre approaches the fuel nozzle. The evaporation of liquid fuel is promoted, resulting in formation of blue flame. The NO_x level is further reduced to 18ppm for the air excess ratio of 1.6 in the present burner system.
  • 常吉 孝治, 高木 修, 山本 和弘
    原稿種別: 本文
    2010 年 76 巻 767 号 p. 1110-1117
    発行日: 2010/07/25
    公開日: 2017/06/09
    ジャーナル フリー
    In recent years, environmental regulation tends to become strict rapidly, and the further highly performance of DPF is demanded, which mainly consists of surface filtration and depth filtration. Generally, if the wall thickness is thin, the soot in diesel exhaust gas may break through and leak the filter, because the depth filtration doesn't work enough. However, most of filtration efficiency depends on surface filtration, because the soot cake forms on the surface of ceramic filter, and the soot cake takes part in highly performance of the filter. Therefore, the most important thing is how to make the soot cake rapidly. In this study, we pay attention to the surface roughness of ceramic filter. We observed the micro-porous structure of the filter based on SEM images. Also, we measured soot diameter and particle number concentration using different filters. Results show that, when too big open and too deep pore exist on the filter surface, the soot leakage occurs easily. In this case, it's hard to make soot layer rapidly and the soot leaks during initial DPF usage. Once the soot layer is formed, the filtration efficiency becomes high, and small particulates called SPM are caught effectively. Thus, it is important to control surface roughness for making soot layer rapidly.
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