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.
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.
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.