マリンエンジニアリング
Online ISSN : 1884-3778
Print ISSN : 1346-1427
ISSN-L : 1346-1427
37 巻 , 10 号
選択された号の論文の5件中1~5を表示しています
  • 武田 幸男
    2002 年 37 巻 10 号 p. 743-754
    発行日: 2002/10/01
    公開日: 2010/05/31
    ジャーナル フリー
  • 城戸 八郎, 橋本 武
    2002 年 37 巻 10 号 p. 755-762
    発行日: 2002/10/01
    公開日: 2010/05/31
    ジャーナル フリー
    The reliability index gives concrete evaluation value to improve the quality on the design side. On the other hand, the maintainability index gives a key for judgment of work load and to find crew's optimum number to the operator. However, the index for evaluating the ship operational efficiency is few so far.
    Availability index is one of the evaluating value for the ship operational efficiency. But if this index is applied to the marine plant, value of each equipment is very similar, because the each equipment MTTR is very short compare with the MTBF. The hazard index, which is proposed for the first time in this paper. Serious failure is a malfunction caused by the operation trouble like a stoppage and/or slow down of main engine. The cases of serious failure per 1000 hours is the serious failure rate. The hazard index is defined as the result of multiplying the effect hour per case [min/case] by the serious failure rate [cases/1000 hrs] . The effect hour means the operation delayed-hour due to trouble, which gives a serious effect on the operation performance. The hazard index is considered to be very appropriate for evaluating the ship operational efficiency. Because, the hazard index is a value of disable operation hour [minute] which is occurred during the operation for the 1000 hours, the size of this value is evaluation index of the ship's safety. This paper introdeces the reliability analysis on the serious failure situations which is the result of investigate on the statistical database.
    The data had been collected from 1982/3 to 1997/3 and this involved 186 diesel vessels and 27 turbine vessels. Total failure cases of Diesel Plant was 97131. And Steam Turbine Plant failure cases was 9269. As a result of evaluation value for the turbine plant by using the hazard index, the degree of operation hazard is 60 percent compared with diesel plant. The number of failures of equipment with alarm system is smaller than that of equipment without alarm by 10 to 20 percent. The operational efficiency can be expressed numerically by adopting the hazard index. And, present tendency shows the reliability index and safety index is strongly affected by man-hour, and it is clear that maintenance man-hour as well as the failure rate should be decreased.
  • 西田 修身, W. M. Faizal MAHMOOD, 麻野 純哉, 藤田 浩嗣, 原野 亘, 松井 孝一
    2002 年 37 巻 10 号 p. 763-769
    発行日: 2002/10/01
    公開日: 2010/05/31
    ジャーナル フリー
    工業用ボイラーには種々のノズルが用いられている.炭化水素燃料使用による環境への配慮は, 定格出力に対する燃焼量が少ないほど二酸化炭素の削減につながる.ノズルの使用にあたっては, 出力を1次圧力の変化無しに制御できる比例制御ノズル1本の場合や油圧制御ノズルを2, 3本装着し, 油圧により流量を制御する場合等がある.比例制御ノズルは主配管とバイパスとなる管を持ち, バイパスラインを通る流量をバルブにより線形に制御する事が出来る.油圧制御ノズルは1次圧力を調整する事によって, 流量を制御している.1本ノズルの比例制御及び2本ノズルの油圧 (段位) 制御の燃焼実験による排気ガス測定結果によると, 比例制御によって排出される窒素酸化物の値は, 油圧 (段位) 制御のものに比べて約20%低い値になっている.その原因は噴霧の重なりによるものなのか, 噴霧特性の差異によるものなのかは, 把握されていない.本研究には出力を等しいと仮定できる比例・油圧制御ノズル単体の噴霧粒子をPDPAを用い, 噴霧粒子の速度, 粒子径並びに数密度を測定し, 噴霧特性の観点から問題解明を目標とした.さらに, 実験に使用した比例制御ノズルの構造の違いによる差異の測定も行った.構造上の違いはバイパスラインへの戻り口 (穴) の径及び数の違いである.実験結果により, 比例制御ノズルの戻り穴の形状は噴霧特性に顕著な影響を及ぼしてはいない.油圧制御ノズルによる流量変化には粒子径変化が伴うが, 比例制御ノズルでの流量変化に対する粒子径の変化は確認できなかった.
  • 田辺 秀明, 木許 慎一郎, 加藤 聡
    2002 年 37 巻 10 号 p. 770-776
    発行日: 2002/10/01
    公開日: 2010/05/31
    ジャーナル フリー
    The effects of the spray impinging part on the in-cylinder air flow were numerically analyzed in the combustion chamber of the impinging diffusion direct injection diesel engine using KIVA 3 code. KIVA-3 code was enhanced to cater the impinging part as an internal obstacle by adopting the virtual droplet method, which is relatively easy to implement.
    Numerical result shows that the turbulence generation is promoted by the impinging part and is transformed by the squish flow into the piston cavity. The secondary flow is generated beneath the impinging part as well. The secondary flow area increases as the distance between top surface of the impinging part and bottom surface of the cylinder cover increases.
  • 劉 秋生, 福田 勝哉
    2002 年 37 巻 10 号 p. 777-785
    発行日: 2002/10/01
    公開日: 2010/05/31
    ジャーナル フリー
    The knowledge of forced convection transient heat transfer at various periods of exponentially increasing 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. In this study, the transient heat transfer coefficients for Helium, Argon, Air, and Nitrogen gases flowing perpendicular to a horizontal cylinder were measured in the low-Reynolds-number region. The platinum heater with a diameter of 1.0 mm was heated by electric current with an exponentially increase of Q0exp (t/τ) . It was clarified that the heat transfer coefficient approaches the quasi-steady-state one for the period τ over around 1 s, and it becomes higher for the period of τ shorter than about 1 s. Though the transient heat transfer region is influenced by both convection and the conductive heat transfer in the quasi-steady state heat transfer region, the conductive heat transfer becomes predominant as the period becomes short, especially in the region of within 200 ms. The transient heat transfer shows less dependent on the gas flowing velocity when the period becomes very short. Based on the experimental data, the ratio of transient heat transfer to the quasi-steady-state one was correlated as a function of Reynolds number of the gas flow and the non-dimensional period of increasing heat input. For the non-dimensional period larger than about 300, the transient heat transfer approaches the quasi-steady-state one, and shows no dependence on the Reynolds number.
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